IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Plasma Science Wednesday Sessions
       Session PS-WeA

Paper PS-WeA5
High-Density Plasma-Based Etching of Organosilicate Glass (OSG) in C@sub 4@F@sub 8@/Ar and C@sub 4@F@sub 8@/O@sub 2@ Gas Mixtures: Process Results and Diagnostics

Wednesday, October 31, 2001, 3:20 pm, Room 104

Session: Plasma Surface Interactions II
Presenter: M. Fukasawa, University of Maryland, College Park
Authors: M. Fukasawa, University of Maryland, College Park
X. Li, University of Maryland, College Park
X. Wang, University of Maryland, College Park
L. Ling, University of Maryland, College Park
G.S. Oehrlein, University of Maryland, College Park
F.G. Celii, Texas Instruments, Inc.
K.H.R. Kirmse, Texas Instruments, Inc.
Correspondent: Click to Email
We report gas phase and surface studies of high-density plasma etching processes of organosilicate glass (OSG), a low-k oxide, and Si@sub 3@N@sub 4@ and SiC etch stop materials, in C@sub 4@F@sub 8@/Ar and C@sub 4@F@sub 8@/O@sub 2@ gas mixtures. Owing to the presence of methyl groups in the SiO@sub 2@ backbone the etching behavior of OSG differs significantly from that of conventional SiO@sub 2@. The addition of O@sub 2@ can be used to increase the OSG etching rate (e.g. from 900 nm/min for a 1400 W 6 mTorr C@sub 4@F@sub 8@ discharge and a selfbias voltage of -85 V to 1100 nm/min for C@sub 4@F@sub 8@/20% O@sub 2@), but can modify the OSG material by oxidizing methyl groups and reduce the selectivity to the etch stop material. The goal of this work was to establish the key variables that can be used to maximize the etch selectivity of OSG with respect to the etch stop materials while minimizing the OSG modifications. An inductively coupled high-density plasma etching reactor equipped with in situ ellipsometry, optical emission spectroscopy (OES) and mass spectrometry was used. Measurements were made as a function of C@sub 4@F@sub 8@/Ar and C@sub 4@F@sub 8@/O@sub 2@ gas composition for pressures ranging from 6 to 20 mTorr, source power levels up to 1400 W, and as a function of RF bias. Both blanket film etching of OSG, SiO@sub 2@, Si@sub 3@N@sub 4@ and SiC and transfer of hole/trench patterns into OSG were studied as a function of process conditions. We utilized the gas phase characterization results, and X-ray photoelectron spectroscopy (XPS) data of etched films after vacuum transfer, to explain the observed etching behavior, evaluate surface/bulk modifications of the OSG vs. process conditions, and identify the critical factors that enable high quality pattern transfer processes of OSG over Si@sub 3@N@sub 4@ and SiC.