FinFETs with air-gap spacers and methods for forming the same

Patent metadata

Field	Value
Publication number	US-9831346-B1
Application number	US-201615220990-A
Country	US
Kind code	B1
Filing date	Jul 27, 2016
Priority date	Jul 27, 2016
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

Fin field effect transistors (FinFETs) include air-gaps between adjacent metal contacts and/or between metal contacts and the transistor gate. The air-gaps are formed during non-conformal deposition of an isolation dielectric in conjunction with a metal-first process to form the conductive structures.

First claim

What is claimed as new is:

1. A method of forming a semiconductor device, comprising:
forming a gate structure over a channel region of a semiconductor fin, wherein a source region and a drain region are present on opposing sides of the channel region;
forming dielectric spacers over sidewalls of the gate structure and a dielectric cap over a top of the gate structure;
forming a conductive layer over the dielectric cap, and over the source region and the drain region between the dielectric spacers of adjacent gate structures;
forming an isolation aperture through the conductive layer to a top surface of the dielectric cap; and
forming a dielectric layer within the isolation aperture, wherein a first air gap is formed within the dielectric layer during formation of the dielectric layer, and wherein the isolation aperture extends over sidewalls of the dielectric spacers, and forming the dielectric layer comprises non-conformally depositing the dielectric layer into the isolation aperture and forming the first air gap within the dielectric layer over the top of the gate structure and forming a second air gap over sidewalls of the dielectric spacers.

2. The method of claim 1 , wherein forming the dielectric layer comprises non-conformally depositing the dielectric layer into the isolation aperture and forming the second air gap beneath the dielectric layer over sidewalls of the dielectric spacers.

3. The method of claim 1 , wherein the first air gap over the top of the gate structure and the second air gap over the sidewalls of the dielectric spacers are merged.

4. The method of claim 1 , wherein the first air gap is entirely surrounded by the dielectric layer.

5. A semiconductor device, comprising:
a semiconductor fin disposed over a semiconductor substrate;
a gate structure disposed over a channel region of the semiconductor fin;
source and drain regions on opposing sides of the channel region;
dielectric spacers over sidewalls of the gate structure and a dielectric cap over the top of the gate structure;
a conductive layer over the source region and the drain region between the dielectric spacers of adjacent gate structures; and
an isolation dielectric disposed over the top of the gate structure and extending over sidewalls of the dielectric spacers, wherein the isolation dielectric comprises a first air gap over the top of the gate structure entirely surrounded by the isolation dielectric, and a second air gap over sidewalls of the dielectric spacers.

6. The semiconductor device of claim 5 , wherein a width of the air gap ranges from 30% to 95% of a width of the gate structure.

7. The semiconductor device of claim 5 , wherein the isolation dielectric extending over the sidewalls of the dielectric spacers does not contact the source and drain regions.

8. The semiconductor device of claim 5 , wherein the height of the second air gap over the sidewalls of the dielectric spacers ranges from 30% to 95% of a height of the gate structure.

9. The semiconductor device of claim 5 , wherein a top surface of the conductive layer is above a top surface of the gate structure.

10. The semiconductor device of claim 5 , wherein the dielectric spacers comprise silicon carbon nitride and the dielectric cap comprises silicon nitride.

11. The semiconductor device of claim 5 , wherein the isolation dielectric comprises silicon dioxide.

Assignees

• Globalfoundries Inc

Inventors

• Zang Hui
• Chi Min-Hwa

Classifications

• H10D64/01354

  passivation or protection of the electrode, e.g. using re-oxidation · CPC title

• H10D64/0112

  using conductive layers comprising silicides · CPC title

• H10W20/072

  of dielectric parts comprising air gaps · CPC title

• H10W20/48

  Insulating materials thereof · CPC title

• H10W20/47

  comprising two or more dielectric layers having different properties, e.g. different dielectric constants · CPC title