Doping with solid-state diffusion sources for finFET architectures
An impurity source film is formed along a portion of a non-planar semiconductor fin structure. The impurity source film may serve as source of an impurity that becomes electrically active subsequent to diffusing from the source film into the semiconductor fin. In one embodiment, an impurity source film is disposed adjacent to a sidewall surface of a portion of a sub-fin region disposed between an active region of the fin and the substrate and is more proximate to the substrate than to the active area.
1. A CMOS circuit structure comprising:
a PMOS transistor structure, further comprising:
a first fin comprising silicon and including a first region over a second region;
a gate stack adjacent to a sidewall surface of the first region, wherein the gate stack includes a gate dielectric and a gate electrode;
a source and a drain; and
a first dielectric layer comprising an impurity associated with a first silicon conductivity type, the first dielectric layer adjacent to a sidewall surface of the second region,
wherein the impurity is also present within the second region;
an NMOS transistor structure, further comprising:
a second fin comprising silicon and including a third region over a fourth region;
a gate stack adjacent to a sidewall surface of the third region, wherein the gate stack includes a gate dielectric and a gate electrode;
a source and a drain; and
a second dielectric layer lacking the impurity, the second dielectric layer adjacent to a sidewall surface of the fourth region, wherein the impurity is also absent from the fourth region; and
an isolation material separating the first fin from the second fin, wherein the isolation material is adjacent to the first dielectric layer and adjacent to the second dielectric layer.
2. The CMOS circuit CMOS structure of claim 1 , wherein:
the first dielectric layer comprises a phosphorus-doped silicate glass (PSG); and
the impurity is phosphorus.
3. The CMOS circuit structure of claim 1 , wherein the dielectric layer is in contact with at least one of the gate electrode or gate dielectric.
4. The CMOS circuit structure of claim 1 , wherein:
the first region has a lateral width less than 20 nm;
the fin has a vertical height of between 20 nm and 150 nm; and
the first dielectric layer has a thickness between 1 nm and 5 nm as measured normal to the sidewall surface.
5. The CMOS circuit structure of claim 1 , wherein the first dielectric layer has a substantially conformal thickness.
6. The CMOS circuit structure of claim 1 , wherein the second dielectric layer comprises a second impurity associated with a second silicon conductivity type, complementary to the first silicon conductivity type, the second impurity also present within the lower region.
7. The CMOS circuit structure of claim 6 , wherein the isolation material is separating the first dielectric layer from the second dielectric layer.
8. The CMOS circuit structure of claim 7 , wherein the isolation material comprises a plurality of dielectric layers including a silicon nitride layer that is adjacent to the first dielectric layer and the second dielectric layer.
9. The CMOS circuit structure of claim 6 , wherein:
the first dielectric layer comprises a phosphorus-doped silicate glass (PSG);
the second dielectric layer comprises a boron-doped silicate glass (BSG).
10. The CMOS circuit structure of claim 8 , wherein:
the first dielectric layer and second dielectric layer are layers of a material stack that is adjacent to a sidewall surface of at least one of the second region or the fourth region.
11. The CMOS circuit structure of claim 10 , wherein the material stack of layers further comprises a silicon nitride layer between the first and second dielectric layers.
12. The CMOS circuit structure of claim 6 , wherein the first region comprises the first impurity at a concentration of between 10e17 and 10e19 cm-3.
13. The CMOS circuit structure of claim 12 , wherein the fourth region comprises the second impurity at a concentration of between 10e17 and 10e19 cm-3.
14. The CMOS circuit structure of claim 1 , wherein the first dielectric layer extends over a substrate surface that intersects the sidewall surface of the second region, a portion of the first dielectric layer over the substrate surface and located between the isolation dielectric and the substrate surface.
15. The CMOS circuit structure of claim 1 , wherein:
the first region has a lateral width less than 20nm;
the first fin has a vertical height of between 20 nm and 150nm; and
the first dielectric layer has a thickness between 1 nm and 5 nm as measured normal to the sidewall surface of the second region.