SEMICONDUCTOR ELEMENT ISOLATION METHOD

摘要

PURPOSE: A method for fabricating a semiconductor device is to prevent a device region from being decreased by the bird's beak in forming a field oxide layer. CONSTITUTION: A hard mask layer is formed on a predetermined part of the semiconductor substrate(21) to define an active region(a2) and a field region(f2). A groove is formed in the semiconductor substrate by using the hard mask layer as a mask. After removing the hard mask layer, the first and second anti-oxidation layers are formed on the semiconductor substrate including the surface of the groove. Then, the first and second anti-oxidation layers are patterned by a photolithography method to expose the bottom of the groove. A field oxide layer(29) is formed by thermally oxidizing the exposed bottom of the groove. The field oxide layer is grown in the lateral direction by diffusing oxygen into the semiconductor substrate through the interface between the groove and the first and second anti-oxidation layers.