Semiconductor device with intrinsic base diffusion layer, extrinsic base diffusion layer, and common base diffusion

A bipolar structure semiconductor device, comprising:

• an intrinsic base diffusion layer formed on the substantially central portion of a semiconductor region surrounded by a separating insulation film on the major surface of a semiconductor substrate;
• an external base diffusion layer overlapping with the outer circumference of said intrinsic base diffusion layer, surrounding said intrinsic base diffusion layer, and reaching the separating insulation film;
• and
• a common base diffusion layer formed in the semiconductor region, overlapping with said intrinsic base diffusion layer, overlapping with at least the inner circumference of said external base diffusion layer, and formed in a depth deeper than the depth of said external base diffusion layer, but not exceeding the depth of said intrinsic base diffusion layer;
• wherein said common base diffusion layer is formed so as to overlap with said intrinsic base diffusion layer and said external base diffusion layer, and to reach the separating insulation film;
• and
• an impurity concentration of said external base diffusion layer is higher than an impurity concentration of said intrinsic base diffusion layer, and an impurity concentration of said common base diffusion layer is lower than an impurity concentration of said intrinsic base diffusion layer.

A semiconductor device, comprising:

• an intrinsic base diffusion layer of a second conductivity type formed on the substantially central portion of a semiconductor region of a first conductivity type surrounded by a separating insulation film on the major surface of a semiconductor substrate;
• an external base diffusion layer of a second conductivity type overlapping with the outer circumference of said intrinsic base diffusion layer, surrounding said intrinsic base diffusion layer, and reaching the separating insulation film;
• and
• a common base diffusion layer of a second conductivity type formed in the semiconductor region, overlapping with said intrinsic base diffusion layer, the outer circumference thereof overlapping with the inner circumference of said external base diffusion layer, and formed in a depth deeper than the depth of said external base diffusion layer, but not exceeding the depth of said intrinsic base diffusion layer.

A semiconductor device, comprising:

• an intrinsic base diffusion layer of a second conductivity type formed on the substantially central portion of a semiconductor region of a first conductivity type surrounded by a separating insulation film on the major surface of a semiconductor substrate;
• an external base diffusion layer of a second conductivity type overlapping with the outer circumference of said intrinsic base diffusion layer, surrounding said intrinsic base diffusion layer, and reaching the separating insulation film;
• and
• a common base diffusion layer of a second conductivity type formed in the semiconductor region, overlapping with said intrinsic base diffusion layer, overlapping with at least the inner circumference of said external base diffusion layer, and formed in a depth deeper than the depth of said external base diffusion layer, but not exceeding the depth of said intrinsic base diffusion layer;
• wherein said common base diffusion layer is formed so as to overlap with said intrinsic base diffusion layer and said external base diffusion layer, and to reach the separating insulation film;
• and
• an impurity concentration of said external base diffusion layer is higher than an impurity concentration of said intrinsic base diffusion layer, and an impurity concentration of said common base diffusion layer is lower than an impurity concentration of said intrinsic base diffusion layer.