AVS 46th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS2+EM-TuA

Paper SS2+EM-TuA9
Resonance-Enhanced Multiphoton Ionization Studies of the Etching of Silicon by Molecular Chlorine

Tuesday, October 26, 1999, 4:40 pm, Room 6C

Session: Semiconductor Surface Chemistry
Presenter: T.A. Barckholtz, University of Colorado, Boulder
Authors: T.A. Barckholtz, University of Colorado, Boulder
L. McDonough, University of Colorado, Boulder
S.R. Leone, University of Colorado, Boulder
Correspondent: Click to Email
Laser ionization time-of-flight mass spectrometry is a powerful technique for characterizing the neutral products of the etching of semiconductor materials. We previously showed that single photon ionization (SPI), which uses the 9th harmonic of a Nd:YAG laser, provides excellent characterization of the neutral products of the etching of silicon by molecular chlorine, both thermally@footnote 1@ and during ion-enhanced etching.@footnote 2@ Two drawbacks of using the SPI technique are the low laser power available (ca. 10 µJ/pulse) and the lack of resolution of the state distributions (electronic, vibrational, rotational) of the products. To address these deficiencies, we recently implemented a Nd:YAG-pumped dye laser on an etching apparatus that enables resonant electronic multiphoton ionization (REMPI) schemes for the detection of the neutral species. Because of the greater laser power available (several mJ/pulse), the detection sensitivity has been dramatically increased. For example, the REMPI signal intensity of neutral atomic Si during thermal etching is approximately 200 times greater than the SPI intensity. Furthermore, complete state resolution of the Si spin-orbit (@super 3@P@sub 2@, @super 3@P@sub 1@, and @super 3@P@sub 0@) and metastable (@super 1@D@sub 2@) states is obtained. For SiCl, due to its broad rotational and vibrational distributions, the detection sensitivity is increased by a smaller factor, and only partially resolved state distributions are possible. We plan to use the enhanced sensitivity and partial state resolution to investigate the mechanism for the ion-enhanced etching of silicon by chlorine in greater detail than was possible with the SPI technique. The results of these studies will be compared with the predictions of published molecular dynamics simulations. @FootnoteText@ @footnote 1@Materer, N.; Goodman, R. S.; Leone, S. R. JVST A 1997, 15, 2134-2142. @footnote 2@Goodman, R. S.; Materer, N.; Leone, S. R. JVST A, submitted for publication.