Anisotropic etching of polysilicon in a Cl-2/CH3Br/O-2 plasma

The characteristic behaviors of CH3Br are examined first for the dry etchin g of polysilicon in a Cl-2/CH3Br/O-2 plasma. CH3Br is revealed as one of th e excellent additive gases to control anisotropy of the etching profile and to give no undercutting for various types of polysilicons. The fragments f rom CH3Br plasma would act as passivation precursors on the sidewalls in et ch cavity. The decrease of etch selectivity due to the reaction of the C-co ntaining species front CH3Br with the surface O atoms of SiO2 is overcome b y the addition of O-2 into the plasma. (C) 2001 The Electrochemical Society . [DOI: 10.1149/1.1383555] All rights reserved.