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:
Sep. 14, 2004
Filed:
Nov. 01, 1999
Seiko Epson Corporation, Tokyo, JP;
Abstract
A semiconductor memory device has a peripheral circuit area and a memory cell area on a main surface thereof. The semiconductor memory device includes a first well formed in the peripheral circuit area, a second well of a first conductivity type formed in the memory cell area, a third well of a second conductivity type formed in the memory cell area, and a device isolation structure formed in the memory cell area for isolating an element formed in the second well from an element formed in the third well. The second well of the first conductivity type has a depth shallower than a depth of the first well. The third well of the second conductivity type is equal in depth to the second well. The second and third wells are formed down to a level lower than the device isolation structure.