to 1 4 u00d7 10 18 atoms cm 3 old astm so as to generate oxygen precipitation nuclei higher than a desired density by the heat treatment of the third embodiment the heat treatment of the third embodiment is rapid heating and is conducted by heating the wafer w 3 in an atmosphere of nitrogen argon hydrogen or oxygen or mixture thereof from a room temperature up to temperatures of 1 150 u00b0 c to 1 200 u00b0 c at a temperature elevating speed of 10 u00b0 c second to 150 u00b0 c second and hold the wafer w 3 at temperatures of 1 150 u00b0 c to 1 200 u00b0 c for 0 to 30 seconds tht is the heat treatment performed in the third embodiment is the type a rapid heating herein a holding time of 0 second means that only temperature elevation is conducted and holding is not conducted heating is conducted by introducing the wafer into a heat treatment furnace held at a room temperature or into the interior of a heat treatment furnace held at a temperature of several hundreds degrees by residual heat in case of a continuous operation and temperature elevated to temperatures of.