In situ investigation of the amorphous silicon/silicon nitride interfaces by spectroellipsometry

Abstract
We present an in situ study, by spectroellipsometry, of interfaces between amorphous silicon (a‐Si:H) and silicon nitride (a‐SiNx). The nature of the interface between amorphous silicon and silicon nitride depends on the order of deposition. A behavior compatible with an atomically abrupt interface is observed when a‐SiNx is deposited on top of a‐Si:H. On the contrary, a graded transition with a width estimated at ≊15 Å is observed when a‐SiNx is deposited first. An NH3 plasma treatment has little influence on the interface properties. These different behaviors are attributed to the plasma process.