Method of implementing buried FET below and beside FinFET on bulk substrate
A method and circuit for implementing an enhanced transistor topology enabling enhanced current capability with added device drive strength with buried field effect transistors (FETs) below and beside a traditional FinFET on a bulk substrate, and a design structure on which the subject circuit resides are provided. Buried field effect transistors (FETs) are formed on either side and under the traditional FinFET. The gate of the FinFET becomes the gate of the parallel buried (FETs) and allows self alignment to the underlying sources and drains of the buried FET devices in the bulk semiconductor.
1. A method for implementing an enhanced transistor topology enabling enhanced current capability comprising:
forming a fin field effect transistor (FinFET); said FinFET on a semiconductor substrate; forming said FinFET having in-line source and drain regions without a dog-bone shape and forming a gate region on a gate dielectric with first and second gate extensions extending past opposing sides of said in-line source and drain regions;
forming a first field effect transistor (FET) in said semiconductor substrate beside and under said FinFET and forming a second FET in said semiconductor substrate beside and under said FinFET; forming each of said first FET and said second FET having buried source and drain diffusions formed in said semiconductor substrate on the opposing sides of said in-line source and drain regions with angled implants used to dope said buried source and drain diffusions and FinFET; and said first and second gate extensions of said FinFET providing a gate of said first FET and said second FET; and
forming an electrical bar contact to a common source of said FinFET, said first FET and said second FET.
2. The method as recited in claim 1 wherein forming said FinFET includes using FinFET processing operations and forming a blanket spacer over said FinFET and the semiconductor substrate.
3. The method as recited in claim 2 includes providing source and drain angled implants through said blanket spacer into buried source and drain diffusions in said semiconductor substrate.
4. The method as recited in claim 3 further includes activating each of said implanted regions including said buried source and drain diffusions by one or more anneals of said FinFET.
5. The method as recited in claim 3 further includes anisotropically etching to remove said blanket spacer from horizontal surfaces.
6. The method as recited in claim 5 further includes using FinFET processing operations for forming an electrical contact to the gate of said FinFET, said first FET and said second FET.
7. The method as recited in claim 5 further includes forming an electrical bar contact to a common drain of said FinFET, said first FET and said second FET.