Vertical transport field-effect transistor including replacement gate
A vertical transport field-effect transistor array includes continuous spacers at cell edges that are formed following a replacement metal gate process. Techniques for fabricating the transistor array include forming trenches extending along the fin edges of the array to provide access to sacrificial gates, replacing the sacrificial gates with gate stacks, and forming the continuous spacers to encapsulate the gate stacks once formed. Removal of interlevel dielectric material from the array is not required for gate replacement. Bottom source/drain contacts may be formed in the trenches and in adjoining relation to the continuous spacers.
1. A vertical device comprising:
a cell comprising nFET and pFET regions;
vertical transport field-effect transistors within the nFET and pFET regions, the vertical transport field-effect transistors including gate stacks comprising gate dielectric layers and gate metal layers;
a first cell edge adjoining the nFET region and including a first pair of parallel continuous dielectric spacers, one of the first pair of continuous dielectric spacers being in direct contact with the gate metal layers in the nFET region;
a second cell edge adjoining the pFET region and including a second pair of parallel continuous dielectric spacers, one of the second pair of continuous dielectric spacers being in direct contact with the gate metal layers in the pFET region;
a first electrically conductive bottom source/drain contact in a first trench between the first pair of continuous dielectric spacers;
a second electrically conductive bottom source/drain contact in a second trench between the second pair of continuous dielectric spacers;
a semiconductor substrate beneath the first and second pairs of continuous dielectric spacers; and
parallel semiconductor fins extending vertically from the semiconductor substrate, the semiconductor fins including channel regions adjoining the gate stacks, the first and second pairs of continuous dielectric spacers running perpendicular to the parallel semiconductor fins when viewed in a top plan view.
2. An array of vertical transport field-effect transistors, comprising:
a semiconductor substrate;
parallel semiconductor fins extending vertically with respect to the semiconductor substrate, each of the semiconductor fins including side walls and inner and outer end walls;
a plurality of vertical transport field-effect transistors, each of the vertical transport field-effect transistors comprising a bottom source/drain region, a top source/drain region, and a channel between the bottom source/drain region and the top source/drain region, the channel comprising a channel region of one of the semiconductor fins, and a gate stack adjoining the channel region;
a first pair of parallel, continuous dielectric side wall spacers extending perpendicularly with respect to the semiconductor fins when viewed in a top plan view and vertically with respect to the semiconductor substrate, the first pair of parallel, continuous dielectric side wall spacers being proximal to the outer end walls of a first plurality of the semiconductor fins and bounding a first trench, one of the first pair of parallel, continuous dielectric side wall spacers adjoining a plurality of the gate stacks of a first plurality of the vertical transport field-effect transistors;
a second pair of parallel, continuous dielectric side wall spacers extending perpendicularly with respect to the semiconductor fins when viewed in a top plan view and vertically with respect to the semiconductor substrate, the second pair of parallel, continuous dielectric side wall spacers being proximal to the outer end walls of a second plurality of the semiconductor fins and bounding a second trench, one of the second pair of parallel, continuous dielectric side wall spacers adjoining a plurality of the gate stacks of a second plurality of the vertical transport field-effect transistors;
a first bottom source/drain contact layer between the first pair of parallel, continuous side wall spacers;
a second bottom source/drain contact layer between the second pair of parallel, continuous side wall spacers;
a first recess extending vertically from the first trench into the semiconductor substrate, the first recess being filled with electrically insulating material;
a second recess extending vertically from the second trench into the semiconductor substrate, the second recess being filled with electrically insulating material.
3. The array of vertical transport field-effect transistors of claim 2 , wherein the plurality of the vertical transport field-effect transistors comprise n-type vertical transport field-effect transistors and p-type vertical transport field-effect transistors, the n-type vertical transport field-effect transistors being within an nFET region and the p-type vertical transport field-effect transistors being within a pFET region, the first pair of parallel, continuous dielectric side wall spacers adjoining the nFET region and the second pair of parallel, continuous side wall spacers adjoining the pFET region.
4. The array of vertical transport field-effect transistors of claim 3 , wherein each of the gate stacks includes a work function metal and a gate dielectric layer, one of the first pair of parallel, continuous dielectric side wall spacers directly contacting the work function metal of the gate stacks in the nFET region and one of the second pair of parallel, continuous dielectric side wall spacers directly contacting the work function metal of the gate stacks in the pFET region.
5. The array of vertical transport field-effect transistors of claim 3 , further comprising an interlevel dielectric layer between the semiconductor fins and adjoining the first and second pairs of parallel, continuous dielectric side wall spacers, the dielectric side wall spacers having top surfaces coplanar with a top surface of the interlevel dielectric layer.
6. The array of vertical transport field-effect transistors of claim 5 , wherein each of the vertical transport field-effect transistors further comprises a top dielectric spacer above the gate stack and adjoining the top source/drain region, one of the first pair of parallel, continuous dielectric side wall spacers directly contacting a plurality of the top dielectric spacers in the nFET region and one of the second pair of parallel, continuous dielectric side wall spacers directly contacting a plurality of the top dielectric spacers in the pFET region.
7. The array of vertical transport field-effect transistors of claim 2 , wherein the first and second recesses are in an offset relation to ends of the semiconductor fins in the top plan view.
8. The array of vertical transport field-effect transistors of claim 7 , further comprising a bottom dielectric spacer outward of the substrate, wherein the first and second pairs of parallel continuous dielectric spacers extend from the bottom dielectric spacer and the first and second electrically conductive bottom source/drain contacts terminate at the bottom dielectric spacer when viewed in cross section along the fins.
9. The vertical device of claim 1 , further comprising:
a first recess extending vertically downwardly from the first trench and into the semiconductor substrate;
a second recess extending vertically downwardly from the second trench and into the semiconductor substrate; and
electrically insulating material filling the first and second recesses;
wherein the first and second recesses are in an offset relation to ends of the semiconductor fins in the top plan view.
10. The vertical device of claim 9 , further comprising a bottom dielectric spacer outward of the substrate, wherein the first and second pairs of parallel continuous dielectric spacers extend from the bottom dielectric spacer and the first and second electrically conductive bottom source/drain contacts terminate at the bottom dielectric spacer when viewed in cross section along the fins.