| 摘要 |
PURPOSE:To virtually prevent a film rim from adverse influence by a method wherein the rim of a field insulating film is buried in a later process. CONSTITUTION:A groove 22 is formed in the field region of an Si substrate 21 and a channel stopper layer is formed on the side walls and bottom of the groove 22 by ion injection. An SiO2 film 23 is formed by CVD, to be buried in the groove 22 as a first insulating film. The SiO2 film 23 is formed at locations lower than superficial protrusions because of RIE etching. A second insulating film of SiO2 is deposited by CVD on the entire surface. Etching is performed, whereafter SiO2 film 24 is detained only on the side walls of the protrusions on the substrate 21. A gate oxide film 25 is formed, whereafter gate electrodes 261, 262 are built of polycrystalline Si. This design prevents the concentration of an electric field in the neighborhood of the protrusion on the substrate as well as the formation of parasitic channels, whereby the leak of current from an MOSFET may be reduced while its withstand voltage is heightened. |
