Study of Thermal Stress Effect on Rapid Thermal Ultra-thin Gate Oxides

• Main Authors: Rong-Yu Zheng, 鄭容裕
• Other Authors: Jenn-Gwo Hwu
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/06524433193983632747

碩士 === 國立臺灣大學 === 電子工程學研究所 === 91 === Abstract With the ability to perform heat cycles on a wafer rapidly and with low thermal budget, RTP has become a key technology in the fabrication of advanced semiconductor devices. However, the most common criticisms of RTP are about the thermal non-uniformity, and this problem becomes important as oxide thickness shrinks for the need of ULSI devices. In the thesis, the effects of mechanical stress on silicon oxidation and on the related MOS devices were studied. The relation of the thermal stress and the electrical characteristic of MOS capacitor are investigated, This study is a pioneering work on this subject since mechanical stress problems are considered to be one of the most important issues in the next generation of integrated circuit technology. Our works have demonstrated the substantial effects of mechanical stress caused by the variation of the oxidation process temperature on the electrical characteristics of oxides. In chapter 2, the oxidation temperature of our experiment is under 760℃. We first introduce thickness dependent saturation behavior in substrate injection gate current. We propose a new viewpoint to observe the relative oxide thickness distribution from the inverse of the gate injection current. Furthermore, we discuss the electrical characteristics of MOS capacitors. For instance, the geometrical position of the thermal stress effect, the dependence of the substrate injection saturation current on the gate injection leakage current, and the distribution of the substrate injection saturation current under various oxidation temperature. In chapter 3, the oxidation temperature is above 760℃. We first introduce mechanical stress dependent saturation behavior in substrate injection gate current. In order to investigate the effect of stress induced bandgap variation, we use the same analysis method as in chapter 2 to observe the relation of the thermal stress and substrate injection current. And we reproduce the observation by carrying out a second run experiment. Finally, we will get a conclusion about the effect of mechanical stress on ultra-thin gate oxides.