METHOD FOR MANUFACTURING A SEMICONDUCTOR DEVICE

摘要

A method for fabricating a semiconductor device is provided to maximumly overcome short channel effect of a transistor with a general recess gate by forming a transistor with a bulb-type recess gate having a longer channel than that of a transistor with a conventional recess gate. A substrate(10) having a trench with a predetermined depth is prepared. A spacer oxide layer(13a) is formed along the step of the upper part of the substrate having the trench. The spacer oxide layer is partially etched in a manner that the spacer oxide layer is left on the sidewall of the trench and the substrate on the bottom of the trench is exposed. The substrate exposed by an etch process using the spacer oxide layer as a barrier layer is etched by a predetermined depth to form a bulb-type trench(15) in the lower part of the trench. The spacer oxide layer is etched. The spacer oxide layer is formed by a plasma oxide process, having a greater thickness at the sidewall of the trench than that at the bottom of the trench.