Study on uniaxial stress intensity of MOS channels along different crystal planes induced by SiN-film

Abstract

The process conditions for depositing SiN film on small-sized MOS along different crystal face channels to introduce stress are the same. However, since the elastic stiffness coefficient of channel Si material is anisotropic, the stress intensity introduced in small-sized MOS channels along different crystal planes is different. It is necessary to consider it while designing and manufacturing small-sized strained MOS. In this paper, the uniaxial strained Si PMOS and NMOS with 40 nm channel along different crystal faces were produced by compressive stress and tensile stress SiN film respectively. Quantitative results of uniaxial stress intensity of MOS channel along different crystal planes induced by the same process SiN films were obtained by measuring device transfer characteristics and corresponding theoretical calculations. The results indicate that, for strained NMOS induced by the tensile stress SiN film, (100) and (110) crystal plane channels are subjected to 0.8 GPa and 1.6 GPa tensile stress; for strained PMOS induced by the compressive stress SiN film, (100), (110), and (111) crystal plane channels are subjected to compressive stresses of 1.1 GPa, 0.8 GPa and 1.6 Gpa, respectively.