| 摘要 |
PURPOSE: A method for manufacturing a semiconductor device is provided to improve a characteristic by making a step difference of a first gate better. CONSTITUTION: A method for manufacturing a semiconductor device comprises the steps of: forming a buffer oxidation layer and a nitride layer on a semiconductor substrate, etching a part of the buffer oxidation layer and the nitride layer through a photolithography, and forming a trench by etching the semiconductor substrate to a constant depth; filling up the trench for planarization, and protruding the oxidation layer filled up in the trench by eliminating the nitride layer and buffer oxidation layer out of the surface of the semiconductor substrate; forming an insulation layer on the entire structure, and forming a sidewall of the oxidation layer much protruded than the surface of the semiconductor substrate by selectively etching the insulation layer; forming a gate oxidation layer on the semiconductor substrate, evaporating a lower conductive layer on the gate oxidation layer and oxidation layer, and planarizing to expose the oxidation layer; forming a upper conductive layer and a cap insulation layer on the lower conductive layer and exposed oxidation layer; and patterning the cap insulation layer, the upper conductive layer through a photolithography process using a first gate mask, the lower conductive layer and the gate oxidation layer, and forming a first gate having a stack of a gate oxidation layer, a lower conductive layer, a upper conductive layer and a cap insulation layer on the semiconductor substrate while a first gate having a stack of a upper conductive layer and a cap insulation layer is separately formed on an oxidation layer.
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