Study On Methods Of Introducing The Strain Into Si-based Strained Device

With the development of IC industry, traditional method of scaling transistor to improve the performance become more and more limited by cost and technique. Finding new material, new substrate and new device structure become preferred method to improve the performance of transistor. Strained silicon technology enhances the mobility in bulk Si CMOS by introducing tensile or compressive stress into Si device. In addition, based on the process of Bulk Si CMOS, Strained silicon technology needs no complicated methods in the process, thus being widely applied as a cheap and efficient methodology.Due to the change in lattice constant and the distortion of energy band, strained Si exhibits great mobility enhancement compared with the conventional Si material, and it is the critical reason for the wide application of strained Si MOSFETs.The factors which influence the improvement of mobility are studied by energy band theory.How to introduce the strain into silicon is the base of other research, which include global strain, process-induced strain, post-processing strain, hybrid orientation technology and mechanical strain, STI and contact end-stop stress liner which belong to process-induced strain are researched carefully. In STI , the factors influence the strain, strain distribution and the relationship between STI and layout are discussed. STIW model parameter is embedded in BSIM SPICE so that the simulation performance of circuit is improved. In contact end-stop stress liner, how to manufacture the SiN membrane is carefully studied,the theory that is used to create tensile and compressive SiN membrane by PECVD is depicted , two steps UV process method to create tensile SiN membrane is proposed, how to create high compressive SiN membrane is also described. Tensile SiN membrane above 1.6 GPa and compressive SiN membrane above 2.9 GPa are successfully fulfilled through combining different deposit and process. At last, the different methods to introduce the strain into silicon are compared so that a better method is proposed.The transistor performances will have higher improvement if more than two methods are used together, which will be a trend in the future. The optimized method of introducing the strain into silicon has a good guideline on industry.