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Background Statement for SEMI Draft Document 3440C
NEW STANDARD: TEST METHOD FOR PRESSURE TRANSDUCERS IN GAS DELIVERY SYSTEMS
Notice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this Document.
Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, “patented technology” is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided.
Background
There are currently no standardized test methods or specifications for pressure measurement devices (transducers and gauges) used in semiconductor process equipment and facilities distribution systems. There are documents from ASME and ISA that can be readily adapted for use in this industry that will allow the users of these devices to clearly and competitively analyze the performance characteristics from the different manufacturers. The rated accuracy needs to be clearly defined as well as the design characteristics of these critical components. This activity is similar to those already underway in the Facilities Committee for MFCs, valves, and regulators.
Additionally, the Facilities & Gases Committee has addressed the physical dimensions and interfaces of pressure transducers in the Gas Box Components Task Force as well as the Surface Mount Task Force, the envelope dimensions for pressure gauges has not been address and could be an additional activity for this task force.
Document 3440Bwas balloted in Cycle 2 of 2016 and failed due to a persuasive reject. Document 3440C incorporated all negatives and comments and is being issues for Cycle 4 of 2016 for review at the next meeting.
Review and Adjudication Information
Task Force Review / Committee AdjudicationGroup: / Pressure Measurement Task Force / Facilities & Gases NA TC Chapter
Date: / July 11, 2016 / July 12, 2016
Time & Timezone: / 14:00 – 16:00 PDT / 9:00 AM –12:00 Noon PDT
Location: / San Francisco Marriott Marquis
780 Mission St.
San Francisco, CA 94103 / San Francisco Marriott Marquis
780 Mission St.
San Francisco, CA 94103
City, State/Country: / San Francisco, CA/USA / San Francisco, CA/USA
Leader(s)/Authors: / Yanli Chen (UCT)
Jeff Christian (WikaInstrument) / Mohamed Saleem (Fujikin)
Steve Lewis (LPCiminelli)
Standards Staff: / Laura Nguyen ( ) / Laura Nguyen ( )
This meeting’s details are subject to change, and additional review sessions may be scheduled if necessary. Contact the task force leaders or Standards staff for confirmation.
Telephone and web information will be distributed to interested parties as the meeting date approaches. If you will not be able to attend these meetings in person but would like to participate by telephone/web, please contact Standards staff.
Check on calendar of event for the latest meeting schedule.
SEMI Draft Document 3440C
NEW STANDARD: TEST METHOD FOR PRESSURE TRANSDUCERS USED IN GAS DELIVERY SYSTEMS
1 Purpose
1.1 The purpose of this Document is to outline the test methods for electronic pressure transducers used in gas delivery systems for semiconductor processing.
2 Scope
2.1 This Document describes the procedures for testing the leak integrity, warm up time, voltage sensitivity, inaccuracy, linearity, repeatability, hysteresis, reproducibility, thermal coefficient, drift, accelerated life cycle, and proof pressure of pressure transducers with a full pressure range of 2757.9 KPa (400 psia) or less in gas delivery systems.
NOTICE:SEMI Standards and Safety Guidelines do not purport to address all safety issues associated with their use. It is the responsibility of the users of the Document to establish appropriate safety and health practices, and determine the applicability of regulatory or other limitations prior to use.
3 Limitations
3.1 This Document does not cover the testing of absolute pressure measurement instruments, pressure switches or mechanical pressure gauges, such as Bourdon tube pressure gauges.
4 Referenced Standards and Documents
4.1 SEMI Standards and Safety Guidelines
SEMI C59 — Specifications and Guidelines for Nitrogen
SEMI E27 — Standard for Mass Flow Controller and Mass Flow Meter Linearity
SEMI E28 — Guide for Pressure Specification of the Mass Flow Controller
SEMI E49 — Guide for High Purity and Ultrahigh Purity Piping Performance, Subassemblies, and Final Assemblies
SEMI E56 — Test Method for Determining Accuracy, Linearity, Repeatability, Short-Term Reproducibility, Hysteresis, and Dead Band of Thermal Mass Flow Controllers
SEMI E89 — Guide for Measurement System Analysis (MSA)
SEMI F1 — Specification for Leak Integrity of High-Purity Gas Piping Systems and Components
SEMI F62 — Test Method for Determining Mass Flow Controller Performance Characteristics from Ambient and Gas Temperature Effects
4.2 American National Standard[1]
ANSI/ISA-S51.1-1979 (R1993) — Process Instrumentation Terminology
4.3 IEC Standard2
IEC 61298-2 — Process Measurement and Control Devices-General Methods and Procedures for Evaluating Performance – Part 2: Tests under Reference Conditions
IEC 61298-3 — Process Measurement and Control Devices-General Methods and Procedures for Evaluating Performance – Part 3: Tests for the Effects of Influence Quantities
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
5 Terminology
5.1 Abbreviations and Acronyms
5.1.1 BFSL—best-fit straight line
5.1.2 DUT— device under test
5.1.3 FS—full scale
5.1.4 Te— the temperature of the environmental chamber
5.1.5 TCzero— the thermal coefficient at zero
5.1.6 TCspan— the thermal coefficient across the span range
5.1.7 Tmin— minimumoperating temperature specified by the DUT manufacturer
5.1.8 Tmax—maximum operating temperature specified by the DUT manufacturer
5.1.9 Vmin— minimum voltage supply specified by the DUT manufacturer
5.1.10 Vmax— maximum voltage supply specified by the DUT manufacturer
5.2 Definitions
5.2.1 absolute pressure — the pressure measured relative to zero pressure (perfect vacuum). [SEMI E28]
5.2.2 accelerated life cycle test — the process by which the device under test is subjected to cycles between its minimum and maximum rated full scale range.
5.2.3 best-fit straight line — the line positioned by minimizing the sum of the squares of the differences between the measurement values and the ideal values.
5.2.4 drift— the change in output over a specified time period for a constant pressure input under specified reference operating conditions. [SEMI E56]
5.2.5 gauge pressure — the pressure measured relative to ambient pressure. For example, when the pressure within a system equals the prevailing ambient pressure, the gauge pressure equals zero.
5.2.6 hysteresis— the difference between the output readings of a pressure transducer when the same pressure is applied consecutively, under the same conditions but coming from opposite (ascending and descending) directions. [SEMI E56]
5.2.7 inaccuracy — the greatest deviation (absolute value) of any measured value from the ideal value for increasing and decreasing inputs for any test cycle separately, and reported in percent of output span or in percent of reading. [IEC 61298-2]
NOTE 1:When testing devices for inaccuracy, best results will be achieved when using a test device traceable to a national standards lab, such as National Institute of Standard Technologies (NIST). The device shall have a relative inaccuracy of at least 4 to 1 with respect to the DUT.
5.2.8 input voltage sensitivity— the change in output value across the range of the input voltage.
5.2.9 leak integrity— the leak measured between the wetted surface volume and the ambient environment surrounding the device. [SEMI F1]
5.2.10 linearity— the closeness to which a curve approximates a straight line. It is measured as a non-linearity and expressed as a linearity. [SEMI E27, SEMI E56]
5.2.11 operating range — the range of operating conditions within which a device is designed to operate and for which operating conditions are stated. [ANSI/ISA S51.1, SEMI E56]
5.2.12 pressure standard — a device used to measure the actual test gas pressure through the DUT.
5.2.13 proof pressure— the maximum pressure the device could be subjected to without any permanent damage.
5.2.14 repeatability— the closeness of agreement among a number of measured values at the same pressure set point, under the same operating conditions, operator, apparatus, laboratory and short intervals of time.It is usually measured as a non-repeatability and expressed as repeatability in percent of full scale. [SEMI E56]
NOTE 2:Repeatability specifically refers to the repeatability of an individual transducer, not the repeatability of a group of transducers.
5.2.15 reproducibility — the closeness of agreement among output readings of the different devices when the same pressure set points are applied to them consecutively under the same operating conditions, operator, apparatus, laboratory, during the same test time frame, and approaching from both pressure directions (ascending and descending).
5.2.16 span — the algebraic difference between the upper and lower range values. [SEMI E27]
5.2.17 operating temperature range — The range of ambient temperatures, given by their extremes, within which the transducer is intended to operate; within this range of ambient temperature all tolerances specified for temperature error, temperature error band, temperature gradient error, thermal zero shift and thermal sensitivity shift are applicable.
5.2.18 uncertaintyRSS— It is a parameter that is associated with a measurement and characterizes the dispersion of values that can be reasonably attributed to the object being measured. In this case, it is a calculated value that includes repeatability, linearity, and hysteresis. It is traditionally quantified by the root sum square (RSS) of repeatability, linearity and hysteresis and expressed in percent of full scale. [SEMI E89]
NOTE 3:This is as same as the term ‘accuracyRSS’ which has been widely used by most pressure transducer manufacturers. AccuracyRSS is a misleading term and its use should be discontinued.
5.2.19 warm up time— a period of time that it takes for the device to produce stable output from the time the input power is first applied after the device has been un-powered for a minimum time period of 24 hours.
5.2.20 zero adjustment — a process of adjusting the output of the device under test (DUT) to zero per the manufacturer’s instructions.
6 Apparatus
6.1 Pressure Reference Standard Device — A pressure measurement device that shall havea relative inaccuracy of at least 4 to 1 with respect to the DUT.
6.2 Environmental Chamber—Capable of stable temperature control (±1°C)from at least the minimum rated pressure transducer temperature (Tmin) to the maximum rated pressure transducer temperature (Tmax) plus 10°C.
6.3 Leak Detector
6.4 Power Supply
6.5 Tubing— Cleaned and maintained to have no adverse effect on the test.
6.6 Valves— Capable of unimpaired operation at Tmaxand two times of the maximum operating pressure.
7 Reagents and Materials
7.1 Test Gas—99.9995% nitrogen (Grade 5.5) per SEMI C59
8 Safety Precautions
8.1 All manufacturers’ recommendations shall be followed and noted when testing the unit. Any safety precautions shall be followed.
9 Technical Precautions
9.1 The manufacturer’s specification and instructions for installation and operation must be applied during all testing.
9.2 The mounting position of the device must be in accordance with the manufacturer’s specifications. No external mechanical constraints beyond the manufacturer’s recommended mounting position shall be used.
10 Calibration and Standardization
10.1 The pressure standard used is to be traceable to a recognized national standards lab,such as the US National Institute of Standards and Technology (NIST).
10.2 All measurement devices shall be calibrated and maintained to the manufacturer’s recommendations. Current calibration records shall be maintained.
11 Sampling
11.1 Randomly selected devices shall be sampled in accordance with SEMI E49.
12 Summary of Test Method
12.1 Leak Integrity— This test measures the allowable leak rate from any of the wetted surface area, into the surrounding atmosphere, and is measured as a rate of helium in units of standard Pa·m3/s (atm·cc/s). The device shall be measured following each test for performance and endurance.
12.2 Warm Up Time—Warm up time is the period that a device takes from its initial power-on or after the device has been turned off for an extended time to read accurately.
12.3 Input Voltage Sensitivity— The voltage shall be varied across the specified range of voltages for the DUT while all other major parameters remain constant.
12.4 Inaccuracy— This test shall determine the deviation between a measured value and the expected value of a device. The maximum deviation among all the setpoints will be recorded as the inaccuracy of the device.
12.4.1 Hysteresis—Hysteresis shall be obtained by subtracting the ascending signal value from corresponding descending signal value. The highest valueamong all the tested setpointswill be reported as the hysteresis of the device.
12.4.2 Linearity —The linearity of the device shall be determined to be the maximum difference between the observed value and the best-fit straight line (BFSL).
12.4.3 Repeatability—This test determines the repeatability of an individual device at identical pressures in a number of consecutive cycles. The device will be pressurized at least three consecutive cycles in both of ascending and descending directions.
12.5 Reproducibility— This test shall determine the reproducibility of different devices for the identical pressures. A minimum of four devices shall be tested at the same time.
12.6 Thermal Coefficient— This test shall measure the output changes of the device in response to changes in ambient temperature.
12.7 Accelerated Life Cycle— The device shall be capable of withstanding repeated full scale cycling. The device shall meet its accuracy and leak integrity specifications during and at the end of the life cycle process.
12.8 Proof Pressure— Proof pressure test will determine maximum pressure that can be applied to a device under test while ensuring that the performance of the device is not permanently affected.
13 Test Procedure
13.1 Preparation
13.1.1 Record ambient temperature, pressure units and gas type used for the test.
13.1.2 Record the manufacturer, model number and serial number of the DUT.
13.1.3 Record the full scale range and voltage or current output range of the DUT.
13.2 Leak Integrity
13.2.1 Test in accordance with SEMI F1.
13.3 Warm Up Time
13.3.1 The DUT shall be brand new or have been powered down for a minimum of 24 hours before the start of this test.
13.3.2 Set the temperature of the test environment to 20°C.
13.3.3 Apply power to the DUT.
13.3.4 Make initial zero adjustment to the DUT. Follow the manufacturer’s instructions.
13.3.5 Set pressure to 0%FS and wait until stabilization. Measure and record the signal output of the DUT and the reference device every five minutes for one hour.
13.3.6 Set pressure to 100%FS and wait until stabilization. Measure and record the signal output of the DUT and the reference device every five minutes for one hour.
13.3.7 See Appendix 1 for all calculations.
13.4 Input Voltage Sensitivity
13.4.1 Set the temperature of the test environment to 20°C.
13.4.2 Apply power to the DUT.
13.4.3 Make initial zero adjustment to the DUT. Follow the manufacturer’s instructions, as required.
13.4.4 Apply a pressure setting of 50%FS to the DUT.
13.4.5 Apply the minimum voltage to the DUT as specified in the manufacturer’s manual.
13.4.6 Record the signal outputs of the DUT and the reference device at every 1 minute interval.
13.4.7 Over period of 10 minutes,increase the voltage input to the DUT until the voltage reaches maximum voltage as specified bythe manufacturer.
13.4.8 See Appendix 1 for all calculations.
13.5 Inaccuracy, Linearity, Hysteresis, and Repeatability— During the Inaccuracy, Linearity, and Hysteresis Tests a sample size of at least four devices shall be tested.
13.5.1 Set the temperature of the test environment to 20°C.
13.5.2 Apply power to the DUTs and wait at least 60 seconds.
13.5.3 Make initial zero adjustment to the DUTs. Follow the manufacturer’s instructions.
13.5.4 Adjust the test pressure to 0%FS of the DUTs, wait until the pressure of the system is stabilized, record both the DUTs and reference signal outputs, as shown in Table 1.
13.5.5 Adjust the pressure and record dataup in 10%FS stepsto 100%FS. Continue the adjustment and recording in 10%FS stepsdownfrom 100%FS to 0%FS. Use Table 1 for data collection.
13.5.6 Repeat the ascending and descending cycles at least two times.
13.5.7 See Appendix 1 for all calculations.
13.6 Reproducibility—A minimum of four devices shall be tested for reproducibility. All devices shall be tested simultaneously to reduce testing error.
13.6.1 Set the temperature of the test environment to 20°C.
13.6.2 Apply power to the DUTs.
13.6.3 Make initial zero adjustments to the DUTs. Follow the manufacturer’s instructions.
13.6.4 Increase the pressure from 0%FS to 100%FS in 10%FS steps with a setpoint change occurring every 200 seconds.
13.6.5 Decrease the pressure from 100%FS to 0%FS in 10%FS steps with a setpoint change occurring every 200 seconds.
13.6.6 Record the pressure outputs from the DUTs and the reference ateach setpointfor both ascending and descending pressure directions.
13.6.7 See Appendix 1 for all calculations.
Table 1Data Tabulation for Inaccuracy, Linearity, Repeatability and Hysteresis
Cycle No:Pressure Setpoint
(%FS) / Signal Output of DUT 1 / Signal Output of DUT 2 / Signal Output of DUT 3 / Signal Output of DUT 4 / Reference Output
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
#1Most commonly, the output values of DUTs are voltage or current values. The output of the reference can be either voltage/current or pressure values depending on the type of the reference device used. The output of DUTs and reference shall be consistent for calculation.
13.7 Thermal Coefficient
13.7.1 Apply power to the DUT.
13.7.2 Make initial zero adjustment to the DUT. Follow the manufacturer’s instructions.
13.7.3 The reference device should be outside of the temperature controlled environment.
13.7.4 Set the temperature (Te) of the temperature controlled environment to Tmin.