| 摘要 |
A method of forming an isolation trench structure wherein the dielectric material filling the trench extends beyond the trench edges thereby preventing gaps at the trench edges. A layer of first dielectric is formed on a silicon substrate and a layer of silicon, either polysilicon or amorphous silicon, or silicon nitride is formed on the layer of first dielectric. A resist mask having a trench opening is then formed on the layer of silicon or silicon nitride. An isotropic lateral etch, either a plasma isotropic lateral etch or a chemical wet etch, is then used to etch that part of said silicon or silicon nitride directly under the trench opening in the resist mask and to undercut the silicon or silicon nitride a first distance beyond the edge of the trench opening in the resist mask, thereby forming an oversize trench opening in the layer of silicon or silicon nitride. The trench opening is then transferred to the layer of first dielectric and a trench is formed in the silicon substrate. The resist mask is then removed and a layer of second dielectric is deposited. That part of the layer of second dielectric above the top surface of the layer of silicon or silicon nitride, the layer of silicon or silicon nitride, and the layer of first dielectric are then removed to complete the structure.
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