| 摘要 |
PURPOSE:To improve the percentage of non-defective elements, by irradiating the rear face of a semiconductor substrate whose surface carries elements with excimer laser in the gaseous atmosphere containing nitrogen or oxygen for coupling excited silicon atoms with nitrogen or oxygen elements. CONSTITUTION:The rear face of an Si substrate which has been cut out of an ingot and polished roughly is irradiated with excimer laser 2 at a laser energy density of 5J/cm<3> in the atmosphere of N2 gas, while the surface thereof is mirror polished to obtain a semiconductor substrate 3. The rear face of the substrate 3 thus obtained has damages 4 with a depth of as large as 1-5 mum. The substrate will suffer from similar damages if it is treated within O2. An Si oxide is produced within the O2 whereas an Si nitride is produced within N2, The substrate 3 is then heat treated at 1150 deg.C for two hours, whereby the layer defect density becomes 10<5>-10<6>/cm<3> in case of N2 treatment while it becomes about 10<4>/cm<3> in case of O2 treat ment. In either case, these elements are coupled with Si atoms and fixed in the vicinity of the surface layer. Thus, the percentage of non-defective semiconductor elements can be improved.
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