AVS 53rd International Symposium
    Nanometer-scale Science and Technology Thursday Sessions
       Session NS-ThP

Paper NS-ThP27
Etching of Ion-implanted Silicon Nitride and Oxide in a Weakly Anisotropic Dry Etch Process

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Nanoscale Science and Technology Poster Session
Presenter: P.K. Subramanian, AMD Inc.
Authors: P.K. Subramanian, AMD Inc.
S. Panda, IBM Microelectronics
M.P. Belyansky, IBM Microelectronics
Correspondent: Click to Email
Etching silicon nitride films deposited over other (e.g., silicon oxide) films is frequently used in different process schemes in the semiconductor industry. Thus, etch selectivity and throughput of the etch process are important factors. Two commonly available unit processes, ion implantation and rapid thermal anneal can be used to tailor the etch rate of various nitride films. In this study, we report nitride film etch rates after anneal-only, implantation-only and implantation combined with anneal. We use different types of nitride films - deposited by LPCVD, RTCVD and PECVD techniques. It is shown that along with composition and structure, the intrinsic stress of these films affects the etch rates. Correlations of the etch rates with these basic film properties is discussed. Ion implanted silicon nitride (LPCVD, RTCVD and PECVD) films exhibit higher etch rates in weakly anisotropic dry etch compared to as-deposited films. Similar effect has been observed during wet etch of implanted nitride in some earlier studies. The observed increase in etch rate depends on both the concentration and the composition of implanted species. The implanted and unimplanted films were annealed at 950C and the etch rates determined and correlated with the stress in the films. The behavior of implanted SACVD LTO (low temperature oxide) and high temperature oxide (HTO) under the same implant and etch conditions are also studied. The etch rate dependence of LTO on implant conditions is not significant under the process conditions explored. The etch rate of implanted films after anneal is equivalent to that of as deposited films. Thus, the etch selectivity between nitride and oxide films can be tailored to meet process design requirements.