Berlin 2001 – scientific programme

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P: Plasmaphysik

P 2: Plasma Technology, Diagnostics I

P 2.2: Talk

Monday, April 2, 2001, 16:45–17:00, 2032

Investigation of Sputtered Silicon by Cavity Ringdown Spectroscopy — •Stefan Geisler, Albrecht Brockhaus, Axel Schwabedissen, and Jürgen Engemann — Forschungszentrum für Mikrostrukturtechnik - fmt, Bergische Universität-GH Wuppertal, Obere Lichtenplatzer Straße 336, D - 42287 Wuppertal

In many plasma sources the plasma is contaminated by silicon generated by eroding quartz (SiO₂) often used as wall or window material. To investigate the properties of the gas phase silicon we analyze the sputtering of silicon and quartz. This is done by using a setup for absolute density measurements of spatially resolved silicon. Therefore a high sensitive absorption spectroscopy technique - the cavity ringdown spectroscopy (CRDS) - is applied in the UV light range. This method is well suited for the investigation of sputtered gas phase silicon. In our setup a monocrystalline silicon wafer or a quartz target is sputtered by an argon or oxygen ion beam with different energies. The silicon ground state density is obtained from the absorption profiles of the Si I 3s²3p²−3s²3p4s multiplett at 252 nm. The particle energy can be calculated by the Doppler broadening of the signal. The sensivity of the CRDS enables the detection of Si densities down to 2×10⁶ cm⁻³. Typical density values are 10⁸ − 10¹⁰ cm⁻³. With the results one can calculate the sputter yield of the process as a function of the ion energy and the angle of incidence. This is compared to the results of TRIM simulations and the mathematical model of Sigmund.