Method of manufacturing a lateral bipolar transistor

Claim 1

A bipolar transistor characterized by comprising: a semiconductor substrate (101, 102); first and second polycrystalline semiconductor layers (105₁, 105₂) formed on the semiconductor sub­strate, the first and second layers being separated from each other and used as an emitter-leading electrode and a collector-leading electrode, respectively; a third polycrystalline semiconductor layer (118) formed on the semiconductor substrate and located between the first and second polycrystalline semiconduc­tor layers, with an insulation film (112) interposed; a first impurity-diffusion layer (115), of a first conductivity type, which is formed in the semiconductor substrate and is in contact with the first polycrys­talline semiconductor layer; a second impurity-diffusion layer (116), of a second conductivity type, which is formed in the semi­conductor substrate and is in contact with the first impurity-diffusion layer; a third impurity-diffusion layer (119), of the second conductivity type, which is formed in the semi­conductor device and is in contact with both the third polycrystalline semiconductor layer and the second impurity-diffusion layer; a fourth impurity-diffusion layer (117), of the first conductivity type, which is formed in the semicon­ductor substrate and is in contact with both the third impurity-diffusion layer and the second impurity-­diffusion layer; and a fifth impurity-diffusion layer (114), of the first conductivity type, which is in contact with both the second polycrystalline semiconductor layer and the fourth impurity-diffusion layer.

Claim 3

A method for manufacturing a bipolar transistor, characterized by comprising the steps of: forming a first insulation film (104′) on a semi­conductor substrate (101, 102); exposing a predetermined surface portion of the semiconductor substrate by selectively removing the first insulation film; forming a first crystalline semiconductor layer (105) on the resultant semiconductor structure; forming a first photoresist film (106) having a predetermined pattern on the first polycrystalline semi­conductor layer; ion-implanting first impurities (107, 107′), which are of a first conductivity type, into the first polycrystalline semiconductor layer, using the first photoresist film as a mask; removing the first photoresist film; ion-implanting second impurities (108, 108′), which are of a second conductivity type and have a larger dif­fusion coefficient than that of the first impurities, into the first crystalline semiconductor layer through the entire surface thereof; forming a second insulation film (111) on the first polycrystalline semiconductor layer; forming a second photoresist film (109) having a predetermined pattern on the second insulation film; forming an opening to expose a predetermined sur­face portion of the semiconductor substrate by selec­tively removing the second insulation film and the first polycrystalline semiconductor layer, using the second photoresist film as a mask, such that the first poly­crystalline semiconductor layer is divided into: a second polycrystalline semiconductor layer (105₁) con­taining both impurities of the first conductivity type and impurities of the second conductivity type; and a third polycrystalline semiconductor layer (105₂) con­taining only impurities of the second conductivity type; removing the second photoresist films; forming a third insulation film (112) on the resul­tant semiconductor structure; exposing the predetermined surface portion of the semiconductor substrate once again, by selectively removing the third insulation film such that the third insulation film remains on side walls of the opening; heat-treating the resultant semiconductor struc­ture, so as both to form a fourth insulation film (113) on the exposed surface portion of the semiconductor sub­strate and to activate the first and second impurities such that the semiconductor substrate (101, 102) con­tains: a first impurity-diffusion layer (115) which is of the second conductivity type; a second impurity-­diffusion layer (116) which is of the first conductivity and is in contact with the first impurity-diffusion layer; and a third impurity-diffusion layer (114) of the second conductivity; ion-implanting third impurities of the first con­ductivity type into the fourth insulation film; forming a fourth impurity-diffusion layer (117), which is of the first conductivity type and is in con­tact with both the second and third impurity-diffusion layers, by activating the third impurities implanted into the fourth insulation film; exposing the predetermined surface portion of the semiconductor substrate once again, by removing the fourth insulation film; forming a fourth polycrystalline semiconductor layer (118), which contains fourth impurities of the second conductivity, on the entire surface of the resul­tant semiconductor structure; and forming a fifth impurity-diffusion layer (119), which is of the first conductivity type, is located inside the fourth impurity-diffusion layer, and is con­tact with the second impurity-diffusion layer, by acti­vating the fourth impurities to diffuse from the fourth polycrystalline semiconductor layer into the fourth impurity-diffusion layer.

Claim 4

A method for manufacturing a bipolar transistor, characterized by comprising the steps of: forming a first insulation film (104′) on a semi­conductor substrate (101, 102); exposing a predetermined surface portion of the semiconductor substrate by selectively removing the first insulation film; forming a first crystalline semiconductor layer (105) on the resultant semiconductor structure; forming a first photoresist film (106) having a predetermined pattern on the first polycrystalline semi­conductor layer; ion-implanting first impurities (107, 107′), which are of a first conductivity type, into the first polycrystalline semiconductor layer, using the first photoresist film as a mask; removing the first photoresist film; ion-implanting second impurities (108, 108′), which are of a second conductivity type and have a larger dif­fusion coefficient than that of the first impurities, into the first crystalline semiconductor layer through the entire surface thereof; forming a second insulation film (111) on the first polycrystalline semiconductor layer; forming a second photoresist film (109) having a predetermined pattern on the second insulation film; forming an opening to expose a predetermined sur­face portion of the semiconductor substrate by selec­tively removing the second insulation film and the first polycrystalline semiconductor layer, using the second photoresist film as a mask, such that the first poly­crystalline semiconductor layer is divided into: a second polycrystalline semiconductor layer (105₁) con­taining both impurities of the first conductivity type and impurities of the second conductivity type; and a third polycrystalline semiconductor layer (105₂) con­taining only impurities of the second conductivity type; removing the second photoresist films; forming a third insulation film (112) on the resul­tant semiconductor structure; exposing the predetermined surface portion of the semiconductor substrate once again, by selectively removing the third insulation film such that the third insulation film remains on side walls of the opening; heat-treating the resultant semiconductor struc­ture, so as both to form a fourth insulation film (113) on the exposed surface portion of the semiconductor sub­strate and to activate the first and second impurities such that the semiconductor substrate (101, 102) con­tains: a first impurity-diffusion layer (115) which is of the second conductivity type; a second impurity-­diffusion layer (116) which is of the first conductivity and is in contact with the first impurity-diffusion layer; and a third impurity-diffusion layer (114) of the second conductivity; ion-implanting third impurities of the first con­ductivity type into the fourth insulation film; forming a fourth impurity-diffusion layer (117), which is of the first conductivity type and is in con­tact with both the second and third impurity-diffusion layers, by activating the third impurities implanted into the fourth insulation film; exposing the predetermined surface portion of the semiconductor substrate once again, by removing the fourth insulation film; forming a fourth polycrystalline semiconductor layer (118), which contains fourth impurities of the second conductivity, on the entire surface of the resul­tant semiconductor structure; and forming a fifth impurity-diffusion layer (119), which is of the first conductivity type, is located inside the fourth impurity-diffusion layer, and is con­tact with the second impurity-diffusion layer, by acti­vating the fourth impurities to diffuse from the fourth polycrystalline semiconductor layer into the fourth impurity-diffusion layer.