Contactless electromodulation for in situ characterization of semiconductor processing

Abstract

We present results of a new contactless electroreflectance (CER) mode which has considerable potential for in situ monitoring. This method utilizes a condenser-like system, one electrode consisting of a transparent conductive coating on a transparent substrate which is separated from the sample surface by a thin layer of air (or other ambient). In order to demonstrate the utility of this approach we have measured the CER spectra from (a) bulk Hg0.8Cd0.2Te (80 and 300 K) sputtered with Xe ions as well as (b) (001) n- and p-type GaAs structures with large, uniform electric fields. The latter configurations can be used to investigate Fermi level pinning effects and metallization. Studies were carried out as a function of temperature (10 < T < 600 K) yielding a temperature dependence of surface barrier height. The relative merits of CER and photoreflectance will be discussed. © 1993.