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Process of Removing Reliability a-Si Cap for RMG stack for 7n, and Beyond.

IP.com Disclosure Number: IPCOM000250218D
Publication Date: 2017-Jun-12
Document File: 1 page(s) / 31K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to remove amorphous Silicon (a-Si) in narrow spaces for the Replacement Metal Gate (RMG) stack for 7 nm and beyond. This method is a combination of a dry isotropic etch and a wet removal process comprising a basic chemistry. This method cleanly removes Si that remains after dry etch using basic chemistry without diluted HF (DHF) breakthrough.

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Title Process of Removing Reliability a-Si Cap for RMG Stack for 7 nm and Beyond Abstract Disclosed is a method to remove amorphous Silicon (a-Si) in narrow spaces for the Replacement Metal Gate (RMG) stack for 7 nm and beyond. This method is a combination of a dry isotropic etch and a wet removal process comprising a basic chemistry. This method cleanly removes Si that remains after dry etch using basic chemistry without diluted HF (DHF) breakthrough. Problem Replacement Metal Gate (RMG) flow is a series of depositions and etches/ removals. Historically, removal is not an issue. Wet etch always had full access to do a thin film removal because the earlier nodes have sufficient spaces for wet etch to access. In 7nm, due to aggressive shrink, some of the depositions are plugging/pinching critical pinch points (e.g., charge trapping (CT) to fin and extended gate (EG) oxide space. Solution/Novel Contribution The novel contribution is a method to remove amorphous Silicon (a-Si), selective to SiO2, HK dielectric, and/or metal, in narrow spaces for the RMG stack for 7 nm and beyond. This method is a combination of a dry isotropic etch (i.e., dry Fluorine based chemistry to remove bulk of the silicon) and a wet removal process comprising a basic chemistry (i.e., NH4OH, TEAH and TMAH, Peroxide). The wet etch follows the dry isotropic etch. Si removal requires a diluted HF (DHF) breakthrough to remove the native oxide before the basic wet etch chemistry. The novel solution presented...