ROBUST SHALLOW TRENCH ISOLATION STRUCTURES AND A METHOD FOR FORMING SHALLOW TRENCH ISOLATION STRUCTURES

摘要

A robust and shallow trench isolation structure is provided to fabricate an STI structure without a void by eliminating arbitrary process effect capable of causing formation of voids. An opening is formed in a semiconductor layer. A dielectric material(56) is deposited in the opening. A conformal material is deposited on the dielectric material. The conformal material is removed. The process for depositing the dielectric material in the opening includes the following steps. A silicon dioxide liner adjacent to the sidewalls of the opening is deposited. A low-density USG(undoped silicon glass) is deposited near the liner. High-density USG is deposited in the rest of the opening. The voids are formed near the interface between the low-density and high-density USG materials.