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:
Jul. 16, 2002
Filed:
Jun. 05, 2001
Raffaele Zambrano, Viagrande, IT;
STMicroelectronics S.r.l., Agrate Brianza, IT;
Abstract
The ROM memory cell, not decodable by visual inspection comprises a substrate of semiconductor material having a first conductivity type, in particular P . A first MOS device having a first threshold voltage is formed in a first portion of the substrate, and a MOS device having a second threshold voltage, greater than the first threshold voltage, is formed in a second portion of the substrate adjacent to the first portion. The second MOS device is a diode reverse biased during a reading phase of the ROM memory cell and comprises a source region having the first conductivity type and a drain region having a second conductivity type. The source region has a level of doping higher than that of the substrate.