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US 7,115,934 B2Granted
Method and structure for enhancing trench capacitance
AssigneeInternational Business Machines Corporation
InventorsKangguo Cheng, Ramachandra Divakaruni
Life of this patent
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Abstract
A trench capacitor formed with a bottle etch step has a polygonal cross section produced by forming thermally oxidizing the trench walls with thinner oxide at the corners of the trench, then performing the bottle etch step with the nitride in place, thereby extending the trench walls laterally only outside the corners, so that the distance of closest approach between adjacent trenches is reduced while the length of the perimeter is maintained.
Claims3
A trench structure formed in a semiconductor substrate comprising:
- an upper portion of said trench having an upper polygonal cross section;
- a lower portion of said trench having a lower polygonal cross section comprising four straight main sides oriented with an angular difference between consecutive main sides;
- four inner projecting corners disposed between said four main sides, said four inner corners being located closer to a center of said polygonal cross section than said main sides;
- connecting lines connecting said inner corners with said main sides;
- and said lower polygonal cross section having a greater number of sides than said upper polygonal cross section.
2 more elements
A capacitor formed in a trench in a semiconductor substrate comprising:
- an upper portion of said trench having an upper polygonal cross section;
- a lower portion of said trench having a lower polygonal cross section comprising four straight main sides oriented with an angular difference between consecutive main sides;
- four inner projecting corners disposed between said four main sides, said four inner corners being located closer to a center of said polygonal cross section than said main sides;
- and connecting lines connecting said inner corners with said main sides;
- said lower polygonal cross section having a greater number of sides than said upper polygonal cross section;
- a node dielectric disposed on interior surfaces of said lower portion of said trench;
- and a conductive center electrode disposed within said trench and abutting said node dielectric.
4 more elements
Dependencies are inferred from the claim text.