Insitu TEM observation of epitaxial CoSi2 formation on (100) silicon

Abstract

Self-aligned titanium and cobalt silicide layers on silicon (Salicides) have been used as low resistivity metal contacts for advanced CMOS devices. However, the scaling of devices to smaller dimensions places increasing requirements on Salicide properties. Controlling junction consumption, interface roughness, lateral growth, thermal stability and resistivity during silicide formation limit the use of these materials. Epitaxial silicides offer significant advantages over polycrystalline films because of their thermal stability and low resistivity. Epitaxial Ti and Co disilicides have been grown on (111)Si by MBE. Recently, growth of epitaxial Co disilicide on (001)Si has been reported using bimetallic layers of Co and Ti as source materials. Planar CoSi2/Si interfaces with defect free grains have been produced. Uniform low resitivity films are produced using standard processing conditions. The process involves sequential deposition of Ti and Co on (001 )Si. Titanium is a reactive metal which acts as a getter for the residual native oxide on the Si surface and as a reaction barrier between Co and Si at low temperatures.