Semiconductor device and its manufacturing method

Abstract

A mark is formed over the surface of a silicon substrate. The mark includes a silicon oxide film, in which a plurality of rectangular groove patterns are concentrically arranged, and a silicon nitride film formed in the groove patterns. A P-type epitaxial layer is formed over the surface of the silicon substrate. Then, a photoresist pattern is formed. In the photoresist pattern, a rectangular opening pattern is formed in a mark region. Optical superposition inspection is performed for the base of the photoresist pattern.

What is claimed is: 
     
         1 . A semiconductor device comprising:
 a crystal substrate;   a mark which is formed in a first region in the crystal substrate;   a crystal layer which is formed over the crystal substrate excluding a region where the mark is arranged; and   an interlayer insulating film which is formed to cover the mark and the crystal layer,   wherein the mark includes
 a first insulating film which has a groove pattern, and 
 a second insulating film which is formed in the groove pattern and has a material different from that of the first insulating film. 
   
     
     
         2 . The semiconductor device according to  claim 1 ,
 wherein an upper surface of the second insulating film is in a position lower than an upper surface of the first insulating film.   
     
     
         3 . The semiconductor device according to  claim 1 ,
 wherein a lower surface of the second insulating film is in a position higher than a lower surface of the first insulating film.   
     
     
         4 . The semiconductor device according to  claim 1 ,
 wherein a lower surface of the second insulating film is in a position lower than a lower surface of the first insulating film.   
     
     
         5 . The semiconductor device according to  claim 1 , further comprising
 a high withstand voltage transistor which is formed in a second region in the crystal layer, and   wherein the interlayer insulating film is formed to cover the high withstand voltage transistor.   
     
     
         6 . The semiconductor device according to  claim 1 ,
 wherein the first insulating film is any one of a silicon oxide film and a silicon nitride film, and   wherein the second insulating film is other one of the silicon oxide film and the silicon nitride film.