Semiconductor device, e.g. field-effect transistor, and method of producing the same.

摘要

A semiconductor device comprising a semiconductor substrate (101) of a first conductive type having a first concentration of impurities therein; a first impurity layer (104) of said first conductive type which is formed in said semiconductor substrate (101) and which has a second concentration of impurities therein at a concentration higher than that of the said first concentration; a gate electrode (105) formed on said semiconductor substrate (101) by way of a first insulating film (103); a second impurity layer (106) of a second conductive type portions of which are formed in said semiconductor substrate (101) on opposite sides of said gate electrode (105) so as to be spaced apart from each other, the second impurity layer (106) having a third concentration of impurities therein; a side wall insulating film or films (108) each of which is formed on a side wall of said gate electrode (105); and a third impurity layer (109) of said second conductive type which is formed in said semiconductor substrate (101) laterally of said side wall insulating film or films (108), the third impurity layer (109) having a fourth concentration of impurities therein which is higher than said third concentration characterised in that the first impurity layer (104) is formed in the semiconductor substrate (101) so as to be spaced apart from a surface (101a) of the latter, the impurities in the first impurity layer (104) being at a first depth from the said surface (101a) of the semiconductor substrate (101), the second impurity layer (106) having impurities therein at a second depth from the said surface (101a) of the semiconductor substrate (101), the surface (106a) of the second impurity layer (106) which is lowermost when the said surface (101a) of the semiconductor substrate (101) is at the top of the device abutting the first impurity layer (104) or being disposed above the latter.