AVS 52nd International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS1-MoA

Paper PS1-MoA8
Analysis and Impact of F Penetration into low-k Dielectrics during Plasma Etch

Monday, October 31, 2005, 4:20 pm, Room 302

Session: Dielectric Etch I
Presenter: C. Labelle, Advanced Micro Devices Inc.
Authors: R. Augur, Advanced Micro Devices Inc.
C. Labelle, Advanced Micro Devices Inc.
C. Parks, IBM Corporation
S. Mehta, IBM Corporation
N.C.M. Fuller, IBM Corporation
Correspondent: Click to Email
The semiconductor industry's move towards incorporating porous low-k dielectrics in future technology generations raises many questions about the thermal, mechanical, and chemical interactions between porous dielectrics and the different environments they will encounter during integration. This paper reports detailed analysis of F penetration into porous and dense SiCOH-based low-k dielectrics, introduced during plasma etch. SIMS depth profiling was used to compare the concentration of F in etched and non-etched regions. For porous materials, the F concentration was found to be approximately 5 times higher in via-etched regions, and lateral penetration occurred throughout the thickness of 300nm films. Profiles were similar for spin-on (SOD) and chemical vapor deposited (CVD) films, even though the pore-size distribution and average pore size were different. Furthermore, profiles from dense CVD low-k films were also similar to those from porous films, even though the etch conditions were very different for the two cases. These results suggest porosity does not play a major role in F diffusion into SiCOH-based low-k materials. Profiles from the bottom of wide trenches were also similar to via-etched cases: high F concentration compared to non-etched regions, and penetration to 100nm below the trench bottom. The results of this study show F can be incorporated in low-k dielectric films during etch, and not completely removed during the subsequent resist strip. The F can interact with the strip chemistry to significantly etch the ultra-low-k material, and may cause reliability problems later.