Semiconductor device and production thereof

Abstract

A semiconductor device produced by forming an oxide film on a substrate, heat treating the oxide film at a temperature of 800° C. or higher in an inert atmosphere, followed by conventional steps for formation of a transistor, is improved in electrical reliability due to relaxation of stress generated in the oxide film or in the surface of substrate.

What is claimed is:  
     
         1 . A process for producing a semiconductor device which comprises forming a thermal oxide film on a silicon substrate, and carrying out a heat-treatment at a temperature of not lower than 800° C. while keeping the oxide film and surface of silicon substrate in a bare state in an inert atmosphere, followed by introduction of impurities, formation of electrodes and wiring, and formation of an insulating film so as to form a transistor.  
     
     
         2 . A process for producing a semiconductor device which comprises, after completing the selective oxidation for forming an oxide film having a partially increased thickness on the surface of a silicon substrate for electrically insulating and isolating the semiconductor elements, removing the thin films other than the oxide film, carrying out a heat-treatment at a temperature of not lower than 950° C. while keeping the oxide film or silicon substrate in a bare state in an inert atmosphere, followed by formation of gate oxide film, introduction of impurities, formation of electrodes and wiring, formation of an insulating film so as to form a transistor.  
     
     
         3 . A process for producing a semiconductor device which comprises forming an oxide film having a partially increased thickness on the surface of a silicon substrate for electrically insulating and isolating the semiconductor elements, thereafter forming a gate oxide film of MOS type transistor and, just after completing the gate oxidation or after forming the gate electrodes, carrying out a heat-treatment at a temperature of not lower than 800° C. in an inert atmosphere, followed by introduction of impurities, formation of electrodes and wiring, formation of an insulating film so as to form a transistor.  
     
     
         4 . A semiconductor device obtained by forming a thermal oxide film, subsequently carrying out a heat treatment at a temperature of not lower than 800° C. while keeping the surface of the oxide film or silicon substrate in a bare state, followed by introduction of impurities, formation of electrodes and wiring, formation of an insulating film so as to form a transistor.  
     
     
         5 . A semiconductor device obtained by completing a selective oxidation for forming on the surface of a silicon substrate an oxide film having a partially increased thickness for electrically insulating and isolating semiconductor elements, thereafter removing the thin films other than the oxide film, carrying out a heat-treatment at a temperature of not lower than 950° C. while keeping the oxide film or silicon substrate in a bare state, followed by formation of a gate oxide film, introduction of impurities, formation of electrodes and wiring, and formation of an insulating film so as to form a transistor.  
     
     
         6 . A semiconductor device obtained by forming on the surface of a silicon substrate an oxide film having a partially increased thickness for electrically insulating and isolating semiconductor elements, thereafter forming a gate oxide film of MOS type transistor and, just after completion of the gate oxidation or after formation of gate electrodes, carrying out a heat-treatment at a temperature of not lower than 800° C., followed by introduction of impurities, formation of electrodes and wiring, formation of an insulating film so as to form a transistor.  
     
     
         7 . A semiconductor device according to  claim 4 , wherein said semiconductor device is a memory device selected from flash memory, DRAM, and SRAM or a computing device.  
     
     
         8 . A process for producing a semiconductor device according to  claim 1 , wherein said thermal oxidation is carried out at least in an atmosphere of a gaseous mixture of hydrogen and oxygen or in an atmosphere of H 2 O.  
     
     
         9 . A semiconductor device according to  claim 4 , wherein said thermal oxide film is obtained by carrying out oxidation at least in an atmosphere of a gaseous mixture of hydrogen and oxygen.  
     
     
         10 . A process for producing a semiconductor device according to  claim 1 , wherein the atmosphere of the heat-treatment is an inert gas selected from nitrogen, hydrogen and argon, or a gaseous mixture of these gases, said gas or gaseous mixture being able to contain 5% or less of oxygen.  
     
     
         11 . A semiconductor device according to  claim 4 , wherein the heat treated thermal oxide film is obtained by the heat-treatment in an inert gas selected from nitrogen, hydrogen and argon, or a gaseous mixture of these gases, said gas or gaseous mixture being able to contain 5% or less of oxygen.