METHOD OF FORMING POLYSILICON IN A TRENCH
First Claim
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1. A method for forming polysilicon in a trench, comprising:
- providing a substrate;
forming a first dielectric layer on said substrate;
forming an opening in said first dielectric layer by etching;
forming a trench in said substrate by etching through said opening;
forming a second dielectric layer on sidewalls of said trench;
forming polysilicon on a surface of said substrate and on a surface of said second dielectric layer in said trench;
applying a sacrificial layer on a surface of polysilicon; and
removing said sacrificial layer and the portion of polysilicon on said surface of said substrate successively by etching, while the portion of polysilicon remaining in said trench is etched to a predetermined depth below said surface of said substrate.
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Abstract
Disclosed herein are methods for forming polysilicon in a trench. The sacrificial layer having a high etching rate is applied on the surface of polysilicon after polysilicon is formed on the surface of the substrate and in the trench. The sacrificial layer can provide a flat surface. With the sacrificial layer as a sacrificial mask layer, polysilicon can be etched as having a flat surface. The present disclosure avoids using the CMP process, simplifies the manufacturing process, and reduces the production cost. Moreover, the oxide layer formed thereafter can meet the requirement of current applications.
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Citations
10 Claims
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1. A method for forming polysilicon in a trench, comprising:
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providing a substrate; forming a first dielectric layer on said substrate; forming an opening in said first dielectric layer by etching; forming a trench in said substrate by etching through said opening; forming a second dielectric layer on sidewalls of said trench; forming polysilicon on a surface of said substrate and on a surface of said second dielectric layer in said trench; applying a sacrificial layer on a surface of polysilicon; and removing said sacrificial layer and the portion of polysilicon on said surface of said substrate successively by etching, while the portion of polysilicon remaining in said trench is etched to a predetermined depth below said surface of said substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification