Selective titanium nitride strip

Details Selective titanium nitride strip Selective titanium nitride strip

1998-10-06

2001-03-13

Gulakowski, Randy (Department: 1746)

Semiconductor device manufacturing: process

Chemical etching

Liquid phase etching

C438S648000, C438S649000, C216S100000

Reexamination Certificate

active

06200910

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to electronic semiconductor devices, and, more particularly, to fabrication methods for such devices.
Semiconductor integrated circuits with high device density require minimum size structures such as short gates and shallow source/drain junctions for field effect transistors (“FET”s), small area emitters for bipolar transistors, and narrow interconnection lines between devices. Short gates and narrow interconnection lines lead to higher resistance for the typical polysilicon gates and first level interconnection lines, and this increases RC time delays and slows circuit operation.
One approach to reduce the resistance of polysilicon gates and interconnection lines uses a self-aligned titanium silicide on top of the polysilicon. The silicidation process first deposits a blanket film of titanium metal and then reacts the titanium with any underlying silicon in a nitrogen atmosphere. Lastly, the process removes the titanium nitride formed from the titanium which did not become silicide. For example, see U.S. Pat. No. 4,821,085.
The removal of titanium nitride in this self-aligned silicide process requires a very high selectivity with respect to removal of the titanium silicide, otherwise the titanium silicide will be thinned and lose the advantages of siliciding. The removal of titanium nitride with the standard basic SC1 solution (12.5% ammonium hydroxide solution, 12.5% hydrogen peroxide solution, and 75% water) at room temperature has a selectivity with respect to titanium silicide of roughly 7.8 to 1. This low selectively presents problems in the known silicide processes.
SUMMARY OF THE INVENTION
The present invention provides a highly selective etch of titanium nitride and titanium metal with respect to titanium silicide by the use of a solution with a large hydrogen peroxide to ammonium hydroxide ratio.
Further, the present invention provides a self-aligned silicide process which selectively removes titanium nitride with respect to titanium silicide with a hydrogen peroxide solution and then removes titanium silicide filaments after a phase conversion anneal with a hydrogen peroxide plus ammonium hydroxide solution.
Advantages of the invention include a simple method for removal of titanium nitride with high selectivity with respect to titanium silicide and a simple self-aligned silicide process.


REFERENCES:
patent: 5395798 (1995-03-01), Havemann
patent: 5776822 (1998-07-01), Fujii et al.
patent: 5-206133 (1993-11-01), None

Affiliated with

Also associated with

Rating

Selective titanium nitride strip does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Selective titanium nitride strip, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Selective titanium nitride strip will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2488145