METHOD FOR FORMATION OF DEVICE ISOLATION LAYER USING MULTILAYER MASK

摘要

PURPOSE: A method for formation of a device isolation layer using a multilayer mask is provided to improve the characteristics of the device by obtaining the height of uniform element isolation film without interference of the density of pattern. CONSTITUTION: A pad oxide film(21), a first mask film, a first mask, interlay oxide film, and mask laminated pattern of a second mask film are formed on a semiconductor substrate. A trench is formed within the semiconductor substrate by etching the semiconductor substrate with a mask laminated pattern is used as a mask. An element isolation layer(30) is formed at the front of the semiconductor substrate in which the trench is formed. A first CMP (chemical mechanical polishing) process of the element isolation layer is performed not to expose the second mask film to the outside. One part of the element isolation layer is etched so that the second mask film is exposed. The second mask film is selectively removed so that the element isolation layer is protruded from the semiconductor substrate. A second CMP process of the element isolation layer is performed by using a second mask film as a CMP stopper film. The second mask film is removed after the second CMP.