| 摘要 |
<p>Formation of a layer on a substrate (16) is monitored by impinging P-polarized light on the layer during layer formation at approximately the Brewster's angle for the substrate, and detecting radiation (46) which is reflected from the structure. In heterostructure formation, an interference signal having a predetermined periodicity is monitored. Maxima and/or minima in the interference signal are monitored and an amplitude modulated fine signal which is superimposed on the interference signal is also monitored. The layer formation process is controlled based on the monitored interference signal, ratio of the maxima and/or minima, fine signal, fine signal amplitude modulation and/or combinations thereof by comparing the signals to a mathematical model or empirical data reference (84). A heterostructure formation or etching can also be used to calibrate a homostructure formation. Scattered light (48) may also be correlated to the reflected light to reduce the scattering component of the reflected light.</p> |
