Bipolar transistor and method for manufacturing the same

A method for manufacturing a bipolar transistor, the method comprising:

• etching a portion of a semiconductor substrate to form a trench, using an etching mask exposing a portion of the semiconductor substrate;
• forming a first epitaxial layer through an epitaxial process using first conduction type impurity ions to form a first collector and a second collector, wherein the second collector is formed into the semiconductor substrate;
• forming a first spacer on the inner wall of the first epitaxial layer;
• forming a second epitaxial layer to form a third collector, wherein the second epitaxial layer is formed over the first epitaxial layer and inside the first spacer, wherein the second epitaxial layer is formed through an epitaxial process over the first epitaxial layer exposed by the first spacer;
• forming an extrinsic base on the inner wall of the first spacer;
• forming an insulating film over the entire surface of the semiconductor substrate, in which the extrinsic base is formed;
• performing an ion implantation process using second conduction type impurity ions to form an intrinsic base in the second epitaxial layer, wherein in said forming the intrinsic base, after forming the insulating film, the second conduction type impurity ions are implanted in the surface of the second epitaxial layer through a blanket ion implantation process to form the intrinsic base;
• etching the insulating film to form a second spacer on the inner wall of the extrinsic base;
• and
• forming an emitter inside the second spacer.

A method for manufacturing a bipolar transistor, the method comprising:

• etching a portion of a semiconductor substrate to form a trench, using an etching mask exposing a portion of the semiconductor substrate;
• forming a first epitaxial layer through an epitaxial process using first conduction type impurity ions to form a first collector and a second collector, wherein the second collector is formed into the semiconductor substrate;
• forming a first spacer on the inner wall of the first epitaxial layer;
• forming a second epitaxial layer to form a third collector, wherein the second epitaxial layer is formed over the first epitaxial layer and inside the first spacer, wherein the second epitaxial layer is formed through an epitaxial process over the first epitaxial layer exposed by the first spacer;
• forming an extrinsic base on the inner wall of the first spacer;
• forming an insulating film over the entire surface of the semiconductor substrate, in which the extrinsic base is formed;
• performing an ion implantation process using second conduction type impurity ions to form an intrinsic base in the second epitaxial layer;
• etching the insulating film to form a second spacer on the inner wall of the extrinsic base;
• and
• forming an emitter inside the second spacer, wherein said forming the emitter includes:
• depositing first conduction type polysilicon to completely cover the etching mask,
• performing a CMP process such that the upper surface of the etching mask is exposed to planarize the first conduction type polysilicon,
• performing an oxidization process on a region exposed by the etching mask to form an oxide film, and
• removing the oxide film and the etching mask to form the emitter.