The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 22, 2002
Filed:
Dec. 17, 1999
Sundar K. Iyer, Beacon, NY (US);
Rama Divakaruni, Middletown, NY (US);
Herbert L. Ho, New Windsor, NY (US);
Subramanian Iyer, Mount Kisco, NY (US);
Babar A. Khan, Ossining, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method of connecting a trench capacitor in a dynamic random access memory (DRAM) cell. First, trenches are formed in a silicon substrate using a masking layer including a pad nitride layer on a pad oxide layer. Trench capacitors are formed in the trenches. A buried strap is formed in each trench on the capacitor. The nitride pad layer is pulled back from the trench openings, exposing the pad oxide layer and any strap material that may have replaced the pad oxide layer around the trenches. The straps and trench sidewalls are doped to form a resistive connection. During a subsequent shallow trench isolation (STI) process, which involves an oxidation step, the exposed strap material on the surface of the silicon surface layer forms oxide unrestrained by pad nitride without stressing the silicon substrate.