ASTM F1238-95(2003)

Standard Specification for Refractory Silicide Sputtering Targets for Microelectronic Applications

ABSTRACT
This specification covers refractory silicide sputtering targets for use in microelectronic applications. Targets shall be classified by the following major constituents: molybdenum silicide, tantalum silicide, titanium silicide, and tungsten silicide. Target composition shall be stated as the atomic ratio of silicon to metal and shall conform to the prescribed maximum impurity level for: alkalis (potassium, lithium, sodium), refractory metals (molybdenum, tantalum, titanium, and tungsten), iron, other metals (aluminum, boron, calcium, cobalt, chromium, copper, magnesium, manganese, and nickel), carbon, and oxygen. Low alpha grade targets shall contain the prescribed maximum impurity level of uranium and thorium Dimensional and physical properties such as relative, actual, and theoretical densities are specified. The actual target density shall be determined by Archimedes principle or other acceptable techniques and the theoretical density shall be calculated from the given formula. The following chemical analytical methods shall be used: atomic absorption, combustion or infrared spectrometry, inert gas fusion, and alpha-emission rate analysis, depending on the impurity to be analyzed. There shall be no radial cracks, other cracks, or chips on the sputtering surface.
SCOPE
1.1 This specification covers sputtering targets fabricated from metallic silicides (molybdenum silicide, tantalum silicide, titanium silicide, and tungsten silicide). These targets are referred to as refractory silicide targets, and are intended for use in microelectronic applications.
1.2 The values stated in SI units are regarded as standard.

General Information

• Status: Historical
• Publication Date: 09-Dec-1999
• ICS: 31.100 - Electronic tubes
• Technical Committee: F01 - Electronics
• Drafting Committee: F01.17 - Sputter Metallization

Relations

• Replaces: ASTM F1238-95(1999) - Standard Specification for Refractory Silicide Sputtering Targets for Microelectronic Applications
• Effective Date: 10-Dec-1999
• Replaced By: ASTM F1238-95(2011) - Standard Specification for Refractory Silicide Sputtering Targets for Microelectronic Applications (Withdrawn 2020)
• Effective Date: 01-Jun-2011

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F1238 – 95 (Reapproved 2003)
Standard Specification for
Refractory Silicide Sputtering Targets for Microelectronic
1
Applications
This standard is issued under the fixed designation F1238; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
NOTE 1—Silicon content may be calculated from the following for-
1. Scope
mula:
1.1 This specification covers sputtering targets fabricated
Ratio 3 A
frommetallicsilicides(molybdenumsilicide,tantalumsilicide,
Silicon, % 5 3 100
~Ratio 3 A! 1 B
titanium silicide, and tungsten silicide). These targets are
referred to as refractory silicide targets, and are intended for
where:
use in microelectronic applications.
A = atomic weight of silicon, and
2, 3, 4
B = atomic weight of metal, (see Table 1 ).
1.2 The values stated in SI units are regarded as standard.
2. Terminology
4.3 Impurities—Maximum impurity levels shall conform to
2.1 Definitions of Terms Specific to This Standard:
the requirements prescribed in Table 2.
2.1.1 raw material lot—powder mix lot from which a
4.4 Low Alpha Grade—When low alpha grade targets are
number of targets is fabricated.
ordered they shall contain a maximum impurity level of
2.1.2 relative density—actual target density related to theo-
uranium and thorium as agreed upon by the supplier and the
retical density, (see 3.1.3), stated as percent.
purchaser.The method of analysis for these elements shall also
2.1.3 theoretical density—calculated density for given com-
be agreed upon.
position as described in 5.3.
NOTE 2—An alternative method for defining low alpha grade targets is
to specify an alpha-emission rate. Specific methodology and emission rate
3. Ordering Information
shall be agreed upon by supplier and purchaser.
3.1 Orders for these targets shall include the following:
4.5 When required by purchaser, supplier will provide a 25
3.1.1 Type and ratio (see 4.1 and 4.2),
g sample of material that is representative of the total produc-
3.1.2 Whether low alpha grade is required, (see 4.4),
tion process for the particular raw material lot, (see Section 8).
3.1.3 Minimum relative density, if other than 90 %, (see
5.1),
5. Physical Properties
3.1.4 Configuration, (see 6.1),
5.1 Minimum relative density shall be 90 %. Other relative
3.1.5 Whether certification is required, (see 10.1).
densities may be specified by the purchaser.
4. Chemical Composition 5.2 ActualtargetdensityshallbedeterminedbyArchimedes
principle or other acceptable techniques.
4.1 Type—Targets shall be classified by the following major
5.3 Theoretical density shall be calculated from the follow-
constituents:
ing formula:
4.1.1 Molybdenum silicide, (Mo/Si),
4.1.2 Tantalum silicide, (Ta/Si),
C 1 ~Ratio 2 2! 3 A
Theoretical density 5
4.1.3 Titanium silicide, (Ti/Si), and C/D 1 Ratio 2 2 3 A/E
~ !
4.1.4 Tungsten silicide, (W/Si).
4.2 Ratio—Target composition shall be stated as the atomic
ratio of silicon to metal, such asTa/Si 2.5. Ratio tolerance shall
2
Molybdenum disilicide and WSi (equilibrim tetragonal phase) densities were
2
be 60.1.Therefore,theacceptablerangefora2.5targetwould
computed from crystal lattice parameters tabulated in “Crystal Data-Determinative
be 2.4 to 2.6.
Tables, Third Edition,” Vol 2, U. S. Department of Commerce, National Bureau of
Standards and the Joint Committee on Powder Diffraction Standards, 1973, and
JCPDS Data File Number 11-195. Tantalum disilicide (hexagonal) and
1
This specification is under the jurisdiction of ASTM Committee F01 on a-TiSi (orthorhombic) data are from Einspruch, N. G. and Larrabee, G. B., VLSI
2
Electronics and is the direct responsibility of Subcommittee F01.17 on Sputter Electronics Microstructure Science, Vol 6, Table A.1, Academic Press, NY, NY,
Metallization. 1983.
3
Current edition approved Sept. 15, 1995. Published November 1995. Originally Binary Alloy Phase Diagrams, Vol 2, ASM, Metals Park, OH.
´1 4
publishedasF1238 – 89.LastpreviouseditionF1238 – 89 (1994) .DOI:10.1520/ Einspruch, N. G., and Larrabee, G. B., VLSI Electronics Microstructure
F1238-95R03. Science, Vol 6, Table A.1, Academic Press, NY, NY, 1983.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

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F1238 – 95 (2003)
A
TABLE 1 Weights and Densities of Constituents
8. Sampling
Atomic or Molecular
3
8.1 Analyses for ratio, (see 4.2) and for impurities, (see 4.3
Constituents Density (g/cm )
Weight
and 4.4) shall be performed on a sample that is representative
Molybdenum (Mo) 95.94 .
of the finished product.
Silicon (Si) 28.09 2.33
...