In-situ monitoring for CVD processes

• Published in: Thin solid films 2003-10, Vol.442 (1), p.60-65
• Main Authors: Hopfe, V., Sheel, D.W., Spee, C.I.M.A., Tell, R., Martin, P., Beil, A., Pemble, M., Weiss, R., Vogt, U., Graehlert, W.
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Chemical vapour deposition (CVD); Cross-disciplinary physics: materials science; rheology; Diode laser spectroscopy (DLS); Exact sciences and technology; Fourier transform infrared spectroscopy (FTIR); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Tin oxide
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(03)00943-X

Aiming towards process control of industrial high yield/high volume CVD reactors, the potential of optical sensors as a monitoring tool has been explored. The sensors selected are based on both Fourier transform infrared spectroscopy (FTIR) and tunable diode laser spectroscopy (NIR-DLS). The former has the advantage of wide spectral capability, and well established databases. NIR-DLS spectroscopy has potentially high sensitivity, laser spatial resolution, and the benefits of comparatively easier integration capabilities—including optical fibre compatibility. The proposed technical approach for process control is characterised by a ‘chemistry based’ feedback system with in-situ optical data as input information. The selected optical sensors continuously analyze the gas phase near the surface of the growing layer. The spectroscopic data has been correlated with process performance and layer properties which, in turn establish data basis for process control. The new process control approach is currently being verified on different industrialised CVD coaters. One of the selected applications deals with the deposition of SnO 2 layers on glass based on the oxidation of (CH 3) 2SnCl 2, which is used in high volume production for low-E glazing.