TRENCH ISOLATION STRUCTURE AND FABRICATING METHOD THEREOF

摘要

PURPOSE: A method for fabricating a trench isolation structure is provided to prevent a dishing phenomenon in a planarization etch process and to improve a characteristic of an isolation layer, by forming the isolation layer through three processes for forming buried layer and two planarization etch processes. CONSTITUTION: The first trench(206a) and the second trench(206b) having a with broader than that of the first trench are formed on a semiconductor substrate(200). The first buried layer(210) filling the first trench is formed on the resultant structure having the first and second trenches. The second buried layer filling the second trench is formed on the first buried layer. The second buried layer is planarization-etched until the first buried layer is exposed. The first buried layer is etched to make the upper surface of the first buried layer lower than the upper surface of the semiconductor substrate so that a recess portion is formed. The third buried layer(215) filling the recess portion is formed on the resultant structure having the recess portion. The third and second buried layers are planarization-etched to form the isolation layer(220a,220b) filling the first and second trenches.