US0083.33879B2 (12) United States Patent (10) Patent No.: US 8,333,879 B2 M00re et al. (45) Date of Patent: Dec. 18, 2012 (54) ELECTRODEPOSITION OF DELECTRIC (56) References Cited COATINGS ON SEMCONDUCTIVE SUBSTRATES U.S. PATENT DOCUMENTS 3,455,806 A 7/1969 Spoor et al. (75) Inventors: Kelly L. Moore, Dunbar, PA (US); 3,663,389 A 5, 1972 Koral et al. Michael J. Pawlik, Glenshaw, PA (US); 3,749,657 A 7, 1973 Le Bras et al. Michael G. Sandala, Pittsburgh, PA 3,793,278 A 2f1974 De Bona (US); Craig A. Wilson, Allison Park, PA 3,928, 157 A 12/1975 Suematsu et al. 3,947.338 A 3, 1976 Jerabek et al. (US) 3,947,339 A 3, 1976 Jerabek et al. 3,962,165 A 6, 1976 Bosso et al. (73) Assignee: PPG Industries Ohio, Inc., Cleveland, 3,975,346 A 8, 1976 Bosso et al. OH (US) 3,984,299 A 10, 1976 Jerabek (*) Notice: Subject to any disclaimer, the term of this (Continued) patent is extended or adjusted under 35 FOREIGN PATENT DOCUMENTS U.S.C. 154(b) by 0 days. EP OO12463 A1 6, 1980 (21) Appl. No.: 13/240,455 OTHER PUBLICATIONS (22) Filed: Sep. 22, 2011 Kohler, E. P. "An Apparatus for Determining Both the Quantity of Gas Evolved and the Amount of Reagent Consumed in Reactions (65) Prior Publication Data with Methyl Magnesium Iodide'. J. Am. Chem. Soc., 1927, 49 (12), US 2012/OOO6683 A1 Jan. 12, 2012 3181-3188, American Chemical Society, Washington, D.C. Related U.S. Application Data Primary Examiner — Milton I Cano Assistant Examiner — Brian W Cohen (62) Division of application No. 12/405,299, filed on Mar. (74) Attorney, Agent, or Firm — Robert P. Lenart 17, 2009, now Pat. No. 8,057,654. (60) Provisional application No. 61/037,814, filed on Mar. (57) ABSTRACT 19, 2008. A composition for use in electrodeposition includes a resin blend, a coalescing solvent, a catalyst, water, and a highly (51) Int. C. cross-linked microgel, wherein at least 20 percent by weight C09D 5/44 (2006.01) of resin Solids in the composition is the highly cross-linked C25D I3/04 (2006.01) microgel. Another composition for use in electrodeposition C25D 9/02 (2006.01) includes a Surfactant blend, a low ion polyol, phenoxypro C25D 7/12 (2006.01) panol, a catalyst, water, a flexibilizer, and a highly cross (52) U.S. C. ........ 204/489: 205/157: 205/317; 204/500; linked microgel, wherein at least 20 percent by weight of 204/471; 204/508 resin Solids in the composition is the highly cross-linked (58) Field of Classification Search .................. 204/471, microgel. 204/500, 508; 205/157,317 See application file for complete search history. 8 Claims, 2 Drawing Sheets 10 20um US 8,333.879 B2 Page 2 U.S. PATENT DOCUMENTS 5,096,556 A 3/1992 Corrigan et al. 3,984,922 A 10, 1976 Rosen 5,371,120 A 12/1994 Uhlianuk 4,001,101 A 1/1977 Bosso et al. 6,165.338 A 12/2000 December et al. 4,116,900 A 9/1978 Belanger 7,674,846 B2 3/2010 Chung et al. 4,134,932 A 1/1979 Kempter et al. 2006, O141 143 A1 6/2006 McCollum et al. U.S. Patent Dec. 18, 2012 Sheet 1 of 2 US 8,333,879 B2 14 20 --- // -2- O t le 12 26.Lim FIG. 1 32 20um FIG 3 U.S. Patent Dec. 18, 2012 Sheet 2 of 2 US 8,333,879 B2 50 56 ------ - W -- F- - 46 52 u/ 54 48 - - 20Lum FIG. 4 74 80 70 76 78 -21 72 20pum FIG. 6 US 8,333,879 B2 1. 2 ELECTRODEPOSITION OF DELECTRIC semiconductive and weakly conductive Substrates have COATINGS ON SEMCONDUCTIVE greater difficulty building thicker films, these substrates may SUBSTRATES not obtain sufficient edge coverage with standard E-coats. There is a need for a conformal dielectric coating that can CROSS-REFERENCE TO ARELATED form an insulating layer that adequately insulates semicon APPLICATION ductive materials. This application is a divisional patent application of U.S. SUMMARY OF THE INVENTION patent application Ser. No. 12/405,299, U.S. Pat. No. 8,057, 654 filed Mar. 17, 2009, and titled “Electrodeposition of 10 In a first aspect, a composition for use in electrodeposition Dielectric Coatings on Semiconductive Materials”, which is includes a resin blend, a coalescing solvent, a catalyst, water, hereby incorporated by reference. U.S. patent application Ser. and a highly cross-linked migrogel, wherein at least 20 per No. 12/405,299 claims the benefit of U.S. Provisional Patent cent by weight of resin Solids in the composition is the highly Application Ser. No. 61/037,814, filed Mar. 19, 2008, and cross-linked microgel. titled “Electrodeposition of Dielectric Coatings on Semicon 15 In another aspect, a composition for use in electrodeposi ductive Materials, which is hereby incorporated by refer tion includes a Surfactant blend, a low ion polyol, phenox CCC. ypropanol, a catalyst, water, a flexibilizer, and a highly cross linked migrogel, wherein at least 20 percent by weight of FIELD OF THE INVENTION resin Solids in the composition is the highly cross-linked microgel. The present invention relates to methods and compositions for coating semiconductive materials. BRIEF DESCRIPTION OF THE DRAWINGS BACKGROUND OF THE INVENTION FIGS. 1-6 are schematic representations of substrates 25 coated using the compositions of Examples I-VI. Various electronic devices are constructed of semiconduc tive materials. In the fabrication of Such devices, insulating DETAILED DESCRIPTION OF THE INVENTION materials. Such as dielectric materials, may be formed on Surfaces of the semiconductive materials. In one aspect, the present invention is directed to a method Dielectric coatings can be applied using electrodeposition 30 for preparing a circuit assembly. The method includes: (ED). During aqueous electrodeposition, electricity flows immersing a semiconductive Substrate in an electrodeposi through the material being coated (electrode) and attracts tion composition, wherein at least 20 percent by weight of charged particles which are dispersed in the electrodeposition resin Solids in the composition is a highly cross-linked micro bath. At the surface of the material being coated, electrolysis gel component, and applying a voltage between the Substrate of water occurs. If the material being coated is serving as the 35 and the composition to form a dielectric coating on the Sub anode, protons are formed at the surface which will then react Strate. with negatively charged coating particles (anodic ED). If the The semiconductive material can be, for example, a Group material being coated is serving as the cathode, hydroxide IV elemental semiconductor, a Group IV compound semi ions are formed at the surface which will then react with conductor, a Group III-V semiconductor, a Group III-V ter positively charged coating particles (cathodic ED). If elec 40 nary semiconductor alloy, a Group III-V quaternary semicon tricity flows easily through the electrode (conductive mate ductor alloy, a Group III-V quinary semiconductor alloy, a rial), the process is more efficient (i.e., there is more deposited Group II-VI semiconductor, a Group II-VI ternary alloy semi film for a given set of coating conditions) than for a semicon conductor, a Group I-VII semiconductor, a Group IV-VI ductive or weakly conductive material. semiconductor, a Group IV-VI ternary semiconductor, a For cathodic ED, the positively charged paint particles are 45 Group V-VI semiconductor, a Group II-V semiconductor, neutralized by the hydroxide ions at the Surface, causing the layered semiconductors, or other semiconductors, including particles to become insoluble in water and collect on the organic semiconductors and magnetic semiconductors. surface of the cathode. The neutralized particles then coalesce Group IV elemental semiconductors include Diamond (C), into a continuous film on the Surface forming an insulating Silicon (Si), and Germanium (Ge). Group IV compound layer. As the insulation increases, electrodeposition gradually 50 semiconductors include Silicon carbide (SiC), and Silicon decreases and then (eventually) stops. germanide (SiGe). Group III-V semiconductors include Alu Electrocoating has the ability to completely coat all kinds minium antimonide (AISb), Aluminium arsenide (AlAS), of components (inside and out) that conventional spray/brush Aluminium nitride (AIN), Aluminium phosphide (AlP), processes cannot. It also has the potential to coat much dif Boron nitride (BN). Boron phosphide (BP), Boron arsenide ferent geometry including parts with acute angles, Small 55 (BAs), Gallium antimonide (GaSb), Gallium arsenide holes, and sharp edges. Sharp edges have a naturally higher (GaAs), Gallium nitride (GaN), Gallium phosphide (GaP), potential to attract charged coating particles than flat Surfaces. Indium antimonide (InSb), Indium arsenide (InAs), Indium Thus, sharp edges tend to have a higher “wet film' build than nitride (InN), and Indium phosphide (InP). Group III-V ter the neighboring flat surfaces. However, Surface tension nary semiconductor alloys include Aluminium gallium ars effects tend to pull the coating away from the sharp edge(s) 60 enide (AlGaAs, AlGaAs), Indium gallium arsenide (In during flow/cure. In addition, Surface tension varies from GaAs, InGaAs), Indium gallium phosphide (InGaP). Substrate to Substrate. Higher coating thickness will tend to Aluminium indium arsenide (AlInAs), Aluminium indium help ensure that the edges will maintain some coverage. antimonide (AlInSb), Gallium arsenide nitride (GaAsN), Higher film thicknesses on the sharp edges of conductive Gallium arsenide phosphide (GaAsP), Aluminium gallium substrates can easily be obtained with commercial ED coat 65 nitride (AlGaN), Aluminium gallium phosphide (AlGaP), ings due to the efficient flow of electricity with these sub Indium gallium nitride (InGaN), Indium arsenide antimonide strates. The result is Sufficient edge coverage. However, since (InAsSb), and Indium gallium antimonide (InGaSb).