A differential Hall effect measurement method with sub-nanometre resolution for active dopant concentration profiling in ultrathin doped Si1-x Ge x and Si layers.

Richard Daubriac,Sébastien Kerdilès,Rémi Beneyton,Pablo Acosta Alba,Hiba Rizk,Richard Monflier,Emmanuel Scheid,Filadelfo Cristiano,Sylvain Joblot

doi:10.3762/bjnano.9.184

Abstract

In this paper, we present an enhanced differential Hall effect measurement method (DHE) for ultrathin Si and SiGe layers for the investigation of dopant activation in the surface region with sub-nanometre resolution. In the case of SiGe, which constitutes the most challenging process, we show the reliability of the SC1 chemical solution (NH4OH/H2O2/H2O) with its slow etch rate, stoichiometry conservation and low roughness generation. The reliability of a complete DHE procedure, with an etching step as small as 0.5 nm, is demonstrated on a dedicated 20 nm thick SiGe test structure fabricated by CVD and uniformly doped in situ during growth. The developed method is finally applied to the investigation of dopant activation achieved by advanced annealing methods (including millisecond and nanosecond laser annealing) in two material systems: 6 nm thick SiGeOI and 11 nm thick SOI. In both cases, DHE is shown to be a uniquely sensitive characterisation technique for a detailed investigation of dopant activation in ultrashallow layers, providing sub-nanometre resolution for both dopant concentration and carrier mobility depth profiles.

Highlights

The research efforts made throughout the last decades have made it possible to keep the momentum for a continuous miniaturization of electronics devices
Within the recent development of the 3D-sequential integration technology at CEA-LETI, laser annealing is being investigated as a low thermal budget solution for achieving dopant activation in the top transistor level without degrading the performance of the transistors located at the bottom [39]
In the case of SiGe, which constitutes the most challenging process, we showed the reliability of the SC1 chemical solution thanks to its slow etch rate, stoichiometry conservation and low roughness generation

Summary

Introduction

The research efforts made throughout the last decades have made it possible to keep the momentum for a continuous miniaturization of electronics devices. Thanks to Van der Pauw test structure, probe penetration has been circumvented, while conventional and differential Hall effect measurements described in the previous sections have been used to investigate dopant activation in laser-annealed ultrathin SiGeOI layers.

Results

Conclusion