Apparatus and method for manufacturing an integrated circuit

Abstract

The present invention relates to an apparatus for manufacturing an integrated circuit ( 10 ) having a thick film metal layer ( 14 ). A layer of metal paste ( 14 ) is applied via an application means ( 24 ) onto a heat-conducting substrate ( 12 ). The metal paste ( 14 ) includes metal particles of a predetermined size. An RF generator ( 16 ) selectively inductively couples RF energy ( 18 ) into the metal paste ( 14 ). The predetermined size of the metal particles of the metal paste ( 14 ) corresponds to a coupling frequency of the RF energy ( 18 ), for heating the metal particles. In this way the metal particles of the metal paste ( 14 ) are heated with only a small fraction of the power of conventional processes, and without the need to pre-sinter the metal paste ( 14 ).

1 . A method for manufacturing an integrated circuit having a thick film metal layer comprising the acts of:
 selectively applying a paste on a heat-conducting substrate using a applicator, the paste comprising particles of a metal constituent consisting essentially of metal particles having sizes within a single predetermined range about a single predetermined size; and   selectively inductively coupling a radio frequency (RF) energy into the metal particles of the paste from a radio frequency (RF) generator, the metal particles of the single predetermined size are selectively inductively couplable with the RF energy, for heating the metal particles, wherein the frequency of the RF energy corresponds to a coupling frequency of the metal particles of the single predetermined size so that the inductive heating of the metal particles is sufficient for melting the metal particles.   
     
     
         2 . The method  claim 1 , wherein the material of the substrate has a higher heat capacity than the paste comprising the particles. 
     
     
         3 . The method of  claim 1 , wherein the substrate comprises a semi-conductive material comprising at least one of silicon, gallium-arsenide, germanium, indium-tellurium compounds and copper-indium-gallium-sulfur compounds. 
     
     
         4 . The method of  claim 1 , wherein the substrate is a heat sink for rapidly cooling the selectively-coupled paste comprising the metal particles. 
     
     
         5 . The method of  claim 1 , wherein the metal particles comprise at least one of silver, aluminum, copper and stainless steel. 
     
     
         6 . The method of  claim 1 , wherein the coupling frequency is in the range from 2 to 200 MHz, so as to be inductively couplable with the metal particles. 
     
     
         7 . The method of  claim 1 , wherein the metal particles in the paste have a predetermined size in the range from 5 to 50 μm, so as to be inductively couplable with the RF energy. 
     
     
         8 . The apparatus of  claim 1 , wherein the predetermined range of particle size of the metal particles is within a range of 1 to 6 times a penetration depth of the RF energy in a material of the metal particles. 
     
     
         9 . The method of  claim 1 , comprising moving the substrate having the paste under the RF generator at a predetermined rate using a substrate table, wherein the RF energy is distributed in a predetermined manner. 
     
     
         10 . The method of  claim 9 , wherein the predetermined rate is constant and wherein the predetermined manner is variable and linked to the substrate position. 
     
     
         11 . The method of  claim 9 , wherein the predetermined rate is variable and wherein the predetermined manner is constant. 
     
     
         12 . The method of  claim 1 , comprising: pre-heating the substrate using a substrate heater, wherein the conduction properties of the substrate are dependent on temperature. 
     
     
         13 . The method of  claim 12 , wherein the substrate heater directly contacts the substrate. 
     
     
         14 . The method of  claim 12 , wherein the preheating includes heating the substrate above 400° C. 
     
     
         15 . The method of  claim 12 , wherein the substrate material has a critical temperature below which the substrate is not inductively heated by the radio frequency (RF) for inductively heating the metal particles and above which the substrate is inductively heated by the radio frequency (RF) for inductively heating the metal particles to increase the temperature of the substrate during the inductive heating of the metal particles, the temperature increase of the metal particles being more than the temperature increase of the substrate during the inductive heating, and wherein the preheating heats the substrate above the critical temperature. 
     
     
         16 . The method of  claim 1 , wherein the paste is applied onto the substrate with a predetermined three-dimensional geometry, wherein the temperature of the inductively coupled metal particles depends on the geometry of the paste. 
     
     
         17 . The method of  claim 1 , wherein the coupling frequency is 27 MHz. 
     
     
         18 . The method of  claim 1 , wherein the size of the particles of the metal constituent in the paste is selected to maximize the inductive heating of the particles. 
     
     
         19 . A non-transitive computer readable media encoded with instructions that when communicating with control apparatus for manufacturing an integrated circuit with a thick film metal layer perform the acts of a method for manufacturing the integrated circuit having the thick film metal layer, the acts comprising:
 using an applicator to selectively apply paste on a heat-conducting substrate, the paste comprising particles of a metal constituent consisting essentially of particles having sizes within a predetermined range about a predetermined size; and   using a radio frequency (RF) generator to selectively inductively couple radio frequency (RF) energy into the metal particles of the paste, the metal particles of the predetermined size are selectively inductively couplable with the RF energy, for heating the metal particles, and wherein the frequency of the RF energy corresponds to a coupling frequency of the metal particles of the paste so that the inductive heating of the metal particles is maximized.