TY - JOUR
T1 - Combined wavelength and frequency modulation spectroscopy
T2 - A novel diagnostic tool for materials processing
AU - Sun, H. C.
AU - Whittaker, E. A.
AU - Bae, Y. W.
AU - Ng, C. K.
AU - Patel, V.
AU - Tam, W. H.
AU - McGuire, S.
AU - Singh, B.
AU - Gallois, B.
PY - 1993/2/20
Y1 - 1993/2/20
N2 - By applying both low-frequency wavelength modulation and high-frequency phase modulation to a laser diode, we develop a sensitive, high-bandwidth chemical diagnostic tool that is applicable to a variety of gas-phase processing environments. Specific chemical species are identified and monitored through their infrared absorption spectra, and the modulation methods allow for sensitive detection that is free of window and other reflection-driven interference fringes. Absorbance limits of 5.3 × 10−8 and 1.9 × 10−7 are obtained for an AlGaAs diode laser and a lead-salt diode laser, respectively. We discuss applications to plasma etching and chemical vapor deposition.
AB - By applying both low-frequency wavelength modulation and high-frequency phase modulation to a laser diode, we develop a sensitive, high-bandwidth chemical diagnostic tool that is applicable to a variety of gas-phase processing environments. Specific chemical species are identified and monitored through their infrared absorption spectra, and the modulation methods allow for sensitive detection that is free of window and other reflection-driven interference fringes. Absorbance limits of 5.3 × 10−8 and 1.9 × 10−7 are obtained for an AlGaAs diode laser and a lead-salt diode laser, respectively. We discuss applications to plasma etching and chemical vapor deposition.
KW - Laser absorption spectroscopy
KW - Metal-organic chemical vapor deposition
KW - Plasma etching
KW - Tunable diode laser
UR - http://www.scopus.com/inward/record.url?scp=0000215347&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0000215347&partnerID=8YFLogxK
U2 - 10.1364/AO.32.000885
DO - 10.1364/AO.32.000885
M3 - Article
AN - SCOPUS:0000215347
SN - 1559-128X
VL - 32
SP - 885
EP - 893
JO - Applied Optics
JF - Applied Optics
IS - 6
ER -