Method of forming a semiconductor device and structure therefor
An embodiment of a semiconductor device includes forming an active region that extends vertically into the semiconductor material in which the semiconductor device is formed. The active region may include a P-N junction or alternately a gate or a channel region of an MOS transistor.
1. A method of forming a semiconductor device comprising:
providing a semiconductor substrate;
forming a semiconductor region of a first conductivity type on a surface of the semiconductor substrate, the semiconductor region having a major surface;
forming a first opening extending from the major surface a first distance into the semiconductor region;
forming a second opening extending from the major surface substantially the first distance into the semiconductor region;
forming a first semiconductor material in the first opening, the first semiconductor material having a second conductivity type that is opposite to the conductivity type of the first conductivity type, the first semiconductor material forming a first P-N junction with the semiconductor region, the first semiconductor material forming a drain of a transistor;
forming a doped semiconductor region in the second opening, the doped semiconductor region having the second conductivity type, the doped semiconductor region forming a second P-N junction with an adjacent semiconductor material, the doped semiconductor region forming a source of the transistor; and
forming a third opening extending from the major surface substantially the first distance into the semiconductor region, and forming an insulator along at least a portion of sidewalls of the third opening, wherein a portion of the third opening remains as a fourth opening within the insulator, and forming a second semiconductor material in the fourth opening wherein the insulator is between the second semiconductor material and sidewalls of the third opening.
2. The method of claim 1 including forming the insulator between the second semiconductor material and the semiconductor region.
3. The method of claim 1 wherein forming the doped semiconductor region includes forming a second semiconductor material on sidewalls of the second opening and forming a third semiconductor material on sidewalls of the second semiconductor material.
4. The method of claim 1 wherein forming the doped semiconductor region includes doping sidewalls of the second opening to have the first conductivity type, and forming a second semiconductor material on the doped sidewalls.
5. The method of claim 1 wherein the third opening is positioned laterally across the major surface between the first and second openings.
6. The method of claim 1 including forming a portion of a third semiconductor region to extend laterally along a plane of the major surface through the doped semiconductor region and into the adjacent semiconductor material, the third semiconductor region extending from the major surface into the semiconductor region.
7. The method of claim 1 further including forming a third opening extending from the major surface substantially the first distance into the semiconductor region, and forming a first insulator along at least a portion of sidewalls of the third opening, the first insulator forming a fourth opening, and forming a second semiconductor material in a first portion of the fourth opening wherein the first insulator is between the second semiconductor material and sidewalls of the third opening, forming a third semiconductor material in a second portion of the fourth opening, and forming a second insulator separating the second and third semiconductor materials.
8. The method of claim 7 wherein forming the third semiconductor material includes forming a fifth opening in the second semiconductor material, forming the second insulator within a portion of the fifth opening thereby forming a sixth opening in the second insulator, and forming the third semiconductor material in the sixth opening.