Isolation Structure Using Liquid Phase Oxide Deposition

摘要

A shallow trench isolation structure is formed by a process having a reduced number of steps and thermal budget by filling trenches by liquid phase deposition of an insulating semiconductor oxide and heat treating the deposit to form a layer of high quality thermal oxide at an interface between the deposited oxide and the body of semiconductor material (e.g. substrate) into which the trench extends. This process yields an isolation structure with reduced stress and reduced tendency to develop charge leakage. First, a trench (18) is formed in a silicon substrate (12) having a thin blanket layer (14) of a hard polish-stop material and a photo resist layer (16) (used to pattern the structure) formed thereon. A channel stop region (20) is formed as standard in the trench. Next, the trench is filled with SiO2 using liquid phase oxide deposition above the level of said thin layer. Then the photo resist layer is removed and the SiO2 fill (22) is planarized. Finally, the SiO2 fill is densified and during the thermal cycle, a thin layer (30) of thermal oxide is formed at the fill-substrate interface. The structure can be readily and easily planarized, and voids contamination of the deposited oxide are substantially eliminated by self-aligned deposition above the trench in the volume of apertures on the resist used to form the trench.