讲座信息

Recent progress on semiconductor/high-k interface preparation for   post-Si CMOS gate stacks

 

L. Yu1, H.D. Lee1, T Feng1, D.D.T Mastrogiovanni2, A. Wan2, T. Gustafsson1 and E. Garfunkel1,2

 

1Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019, USA

 

2Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Rd., Piscataway, NJ, 08854, USA

 

Email: leiyu@physics.rutgers.edu

 

The ideas of using high-k dielectrics as gate oxide and high mobility semiconductor as channel material are promising means of prolonging the scaling of CMOS technology to post Silicon era. However, it has been extremely challenging to produce a high quality oxide/channel interface that yields sufficient device performance for future CMOS. The unwanted chemical species such as residue native oxide, surface carbon, and hydro-carbon can result in defect states at the interface or inside dielectrics.  These states can enhance carrier scattering and degrade device threshold voltage.  We will first report on wet-chemical cleaning of Ge(100) substrates and subsequent surface passivation using aqueous ammonia sulfide (NH4)2S. Our experiments suggest the combined treatment of H2SO4/H2O2 and sulfur passivation greatly improves the HfO2/high-k/Ge interface quality, and interface state densities of Dit<1011 eV-1cm-2 near the mid-gap can be obtained.  We have also studied the effect of the trimethylaluminum (TMA) precursor on the reduction of surface “native” oxides from GaAs substrates using medium energy ion scattering spectroscopy (MEIS), x-ray photoelectron spectroscopy (XPS) and electrical measurements. Our data show that after one single TMA pulse most of the native oxide is reduced and an oxygen-rich aluminum oxide layer is formed. Al2O3 films grown with the normal ALD cycles of TMA and water show that the growth rate of the Al oxide during this initial reduction of the native oxides is faster than the rate once this reduction is completed. Furthermore, the results of C-V measurements of Al2O3/GaAs grown under the same conditions along with post deposition annealing indicate a good quality interface. Similar native oxide reduction effect are observed on Ge surface, even though the mechanism for oxide reduction maybe very different from GaAs case.

 

时间:2009年12月22日下午3:30
地点:微电子楼B213室
演讲人:Dr. Lei Yu

 

 

Copyright© 2003-2018 复旦大学微电子学院
联系我们