Semiconductor structure and process thereof

Abstract

A semiconductor structure includes a substrate, a recess and a material. The recess is located in the substrate, wherein the recess has an upper part and a lower part. The minimum width of the upper part is larger than the maximum width of the lower part. The material is located in the recess.

1 . A semiconductor structure, comprising:
 a substrate;   a recess located in the substrate, wherein the recess has an upper part and a lower part, and the minimum width of the upper part is larger than the maximum width of the lower part; and   a material located in the recess.   
     
     
         2 . The semiconductor structure according to  claim 1 , wherein the connecting point of the upper part and the lower part has a turning point. 
     
     
         3 . The semiconductor structure according to  claim 1 , wherein the sidewalls of the upper part and the lower part respectively comprise an upward-broadened oblique sidewall. 
     
     
         4 . The semiconductor structure according to  claim 3 , wherein the acute angle between the oblique sidewall of the upper part and a level is larger than the acute angle between the oblique sidewall of the lower part and a level. 
     
     
         5 . The semiconductor structure according to  claim 4 , wherein the acute angle between the oblique sidewall of the upper part and a level is larger than 89°. 
     
     
         6 . The semiconductor structure according to  claim 1 , wherein the sidewall of the upper part is essentially vertical to a level. 
     
     
         7 . The semiconductor structure according to  claim 1 , wherein the material comprises oxide. 
     
     
         8 . The semiconductor structure according to  claim 1 , wherein the recess comprises a first predetermined depth and the upper part comprises a second predetermined depth. 
     
     
         9 . The semiconductor structure according to  claim 8 , wherein the first predetermined depth is 2000 angstroms and the second predetermined depth is 400 angstroms. 
     
     
         10 . The semiconductor structure according to  claim 8 , wherein the material fills a part of the recess below a third predetermined depth. 
     
     
         11 . The semiconductor structure according to  claim 10 , wherein the second predetermined depth is larger than the third predetermined depth. 
     
     
         12 . The semiconductor structure according to  claim 11 , wherein the first predetermined depth is 2000 angstroms, the second predetermined depth is 400 angstroms and the third predetermined depth is 250 angstroms. 
     
     
         13 . A semiconductor process, comprising:
 providing a substrate;   forming a recess in the substrate, wherein the recess has a first sidewall;   filling a material in the recess and exposing a part of the recess; and   performing an etching process to laterally etch the exposing part of the recess, therefore the recess comprises an upper part and a lower part, wherein the upper part has a second sidewall and the lower part has the first sidewall.   
     
     
         14 . The semiconductor process according to  claim 13 , wherein the connecting point of the upper part and the lower part has a turning point. 
     
     
         15 . The semiconductor process according to  claim 13 , wherein the first sidewall and the second sidewall are upward-broadened oblique sidewalls. 
     
     
         16 . The semiconductor process according to  claim 15 , wherein the acute angle between the second sidewall and a level is larger than the acute angle between the first sidewall and a level. 
     
     
         17 . The semiconductor process according to  claim 16 , wherein the acute angle between the second sidewall and a level is larger than 89°. 
     
     
         18 . The semiconductor process according to  claim 13 , wherein the second sidewall is essentially vertical to a level. 
     
     
         19 . The semiconductor process according to  claim 13 , wherein the recess has a first predetermined depth, and the part of the recess and the upper part have a second predetermined depth. 
     
     
         20 . The semiconductor process according to  claim 19 , wherein the first predetermined depth is 2000 angstroms and the second predetermined depth is 400 angstroms. 
     
     
         21 . The semiconductor process according to  claim 19 , wherein the steps of filling the material in the recess comprise:
 filling the material until the material is higher than the second predetermined depth; and   etching back the material until exposing the part of the recess with the second predetermined depth.   
     
     
         22 . The semiconductor process according to  claim 19 , after performing the etching process, further comprising:
 filling the material in the recess until exposing a part of the recess with a third predetermined depth.   
     
     
         23 . The semiconductor process according to  claim 22 , wherein the second predetermined depth is larger than the third predetermined depth. 
     
     
         24 . The semiconductor process according to  claim 23 , wherein the first predetermined depth is 2000 angstroms, the second predetermined depth is 400 angstroms and the third predetermined depth is 250 angstroms. 
     
     
         25 . The semiconductor process according to  claim 13 , wherein the etching process comprises a dry etching process. 
     
     
         26 . The semiconductor process according to  claim 25 , wherein the dry etching process comprises a tetrafluoromethane, helium and oxygen containing dry etching process.