Semiconductor structure for preventing row hammering issue in DRAM cell and method for manufacturing the same
First Claim
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1. A semiconductor structure for preventing row hammering issue in DRAM cell, comprising:
- a substrate;
a plurality of trenches comprising a first trench and a second trench, wherein said first trench is deeper than said second trench;
a shallow trench isolation comprising an upper portion and a lower portion disposed in said first trench, wherein said upper portion is disposed on said lower portion and has a different material composition from said lower portion, and said lower portion directly contacts and covers around entire perimeter surface of said first trench, and said upper portion has a top surface being higher than a bottom surface of said second trench, and a thickness of said lower portion is thicker at bottom than at sidewalls thereof, and said top surface of said upper portion of said shallow trench isolation has a convexly-curved shape;
a gate dielectric conformally on said second trench and conformally on said lower portion and said upper portion of said shallow trench isolation in said first trench;
an n-type work function metal layer conformally on and directly contacting said gate dielectric;
a titanium nitride layer conformally on said n-type work function metal layer; and
a buried word line on said titanium nitride layer in said trenches, wherein an entire top surface of said buried word line is flat.
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Abstract
A semiconductor structure for preventing row hammering issue in DRAM cell is provided in the present invention. The structure includes a trench with a gate dielectric, an n-type work function metal layer, a TiN layer conformally formed within, and a buried word line filled in the trench.
19 Citations
6 Claims
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1. A semiconductor structure for preventing row hammering issue in DRAM cell, comprising:
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a substrate; a plurality of trenches comprising a first trench and a second trench, wherein said first trench is deeper than said second trench; a shallow trench isolation comprising an upper portion and a lower portion disposed in said first trench, wherein said upper portion is disposed on said lower portion and has a different material composition from said lower portion, and said lower portion directly contacts and covers around entire perimeter surface of said first trench, and said upper portion has a top surface being higher than a bottom surface of said second trench, and a thickness of said lower portion is thicker at bottom than at sidewalls thereof, and said top surface of said upper portion of said shallow trench isolation has a convexly-curved shape; a gate dielectric conformally on said second trench and conformally on said lower portion and said upper portion of said shallow trench isolation in said first trench; an n-type work function metal layer conformally on and directly contacting said gate dielectric; a titanium nitride layer conformally on said n-type work function metal layer; and a buried word line on said titanium nitride layer in said trenches, wherein an entire top surface of said buried word line is flat. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification