Method of manufacturing a semiconductor device and semiconductor device obtained with such a method
The invention relates to a method of manufacturing a semiconductor device comprising a field effect transistor, in which method a semiconductor body of silicon with a substrate is provided at a surface thereof with a source region and a drain region of a first conductivity type which are situated above a buried isolation region and with a channel region, between the source and drain regions, of a second conductivity type, opposite to the first conductivity type, and with a gate region separated from the surface of the semiconductor body by a gate dielectric and situated above the channel region, wherein a mesa is formed in the semiconductor body in which the channel region is formed and wherein the source and drain regions are formed on both sides of the mesa in a semiconductor region that is formed using epitaxial growth, the source and drain regions thereby contacting the channel region.
1. Method of manufacturing a semiconductor device comprising a field effect transistor, in which method a semiconductor body of silicon with a substrate is provided at a surface thereof with a source region and a drain region of a first conductivity type which are situated above a buried isolation region and with a channel region, between the source and drain regions, of a second conductivity type, opposite to the first conductivity type, and with a gate region separated from the surface of the semiconductor body by a gate dielectric and situated above the channel region, and wherein a mesa is formed in the semiconductor body in which the channel region is formed and wherein the source and drain regions are formed on both side faces of the mesa with at least a predominate portion of the source and drain regions in a semiconductor region that is formed using epitaxial growth, the source and drain regions thereby contacting the channel and formed at least predominantly in material epitaxially grown, characterized in that the semiconductor region is formed contacting the mesa over substantially the whole thickness of the semiconductor region and is formed below the level of the gate dielectric.
2. Method according to claim 1 , characterized in that the source and drain regions are provided with extensions and are formed in the semiconductor region using two ion implantations alongside the mesa while during one of these ion implantations spacers are present on the side faces of the mesa.
3. The method according to claim 2 , wherein the ion implantation spacers are present for the first ion implantation of the source and drain regions, and the ion implantation spacers removed during second ion implantation, the second ion implantation including ion implantation of the source and drain regions as well as the extensions.
4. Method according to claim 1 , characterized in that the source and drain regions are provided with extensions and are formed in the semiconductor region using two ion implantations alongside the mesa while during one of these ion implantations spacers are present on the side faces of the mesa, wherein the extensions are provided with an interdigited comb like structure.
5. Method according to claim 4 , characterized in that the transistor is surrounded by a sunken isolation region extending into the semiconductor body to a greater depth than the buried isolation region.
6. Method according to claim 1 , characterized in that the buried isolation region is formed before the forming of the semiconductor region by an over-all deposition of an insulating layer followed by removal of a part of the insulating layer.
7. Method according to claim 1 , characterized in that at least parts of the side faces of the mesa are protected during processing by temporarily spacers.
8. Semiconductor device comprising a field effect transistor obtained by a method according to claim 1 .
9. The method of claim 1 , wherein the source and drain regions are provided with extensions formed by ion implantation of a portion of the mesa extending from the side face of the mesa toward the center of the mesa, leaving the channel region between the extensions.
10. The method of claim 1 , wherein the source and drain regions are provided with ion implantation resulting in a higher doping concentration than the doping concentration of extensions of the source and drain regions.
11. Method of manufacturing a semiconductor device comprising a field effect transistor, in which method a semiconductor body of silicon with a substrate is provided at a surface thereof with a source region and a drain region of a first conductivity type which are situated above a buried isolation region and with a channel region, between the source and drain regions, of a second conductivity type, opposite to the first conductivity type, and with a gate region separated from the surface of the semiconductor body by a gate dielectric and situated above the channel region, and wherein a mesa is formed in the semiconductor body in which the channel region is formed and wherein the source and drain regions are formed on both side faces of the mesa with at least a predominate portion of the source and drain regions in a semiconductor region that is formed using epitaxial growth, the source and drain regions thereby contacting the channel and formed at least predominantly in material epitaxially grown, characterized in that the semiconductor region is formed contacting the mesa over substantially the whole thickness of the semiconductor region and is formed below the level of the gate dielectric, wherein the buried isolation region is formed by formation of a further semiconductor region including a mixed crystal of silicon and germanium which after formation of the semiconductor region is removed by selective etching.