Buried source-drain contact for integrated circuit transistor devices and method of making same
An integrated circuit transistor is formed on a substrate. A trench in the substrate is at least partially filed with a metal material to form a source (or drain) contact buried in the substrate. The substrate further includes a source (or drain) region in the substrate which is in electrical connection with the source (or drain) contact. The substrate further includes a channel region adjacent to the source (or drain) region. A gate dielectric is provided on top of the channel region and a gate electrode is provided on top of the gate dielectric. The substrate may be of the silicon on insulator (SOI) or bulk type. The buried source (or drain) contact makes electrical connection to a side of the source (or drain) region using a junction provided at a same level of the substrate as the source (or drain) and channel regions.
1. An integrated circuit transistor, comprising:
a substrate including a semiconductor region and a trench having side walls and a bottom;
a metal material at least partially filling the trench and insulated from the semiconductor region along the side walls and bottom of the trench to form a source contact buried in the substrate;
a source region in the substrate in electrical connection with a top surface of the metal material for the source contact;
a channel region in the substrate adjacent the source region;
a gate dielectric on top of the channel region; and
a gate electrode on top of the gate dielectric.
2. The transistor of claim 1 , wherein the substrate comprises a silicon on insulator (SOI) substrate including an insulator layer between a base substrate layer and a semiconductor layer, wherein the source region and channel region are located in the semiconductor layer, and wherein the trench extends into the insulator layer with the insulating layer insulating the sidewalls and bottom of the trench.
3. The transistor of claim 2 , wherein the semiconductor layer of the substrate includes plurality of fins, each fin including said source region and channel region.
4. The transistor of claim 2 , further comprising a conductive junction provided at a same level as the semiconductor layer to electrically connect the top surface of the metal material for the buried source contact with a side of the source region.
5. The transistor of claim 4 , further comprising a silicide region between the top surface of the metal material for the buried source contact and a bottom of the conductive junction.
6. The transistor of claim 1 , wherein the substrate comprises a bulk substrate including first semiconductor layer between a base substrate layer and a second semiconductor layer, wherein the source region and channel region are located in the second semiconductor layer, and wherein the trench extends into the first semiconductor layer.
7. The transistor of claim 6 , wherein the second semiconductor layer of the substrate includes plurality of fins, each fin including said source region and channel region.
8. The transistor of claim 6 , wherein the trench includes an insulating layer insulating the metal material of the source contact at the side walls and bottom of the trench from the first semiconductor layer.
9. The transistor of claim 6 , further comprising a conductive junction provided at a same level as the second semiconductor layer to electrically connect the top surface of the metal material for the buried source contact with a side of the source region.
10. The transistor of claim 9 , further comprising a silicide region between the top surface of the metal material for the buried source contact and a bottom of the conductive junction.
11. The transistor of claim 1 , wherein the substrate comprises a bulk substrate of semiconductor material, wherein the source region and channel region are located in a top portion of the bulk substrate, and wherein the trench extends into the bulk substrate to a depth below the top portion.
12. The transistor of claim 11 , wherein the top portion of the bulk substrate includes plurality of fins, each fin including said source region and channel region.
13. The transistor of claim 11 , wherein the trench includes an insulating layer insulating the metal material of the source contact at the side walls and bottom of the trench from the bulk substrate.
14. The transistor of claim 11 , further comprising a conductive junction provided at a same level as the top portion to electrically connect the top surface of the metal material for the buried source contact with a side of the source region.
15. The transistor of claim 14 , further comprising a silicide region between the top surface of the metal material for the buried source contact and a bottom of the conductive junction.
16. The transistor of claim 1 , further comprising a gate contact extending from above the gate electrode to make electrical contact with the gate electrode, said gate contact laterally extending over the source region.
17. The transistor of claim 16 , further comprising:
a premetal dielectric region over the substrate within which the gate contact is located; and
a via extending through said premetal dielectric region to make electrical contact with said buried source contact.
18. The transistor of claim 1 , further comprising a fin including said source region and channel region.
19. The transistor of claim 1 , further comprising a conductive junction provided to electrically connect the top surface of the metal material for the buried source contact with a side of the source region.
20. The transistor of claim 19 , further comprising a silicide region between the top surface of the metal material for the buried source contact and a bottom of the conductive junction.
21. The transistor of claim 1 , further comprising an insulating layer of material separating the metal material of the source contact from semiconductor region of the substrate.
22. The transistor of claim 1 , wherein the source region and channel region are located in a top portion of the substrate, and wherein the trench extends into the substrate to a depth below a bottom of the source region and channel region.
23. The transistor of claim 22 , further comprising a conductive junction provided at a same level as the source region to electrically connect the top surface of the metal material for the buried source contact with a side of the source region.
24. The transistor of claim 23 , further comprising a silicide region between the top surface of the metal material for the buried source contact and a bottom of the conductive junction.
25. An integrated circuit transistor, comprising:
a region of semiconductor material including a source region, a drain region and a channel region between the source region and drain region;
an insulating layer supporting said region of semiconductor material, said insulating layer including a trench extending to a depth below a bottom of said source region;
a metal material at least partially filling the trench to form a source contact buried in said insulating layer, said source contact having sidewalls and a bottom insulated by said insulating layer;
a conductive junction positioned to electrically connect a top of the buried source contact with the source region;
a gate dielectric on top of the channel region; and
a gate electrode on top of the gate dielectric.
26. The transistor of claim 25 , wherein the region of semiconductor material is an upper semiconductor layer of a silicon on insulator (SOI) substrate.
27. The transistor of claim 25 , further comprising a silicide region between the top of the buried source contact and a bottom of the conductive junction.
28. The transistor of claim 25 , wherein the source region, drain region and channel region are defined in a fin.
29. The transistor of claim 25 , further comprising a gate contact extending from above the gate electrode to make electrical contact with the gate electrode.
30. The transistor of claim 29 , further comprising:
a premetal dielectric region within which the gate contact is located; and
a via extending through said premetal dielectric region to make electrical contact with said buried source contact.
31. An integrated circuit transistor, comprising:
a region of semiconductor material including a source region and a channel region adjacent the source region;
a substrate layer supporting said region of semiconductor material, said substrate layer including a trench extending into and terminating within said substrate layer to a depth below a bottom of said source region;
a metal material at least partially filling the trench to form a buried source contact;
a conductive junction positioned at a same level as the source regions to electrically connect a top of the buried source contact with a side of said source region; and
a gate dielectric on top of the channel region; and a gate electrode on top of the gate dielectric.
32. The transistor of claim 31 , further comprising a silicide region between the top of the buried source contact and a bottom of the conductive junction.
33. The transistor of claim 31 , wherein the source region and channel region are defined in a fin.
34. The transistor of claim 31 , further comprising: a premetal dielectric region; and
a via extending through said premetal dielectric region to make electrical contact with said buried source contact.
35. The transistor of claim 31 , wherein the region of semiconductor material is an upper semiconductor layer of a silicon on insulator (SOI) substrate.
36. The transistor of claim 31 , further comprising an insulating material separating the metal material of the source contact from a conductive portion of the substrate layer.