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SEMI C1-0705 © SEMI 1978, 2005 2 3 Referenced Standards and Docum ents 3.1 ASTM Standar d s 1 ASTM D5127 — Standard Guide for Ultra Pure Water Us ed in the Electronics an d Semiconductor Ind ustry ASTM E203 — Standard Te…
SEMI C1-0705 © SEMI 1978, 2005 1
SEMI C1-0705
GUIDE FOR THE ANALYSIS OF LIQUID CHEMICALS
This guide 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 1978; previously
published July 2004.
1 Purpose
1.1 Liquid Chemicals are used extensively during the production of semiconductor devices; their purity has been
shown to affect the device yield during the manufacturing processes.
1.2 Since there is a wide range of semiconductor devices being produced, different levels of purity have been
established as standards and guidelines for each liquid chemical.
1.3 This guide describes the various analytical procedures for standards verification procedures required to meet a
specific liquid chemical specification.
2 Scope
2.1 All liquid chemical standards consist of guidelines, specifications and validated analytical procedures. Suitable
analytical procedures are defined in each standard for each grade of liquid chemical such that their sensitivity meets
the requirements of each of the respective grades of liquid chemicals.
2.2 This guide provides an overview of each of the methods used for liquid chemical certification. Each grade of
liquid chemicals (1–5) that have been validated analytically using the appropriate procedures described in this guide
can be described as “meeting SEMI specifications.”
2.3 Analytical Procedures — The procedures used to establish a liquid chemical specification can be found in §7.
The Analytical Procedures are listed in Table 1.
2.4 Safety — Because of the continuing evolution of safety precautions, it is impossible for this publication to
provide definite statements related to the safe handling of individual liquid chemicals. The user is referred to
product labels, product data sheets, government regulations, and other relevant literature.
NOTICE: This guide does not purport to address safety issues, if any, associated with its use. It is the
responsibility of the users of this guide to establish appropriate safety and health practices and determine the
applicability of regulatory or other limitations prior to use.
Table 1 Analytical Procedures
7.1 Acidity and Alkalinity
7.2 Assay by Wide Bore Column Gas Chromatography
7.3 Color
7.4 Residue after Evaporation
7.5 Residue after Ignition
7.6 Trace Arsenic (and Antimony) Determination
7.7 Use of a pH Meter
7.8 Ion Chromatography
7.9 Atomic Absorption Spectrometry (AAS)
7.10 Flame Emission Spectrometry
7.11 Graphite Furnace Atomic Absorption Spectrometry (GFAAS)
7.12 Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)
7.13 Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
7.14 Calibration and Measurement Method for Particles in Liquids
SEMI C1-0705 © SEMI 1978, 2005 2
3 Referenced Standards and Documents
3.1 ASTM Standards
1
ASTM D5127 — Standard Guide for Ultra Pure Water Used in the Electronics and Semiconductor Industry
ASTM E203 — Standard Test Method for Water Using Volumetric Karl Fischer Titration
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
4 Requirements
4.1 Abbreviations and Signs — In this guide abbreviations and signs used shall be restricted to those used in
publications of the American Chemical Society (ACS)
2
.
4.2 Accuracy and Tolerances in Measurements — In a test procedure, unless otherwise specified, the accuracy
required in the amount of sample taken shall be understood to be within 2.0% of the stated amount, whether a
weight or a volume. Where a dilution is performed to a stated volume or a stated volume of a solution is taken, that
volume shall be within 2.0% of the stated amount.
4.3 Acidity and Alkalinity — A test for acidity or alkalinity, or both, of liquid chemicals may be specified. (See
Acidity and Alkalinity in ¶7.1.)
4.4 Analytical Blank — Where a “blank” is specified to be run, unless otherwise stated, it shall be performed with
the same quantities of the same reagents and in a manner identical to that followed with the sample portion under
test, but with the material itself omitted.
4.5 Apparatus — Apparatus, unless otherwise qualified, shall be that commonly employed in the conduct of the
relevant test.
4.6 Atomic and Formula Weights — Atomic weights (i.e. atomic masses) used shall be those of the latest
publication of The International Union of Pure and Applied Chemistry (IUPAC)
3
. Formula weights shall be
calculated from a given empirical (molecular) formula by addition of the stated multiples of the atomic weights.
Unless otherwise stated, formula weights shall be rounded to 2 significant figures to the right of the decimal point
(see Rounding of Numbers, ¶4.17).
4.7 Comparison of Analytical Results with Specification Limits — In the comparison of an analytical result for a test
with the numerical limit associated with the specification, the result shall be rounded to the number of significant
figures indicated for that limit. (See Rounding of Numbers, ¶4.17.) Consequently, a specification stated at 96%
minimum will be met by a result as small as 95.5%, and that stated as 96.0% minimum will be met by a result as
small as 95.95%. A specification of 0.1% maximum will be met by a result as large as 0.149%, and that of 0.10%
maximum by a result as large as 0.105%. In those specifications given with no digit following the decimal point,
such as 10 ng/mL maximum, a test result as large as 10.5 ng/mL will meet the specification. This use of a decimal
point is made to clarify the difference between converting 0.01 mg/mL to 10 ng/mL and converting 0.010 mg/mL to
10. ng/mL.
4
4.8 Density — The density of a liquid shall be determined for the compound in air at 25°C and be expressed in
grams/milliliter (g/mL). Where the specific gravity, with respect to water, is determined, it shall be expressed as
density by the use of tabular values for the density of water at the relevant temperature(s).
4.9 Desiccator — A desiccator shall imply a tightly closed container charged with a suitable desiccant (commonly
calcium chloride or sulfate) that allows an atmosphere of low humidity to be maintained.
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
2 http://www.cas.org/ONLINE/standards.html, American Chemical Society, 1155 Sixteenth Street, NW, Washington DC, 20036, Phone: 202-
872-4600, Fax: 202-872-4615, Website: http://www.chemistry.org
3 The International Union of Pure and Applied Chemistry, PO Box 13757, Research Triangle Park, NC 27709-3757, USA, Website:
http://www.iupac.org
4 H.A. Flachka, A.J. Barnard Jr., P.E. Sturrock. Quantitative Analytical Chemistry, Willard Grant Press, 2nd ed., 1980, p 4.
SEMI C1-0705 © SEMI 1978, 2005 3
4.10 Drying or Igniting to Constant Weight — A statement “dried to a constant weight” or “ignited to a constant
weight” shall imply that two separate weighings differ by no more than ± 0.4 mg (unless otherwise specified), where
the second weighing follows a second drying (for one hour (unless otherwise stated) or ignition for 15 minutes
(unless otherwise stated), respectively.
4.11 Expression of Content and Concentration — Unless otherwise stated, a specification limit and experimental
results related to it shall be expressed in units of weight by weight. The concentration of a solution of a test reagent
shall be expressed either in molarity or normality or as percent weight by volume. A redox normality value shall
always be followed, parenthetically, by the relevant molarity. In the approximate dilution of reagents, a
parenthetical expression of two numbers with an intervening “plus” sign shall imply that the relative volume of the
stated reagent given by the first number shall be admixed with the relative volume of water given by the second
number. Thus, “dilute” sulfuric acid (1 + 3) directs that one volume of reagent grade sulfuric acid be added to 3
volumes of water and the mixture stirred to form a uniform solution.
4.12 Filtration — A statement to “filter,” unless qualified, shall imply filtration through suitable filter paper until
the filtrate is clear.
4.13 Physical Properties — Physical properties shall not usually be employed for specification purposes; for
information, however, representative values for a particular liquid chemical, as supplied, may be included in the
standard for that liquid chemical. Where relevant, physical properties shall be specified for 25°C.
4.14 Reagent Chemicals — Unless otherwise stated, reagents to be used in tests shall conform to the minimum
standards of quality set forth in the current edition of Reagent Chemicals, published by the American Chemical
Society
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.
4.15 Residue after Evaporation — A “residue after evaporation” test may be used in the assessment of liquid
chemicals. (See Determination of Residue after Evaporation, ¶7.4.)
4.16 Residue after Ignition — A “residue after ignition” test serves to assess the amount of nonvolatile inorganic
matter present in a sample. (See Determination of Residue after Ignition, ¶7.5.)
4.17 Rounding of Numbers — The following rules for “rounding” of measured or calculated values shall be
employed:
4.17.1 When the figure next beyond the last place to be retained is less than 5, leave unchanged the figure in the last
place retained.
4.17.2 When the figure next beyond the last place to be retained is greater than 5, increase by 1 the figure in the last
place retained.
4.17.3 When the figure next beyond the last place to be retained is 5 and there are no figures beyond this 5 or only
zeroes, (a) increase by 1 the figure in the last place retained if it is odd, or leave the figure unchanged if it is even.
4.17.4 When the figure next beyond the last place to be retained is 5 and there are figures other than zeroes beyond
this 5 increase by 1 the figure in the last place retained.
4.17.5 Obtain the rounded value in one step by direct rounding and not in two or more steps of successive
roundings.
4.18 Samples and Sampling — For liquid chemicals provided in small containers, one (or more) should be freshly
opened for testing, thereby reducing possibilities for contamination or change in composition (for example, by
moisture pickup). Where the liquid chemical is provided in larger bulk quantities, one or more drums or other
containers shall be sampled to avoid cross contamination, and the combined sample shall be placed in a labeled,
well-cleaned container that shall be tightly closed and transferred expeditiously to the testing laboratory.
4.19 Specifications and Specification Limits — The specifications provided by this guide are intended to serve for
liquid chemicals to be used in the manufacture and processing of semiconductors and advanced electronic devices
and circuits. The specifications and the associated test procedures are based on the experience of suppliers and users
and also on published studies relating to liquid chemicals of the required quality. The function of the specifications
is to establish minimum standards of quality.
5 Available from American Chemical Society, 1155 Sixteenth Street, NW, Washington DC, 20036, Phone: 202-872-4600, Fax: 202-872-4615,
Website: http://www.chemistry.org