The Pre-CMP Oxide Deposition step follows the initial conformal shallow trench isolation (STI) fill and its subsequent anneal P1.While the preceding conformal layer protects the trench interfaces and ensures high-quality dielectric contact, it leaves non-planar topography and potential central seams within the trench A3.The "Pre-CMP Oxide Deposition" applies a bulk dielectric layer, often referred to as the overburden, which is essential to provide sufficient material thickness for the subsequen