METHOD FOR FORMING TRENCH OXIDE LAYER OF SEMICONDUCTOR DEVICE

摘要

PURPOSE: A method for forming a trench oxide layer of a semiconductor device is provided to bury a trench without a void, by forming an oxide layer for burying the trench, by performing a CMP(chemical mechanical polishing) process and by performing a dry etch process and a wet etch process so as to form a groove in the oxide wherein the width of the groove increases as it goes from the lower portion to the upper portion while the void is exposed by the CMP process. CONSTITUTION: A silicon nitride is formed on a semiconductor substrate(11). The silicon nitride layer and a predetermined thickness of the substrate are selectively etched to form a trench in the substrate. The first oxide layer(16) is deposited on the resultant structure including the trench to bury the trench. The first CMP process is performed until the silicon nitride layer is exposed, so as to expose the void during a process for depositing the first oxide layer. The first oxide layer including the exposed void is dry-etched and wet-etched to broaden the region of the void so that a groove is formed in the first oxide layer wherein the width of the groove broadens as it goes from the lower portion to the upper portion. The second oxide layer(17) is formed on the first oxide layer to fill the trench. The second CMP process is performed on the second and first oxide layers until the silicon nitride layer is exposed.