JP2506830B

PURPOSE:To facilitate the setting of impurity concentration and the prediction of characteristics by uniformly introducing impurity to determine transistor characteristics into a part of side wall surface of a trench formed in a semiconductor, which part turns to a channel, by a means such as oblique ion implantation from the side wall surface. CONSTITUTION:A deep trench is formed on a substrate composed of P-type silicon 1 of high concentration and a P-type epitaxial layer 2. A storage capacitor part is formed in the inside of the trench, by using polycrystalline silicon electrode 4 to store electric charge and an SiO2 film 3. Further, an N-type layer 5 and a buried contact layer 6 turning to the source.drain of a vertical type transistor are formed. The inside of the trench is oxidized, and an SiO2 film 11 is grown on the side wall surface at which a channel 9 of the transistor is positioned. Boron ion 12 to determine transistor characteristics is ion- implanted obliquely to a channel regin 9, through the SiO2 film 11 from a trench aperture part. By this implantation, an impurity layer of uniform concentration is introduced in the region 9. Thereby a structure which is not different from usual transistors is realized in spite of a vertical type transistor.