Method of producing semiconductor device having first and second type field effect transistors

A method of producing a semiconductor device having a first electrically conductive-type impurity layer as a first well and a second electrically conductive-type impurity layer as a second well which are formed adjacent each other on a main surface of a first electrically conductive-type semiconductor substrate, said method comprising the steps of:

• forming by ion implantation a first electrically conductive-type buried layer with an impurity concentration profile and am impurity concentration density greater than that of the first electrically conductive-type substrate in a region thereof underlying the first and second electrically conductive-type impurity regions,
• patterning a resist which opens with a predetermined width at a position corresponding to the boundary region between the first and second electrically conductive-type impurity layers on the first electrically conductive-type semiconductor substrate, and
• forming by ion implantation a high concentration impurity layer in the boundary region between the first and second electrically conductive-type impurity layers and from said main surface of said substrate to said buried layer by using said resist,
• wherein said high concentration impurity layer is formed so that a peak of its impurity concentration profile occurs below the main surface of the semiconductor substrate.

A method of producing a semiconductor device having a first electrically conductive-type impurity layer as a first well and a second electrically conductive-type impurity layer as a second well which are formed adjacent each other on a main surface of a first electrically conductive-type semiconductor substrate, said method comprising the steps of:

• forming by ion implantation a first electrically conductive-type buried layer with an impurity concentration profile and an impurity concentration density greater than that of the first electrically conductive-type substrate in a region thereof underlying the first and second electrically conductive-type impurity regions,
• patterning a resist which opens with a predetermined width at a position corresponding to the boundary region between the first and second electrically conductive-type impurity layers on the first electrically conductive-type semiconductor substrate, and
• forming by ion implantation a high concentration impurity layer in the boundary region between the first and second electrically conductive-type impurity layers and from said main surface of said substrate to said buried layer by using said resist,
• wherein said high concentration impurity layer is formed so that a peak of its impurity concentration profile occurs below the main surface of the semiconductor substrate, and wherein
• said step of forming the high concentration impurity layer includes the step of forming a second electrically conductive-type high concentration layer.

A method of producing a semiconductor device having a first electrically conductive-type impurity layer as a first well and a second electrically conductive-type impurity layer as a second well which are formed adjacent each other on a main surface of a first electrically conductive-type semiconductor substrate, said method comprising the steps of:

• forming by ion implantation a first electrically conductive-type buried layer with an impurity concentration profile and an impurity concentration density greater than that of the first electrically conductive-type substrate in a region thereof underlying the first and second electrically conductive-type impurity regions,
• patterning a resist which opens with a predetermined width at a position corresponding to the boundary region between the first and second electrically conductive-type impurity layers on the first electrically conductive-type semiconductor substrate, and
• forming by ion implantation a high concentration impurity layer in the boundary region between the first and second electrically conductive-type impurity layers and from said main surface of said substrate to said buried layer by using said resist,
• wherein said high concentration impurity layer is formed so that a peak of its impurity concentration profile occurs below the main surface of the semiconductor substrate, and wherein
• said step of forming the high concentration impurity layer includes the step of forming a first electrically conductive-type high concentration layer and wherein
• said step of forming the first electrically conductive-type high concentration impurity layer includes the step of forming a second electrically conductive-type high concentration impurity layer which is adjacent the first electrically conductive-type high concentration impurity layer.