METHOD FOR FORMING ISOLATION LAYER OF SEMICONDUCTOR DEVICE TO PREVENT DIVOT FROM BEING FORMED IN ISOLATION LAYER

摘要

PURPOSE: A method for forming an isolation layer of a semiconductor device is provided to prevent a divot from being formed in an isolation layer by growing silicon on a silicon substrate by an SEG(selective epitaxial growth) method and by performing a thermal oxide process on the selectively grown silicon. CONSTITUTION: The first oxide layer and the first nitride layer that are sequentially deposited on a silicon substrate(21) are patterned to be a predetermined shape. A part of the first oxide layer adjacent to the lower edge of the first nitride layer is laterally etched. A silicon layer is deposited on the substrate exposed through the first nitride layer pattern. The silicon layer is grown by a SEG method to form an SEG-Si layer capable of burying a space formed by laterally etching a part of the first oxide layer. The SEG-Si layer is transformed by a thermal oxide process to form a thermal oxide layer. The thermal oxide layer and the substrate are removed by an etch process using the first nitride layer pattern as an etch mask to form a trench in the substrate wherein a part of the thermal oxide layer under the first nitride layer is not eliminated. An insulation material having such a sufficient thickness to bury the trench is deposited and a planarization process is performed to form an isolation layer(26). The first nitride layer and the first oxide layer remaining on the substrate are eliminated.