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Etchants and Etching Processes for High k Gate Dielectric

IP.com Disclosure Number: IPCOM000009058D
Original Publication Date: 2002-Aug-05
Included in the Prior Art Database: 2002-Aug-05
Document File: 4 page(s) / 172K

Publishing Venue

Motorola

Related People

Xiaoping Wang: AUTHOR [+3]

Abstract

Integration of high k gate dielectric materials into a standard CMOS flow requires that a wet etching approach be developed to avoid plasma damage during a dry etch.

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Etchants and Etching Processes for High k Gate Dielectric

Xiaoping Wang, Hongwei Zhou, Bich-Yen Nguyen

Abstract

    Integration of high k gate dielectric materials into a standard CMOS flow requires that a wet etching approach be developed to avoid plasma damage during a dry etch.  The etchants and etching processes for two kinds of high k gate dielectric materials, lanthanum aluminate and lanthanum aluminum oxynitride, are proposed.  In the proposed method, the mixed solution of hydrochloric acid/phosphoric acid with deionized water and/or hydro peroxide can effectively remove lanthanum aluminate and lanthanum aluminum oxynitride films at high etch rates up to 5nm/min. The films can be completely removed resulting in a very smooth surface. The proposed technique can be used in fabrication flows where lanthanum aluminate and lanthanum aluminum oxynitride are used as high k gate dielectrics for logic, memory, and analog products.

Problem and its solution

     Although high-k gate dielectrics may offer some advantages over SiO2, integration of these materials into a standard CMOS flow remains a challenge. For instance, the knock-on of metal into the source/drain regions may warrant the removal of the high-k film before ion implantation, and silicidation of the source/drain regions requires the removal of the high-k film.  A wet chemistry to etch high-k gate dielectrics would be advantageous to avoid plasma damage during a dry etch. Therefore, the wet etching behavior of high-k gate dielectrics needs to be addressed [1]. Among the various high k gate dielectric materials, Lanthanum aluminate and lanthanum aluminum oxynitride materials are being investigated as promising candidates to take advantage of the high dielectric constant of binary metal oxides combined with high thermal stability.

    According to our disclosure, the etchant reagents to wet etch these two kinds of materials are effective, and the etching processes are easy to handle. The etching solutions are mixed solution of hydrochloric acid with deionized water in various volume ratios, or mixed solution of hydrochloric acid with hydro peroxide and deionized water in various volume ratios, or mixed solution of hydrochloric...