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Nitrogen Incorporation in Inter-Poly Dielectric and Gate Oxide For Improved NVM and Logic Reliability

IP.com Disclosure Number: IPCOM000005724D
Original Publication Date: 2001-Oct-30
Included in the Prior Art Database: 2001-Oct-30
Document File: 3 page(s) / 49K

Publishing Venue

Motorola

Related People

Zhixu Zhou1: AUTHOR [+3]

Abstract

Nitrogen Incorporation in Inter-Poly Dielectric and Gate Oxide For Improved NVM and Logic Reliability

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Nitrogen Incorporation in Inter-Poly Dielectric and Gate Oxide

For Improved NVM and Logic Reliability

Zhixu Zhou1, Wayne Paulson2, James Heddleson3

1.      Design and Platform, WSSG,  2.  NVMTC, TSG, 3.  AMIDL, DDL

We propose and demonstrate a process integration that incorporates nitrogen into the inter-poly dielectric for non-volatile memory (NVM), and, simultaneously into peripheral high voltage gate oxides and low voltage logic gate oxides. This proposed nitridation technique provides process flexibility to incorporate nitrogen into different dielectric films in an embedded NVM memory array within a CMOS flow.  Enhanced NVM and logic reliability is achieved using the proposed nitridation technique.

                    Figure 1. shows the cross section of a split gate flash bit cell with an adjacent high voltage gate oxide.  A typical sequence for a split gate flash process is described as follows: (1). Front end isolation and well formation, (2) coupling oxide followed by poly1 and nitride depositions,  (3) floating gate poly1 mask and nitride etch, (4) poly1 oxidation to form poly1 injector for NVM erase operation, (5) poly1 hard mask etch,  (6) simultaneous inter-poly dielectric and HV gate oxide formation,  (7) LV gate oxide formation,  (8) N2O or NO anneal, or an NH3 anneal followed by thermal anneal, or a N implantation or a plasma exposure to a N containing ambient to introduce nitrogen into inter-poly oxide and at interfaces between poly1& poly2/oxides.  The nitridation step may also be performed after Poly2 deposition along with an anneal to drive the nitrogen into the dielectrics.

            The proposed integration is able to introduce nitrogen simultaneously into inter-poly dielectric material, as well as high voltage transistor oxide and LV logic gate oxides. Nitrogen incorporation strengthens bond structures and reduces charge trapping rates under high field stress, which improves NVM cycling endurance and gate oxide reliability simultaneou...