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High Conductivity Nickel Silicide Polycide Gates for Sub-Micron Field Effect Transistors

IP.com Disclosure Number: IPCOM000038167D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Geiss, P: AUTHOR [+2]

Abstract

Low resistance gate electrodes and very shallow, low leakage, source and drain junctions are obtained by a dual salicide process. A nickel salicide (NiSi) process is used on polysilicon gate electrodes and a titanium or cobalt salicide (TiSi2 or CoSi2) process on junctions.

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High Conductivity Nickel Silicide Polycide Gates for Sub-Micron Field Effect Transistors

Low resistance gate electrodes and very shallow, low leakage, source and drain junctions are obtained by a dual salicide process. A nickel salicide (NiSi) process is used on polysilicon gate electrodes and a titanium or cobalt salicide (TiSi2 or CoSi2) process on junctions.

First, polysilicon is etched to define gate electrodes for both N and P channel devices in a complementary metal oxide silicon (CMOS) process, and source (S) and drain (D) junction areas are defined. Standard sequential implant processing is used to form N+ and P+ junctions. Titanium (Ti) or cobalt (Co) is deposited and reacted with exposed Si in S and D junctions to form a silicide, TiSi2 or CoSi2 . Remaining unreacted metal, Ti or Co, is removed by wet etching. Next, a brief oxidizing anneal is used to form a passivating oxide (SiO2) over the silicide. Ni is deposited and reacted with the polysilicon gate electrodes at a temperature in the range of 350 to 850 degrees Celsius to assure formation of NiSi. Higher temperature results in the formation of undesired, higher resistivity silicide, NiSi2 . Unreacted nickel is etched away as is conventional in a salicide process, and standard processing is used to complete the CMOS integrated circuit.

This process results in low resistance contacts to very shallow S/D junctions having low leakage and high conductivity gate electrodes.

Disclosed anonymously.

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