Background The document will be revised for its five year review and updated per the committee agreed upon changes.

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1 Background Statement for SEMI Draft Document 5643 Revision to SEMI C , SPECIFICATIONS AND GUIDELINES FOR SULFURIC ACID with title change to: SPECIFICATION AND GUIDE FOR SULFURIC ACID 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. Notice: Additions are indicated by underline and deletions are indicated by strikethrough. Background The document will be revised for its five year review and updated per the committee agreed upon changes. Ballot Adjudication Information Task Force Review Committee Adjudication Group: Analytical Methods TF NA Liquid Chemicals Committee Date: Wednesday, November 6, 2013 Wednesday, November 6, 2013 Time & Timezone: 10:00 AM to 12:00 Noon (PST) 1:00 PM to 4:00 PM (PST) Location: SEMI Headquarters SEMI Headquarters City, State/Country: San Jose, CA / USA San Jose, CA / USA Leader(s): Frank Parker / ICL Frank Flowers / FMC Frank Parker / ICL Frank Flowers / FMC Standards Staff: Michael Tran mtran@semi.org Michael Tran mtran@semi.org This meeting s details are subject to change, and additional review sessions may be scheduled if necessary. Contact 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.

2 SEMI Draft Document 5643 Revision to SEMI C , SPECIFICATIONS AND GUIDELINES FOR SULFURIC ACID with title change to: SPECIFICATION AND GUIDE FOR SULFURIC ACID 1 Purpose 1.1 The purpose of this document is to standardize requirements for sulfuric acid used in the semiconductor industry and testing procedures to support those standards. Test methods have been shown to give statistically valid results. Alternative methods may be used as long as they comply with SEMI C1 requirements for method validation. This document also provides a guidelines for grades of sulfuric acid for which a need has been identified. In the case of these grades guidelines, the test methods may not have been statistically validated yet. 2 Scope 2.1 The scope of this document is all grades of sulfuric acid used in the semiconductor industry. NOTICE: This standard does not purport to address safety issues, if any, associated with its use. It is the responsibility of the users of this standard to establish appropriate safety and health practices and determine the applicability of regulatory or other limitations prior to use. 3 Limitations 3.1 None. 4 Referenced Standards and Documents 4.1 SEMI Standard and Safety Guidelines SEMI C1 Guide for the Analysis of Liquid Chemicals SEMI C27 Specification and Guide for Hydrochloric Acid SEMI C35 Specification and Guide for Nitric Acid 4.2 ASTM Standard 1 ASTM D5127 Standard Guide for Ultra Pure Water Used in the Electronics and Semiconductor Industry NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions. 5 Terminology 5.1 None. 6 Physical Propertiesy (for information only) 7 Requirements Table 1 Properties of Sulfuric Acid Chemical Formula H 2 SO 4 CAS No Density at 25 C 1.83 g/ml 7.1 The requirements for sulfuric acid for Grades 1 and 2 and suggested values for Tiers B and C are listed in Table American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania , USA. Telephone: ; Fax: ; Page 1

3 8 Grade 1 Procedures NOTE 1: Alternative methods may be used as long as they comply with SEMI C1 requirements for method validation Each laboratory is responsible for verifying the validity of the method within its own operation. 8.1 Assay Accurately weigh 1 ml of sample in a small glass-stoppered conical flask. Cautiously add 30 ml of water, cool, add 0.1 ml of methyl orange indicator solution (see SEMI C1), and titrate with standardized 1.0 N sodium hydroxide to a red to yellow color change. %Assay ml N of NaOH Weight Mass of sample g 8.2 Color Dilute 2.0 ml of platinum-cobalt stock solution (APHA No. 500; see SEMI C1) to 100 ml with water. Compare this standard (APHA No. 10) with 100 ml of sample in Nessler tubes. View vertically over a white background. The sample must shall be no darker than the standard. 8.3 Chloride Place 40 ml of water in each of two beakers. To one, add carefully 27 ml (50 g) of sample and to the other, 27 ml (50 g) of chloride-free sulfuric acid and mg of chloride ion (Cl). Cool to room temperature and add 1 ml of nitric acid and 1 ml of silver nitrate reagent solution [SEMI C1]. Mix well; if necessary, make the volume of each solution identical by adding water. After 10 minutes, measure the turbidity of each solution using a suitable nephelometer. The turbidity in the sample should shall be no greater than the standard. NOTE 1:NOTE 2: Prepare chloride-free sulfuric acid in a hood by gently fuming sulfuric acid in a crucible or dish for at least 30 minutes. Cool and transfer to a tightly-capped glass bottle for storage. 8.4 Nitrate Prepare the following solutions: Sample Solution A: Cautiously add 27 ml (50 g) of sample to 1.0 ml of water, dilute to 50 ml with brucine sulfate reagent solution and mix. Control Solution B: Cautiously add 27 ml (50 g) of sample to 1.0 ml of the standard nitrate solution containing 0.01 mg of nitrate ion (NO 3 ) per ml, dilute to 50 ml with brucine sulfate reagent solution and mix. Blank Solution C: Use 50 ml of brucine sulfate reagent solution Heat the three solutions in a preheated (boiling) water bath for 10 minutes. Cool rapidly in an ice bath to room temperature. Set a photometer at 410 nm and, using 1 cm cells, adjust the instrument to read zero absorbance with Blank Solution C in the light path, then determine the absorbance of Sample Solution A. Adjust the instrument to read zero absorbance with Sample Solution A in the light path and determine the absorbance of Control Solution B. The absorbance of Sample Solution A should shall be no greater than that Control Solution B. 8.5 Phosphate Evaporate 11 ml (20 g) of sample to dryness in a platinum dish in a hood. Dissolve the residue in 25 ml of 0.5 N sulfuric acid. Add 1 ml of ammonium molybdate reagent solution (see SEMI C1) and 1 ml p-(methylamino)phenol sulfate reagent solution (see SEMI C1). Allow to stand at room temperature for 2 hours. Any blue color produced should shall be no greater than that produced when 0.01 mg of phosphate ion (PO 4 ) (see SEMI C1) is treated as the sample. 8.6 Arsenic and Antimony (as As) To 109 ml (200 g) of sample in a beaker, add 5 ml of nitric acid and evaporate to about 10 ml in a hood. Cool. Cautiously add 10 ml of water, and again evaporate to about 5 ml. Cool, and cautiously wash into a generator flask with water to make a volume of 35 ml. Proceed as described in General Method for Arsenic (and Antimony) in SEMI C1, starting with the sentence which begins: Swirl the flask... Any red color in the silver diethyldithiocarbamate solution from the sample should shall be no greater than that of the standard containing mg of arsenic (As) (see SEMI C1). Page 2

4 8.7 Trace Metal Analysis The following method has given satisfactory results in determining trace metal impurities at the value specified for each of the following trace metals: aluminum (Al), boron (B), calcium (Ca), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), magnesium (Mg), manganese (Mn), nickel (Ni), potassium (K), sodium (Na), tin (Sn), titanium (Ti), and zinc (Zn). Alternative methods may be used as long as appropriate method validation as per SEMI C1 can be demonstrated Special Reagents Water The water used for all the dilution, calibration and standards should meet at a minimum the criteria for Type E1.1 in ASTM D5127 in regard to cation analysis Indium Internal Standard Make up the indium internal standard solution to a concentration of 20 µg/ml (ppm) from the appropriate concentrated indium standard solution Nitric Acid, Ultrapure (SEMI C35, Grade 2) Use nitric acid specified for ultra low metal ion content % Nitric Acid Solution Dilute 20 ml of SEMI C35, Grade 2 ultrapure nitric acid (see ) to 1 L using water meeting the criteria for Type E1.1 in ASTM D Hydrochloric Acid (SEMI C27, Grade 2) Ultrapure Use hydrochloric acid specified for ultra low metal ion content Sample Preparation Boron In a clean environment, dilute 1.00 g sample with 15.0 g of Type E1.1 water and add 15 µl of the indium internal standard. Run a reagent blank Tin In a clean environment, place 100 g of sulfuric acid in a quartz crucible. Slowly evaporate to dryness on a hot plate avoiding loss of sample by effervescence or spattering. Cool. Add 2 ml of high purity 12 M hydrochloric acid (see ) and 10 ml of water. Cover, and digest on the hot plate for 10 minutes. Cool. Transfer quantitatively to a 50 ml volumetric flask using water for rinsing and dilution to volume. Run a reagent blank All Other Elements In a clean environment, place 100 g of sulfuric acid in a quartz crucible. Slowly evaporate on a hot plate avoiding loss of sample by effervescence or spattering until approximately 2 ml of liquid remains. Cool. Add carefully, 1 ml of high purity, 70% nitric acid (see ). While maintaining volume, carefully warm several minutes to dissolve any residue. Cool. Transfer quantitatively to a 50 ml volumetric flask using 2% nitric acid (see ) and dilute to volume. Run a reagent blank Analysis Using the prepared solutions and blanks, analyze boron by inductively coupled plasma mass spectrometry (ICP/MS). Using the acid sample and reagent blank, analyze sodium, calcium, iron and potassiumggroup I elements by flame atomic absorption spectroscopy. Analyze all other elements by plasma emission spectroscopy. NOTE 2:NOTE 3: Analysis of dilute sulfuric acid can produce rapid corrosion of nickel cones commonly used in inductively coupled plasma mass spectrometry, platinum cones should be considered as alternative when performing this analysis. 9 Grade 2 Procedures NOTE 3:NOTE 4: Alternative methods may be used as long as they comply with SEMI C1 requirements for method validation Each laboratory is responsible for verifying the validity of the method within its own operation. 9.1 Non-Metal Impurities See 8, which contains procedures for the following tests: Assay Color (APHA) Chloride Nitrate Phosphate 9.2 Trace Metals Analysis Page 3

5 9.2.1 The following method has given satisfactory results in determining metal ion impurities at the values specified for each of the following metals: aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), boron (B), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), lithium (Li), magnesium (Mg), manganese (Mn), nickel (Ni), potassium (K), sodium (Na), tin (Sn), titanium (Ti), vanadium (V), and zinc (Zn). Alternative methods may be used as long as appropriate method validation as per SEMI C1 can be demonstrated Special Reagents Nitric Acid, (SEMI C35, Grade 2) Ultrapure Use nitric acid specified for low metal ion content % Nitric Acid Solution Dilute 10 ml of SEMI C35, Grade 2 ultrapure nitric acid (see ) to 1 L using water meeting the criteria for Type E1.1 in ASTM D5127 with regards to metal content Water The water used for all the dilution, calibration and standards should meet at a minimum the criteria for Type E1.1 in ASTM D5127 in regard to cation analysis Indium Internal Standard Make up the indium internal standard solution to a concentration of 20 g/ml (ppm) from the appropriate concentrated indium standard solution Sample Preparation Chromium, Lithium, Manganese, Nickel, Titanium, Vanadium, and Zinc In a clean environment, place 1.00 g of sample into a clean quartz dish. Slowly evaporate on a hot plate to dryness avoiding loss of sample by effervescence or spattering. Dissolve the residue with 5 ml of the 1% nitric acid solution (see ) by heating on a hot plate at low temperature for several minutes. Cool to room temperature, dilute to 15 ml with 1% nitric acid (see ), add 15 μl of the indium internal standard, mix well. Run a reagent blank All Other Elements In a clean environment, dilute 1.00 g sample with 15.0 g of Type E1.1 water and add 15 μl of the indium internal standard. Run a reagent blank Analysis Using the prepared solutions and blanks, analyze sodium, potassium, calcium and iron by graphite furnace atomic absorption (GFAA) and the remaining elements by inductively coupled plasma mass spectrometry (ICP/MS). For calibration, the standards are made up with the 1% nitric acid solution (see ) and the indium internal standard such that the final indium concentration is 20 ng/g. For boron and tantalum, the standards for calibration must be matrix matched with equal amounts of sulfuric acid certified to have both elements below 1 g/ml in the concentrated acid. NOTE 4:NOTE 5: Analysis of dilute sulfuric acid can produce rapid corrosion of nickel cones commonly used in inductively coupled plasma mass spectrometry, platinum cones should be considered as alternative when performing this analysis. 10 Grade 3 Procedures 10.1 This section does not apply to this chemical. 11 Grade 4 Procedures 11.1 This section does not apply to this chemical. 12 Grade 5 Procedures 12.1 This section does not apply to this chemical. 13 Tier A Procedures 13.1 This section does not apply to this chemical. 14 Tier B Procedures 14.1 Standardized test methods are being developed for all parameters at the purity levels indicated. Until standardized test methods are published, test methodology shall be determined by user and producer. The Liquid Chemicals Committee considers a test method to be valid only if method validation according to SEMI C1 can be demonstrated. Page 4

6 15 Tier C Procedures 15.1 Standardized test methods are being developed for all parameters at the purity levels indicated. The Liquid Chemicals Committee considers a test method to be valid only if method validation according to SEMI C1 can be demonstrated. 16 Tier D Procedures 16.1 This section does not apply to this chemical. Table 2 Impurity Limits, Suggested Values and Other Requirements for Sulfuric Acid Previous SEMI Reference # SEMI C SEMI C SEMI C Grade 1 Grade 2 Tier B Tier C (Specification) (Specification) (Guideline) (Guideline) Assay (H 2 SO 4 ) 95.0% 97.0% 95.0% 97.0 % 95.0% 97.0% 95.0% 97.0% Color (APHA) 10 max. 10 max. 10 max. 10 max. Chloride (Cl) 0.1 ppm max. 100 ppb max. 50 ppb max. 50 ppb max. Nitrate (NO 3 ) 0.2 ppm max. 200 ppb max. 100 ppb max. 100 ppb max. Phosphate (PO 4 ) 0.5 ppm max. 500 ppb max. 100 ppb max. 100 ppb max. Aluminum (Al) 0.2 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Antimony (Sb) -- 5 ppb max. 1 ppb max. 100 ppt max. Arsenic (As) ppb max. 1 ppb max. 100 ppt max. Arsenic and Antimony (as As) ppm max Barium (Ba) ppb max. 1 ppb max. 100 ppt max. Boron (B) 0.02 ppm max. 20 ppb max. 1 ppb max. 100 ppt max. Cadmium (Cd) ppb max. 1 ppb max. 100 ppt max. Calcium (Ca) 0.3 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Chromium (Cr) 0.2 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Copper (Cu) 0.1 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Iron (Fe) 0.2 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Lead (Pb) 0.3 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Lithium (Li) ppb max. 1 ppb max. 100 ppt max. Magnesium (Mg) 0.3 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Manganese (Mn) 0.2 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Nickel (Ni) 0.1 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Potassium (K) 0.3 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Sodium (Na) 0.3 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Tin (Sn) 0.2 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Titanium (Ti) 0.3 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Vanadium (V) ppb max. 1 ppb max. 100 ppt max. Zinc (Zn) 0.2 ppm max. 10 ppb max. 1 ppb max. 100 ppt max. Particles in bottles: (size, #/ml) (See #1 ) (See #1 ) (See #1 ) (See #1 ) #1 Due to the limitations of current particle counters, particle size and number are to be agreed upon between supplier and user. See SEMI C1 in the section of Calibration and Measurement Method for Particles in Liquids. Page 5

7 NOTICE: (SEMI) makes no warranties or representations as to the suitability of the Standards and Safety Guidelines set forth herein for any particular application. The determination of the suitability of the Standard or Safety Guideline 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. Standards and Safety Guidelines are subject to change without notice. By publication of this Standard or Safety Guideline, SEMI takes no position respecting the validity of any patent rights or copyrights asserted in connection with any items mentioned in this Standard or Safety Guideline. Users of this Standard or Safety Guideline 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 6