Method of producing a semiconductor device

Claim 1

A method of producing a semiconductor device comprising at least one bipolar transistor and an isolation region which are formed in an epitaxial layer formed on a semiconductor substrate having a buried layer, said method comprising, in sequence, the steps of: (A) forming a layer capable of masking against oxidation on said epitaxial layer, (B) forming an insulating layer on said anti-oxidation masking layer, (C) forming a patterned negative resist layer on said insulating layer, (D) selectively etching said insulating layer by using said negative resist layer as a mask, (E) introducing a first impurity into a first predetermined portion of said epitaxial layer corresponding to the isolation region by using a first patterned positive resist layer as a mask, (F) introducing a second impurity through said masking layer into a second predetermined portion of said epitaxial layer corresponding to a collector-connecting-region of the bipolar transistor by using a second patterned positive resist layer as a mask, (G) removing said positive resist mask, (H) forming a metal layer over the whole exposed surface, (I) removing said patterned negative resist layer and the portion of said metal layer thereon, (J) etching the remaining portion of the insulating layer and the portion of said anti-oxidation layer lying thereunder by using the remaining layer as a mask, (K) removing said remaining metal layer, (L) selectively thermal-oxidizing said epitaxial layer by using the remaining anti-oxidation masking layer as a pattern mask to form a thick oxide layer, while at the same time diffusing said introduced first and second impurities into said epitaxial layer to form said isolation region and said collector region in contact with said buried layer, respectively, and (M) forming a base region and an emitter region of the bipolar transistor in a portion of said epitaxial layer above said buried layer.

Claim 2

A method of producing a semiconductor device comprising at least one bipolar transistor and an isolation region which are formed in an epitaxial layer formed on a semiconductor substrate having a buried layer, said method comprising, in sequence, the steps of: (A) forming a layer capable of masking against oxidation on said epitaxial layer, (B) forming an insulating layer on said anti-oxidation masking layer, (C) forming a patterned negative resist layer on said insulating layer, (D) selectively etching said insulating layer by using said negative resist layer as a mask, (E) introducing a first impurity into a first predetermined portion of said epitaxial layer corresponding to the isolation region by using a first patterned positive resist layer as a mask, (F) introducing a second impurity through said masking layer into a second predetermined portion of said epitaxial layer corresponding to a collector-connecting-region of the bipolar transistor by using a second patterned positive resist layer as a mask, (G) removing said positive resist mask, (H) forming a metal layer over the whole exposed surface, (I) removing said patterned negative resist layer and the portion of said metal layer thereon, (J) etching the remaining portion of the insulating layer and the portion of said anti-oxidation layer lying thereunder by using the remaining layer as a mask, (K) removing said remaining metal layer, (L) selectively thermal-oxidizing said epitaxial layer by using the remaining anti-oxidation masking layer as a pattern mask to form a thick oxide layer, while at the same time diffusing said introduced first and second impurities into said epitaxial layer to form said isolation region and said collector region in contact with said buried layer, respectively, and (M) forming a base region and an emitter region of the bipolar transistor in a portion of said epitaxial layer above said buried layer.

Claim 7

A method of producing a semiconductor device comprising at least one bipolar transistor and an isolation region which are formed in an epitaxial layer formed on a semiconductor substrate having a buried layer, said method comprising, in sequence, the steps of: (A) forming a layer capable of masking against oxidation on said epitaxial layer, (B) forming an insulating layer on said anti-oxidation masking layer, (C) forming a patterned negative resist layer on said insulating layer, (D) introducing a first impurity into a first predetermined portion of said epitaxial layer corresponding to the isolation region by using a first patterned positive resist layer as a mask, (E) introducing a second impurity through said insulating and masking layers into a second predetermined portion of said epitaxial layer corresponding to a collector-connecting-region of the bipolar transistor by using a second patterned positive resist layer as a mask, (F) etching the portion of said insulating layer which is covered with said patterned negative resist layer by using a reaction between the water content of said negative resist layer and hydrogen fluoride gas, (G) removing said negative resist layer, (H) etching said anti-oxidation masking layer by using the remaining insulating layer as a mask, (I) removing said remaining insulating layer, (J) selectively thermally oxidizing said epitaxial layer to form a thick oxide layer, while at the same time diffusing said introduced first and second impurities into said epitaxial layer to form said isolation region and said collector-connecting-region in contact with said buried layer, respectively, and (K) forming a base region and an emitter region of the bipolar transistor in a portion of said epitaxial layer above said buried layer.

Claim 8

A method of producing a semiconductor device comprising at least one bipolar transistor and an isolation region which are formed in an epitaxial layer formed on a semiconductor substrate having a buried layer, said method comprising, in sequence, the steps of: (A) forming a layer capable of masking against oxidation on said epitaxial layer, (B) forming an insulating layer on said anti-oxidation masking layer, (C) forming a patterned negative resist layer on said insulating layer, (D) introducing a first impurity into a first predetermined portion of said epitaxial layer corresponding to the isolation region by using a first patterned positive resist layer as a mask, (E) introducing a second impurity through said insulating and masking layers into a second predetermined portion of said epitaxial layer corresponding to a collector-connecting-region of the bipolar transistor by using a second patterned positive resist layer as a mask, (F) etching the portion of said insulating layer which is covered with said patterned negative resist layer by using a reaction between the water content of said negative resist layer and hydrogen fluoride gas, (G) removing said negative resist layer, (H) etching said anti-oxidation masking layer by using the remaining insulating layer as a mask, (I) removing said remaining insulating layer, (J) selectively thermally oxidizing said epitaxial layer to form a thick oxide layer, while at the same time diffusing said introduced first and second impurities into said epitaxial layer to form said isolation region and said collector-connecting-region in contact with said buried layer, respectively, and (K) forming a base region and an emitter region of the bipolar transistor in a portion of said epitaxial layer above said buried layer.