Vertical trench transistor

A method for fabricating the body regions or the body contact regions in a vertical trench transistor vertical trench transistor having a first electrode, a second electrode and a semiconductor body, the semiconductor including a plurality of transistor cells comprising source regions, body portion regions, at least one drift region and gate electrodes, each body portion region including a body region, the contact holes configured to contact the source and body regions, contact being made with the source regions and body regions using the first electrode, and the bottom of at least one contact hole adjoining at least one drift region, wherein the body portion regions are configured in such a way as to avoid excessive increases in electric fields at edges of the bottoms of the at least one contact hole, the method comprising:

• a) forming the contact holes in the semiconductor body, the contact holes having contact hole bottoms,
• b) covering the contact hole bottoms with a mask,
• c) producing the body region by applying dopants to uncovered inner walls of the contact holes.

A method for fabricating the body regions or the body contact regions in a vertical trench transistor, comprising the following steps of:

• forming contact holes in the semiconductor body between locations for trenches,
• producing body regions of the vertical trench transistor by applying dopants to all the inner walls of the contact holes,
• redoping portions of the body region which lie below bottoms of the contact holes, such that the semiconductor body that lies below the bottoms of the contact holes is redoped.

A method for fabricating the body regions or the body contact regions in a vertical trench transistor having a first electrode, a second electrode and a semiconductor body, the semiconductor including a plurality of transistor cells comprising source regions, body portion regions, at least one drift region and gate electrodes, each body portion region including a body region, the contact holes configured to contact the source and body regions, contact being made with the source regions and body regions using the first electrode, and the bottom of at least one contact hole adjoining at least one drift region, wherein the body portion regions are configured in such a way as to avoid excessive increases in electric fields at edges of the bottoms of the at least one contact hole, the method comprising:

• a) providing the contact holes in the semiconductor body;
• and
• b) implanting the body portion regions into side walls of the contact holes using oblique implantation.

A method for fabricating the body regions or the body contact regions in a A method for fabricating the body regions or the body contact regions in a vertical trench transistor vertical trench transistor having a first electrode, a second electrode and a semiconductor body, the semiconductor including a plurality of transistor cells comprising source regions, body portion regions, at least one drift region and gate electrodes, each body portion region including a body region, the contact holes configured to contact the source and body regions, contact being made with the source regions and body regions using the first electrode, and the bottom of at least one contact hole adjoining at least one drift region, wherein the body portion regions are configured in such a way as to avoid excessive increases in electric fields at edges of the bottoms of the at least one contact hole, the method comprising:

• forming the body regions in the semiconductor body,
• forming contact holes in the semiconductor body such that the body regions are penetrated by the contact holes,
• applying corresponding dopants to uncovered inner walls of the contact holes such that the body regions are extended to regions which extend around edges of bottoms of the contact hole.