A novel CoSi₂ thin film process with improved thicknessscalability and thermal stability

摘要

Novel silicidation processes have been developed to improve thethermal stability of thin CoSi₂ films (250 Å to 1200Å) by the following silicidation schemes: (1) using as-depositedamorphous Si gate, (2) applying light nitridation to the silicon surfacebefore depositing metals, and (3) using a Co/Ti bilayer technique forgrowing epitaxial CoSi₂ layer. Individually, each of thethree schemes provides improved thermal stability, while a highly stableCoSi₂ film on both polysilicon and Si substrate can beobtained by combining these three schemes, in which theCoSi₂/Si structure is stable up to 1100° C/30 s and theCoSi₂/polysilicon structure is stable up to 1000° C/30 s