MOS transistor on SOI structure

1 . An electronic device, comprising:

a silicon layer having a first surface and a second surface,

an insulating layer in contact with the first surface of the silicon layer,

at least one transistor comprising source, drain, and body regions arranged in the silicon layer, and a gate region topping the body region and comprising a gate portion laterally extending beyond the source and drain regions, the body region being continued by a body contact region not covered with the gate region, and a region of extension of the body region being located under the gate portion;

the device further comprising, under the gate portion, a partial insulating trench in the silicon layer extending from the second face of said silicon layer down to a depth smaller than the thickness of said silicon layer, wherein the gate portion is less heavily-doped than the rest of the gate region.

2 . The device according to claim 1 , wherein the body contact region is laterally positioned next to the gate portion.

3 . The device according to claim 1 , wherein:

the body region comprises a channel region between the source region and the drain region; and

the gate region comprises a first portion topping the channel region, the gate portion being a second portion of the gate region continuing said first portion laterally above said channel region.

4 . The device according to claim 1 , wherein the partial insulating trench has a width greater than or equal to the width of the gate portion.

5 . The device according to claim 1 , wherein the ratio of the depth of the insulating trench to the thickness of the silicon layer is in the range from approximately 0.2 to 0.8.

6 . The device according to claim 1 , wherein the gate portion is coupled to at least one gate contact pad, for example, via a first silicide layer.

7 . The device according to claim 1 , wherein the body contact region is coupled to at least one body contact pad, for example, via a second silicide layer.

8 . The device according to claim 1 , wherein the body contact region, the source region, and the drain region are flush with the second surface of the silicon layer.

9 . The device according to claim 1 , wherein the body contact region is separate from the partial insulating trench.

10 . The device according to claim 1 , comprising a first peripheral insulating trench, the body contact region being laterally positioned between said first peripheral insulating trench and the partial insulating trench.

11 . The device according to claim 1 , comprising a second peripheral insulating trench, the source and drain regions being laterally positioned between said second peripheral insulating trench and the partial insulating trench.

12 . The device according to claim 1 , wherein the at least one transistor is a transistor on a structure of silicon-on-insulator type comprising the silicon layer, the insulating layer, and a substrate topped with said insulating layer, the structure being a structure of partially depleted silicon on insulator type.

13 . The device according to claim 1 , comprising a gate insulator layer between the gate region and the silicon layer.

14 . The device according to claim 13 , wherein the gate insulator layer has, under the gate portion, a thickness greater than the thickness of the rest of the gate insulator layer.

15 . A device, comprising:

a substrate;

a silicon layer on the substrate;

a source region in the silicon layer;

a drain region in the silicon layer;

a body region in the silicon layer and including an extension region and a body contact region in the silicon layer, the body contact region having a first surface spaced from the substrate by a first distance;

a trench in the silicon layer adjacent to the body contact region;

a gate region on the silicon layer and on the trench, the gate region having a second surface spaced from the substrate by a second distance, the second distance being greater than the first distance, the gate region including a gate portion laterally extending beyond the source and drain regions, body contact region not being covered with the gate region, and a region of extension of the body region being located under the gate portion, wherein the trench is under the gate portion and extends from the second face of said silicon layer down to a depth smaller than the thickness of said silicon layer, wherein the gate portion is less heavily-doped than the rest of the gate region.

16 . The device of claim 15 , wherein the gate region includes a sidewall that faces the body contact region.

17 . An electronic device, comprising:

a silicon layer including a first surface;

an insulating layer in contact with the first surface of the silicon layer;

a transistor, including:

a source region in the silicon layer;

a drain region in the silicon layer;

a body region in the silicon layer and including an extension region and a body contact region; and

a gate region including a gate portion laterally extending beyond the source and drain regions, wherein the body contact region is not covered by the gate region, wherein the extension region of the body region is under the gate region;

a trench under the gate region in the silicon layer extending partially through the silicon layer, wherein the gate portion is less heavily-doped than the rest of the gate region.

18 . The electronic device of claim 17 , comprising a first contact coupled to the body contact region and a second contact coupled to the gate region.