| 摘要 |
To form substrate isolation for a nonvolatile memory, floating gate polysilicon (410) is formed over a semiconductor substrate (110), then silicon nitride (130) is deposited, and then the nitride, the floating gate polysilicon and the substrate are etched to form isolation trenches (140). Dielectric (150) is formed in the trenches and over the silicon nitride. The dielectric thickness is relatively small so that the top surface (150T) of the dielectric over the trenches lies at all times below the top surface of silicon nitride. The dielectric deposition and polishing times are therefore reduced. Other embodiments are also provided.
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