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Reduced Si Recess for FIN Cut Step with Wet Removal

IP.com Disclosure Number: IPCOM000248747D
Publication Date: 2017-Jan-05
Document File: 2 page(s) / 283K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to reduce Silicon (Si) recess for FIN cut step using wet removal of Oxide and Nitride with high selectivity against Si.

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This is the abbreviated version, containing approximately 100% of the total text.

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Reduced Si Recess for FIN Cut Step with Wet Removal

FIN formation is required to cut/remove extra fin to define the final device. FINs are created using a “SEA of FIN” by different techniques. There are two ways to remove the extra FIN:

• Before the FIN – silicon Etch called Cut first

• After the FIN silicon Etch – called Etch last

For the FIN Cut first, the goal is to achieve a minimal recess of the Silicon (Si). Wet clean hardmask (HM) removal is offering a greater selectivity with an expected < 1nm recess.

This disclosure addresses the core elements of reducing recess of the poly, while removing the extra FIN with the usage of more selective chemistry while the silicon is still protected by the Optical Planarizing Layer (OPL). HF wet-base chemistry could remove Oxide and Nitride with high selectivity against Si. Top Siarc can be removed either by Etch (at the end of OPL partial open) or by wet methods.

Figure 1: Illustration of the core idea

Figure 2: Process on Record (POR) process flow

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Figure 3: Novel flow

Potential chemicals for nitride removal include:

• Dilute HF

• HF + HCl mixture

• HFEG

• For milder dHF removal, fast wet etchable hydrogen rich silicon nitride can be used as the hardmask (DHF1A removing > 250A SiN)