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Background Statement for SEMI Draft Document 4501A
REVISION OF SEMI C35-0301
SPECIFICATIONS AND GUIDELINE FOR NITRIC ACID
Note: 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.
Note: 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.
SEMI C35-0301 was due for 5 year review. This standard was reviewed by the Analytical Methods TF. The changes were made to bring up to current SEMI guidelines.
This letter ballot will be reviewed by the Analytical Methods Task Force and adjudicated by the Liquid Chemicals Committee at their meetings in Dallas, TX, during the week of 7 April, 2008.
Note: Additions are indicated by underline and deletions are indicated by strikethrough.
This is a draft document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted standard. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone:408.943.6900 Fax: 408.943.7943
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This is a draft document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted standard. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone:408.943.6900 Fax: 408.943.7943
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SEMI Draft Document 4501A
REVISION OF SEMI C35-0301, SPECIFICATIONS AND GUIDELINE FOR NITRIC ACID
These specifications and this guideline were technically approved by the Global Process Chemicals Committee and are the direct responsibility of the North American Process Chemicals Committee. Current edition approved by the North American Regional Standards Committee on October 17, 1999. Initially available at www.semi.org February 2001; to be published March 2001. This document replaces SEMI C1.12, C7.6, and C8.6 in their entirety. Originally published in 1979, 1990, and 1992 respectively; previously published June 1999.
This is a draft document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted standard. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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1 Purpose
1.1 The purpose of this document is to standardize requirements for nitric acid used in the semiconductor industry and testing procedures to support those standards. Test methods have been shown to give statistically valid results. This document also provides guidelines for grades of nitric acid for which a need has been identified. In the case of the guidelines, the test methods may not have been statistically validated yet.
2 Scope
2.1 The scope of this document is all grades of nitric 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.
These standards do not purport to address safety issues, if any, associated with their use. It is the responsibility of the user of these standards to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
3 Limitations
3.1 None.
4 Referenced Standards and Documents
4.1 SEMI Standards
SEMI C1 — Specifications for ReagentsGuide for the Analysis of Liquid Chemicals
4.2 ASTM Standards[1]
ASTM D5127 — Standard Guide for Ultra Pure Water Used in the Electronics and Semiconductor Industry
NOTICE: Unless otherwise indicated, As listed or revised, all documents cited shall be the latest published versionscations of adopted standards.
5 Terminology
5.1 None.
6 Physical Property (for information only)
Chemical Formula / HNO3CAS No. / 7697-37-2
Density at 25°C / 1.42 g/mL
7 Requirements
7.1 The requirements for nitric acid for Grades 1 and 2 and Tier B are listed in Table 1.
8 Grade 1 Procedures
NOTE 1: Each laboratory is responsible for verifying the validity of the method within its own operation.
8.1 Assay — Accurately weigh a small glass-stoppered conical flask containing about 15 mL of water. Deliver from a pipet about 2 mL of the sample near the water surface, stopper immediately, cool, and reweigh. Dilute to about 50 mL with water, add 0.10 mL of methyl orange indicator solution, and titrate with standardized 1 N sodium hydroxide to a red to yellow color change.
8.2 Color — Dilute 2.0 mL of platinum-cobalt stock solution (APHA No. 500) 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 be no darker than the standard.
8.3 Chloride — Dilute 84 mL (120 g) of sample with 10 mL of water, add 1 mL of silver nitrate reagent solution (SEMI C1), and evaporate to dryness on a steam bath in a hood. Dissolve the residue in 0.5 mL of ammonium hydroxide, dilute with 20 mL of water, and add 1.5 mL of nitric acid. Any turbidity produced should be no greater than that produced when 0.01 mg of chloride ion (Cl) is treated as the sample.
8.4 Phosphate — To 35 mL (50 g) of sample add 10 mL of sodium carbonate reagent solution (SEMI C1) and evaporate to dryness on a steam bath in a hood. Dissolve the residue in 25 mL of 0.5 N sulfuric acid. Add 1 mL of ammonium molybdate reagent solution and 1 mL of p-(methylamino)phenol sulfate reagent solution. Allow to stand at room temperature for 2 hours. Any blue color produced should be no greater than that produced when 0.01 mg of phosphate ion (PO4) is treated as the sample.
8.5 Sulfate — To 70 mL (100 g) of sample add 10 mL of sodium carbonate reagent solution and evaporate to dryness in a hood. Dissolve the residue in 10 mL of water and 1 mL of dilute hydrochloric acid (1 + 19); filter if necessary. Add 1 mL of barium chloride reagent solution, mix, and allow to stand for 10 minutes. Any turbidity developed should be no greater than that produced when 0.05 mg of sulfate ion (SO4) is treated as the sample.
8.6 Arsenic and Antimony (as As) — To 141 mL (200 g) of sample in a 400 mL beaker add 5 mL of sulfuric acid, and evaporate to dense fumes of sulfur trioxide in a hood. Cool, cautiously add 10 mL of water, and again evaporate to dense fumes of sulfur trioxide. Cool, and cautiously wash into a generator flask with water to make a volume of 35 mL. Proceed as described in the General Method for Arsenic (and Antimony) under in SEMI C1, Section 3.4.5, starting with the sentence which begins, "Swirl the flask...." Any red color in the silver diethyldithiocarbamate solution of the sample should be no greater than that of the standard containing 0.001 mg of arsenic (As).
8.7 Trace Metal Analysis —
Gold (Au) — Analyze by graphite atomic absorption using the manufacturer's recommended procedure. This technique has been shown to give satisfactory results using a 1:4 dilution and Zeeman background correction. Each laboratory must determine the appropriate dilution and background correction for its instrument to meet the specification limit.
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). Alternate methods may be used as long as appropriate method validation as per SEMI C1 can be demonstrated. studies demonstrate recovery between 75–125% of a known sample spike for half of the value of each specified item.
8.7.1 Special Reagents
8.7.1.1 Nitric Acid, Ultra Pure — Use nitric acid specified for ultra low metal ion content.
8.7.1.2 2% Nitric Acid Solution — Dilute 20 mL of ultra pure nitric acid to 1 L using water meeting the criteria for Type E1.1 in ASTM D5127.
8.7.2 Sample Preparation
8.7.2.1 In a clean environment, place 250 g of sample in a PTFE evaporating dish. Slowly evaporate on a hot plate, avoiding loss of sample by effervescence or spattering until approximately 2 mL of liquid remains. Cool, and transfer quantitatively to a 50 mL volumetric flask using 2% nitric acid for rinsing and dilution to volume. Run a reagent blank.
8.7.3 Analysis
8.7.3.1 Using the acid sample and reagent blank, analyze group 1 elements by flame atomic absorption spectroscopy and all other elements by plasma emission spectroscopy.
9 Grade 2 Procedures
NOTE 2: Each laboratory is responsible for verifying the validity of the method within its own operation.
9.1 Non-Metal Impurities — See Section 8, which contains procedures for the following tests:
Assay
Color (APHA)
Chloride
Phosphate
Sulfate
9.2 Trace Metals Analysis
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), beryllium (Be), bismuth (Bi), boron (B), cadmium (Cd), calcium (Ca), chromium (Cr), cobalt (Co), copper (Cu), gallium (Ga), germanium (Ge), gold (Au), iron (Fe), lead (Pb), lithium (Li), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), niobium (Nb), potassium (K), silver (Ag), sodium (Na), strontium (Sr), tantalum (Ta), tin (Sn), titanium (Ti), vanadium (V), and zinc (Zn), and zirconium (Zr). Alternative methods may be used as long as appropriate method validation as per SEMI C1 can be demonstrated. studies demonstrate a recovery between 75 - 125% of a known sample spike for half of the value of each specified element.
9.2.2 Special Reagents
9.2.2.1 Nitric Acid, Ultra Pure — Use nitric acid specified for low metal ion content.
9.2.2.2 7.0% Nitric Acid Solution — Dilute 20 g of ultrapure nitric acid to 200 g using water meeting the criteria for Type E1.1 in ASTM D5127.
9.2.2.3 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.
9.2.2.4 Indium Internal Standard — Make up a indium internal standard solution to a concentration of 20 mg/mL (ppm) from a appropriate concentrated indium standard solution.
9.2.3 Sample Preparation
9.2.3.1 In a clean environment, place 2.00 g of sample into a tared FEP bottle (30 mL), dilute with Type E1.1 water to a final weight of 20.0 g. Add 20 mL of the indium internal standard solution. Run a reagent blank.
9.2.4 Analysis
9.2.4.1 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 7.0% nitric acid solution and the indium internal standard such that the final concentration is 20 ng/g of indium.
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 VLSI Grade Procedures
This section does not apply to this chemical.
14 Tier A Procedures
14.1 This section does not apply to this chemical.
15 Tier B Procedures
15.1 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 Process Liquid Chemicals Committee considers a test method to be valid only if method validation according to SEMI C1 can be demonstrated. there is a documented recovery study showing a recovery of 75–125%. Recovery is for a known sample spike at 50% of the specified level.
16 Tier C Procedures
16.1 This section does not apply to this chemical.
17 Tier D Procedures
This is a draft document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted standard. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone:408.943.6900 Fax: 408.943.7943
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