Process for making polycide structures

TL;DR: An improved method for making polycide structures for use in electrode and wiring interconnection applications is described in this paper, which consists of depositing a layer of polysilicon on an insulating layer and forming on this poly-silicon layer a silicide structure and a silicon capping layer.

Abstract: An improved method for making polycide structures for use in electrode and wiring interconnection applications. It includes depositing a layer of polysilicon on an insulating layer and forming on this polysilicon layer a silicide structure and a silicon capping layer. The deposited layers are defined and etched through dry etching techniques using a dry etching mask made of a refractory metal that does not form a volatile halide in a dry etching environment. Metals with such characteristics include cobalt (Co), nickel (Ni), iron (Fe), and manganese (Mn). The metal mask and the other deposited layers may be formed and defined using a photoresist mask as a deposition mask formed to be compatible with lift-off techniques. The silicide may be deposited either through a chemical vapor deposition process or through evaporation techniques. If it is formed through the co-evaporation of metal and silicon, then the structure is subjected to a low temperature reaction annealing step at a temperature between 500° and 600° C. prior to dry etching. To avoid a diffusion of the metal mask into the silicon layer, during this low temperature annealing, the process provides for the formation of a diffusion barrier layer between the metal mask and the silicon layer. Following the removal of the metal mask and the diffusion barrier layer, the structure is annealed at a temperature sufficient to cause the homogenization of the silicide layer.