Method of making SRAM cell having single layer polysilicon thin film transistors

摘要

A static metal oxide semiconductor random access memory (SRAM) having NMOS and thin film transistors (TFTs) formed from a single polysilicon layer, and a method for forming the same. The SRAM cell comprises a plurality of NMOS transistors and TFTs that are interconnected by a local interconnect structure. The single layer of poly is used to define the TFT bodies and gates of NMOS transistors in the SRAM cell. Each TFT comprises a single polysilicon layer comprising source gate and drain regions. During the fabrication process, exposed portions of the TFT polysilicon body and exposed regions of NMOS transistors react with a refractory metal silicide to form polycide and silicide regions, respectively. An amorphous silicon pattern also reacts with the refractory metal silicide to form a local interconnect structure connecting the silicided portions of the thin film transistors and the MOS transistors. This arrangement results in a TFT SRAM cell that can be implemented using simple fabrication techniques, such as single poly logic processes or ASIC processes.