| 摘要 |
PURPOSE:To remove undesired As diffusion by a method wherein after As ions are injected, the insulating film surface is etched and subsequently a heat treatment is applied thereto. CONSTITUTION:Into a P type Si substrate 1, B ions are injected 2 by using an Si3N4 mask 8 and wet-oxidized to form a field oxide film 3. Then, the mask 8 is removed, and a gate oxide film 4 and a polycrystalline Si gate electrode 5 are formed. After As ions have been injected thereinto, this is dipped in an HF solution to selectively etch the surface layer of the ion-injected SiO2. The polycrystalline Si layer 5 and the Si substrate 1 are not etched. Then, this is treated in N2 at approximately 1,000 deg.C to recover the crystal lattice, and N layers 6 and 7 are provided. By said constitution, because As in the field oxide film has been removed, there is no possibility that As invades the channel cut layer 2 in the high-temperature treatment, resulting in lowering in concentration or inversion. Accordingly, reliability of the device improves. |
