AVS 53rd International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS1-MoM

Paper PS1-MoM8
New Challenges in Etching Ultra Low-k Dielectrics for 45nm and Beyond

Monday, November 13, 2006, 10:20 am, Room 2009

Session: Etch for Advanced Interconnect I
Presenter: A. Li, Applied Materials, Inc.
Authors: A. Li, Applied Materials, Inc.
K. Zhou, Applied Materials, Inc.
Y. Zhou, Applied Materials, Inc.
R. Cheung, Applied Materials, Inc.
S. Parikh, Applied Materials, Inc.
M. Armacost, Applied Materials, Inc.
Correspondent: Click to Email
Abstract Ultra low-k (ULK) dielectrics with k-values below 2.5 have been extensively evaluated for 45 nm node and beyond. Most ULK dielectrics have highly connected pore structure and therefore, exert new challenges during plasma processing. Conventional O2-based plasma resist stripping processes can cause significant loss of -CH3 groups, surface densification and pore collapse in ULK, and therefore, lead to film shrinking, profile distortion and an increase of its k value. The pore structures can also induce surface roughness and micro trenching. In this paper, physical findings on ULK damage and rough etch front/micro trenching and electrical validations in a high frequency capacitive coupled plasma etch chamber have been reported. Both O- and N- based chemistry have been investigated for in-situ resist stripping and the dependences of damage and etch front on gas flow rates, pressure, rf power and power ratio have been studied. Auger Electron Spectroscopy (AES) and Electron Energy Loss Spectroscopy (EELS) have been employed to probe the degree and depth of chemical composition changes in the modified ULK layer. The results suggest that in-situ stripping plays an important role in controlling ULK damage and final ULK etch front. The ULK damage and rough front/micro trenching formation mechanisms have also been discussed.