Backside contact to final substrate
Device structures and fabrication methods for a backside contact to a final substrate An electrically-conducting connection is formed that extends through a device layer of a silicon-on-insulator substrate and partially through a buried insulator layer of the silicon-on-insulator substrate. After the electrically-conducting connection is formed, a handle wafer of the silicon-on-insulator substrate is removed. After the handle wafer is removed, the buried insulator layer is partially removed to expose the electrically-conducting connection. After the buried insulator layer is partially removed, a final substrate is coupled to the buried insulator layer such that the electrically-conducting connection is coupled with the final substrate.
1. A device structure formed using a silicon-on-insulator substrate, the device structure comprising:
a device layer of the silicon-on-insulator substrate;
a buried insulator layer of the silicon-on-insulator substrate, the buried insulator layer having a first surface in contact with the device layer and a second surface;
a substrate;
a trap-rich layer on the second surface of the buried insulator layer, the trap-rich layer between the substrate and the buried insulator layer; and
an electrically-conducting connection located in a trench extending from the device layer through the buried insulator lay to the trap-rich layer such that the electrically-conducting connection is coupled with the substrate, the electrically-conducting connection at least partially comprised of trap-rich material.
2. The device structure of claim 1 wherein the electrically-conducting connection is a contact plug comprised of a semiconductor material.
3. The device structure of claim 2 wherein the semiconductor material is polycrystalline silicon.
4. The device structure of claim 2 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.
5. The device structure of claim 4 wherein the dielectric material is comprised of silicon nitride or silicon dioxide.
6. The device structure of claim 1 wherein the electrically-conducting connection is fully comprised of the trap-rich material.
7. The device structure of claim 1 wherein the electrically-conducting connection comprises a portion of the trap-rich layer.