METHOD FOR FORMING MASK ALIGNMENT KEY OF SEMICONDUCTOR DEVICE

摘要

PURPOSE: A method for forming a mask alignment key of a semiconductor device is provided to reduce a manufacturing cost by decreasing the number of mask. CONSTITUTION: A pad oxide layer(2) and a nitride layer(3) are deposited on a substrate(1). A photoresist(PR) is applied on the nitride layer(3). The photoresist(PR) is exposed by using a mask having a half-permeation region and a shield region. A part of the nitride layer(3) is exposed and a photoresist pattern is formed by developing the photoresist(PR). An etching process is performed by using the photoresist pattern as a mask. The photoresist pattern is removed. An oxide layer is deposited thereon. A shallow trench isolation structure is formed by removing the nitride layer(3) and the pad oxide layer(2). A mask alignment key is formed on a deep trench.