Misalignment Study by Etch Induced Silicon Damage in Single Crystal Etch process for Shallow Trench Isolation Structure

We studied the misalignment between active and gate layer in terms of silicon dislocation caused by high temperature anneal process in SOG based STI gap-fill process. The SOG process is one of good candidates to overcome gap-fill limitation due to its excellent gap-fill characteristics. However, the SOG process needs high temperature anneal process to convert from Si-H, N-H to Si-O bond, which leads to the misalignment due to large stress change. We suggest that silicon defect is generated from ion bombardment at trench etch process and accelerated from hysteresis at anneal process. The O-2 cure process is known as one of feasible methods to cure silicon damage through recrystallization. Based on this model, the misalignment was significantly improved as removing the defect through O-2 cure process following trench etch process.