SRAM Devices Utilizing Strained-Channel Transistors and Methods of Manufacture

摘要

A novel SRAM memory cell structure and method of making the same are provided. The SRAM memory cell structure comprises strained PMOS transistors formed in a semiconductor substrate. The PMOS transistors comprise epitaxial grown source/drain regions that result in significant PMOS transistor drive current increase. An insulation layer is formed atop an STI that is used to electrically isolate adjacent PMOS transistors. The insulation layer is substantially elevated from the semiconductor substrate surface. The elevated insulation layer facilitates the formation of desirable thick epitaxial source/drain regions, and prevents the bridging between adjacent epitaxial layers due to the epitaxial layer lateral extension during the process of growing epitaxial sour/drain regions. The processing steps of forming the elevated insulation layer are compatible with a conventional CMOS process flow.