| 摘要 |
PURPOSE:To form a P-N junction without diffusing an impurity at a high temperature, and to prevent the possibility of the mixing of a noxious impurity by outward diffusing oxygen in the whole surface or a partial region of a P type semiconductor through heat treatment at a high temperature and thermally treating the semiconductor at a low temperature of a specific value. CONSTITUTION:A P type silicon wafer 11 in oxygen concentration of a value such as 1.5X10<18>cm<-3> or less is prepared. Oxygen in the silicon wafer 11 is diffused outward through heat treatment at a high temperature such as 1,000 deg.C or higher. Consequently, the concentration of oxygen in surface regions 12, 13 on both surfaces of the silicon wafer 11 lowers. New-doners are generated through heat treatment at 550-900 deg.C such as a temperature close to 650 deg.C for a prolonged time. The generation of the new-doners reduces in the wafer surface regions 12, 13, from which oxygen is diffused outward, and increases in an internal region 14 because it mutually relates to oxygen concentration. As a result, the wafer internal region 14 is changed into an I type from a P type and further into an N type through heat treatment for a prolonged time. Accordingly, a P-N junction is formed. |
