Analysis of Surface Roughness of Silicon Surfaces by Reflection Electron Energy Loss Spectroscopy

Abstract

The quantification of semiconductor surface roughness in the 0.5 - 10 nm range is a problem of current scientific and technological interest. Surface roughness measurements are also of great technological interest, particularly for silicon, since the starting surface roughness affects the roughness and ultimate quality of transistor gate dielectrics and other reacted or deposited layers. While atomic force microscopy and other scanning probe methods are now in widespread use for ex situ surface roughness evaluation, this is considerable interest in developing in situ methods for surface roughness measurement during growth or etching. Candidate in situ roughness analysis methods currently include reflection high energy electron diffraction (RHEED) and RHEED oscillations, widely used for monolayer roughness measurements, ellipsometry, and X-ray reflectivity. In this summary, we describe another method: the use of low-loss inelastic electron scattering measurements using reflection electron energy loss spectroscopy (REELS) to investigate silicon surface roughness.