MANUFACTURE OF SEMICONDUCTOR DEVICE

PURPOSE:To prevent ion damage by forming a trench by projecting an ion beam, burying positive resist in the trench to flatten the surface, performing etching by using a resist pattern as a mask, and forming a T-type dummy pattern. CONSTITUTION:By projecting Ga ion beam 6 on an insulating film 5, a trench 7 is formed, in which positive resist 9 is buried. By etching a film 5 by using the resist 9 as a mask, a residual pattern 10 is formed, and electron beam resist 11 is spread on the whole surface. By etching the resist 11, the head of the resist 9 is exposed, the buried resist 9 is eliminated with developer, and then the pattern 10 is eliminated with etching liquid. After that, a gate electrode metal film 12 is deposited by a vapor-deposition method. and finally an unnecessary metal film 12 is eliminated by lift-off method, thereby completing a T-type gate electrode 13. Hence a microstructural gate electrode can be stably formed, and the performance of a FET can be improved.