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1 Background Statement for SEMI Draft Document 5609 REVISION OF SEMI C SPECIFICATION FOR SULFUR HEXAFLUORIDE (SF 6 ) IN CYLINDERS, 99.97% QUALITY 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 This standard is due for 5-year review. The TF discussed the additional technique of FTIR for the Hydrogen Fluoride specification is needed. In addition, the removal of name brand instrumentation to more generic terms and techniques for the Hydrogen Fluoride specification is needed. Also, additional changes are needed to conform with the SEMI Procedure Guide. Review and Adjudication Information Task Force Review Committee Adjudication Group: Gases Specifications Task Force NA Facilities & Gases Committees Date: Monday, October 28, 2013 Tuesday, October 29, 2013 Time & TBD 9:00 AM- Noon Timezone: Location: SEMI HQ SEMI HQ City, San Jose, CA San Jose, CA State/Country: Leader(s): Mark Ripkowski (CONSCI) Tim Volin (Parker Hannifin) Mohamed Saleem (Fujikin) Steve Lewis (CH2M Hill) Standards Staff: Kevin Nguyen, knguyen@semi.org Kevin Nguyen, knguyen@semi.org 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. Note: Additions are indicated in red and deletions are indicated by strikethrough.

2 SEMI Draft Document 5609 REVISION OF SEMI C SPECIFICATION FOR SULFUR HEXAFLUORIDE (SF 6 ) IN CYLINDERS, 99.97% QUALITY 1 Purpose 1.1 The purpose of this document is to provide specifications for sulfur hexafluoride (SF 6 ) that is used in the semiconductor industry. 2 Scope 2.1 This document covers requirements for sulfur hexafluoride used in the semiconductor industry. 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 documents to establish appropriate safety and health practices, and determine the applicability of regulatory or other limitations prior to use. 3 Description 3.1 Sulfur hexafluoride is colorless and odorless. It is noncombustible and has a low toxicity. It is shipped as a liquefied gas under its own vapor pressure. 4 Limitations 4.1 None. 5 Referenced Standards and Documents 5.1 SEMI Standard SEMI C3 Specifications for Gases NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions. 6 Terminology 6.1 Terminology appropriate to this standard is defined in SEMI C3. 7 Requirements 7.1 Purity and other requirements for sulfur hexafluoride are given in Table 1. Table 1 Impurity and Other Requirements for Sulfur Hexafluoride Purity 99.97% Impurities Maximum Acceptable Level (ppm) (See #1 ) Air 100 Carbon Tetrafluoride (CF 4 ) 100 Hydrogen Fluoride (HF) 1 Water (H 2 O) (mol/mol) 8 TOTAL LISTED IMPURITIES 209 #1 An analysis of significant figures has not been considered. The number of significant figures will be based on analytical accuracy and the precision of the provided procedure. Page 1 Doc SEMI

3 8 Physical ConstantsProperties of Sulfur Hexafluoride (for information only) Table 2 Properties of Sulfur Hexafluoride Metric Units US Units CAS # Molecular weight Boiling point at 1 atm 63.7 C 82.7 F Density of gas at 20 C (68 F) and 1 atm Specific gravity of gas at 21.1 C (70 F) and 1 atm (air = 1) kg/m lb/ft Density of liquid at 50 C 1910 kg/m lb/ft 3 9 Analytical ProceduresTest method for determining impurity limits (Notes 1, 2, and 3) 9.1 Air and Carbon Tetrafluoride This procedure method is for the determination of air and carbon tetrafluoride using a gas chromatograph with a thermal conductivity detector Detection Limit 1 ppm (mol/mol) Instrument Parameters Column: 2.4 m (8 ft) by 6.4 mm (1/4 in) OD, 5.1 mm (0.201 in) ID stainless steel tubing packed with Porapak Q (80/100 mesh) or equivalent Carrier Flow: 30 ml/min helium Sample Volume: 1 ml Temperatures: Detector 110 C Column 70 C Calibration Standards ppm (mol/mol) carbon tetrafluoride, ppm (mol/mol) Air (O 2 /N 2 blend), balance helium Operating Procedure Inject the calibration standard. Analyze the standard using the conditions described above. Record the retention times and peak areas Inject the sample to be tested in the same manner as the calibration standard. Record the retention times and peak areas Repeat Calculate the concentrations of air and carbon tetrafluoride in the sample, using the formula below. The result may not exceed the specification in Table 1 of this Standard. Sample Peak Area Standard Peak Area Concentration of Standard = Concentration of Sample (1) Page 2 Doc SEMI

4 9.2 Hydrogen Fluoride This procedure method is for the determination of hydrogen fluoride by quantitative collection in dilute sodium bicarbonate (NaHCO 3 ) and subsequent analysis by ion chromatography. (or FTIR (Fourier Transform Infrared) Spectroscopy. Follow same steps as in 9.3. See note 6.) Detection Limit 0.1 ppm for the method Equipment Required: 500 ml Greenburgh impinger 50 ml Class A pipet Type 316 stainless steel delivery system 5 Fluorocarbon tubing, ¼ in. OD by 0.03 in. wall Reagent Grade sodium bicarbonate Deionized water 50 ml high-density polyethylene bottles Assorted Class A volumetric flasks Ion chromatograph Anion column which separates: F -, Cl -, Br -, SO 4-2, PO Ion Chromatograph Parameters Table 3 Ion Chromatograph Parameters Instrument: Integrator: Dionex 2000 (or equivalent) Dionex 4270 (or equivalent) Analytical Column: HDIC AS4A (or equivalent)see #1 Eluent: M Na 2 CO M NaHCO 3 Flow Rate: Pressure: Detector Conductivity Range: 2 ml/minute 960 psia 3.0 microsiemens for less than 10 ppm Sample: 100 microliters #1 The Analytical Column is composed of 15 micron polystyrene/divinylbenzene substrate agglomerated with anion exchange latex that has been completely aminated. The 0.5% cross-linked latex particles have a diameter of approximately mm and carry the ion exchange sites. The ion exchange capacity of the 4 x 250 mm analytical column is 20 meq/column. The column is stable between ph 0 and 14. The latex particles are strongly held to the substrate surface by electrostatic and van der Waals interactions. Even 4 M NaOH does not break the bond between the latex and the substrate Calibration Calibrate the ion chromatograph by dissolving a weighed amount of ammonium fluoride (NH 4 F) in deionized water and sequentially diluting it to a fluoride concentration of 0.1 ppmw in Class A volumetric flasks and analyzing it as specified by the instrument manufacturer Operating Procedure Prepare a fresh solution of 1.7 mm sodium bicarbonate in deionized water Pipet 200 ml of the solution into a 500 ml Greenburgh impinger Bubble approximately 20 L of sulfur hexafluoride (SF 6 ) through the solution, using the delivery system shown in Figure Analyze the solution as specified by the instrument manufacturer Calculation Calculate the concentration of hydrogen fluoride (HF) using the following formula: Page 3 Doc SEMI

5 where: ppmv HFg = (F- ppmw) Vg mg F - ppm = Fluoride concentration in trapped solution. Vg mg = Volume of collection solution (ml). = Moles of SF 6 bubbled through the collecting solution = Molecular weight of F -. The result may not exceed the specification in Table 1 of this Standard. 9.3 Water This procedure method is for the determination of trace moisture (water) in sulfur hexafluoride using a continuous flowing electrolytic hygrometer or FTIR (Fourier Transform Infrared) Spectroscopy. (See Notes 4, 5, and 56.) Detection Limit 1.0 ppm (vol/vol) or 76 C ( 105 F) Sample Pressure and Flow Set in accordance with instrument manufacturer s instructions Operation Check Check the instrument periodically for correct operation. A gas containing a known amount of moisture should be passed through the instrument. Agreement between the hygrometer instrument and the standard should be within their relative accuracies Operating Procedure Obtain a continuous flow sample of sulfur hexafluoride source, using a clean, electropolished or passivated stainless steel line which has been purged dry after exposure to ambient moisture. (See Note 5.) After prepurging with a dry gas, allow the sample gas to flow through the sampling system and hygrometer instrument until a stable reading is obtained. The reading may not exceed the specification in Table 1 of this Standard. NOTE 1: Introduce the calibration standard as many times as necessary to achieve the desired precision. NOTE 2: All gases used in the analysis of the sample should not contain more than 10% of the specified value of the component of interest, unless otherwise stated. NOTE 3: Observe proper safety procedures for handling and disposing of sulfur hexafluoride (SF 6 ). NOTE 4: The sampling system and hygrometer must be designed to operate at the sample pressure, or the sample pressure must be reduced (by a regulator with a diaphragm of stainless steel or other suitable material) to accommodate the pressure restrictions of the hygrometer. NOTE 5: A passivation procedure is described in Metals Handbook, Eighth Edition, Volume 2, ASM International, Metals Park, Ohio. NOTE 6: An FTIR spectrometer is an infrared spectrometer in which a Michelson Interferometer is used in place of a grating or prism. The simplicity of the Michelson Interferometer, with only one moving part, an oscillating mirror, along with a He-Ne laser as a reference, provides nearly absolute frequency accuracy. This translates into a high spectral resolution. FTIR has greater detection efficiency since the energy-wasting slits required for dispersive spectrometers are not used. With a microcomputer to control the functions and to perform data processing, signal averaging is used to improve the signal-to-noise ratio. All these features lead to good reproducibility and rapid measurement results compared with conventional IR techniques. (2) Page 4 Doc SEMI

6 Figure 1 Test Setup NOTICE: SEMI makes no warranties or representations as to the suitability of the standard(s) set forth herein for any particular application. The determination of the suitability of the standard(s) is solely the responsibility of the user. Users are cautioned to refer to manufacturer s instructions, product labels, product data sheets, and other relevant literature respecting any materials or equipment mentioned herein. These standards are subject to change without notice. By publication of this standard, (SEMI) takes no position respecting the validity of any patent rights or copyrights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of any such patent rights or copyrights, and the risk of infringement of such rights are entirely their own responsibility. Page 5 Doc SEMI