Method of fabricating a polysilicon-based load circuit for static random-access memory

Abstract

A semiconductor fabrication method is provided for the fabrication of a polysilicon-based load circuit (called poly-load) for SRAM (static random-access memory). In accordance with this method, a lightly doped polysilicon layer is formed. This lightly doped polysilicon layer is doped with an impurity element to a predetermined concentration corresponding to the desired resistive characteristic of the poly-load. Further, this lightly-doped polysilicon layer is partitioned into two parts: a first part to be formed into the desired poly-load and a second part to be formed into a conductive interconnecting line that is electrically connected to the poly-load. After this, a metal silicide layer is formed over the second part of the lightly doped polysilicon layer to serve as the conductive interconnecting line. Next, an ILD (Inter Layer Dielectric) layer is formed over the poly-load and the conductive interconnecting line, and then the ILD layer is subjected to a densification process. This method can help the poly-load retain its specified length, thus allowing the SRAM device to be further reduced in size to a deep submicron level of integration. Moreover, the method can help the conductive interconnecting line have a low sheet resistance, thus reducing the IR drop across each memory cell to allow a SRAM device to be more stable in operation.