Passive devices over polycrystalline semiconductor fins
Structures including a passive device and methods of forming such structures. Multiple fins are positioned on a substrate, and an interconnect structure is positioned over the substrate. The fins contain a polycrystalline semiconductor material, and the interconnect structure includes a passive device that is positioned over the fins. The passive device may be, for example, an inductor or a transmission line.
1. A method comprising:
forming a first plurality of fins comprised of a first polycrystalline semiconductor material on a substrate, wherein the substrate includes a top surface and a region beneath the top surface, the region is comprised of a second polycrystalline semiconductor material, the first plurality of fins have a height relative to the top surface of the substrate, the first plurality of fins contain the first polycrystalline semiconductor material over an entirety of the height, and the first plurality of fins are positioned over the region;
forming a gate structure having an overlapping relationship with the first plurality of fins; and
forming an interconnect structure over the substrate,
wherein the interconnect structure includes a passive device that is positioned over the first plurality of fins, and the gate structure is not contacted by the interconnect structure.
2. The method of claim 1 wherein the second polycrystalline semiconductor material of the region is concurrently formed with the first polycrystalline semiconductor material of the first plurality of fins.
3. The method of claim 1 wherein the first polycrystalline semiconductor material of the first plurality of fins has an electrical resistivity that is in a range of 1,000 ohm-cm to 10,000 ohm-cm.
4. The method of claim 1 wherein forming the first plurality of fins comprised of the first polycrystalline semiconductor material on the substrate comprises:
implanting the first plurality of fins with ions of an inert gas species to cause crystalline damage; and
annealing the first plurality of fins to repair the crystalline damage and form the first polycrystalline semiconductor material.
5. The method of claim 4 wherein the first plurality of fins are located in a first device region, a second plurality of fins are located in a second device region, and further comprising:
masking the second plurality of fins with an implantation mask when the first plurality of fins are implanted.
6. The method of claim 1 further comprising:
epitaxially growing a section of a semiconductor layer on each of the first plurality of fins.
7. The method of claim 6 wherein the semiconductor layer comprises a third polycrystalline semiconductor material.
8. A structure comprising:
a substrate including a top surface and a first region beneath the top surface, the first region comprised of a first polycrystalline semiconductor material;
a plurality of fins on the substrate, the plurality of fins comprised of a second polycrystalline semiconductor material, the plurality of fins having a height relative to the top surface of the substrate, the plurality of fins containing the second polycrystalline semiconductor material over an entirety of the height, and the plurality of fins positioned over the first region;
an interconnect structure over the substrate, the interconnect structure including a passive device that is positioned over the plurality of fins; and
a gate structure having an overlapping relationship with the plurality of fins,
wherein the gate structure is not contacted by the interconnect structure.
9. The structure of claim 8 wherein the second polycrystalline semiconductor material of the plurality of fins and the first polycrystalline semiconductor material of the first region each have an electrical resistivity that is in a range of about 1,000 ohm-cm to about 10,000 ohm-cm.
10. The structure of claim 8 wherein the second polycrystalline semiconductor material of the plurality of fins and the first polycrystalline semiconductor material of the first region each have an electrical resistivity that is greater than or equal to 1,000 ohm-cm.
11. The structure of claim 8 wherein the substrate includes a second region comprised of a single-crystal semiconductor material, and the first region is positioned between the second region and the plurality of fins.
12. The structure of claim 8 wherein the second polycrystalline semiconductor material of the plurality of fins has an electrical resistivity that is in a range of about 1,000 ohm-cm to about 10,000 ohm-cm.
13. The structure of claim 8 wherein the second polycrystalline semiconductor material of the plurality of fins has an electrical resistivity that is greater than or equal to 1,000 ohm-cm.
14. The structure of claim 8 wherein the second polycrystalline semiconductor material is polysilicon.
15. The structure of claim 8 wherein the passive device is a transmission line.
16. The structure of claim 8 wherein the passive device is an inductor.
17. The structure of claim 11 wherein the single-crystal semiconductor material of the second region has an electrical resistivity that is less than or equal to 100 ohm-cm.
18. The structure of claim 17 wherein the second polycrystalline semiconductor material of the plurality of fins and the first polycrystalline semiconductor material of the first region each have an electrical resistivity that is in a range of about 1,000 ohm-cm to about 10,000 ohm-cm.
19. The structure of claim 8 further comprising:
a semiconductor layer including a section on each of the plurality of fins.
20. The structure of claim 19 wherein the semiconductor layer comprises a third polycrystalline semiconductor material.