Tungsten plug technology using substitution of W for Si

Novel W plug technology that is compatible with a conventional poly Si filling has been developed. In this technology, low-pressure chemical vapor deposition (LPCVD) poly Si is embedded in contacts and vias using etchback, and tungsten (W) is substituted for poly Si using Si reduction of WF/sub 6/. This plug technology has been successfully applied to a 0.6- mu m contact and a via filling. The specific contact resistivity was 2*10/sup -7/ and 4*10/sup -7/ Omega -cm/sup 2/ for n/sup +/ and p/sup +/ contacts, respectively. For vias on W and WSi/sub 2/ polycide interconnections, the contact resistivity is found to be less than 1*10/sup -8/ Omega -cm/sup 2/. The amount of W substituted for Si by this reaction is determined by several process parameters: thin oxides on Si surfaces, deposition temperature, and partial pressure of WF/sub 6/. W films that are more than 1.5- mu m thick can be substituted for Si in this technology.<
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