| 摘要 |
PURPOSE:To flatten the surface of a single crystal silicon layer forming an SOI substrate and to prevent inclusion of a grain boundary into the single crystal silicon layer, by removing an ion implanting mask 41, projecting argon laser in a scanning mode, and converting a polycrystalline silicon layer on the upper part of a silicon dioxide layer into the single crystal silicon layer. CONSTITUTION:A silicon dioxide layer 6 is formed in a region, which is not masked with an ion implanting mask 41, in a polycrystalline silicon layer 3. After the mask 41 is removed, a silicon substrate is kept at the state the substrate is heated to about 500 deg.C. Continuous wave argon laser of 8-10W is at a speed of 15 cm/sec. The polycrystalline silicon layer 3 at a region of a thickness of about 0.2mum at the upper part of the silicon dioxide layer 6 is converted into a single crystal silicon layer 7. The polycrystalline silicon layer 3 undergoes mesa etching, and an SOI substrate 31 comprising the single crystalline silicon layer 7 and the silicon dioxide layer 6 is formed. A gate insulating film 8 and a gate electrode 9 are formed. With the gate electrode 9 as a mask, n-type impurity ions are implanted, and a source 10 and a drain 11 are formed. Thus a MOS field effect transistor is formed. |
