Use Of Process Induced Strain Fabrication Of Strained Silicon Material

Strained-Si technology can enhance the mobility of carrier, which fetches up the limitation problem of reduced proportional technology. It has been given high priority and used in UDSM technology as a new technique. One of the most important features of Strained-Si technology is that tensile stress can be beneficial in NMOS transistor, while compressive stress can be beneficial in PMOS transistor. In this issue, we focus on inducing tensile and compressive stress into the material by traditional crafts.Firstly, analyze the relationship of the band structure of Si material and the type of stress theoretically. And based on it, discuss the reason why stress can induce the improvement of mobility. Two methods have been introduced in the issue: STI induced stress and Si3N4 cap induced stress.In the STI induced stress experiment, optimization of the whole experiment process and control of several critical processes has been design based on the condition of the State Key Laboratory in UESTC. After using SEM and HXRD tests, we get that STI technology can induce horizontal compressive stress to Si material and the value of stress is closely related to the distance of adjacent slot.For the Si3N4 cap induced stress experiment, two deposition methods (LPCVD, PECVD) have been used. By (004) Symmetric diffraction and (111) Skew-symmetric diffraction, the value of horizontal stress and vertical stress can be calculated. The result shows that both of the two deposition methods can induce stress into Si material. LPCVD process can induce tensile stress into the channel of the transistor while PECVD process can induce compressive stress.In summary, the technology of process inducing stress can be used in CMOS transistor process in combination ways to improve the performance of NMOS and PMOS transistors. The property of this issue is to analyze the different process induced methods and the relationship of stress and the structure parameters. On this base, CMOS transistor will be investigated later.