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:
Nov. 16, 1999
Filed:
Dec. 23, 1997
Giovanna Dalla Libera, Monza, IT;
Bruno Vajana, Bergamo, IT;
Roberta Bottini, Lissone, IT;
Carlo Cremonesi, Vaprio D'Adda, IT;
SGS-Thomson Microelectronics S.r.l., Agrate Brianza, IT;
Abstract
A process for fabricating a memory cell having two levels of polysilicon and being included in a memory device of the EEPROM type, wherein the device is formed on a semiconductor material substrate which has a first conductivity type. The process comprises the steps of forming, on the substrate a thin tunnel oxide region surrounded by a gate oxide region previously formed on the same substrate, depositing a layer of polycrystalline silicon over the gate oxide region and the thin tunnel oxide region, and successively depositing a composite ONO layer and an additional polysilicon layer over the polycrystalline silicon layer. A capacitive implant mask having a window is formed by depositing a layer of a light-sensitive material over the additional polysilicon layer, a dopant is implanted through the window at an energy and with dosages effective to penetrate the polycrystalline silicon, ONO, and polysilicon layers, respectively, and a region of electric continuity is formed laterally and beneath the thin tunnel oxide region.