AVS 45th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoP

Paper PS-MoP2
Comparison of Feature Profile Evolution for Halogen Plasma Etching of Silicon (100)

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Plasma Science and Technology Poster Session
Presenter: F.P. Klemens, Bell Laboratories, Lucent Technologies
Authors: K.H.A. Bogart, Bell Laboratories, Lucent Technologies
F.P. Klemens, Bell Laboratories, Lucent Technologies
J. Lane, Massachusetts Institute of Technology
M.V. Malyshev, Bell Laboratories, Lucent Technologies and Princeton Univ.
V.M. Donnelly, Bell Laboratories, Lucent Technologies
A. Kornblit, Bell Laboratories, Lucent Technologies
J.T.C. Lee, Bell Laboratories, Lucent Technologies
Correspondent: Click to Email
Feature profile evolution during halogen plasma etching of silicon-based materials is affected by several contributions to the etch mechanism. These aspects, including isotropic chemical etching, broad ion angle distributions, ion scattering within a feature, and redeposition of etching products, can cause deviations from anisotropic etching such as bowed or undercut sidewalls and mictrotrench formation in trench bottoms. Different halogen source gases produce various feature profiles and likely affect changes in the mechanistic components of silicon (Si) etching. Crystalline silicon (100) wafers (p-type, 150 mm) and poly-crystalline silicon (poly-Si) deposited onto silicon dioxide (SiO@sub 2@) were etched in a transformer coupled plasma reactor at two applied rf powers (250, 500 W, bias = 150 W) with Cl@sub 2@, HBr and HCl plasmas. Both Si (100) and poly-Si were patterned with nested and isolated lines and trenches using a SiO@sub 2@ mask. Scanning electron microscopy (SEM) was used to identify feature morphology and make comparisons between different halogen sources. Cross sectional SEM micrographs showed that HBr plasmas produced features with vertical sidewalls and little or no microtrenching. Deviations from anisotropically etched profiles (bowed sidewalls and deep microtrenches) were most severe for wafers etched in Cl@sub 2@ plasmas. Line and trench features for wafers etched in HCl plasmas evolved hybrid profiles; microtrenching and sidewall bowing occurred, but to a lesser degree than for Cl@sub 2@ plasmas. These data indicate that the presence of hydrogen or the type of halogen species in the plasma plays a significant role in feature profile evolution.