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(12) United States Patent 20Um USO08057654B2 (12) United States Patent (10) Patent No.: US 8,057,654 B2 M00re et al. (45) Date of Patent: Nov. 15, 2011 (54) ELECTRODEPOSITION OF DIELECTRIC 3,793,278 A 2f1974 De Bona COATINGS ON SEMCONDUCTIVE 3,928, 157 A 12/1975 Suematsu et al. 3,947.338 A 3, 1976 Jerabek et al. SUBSTRATES 3,947,339 A 3, 1976 Jerabek et al. 3,962,165 A 6, 1976 Bosso et al. (75) Inventors: Kelly L. Moore, Dunbar, PA (US); Michael J. Pawlik, Glenshaw, PA (US); (Continued) Michael G. Sandala, Pittsburgh, PA (US); Craig A. Wilson, Allison Park, PA FOREIGN PATENT DOCUMENTS (US) EP OO12463 A1 6, 1980 (73) Assignee: PPG Industries Ohio, Inc., Cleveland, OTHER PUBLICATIONS OH (US) Kohler, E. P. "An Apparatus for Determining Both the Quantity of (*) Notice: Subject to any disclaimer, the term of this Gas Evolved and the Amount of Reagent Consumed in Reactions patent is extended or adjusted under 35 with Methyl Magnesium Iodide'. J. Am. Chem. Soc., 1927, 49 (12), U.S.C. 154(b) by 345 days. 3181-3188, American Chemical Society, Washington, D.C. (21) Appl. No.: 12/405,299 Primary Examiner — Alexa Neckel (22) Filed: Mar 17, 2009 Assistant Examiner — Brian Cohen (65) Prior Publication Data (74) Attorney, Agent, or Firm — Robert P. Lenart US 2009/O236231 A1 Sep. 24, 2009 (57) ABSTRACT Related U.S. Application Data A method includes: immersing a semiconductive Substrate in (60) Provisional application No. 61/037,814, filed on Mar. an electrodeposition composition, wherein at least 20 percent 19, 2008. by weight of resin Solids in the composition is a highly cross (51) Int. Cl. linked microgel component, and applying a Voltage between C25D I3/04 (2006.01) the Substrate and the composition to form a dielectric coating C25D 9/02 (2006.01) on the Substrate. A composition for use in electrodeposition C25D 7/12 (2006.01) includes a resin blend, a coalescing solvent, a catalyst, water, (52) U.S. Cl. ......... 204/471; 205/157: 205/317; 204/500 and a highly cross-linked migrogel, wherein at least 20 per (58) Field of Classification Search .................. 204/501, cent by weight of resin Solids in the composition is the highly 204/504, 509, 492,493 cross-linked microgel. Another composition for use in elec See application file for complete search history. trodeposition includes a surfactant blend, a low ion polyol. phenoxypropanol, a catalyst, water, a flexibilizer, and a (56) References Cited highly cross-linked migrogel, wherein at least 20 percent by weight of resin Solids in the composition is the highly cross U.S. PATENT DOCUMENTS linked microgel. 3,455,806 A 7/1969 Spoor et al. 3,663,389 A 5, 1972 Koral et al. 3,749,657 A 7, 1973 Le Bras et al. 21 Claims, 2 Drawing Sheets 14 20 2-10 12 H 20um US 8,057,654 B2 Page 2 U.S. PATENT DOCUMENTS 5,096,556 A 3/1992 Corrigan et al. 3,975,346 A 8, 1976 Bosso et al. 5,371,120 A ck 12, 1994 Uhlianuk ...................... 523,414 3,984.299 A 10, 1976 Jerabek 6,165.338 A 12/2000 December et al. 3984922 A 10, 1976 E. e 7,674,846 B2 * 3/2010 Chung et al. .................. 523,415 - w OS 2006, O141 143 A1 6/2006 McCollum et al. 4,001,101 A 1/1977 Bosso et al. 4,116,900 A 9/1978 Belanger 4,134,932 A 1/1979 Kempter et al. * cited by examiner U.S. Patent Nov. 15, 2011 Sheet 1 of 2 US 8,057,654 B2 14 20 12 H 20um FIG. 1 32 26 24 H 20um FIG 2 . 44 2-34 36 H 20um FIG 3 U.S. Patent Nov. 15, 2011 Sheet 2 of 2 US 8,057,654 B2 50 56 --Cs ? 2- -46 52 54 48 H 20um FIG. 4 62 68 // -58 64 66 60 H 20um FIG. 5 74 80 f -70 72 H 20m FIG. 6 US 8,057,654 B2 1. 2 ELECTRODEPOSITION OF DELECTRIC There is a need for a conformal dielectric coating that can COATINGS ON SEMCONDUCTIVE form an insulating layer that adequately insulates semicon SUBSTRATES ductive materials. CROSS-REFERENCE TO ARELATED SUMMARY OF THE INVENTION APPLICATION In a first aspect, the present invention is directed toward a This application claims the benefit of U.S. Provisional method for depositing a coating on a semiconductive Sub Patent Application Ser. No. 61/037,814, filed Mar. 19, 2008, strate. The method includes: immersing a semiconductive and titled “Electrodeposition Of Dielectric Coatings On 10 Substrate in an electrodeposition composition, wherein at Semiconductive Materials”, which is hereby incorporated by least 20 percent by weight of resin solids in the composition reference. is a highly cross-linked microgel component, and applying a Voltage between the Substrate and the composition to form a FIELD OF THE INVENTION dielectric coating on the Substrate. 15 In another aspect, the invention provides a composition for use in electrodeposition including a resin blend, a coalescing The present invention relates to methods and compositions Solvent, a catalyst, water, and a highly cross-linked migrogel, for coating semiconductive materials. wherein at least 20 percent by weight of resin solids in the composition is the highly cross-linked microgel. BACKGROUND OF THE INVENTION In another aspect, the invention provides a composition for use in electrodeposition including a surfactant blend, a low Various electronic devices are constructed of semiconduc ion polyol, phenoxypropanol, a catalyst, water, a flexibilizer, tive materials. In the fabrication of Such devices, insulating and a highly cross-linked migrogel, wherein at least 20 per materials. Such as dielectric materials, may be formed on cent by weight of resin Solids in the composition is the highly Surfaces of the semiconductive materials. 25 cross-linked microgel. Dielectric coatings can be applied using electrodeposition (ED). During aqueous electrodeposition, electricity flows BRIEF DESCRIPTION OF THE DRAWINGS through the material being coated (electrode) and attracts charged particles which are dispersed in the electrodeposition FIGS. 1-6 are schematic representations of substrates bath. At the surface of the material being coated, electrolysis 30 coated using the compositions of Examples I-VI. of water occurs. If the material being coated is serving as the anode, protons are formed at the surface which will then react DETAILED DESCRIPTION OF THE INVENTION with negatively charged coating particles (anodic ED). If the material being coated is serving as the cathode, hydroxide In one aspect, the present invention is directed to a method ions are formed at the surface which will then react with 35 for preparing a circuit assembly. The method includes: immersing a semiconductive Substrate in an electrodeposi positively charged coating particles (cathodic ED). If elec tion composition, wherein at least 20 percent by weight of tricity flows easily through the electrode (conductive mate resin Solids in the composition is a highly cross-linked micro rial), the process is more efficient (i.e., there is more deposited gel component, and applying a voltage between the Substrate film for a given set of coating conditions) than for a semicon 40 and the composition to form a dielectric coating on the Sub ductive or weakly conductive material. Strate. For cathodic ED, the positively charged paint particles are The semiconductive material can be, for example, a Group neutralized by the hydroxide ions at the Surface, causing the IV elemental semiconductor, a Group IV compound semi particles to become insoluble in water and collect on the conductor, a Group III-V semiconductor, a Group III-V ter surface of the cathode. The neutralized particles then coalesce 45 nary semiconductor alloy, a Group III-V quaternary semicon into a continuous film on the Surface forming an insulating ductor alloy, a Group III-V quinary semiconductor alloy, a layer. As the insulation increases, electrodeposition gradually Group II-VI semiconductor, a Group II-VI ternary alloy semi decreases and then (eventually) stops. conductor, a Group I-VII semiconductor, a Group IV-VI Electrocoating has the ability to completely coat all kinds semiconductor, a Group IV-VI ternary semiconductor, a of components (inside and out) that conventional spray/brush 50 Group V-VI semiconductor, a Group II-V semiconductor, processes cannot. It also has the potential to coat many dif layered semiconductors, or other semiconductors, including ferent geometries including parts with acute angles, Small organic semiconductors and magnetic semiconductors. holes, and sharp edges. Sharp edges have a naturally higher Group IV elemental semiconductors include Diamond (C), potential to attract charged coating particles than flat Surfaces. Silicon (Si), and Germanium (Ge). Group IV compound Thus sharp edges tend to have a higher “wet film' build than 55 semiconductors include Silicon carbide (SiC), and Silicon the neighboring flat surfaces. However, Surface tension germanide (SiGe). Group III-V semiconductors include Alu effects tend to pull the coating away from the sharp edge(s) minium antimonide (AISb), Aluminium arsenide (AlAS), during flow/cure. In addition, Surface tension varies from Aluminium nitride (AIN), Aluminium phosphide (AlP), Substrate to Substrate. Higher coating thickness will tend to Boron nitride (BN). Boron phosphide (BP), Boron arsenide help ensure that the edges will maintain some coverage. 60 (BAs), Gallium antimonide (GaSb), Gallium arsenide Higher film thicknesses on the sharp edges of conductive (GaAs), Gallium nitride (GaN), Gallium phosphide (GaP), substrates can easily be obtained with commercial ED coat Indium antimonide (InSb), Indium arsenide (InAs), Indium ings due to the efficient flow of electricity with these sub nitride (InN), and Indium phosphide (InP). Group III-V ter strates. The result is Sufficient edge coverage. However, since nary semiconductor alloys include Aluminium gallium ars semiconductive and weakly conductive Substrates have 65 enide (AlGaAs, AlGaAs), Indium gallium arsenide (In greater difficulty building thicker films, these substrates may GaAs, InGaAs), Indium gallium phosphide (InGaP), not obtain sufficient edge coverage with standard E-coats.
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