| 摘要 |
PROBLEM TO BE SOLVED: To improve the device characteristics such as enhancement of gate dielectric strength and reduction of junction leak, etc., by collecting internal impurity and minute defects to the rear side of the wafer with a polycrystal Si layer formed on the rear surface of wafer and oxygen precipitates within the wafer to eliminate defects at the area near the surface. SOLUTION: When a wafer 1 is annealed for two hours at 1100 deg.C under the N2 atmosphere and inter-lattice oxygen in the area near the rear surface is diffused to the external side, the area near the surface and rear surface becomes a fault-free layer. Next, when poly-Si 4 is adhered in the thickness of 1μm at 650 deg.C, oxygen precipitation core 5 is formed by the heat treatment of such process and precipitation of oxygen is accelerated. Thereafter, only the wafer surface is polished like a mirror surface, leaving the poly-Si layer 4 on the rear surface. Therefore, the area near the wafer surface becomes the fault-free layer due to the external diffusion and thereby the wafer having the EG effect by the poly-Si at the rear surface and IG effect due to increase in amount of oxygen precipitation can be obtained. As a result, a gate oxide film having high quality film can be obtained enough to improve the device characteristics.
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