Semiconductor device and method for producing the same

Abstract

A semiconductor device includes: a first semiconductor region formed on a substrate and having an upper surface and a side surface; a first impurity region of a first conductivity type formed in an upper portion of the first semiconductor region; a second impurity region of a first conductivity type formed in a side portion of the first semiconductor region; and a gate insulating film formed so as to cover at least a side surface and an upper corner of a predetermined portion of the first semiconductor region. A radius of curvature r′ of an upper corner of a portion of the first semiconductor region located outside the gate insulating film is greater than a radius of curvature r of an upper corner of a portion of the first semiconductor region located under the gate insulating film and is less than or equal to 2r.

1 - 23 . (canceled) 
     
     
         24 . A method for producing a semiconductor device, comprising:
 a step (a) of forming on a substrate a first semiconductor region having an upper surface and a side surface; and   a step (b) of implanting the first semiconductor region with an impurity of a first conductivity type by a plasma doping method to thereby form a first impurity region in an upper portion of the first semiconductor region and a second impurity region in a side portion of the first semiconductor region,   wherein in the step (b), a pressure during plasma doping is set to be less than or equal to 0.6 Pa.   
     
     
         25 . The method for producing a semiconductor device of  claim 24 , wherein in the step (b), an implantation does of the second impurity region is greater than or equal to 80% of that of the first impurity region. 
     
     
         26 . The method for producing a semiconductor device of  claim 24 , further comprising, between the step (a) and the step (b), a step of forming a gate insulating film so as to cover at least a side surface and an upper corner of a predetermined portion of the first semiconductor region,
 wherein after the step (b), a radius of curvature r′ of an upper corner of a portion of the first semiconductor region located outside the gate insulating film is greater than a radius of curvature r of an upper corner of a portion of the first semiconductor region located under the gate insulating film and is less than or equal to 2r.   
     
     
         27 . The method for producing a semiconductor device of  claim 24 , wherein in the step (b), an ion current density during plasma doping is set to be less than or equal to 0.5 mA/cm 2 . 
     
     
         28 . The method for producing a semiconductor device of  claim 24 , wherein after the step (b), a sheet resistance of the second impurity region is less than or equal to 1.25 times that of the first impurity region. 
     
     
         29 . The method for producing a semiconductor device of  claim 24 , further comprising, before the step (a), a step of forming an insulating layer on the substrate,
 wherein the first semiconductor region is formed on the insulating layer in the step (a).   
     
     
         30 . The method for producing a semiconductor device of  claim 24 , wherein the side surface of the first semiconductor region is a surface perpendicular to the upper surface of the first semiconductor region. 
     
     
         31 . The method for producing a semiconductor device of  claim 24 , wherein:
 the step (b) is performed by using a plasma generated from a gas containing the impurity; and   the gas containing the impurity contains molecules B m H n  (m and n are natural numbers) composed of boron atoms and hydrogen atoms.   
     
     
         32 . The method for producing a semiconductor device of  claim 24 , wherein:
 the step (b) is performed by using a plasma generated from a gas containing the impurity; and   the gas containing the impurity is a gas obtained by diluting molecules including boron atoms with a rare gas.   
     
     
         33 . The method for producing a semiconductor device of  claim 24 , wherein:
 the step (b) is performed by using a plasma generated from a gas containing the impurity; and   a gas containing the impurity is a gas obtained by diluting molecules including the impurity with helium.   
     
     
         34 . The method for producing a semiconductor device of  claim 24 , wherein:
 the step (b) is performed by using a plasma generated from a gas containing the impurity; and   the gas containing the impurity is a mixed gas of B 2 H 6  and He.   
     
     
         35 . The method for producing a semiconductor device of  claim 34 , wherein a concentration by mass of B 2 H 6  in the mixed gas is greater than or equal to 0.01% and less than or equal to 1%. 
     
     
         36 . The method for producing a semiconductor device of  claim 24 , wherein:
 the step (b) is performed by using a plasma generated from a gas containing the impurity; and   the gas containing the impurity contains BF 3 .   
     
     
         37 . The method for producing a semiconductor device of  claim 24 , wherein:
 the step (b) is performed by using a plasma generated from a gas containing the impurity; and   the gas containing the impurity contains AsH 3  or PH 3 .   
     
     
         38 . A method for producing a semiconductor device, comprising a step of implanting a semiconductor region with an impurity of a first conductivity type by a plasma doping method to from an impurity region in the semiconductor region,
 wherein in the step of forming the impurity region, a pressure during plasma doping is set to be less than or equal to 0.6 Pa.