Semiconductor device with resistance circuit

Abstract

Provided is a resistance circuit having a resistance element with high resistance and high accuracy. An insulating film such as a silicon nitride film is formed on the resistance element made of a thin film material whose thickness is reduced to 500 Å or smaller. The insulating film prevents passing through of the contact hole arranged on the resistance element during etching for forming the contact hole.

1 . A semiconductor device, comprising:
 a resistance circuit; and   an insulated gate field effect transistor, the resistance circuit comprising:
 a resistance element formed of a first thin film arranged on an isolation oxide film provided on a surface of a semiconductor substrate; 
 a second thin film formed on the resistance element; 
 an intermediate insulating film formed on the second thin film; 
 a contact hole for the resistance element, the contact hole passing through the second thin film and being provided in the intermediate insulating film at a depth reaching the first thin film; and 
 a metal wiring formed on the contact hole; 
   wherein the insulated gate field effect transistor is provided in a region of the semiconductor substrate surrounded by the isolation oxide film.   
     
     
         2 . A semiconductor device according to  claim 1 , wherein the second thin film is formed on the first thin film and has the same shape in plan view as the resistance element formed of the first thin film. 
     
     
         3 . A semiconductor device according to  claim 1 , wherein the second thin film is formed on the first thin film and is formed in separated regions each including the contact hole. 
     
     
         4 . A semiconductor device according to  claim 1 , wherein the second thin film is formed on the first thin film and is formed in a region including the resistance element formed of the first thin film, the region being wider than the resistance element. 
     
     
         5 . A semiconductor device according to  claims 1 , wherein the first thin film has a thickness of 500 Å or smaller. 
     
     
         6 . A semiconductor device according to  claims 1 , wherein:
 the first thin film comprises a first polycrystalline silicon film; and   the first polycrystalline silicon film contains impurities of a first conductivity type at an impurity concentration in a range of 1×10 15  atoms/cm 3  to 5×10 19  atoms/cm 3 .   
     
     
         7 . A semiconductor device according to  claims 1 , wherein the first thin film comprises a thin film made of one of CrSi, CrSiN, CrSiO, NiCr, and TiN. 
     
     
         8 . A semiconductor device according to  claims 1 , wherein the second thin film comprises a silicon nitride film. 
     
     
         9 . A semiconductor device according to  claim 6 , wherein the second thin film comprises a second polycrystalline silicon film containing impurities of a second conductivity type, which is opposite to the first conductivity type of the first polycrystalline silicon film. 
     
     
         10 . A semiconductor device according to  claim 6 , wherein the second thin film comprises a second polycrystalline silicon film which does not contain impurities. 
     
     
         11 . A semiconductor device according to  claim 8 , wherein the second thin film has a thickness in a range of 150 Å to 350 Å.