| 摘要 |
PURPOSE:To form a MOS FET whose Vth value is stable by a method wherein a gate electrode and an X-ray shieding plate are formed in succession to formation of a gate oxide film so that the gate insulating film cannot be damaged by a subsequent X-ray lithographic operation. CONSTITUTION:First, a positive-type X-ray resist 7 is coated on a p-Si substrate 1; X-rays are irradiated selectively by using a mask 8; a groove 9 is made by a dry etching method. The resist is removed; a gate oxide film 3 by thermal oxidation is formed; a poly-Si layer 4 to be used as a gate electrode is deposited by using a deposition method with good covering performance such as a lowpressure CVD method. In succession, a W layer 5 to be used as an X-ray shielding sheet is applied by using an MOCVD method or a sputtering operation; excess W is etched and removed by a treatment method such as a bias sputtering method; an S/D region 2 is formed by ion implantation. A cover film 10 as PSG is covered; an Al electrode 11 is formed; as a result, a MOS FET is obtained. |
