Wrap around contact for nanosheet source drain epitaxy
Embodiments of the invention include a method for fabricating a semiconductor device and the resulting structure. A nanosheet stack of alternating nanosheets of a sacrificial semiconductor material and a semiconductor channel material located on a substrate is provided. An additional dielectric spacer is formed on the dielectric spacer and within a gap. Dielectric spacer is removed. An epitaxial oxide layer is formed on the re-exposed recessed surfaces of the substrate. Germanium is formed on the epitaxial oxide layer. Sidewalls of each semiconductor channel material nanosheet are physically exposed. A source/drain is formed on a surface of the germanium. ILD material is formed above each source/drain and above an adjacent region. Portions of ILD material are removed such that sidewalls of the source/drain and germanium are exposed. The germanium is removed. A contact region is formed that wraps around the source/drain region.
1. A semiconductor structure comprising:
a plurality of stacked and suspended semiconductor channel material nanosheets located above a semiconductor substrate;
a functional gate structure surrounding a portion of each semiconductor channel material nanosheet of the plurality of stacked and suspended semiconductor channel material nanosheets, the functional gate structure comprising a gate dielectric portion and a gate conductor portion;
a source/drain region on each side of the functional gate structure and physically contacting sidewalls of each semiconductor channel material nanosheet of the plurality of stacked and suspended semiconductor channel material nanosheets;
a contact region wrapping completely around a portion of each source/drain region such that (i) a top surface of the contact region is coplanar with a top surface of the gate conductor portion of the functional gate structure and (ii) a bottom surface of the contact region is lower than a bottom surface of the functional gate; and
an epitaxial oxide layer between the contact region and the semiconductor substrate, a top surface of the epitaxial oxide layer coplanar with a top surface of the semiconductor substrate.
2. The semiconductor structure of claim 1 , wherein the contact region includes a silicide layer physically contacting and wrapping around each source/drain region.
3. The semiconductor structure of claim 1 , wherein each of the stacked and suspended semiconductor channel material nanosheets comprises at least three nanosheets.
4. The semiconductor structure of claim 1 , further comprising an interlevel dielectric (ILD) material located directly on a surface of each source/drain region and laterally adjacent to each contact region.
5. The semiconductor structure of claim 4 , further comprising a region that includes a shallow trench isolation (STI) material that is physically contacting the ILD material and the contact region.
6. The semiconductor structure of claim 5 , wherein:
the STI material is beneath the ILD material;
the STI material is beneath and laterally adjacent to the contact region.
7. The semiconductor structure of claim 5 , wherein the STI material is physically contacting the semiconductor substrate.
8. The semiconductor structure of claim 1 , further comprising inner gate spacers (i) contacting sidewalls of the functional gate structure, (ii) located on an outer portion of each semiconductor channel material nanosheet of the plurality of stacked and suspended semiconductor channel material nanosheets, and (iii) contacting sidewalls of the source/drain region.
9. The semiconductor structure of claim 1 , wherein the sidewalls of each semiconductor channel material nanosheet of the plurality of stacked and suspended semiconductor channel material nanosheets are vertically aligned to one another.
10. The semiconductor structure of claim 1 , wherein:
the gate dielectric portion physically contacts the semiconductor channel material nano sheet; and
the gate conductor portion physically contacts the gate dielectric portion.
11. The semiconductor structure of claim 1 , wherein the semiconductor substrate and each semiconductor channel material nanosheet is composed of a same semiconductor material.