AVS 49th International Symposium
    Plasma Science Monday Sessions
       Session PS1-MoA

Paper PS1-MoA5
Electrical Conductivity of Sidewall Deposited Fluorocarbon in SiO@sub 2@ Contact Holes

Monday, November 4, 2002, 3:20 pm, Room C-103

Session: Dielectric Etch I
Presenter: T. Shimmura, Tohoku University, Japan
Authors: T. Shimmura, Tohoku University, Japan
S. Soda, Tohoku University, Japan
S. Samukawa, Tohoku University, Japan
M. Koyanagi, Tohoku University, Japan
K. Hane, Tohoku University, Japan
Correspondent: Click to Email
Predicting the feature profile evolution for high aspect ratio contact hole patterning requires quantitative measurements of the sidewall conductivity in contact holes. This paper reports on On-wafer monitoring of the sidewall current in holes. We were developed the device used for measuring the sidewall conductivity. A SiO@sub 2@ film (500 nm) was deposited between Poly-Si electrodes (300 nm). The holes were fabricated by HF wet etching or conventional ICP etching. The diameter of holes was 0.5 µm, and the numbers of holes were 240000. The sidewall current was measured by supplying the voltage of 20 V between electrodes. When the holes were formed with the wet etching, the sidewall current was 4.5 nA. Conversely, it was 276.8 nA in the case of ICP etching. By removing the deposited polymer, it decreased to 40.9 nA. To clarify the influence of the deposited polymer on conductivity, we also deposited polymer in the fabricated holes using C@sub 4@F@sub 8@ UHF plasma (5mTorr, UHF power: 500W). Then, deposited polymer was exposed Ar plasma (5mTorr, UHF power: 1000W). In XPS studies, the carbon to fluorine ratio of as deposited film was 0.91. After ion irradiation, it changes to 1.86. In FT-IR spectra, characteristic absorption peaks of fluorocarbon films are appearing in 1100 - 1400 cm@super -1@.@footnote 1@ The absorption that appears in neighborhood 1700 cm@super -1@ was increased and shifted to low wave number by ion irradiation. This result shows that ion irradiation causes defluorination and forms unsaturated bond. Additionally, the sidewall current increased to 2181.7 nA from 38.8 nA by ion irradiation. We had found that the high cross-linked and unsaturated fluorocarbon film caused increase in sidewall current. @FootnoteText@ @footnote 1@ N.M.Makie, N.F.Dalleska, D.G.Castner, and E.R.Fischer, Chem. Mater., 9 349 (1997).