Method for manufacturing semiconductor device

Abstract

A method for manufacturing a semiconductor device which comprises the steps of forming a first groove in that portion of a semiconductor substrate where an isolation is to be formed; selectively forming a second groove narrower than the first groove in that surface region of the semiconductor substrate which is surrounded by said first groove; depositing a masking material over the whole surface of the semiconductor substrate with a thickness less than half the width of the first groove and greater than half the width of the second groove; aniotropically etching the deposited masking material to eliminate substantially its thickness, thus leaving the masking material on the side walls of the first groove and entirely in the second groove; introducing an impurity into the bottom of the first groove to form an impurity region; filling the first groove with an isolating material; and forming a semiconductor element in that section of the semiconductor substrate which is surrounded by an isolation consisting of the impurity region and the isolating material layer in the first groove. The semiconductor-manufacturing method of the invention forms an element isolation consisting of an isolating material filling the first groove and an impurity region, and also an interelement isolation region consisting of an isolating material filling the second groove which is narrower than the first groove, both isolations being formed with high precision.