Vertical transport field-effect transistor with ring-shaped wrap-around contact
Vertical transport field-effect transistors are formed on active regions wherein the active regions each include a wrap-around metal silicide contact on vertically extending side walls of the active region. Such wrap-around contacts form self-aligned and reliable strapping for SRAM bottom nFET and pFET source/drain regions. Buried contacts of SRAM cells may be used to strap the wrap-around metal silicide contacts with the gates of inverters thereof. Wrap-around metal silicide contacts provide additional contacts for logic FETs and reduce parasitic bottom source/drain resistance.
1. A semiconductor structure comprising:
a semiconductor substrate;
one or more active regions on the semiconductor substrate, each of the one or more active regions comprising:
a plurality of vertical transport field-effect transistors extending vertically with respect to the semiconductor substrate;
merged, bottom source/drain regions for the plurality of the vertical transport field-effect transistors; and
a peripheral side wall extending downwardly from a top surface of the merged, bottom source/drain regions and comprising a metal silicide contact wrapping around the merged bottom source/drain regions; and
shallow trench isolation regions surrounding, respectively, each of the one or more active regions and wherein the shallow trench isolation regions comprise:
a first dielectric liner adjoining the substrate and bottom portions of the peripheral side walls of the active regions;
a first layer of STI dielectric material within the first dielectric liner;
a second dielectric liner on a top surface of the first layer of STI dielectric material and adjoining the metal silicide contact; and
a second layer of STI dielectric material within the second dielectric liner.
2. The semiconductor structure of claim 1 , further including a metal contact contacting the metal silicide contact.
3. The semiconductor structure of claim 2 , wherein the metal contact adjoins a side wall surface of the metal silicide contact.
4. The semiconductor structure of claim 2 , further including:
an interlevel dielectric layer above the substrate and encasing portions of the vertical field-effect transistors; and wherein:
the metal contact comprises a buried contact within the interlevel dielectric layer;
the merged, bottom source/drain regions include a first source/drain region having n-type conductivity and a second source/drain region having p-type conductivity; and
the buried contact electrically straps the metal silicide contact of a first active region with a gate of a vertical transport field-effect transistors of a second active region on the substrate.
5. The semiconductor structure of claim 1 , further including:
semiconductor fins extending from the semiconductor substrate and comprising channel regions of the vertical transport field-effect transistors;
a bottom spacer over the merged, bottom source/drain regions;
top spacers adjoining the semiconductor fins; and
epitaxial top source/drain regions on the semiconductor fins and above the top spacers.
6. The semiconductor structure of claim 1 , wherein:
the one or more active regions include first and second active regions, each of the first and second active regions including merged, bottom source/drain regions having n-type and p-type conductivity, respectively, and vertically extending side walls;
the vertical transport field-effect transistors include first and second sets of transistors, the first set of transistors comprising portions of the first active region and the second set of transistors comprising portions of the second active region, the first and second sets of transistors being configured as a static random access memory cell.
7. The semiconductor structure of claim 6 , further including:
an interlevel dielectric layer encasing portions of the first and second sets of transistors;
first and second buried contacts within the interlevel dielectric layer;
the first buried contact electrically strapping the metal silicide contact wrapped around the merged source/drain regions comprising the first active region with a gate of one of the second set of transistors, the first buried contact extending partially within one of the shallow trench isolation regions; and
the second buried contact electrically strapping the metal silicide contact wrapped around the merged source/drain regions comprising the second active region with a gate of one of the first set of transistors, the second buried contact extending partially within the one of the shallow trench isolation regions.