AVS 49th International Symposium
    Plasma Science Thursday Sessions
       Session PS-ThA

Paper PS-ThA4
The Effect of Aspect Ratio on the Etching Properties of Porous Low-k Material in Fluorocarbon Plasma

Thursday, November 7, 2002, 3:00 pm, Room C-103

Session: Dielectric Etch II
Presenter: S.-W. Hwang, Seoul National University, Korea
Authors: S.H. Moon, Seoul National University, Korea
S.-W. Hwang, Seoul National University, Korea
G.-R. Lee, Seoul National University, Korea
J.-H. Min, Seoul National University, Korea
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As the critical dimension of integrated circuit devices rapidly shrinks to sub 0.1µm range, micro-structures such as trench, contact and via holes have high aspect ratios and consequently the issue of the aspect-ratio-dependent-etching (ARDE) becomes important. In ARDE study, information about the surface properties of the sidewall and the bottom inside the features is important, but there are few studies about this, especially in low-k interlayer dielectric etching, because the direct analysis of the surface in real features is difficult. In this study, we used a Faraday cage, which allowed us to control the ion incident angle on the substrate, and investigated in macroscopic scale the change in the roughness and chemical composition of porous low-k silsesquioxane with the aspect ratio of trench-shaped structure after etching in CF@sub 4@ and CHF@sub 3@ plasmas. For the etching experiments, we placed trench structures made of porous silsesquioxane inside the Faraday cage, and the samples were processed at 4mTorr, 600W source power, and -100V bias voltage in TCP etcher. The sidewall height of the samples was fixed at 1cm and the bottom width was varied between 1mm and 1cm such that the aspect ratio of the trench structure was varied between 10 and 1. Etch rates of the bottom and the sidewall of the samples for different aspect ratios were correlated with their surface properties observed by AFM, AES, and FT-IR.