| 摘要 |
PURPOSE:To obtain a substrate having many crystal defects at inside and less crystal defects around the surface, and to obtain an appropriate substrate in compliance with the use by a method wherein a heat treatment respectively specified the heat treatment temperature is performed at three times on the silicon substrate to rise and all the generated nucleus of crystal defects. CONSTITUTION:The silicon substrate 1 is heat treated at the temperature of 600- 900 deg.C, at first, make generate the generating nucleus 2 of the crystal defects mainly composed of the oxygen atoms, the treatment time is selected as 18hr if it is 650 deg.C, and about 4hr if 800 deg.C. At this time, the substrate 1 is made by the crystal pulling method the first process can be ommited. Next thereto, as the second process it is heat treated at 1,100-1,300 deg.C to diffuse the oxygen atoms around the surface to the outside, and make generate the region 4 having less generating nucleus of crystal defects around the surface, then it is heat treated at 900-1,100 deg.C as the third process, the generating necleus is made produced at the inside to form a laminate defects 3. Thus the desired P-N junction is formed in the region 4 and to get out the metal impurity by the defects 3 which does not attribute to the conductive type. |
