Semiconductor-on-insulator with back side connection
View Patent ↗Embodiments of the present invention provide for the removal of excess carriers from the body of active devices in semiconductor-on-insulator (SOI) structures. In one embodiment, a method of fabricating an integrated circuit is disclosed. In one step, an active device is formed in an active layer of a semiconductor-on-insulator wafer. In another step, substrate material is removed from a substrate layer disposed on a back side of the SOI wafer. In another step, an insulator material is removed from a back side of the SOI wafer to form an excavated insulator region. In another step, a conductive layer is deposited on the excavated insulator region. Depositing the conductive layer puts it in physical contact with a body of an active device in a first portion of the excavated insulator region. The conductive layer then couples the body to a contact in a second detached portion of the excavated insulator region.
1. A semiconductor-on-insulator structure comprising:
an electrically conductive layer;
an insulator layer being located above said electrically conductive layer, and partially vertically coextensive with said electrically conductive layer in an excavated insulator region;
an active layer being located above said insulator layer, and comprising an active device with a body;
a body contact physically connecting said electrically conductive layer and said body, being located in a first portion of said excavated insulator region;
wherein said electrically conductive layer couples said body contact to a contact in said active layer, said contact being located in a second portion of said excavated insulator region, said second portion being detached from said first portion;
a circuit branch comprising said body contact and said contact; and
wherein said circuit branch connects a gate of said active device to said body of said active device.
2. The semiconductor-on-insulator structure of claim 1 , further comprising:
a variable impedance circuit branch comprising said body contact and said contact;
wherein said variable impedance circuit branch is configured to have a high impedance when said active device is in an on state, and said variable impedance circuit branch is configured to have a low impedance when said active device is not in said on state.
3. The semiconductor-on-insulator structure of claim 2 , said variable impedance circuit branch further comprising:
a gate region of said active device;
wherein said variable impedance circuit branch latches said body to said gate voltage when said active device is in an off state.
4. The semiconductor-on-insulator structure of claim 3 , wherein said body contact is a hot-carrier diode junction.
5. The semiconductor-on-insulator structure of claim 4 , further comprising a handle wafer above said active layer.
6. The semiconductor-on-insulator structure of claim 5 , further comprising:
a landing pad formed above said body contact;
wherein said landing pad is comprised of a wider region of said body.
7. A semiconductor-on-insulator structure comprising:
an electrically conductive layer;
an insulator layer being located above said electrically conductive layer, and partially vertically coextensive with said electrically conductive layer in an excavated insulator region;
an active layer being located above said insulator layer, and comprising an active device with a body;
a body contact physically connecting said electrically conductive layer and said body, being located in a first portion of said excavated insulator region;
wherein said electrically conductive layer couples said body contact to a contact in said active layer, said contact being located in a second portion of said excavated insulator region, said second portion being detached from said first portion;
wherein said body contact is ohmic;
wherein said contact is directly below a diode formed in said active layer; and
wherein said diode is reversed biased when said active device is in an on state.
8. The semiconductor-on-insulator structure of claim 7 , further comprising:
a circuit branch comprising said body contact and said contact;
wherein said circuit branch connects a source of said active device to said body of said active device.
9. The semiconductor-on-insulator structure of claim 7 , further comprising:
a variable impedance circuit branch comprising said body contact and said contact;
wherein said variable impedance circuit branch is configured to have a high impedance when said active device is in an on state, and said variable impedance circuit branch is configured to have a low impedance when said active device is not in said on state.
10. The semiconductor-on-insulator structure of claim 9 , said variable impedance circuit branch further comprising:
a gate region of said active device;
wherein said variable impedance circuit branch latches said body to said gate voltage when said active device is in an off state.
11. The semiconductor-on-insulator structure of claim 10 , wherein said body contact is a hot-carrier diode junction.
12. The semiconductor-on-insulator structure of claim 11 , further comprising a handle wafer above said active layer.
13. The semiconductor-on-insulator structure of claim 12 , further comprising:
a landing pad formed above said body contact;
wherein said landing pad is comprised of a wider region of said body.
14. A semiconductor-on-insulator structure comprising:
an electrically conductive layer;
an insulator layer being located above said electrically conductive layer, and partially vertically coextensive with said electrically conductive layer in an excavated insulator region;
an active layer being located above said insulator layer, and comprising an active device with a body;
a body contact physically connecting said electrically conductive layer and said body, being located in a first portion of said excavated insulator region;
wherein said electrically conductive layer couples said body contact to a contact in said active layer, said contact being located in a second portion of said excavated insulator region, said second portion being detached from said first portion; and
a landing pad formed above said body contact;
wherein said landing pad is comprised of a wider region of said body.
15. The semiconductor-on-insulator structure of claim 14 , further comprising:
a circuit branch comprising said body contact and said contact;
wherein said circuit branch connects a source of said active device to said body of said active device.
16. The semiconductor-on-insulator structure of claim 14 , further comprising:
a variable impedance circuit branch comprising said body contact and said contact;
wherein said variable impedance circuit branch is configured to have a high impedance when said active device is in an on state, and said variable impedance circuit branch is configured to have a low impedance when said active device is not in said on state.
17. The semiconductor-on-insulator structure of claim 16 , said variable impedance circuit branch further comprising:
a gate region of said active device;
wherein said variable impedance circuit branch latches said body to said gate voltage when said active device is in an off state.
18. The semiconductor-on-insulator structure of claim 17 , wherein said body contact is a hot-carrier diode junction.
19. The semiconductor-on-insulator structure of claim 18 , further comprising a handle wafer above said active layer.
20. A semiconductor-on-insulator structure comprising:
an electrically conductive layer;
an insulator layer being at least partially vertically coextensive with said electrically conductive layer in an excavated insulator region;
an active layer being located above said insulator layer, and comprising an active device with a body; and
a body contact physically connecting said electrically conductive layer and said body;
wherein said electrically conductive layer couples said body contact to a contact in said active layer;
a circuit branch comprising said body contact and said contact; and
wherein said circuit branch connects a gate of said active device to said body of said active device.
21. The semiconductor-on-insulator structure of claim 20 , wherein:
said body contact is ohmic;
said contact is directly below a diode formed in said active layer; and
said diode is reversed biased when said active device is in an on state.