Method of forming a shallow trench isolation region

摘要

A method of making a shallow trench isolation region includes providing a silicon substrate. A pad oxide layer is formed over the silicon substrate. A silicon nitride layer is formed over the pad oxide layer. The silicon nitride layer and the pad oxide layer are patterned, and a trench is thus formed in the silicon substrate. A side-wall oxide layer is formed on a surface of the silicon substrate within the trench. A doped oxide layer is formed over the silicon nitride layer and within the trench. A portion of the doped oxide layer is removed to expose the silicon nitride layer. The silicon nitride layer is removed. The pad oxide layer is removed. A sacrificial oxide layer is formed over the silicon substrate. A well is formed in the silicon substrate. The sacrificial oxide layer is removed. A gate oxide layer is formed over the silicon substrate. A polysilicon layer is formed over the silicon substrate. The polysilicon layer is patterned to form a polysilicon gate.