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METHOD AND SYSTEM FOR CRYSTALLOGRAPHIC ETCHING FOR PATTERNING UNIFORM AND SMOOTH FINS

IP.com Disclosure Number: IPCOM000238471D
Publication Date: 2014-Aug-27
Document File: 1 page(s) / 23K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system is disclosed for patterning fins used in non-planar device structures such as FinFETs or Tri-Gates. A process known as crystallographic etching is used for cleaning any kind of roughness from the fins. This results in developing straight fins having smooth surfaces.

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METHOD AND SYSTEM FOR CRYSTALLOGRAPHIC ETCHING FOR PATTERNING UNIFORM AND SMOOTH FINS

New non-planar device structures called FinFETs or Tri-Gates are used in state-of-the-art CMOS (Complementary metal-oxide-semiconductor) logic. The fins which form active channel region and often part of source and drain can be challenging to pattern cleanly, due to their small size, pitch, and high aspect ratio.

The system and method disclosed herein performs crystallographic etching after initial fin definition to form straight fins having smooth surfaces.

Crystallographic etching helps in cleaning any kind of roughness existing from the patterning and fin definition, and results in forming triangular fins having two top surfaces.

Moreover, in accordance with the method disclosed herein, the aspect ratio also gets fixed for the fins, since sidewall angle is completely determined by a crystal lattice during crystallographic etching.

In accordance with an exemplary implementation of the method, the fins are defined roughly with using conventional fin definition. Thereafter, crystallographic etching is performed to create triangular fins having two top surfaces. In case, the triangular fins are too small, they can be transformed into Si nanowires. In an embodiment, thermal processing or other etching may be performed for further shape alteration. Further, undercut etch may optionally be performed in the gate region to separate fin or nanowire from underlying material. Subsequent...