Mechanical engineering
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ME4496FinalReport.pdf
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Attached is the report titled
Design of a System To Blend Deionized Water
With DuPont EKC265 To Increase Bath Life
Documenting work completed October 1, 2018 - April 21, 2019
This report provides background and details the design of a system by Team
ONEK to automatically add water to EKC at ON Semiconductor.
We hope you find this report satisfactory and please don't hesitate to contact us if
you have any questions.
Zac Shumway [email protected]
Steven Ferris [email protected]
Nouf Alhodaibi [email protected]
Shereen Aljumah [email protected]
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Design of a System To Blend Deionized Water
With DuPont EKC265 To Increase Bath Life
Team ONEK Zac Shumway
Steven Ferris
Nouf Alhodaibi
Shereen Aljumah Idaho State University
April 22, 2019
It has been shown that adding deionized water to EKC265 can extend bathlife
thereby saving time and cost. A precision monitoring and blending system has
been designed to perform that function automatically.
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A System To Blend Deionized Water
With DuPont EKC265 To Increase Bath Life
To:
Mr. Qutaiba Khalid, Process Engineer, ON Semiconductor
From:
Zac Shumway
Steven Ferris
Nouf Alhodaibi
Shereen Aljumah
Team ONEK
April 22, 2019
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Executive Summary
ON Semiconductor is a Fortune 500 semiconductors supplier company whose products include the manufacturing of microchips for electronic components. In the manufacturing process, circuits are created on wafers, and residues can accumulate on useful parts. EKC 265 residue remover is used to clean residue from the wafer after the etch manufacturing process. EKC is pumped through a tool closed loop system. EKC is sprayed on wafers then pumped back to a tank inside the tool. Water evaporates during this closed loop cycle, and the EKC becomes more viscous and less effective.
Research has found that restoring water content can increase the bath life of the EKC in the etching process. However, specific constraints on the EKC and its piping system require to design a new piping system with eventual heating components to make sure the mixing is indeed effective. Additionally, the fraction of deionized water in the mix of EKC solution should be between 12 and 18%.
The project at hand consists in designing a deionized water piping system to mix with the EKC to prolong the usability of the chemical for the residue removal etching process. Mr. Qutaiba, who’s an equipment engineer at ON Semiconductor, brought up the initiative, therefore is the mentor on the project. The project is conducted by four (4) mechanical engineering senior students, Shereen Aljumah, Nouf Alhodaibi, Zac Shumway, and Steven Ferris.
The fall semester of the project consisted in building the customer requirements and constraints for the system as well as coming up with different solution alternatives for solving the problem at hand. Distributing the different tasks on the project was also part of the results of the fall semester. The main tasks and therefore sections of this project are:
- Piping design and fluid dynamics of the deionized water piping loop system - Analysis of the refractometer and control system - Preheater analysis and selection and thermal aspects of system - Analysis of logic controller, transducers, and actuators and ladder logic construction
The piping design started by elaborating a whole layout with different pipe components to accomplish the task at hand. The layout consists of:
- A deionized water source - A pressure reducer to control the flow rate - A water preheater to preheat the deionized water before mixing it with the EKC - A flow meter to always check the flow rate in the system - A valve to control the gate of the new piping system to the existing system’s tank1
The first step was choosing the appropriate material for the system. After considering few criteria2 notedly the cost, the corrosion resistance, the ease of installation, and the flexibility, PTFE has been selected as the pipe material. A pneumatic DI valve was selected to control the flow of DI water to enter the tank in the existing system. Then a Malema M-2700 flow meter was chosen to check the
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flow rate and for proof of flow in the new system. With only a small amount of water needing to be added, a 1 GPM flow rate was chosen for the new piping system controlled with a PTFE pressure regulator. The sizing of the pipe yielded a 1/2“ PTFE tubing which then was then reduced to a 3/8“ PTFE tubing to increase velocity of the DI water to help mix the new water with the existing EKC mixture.3
The preheater analysis started with some design considerations and assumptions. The deionized water is assumed to be at room temperature (18-22°C). Thereafter, an intermediate temperature was chosen for the outlet of the preheater. That intermediate temperature was chosen to be 50 °C. Using the temperature rise, a preheater was sized from the vendor EEMAX. The preheater analysis yielded a 9.5- kW water heater from EEMAX with model number EX95T DI. Using this preheater, the time needed to heat the water the selected intermediate temperature was computed to be 0.95 seconds.4
System control is accomplished by an Allen-Bradley Micrologix 1400 PLC and analog input module housed in an enclosure on top of the EKC tool. The face of the enclosure will have an emergency stop, hand-off-auto switch, manual start button, and function indicator lights that serve as the human machine interface. The system will only function when given permission to run by the tool. A K-patents refractometer is used to evaluate the water concentration in the EKC, then the PLC uses that information to perform the necessary calculation and open a DI water valve for the required time. The closed loop is then given time to circulate and mix to achieve liquid homogeneity before evaluating the water concentration a second time. Ultra-pure deionized water compatible system components were specified as a part of this design in all instances.5
Final Budget: Part Quantity Unit price Total cost PTFE pressure regulator 1 $888.89 $953.20 PTFE Tubing 1/2“ 5 ft $17 $23 PTFE Tubing 3/8“ 5 ft $10.70 $16.69 PTFE Fittings 3 $34.47 $116.20 3/8“ Stainless Steel Tubing
2 ft $13.58 $29.44
Refractometer 1 $16100 $16100 MicroLogix 1400 PLC 1 $1920 $2035.20 Malema Flowmeter 1 $600 $600 DI Water Valve 1 $85 $90 Eemax DI water preheater
1 $1170.57 $1270.75
Total $21234.48 3 Steven Ferris 4 Nouf Alhodaibi 5 Zac Shumway
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Table of Contents67
Executive Summary Pages 3-4 List of Tables Page 6 List of Figures Page 7 Introduction Page 8 Additional Background Pages 8-9 Project Objectives Pages 9-10 Fluid Flow Discussion (Steven Ferris) Pages 11-15 Refractometer Discussion (Shereen Aljumah) Pages 16-29 Thermal Analysis and Discussion (Nouf Alhodaibi) Pages 30-37 Control Discussion (Zac Shumway) Pages 38-45 Management Page 46 Budget Pages 47-48
Conclusion Page 49 References Pages 50-51 Appendix Page 52 Gantt Charts and Responsibility Statements Pages 56-59 PLC Enclosure Drawings Pages 59-60 PLC Enclosure Specifications Page 61 Fuji 30mm Pilot Devices Specifications Pages 62-67 Selected Allen-Bradley Specifications Pages 68-78 RSLogix 500 Ladder Logic Pages 79-82 DI Water Valve Specifications Page 83 PTFE Standard Sizing Page 84 Malema M-2700 Flow Meter Specs Pages 85-87
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List of Tables8
Table 1-1, Design Alternatives Page 9 Table 1-2, Alternatives Decision Matrix Pages 9-10 Table S-1, Material Decision Matrix Page 11 Table S-2, Valve Decision Matrix Pages 11-12 Table S-3, Flow Meter Decision Matrix Pages 12-13 Table S-4, Flow Analysis Page 13 Table S-5, Flow Analysis and Fill Time Page 15 Table SH-1. The chemical curve parameters Page 24 Table SH-2: Calculated RI based on Temperature changes[2] Page 26
Table N-1, Water Heater Table Page 30
Table N-2, Preheater Decision Matrix Pages 31-32 Table N-3: Intermediate temperatures and corresponding computed times Page 35
Table N-3: Summary results from preheater sizing Page 37
Table Z-1, Logic Controller Decision Matrix Page 38
Table Z-2, PLC Input Assignments Page 41 Table Z-3, PLC Output Assignments Page 41 Table Z-4, Water Required as a Function of Concentration Used in Rung 3 Page 44
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List of Figures9
Figure B-1, SEM Image Page 9 Figure S-1: How Transit-time Ultrasonic Technology Works Page 12 Figure S-2: Solidworks Model of EKC Tank With 3/8“ Stainless- Steel DI Water Pipe by Steven Ferris Page 15 Figure SH-1: Solidworks for existing system Page 16 Figure SH-2: 3D Solidworks modification system Page 17 Figure .SH-3: Solidworks for modification system Page 18 Figure SH-4: Refractometer principle Page 19 Figure SH-5: Optical Images Page 20 Figure SH-6.1:Typical optical images without IDS Page 20 Figure SH-6.2: A slope graph without IDS Page 21 Figure SH-7.1: Typical optical images with IDS Page 21 Figure SH-7.2: A slope graph with IDS Page 22 Figure SH-8.1: Typical optical images with vertical borderline image detection Page 22 Figure SH-9.1: The six layers of concentration calibration Page 23 Figure SH-10.1: Data calibration BY www.k-patent.com[2] Page 25 Figure SH-11.1: Shows RI vs TEMP. Page 27 Figure SH-11.2: Show the relation at 65°C Page 27 Figure SH-13.1: Actual Sensor Photo By Qutaiba at ON Page 28 Figure SH-13.2: By Qutaiba at ON Page 28 Figure SH-13.2: By Qutaiba at ON Page 29 Figure N-1: General diagram of a water heater Page 31
Figure N-2: Power required chart from Eemax Page 33
Figure N-3: Model chart from Eemax Page 34 Figure N-4: Eemax EX95T DI Page 35 Figure Z-1. Enclosure Interior Housing PLC and Wiring Page 39 Figure Z-2. Enclosure Front with HMI Page 40 Figure Z-3, EKC tank drawing Page 42 Figure Z-4, Ladder Logic Rung One Page 43 Figure Z-5, Ladder Logic Rung Two Page 43 Figure Z-6, Ladder Logic Rung Three Page 44 Figure Z-7, Ladder Logic Rung Four Page 45
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Introduction
This report details a project to design and implement a system to monitor the mixture of water in a proprietary DuPont chemical PlasmaSolv EKC 265 (EKC) and add additional water to the mixture when required. As background information to readers unfamiliar with the semiconductor industry, semiconductor manufacturers such as ON Semiconductor use a variety of machines and processes to create circuit devices on silicon wafers. One particular process uses acids to etch circuitry directly on the wafer. Once the circuit is etched by acid, a residue remains on the wafer that must be cleaned off as shown in Figure B-1. EKC is used at ON Semiconductor for this purpose. EKC is dispensed from manufacturer supplied drums directly to a small tank inside a machine in which wafer cleaning takes place. Once inside the machine tank, EKC is then pumped to a nozzle that distributes the fluid on the wafer. EKC drains off of the wafer into a catch basin where it is then sent back to the machine tank where it can be pumped again onto the wafer for cleaning. As EKC continues through the flow loop and continues to remove residue, it becomes more viscous and more difficult to pump. Process engineers at ON Semiconductor and Dupont have found that deionized water can be mixed with EKC at low concentrations to reduce fluid viscosity and increase usable chemical life without adverse effects to the manufacturing process. Qutaiba Khalid at ON Semiconductor has requested that we design a system that will monitor the concentration of semiconductor grade deionized (DI) water mixed with EKC, then add DI water to EKC inside of the holding tank within the wafer cleaning machine. The concentration must be kept between their stated parameters of 12-18% water in a mixture with EKC. Doing so will increase the service life of EKC thus saving cost and reducing waste.10
Additional Background
“In an open bath under extract the typical bathlife of DuPont PlasmaSolv EKC265 post etch residue remover is 24 hours. This can be extended in a number of easily implemented ways. Within closed loop systems such as spray tools the recipe can be readily optimized to considerably extend bathlife.” [1] “The K-Patents Semicon Refractometers PR-33-S/-23-MS are designed for real-time concentration monitoring of wet chemicals used in the silicon wafer fabrication. The K-Patents refractometer provides a continuous measurement signal (4-20 mA or Ethernet output), which offers many possibilities for real-time monitoring and process controlling. Due to the unique digital measurement principle there is no signal drift. The main benefit of the real-time monitoring with the K-Patents refractometer is the potential yield improvement in the form of increased wafer throughput. This is achieved through extended bathlife and the optimization of chemical consumption. The exact chemical flow depends on bath chemistry and sequence, chemical concentration, cleaning time and temperature. The purpose is to process more wafers with an optimized chemical volume and to minimize equipment down times in the entire wafer handling process.”11 Additionally, “The K-Patents refractometer measures the concentration of the post etch 10 Zac Shumway 11 Steven Ferris
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cleaners, e.g. polymer removals such as EKC. This provides a real-time indication of the bath lifetime, which assists in increasing the wafer throughput and achieving significant savings in the chemical consumption.” [2]
Figure B-1, Scanning Electron Microscope (SEM) images of circuits before and after EKC cleaning.
Project Objectives The objective was to design a closed loop system that will continuously monitor the percentage of DI water in EKC, and add water to a holding tank inside the wafer cleaning tool to maintain a 12- 18% water concentration. Adding DI water to the system will extend the bath life of EKC from a current life of 125 cycles up to 400 cycles. There are a few constraints per Qutaiba Khalid. First, we must use a K-Patent brand refractometer to measure the water content in EKC. The K-Patent model has been used in this particular application and has been calibrated and adapted for this purpose. K-Patent manufacturer test data is available that correlates the analog signal to water content. Second, we must adapt our system to the EKC tool. We have at maximum 4 cubic feet of volume that we can use to incorporate all of our components. Third, all of our materials must be ultrapure compatible. Piping and instrumentation must not add any impurities to the EKC mixture or to the DI water itself. Finally, the system must maintain a liquid temperature of 60 degrees Celsius. Three design alternatives have been analyzed and are presented in Table 1-1 and Table 1-2.1213 Table 1-1 Design Alternatives Alternative 1 Alternative 2 Alternative 3 Valve DI water Preheater DI water Preheater Flow Meter Valve Pump Logic Controller Flow Meter Flow Meter Logic Controller Logic Controller
Table 1-2 Alternatives Decision Matrix Option Cost Installation Simplicity Control Total
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Alternative 1 5 5 3 2 16 Alternative 2 3 4 5 4 17 Alternative 3 2 4 4 5 13
Alternative 2 was selected as the best solution to design a closed loop water control system
based on cost, installation, simplicity, and control. Additionally, the design project was divided into separate specific components and assigned to
the four individual team members, Steven Ferris, Zac Shumway, Nouf Alhodaibi, and Shereen Aljumah. 14
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Fluid Flow Discussion
Steven Ferris is responsible for the fluid dynamics of the project, including sizing of pipes, selection of valves, as well as material selection and specifications. Three materials were considered for the piping and fittings for the design, PTFE, 316 stainless steel, and 304 stainless steel. Criteria for choosing the right material are cost, corrosion resistance, ease of installation and flexibility.
As seen in Table S-1. PTFE (Polytetrafluoroethylene) tubing was the most viable option due to its inertness or its ability to not put any ions back into the deionized water compared to both 316 and 304 stainless steel which react slightly with deionized water [9]. It was also the least expensive material at just over two dollars per foot [5] compared with stainless steel which is about 3-4 times more per foot. Stainless steel can be easily installed, PTFE tubing is very flexible allowing for less fittings and makes it overall the best choice for this design. Table S-1 Material Decision Matrix Option Cost Corrosion
Resistance Ease of Installation
Flexibility Total
PTFE 4 5 5 4 18 304 Stainless 3 3 3 1 10 316 Stainless 1 4 3 1 9
Valve Selection
When considering the valve that will control the flow of DI water in the system, a PTFE valve
was required in the ultrapure environment. The criteria for choosing a valve are cost, response, installation, and ease of use.
Three types of valve all with PTFE surfaces were considered: An electronic solenoid valve, a
Pneumatic Teflon valve, and a pneumatic DI valve. The valve would need to be opened when the PLC calls for water to be added the EKC system. All three options are manufactured by international polymer solutions and would work well for the design. As seen in Table S-2 the Pneumatic DI valve was chosen over the others because it had the lowest cost at $85 [3] and was manufactured for the specific use on deionized water in the semiconductor industry.
The DI valve will be pneumatically actuated with 40-80 psi using the PLC to control when to
open and close the valve. The valve is a 3/8“ FNPT (female pipe threads) connections and set in the normally closed configuration. 15 Table S-2 Valve Decision Matrix
Option Cost Response Installation Ease of Use Total Electronic Solenoid Valve
4 5 5 4 18
Pneumatic 2 4 5 4 17 15 Steven Ferris
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Teflon Valve Pneumatic DI Valve
5 4 5 4 18
Flow Meter Selection
Looking at the PTFE flow meter options there are two styles of ultrasonic flow meters, a flow through style and a clamp on style. Ultrasonic flow meters are an accurate way of measuring flow and is widely used in ultrahigh purity environments. Figure (S-1) shows how ultrasonic flow meters use transit-time ultrasonic technology to determine flow rate. Two piezoelectric transducers mounted at the ends of the measuring tube alternately transmit and receive ultrasound energy pulses. The difference between upstream and downstream transit time of the pulses is proportional to the velocity of the fluid, and is used to calculate flow rate.
Figure S-1 How Transit-time Ultrasonic Technology Works, Image From: [12]
The criteria used to determine the right flow meter are cost, maximum temperature, installation, and size. Of the three options that were considered the Metraflow and Malema M-2700 were flow through ultrasonic meters while the KATflow 150 was a clamp on flow meter. The flow meter is used to determine flow rate in the deionized water piping loop and proof flow in the loop. Proofing flow in the loop is used to make sure the system is running properly. If the valve were to become stuck open or not open at all the flow meter would show this as a continuous flow or as no flow allowing for an alarm to be set raised. The Malema M-2700 and the Metraflow were better choices due to the KAT 150 being a clamp on device which had a large unit that takes much more space than a flow through style meter. The system requires up to 65 degrees Celsius operating temperature, the Metraflow has temperature limit of 60 degrees Celsius [12] while the M-2700 had a much higher temperature limit of 180 degrees Celsius [4]. As you can see in Table S-3 the Malema M-2700 was the best choice for the design.16 Table S-3 Flow Meter Decision Matrix
Option Cost Maximum Temperature
Installation Size Total
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Metraflow 4 3 4 5 16 KAT 150 2 5 2 1 10 Malema M- 2700
4 4 5 5 18
Fluid Flow
The necessary amount of water that is to be added to the EKC bath is dependent on the current
water content of EKC after the spray cycle and the volume of the current EKC mixture. To determine the amount of water that could possibly be added to the system the volumes of both EKC and possible range of water content needed to be calculated.
The EKC system has approximately 10 ft of 1/2“ piping running from the tank to the system
tool. The amount of EKC mixture in the EKC tank and the 10 ft of piping with a fluid level at 12” diameter and 11” high would be approximately 5.44 gallons. Using a pressure regulator to control the small amount of water needing to be added, a 1 gpm flow rate will be used. Table S-4 below shows if the water content is at the minimum value of 12% the amount of water needed to get to the maximum value of 18% would be approximately 0.4 gallons. This is the maximum amount of water that would need to be added to the EKC system. Letting the system reach the minimum value of 12% or a maximum value of 18% would cause the EKC to perform improperly resulting in semiconductor wafers to be wasted costing the company thousands of dollars. To prevent this from happening it is more effective for the DI water additive system to add water when the percentage of water content in EKC drops below 14% and fill to 16%. In this range the amount of water needed is approximately 0.13 gallons.17 Table S-4 Flow Analysis
Total Volume (in3/gal)
% Water
Water Volume (in3/gal)
EKC Volume (in3/gal)
Volume of Water Added to get to 18% water content (in3/gal)
Volume of Water Added to get to 16% water content (in3/gal)
1258/5.44 12 151/0.65 1107/4.79 92/0.40 60/0.26
1258/5.44 14 176/0.76 1082/4.68 61/0.26 30/0.13
1258/5.44 16 201/0.87 1057/4.57 30/0.13 0/0
1258/5.44 18 226/0.98 1032/4.47 0/0 n/a
A desired flow rate of 1 gpm was chosen to allow for good control of how fast the DI water will be added. 1/2 inch PTFE piping will be run from the outlet of the DI water system into a pressure regulator to reduce the 30 psi that the DI water system has initially. The 1/2 inch pipe will then run into and out of the DI water preheater to heat the water from room temperature to up to 65℃. The 1/2 inch pipe will then be reduced to 3/8 inch PTFE piping to increase the velocity of the water from 2.9 ft/s to 17 Steven Ferris
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6.9 ft/s. The increase in velocity will help mix the DI water being add with the EKC mixture. The 3/8“ tubing will run through the flow meter and DI water valve. The 1/2 inch and 3/8 inch piping has inner diameters of 3/8 inch and 1/4 inch respectively. Using these inner diameter values, the corresponding areas of the pipe are calculated to be:
Where D is the internal diameters of the pipe.
Rearranging the flow rate equation below the velocities in the 1/2 inch and 3/8 inch pipe are calculated respectively:
Modified Bernoulli’s Equation below is used to determine the pressure required for the system.
Rearranging Bernoulli’s Equation assuming the height of inlet and outlet are the same, the outlet is open ended, and Ignoring losses from friction due to the smooth surface of PTFE piping resulting in a small coefficient of friction and the total length of piping being under 10 ft, the required pressure is calculated to be:18
The values calculated above have been placed in table S-5 below.
Table S-5 Flow Analysis and Fill Time PTFE Tubing Size (in)
Inner Diameter (in)
Desired Flow Rate (Gpm)/(ft3/s)
Velocity (ft/s)
Required Pressure (psi)
1/2 3/8 1/0.002228 2.9 0.226 PTFE Tubing Size Inner Diameter Desired Flow Rate Velocity (ft/s) Required Pressure
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(in)
(in)
(Gpm)/(ft3/s)
(psi)
3/8 1/4 1/0.002228 6.53 0.226 Valve Open for 1 Sec (gal)
Valve Open for 5 Sec (gal)
Time Required to Fill 0.13 gal (sec)
Time Required to Fill 0.26 gal (sec)
Time Required to Fill 0.40 gal (sec)
0.016 0.083 7.8 15.6 24 The outlet of the system is designed to help mix the DI water with the EKC while it's being added. This will help with getting an accurate reading from the refractometer of the change in water percentage quicker. Figure (S-2) below shows how the piping will be mounted along the side wall of the EKC tank. The piping along the inside of the tank will be made with 3/8 inch stainless steel and curved at a downward angle. The stainless steel will be tack welded to the tank holding it permanently in place.19
Figure S-2 Solidworks Model of EKC Tank With 3/8“ Stainless Steel DI Water Pipe by Steven Ferris
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Refractometer Discussion
Shereen Aljumah is responsible for P&ID design layout, as well as specification of the refractometer PR-23. Sample refractive index and calibration information. DI water in system.
● Layout Design
The cleaning process of the wafers by the EKC system has been done at ON Semiconductor in the past using a single piping loop system. The purpose of the project is to significantly increase the usability of the EKC solutions for the cleaning process. The principle this project is based on is that EKC becomes reusable when added to a specific amount of deionized water. Therefore, the project will design a secondary piping loop system for the deionized water to be preheated to facilitate and optimize the heating time of the mixed solution. The design layout of the overall system will be described in the following lines.
Figure SH-1 Solidworks for existing system
1. Existing system
The existing system at ON Semiconductor is a 25-ft piping loop consisting of a process chamber, a bypass valve, a flow meter, a white knight pump, a sensor, and the EKC tank.
● Process Chamber
This is the chamber where the EKC is processed to be able to effectively etch the surface of the cassettes and wafers.
● Bypass valve20
The bypass valve main purpose is to bypass the system when needed. Due to the extremely precise temperature that the EKC solution needs to be at, the piping loop has some temperature sensors that read the temperature of the EKC solution at any given instant, and whenever the temperature is not
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exactly 65 °C, which is the necessary temperature of the EKC solution for the etching process. The bypass valve sends the solution back to the tank when the temperature of the EKC solution is not right.
● Flow meter
The flow meter measures the flow rate of the solution in the piping loop
● White Knight Pump
The white knight pump will pump the EKC solution
● EKC Tank
The EKC tank is where the EKC is initially heated to the appropriate temperature for the etching process. With the design of the new system, it will also be where the deionized water will be mixed with the EKC then heated to the appropriate temperature. It is 12 inches in diameter and 13 inches deep.
1. Deionized water piping system21
The system has a 7-ft secondary piping system to supply the deionized water to be added to the EKC tank. This piping is composed of the DI water source, a pressure regulator, a water preheater, a flow meter, and a valve.
Figure SH-2 3D Solidworks modification system
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Figure SH-3 Solidworks for modification system
Everything in black is the existing system. I’m going to explain every element in the ne system which we are modifying the system. 22
● Refractometer
The temperature sensor in the system detects the temperature of the EKC solution and sends feedback to the controller to assure the solution is at the right temperature for the etching process. A refractometer is specified to analyze the concentration of DI water in EKC in the tank. The refractometer transmitter will give us a reading of the concentration as a function of refractive index.
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● DI water source
The deionized water will be obtained from the DI water distribution system. DI water coming in is room temperature, and pressure can be regulated and flow rate can be adjusted as required.
● Water preheater
The water preheater is tasked to preheat the deionized water to an intermediate temperature before mixing it with EKC solution to render it more reusable. Preheater will preheat the DI water up to 50°C.
● Programmable logic controller
Based on the outputs of the sensor the PLC will open or shut the valve.PLC receives water concentration and determines if water needs to be added. PLC calculates how long the DI water valve needs to open to get to set point and preforms action.
● Pressure regulator
½ inch tubing will exit pressure regulator and connect to the DI water preheater.
● Flow meter
Flow meter helps us to control the valve to maintain the concentration. The control signal is send by the PLC which works off the refractive index measurement.
Measurement Principle The K-Patents inline refractometer sensing device estimates the refractive index nD the solution
being processed. It is used to find the critical angle of refraction by shining a yellow LED light source with the same wavelength of 580 nm as the sodium D line. Light coming from the LED source shown in fig.1 below is guided to the interface between the prism (P) and the sodium process (S). Both surfaces of the prism perform the job of mirrors and light rays are refracted so that they meet the interface at different angles.23
Figure SH-4 Refractometer principle
The refracted light rays produce an image (ACB), where C is the position of the critical angle ray. The rays at A are totally internally reflected at the process interface, and the rays at position B are 23 Shereen Aljumah
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refracted partially and also reflected to some extent into the process solution. The division of optical image is done by this method into a light area A and a dark area B. The refractive index can then be determined by this position. The change in refractive index nD depends upon the process solution concentration and the temperature. Refractive index behaves as directly proportional to the concentration. But at higher temperature the value of refractive index is low. The optical images changes with the process solution are shown below in the fig.4
Figure SH-5 Optical Images
Viewing sensor status Optical Image
There are two different image detection algorithms in the PR-23. The original used algorithm has been complemented with an advance IDS (image detection stabilization) algorithm which gives the alternative for some unwanted noise in the image. These systems differ only in the appearance but meaning of all the diagnostic values is same.
By the use of original detection algorithm the optical image graph should look like fig.5.1 below in right side. The vertical dotted line shows the position of shadow edge. For empty pipe the optical image looks like Figure SH- 5.1 left side. The soft key slope refers to a graph like in Figure SH- 5.2. This is what refractometer software curves look like24
Figure SH- 6.1 Typical optical images without IDS
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Figure SH-6.2 A slope graph without IDS
Optical image with IDS For the IDS enabled image detection algorithm the images look like Figure SH-6.1 and the
slope like Figure SH-6.2. 25
Figure SH-7.1 Typical optical images with IDS
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Figure SH-7.2 A slope graph with IDS
It should be noted that the empty optical image may have left and right edge close to edge of the image. In the example the only right edge is visible.
Optical image with VD A PR-23-GP can be arranged in an order with option -VD, vertical borderline image detection.
Particularly this is used in a sugar vacuum pan. By this method the optical image is without IDS and slides of the image are straight and slightly sloping. This is done by programming, the optical module in the sensor is the same as for a PR-23-GP without the -VD option.26
Figure SH-8.1 Typical optical images with vertical borderline image detection
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Refractive data outputs Six layers organization of the concentration calibration of the K-Patents inline refractometer
PR-23. Using CCD for measuring light intensity or refractive index.
1. The information from CCD element and Pt-
1000 temperature element. The projection
Of the shadow edge (Figure 7.1, “Optical
Image detection”) is identified by a respective number called CCD and is scaled down
from 0-100%.
Figure SH-9.1 The six layers of concentration calibration
2. The sensor calibration: The CCD value is used to find the real or experimental refractive index nD. The Pt-1000 resistance will give the value of process temperature. The symbol for the sensor output will be nD and for temperature sensor reading will be TEMP and the units will being degree Centigrade. As the calibration of all PR-23 sensors are similar so the sensors can be used interchangeably. Standard refractive index liquids as given in Chapter 13 can be used to verify the calibration of individual sensors.
3. The chemical curve: The Indicating transmitter DTR receives the sensor output nD and TEMP from the temperature sensor and finds the concentration value based on the chemical curves deduced from the contemporary chemical literature and K-Patents expertise. And from this the value of temperature compensated concentration value will be found.
4. Field calibration: As the value calculated above of concentration value mostly based on theoretical base so in order to incorporate the real condition adjustment may be required to fit the measurement to the experiment results of laboratory. The field calibration procedure, described in section 6.4.3, will be used for the adjustment to the calculated results. After the adjustment of calculated value previously CALC will be called as CONC. CALC and CONC are equal when no adjustment is incorporated. The adjustment is only an additional term and the chemical curve is kept intact and use as a reference for calculations.27
5. Damping: The damping is applied to the CONC value of the current sensor. The PR-23 has three types of signal damping.
a) “Damping parameter: Is set separately through the outputs menu selected from calibration menu by 2 output.
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b) Exponential damping: works for most processes and is the standard choice for slow and continuous processes.
c) Linear damping: If the process has fast step changes, linear (fast) damping gives shorter settling time. In the linear damping (fast damping), the output is the running average of the signal during the damping time. “[12].
6. Output signal: Two endpoints on the CONC scale defines the range of the 4 to 20 mA.
The chemical curve TEMP and nD are the base for the chemical curve which is theoretical concentration curve. 16 parameters define the chemical curve. (Table1, one set for each sensor).
C00 C01 C02 C03
C10 C11 C12 C13
C20 C21 C22 C23
C30 C31 C32 C33
TableSH-1. The chemical curve parameters
Scaling range of refractometer transmitter ● Example specific to our project
The sensor output from the transmitter will be 4-20mA where 4mA indicates 0 water concentration and 20mA indicates 205 water concentration. So, to configure the sensor at 0-20% water concentration, it means we want the PLC to recognize 0% as the minimum(zero) and 20% as the maximum. The difference between max and min is the span, which is 20-0=20.28
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Refractometer PR-23GP The most important part of refractometer analysis is to find the relation between the refractive
index and concentration of water in EKC. This graph shows the calibration data from K-patent base on refractive index.
Figure SH-10.1 Data calibration BY www.k-patent.com[2]
This between the refractive index and temperature refractive index = 1.47 mA and temperature = 24.8 °C. They also come up with an equation 29
n^20=n^′+0.004(T-20) :[2] Where :
n^20: is the refractive index at 20
n^′: is the refractive index at any temperature T: is the temperature
The K-patent was knowing the relation and the temperature at which refractive index was experimentally determined. Here is the table shows the values of refractive index for EKC265.
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Table SH-2 Calculated RI based on Temperature changes[2]
There is little difference between published reference RI =1.4474 mA and measured RI =1.4485 mA30 Calibration curve
Figure SH-11.1: Shows RI vs TEMP.
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Figure SH-11.2 Show the relation at 65°C
Here is what I did to determine the refractive index at 65°C. I have used Excel program to determine the RI which is I’m looking for to get the relation between RI and temperature. I have determined the refractive index at 65°C i got value = 0.57 that means if we have high temperature will have a small refractive index.Temperature and refractive index values are usually determined at standard temperature. A higher temperature means the liquid becomes less dense and less viscous, causing light to travel faster in the medium. This results in a smaller value for the refractive index. The slope at the graph was linear at higher temperature and then its start curving down by decrease the temperature.
As far as experimentation, or in this case more of a qualification of refractometer calibration, at some point in the future samples will be taken from the EKC tank and labeled with the corresponding refractometer reading. Those samples will be sent to the EKC manufacturer and/or an independent testing laboratory to be analyzed. That analysis will confirm or refute the accuracy of the existing factory calibration. In my experience, refractometer based transducers are inherently extremely accurate and do not tend to drift from zero or change in scaling over time, hence little need to re- calibrate often. The K-patents refractometer comes pre-calibrated from the factory for this exact application.31
Some Info from ON
The refractometer was installed on the tool on Tue April 9, 2019
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Figure SH-13-1: Actual Sensor Photo By Qutaiba at ON32
PR-23-GP parts list
Figure SH-13.2: By Qutaiba at ON
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Figure SH-13.3: By Qutaiba at ON33
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Thermal Analysis and Discussion
Nouf Alhodaibi is responsible for the thermodynamic aspect of the design. She is quantifying heat losses and sources of the current EKC system and evaluating the need for temperature transducers and liquid heaters. She has determined that a DI water in-line preheater with a single heating element is appropriate for the design. Her decision is presented as Table N-1 Table N-1 DI Water Preheater Decision Matrix Option Cost Efficacy Installation Size Total One Element 4 3 4 5 16 Two Elements 3 4 3 3 13 Three Elements 1 5 2 2 10
Preheater analysis and thermal aspects of the system
The system consists of two piping loops (as shown in figure XX). Through the first loop flows the EKC chemical and through the other one flows the deionized water. The deionized water is at room temperature (18-20 °C). It is imperative to keep the EKC at 65 °C for the etching process, hence critical to keep the two fluids in different compartments until the mix is at exactly 65 °C. The deionized water is supposed to mix with the EKC only in the tank and the mix heated to the appropriate temperature before the mix is pumped and used for the etching process.
To reduce the time taken to heat the mix EKC-DI water to the appropriate temperature, a preheater is needed in the deionized water piping loop. The preheater will consist in heating the deionized water to an intermediate temperature between room temperature (18°C) and the EKC operating temperature (65°C). Thereafter, the tank heater will heat the mix of EKC and DI water to the EKC operating temperature. The intermediate temperature will be determined by a MATLAB simulation to minimize the time to heat the mix in the tank. The following figure shows the general components of a water heater from Marey heaters.34
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1. Selection of appropriate preheater35
The fall semester resulted in selecting an appropriate preheater for this application. The selected preheater was the Eemax tankless preheater with three heating elements. After analysis, it appeared that the initial selection of preheater was too costly and not powerful enough to reduce significantly the time to heat the mix EKC-DI water.
Therefore, another analysis was necessary to find a different preheater capable to accomplish the task more efficiently. After analysis, a one-heating-element tankless preheater was selected for the application. Sizing the water preheater was the next step on the thermal analysis; however, this cannot be done without choosing an appropriate intermediate temperature that the water preheater will heat the DI water to.
2. Choice of an intermediate temperature
Choosing an appropriate intermediate temperature is important to minimize the overall time needed to heat the mix EKC-DI water. To choose this temperature, an iterative process was used. The first step of the process consisted in partitioning the range of temperature values from 20°C to 60°C with increments of 5°C. This range was chosen because the initial temperature is 18°C (room temperature) and the final temperature is 65°C (EKC operating temperature). Then, for each temperature, both the time to heat the DI water to that temperature and the time to heat the mix DI water – EKC in the tank were computed, and the total time for the heating operation was computed by summing the two previous times. The choice of optimum intermediate temperature for the preheater was made based on two criteria: the total heating operation time and the cost of preheater associated with this intermediate temperature. The following table shows the selected temperatures with the results of operating times for both the preheater and the existing tank heater. The table also contains the overall cost of a preheater corresponding to each heating operation. The costs were taken from Eemax vendor’s website. The detailed MATLAB code and results are displayed in Appendix XX.
Table N-2: Intermediate temperatures and corresponding computed times:
Preheater Time (sec)
Tank Heater Time (sec)
Total Time (sec) Cost of preheater (from Eemax)
20 0.13 188.04 188.17 $387.41
25 0.45 167.15 167.60 $399.99
30 0.66 146.25 146.92 $457.55
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Fig. N-1: General diagram of a water heater
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35 0.73 125.36 126.09 $678.85
40 0.85 104.47 105.32 $897.64
45 0.87 83.57 84.44 $989.99
50 0.95 62.68 63.63 $1,170.57
55 0.95 41.79 42.74 $1,580.49
60 1.02 20.89 21.91 $1,690.25
The calculations and this summary results table show that the intermediate time for the preheater that minimizes the overall heating time is 60°C. However, the cost of acquiring a preheater that heats from room temperature to 60°C is relatively high meanwhile an intermediate temperature of 50°C is about 1 minute and costs few hundreds of dollars less. Therefore, the intermediate temperature of 50°C was selected for the preheater outlet.
3. Assumptions and design considerations
To complete the task of sizing the preheater, some assumptions must be made, and design considerations taken into account. The first major assumption to consider is the flow rate in the DI water piping system. This assumption mainly comes from the piping design. The piping design yielded a small flow rate of 4 liters per minute (1.05 gpm). An assumption of 1 gpm was then made as the flow rate in the secondary system. The outlet temperature of the preheater was selected in the previous section to be 50 ℃. In addition, room temperature was assumed to be 18℃. This temperature corresponds to the inlet temperature of the water preheater. Also, the water preheater will be acquired from Eemax, a water heater vendor.
4. Preheater sizing36
To size the preheater, the first topic to consider is power. To choose the needed power for the preheater, two things must be considered, the flow rate in the pipe and the temperature rise. The assumed flow rate in the pipe is 1 gpm. For this application, the temperature rise is given as follows:
T_rise=Outlet Temp-Inlet temp
The outlet temperature is the selected intermediate temperature in subsection 2 of the preheater analysis section. The outlet temperature is 50 ℃. The inlet temperature corresponds to the room temperature and was chosen to be 18 ℃. The calculation for the application yields a temperature rise of 32 ℃ (about 60℉). Using these two types of information, the power required for the application can be
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determined. To do so, a power required flow chart from the vendor website was utilized. The chart and the selection of the power needed are given as follows:
37The flow chart shows that the correct power to accomplish the application is 9 𝐾𝑊. Using this
power obtained and a model chart from the vendor site, an appropriate model of preheater is chosen. The model chart from the site and the selection are displayed as follows:
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Fig. N-2: Power chart from EEMAX
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The chart says to use a 13 kW model; however, since the needed power is only about 9 kW, another preheater was selected from the subcomponents of the model. The model chart shows that the appropriate model for this application is the EX95T DI. The power delivered by this model is exactly 9.5 KW. It is rated to a voltage of 240 V for 54 A. The connection type is a ½” pipe with adapter included.38
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Fig.N- 3: Model chart from EEMAX
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39Table N-3: Summary results from preheater sizing
Manufacture EEMAX
Model EX95T DI
Power delivered 9.5 KW
Height 10 ¾”
Width 5 ¼”
Depth 2 7/8”
Inside pipe diameter ½”
Length of inside pipe 24”
Max flow rate 4.8 gpm at 60 psi
Efficiency 99.8 %
This is a picture of the preheater to acquire for the heating operation of the application.
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Fig. N-4: EEMAX EX95T DI
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This water heater is literally not only more powerful, but also less expensive than the one selected at the end of the fall semester. This change will significantly reduce the time needed to heat the DI water before mixing it in the EKC tank. It will also reduce the overall time of heating operation in the EKC tank.
5. Calculation of time needed to heat DI water
This is the more technical section of the analysis. The section will prove that the preheater analysis optimizes in fact the time of the heating operation. The calculation of time goes through necessary considerations of power, fluid properties, and temperature rise. The general equation for heat transfer is as follows:
𝜂 ∗ �̇� ∗ 𝛥𝑡 = 𝜌/0123 ∗ 𝑉 ∗ 𝐶𝑝/0123 ∗ (𝑇9 − 𝑇;)
Where:
● 𝜂 is the efficiency of the water heater ● �̇� is the power delivered by the water heater ● 𝛥𝑡 is the time required to perform the heating operation ● 𝜌/0123 is the density of water ● 𝑉 is the volume of water in the pipe inside the device at any time ● 𝐶𝑝/0123 is the specific heat of water ● 𝑇9 is the final temperature at the outlet of the device ● 𝑇; is the initial temperature at the inlet of the device
The temperature rise is as stated in previous sections to be 50 ℃ − 18℃ = 32℃.
Fluid properties are read for water at an average temperature of CD℃EFG℃ H
= 34 ℃. Properties are read from engineering toolbox. The density of water is read to be 𝜌/0123 = 1000 𝑔/𝐿 and the specific heat of the water is read to be 𝐶𝑝/0123 = 4.19 ∗ 10N𝐽/𝐾𝑔𝐾.
The volume of water inside the device at any instant is given by the total volume of pipe inside the device. The volume is given by:
𝑉 = 𝜋 4 ∗ 𝐷;R
H ∗ 𝐿
Where:
● 𝐷;R is the inside diameter of the pipe ● 𝐿 is the total length of the pipe
The inside diameter of the pipe is read for the ½” specification pipe from engineering toolbox (see Appendix 4) to be 0.546 𝑖𝑛. The length of the pipe inside the device is given from the specifications of the device on the vendor’s website. The length of the pipe is 𝐿 = 24 𝑖𝑛.
The volume of water inside the pipe is then computed to be 𝑉 = 0.092 𝑙.
The power delivered by the water heater is, as stated in the previous sections, 9.5 𝐾𝑊. The efficiency of the device is 99.8%. Both specifications were obtained from the vendor’s website.
The time required to heat the DI water from room temperature (18 ℃) to the selected intermediate temperature of 50 ℃ is then computed to be 0.95 𝑠𝑒𝑐𝑜𝑛𝑑𝑠.
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6. Evaluation of preheater40
Having a preheater in the system loop was questionable at first because the EKC tank already had a heater, the DI water could have been sent directly to the tank, mixed with the EKC, and the mix heated to the appropriate temperature (). In this case scenario, the heating operation time would have been computed using the following formula:
𝑄 ̇ ∗ 𝛥𝑡 = 𝑠_𝐸𝐾𝐶 ∗ 𝜌_𝑤𝑎𝑡𝑒𝑟 ∗ 𝑉_𝑡𝑎𝑛𝑘 ∗ 𝐶𝑝_𝐸𝐾𝐶 ∗ (𝑇_𝑓 − 𝑇_𝑖)
The parameters for this formula are:
· Q ̇ is the power delivered by the tank heater, 3 kW
· Δt is the time required to perform the heating operation
· s_EKC is the specific gravity of the EKC, 1.104
· ρ_water is the density of water, 1000 kg/m^3
· V is the volume of mix in the tank, 5 gal
· Cp_EKC is the specific heat of water, 5*10^3 J/kgK
· T_f is the final temperature, 65℃
· T_i is the initial temperature, average weighted temperature of the DI water and the EKC. Since the DI water is just 15% of the volume of the mix, this initial temperature is computed as
0.15*18℃+0.85*65℃=57.95℃.
The heating time is then computed to be 196.40 seconds.
By using the preheater, the overall time to heat the mix EKC – DI water is reduced to 63.63 seconds, so about 67%. Therefore, using a preheater in the DI water loop is efficient and proven to work.41
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CONTROL DISCUSSION
Zac Shumway has specified a Programmable Logic Controller (PLC), assigned inputs and outputs for transducers and actuators, and written ladder logic to perform the automatic EKC rehydrate function. Three logic controllers were compared for suitability for this design, those being the ELC manufactured by Eaton, the Micrologix 1400 manufactured by Allen-Bradley, and the ControlLogix 5570 Manufactured by Allen-Bradley.
Cost is factor when choosing a PLC but only if each different model under consideration has the
same level of reliability. If any information indicates that a PLC has a lower cost due to the fact that it may fail unexpectedly, that PLC will not be included in a group of candidates in the first place. The second PLC selection criteria was Supervisory Control and Data Acquisition (SCADA) flexibility. There are many communication protocols in use to electronically send and receive information to and from a logic controller to a remote location. The transmitted information might include alarms, system status, or recipe uploads. A PLC should support a wide variety of the most common SCADA protocols in order to integrate with older existing methods as well as support newer more advanced methods. The third selection criteria was PLC processing power. The PLC processor must receive signals, interpret programming, then change the status of outputs. This must be done quickly for proper system control. The final selection criteria was physical PLC size. Smaller physical size increases location options. More location possibilities can sometimes lead to a reduced cost of wiring to and from the PLC. These four selection criteria are quantified below in a decision matrix, Table Z-1.
Table Z-1 Logic Controller Decision Matrix42 Option Cost SCADA
Flexibility Processing power
Size Total
Eaton ELC 5 2 3 4 14 Allen Bradley MicroLogix 1400
4 4 4 5 17
Allen Bradley ControlLogix 5570
2 5 5 3 15
The Allen bradley MicroLogix 1400 PLC was chosen due to price point, broad support of SCADA protocols, fast processing power, and small size. The Allen-Bradley MicroLogix 1400 Programmable Controllers Users Manual was referenced for design. [13] Allen-Bradley MicroLogix 1400 part number 1766-L32BXBA is 24vdc powered, with 24vdc sinking/sourcing digital inputs. A 1762 analog expansion module is used to provide 4-20ma analog input from the refractometer. The PLC will be housed in a 316 Stainless Steel Hubbell-Wiegmann Ultimate series enclosure, model number N412161606SSAC, that fastens on top of the EKC tool. The PLC and expansion module will be snapped to a 35mm x 15mm DIN rail. Wiring terminal blocks may be snapped to the DIN rail to
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keep wiring organized as desired by the installer. A length of Iboco T1E-1015G-1 series open slot thin finger wire duct will be mounted above and below the PLC to keep wire routing in order. Wiring from tool inputs and to system outputs must be routed from inside the tool to the enclosure. See Appendix pages 52-54 for additional enclosure dimensions and specifications. See Appendix pages 61-71 for selected MicroLogix 1400 specifications used for design purposes. ON Semiconductor Line Maintenance Personnel must implement their own wiring diagram.
Figure Z-1. Enclosure Interior Housing PLC and Wiring43
Human Machine Interface (HMI)
The system has a Human-Machine Interface (HMI) in the door of the enclosure so an operator
can place the system in Automatic Mode, Manual Mode, or Off to provide operator permission to run. The HMI consists of an Emergency Stop Button (E-Stop), Hand-Off-Auto (HOA) switch, an instant push button, and 3 indicator lights. These switches and lights will be the Fuji 30mm series found in the appendix, pages 54-59. At any time whether the system is running or not, the E-Stop can be pressed and all functions will stop. Nothing will continue unless the E-stop is disengaged by pulling it outward. When switched to Automatic mode, the system will complete all tasks to automatically add water to the tank whenever the tool is idled. In Manual Mode, an operator will have to press the instant start push button for the process to begin. Additionally the system can be turned off. These switches reside in a small enclosure on top of the tool. Three indicator lights are mounted in the top enclosure as well. One labeled System Running, one labeled Adding Water, and one labeled Ready To Run.
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44 Figure Z-2. Enclosure Front With HMI
Inputs/Outputs (I/O) System information inputs additional to the HMI inputs are 1) a tool status input, 2) a pump
status input, 3) a flowmeter or flow switch input, and 4) the refractometer analog input. Inputs and outputs are assigned to specific locations numbered 0-N, on the PLC, and are shown
below in Figures Z-2 and Z-3.
Table Z-2. PLC Input Assignments
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Table Z-3. PLC Output Assignments45
EKC Tank Considerations
The EKC tank in the tool has dimensions of 12” diameter by 13” height, for a total volume of 6.4 gallons. There are 4 level sensors at heights of 4 inches, 6 inches, 9.5 inches, and 12 inches which provide discrete liquid level indications to the tool. If the tank level reaches either high-high or low- low level, the tool will alarm for an out of range condition and will stop operating. If water is automatically added to the tank and the total level height meets or exceeds the high-high level, the tool will not resume operation until the tank is drained below high-high. Controls to fill and empty the EKC tank reside in the EKC tool. Since there is no analog liquid level measurement device, the tool must give permission to run only after filling or draining the tank to the high level location. Figure Z-4 indicates the required spacing of 3.5 inches between High and High-High in order to never activate the High-High alarm under all possible water additions.
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Figure Z-3, EKC tank drawing46
Logic Programming with RSLogix 500
Allen-Bradley RSLogix 500 software is used to program the MicroLogix series of controllers via a ladder logic method. The Allen-Bradley Micrologix Programmable Controllers Instruction Set Reference Manual was referenced for the design.[14] The PLC will evaluate each rung of the ladder and proceed through the rung if the conditions encountered are true. The PLC will carry out instructions that follow true statements. The logic flow is valid, but there are most likely script or addressing errors that will be displayed upon uploading to the PLC. This program will be qualified and debugged by the appropriate ON Semiconductor engineers before implementation. Following is an overview of the 4 basic logic rungs.
In the first rung, the PLC will check for the proper conditions to exist. First, the Emergency stop
switch must not be pressed. Second, the tool must not be operating cleaning wafers. Third, the HMI switch must either be in Automatic mode or the manual start button pressed while the HMI switch is in Manual Mode. There are 6 Examine If Closed (XIC) instructions in figure Z-5. Upon these conditions being met, a PLC output will activate the System Running Light on the HMI via an output energize instruction. At any time if the XIC instruction become false, the System Run Light will turn off.
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Figure Z-4, Ladder Logic Rung One47
In the second rung, the PLC is always receiving a 4-20 milliamp analog signal from the refractometer transmitter. The Scale With Parameters (SCP) instruction specifies that 4 milliamps equals a 0% water concentration, and 20 milliamps equals a 20% water concentration. The instruction places the concentration value into output file location F8:4.
Figure Z-5, Ladder Logic Rung Two
Rung three begins with three XIC instructions. First, the system run light output must be active.
Next, the closed loop recirculation pump must have an operate signal from the tool and flow is proved by a flow input. If the closed loop is not flowing, the refractometer input may not be accurate. In that situation the rung would not continue through XIC 2 and 3 on the rung. Next are 2 Examine If Open (XIO) instructions to halt progress if either the DI water valve output is active, or the recirculation timer is timing (meaning that the system is already adding water or waiting for it to blend). The next instruction is a Less Than (LES) instruction. If the measured water concentration allocated to file F8:4 is less than 17%, the instruction is true and the Adding Water Light output will latch. A latched output will remain energized until a separate unlatch instruction is encountered, even if the conditions preceding the latch instruction on the rung become false. Next, a Move (MOV) instruction places the refractometer value into file location F8:3 so it can be used in the next instruction. The following Compute (CPT) instruction takes the F8:3 refractometer number and calculates the amount of time in seconds required for the DI water valve to be open to dose the required water into the tank, and places that number into F8:0. The time value has significant digits to 1/100 of a second.
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Figure Z-6, Ladder Logic Rung Three
Table Z-4, Water Required as a Function of Concentration Used in Rung 3 48
Rung four proceeds if the first XIC instruction is true, meaning the Adding Water Light output
is energized. The next instruction is a One Shot (ONS) instruction. A ONS allows only one false to true transition to occur until the proceeding instruction again changes from a true to false state. Placement of this instruction on the rung ensures the rest of the sequence is only executed one time until the water has been added and mixing time has elapsed. A MOV instruction must be used next to move the calculated time into the next Timer Off Delay (TOF) instruction preset. The DI water valve
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output will be energized from TOF= 0 to TOF= Preset, adding the calculated volume of water to the tank. Next a Timer On Delay (TON) will keep rungs three and four from re-executing for three minutes by timing to 180 seconds before unlatching the Adding Water Light output. See Appendix
Figure Z-7, Ladder Logic Rung Four49
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Management
Qualifications of each individual working on project are as follows: Zacary Shumway: Zacary has an ME education. He is currently employed as an acting Facility Engineer at ON Semiconductor, with ownership of the deionized water system that supplies the required DI water for this project. He has 25 years total working experience in the Semiconductor, Oilfield, and Construction industries. He has experience with ladder logic, PID loops, PLCs, transducers, actuators, semiconductor purity standards, and is capable of integrating control systems. Steven Ferris: Steven has a ME education with design courses in thermal fluid systems. With 7 years of experience as a process operator in an industrial environment, he as a vast knowledge of PLC’s, water loop systems, materials, and is capable of integrating fluid systems. Nouf Alhodaibi: Nouf has a ME education with design courses in thermal fluid systems. With heat transfer, thermodynamic, and fluid flow courses she is capable of optimizing heated fluid systems. Shereen Aljumah: Shereen has a ME education with courses in physics, chemistry, and engineering. She is capable of calibration of refraction indices and percent composition of fluids.50
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Budget
Budget for Alternative 1: Part Quantity Unit price Total cost PTFE pressure regulator 1 $888.89 $953.20 PTFE Tubing 1/2“ 5 ft $17 $23 PTFE Tubing 3/8“ 5 ft $10.70 $16.69 PTFE Fittings 3 $34.47 $116.20 3/8“ Stainless Steel Tubing
2 ft $13.58 $29.44
Refractometer 1 $16100 $16100 MicroLogix 1400 PLC 1 $1920 $2035.20 Malema Flowmeter 1 $600 $600 DI Water Valve 1 $85 $90 Total $19963.73
Final Budget for Alternative 2:51 Part Quantity Unit price Total cost PTFE pressure regulator 1 $888.89 $953.20 PTFE Tubing 1/2“ 5 ft $17 $23 PTFE Tubing 3/8“ 5 ft $10.70 $16.69 PTFE Fittings 3 $34.47 $116.20 3/8“ Stainless Steel Tubing
2 ft $13.58 $29.44
Refractometer 1 $16100 $16100 MicroLogix 1400 PLC 1 $1920 $2035.20 Malema Flowmeter 1 $600 $600 DI Water Valve 1 $85 $90 Eemax DI water preheater
1 $1170.57 $1270.75
Total $21234.48 Budget for Alternative 3:
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Part Quantity Unit price Total cost PTFE pressure regulator 1 $888.89 $953.20 PTFE Tubing 1/2“ 5 ft $17 $23 PTFE Tubing 3/8“ 5 ft $10.70 $16.69 PTFE Fittings 3 $34.47 $116.20 3/8“ Stainless Steel Tubing
2 ft $13.58 $29.44
Refractometer 1 $16100 $16100 MicroLogix 1400 PLC 1 $1920 $2035.20 Malema Flowmeter 1 $600 $600 DI Water Valve 1 $85 $90 Eemax DI water preheater
1 $1170.57 $1270.75
White Knight AP-100 Pump
1 $3500 $3710
Total $24944.48
All installing work will be completed in house at ON Semiconductor so cost for labor was not
included in all budgets.52
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Conclusion
The objective was to design a closed loop system that will continuously monitor the percentage of DI water in EKC, and add water to a holding tank inside the wafer cleaning tool to maintain a 12- 18% water concentration. Adding DI water to the system will extend the bath life of EKC from a current life of 125 cycles up to 400 cycles saving money by: reducing costs of EKC, reducing downtime of tool, and waste reduction.
We have designed a DI water additive system to extend bath life of EKC. EKC is a liquid
chemical that has 18% water content initially. The recipe/run is normally 30 minutes per cycle, EKC is evenly sprayed on the wafers for ~10 minutes inside the process chamber. Water will evaporate during spray cycles reducing the water content in the EKC mixture. After each cycle it is recirculated in the bypass pipeline to keep fluid at temperature. During the bypass time of 20 min water will be added if needed to keep a 12-18% water content.
To modify the system we are going to add a refractometer, PLC, DI water pipeline, pressure regulator, preheater, flow meter, and control valve. The refractometer sensor will determine the water concentration as a refractive index value. This information will be sent to the PLC in a 4-20 mA signal. If the water concentration is below the set point selected the PLC will signal the valve to open for a set time calculated by the PLC based how much water is needed. A preheater will heat the DI water from room temperature to at least 50°C before entering the EKC system to keep the EKC from cooling down. The flow meter will prove flow to the PLC and allow for close monitoring of flow rate.53
Once this design is properly implemented, it will automatically keep the water concentration between 12-18% extending the bath life of EKC. ON Semiconductor will save money on chemical purchase of EKC, tool downtime reduction, and waste handling costs. 54
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References [1] DuPont EKC265 (2018). DuPont Plasmsolv EKC 265 Technical Data Sheet. [Online] Available at: http://www.dupont.com/content/dam/dupont/products-and-services/electronic-and-electrical- materials/documents/ekc/EKC265.pdf [Accessed 20 Apr. 2019]. [2] K-Patent Process Instruments, (2018). PR-33-S Post Etch Residue Removal Using Spray Tool. [Online] Available at: http://www.kpatents.com/assets/files/applications/5.02.04_postetch_residue_removal_using_spray_tool .pdf [Accessed 20 Apr. 2019].
[3] International Polymer Solutions, (2018). Full Catalog. [Online] Available at: https://www.ipolymer.com/pdf/ips-full-catalog.pdf [Accessed 20 Apr. 2019].
[4] Malema, (2018). M-2700 Integrated Ultrasonic Flow Meter. [Online] Available at: http://www.malema.com/m-2700-integrated-ultrasonic-flow-meter [Accessed 20 Apr. 2019].
[5] Fluorostore, (2018). Teflon (PTFE) Tubing. [Online] Available at: https://www.fluorostore.com/collections/ptfe-tubing-collection/products/fractional-metric-ptfe- fluoropolymer-tubing?variant=458719905[Accessed 20 Apr. 2019].
[6] Plumbing Supply, (2018). De-ionized Tankless Commercial Water Heaters. [Online] Available at: https://www.plumbingsupply.com/de-ionized-tankless-water-heaters.html [Accessed 09 Dec. 2018].
[7] White Knight Fluid Handling, (2018). AP Series Pumps. [Online] Available at: https://wkfluidhandling.com/products/pumps/aodb/legacy/ap-series/ [Accessed 09 Dec. 2018].
[8] Allen Bradly, (2018). MicroLogix 1400 Programmable Logic Controller Systems. [Online] Available at: https://ab.rockwellautomation.com/Programmable-Controllers/MicroLogix-1400 [Accessed 09 Dec. 2018].
[9] Mostafa Yahia Elsehamy, (2016). Effect of Deionized Water On Carbon Steel and Stainless Steel. [Online] Available at: https://www.researchgate.net/profile/Mostafa_Yahia/publication/309358216_Effect_of_demineralized_ water_on_carbon_steel_and_stainless_steel/links/580afa7d08ae2cb3a5d305f8/Effect-of-demineralized- water-on-carbon-steel-and-stainless-steel.pdf [Accessed 09 Dec. 2018].
[10] Flowmeters, (2018). Metraflow non invasive flow meter. [Online] Available at: https://www.flowmeters.co.uk/metraflow-non-invasive-pfa-flow-meter-the-perfect-ultra-pure-water- flowmeter/
[11] Katronic, (2018). KATflow 150 flow meter. [Online] Available at: https://katronic.com/fileadmin/katronic/downloads/datasheets/DS_KF150_V41EN_1504.pdf
[12] Thorne and Derrick International, (2019). How transit-time ultrasonic technology works. [Online] Available at: https://www.heatingandprocess.com/manufacturer/micronics-flow-meters/how-transit- time-ultrasonic-flow-meters-work/
[13] Allen-Bradley, (2018). Micrologix Programmable Controllers Manual. [Online] Available at:
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https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1766-um001_-en-p.pdf
[14] Allen-Bradley, (2018). Micrologix Programmable Controllers Instruction Set Reference Manual. [Online] Available at:
https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1766-rm001_-en-p.pdf
[15] Eemax HA013240 HA013 - 1.5 GPM at 60° F Rise - 240V / 1 Ph Tankless Point of Use Water Heater.” EComfort, 2019,[Online] Available at:
.https://www.engineeringtoolbox.com/specific-heat-capacity-water-d_660.html
[16] Eemax HA013240 HA013 - 1.5 GPM at 60° F Rise - 240V / 1 Ph Tankless Point of Use Water Heater.” EComfort, 2019
http://www.eemax.com/wp-content/uploads/2016/08/Sizing-MAP.pdf
[17] What’s Right for Me?,(2019). Eemax HomeAdvantage II.[Online] Available at:
http://www.eemaxha.com/products/whats-right-for-me
[18] Eemax HA013240 HA013 - 1.5 GPM at 60° F Rise - 240V / 1 Ph Tankless Point of Use Water Heater.[Online] Available at:
https://www.ecomfort.com/Eemax-HA013240/p70354.html
[19] Eemax HA013240 HA013 - 1.5 GPM at 60° F Rise - 240V / 1 Ph Tankless Point of Use Water 55Heater.[Online] Available at:
http://www.eemaxha.com/wp-content/uploads/2016/08/Spec-HomeAdvII.pdf
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Appendix56
Gantt Charts And Responsibility Statements pages 53-56
MatLab Code for Thermal Analysis Page 57
Results from Thermal Analysis Page 58
PLC Enclosure Drawings Pages 59-60
PLC Enclosure Specifications Page 61
Fuji 30mm Pilot Devices Specifications Pages 62-67
Selected Allen-Bradley Specifications Pages 68-78
RSLogix 500 Ladder Logic Pages 79-82
DI Water Valve Specifications Page 83
PTFE Standard Sizing Page 84
Malema M-2700 Flow Meter Specs Page 85-87
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Gantt Charts and Responsibility statements
Zac Shumway Individual Gantt Chart and Responsibility Statement:
Zac Shumway is responsible for selecting a Programmable Logic Controller, incorporating inputs and outputs as required, writing ladder logic for the system to operate, and designing an enclosure to house the PLC and a Human Machine Interface (HMI). 57
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Steven Ferris Individual Gantt Chart and Responsibility Statement:
Steven Ferris is responsible for fluid flow of the system including: selecting piping material, valve, pressure regulator, flow meter, fittings, input and output designs, fluid dynamics, and generating a bill of materials of the system.58
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Nouf Alhodaibi Individual Gantt Chart and Responsibility Statement:
Nouf Alhodaibi is responsible for the thermal analysis of the project. The thermal aspects go from selecting and sizing a water preheater, computing the time needed to heat the deionized water from room temperature to an intermediate temperature selected for the preheater, and finally computing the overall total time of the whole heating operation.59
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Shereen Aljumah Individual Gantt Chart and Responsibility Statement:
My design responsibilities are : 1- Layout design. 2- Refractometer PR-23GP. 3- Refractometer calibration. 4- Example of relation between refractive index and temperature. 60
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MATLAB Code for Thermal Analysis
Tin=18; Tf=65; P_tank=3000; Int_Temp=20:5:60; T_rise=Int_Temp-Tin; T_riseF=T_rise*9/5+32; %%%%%%% P_preheat=[6 6 7 9 10 12 13 15 16]; P_preheat=P_preheat*1000; Eff=0.998; %% Din=0.546;%[in] L=24; %[in] VolW=pi/4*Din^2*L*0.0164; %[Liters]; rhoW=1; %[kg/l] CpW=4.19e3; %[J/kgK] %% sEKC=1.104; VolT=4; %[gal] VolT=VolT*3.785; %[Liters] CpT=5e3; %[J/kgK] %{3000*20*60/(1.104*1*4*3.785*(65-22))} %% Time_preheat=rhoW*VolW*CpW*T_rise./(Eff.*P_preheat); Ti=0.85*Tf+0.15*Int_Temp; Tip=0.85*Tf+0.15*Tin; Time_tank=sEKC*rhoW*VolT*CpT*(Tf-Ti)./(P_tank); Time_tankp=sEKC*rhoW*VolT*CpT*(Tf-Tip)./(P_tank); Total_Time=Time_preheat+Time_tank; %% fprintf("Intermed Temp \t\t Preheater Time (s) \t\t Tank Time (s) \t\t Total Time (s)\n"); for i=1:length(Int_Temp) fprintf("\t %d \t\t\t\t %.2f \t\t\t\t\t %5.2f \t\t\t\t %5.2f\n", Int_Temp(i), Time_preheat(i), Time_tank(i), Total_Time(i)); end fprintf("\n Heating time without preheater: %.2f seconds \n",Time_tankp);
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Results from Thermal Analysis
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