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STRESS REDUCTION IN TiSi2 FILMS

IP.com Disclosure Number: IPCOM000039037D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Thompson, RD: AUTHOR [+2]

Abstract

TiSi2 is an attractive material for transistor gate and interconnect metallurgy due to its low resistivity. One of the major difficulties associated with this material is that production of the lowest resistivity films, either from reaction of Ti with Si or by annealing a co-deposited TiSi2 film, can require annealing temperatures in excess of 800oC in order to obtain sufficiently low resistivity. The figure shows the resistivity of TiSi2 films deposited on silicon and on SiO2, for different temperatures. From this, it is apparant that lower annealing temperatures can be used to crystallize TiSi2 films deposited on Si in order to obtain the desired resistivity, as compared to the temperatures that are required when TiSi2 is deposited on SiO2 .

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STRESS REDUCTION IN TiSi2 FILMS

TiSi2 is an attractive material for transistor gate and interconnect metallurgy due to its low resistivity. One of the major difficulties associated with this material is that production of the lowest resistivity films, either from reaction of Ti with Si or by annealing a co-deposited TiSi2 film, can require annealing temperatures in excess of 800oC in order to obtain sufficiently low resistivity. The figure shows the resistivity of TiSi2 films deposited on silicon and on SiO2, for different temperatures. From this, it is apparant that lower annealing temperatures can be used to crystallize TiSi2 films deposited on Si in order to obtain the desired resistivity, as compared to the temperatures that are required when TiSi2 is deposited on SiO2 . These lower temperatures will reduce the stress built up during cooling due to the difference in thermal co-efficients of expansion. It is thought that the Si interface facilitates this reaction at lower temperatures by providing nucleation sites as well as source/sink capabilities should the as- deposited composition be slightly off stoichiometry. This would make it crucial that the native oxide (SiO2) be removed prior to the TiSi2 deposition, as it will block these capabilities of the Si interface. To remove the native oxide, the Si (or poly-Si) surface can be bombarded by an ion beam in the KeV energy range or approximately 100 o of Ti can be deposited prior to the TiSi2 co-deposition.

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