| 摘要 |
A high-resistance substrate with good RF characteristics, which has an interstitial oxygen concentration (ÄOiÜ) of 8E17 cm<-3> or less, an oxygen precipitate density (ÄBMDÜ) of 1E8 cm<-3> or more, and a substrate resistivity of 500 OMEGA .cm or more is used. A heat-treating step of the device process is performed for 25 hrs or less as a value calculated assuming that the temperature is 1,000 DEG C. This suppresses a decrease in the resistance of the substrate, prevents crystal defects such as slip, and improves the yield. <IMAGE> |
