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Palladium Silicide Contact Resistance Stabilization by Ion Implantation

IP.com Disclosure Number: IPCOM000048176D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Rausch, W: AUTHOR [+2]

Abstract

The contact resistance degradation exhibited by source/ drain contacts has been identified as a grain boundary diffusion controlled process. The thermal instability of the palladium silicide contact metallurgy results in the precipitation of high resistivity silicon at the N+ silicon/Pd(2)Si interface during 400 degree C annealing. The formation of silicon precipitates in the contact and/or a P-N junction under the contact can be prevented by increasing the rate at which silicon diffuses in this region, as seen in polysilicon contacts. Low energy inert ions or dopant, such as argon, xenon, boron, arsenic or phosphorus, implanted prior to the palladium deposition can be used to create an amorphous silicon surface layer in which diffusion is enhanced.

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Palladium Silicide Contact Resistance Stabilization by Ion Implantation

The contact resistance degradation exhibited by source/ drain contacts has been identified as a grain boundary diffusion controlled process. The thermal instability of the palladium silicide contact metallurgy results in the precipitation of high resistivity silicon at the N+ silicon/Pd(2)Si interface during 400 degree C annealing. The formation of silicon precipitates in the contact and/or a P-N junction under the contact can be prevented by increasing the rate at which silicon diffuses in this region, as seen in polysilicon contacts. Low energy inert ions or dopant, such as argon, xenon, boron, arsenic or phosphorus, implanted prior to the palladium deposition can be used to create an amorphous silicon surface layer in which diffusion is enhanced.

An example of this process used ion implanting argon ions in the contact holes prior to the palladium film deposition. The argon ion doses used were 5x10/14/ ions per sq cm and 3x10/15/ ions per sq cm at an energy of 26 KeV. The implant energy and doses were chosen so that an amorphous silicon layer was formed on the contact surface.

About 500 Angstrom of palladium were deposited on the amorphous contact surface. The resulting structures were annealed at 400 degree C in forming gas for 20 minutes to form palladium silicide (Pd(2)Si). A metal, such as aluminum copper, was formed over the surface in the desired pattern to contact the Pd(2)Si contact...