Abstract

Future technology for ultra large scale integrated semiconductor circuits will need low temperature processes for growing and etching thin films. An important thin film is that of SiO₂ on top of Si. The composition and structure of this film and its interface with Si partly determines the electrical properties of the resulting devices. Detailed information about composition and structure of thin films can be obtained with the use of vibrational spectroscopy, e.g. electron energy loss- (EELS), Raman- or infrared absorption spectroscopy (IRAS). EELS features high sensitivity and a large spectral range but its disadvantages are low resolution (> 40 cm^-1) the risk of electron beam induced reactions and its limitation to pressures below 10^-4 Pa. (ref. l). With Raman spectroscopy enough sensitivity is obtained only when using special modified metal surfaces (SERS). Since infrared spectroscopy combines high resolution with adequate sensitivity and furthermore is not limited to low pressure environments, it is an obvious choice for the study of interaction of plasmas with thin films and interfaces. Its sensitivity however poses problems for frequencies below 800 cm^-1.

© 1987 Optical Society of America