AVS 46th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoP

Paper PS-MoP3
Studies on SiF@sub x@ Radicals in Fluorosilane Plasmas Used for Silicon Etching and Deposition

Monday, October 25, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: K.L. Williams, Colorado State University
Authors: K.L. Williams, Colorado State University
C.I. Butoi, Colorado State University
E.R. Fisher, Colorado State University
Correspondent: Click to Email
Fluorosilane plasmas are used in the microelectronics industry for etching of Si/SiO@sub 2@ and for deposition of fluorinated silicon-based materials (a-Si:H,F). Currently, fluorinated a-Si films are used in the fabrication of solar cells, photoreceptors, and thin film transistors. In spite of such high quality film production, there is still controversy over the mechanistic aspects of etching and deposition processes. Moreover, fundamental chemical information on plasma species such as SiF@sub x@ radicals is not available. Here, the surface reactivity of SiF@sub 2@ radicals during plasma processing of a silicon substrate using the imaging of radicals interacting with surfaces (IRIS) technique is reported. The molecular beam sources are 100% SiF4, 90/10 SiF4/H2, and 50/50 SiF4/H2 plasmas. Preliminary results show scatter ratios of 2.36 ± 0.08, 2.78 ± 0.08, 2.79 ± 0.13, and 3.08 ± 3.08 ± 0.11 for 30 sccm, 80 W and 170 W, and 15 sccm, 80 W and 170 W, SiF@sub 4@ plasmas, respectively. Scatter ratios >1 indicate SiF@sub 2@ is generated at the surface. Significant decreases in SiF@sub 2@ scatter are observed for SiF@sub 2@/H@sub 2@ plasmas. With these plasmas, SiF@sub 2@ scatter ratios are 1.31 ± 0.08 (10% H@sub 2@, 80 W), 1.48 ± 0.10 (10% H@sub 2@, 170 W), and 2.44 ± 0.13 (50% H@sub 2@, 170 W). These results are correlated with data from surface characterization by Fourier transform infrared spectroscopy (FTIR) and profilometry of films deposited under various plasma parameters (applied rf power, pressure, and % H@sub 2@ addition), as well as optical emission spectra for the fluorosilane plasmas studied.