LASER-INDUCED THERMAL-DESORPTION AS AN IN-SITU SURFACE PROBE DURING PLASMA PROCESSING

We report a new technique for detecting adsorbates in real time during plasma processing. During etching of Si(100) in a Cl2 plasma, pulsed XeCl excimer laser irradiation of the surface induces thermal desorption of SiCl(x) (x = 0-4). Desorbing products are detected by either laser-induced fluorescence (for SiCl) excited by the same laser pulse, or by plasma-induced emission (for SiCl and Si) from electron impact excitation. The technique has a time resolution of < 0.1 s and submonolayer sensitivity, and should be applicable to processes at high ambient pressure.