In Situ Monitoring of Interfaces and Growth of Amorphous Silicon by Spectroellipsometry

Abstract

ABSTRACTRecent applications of spectroscopie phase modulated ellipsometry, from 0.25 to 11 μm, to study the growth of plasma deposited thin film semiconductors like amorphous (a-Si:H) silicon are reviewed. The high sensitivity of this technique is emphasized. In the infrared (IR), the hydrogen incorporation during a-Si:H growth can be precisely investigated. Photoelectronic quality a-Si:H films grow beneath a hydrogen rich overlayer (a few monolayers thick) containing SiH2. the hydrogen being bonded as SiH in the bulk material. In the ultraviolet (UV) range, the ability of kinetic ellipsometry, with fast time resolution, to study interfaces formation is illustrated. Examples of sharp interfaces are presented. In the case of amorphous silicon-silicon nitride structures, it is shown that an inversion of the deposition sequence of the various layers can lead to a graded transition. A detailed analysis of a growth process involving a chemical reaction with the substrate is illustrated in the case the a-Si:H / Pd interface.