Switches in bulk substrate
The present disclosure relates to semiconductor structures and, more particularly, to switches in a bulk substrate and methods of manufacture. The structure includes: at least one active device having a channel region of a first semiconductor material; a single air gap under the channel region of the at least one active device; and a second semiconductor material being coplanar with and laterally bounding at least one side of the single air gap, the second semiconductor material being different material than the first semiconductor material.
1. A structure comprising:
a first region comprising:
a plurality of switches each of which comprise a channel region of semiconductor substrate and source/drain regions;
a single air gap located under the channel region and extending to inner source/drain regions of the plurality of switches; and
a semiconductor material coplanar with and bounding at least one side of the single air gap, the semiconductor material being different than the semiconductor substrate; and
a second region devoid of the single air gap and comprising at least one device positioned over the semiconductor material.
2. The structure of claim 1 , wherein the plurality of switches comprise radio frequency (RF) switches and the semiconductor material is under outermost source/drain regions of the RF switches.
3. The structure of claim 1 , wherein the semiconductor material comprises Ge material and the semiconductor substrate comprises single crystalline Si material.
4. The structure of claim 1 , further comprising shallow trench isolation structures extending below the single air gap, with insulator material of the shallow trench isolation structures sealing the single air gap.
5. The structure of claim 1 , wherein the semiconductor material laterally bounds and supports the channel region and the single air gap does not extend laterally beyond a patterned active shape of the plurality of switches.
6. The structure of claim 5 , wherein the semiconductor material remains under a body contact region of the plurality of switches.
7. The structure of claim 1 , wherein the semiconductor material comprises material different than the semiconductor substrate.
8. The structure of claim 1 , further comprising a slit adjacent to common source/drain regions of adjacent switches of the plurality of switches, and the semiconductor material remaining as pillars under channel regions of selected switches remote from the adjacent switches.