Jpn. J. Appl. Phys. 22 (1983) pp. 712-718  |Next Article|  |Table of Contents|
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Undercut in a CF₄-Based High-Pressure Poly-Si Plasma Etch

A. F. Borghesani and F. Mori

(Received May 28, 1982; revised manuscript revised October 6, 1982; accepted for publication December 18, 1982)

The behaviour of the plasma etching of polycrystalline Si (P-doped and undoped) in a CF₄-based high-pressure glow discharge is studied as a function of the power density, of the exposed poly-Si surface area (the so called loading effect), of the flow rate of CF₃Cl and of the flow rate of N₂O and O₂ as additive gases.
Partially in contrast with the current results reported in the literature, the experimental data here presented show that P-doped poly-Si is etched slower than undoped poly-Si in the mixture CF₄+CF₃Cl+N₂O as well as in the mixture CF₄+CF₃Cl+O₂, probably as a result of the different interaction mechanisms between substrate and gaseous reactants, which could be established at such high pressure and flowrate as in our experiment.
Furthermore, our data reveal that the lateral etch rate (or undercut) is critically determined by the effective concentration of atomic F.
Finally, we observed that CF₃Cl has a clear anisotropic mechanism of etch.

URL: http://jjap.jsap.jp/link?JJAP/22/712/
DOI: 10.1143/JJAP.22.712

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