Source: http://www.google.com/patents/US5424252?dq=inventor:%22Arthur+R.+Hair%22
Timestamp: 2014-12-26 02:52:18
Document Index: 394149197

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Patent US5424252 - Photo-plating solution and process - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsAn electroless metal or alloy plating solution as a photo-plating solution contains at least one of copper, nickel, cobalt or tin, and a sacrificial reagent which supplies electrons as a result of irreversible oxidative decomposition. A semiconductor is supported on a substrate, and dipped in the photo-plating...http://www.google.com/patents/US5424252?utm_source=gb-gplus-sharePatent US5424252 - Photo-plating solution and processAdvanced Patent SearchPublication numberUS5424252 APublication typeGrantApplication numberUS 08/152,925Publication dateJun 13, 1995Filing dateNov 16, 1993Priority dateOct 4, 1991Fee statusLapsedPublication number08152925, 152925, US 5424252 A, US 5424252A, US-A-5424252, US5424252 A, US5424252AInventorsShinya MorishitaOriginal AssigneeKabushiki Kaisha Toyota Chuo KenkyushoExport CitationBiBTeX, EndNote, RefManPatent Citations (10), Non-Patent Citations (4), Referenced by (10), Classifications (16), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetPhoto-plating solution and processUS 5424252 AAbstract An electroless metal or alloy plating solution as a photo-plating solution contains at least one of copper, nickel, cobalt or tin, and a sacrificial reagent which supplies electrons as a result of irreversible oxidative decomposition. A semiconductor is supported on a substrate, and dipped in the photo-plating solution, and the surface of the semiconductor is irradiated with light having a higher level of energy than the exciting energy of the semiconductor. A thick coating containing at least one of copper, nickel, cobalt or tin can be formed on that portion of the semiconductor which has been irradiated with light.
What is claimed is: 1. A process for photo-plating a semiconductor which comprises the steps ofsupporting a semiconductor on a substrate, immersing said semiconductor in an electroless metal or alloy plating solution which comprises at least one metal or at least one alloy thereof, said at least one metal being selected from the group consisting of copper, nickel, cobalt and tin, and a sacrificial reagent for supplying electrons by irreversible oxidative decomposition, wherein said sacrificial reagent comprises a substance serving also as a complexing agent to stabilize ions of said at least one metal in said electroless plating solution and which comprises at least one compound selected from the group consisting of amines, imines, alkanolamines, hydroxycarboxylic acids and aminocarboxylic acids, and irradiating the surface of said semiconductor with light having a higher level of energy than the exciting energy of said semiconductor; wherein said process forms a film of 10μ to several tens of μm. 2. A process as set forth in claim 1, wherein said sacrificial reagent comprises at least one compound selected from the group consisting of triethanolamine, ethylenediaminetetraacetic acid, citric acid and potassium sodium tartrate.
SUMMARY OF THE INVENTION It is an object of this invention to provide a photo-plating solution which enables the formation of a thick metal or alloy coating containing at least one of copper, nickel, cobalt or tin on only those portions of a substrate on which a semiconductor is supported.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a graph showing the reduction of dissolved oxygen concentration in relation to light irradiation time.
DETAILED DESCRIPTION OF THE INVENTION The electroless plating solution which is employed to make the photo-plating solution of this invention may be any composition if it enables the growth of a metal deposit on a nucleus of copper, nickel, cobalt or tin formed on a semiconductor by the irradiation of light, and thereby the formation of a thick metal or alloy coating. The solution may contain one or more of copper, nickel, cobalt or tin. It may further contain tungsten, molybdenum, manganese, zinc, rhenium, etc.
The photo-plating solution of this invention further contains a sacrificial reagent. The sacrificial reagent may be any substance that can supply electrons by irreversible oxidative decomposition to holes produced in the valence band of a semiconductor by the action of light. The solution preferably contains the sacrificial reagent at a concentration which is higher by at least one figure than the concentration of dissolved oxygen in the solution which may be in the range of 2 to 3�10-4 mol/l, as it also serves to remove by reduction dissolved oxygen which hinders the deposition of metal.
Even if the sacrificial reagent serving also as a complexing agent, may somewhat be consumed for reducing dissolved oxygen, the solution hardly undergoes any change in composition, since it contains the complexing agent at a concentration of 0.2 to 0.3 mol/l which is about 1,000 times higher than the dissolved oxygen concentration of 2 to 3�10-4 mol/l.
EXAMPLES The invention will now be described more specifically with reference to several examples thereof.
Example 1 Twelve substrates of alumina having a purity of 96% (Nos. 1 to 12) were degreased by three minutes of ultrasonic cleansing in acetone as a guaranteed reagent, and thereafter by 60 minutes of ultrasonic cleansing in a solution of NaOH having a concentration of 1 mol/l. The substrate surfaces were etched by 60 minutes of immersion in a solution of HF having a concentration of 1 mol/l, rinsed with water, and dried. Substrates Nos. 1 to 6 were dipped for two seconds in a sol of TiO2 (a mixture of rutile and anatase produced by Nissan Chemical Industrial Co., Ltd., and having a particle diameter of 100 to 200 Å) having a concentration of 1 g/l, were rinsed in a stream of water for 10 seconds, and were dried. Then, they were fired at 500� C. for an hour to yield alumina substrates carrying TiO2 as a semiconductor. Substrates Nos. 7 to 12 were coated by five seconds of spraying with an aqueous solution of Zn(CH3 COO)2 having a concentration of 0.05 mol/l, and were fired at 400� C. for an hour to yield alumina substrates carrying ZnO as a semiconductor.
TABLE 1______________________________________                Composition of                electroless copper                plating solution                EDTA  TEA    Tart                type  type   type______________________________________Concentration of sacrificial reagent (mol/l)EDTA                   0.3     --     --TEA                    --      0.2    --Tart                   --      --     0.3Concentration of copper salt (mol/l)CuSO4             0.04    --     0.03CuCl2             --      0.08   --HCHO concentration (mol/l)                  0.1     0.08   0.3pH                     12.5    12.8   12.8______________________________________
TABLE 2__________________________________________________________________________    Electroless copper          Structure of copper deposit   Semi- plating solution                                Portion notNo.   conductor    type       Plating conditions                                Portion irradiated with                                                    irradiated__________________________________________________________________________1  TiO2    EDTA       5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;2  TiO2    EDTA       After 5 min. of light irradiation                                Film having a thickness of about 60                                &#956;m               No deposit               left for 60 hours.3  TiO2    TEA        5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;4  TiO2    TEA        After 5 min. of light irradiation,                                Film having a thickness of about 40                                &#956;m               No deposit               left for 60 hours.5  TiO2    Tart       5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;6  TiO2    Tart       After 5 min. of light irradiation,                                Film having a thickness of about 20                                &#956; m              No deposit               left for 60 hours.7  ZnO   EDTA       5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;8  ZnO   EDTA       After 5 min. of light irradiation,                                Film having a thickness of about 30                                &#956;m               No deposit               left for 60 hours.9  ZnO   TEA        5 min. of light irradiation                                Island like semispherical particles                                with &#966;          No deposit                                of several hundreds &#8491;10 ZnO   TEA        After 5 min. of light irradiation,                                Film having a thickness of about 30                                &#956;m               No deposit               left for 60 hours.11 ZnO   Tart       5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;12 ZnO   Tart       After 5 min. of light irradiation,                                Film having a thickness of about 20                                &#956;m               No deposit               left for 60 hours.__________________________________________________________________________
Example 2 Twelve glass-epoxy substrates (Nos. 13 to 24) were degreased, and chemically etched in a mixture of sulfuric and chromic acids. Substrates Nos. 13 to 18 were dipped for two seconds in a sol of TiO2 (a mixture of rutile and anatase produced by Nissan Chemical Industrial Co., Ltd., and having a diameter of 100 to 200 Å) having a concentration of 1 g/l, rinsed in a stream of water for 10 seconds, and dried to yield glass-epoxy substrates carrying TiO2 as a semiconductor. On the other hand, a film of ZnO having a thickness of about 2,000 Å was formed by sputtering on each of substrates Nos. 19 to 24.
TABLE 3__________________________________________________________________________    Electroless copper          Structure of copper deposit   Semi- plating solution                                Portion notNo.   conductor    type       Plating conditions                                Portion irradiated with                                                    irradiated__________________________________________________________________________13 TiO2    EDTA       5 min, of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;14 TiO2    EDTA       After 5 min. of light irradiation,                                Film having a thickness of about 40                                &#956;m               No deposit               left for 60 hours.15 TiO2    TEA        5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;16 TiO2    TEA        After 5 min. of light irradiation,                                Film having a thickness of about 30                                &#956;m               No deposit               left for 60 hours.17 TiO2    Tart       5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;18 TiO2    Tart       After 5 min. of light irradiation,                                Film having a thickness of about 15                                &#956; m              No deposit               left for 60 hours.19 ZnO   EDTA       5 min. of light irradiation                                Joined semipherical particles with                                &#966; of            No deposit                                several hundreds &#8491;20 ZnO   EDTA       After 5 min. of light irradiation,                                Film having a thickness of about 30                                &#956;m               No deposit               left for 60 hours.21 Zno   TEA        5 min. of light irradiation                                Joined semipherical particles with                                &#966; of            No deposit                                several hundreds &#8491;22 ZnO   TEA        After 5 min. of light irradiation,                                Film having a thickness of about 30                                &#956;m               No deposit               left for 60 hours.23 ZnO   Tart       5 min. of light irradiation                                Joined semipherical particles with                                &#966; of            No deposit                                several hundreds &#8491;24 ZnO   Tart       After 5 min. of light irradiation,                                Film having a thickness of about 15                                &#956;m               No deposit               left for 60 hours.__________________________________________________________________________
Example 3 Example 1 was repeated for degreasing, etching, rinsing and drying twelve alumina substrates (Nos. 25 to 36). Substrates Nos. 25 to 30 were then dipped in 100 ml of ethanol solution containing 0.1 mol of titanium tetraisopropoxide (Ti(O-i-C3 H7)4), and fired at 500� C. for an hour to yield alumina substrates carrying TiO2. Substrates Nos, 31 to 36 were dipped in an aqueous solution containing a thiourea complex of cadmium at a concentration of 0.05 mol/l, and fired at 400� C. for an hour to yield alumina substrates carrying CdS.
TABLE 4__________________________________________________________________________    Electroless copper          Structure of copper deposit   Semi- plating solution                                Portion notNo.   conductor    type       Plating conditions                                Portion irradiated with                                                    irradiated__________________________________________________________________________25 TiO2    EDTA       5 min. of light irradiation                                Joined semipherical particles with                                &#966; of            No deposit                                several hundreds &#8491;26 TiO2    EDTA       After 5 min. of light irradiation,                                Film having a thickness of about 80                                &#956;m               No deposit               left for 60 hours27 TiO2    TEA        5 min. of light irradiation                                Joined semipherical particles with                                &#966; of            No deposit                                several hundreds &#8491;28 TiO2    TEA        After 5 min. of light irradiation,                                Film having a thickness of about 50                                &#956;m               No deposit               left for 60 hours29 TiO2    Tart       5 min. of light irradiation                                Joined semipherical particles with                                &#966; of            No deposit                                several hundreds &#8491;30 TiO2    Tart       After 5 min. of light irradiation,                                Film having a thickness of about 30                                &#956;m               No deposit               left for 60 hours31 CdS   EDTA       5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;32 CdS   EDTA       After 5 min. of light irradiation,                                Film having a thickness of about 20                                &#956;m               No deposit               left for 60 hours33 CdS   TEA        5 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;34 Cd$   TEA        After 5 min. of light irradiation,                                Film having a thickness of about 20                                &#956;m               No deposit               left for 60 hours35 CdS   Tart       5 min. of light irradiation                                Joined semipherical particles with                                &#966; of            No deposit                                several hundreds &#8491;36 CdS   Tart       After 5 min. of light irradiation,                                Island like semipherical particles                                with &#966;          No deposit               left for 60 hours                                of several hundreds__________________________________________________________________________                                &#8491;
Example 4 Example 1 was repeated for degreasing, etching, rinsing and drying 10 alumina substrates (Nos. 37 to 46). The method employed for sample No. 1 in Example 1 was repeated for forming TiO2 on substrates Nos. 37 and 38. The method employed for sample No. 31 in Example 3 was repeated for forming CdS on substrates Nos. 39 to 42. Sputtering, which had been employed for sample No. 19 in Example 3, was employed for forming ZnO and SiC on substrates Nos. 43 and 44, and Nos. 45 and 46, respectively.
TABLE 5______________________________________          Composition          of electroless plating solution          Nickel    Cobalt______________________________________Concentration ofsacrificial reagent (mol/l)Cit              0.2         --Tart             --          0.5Concentration ofnickel or cobalt salt (mol/l)NiCl2       0.1         --CoSO4       --          0.08Sodium phosphinate (mol/l)            0.1         0.1Boric acid (mol/l)            --          0.5______________________________________
TABLE 6__________________________________________________________________________    Electroless copper          Structure of copper deposit   Semi- plating solution                                Portion notNo.   conductor    type       Plating conditions                                Portion irradiated with                                                    irradiated__________________________________________________________________________37 TiO2    Cit nickel 15 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;38 TiO2    Cit nickel After 15 min. of light irradiation,                                Film having a thickness of about 10                                &#956;m               No deposit               left for 60 hours.39 CdS   Cit nickel 15 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;40 CdS   Cit nickel After 15 min. of light irradiation,                                Film having a thickness of about 10                                &#956;m               No deposit               left for 60 hours.41 CdS   Tart cobalt               20 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;42 CdS   Tart cobalt               After 20 min. of light irradiation,                                Film having a thickness of about 10                                &#956;m               No deposit               left for 60 hours.43 ZnO   Cit nickel 15 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;44 ZnO   Cit nickel After 15 min. of light irradiation,                                Film having a thickness of about 10                                &#956;m               No deposit               left for 60 hours.45 SiC   Tart cobalt               20 min. of light irradiation                                Island like semipherical particles                                with &#966;          No deposit                                of several hundreds &#8491;46 SiC   Tart cobalt               After 20 min. of light irradiation,                                Film having a thickness of about 10                                &#956;m               No deposit               left for 60 hours.__________________________________________________________________________
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4151311 *Sep 16, 1977Apr 24, 1979Nathan FeldsteinPost colloid addition of catalytic promoters to non noble metal principal catalytic compounds in electroless plating catalystsUS4359485 *May 1, 1981Nov 16, 1982Bell Telephone Laboratories, IncorporatedRadiation induced deposition of metal on semiconductor surfacesUS4419390 *Sep 29, 1980Dec 6, 1983Nathan FeldsteinMetal ion promoter, reducing agentsUS4472458 *Jan 13, 1983Sep 18, 1984Bayer AktiengesellschaftReduction of organometallic compounds, then electroless depositionUS4661372 *Dec 23, 1985Apr 28, 1987General Motors CorporationUV-induced copper-catalyzed electroless deposition onto styrene-derivative polymer surfaceUS4738869 *Nov 24, 1986Apr 19, 1988Pacific BellPhotoselective electroless plating method employing UV-absorbing substratesUS4910049 *Dec 15, 1986Mar 20, 1990International Business Machines CorporationConditioning a dielectric substrate for plating thereonUS5314725 *Feb 17, 1993May 24, 1994Kabushiki Kaisha Toyota Chuo KenkyushoPhoto-plating processJPS5717479A * Title not availableJPS63157314A * Title not available* Cited by examinerNon-Patent CitationsReference1 *Kirk Othmer Encyclopedia of Chemical Technology vol. 8, 3rd ed. John Wiley & Sons 1979, pp. 738 741.2Kirk-Othmer "Encyclopedia of Chemical Technology" vol. 8, 3rd ed. John Wiley & Sons 1979, pp. 738-741.3M. Paunovic "Electrochemical Aspects of Electroless Deposition of Metals" Plating, Nov. 1968, pp. 1161-1167.4 *M. Paunovic Electrochemical Aspects of Electroless Deposition of Metals Plating, Nov. 1968, pp. 1161 1167.* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS5830805 *Nov 18, 1996Nov 3, 1998Cornell Research FoundationElectroless deposition equipment or apparatus and method of performing electroless depositionUS5834069 *Apr 30, 1996Nov 10, 1998Zentox CorporationIlluminating catalyst in the presence of a suitable source of metal to deposit the metal on the illuminated portionUS5882435 *Jul 7, 1997Mar 16, 1999Siemens Solar GmbhMetal coating on solar cells, dielectrics, patterns, silicon with n-dopes, trench patterns and metal structureUS6165912 *Sep 14, 1999Dec 26, 2000Cfmt, Inc.Electroless metal deposition of electronic components in an enclosable vesselUS6225221Feb 10, 2000May 1, 2001Chartered Semiconductor Manufacturing Ltd.Method to deposit a copper seed layer for dual damascene interconnectsUS6248658 *Jan 13, 1999Jun 19, 2001Advanced Micro Devices, Inc.Method of forming submicron-dimensioned metal patternsUS6607981 *Sep 7, 2000Aug 19, 2003Nec CorporationMethod for forming a Cu interconnect patternUS6624070 *Oct 24, 2001Sep 23, 2003Shipley Company, L.L.C.Plating catalystsWO2005125291A1 *May 27, 2005Dec 29, 2005Patrick LinderElimination of copper for producing strip conductorsWO2012036760A1 *Mar 11, 2011Mar 22, 2012Specmat, Inc.Method, process and fabrication technology for high-efficency low-cost crytalline silicon solar cells* Cited by examinerClassifications U.S. Classification438/678, 427/553, 427/581, 427/443.1, 427/443.2International ClassificationH01L21/288, H05K3/18, C23C18/14, C23C18/16Cooperative ClassificationC23C18/161, C23C18/31, C23C18/1612, C23C18/1642, H05K3/185European ClassificationH05K3/18B2C, C23C18/16B2Legal EventsDateCodeEventDescriptionAug 12, 2003FPExpired due to failure to pay maintenance feeEffective date: 20030613Jun 13, 2003LAPSLapse for failure to pay maintenance feesJan 2, 2003REMIMaintenance fee reminder mailedDec 7, 1998FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google