| 摘要 |
PURPOSE: To improve withstand voltage and realize high quality and yield, by heat-treating a silicon substrate of specified oxygen concentration in inert gas, and then heat-treating the substrate in an oxidizing atmosphere. CONSTITUTION: The oxygen concentration Oi of a semiconductor substrate (Si wafer) in the initial state (before a wafer process) is set in the range of 14-17×10<17> /cm<3> . Before the first oxidation process, heat treatment is performed in N2 at 700-1000 deg.C for 30 minutes - 5 hours. Thereby the change amount of substrate oxygen concentration which changes during the wafer process is restricted in the range of 5-10×10<17> /cm<3> , so that the yield of gate oxide film withstand voltage can be remarkably improved. For example, when pre-anealing is performed in N2 at 800 deg.C for 30 minutes, remarkable improvement is obtained as compared with the conventional plot, as shown in figure. Thereby the oxide film withstand voltage of a capacitor in an IC and that of a transistor can be remarkably improved, and the yield can be also increased. |
