Method for manufacturing semiconductor device
View Patent ↗A manufacturing method for manufacturing a super-junction semiconductor device forms an oxide film and a nitride film on an n-type epitaxial layer exhibiting high resistance on an n-type semiconductor substrate exhibiting low resistance. The portion of the nitride film in the scribe region is left unremoved by patterning and an alignment marker is opened through the nitride film. After opening a trench pattern in the oxide film, trenches having a high aspect ratio are formed. The portion of the oxide film outside the scribe region is removed and a p-type epitaxial layer is buried in the trenches. The overgrown p-type epitaxial layer is polished with reference to the nitride film, the polished surface is finished by etching, and the n-type epitaxial layer surface is exposed.
1. A method for manufacturing a semiconductor device comprising:
(a) forming a lightly doped first epitaxial semiconductor layer of a first conductivity type on a first major surface of a heavily doped semiconductor substrate of the first conductivity type;
(b) forming a first mask film for forming a trench on the first major surface and forming a second mask film, comprising a material different from a material of the first mask film, subsequent to forming the first mask film for forming a super-junction structure in the first epitaxial semiconductor layer, the super-junction structure providing a main current path in an ON-state of the semiconductor device, the super-junction structure being depleted in an OFF-state of the semiconductor device, the super-junction structure comprising a columnar first region of the first conductivity type and a columnar second region of a second conductivity type extending in parallel to the main current path, the columnar first region and the columnar second region being arranged alternately and in adjacent to each other;
(c) selectively removing a portion of the second mask film in a marker region for mask positioning in a scribe region pattern and a portion of the second mask film in a region outside the scribe region pattern;
(d) forming an opening for forming a trench in the first mask film, the trench being necessary for shaping the second region with a column in adjacent to the first region and for arranging the second region and the first region alternately;
(e) forming the trench through the opening by etching using the first mask film for an etching mask, the trench having a high aspect ratio; and
(f) removing a portion of the first mask film outside a region covered with the second mask film and burying a second epitaxial semiconductor layer of the second conductivity type in the trench for forming the columnar second region and for further forming the super-junction structure.
2. The method according to claim 1 , wherein the first mask film comprises a silicon oxide film.
3. The method according to claim 1 , wherein the second mask film comprises a silicon nitride film.
4. The method according to claim 1 , wherein the trench having a high aspect ratio is formed through a Bosch process or by reactive ion etching using inductively coupled plasma.
5. The method according to claim 1 , wherein the trench having a high aspect ratio is formed by reactive ion etching using inductively coupled plasma.
6. The method according to claim 1 , wherein the second epitaxial semiconductor layer is buried in the trench such that the trench is filled with the second epitaxial semiconductor layer and, then, the second epitaxial semiconductor layer is chipped for exposing a surface of the first region.
7. The method according to claim 6 , wherein a torque variation of a polishing motor caused by a contact of a polishing pad to the second mask film is detected in exposing the surface of the first region for judging an end of a polishing treatment; and a surface portion of the second epitaxial semiconductor layer is etched for exposing the surface of the first region.