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SEMI C36-0705 © SEMI 1981, 2005 1 SEMI C36-0705 SPEC IFICAT IONS FOR PHOSPHORIC ACID This specification was technically approved by the gl obal Liquid Chem icals Committee. This edition w as approved for publication by t…

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SEMI C35-0301 © SEMI 1979, 2001 NITRIC ACID4
Previous SEMI Reference # C1.12-96 C7.6-95 C8.6-95
Grade 1 Grade 2 Tier B
(Specification) (Specification) (Guideline)
Gold (Au) 0.3 ppm max 5 ppb max 1 ppb max
Iron (Fe) 0.2 ppm max 5 ppb max 1 ppb max
Lead (Pb) 0.1 ppm max 10 ppb max 1 ppb max
Lithium (Li) -- 5 ppb max 1 ppb max
Magnesium (Mg) 0.3 ppm max 10 ppb max 1 ppb max
Manganese (Mn) 0.2 ppm max 10 ppb max 1 ppb max
Molybdenum (Mo) -- 10 ppb max 1 ppb max
Nickel (Ni) 0.05 ppm max 10 ppb max 1 ppb max
Niobium (Nb) -- 10 ppb max 1 ppb max
Potassium (K) 0.3 ppm max 5 ppb max 1 ppb max
Silicon (Si) -- -- 1 ppb max
Silver (Ag) -- 10 ppb max 1 ppb max
Sodium (Na) 0.3 ppm max 5 ppb max 1 ppb max
Strontium (Sr) -- 10 ppb max 1 ppb max
Tantalum (Ta) -- 10 ppb max 1 ppb max
Thallium (Tl) -- 10 ppb max 1 ppb max
Tin (Sn) 0.3 ppm max 10 ppb max 1 ppb max
Titanium (Ti) 0.3 ppm max 10 ppb max 1 ppb max
Vanadium (V) -- 10 ppb max 1 ppb max
Zinc (Zn) 0.3 ppm max 10 ppb max 1 ppb max
Zirconium (Zr) -- 10 ppb max 1 ppb max
Particles in bottles:
size, #/mL
≥ 1.0 µm, 25 max ≥ 0.5 µm, 25 max ≥ 0.5 µm, 5 max
≥ 0.2 µm, TBD
NOTE 1: This material may darken during storage due to a photochemical reaction.
NOTICE: SEMI makes no warranties or representations as to the suitability of the standards set forth herein for any
particular application. The determination of the suitability of the standard 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 mentioned herein. These standards are subject to change without notice.
The user’s attention is called to the possibility that compliance with this standard may require use of copyrighted
material or of an invention covered by patent rights. 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.
Copyright by SEMI® (Semiconductor Equipment and Materials
International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o
f
the contents in whole or in part is forbidden without express written
consent of SEMI.
SEMI C36-0705 © SEMI 1981, 2005 1
SEMI C36-0705
SPECIFICATIONS FOR PHOSPHORIC ACID
This specification was technically approved by the global Liquid Chemicals Committee. This edition was
approved for publication by the global Audits and Reviews Subcommittee on April 7, 2005. It was available
at www.semi.org in June 2005 and on CD-ROM in July 2005. Originally published in 1981; previously
published March 2001.
1 Purpose
1.1 The purpose of this document is to standardize requirements for phosphoric acid used in the semiconductor
industry and testing procedures to support those standards. Test methods have been shown to give statistically valid
results.
2 Scope
2.1 The scope of this document is all grades of phosphoric acid used in the semiconductor industry.
2.2 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 limitations prior to use.
3 Limitations
3.1 None.
4 Referenced Standards and Documents
4.1 ASTM Standards
1
ASTM D5127 — Standard Guide for Ultra Pure Water Used in the Electronics and Semiconductor Industry
NOTE 1: As listed or revised, all documents cited shall be the latest publications of adopted standards.
5 Terminology
5.1 None.
6 Physical Property (for information only)
80% 1.64 g/mL
Density at 25C
86% 1.70 g/mL
7 Requirements
7.1 The requirements for phosphoric acid for Grades 1, 2, and 3 are listed in Table 1.
8 Grade 1 Procedures
8.1 Assay — Weigh to the nearest 1 mg about 1 mL of sample in a 250 mL glass-stoppered flask, dilute with 120
mL of water, add 0.5 mL of thymolphthalein indicator solution, and titrate with standardized 1 N sodium hydroxide
to the first appearance of a blue color against a white background.
% Assay =
mL
N
of NaOH
4.900
Weight of sample (g)
8.2 Chloride — Dilute 9 mL (15 g) of sample with 25 mL of water, and add 0.5 mL of nitric acid and 1 mL of silver
nitrate reagent solution. Any turbidity produced should be no greater than that produced when 0.015 mg of chloride
ion (Cl) is treated as the sample.
1 American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania 19428-2959, USA. Telephone:
610.832.9585, Fax: 610.832.9555, Website: www.astm.org
SEMI C36-0705 © SEMI 1981, 2005 2
8.3 Nitrate — Prepare the following solutions:
Sample Solution A: Add 3 mL (5 g) of sample to 2 mL of water,
dilute to 50 mL with brucine sulfate reagent
solution and mix.
Control Solution B: Add 3 mL (5 g) of sample to 0.025 mg of nitrate
ion (NO
3
). Dilute to 50 mL with brucine sulfate
reagent solution, and mix.
Blank Solution C: Use 50 mL of the brucine sulfate reagent
solution.
8.3.1 Heat the three solutions in a preheated (boiling water) bath for 10 minutes. Cool rapidly in an ice bath to
room temperature. Set a spectrophotometer 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 not exceed that of Control Solution B.
8.4 Sulfate
8.4.1 The following inductively coupled plasma (ICP) method has given satisfactory results for the determination of
sulfate (SO
4
) by the analysis of sulfur (S) and subsequent calculation to determine the stoichiometric equivalent of
sulfate.
NOTE 2: While this method has been shown to accurately determine sulfate concentration in phosphoric acid, the ICP
methodology actually evaluates sulfur. Therefore, other sulfur species (organic, etc.) will also be determined by this method, and
the “calculated” sulfate value may be higher than the actual sulfate concentration in a given sample.
8.4.2 Special Reagents
8.4.2.1 Water — The water used for all dilution, calibration and standards should meet at a minimum, the criteria
for Type E1.1 in ASTM D5127.
8.4.2.2 Scandium Internal Standard — A scandium standard solution is utilized such that final diluted samples will
have a scandium concentration of 40 ppm.
8.4.3 Sample Preparation
8.4.3.1 Dilute 20 g of phosphoric acid to 100 mL with water. (An aliquot of the concentrated scandium standard
solution should also be added during the dilution process such that the final diluted sample will have a scandium
concentration of 40 ppm.)
8.4.4 Analysis
8.4.4.1 Using the prepared sample, analyze the sulfur content using inductively coupled plasma (ICP) spectroscopy
that has been standardized using appropriate sulfur standard solutions. A wavelength of 180.731 nm has been
shown to give satisfactory results.
8.4.5 Calculation
8.4.5.1 The associated sulfate (SO
4
) concentration is determined using the stoichiometric conversion (SO
4
= 3 S).
8.5 Trace Metal Analysis
8.5.1 The following method has given satisfactory results in determining trace metal impurities at the value
specified for each of the following trace metals: arsenic (As), gold (Au), cobalt (Co), chromium (Cr), nickel (Ni),
lead (Pb), and antimony (Sb). Alternate methods may be used as long as they are validated for each trace metal
according to SEMI C1, ‘Method Validation’.
8.5.2 Special Reagents
8.5.2.1 Nitric Acid, Ultra Pure — Use nitric specified for ultra low metal ion content.
8.5.2.2 Sample Preparation — In a clean environment, weigh 1.00 g (5.00 g for arsenic) of sample into each of two
30 mL polypropylene cups. Add 0.2 mL ultra pure nitric acid to each cup. Make standard addition to one cup.