Time-Resolved Quantum Cascade Laser Absorption Spectroscopy of Pulsed Plasma Assisted Chemical Vapor Deposition Processes Containing BCl 3

• Published in: Japanese Journal of Applied Physics Vol. 50; no. 8S1; p. 8
• Main Authors: Lang, Norbert, Hempel, Frank, Strämke, Siegfried, Röpcke, Jürgen
• Format: Journal Article
• Language: English
• Published: 01.08.2011
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.50.08JB04

In situ measurements are reported giving insight into the plasma chemical conversion of the precursor BCl 3 in industrial applications of boriding plasmas. For the online monitoring of its ground state concentration, quantum cascade laser absorption spectroscopy (QCLAS) in the mid-infrared spectral range was applied in a plasma assisted chemical vapor deposition (PACVD) reactor. A compact quantum cascade laser measurement and control system (Q-MACS) was developed to allow a flexible and completely dust-sealed optical coupling to the reactor chamber of an industrial plasma surface modification system. The process under the study was a pulsed DC plasma with periodically injected BCl 3 at 200 Pa. A synchronization of the Q-MACS with the process control unit enabled an insight into individual process cycles with a sensitivity of 10 -6 cm -1 ·Hz -1/2 . Different fragmentation rates of the precursor were found during an individual process cycle. The detected BCl 3 concentrations were in the order of 10 14 molecules·cm -3 . The reported results of in situ monitoring with QCLAS demonstrate the potential for effective optimization procedures in industrial PACVD processes.