Method of making a bipolar transistor

Claim 1

A method for manufacturing a semiconductor device, comprising the steps of: (i) selectively forming in the surface of a semiconductor substrate an embedded layer of a conductivity type opposite to that of said substrate; (ii) covering said substrate having said embedded layer formed therein with an insulating layer containing an impurity at least in the superficial region thereof; (iii) removing by etching said insulating layer on said embedded layer to provide an opening portion through which at least part of said embedded layer is exposed; (iv) simultaneously forming by epitaxial growth a single-crystal semiconductor layer of the same conductivity type as that of said embedded layer on said embedded layer at said opening portion and a polycrystalline semiconductor layer on said insulating film; (v) diffusing by heating the impurity in said insulating layer into said polycrystalline semiconductor layer to provide said polycrystalline semiconductor layer with a conductivity type opposite to that of said single-crystal semiconductor layer; (vi) heat-treating in an O 2 -containing atmosphere the surface of said polycrystalline semiconductor layer and the surface of said single-crystal semiconductor layer to form on said surfaces a thermal oxide layer having a portion on said single-crystal semiconductor layer thinner than the portion on said polycrystalline semiconductor layer; (vii) etching said thermal oxide layer until the portion of said thermal oxide layer on said single-crystal semiconductor layer is etched off, leaving the thermal oxide layer on said polycrystalline semiconductor layer; and (viii) successively forming an internal base region and an emitter region in said single-crystal semiconductor layer by self-alignment using the remaining thermal oxide layer as a mask.

Claim 2

A method for manufacturing a semiconductor device, comprising the steps of: (i) selectively forming in the surface of a semiconductor substrate an embedded layer of a conductivity type opposite to that of said substrate; (ii) covering said substrate having said embedded layer formed therein with an insulating layer containing an impurity at least in the superficial region thereof; (iii) removing by etching said insulating layer on said embedded layer to provide an opening portion through which at least part of said embedded layer is exposed; (iv) simultaneously forming by epitaxial growth a single-crystal semiconductor layer of the same conductivity type as that of said embedded layer on said embedded layer at said opening portion and a polycrystalline semiconductor layer on said insulating film; (v) diffusing by heating the impurity in said insulating layer into said polycrystalline semiconductor layer to provide said polycrystalline semiconductor layer with a conductivity type opposite to that of said single-crystal semiconductor layer; (vi) heat-treating in an O 2 -containing atmosphere the surface of said polycrystalline semiconductor layer and the surface of said single-crystal semiconductor layer to form on said surfaces a thermal oxide layer having a portion on said single-crystal semiconductor layer thinner than the portion on said polycrystalline semiconductor layer; (vii) etching said thermal oxide layer until the portion of said thermal oxide layer on said single-crystal semiconductor layer is etched off, leaving the thermal oxide layer on said polycrystalline semiconductor layer; and (viii) successively forming an internal base region and an emitter region in said single-crystal semiconductor layer by self-alignment using the remaining thermal oxide layer as a mask.