Impact Of The Stress In Silicon Substrate On The Thermal Oxidation Rate

The semiconductor manufacturing process is developing fast with the guide of Moore’s Law over40years. New problems and challenges are coming up due to the continued reduced size of devices, and the traditional ways which are using the scaled-down size of devices to improve the performance will also face with many cost and technical limitations and troubles. Therefore, the developments of new device structures and materials have become the primary means to further improve transistors’ performance. These problems can be solved with the coming up of strained silicon technology. Strained silicon technology is to add mechanical stress in the conventional bulk silicon devices, so that the channel material lattice deformation occurs, in order to improve the mobility of carriers in the channel. Thereby Strained silicon technology can improve the performance of semiconductor devices. Moreover, strained silicon MOS devices based on bulk silicon process does not require complex technology, so strained silicon technology is more widely used as a cheap and efficient technology.First, this paper introduced the characteristics of strained silicon technology and described the carrier transport properties in strained silicon. Also the developments of strained silicon technology were investigated. New strained silicon technology is becoming more and more important because of the shortcomings of traditional technology. For example, the high cost SiGe virtual substrate technology is not compatible well with conventional CMOS.Since SiO2is an important part of silicon MOS structures and the devices.SiO2can play a protective role on the silicon surface, and it has a great influence on the stability of devices. So the in-depth study on SiO2is extraordinarily important. The principle of thermal oxidation of silicon was described. With the reaction proceeding, oxygen atom is more difficult to penetrate the SiO2layer to react with Si. The information about the calculation of the stress applied to devices with the self-designed strained equipment was also introduced. This equipment can add mechanical stress to substrates, including uniaxial tensile stress, uniaxial compressive stress, biaxial tensile stress and biaxial compressive stress. Then strained silicon MOS structures were manufactured by thermal evaporation, lithography and other micro-processing technology.Then, C-V curves were measured. It was found that the oxidation rate was slowing down after the silicon substrate was strained. And the high-resolution TEM graphics also confirmed this result. Higher energy was need to break silicon bond and SiO2film was more difficult to break through after strained.Finally, how the mechanical strained silicon influence the surface state and performance of MOSFETs was the most important for future study.