1、Designation: F1238 95 (Reapproved 2011)Standard Specification forRefractory Silicide Sputtering Targets for MicroelectronicApplications1This standard is issued under the fixed designation F1238; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers sputtering targets fabricatedfrom metallic silicides (molybdenum sil
3、icide, tantalum silicide,titanium silicide, and tungsten silicide). These targets arereferred to as refractory silicide targets, and are intended foruse in microelectronic applications.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in this
4、standard.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 raw material lotpowder mix lot from which anumber of targets is fabricated.2.1.2 relative densityactual target density related to theo-retical density, (see 3.1.3), stated as percent.2.1.3 theoretical densitycalculated d
5、ensity for given com-position as described in 5.3.3. Ordering Information3.1 Orders for these targets shall include the following:3.1.1 Type and ratio (see 4.1 and 4.2),3.1.2 Whether low alpha grade is required, (see 4.4),3.1.3 Minimum relative density, if other than 90 %, (see5.1),3.1.4 Configurati
6、on, (see 6.1),3.1.5 Whether certification is required, (see 10.1).4. Chemical Composition4.1 TypeTargets shall be classified by the following majorconstituents:4.1.1 Molybdenum silicide, (Mo/Si),4.1.2 Tantalum silicide, (Ta/Si),4.1.3 Titanium silicide, (Ti/Si), and4.1.4 Tungsten silicide, (W/Si).4.2
7、 RatioTarget composition shall be stated as the atomicratio of silicon to metal, such as Ta/Si 2.5. Ratio tolerance shallbe 6 0.1. Therefore, the acceptable range for a 2.5 target wouldbe 2.4 to 2.6.NOTE 1Silicon content may be calculated from the following for-mula:Silicon, % 5Ratio 3 ARatio 3 A! 1
8、 B3 100where:A = atomic weight of silicon, andB = atomic weight of metal, (see Table 12, 3, 4).4.3 ImpuritiesMaximum impurity levels shall conform tothe requirements prescribed in Table 2.4.4 Low Alpha GradeWhen low alpha grade targets areordered they shall contain a maximum impurity level ofuranium
9、 and thorium as agreed upon by the supplier and thepurchaser. The method of analysis for these elements shall alsobe agreed upon.NOTE 2An alternative method for defining low alpha grade targets isto specify an alpha-emission rate. Specific methodology and emission rateshall be agreed upon by supplie
10、r and purchaser.4.5 When required by purchaser, supplier will provide a 25g sample of material that is representative of the total produc-tion process for the particular raw material lot, (see Section 8).5. Physical Properties5.1 Minimum relative density shall be 90 %. Other relativedensities may be
11、 specified by the purchaser.1This specification is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.17 on SputterMetallization.Current edition approved June 1, 2011. Published June 2011. Originallypublished as F1238 89. Last previous edi
12、tion approved in 2003 as F1238 95(2003). DOI: 10.1520/F1238-95R11.2Molybdenum disilicide and WSi2(equilibrim tetragonal phase) densities werecomputed from crystal lattice parameters tabulated in “Crystal Data-DeterminativeTables, Third Edition,” Vol 2, U. S. Department of Commerce, National Bureau o
13、fStandards and the Joint Committee on Powder Diffraction Standards, 1973, andJCPDS Data File Number 11-195. Tantalum disilicide (hexagonal) anda-TiSi2(orthorhombic) data are from Einspruch, N. G. and Larrabee, G. B., VLSIElectronics Microstructure Science , Vol 6, Table A.1, Academic Press, NY, NY,1
14、983.3Binary Alloy Phase Diagrams, Vol 2, ASM, Metals Park, OH.4Einspruch, N. G., and Larrabee, G. B., VLSI Electronics MicrostructureScience, Vol 6, Table A.1, Academic Press, NY, NY, 1983.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Sta
15、tes.5.2 Actual target density shall be determined byArchimedesprinciple or other acceptable techniques.5.3 Theoretical density shall be calculated from the follow-ing formula:Theoretical density 5C 1 Ratio 2 2! 3 AC/D 1 Ratio 2 2! 3 A/Ewhere:A = atomic weight of silicon,C = molecular weight of metal
16、 silicide, (MoSi2, etc),D = density of metal silicide, andE = density of silicon, (see Table 1).6. Dimensions6.1 Each target shall conform to an appropriate engineeringdrawing.7. Workmanship, Finish, and Appearance7.1 There shall be no radial cracks.7.2 There shall be no other cracks or chips on the
17、 sputteringsurface.7.3 Examination for cracks and chips shall be made by theunaided eye under good lighting conditions.8. Sampling8.1 Analyses for ratio, (see 4.2) and for impurities, (see 4.3and 4.4) shall be performed on a sample that is representativeof the finished product.9. Analytical Methods9
18、.1 Do analysis for ratio, (see 4.2) by a technique that has aprecision of 60.5 % silicon or better.9.2 Do analysis for impurities listed in Table 1 as follows:9.2.1 AlkalisAtomic absorption (AA) with a minimumdetection limit (mdl) of 0.2 ppm.9.2.2 CarbonCombustion/infrared spectrometry, mdl of10 ppm
19、.9.2.3 OxygenInert gas fusion, mdl of 10 ppm.9.2.4 All OthersAA or inductively coupled plasma (ICP),mdl of 5 ppm.9.2.5 Other analytical techniques may be used providedthey can be proved equivalent to the methods specified, andhave minimum detection limits of the specified methods.9.3 Analysis for ur
20、anium and thorium or alpha-emissionrate in low alpha grade targets, (see 4.4) shall have an mdl of20 % or less of the specified level.10. Certification10.1 When required by the purchaser, a certificate of analy-sis that represents the total production process for the particularraw material lot shall
21、 be provided for each target.10.2 Certificate of analysis shall state the raw material lotnumber, ratio, impurity levels, density, and dates of targetmanufacture and packaging.11. Product Marking11.1 Each target shall be marked on a non-sputtering surfacewith a unique raw material lot number and a u
22、nique targetnumber.12. Packaging12.1 Each target shall be vacuum or inert gas packed, andenclosed in a shipping carton that ensures target integrityduring shipment.13. Keywords13.1 density; microelectronics; molybdenum disilicide; re-fractory silicides; sputtering; sputtering targets; tantalum disi-
23、licide; titanium disilicide; tungsten disilicideTABLE 1 Weights and Densities of ConstituentsAConstituentsAtomic or MolecularWeightDensity (g/cm3)Molybdenum (Mo) 95.94 .Silicon (Si) 28.09 2.33Tantalum (Ta) 180.95 .Titanium (Ti) 47.88 .Tungsten (W) 183.85 .Silicides:MoSi2152.12 6.24TaSi2237.13 9.07Ti
24、Si2104.06 4.13BWSi2240.02 9.87CAMolecular weights of silicides were derived from elemental atomic weights.Density of silicides were calculated from x-ray data.2BPertains to a-TiSi2, stable at temperatures less than 1200C3.CPertains to the tetragonal phase, which is typical for bulk material (for exa
25、mple.sputtering targets) made from WSi2powder densified in elevated temperaturemanufacturing processes. Sputtered thin film may stabilize in the higher densityhexagonal phase.4TABLE 2 Maximum Impurity Levels, ppmAlkalis, each (K, Li, Na) 25Refractory metals, total (Mo, Ta, Ti, W), when present as im
26、purities 150Iron, total 100Other metals, total (Al, B, Ca, Co, Cr, Cu, Mg, Mn, Ni) 250Carbon 500Oxygen 2000F1238 95 (2011)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expr
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