Backside contact to a final substrate

1. A device structure including a backside contact comprising:

a silicon-on-insulator substrate including:

a device layer including at least one switch;

a dielectric layer disposed above and coupled to the device layer;

a buried insulator layer, wherein the at least one switch is disposed between the buried insulator layer and the dielectric layer; and

a trench including an electrically-conducting connection, wherein the trench extends through the device layer and partially through the buried insulator layer, and the electrically-conducting connection is exposed by a removed portion of the buried insulator layer; and

a final substrate coupled to the buried insulator layer such that the electrically-conducting connection contacts the final substrate.

2. The device structure of claim 1 , wherein the backside contact comprises the electrically-conducting connection.

3. The device structure of claim 1 , wherein the trench is filled with a semiconductor material.

4. The device structure of claim 3 , wherein the trench is lined with an etch stop layer comprised of a material that etches selective to the semiconductor material.

5. The device structure of claim 2 , wherein:

the buried insulator layer includes a first surface in direct contact with the device layer and a second surface in direct contact with a removable handle wafer, and the trench has a bottom surface that terminates within the buried insulator layer between the first surface and the second surface when the electrically-conducting connection is formed; and

the bottom surface of the trench is exposed at the second surface of the buried insulator layer.

6. The device structure of claim 5 , wherein a surface of the final substrate is attached to the second surface of the buried insulator layer to place the electrically-conducting connection in contact with the final substrate.

7. The device structure of claim 6 , wherein the electrically-conducting connection is a contact plug positioned in the trench.

8. The device structure of claim 7 , wherein the second surface of the buried insulator layer includes a deposited trap-rich layer.

9. The device structure of claim 7 , wherein the surface of the final substrate is attached to the second surface of the buried insulator layer with an adhesive layer.

10. The device structure of claim 1 , wherein the buried insulator layer includes a first surface in direct contact with the device layer and a second surface exposed after a handle wafer is removed, and before the final substrate is coupled to the second surface of the buried insulator layer, a trap-rich layer is deposited on the second surface of the buried insulator layer.

11. The device of claim 10 , wherein the electrically-conducting connection is a contact plug positioned in the trench.

12. A device structure with a backside contact comprising:

a silicon-on-insulator substrate including a device layer, and a buried insulator layer;

a dielectric layer disposed above and coupled to the device layer;

at least one switch disposed in the device layer between the buried insulator layer and the dielectric layer;

a trench including an electrically-conducting connection, wherein the electrically-conducting connection is exposed by a removed portion of the buried insulator layer, and the trench extends through the device layer and partially through the buried insulator layer; and

a final substrate is coupled to the buried insulator layer such that the electrically-conducting connection contacts the final substrate.

13. The device structure of claim 12 , wherein the backside contact comprises the electrically-conducting connection.

14. The device structure of claim 13 , wherein the trench is filled with a semiconductor material.

15. The device structure of claim 14 , wherein the trench is lined with an etch stop layer comprised of a material that etches selective to the semiconductor material.

16. The device structure of claim 13 , wherein the buried insulator layer includes a first surface in direct contact with the device layer and a second surface in direct contact with a removable handle wafer, and the trench has a bottom surface that terminates within the buried insulator layer between the first surface and the second surface when the electrically-conducting connection is formed.

17. The device structure of claim 14 , wherein the semiconductor material is polycrystalline silicon, and the electrically-conducting connection is a contact plug positioned in the trench.

18. The device structure of claim 17 , wherein the trench includes a bottom surface and an etch stop at the bottom surface, the etch stop comprised of a dielectric material that etches selective to the semiconductor material of the contact plug.

19. The device structure of claim 18 , wherein the dielectric material is comprised of silicon nitride or silicon dioxide, and the electrically-conducting connection is comprised of trap-rich material.