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ACETIC A CID SEMI C18-0301 © SEMI 1978, 20 01 1 SEMI C18-0301 SPECIFICA TION FOR AC ETIC ACID This spe cifica tion was te chnically approve d by the G lobal Process Che micals Com mittee and is the dire ct responsi bilit…
SEMI C16-0299 © SEMI 1997, 2005 2
7 Detection Limits
7.1 If a detection limit is reported, the specific method or published variant by which the detection limit was
obtained, should be named. The level of the lowest standard used in determination of a detection limit should be
reported.
8 Internal Standards
8.1 For procedures calling for concentration of an analyte by cryogenic trapping, acid extraction, distillation,
hydrolization, etc., a recovery study as per Method Validation (§3.14 of SEMI C1) is required. For a method to be
viable, a recovery in the range of 75–125% is recommended.
9 Calibration Models
9.1 The span of the calibration data should include the relevant specification.
9.2 The form of the calibration model (line through origin, line, etc.) should be stated. The assumption of linearity,
underlying reliance on two point (zero and span) calibrations for analytical instruments, should be justified by
reporting the basis for such an assumption.
9.3 A list of which standards were used to develop the calibration model should be provided.
9.4 Information on which fitting technique was used (i.e., regression using ordinary least squares, weighted least
squares, partial least squares) should be provided.
9.5 Identify which, if any, transformations were applied to the calibration data prior to the fitting of the calibration
model.
9.6 Identify which response was modeled to establish calibration (i.e., peak area, peak height, response factor).
9.7 A list of the types of standards employed (i.e., internal standards, external standards, method of standard
addition) should be provided.
9.8 Report how the calibration data is incorporated in producing the results of an analysis (i.e., zero and span
correction, graph).
10 Method Precision
10.1 An estimate of method precision should be provided at the level of the specification. Any known interferants
or factors which may affect method precision should be stated.
11 Summary
11.1 Since only a minimal set of guidelines is provided, those using this guide are encouraged to provide more
detail or use more stringent guidelines than those suggested.
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 or equipment mentioned herein. These standards are subject to change without
notice.
By publication of this standard, Semiconductor Equipment and Materials International (SEMI) takes no position
respecting the validity of any patent rights or copyrights asserted in connection with any items 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 of
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consent of SEMI.
ACETIC ACID SEMI C18-0301 © SEMI 1978, 20011
SEMI C18-0301
SPECIFICATION FOR ACETIC ACID
This specification was technically approved by the Global Process Chemicals Committee and is 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 C1.1 in its entirety. Originally published
in 1978; previously published June 1999.
1 Purpose
1.1 The purpose of this document is to standardize
requirements for acetic 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 acetic 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 acetic
acid used in the semiconductor industry.
2.2 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
4.1 SEMI Standards
SEMI C1 — Specifications for Reagents
4.2 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)
Density at 25°C
1.05 g/mL
NOTE 2: This material freezes at about 16°C.
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
7 Requirements
7.1 The requirements for acetic acid for Grade 1 are
listed in Table 1.
8 Grade 1 Procedures
NOTE 3: Each laboratory is responsible for verifying the
validity of the method within its own operation.
8.1 Assay — Place 15 mL (15.8 g) of sample in a 20 ×
150 mm test tube in which is centered an accurate
thermometer. The sample tube is centered by one or
more stoppers in an outer tube about 38 × 20 mm. Cool
the entire apparatus, without stirring, in a bath of
shaved or crushed ice and sufficient water to immerse
the outer tube above the level of the acetic acid. When
the thermometer temperature is about 13°C stir to
induce freezing and read the thermometer every half
minute. The temperature that remains constant for 1 to
2 minutes is the freezing point and should not be below
16°C, indicating not less than 99.7% as CH
3
COOH.
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 Residue after Evaporation — Evaporate 95 mL
(100 g) of sample in a tared porcelain or silica dish to
dryness on a steam bath in a hood. Dry at 105°C for 30
minutes, cool in a desiccator, and weigh (see SEMI C1,
Section 3.3, Determination of Residue After
Evaporation).
8.4 Solubility in Water — Mix 10 mL of sample with
30 mL of water. Allow to stand 1 hour. The solution
should be as clear as an equal volume of water.
8.5 Chloride — Dilute 9.5 mL (10 g) of sample with
10 mL of water. Add 1 mL of silver nitrate reagent
solution 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.
SEMI C18-0301 © SEMI 1978, 2001 ACETIC ACID2
8.6 Phosphate — Evaporate 9.5 mL (10 g) of sample
to dryness on a steam bath in a hood. Dissolve the
residue, warming if necessary, 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 should be no
greater than that produced when 0.01 mg of phosphate
ion (PO
4
) is treated as the sample.
8.7 Substances Reducing Dichromate — To 10 mL
(10.5 g) of sample, add 1.0 mL of 0.1 N (0.017 M)
potassium dichromate solution and cautiously add 10
mL of sulfuric acid. Cool the solution to room
temperature and allow to stand for 30 minutes. Add 50
mL of water slowly and cautiously with continual
swirling, allow to cool, and then add 1 mL of freshly
prepared potassium iodide reagent solution. Titrate the
liberated iodine with 0.1 N (0.1 M) thiosulfate solution
using starch as the indicator. Compare the volume of
thiosulfate solution required with that for a 10 mL
water blank prepared in parallel with the sample. The
difference between the titrations for sample and blank
should be no greater than 0.40 mL.
8.8 Substances Reducing Permanganate — Dilute 40
mL (42 g) of sample with 10 mL of water. Cool to
15°C, add 0.30 mL of 0.1 N (0.02 M) potassium
permanganate, and allow to stand at 15°C for 10
minutes. The pink color should not be entirely
discharged.
8.9 Sulfate — To 95 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 (SO
4
) is treated
as the sample.
8.10 Arsenic and Antimony (as As) — To 190 mL (200
g) of sample in a 400 mL beaker, add 5 mL of nitric
acid and 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 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).
8.11 Acetic Anhydride — Place 52.2 g (50 mL) of
sample in a 250 mL titration flask. In a second flask
place 50 mL of glacial acetic acid known to be free
from acetic anhydride (see NOTE 3). Into each flask
pipet 10 mL of 1.0% solution of 4, 4' -
methylenedianiline (4, 4' -diaminodiphenylmethane) in
glacial acetic acid (see NOTE 4) and add 0.10 mL of
1.0% solution of crystal violet in glacial acetic acid.
Titrate each solution with a 0.1 N solution of perchloric
acid in glacial acetic acid (see NOTE 5) to a green
endpoint. Subtract the volume for the titration of the
sample from the volume for the other titration. One mL
of 0.1 N perchloric acid corresponds to 0.0194%
(CH
3
CO)
2
O for a 50 mL sample.
NOTE 4: Glacial acetic acid suspected of containing
anhydride may be purified by adding 0.50 mL of water per
100 mL and digesting overnight in a glass-stoppered flask on
the steam bath. If this acid is used for comparison in the
above test, 0.25 mL of water should be added to the flask
containing the test sample just before the endpoint, because
water affects the indicator change slightly.
NOTE 5: Dissolve 2.50 g of 4, 4' -methylenedianiline
(colorless or only slightly colored) in glacial acetic acid to
make 250 mL. Protect the solution from light.
NOTE 6: Slowly add 4.5 mL of 70% perchloric acid to about
400 mL of glacial acetic acid and dilute with glacial acetic
acid to 500 mL. Standardize against potassium hydrogen
phthalate in glacial acetic acid solution using crystal violet as
indicator.
8.12 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), gold (Au),
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 studies demonstrate
recovery between 75 - 125% of a known sample spike
for half of the value of each specified item.
8.12.1 Special Reagents
8.12.1.1 Solution A — Glycerol (ACS Reagent Grade)
10 g, Adipic Acid (99+%) 1 g, EDTA Acid (ACS
Reagent Grade) 0.1 g. Dilute to 1 L using water
meeting the criteria for Type E1 in ASTM D5127.
8.12.1.2 Nitric Acid, Ultra Pure — Use nitric acid
specified for ultra low metal ion content.
8.12.1.3 2% Nitric Acid Solution — Dilute 10 mL of
ultra pure nitric acid to 1 L using water meeting the
criteria for Type E1 in ASTM D5127.
8.12.2 Sample Preparation
8.12.2.1 In a clean environment, place 100 grams of
sample in a PTFE dish. Add 50 mL of solution A.
Slowly evaporate on a hot water bath avoiding loss of