Vertical transistor transmission gate with adjacent NFET and PFET
A complementary metal oxide semiconductor (CMOS) vertical transistor structure with closely spaced p-type and n-type vertical field effect transistors (FETs) is provided. After forming a dielectric material portion contacting a proximal sidewall of a first semiconductor fin for formation of a p-type vertical FET and a proximal sidewall of a second semiconductor fin for formation of an n-type vertical FET, a first gate structure is formed contacting a distal sidewall of the first semiconductor fin, and a second gate structure is formed contacting a distal sidewall of the second semiconductor fin. Because no gate structures are formed between the first and second semiconductor fins, the p-type vertical FET is spaced from the n-type FET only by the dielectric material portion.
1. A method of forming a semiconductor structure comprising:
forming a first doped bottom semiconductor portion over a first region of a semiconductor substrate;
forming a second doped bottom semiconductor portion over a second region of the semiconductor substrate;
forming a sacrificial gate layer over the first doped bottom semiconductor portion and the second doped bottom semiconductor portion;
forming a dielectric capping layer over the sacrificial gate layer;
forming a first semiconductor fin within a first trench extending through the dielectric capping layer and the sacrificial gate layer, wherein the first semiconductor fin contacts a surface of a portion of the first doped bottom semiconductor portion;
forming a second semiconductor fin in a second trench extending through the dielectric capping layer and the sacrificial gate layer, wherein the second semiconductor fin contacts a surface of a portion of the second doped bottom semiconductor portion;
removing entire portions of the dielectric capping layer and the sacrificial gate layer located between the first semiconductor fin and the second semiconductor fin to provide an opening exposing a proximal sidewall of the first semiconductor fin and a proximal sidewall of the second semiconductor fin;
forming a dielectric fill portion within the opening, the dielectric fill portion contacting the proximal sidewall of the first semiconductor fin and the proximal sidewall of the second semiconductor fin;
removing the sacrificial gate layer to expose a channel portion of the first semiconductor fin and a channel portion of the second semiconductor fin;
forming a first gate structure along sidewalls of the channel portion of the first semiconductor fin that are not covered by the dielectric fill portion and a second gate structure along sidewalls of the channel portion of the second semiconductor fin that are not covered by the dielectric fill portion;
removing the dielectric capping layer to expose a top portion of each of the first semiconductor fin and the second semiconductor fin;
forming a first doped top semiconductor portion surrounding the top portion of the first semiconductor fin; and
forming a second doped top semiconductor portion surrounding the top portion of the second semiconductor fin.
2. The method of claim 1 , further comprising forming a first dielectric cap over the first semiconductor fin within the first trench and a second dielectric cap over the second semiconductor fin within the second trench, wherein a top surface of each of the first dielectric cap and the second dielectric cap is coplanar with a top surface of the dielectric capping layer, and wherein the opening exposes a proximal sidewall of the first dielectric cap and a proximal sidewall of the second dielectric cap, and wherein the removing the dielectric capping layer exposes the first dielectric cap and the second dielectric cap.
3. The method of claim 2 , further comprising forming sacrificial sidewall spacers on sidewalls of the top portion of each of the first semiconductor fin and the second semiconductor fin, the first dielectric cap and the second dielectric cap prior to the removing the sacrificial gate layer.
4. The method of claim 3 , further comprising forming an interlevel dielectric (ILD) portion over the dielectric fill portion to completely fill the opening.
5. The method of claim 4 , further comprising forming an ILD layer over the first doped bottom semiconductor portion and the second doped bottom semiconductor portion, wherein the ILD layer laterally surrounds the first gate structure, the second gate structure and the sacrificial sidewall spacers.
6. The method of claim 5 , wherein the forming the first doped top semiconductor portion comprises:
removing the sacrificial sidewall spacers present on the sidewalls of the top portion of the first semiconductor fin and the first dielectric cap to provide a first cavity; and
epitaxially depositing a first semiconductor material in the first cavity.
7. The method of claim 6 , wherein the forming the second doped top semiconductor portion comprises:
removing the sacrificial sidewall spacers present on the sidewalls of the top portion of the second semiconductor fin and the second dielectric cap to provide a second cavity; and
epitaxially depositing a second semiconductor material in the second cavity.
8. The method of claim 1 , further comprising forming a first shared contact structure connecting the first doped top semiconductor portion and the second doped top semiconductor portion.
9. The method of claim 1 , further comprising forming a first oxide layer on sidewall surfaces of the sacrificial gate layer that are exposed by the first trench prior to the forming the first semiconductor fin, and a second oxide layer on sidewall surfaces of the sacrificial gate layer that are exposed by the second trench prior to the forming the second semiconductor fin, and removing the first oxide layer and the second oxide layer prior to the forming the first gate structure and the second gate structure.