| AVS 60th International Symposium and Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM+PS-TuM |
| Session: | High-k Oxides for MOSFETs and Memory Devices I |
| Presenter: | M. Edmonds, University of California San Diego |
| Authors: | M. Edmonds, University of California San Diego T. Kent, University of California San Diego R. Droopad, Texas State University A.C. Kummel, University of California San Diego |
| Correspondent: | Click to Email |
The dominant crystallographic face of InGaAs(001) based FinFETs is the (110)surface. These sidewall surfaces do not have metallic group III bonds and therefore with proper passivation might provide ideal interfaces to the gate oxide. It has been shown shown that with trimethyl aluminum (TMA) passivation of GaAs(110), monolayer nucleation density with zero lattice disruption can be achieved which is ideal for sub 0.5nm EOT scaling. Furthermore, dual passivation with an oxidant such as H2O(g) has been shown to removes conduction band edge states associated with Al-Ga bonds results fromm TMA bonding. DFT studies confirm that TMA bridge bonds between the Ga and As atoms on the GaAs(110) surface while-OH from H2O(g) dual passivation can readily insert into the Al-Ga bond thereby unpinning the surface. This study focuses on examining and characterizing surface defects and features of cleaved GaAs(110) in comparison with molecular beam epitaxy (MBE) grown InGaA/InP(110) samples via scanning tunneling microscopy/spectrocscopy (STM/STS) studies. Models of the various surface defects are proposed.
The MBE grown InGaAs/InP(110) samples are grown with an As2 cap in order to protect the surface from oxidation. The samples are decapped at 350°C in an ultra-high vacuum chamber system prior to STM imaging. The initial STM image results show the surface contains a much higher step density compared to cleaved GaAs(110). The STM images of MBE grown InGaAs(110) also shows bright site features which have an average height of ~2.5Å and a site width variation from 1.8 nm to 3.6nm. These bright site features are consistent with excess As on the surface from an incomplete decapping procedure, or from surface undercoordinated atoms. A commercially available thermal gas cracker will be used to expose the surface to atomic hydrogen. It is believed this will remove any excess As on the surface and potentially passivating instrisic surface defetcs . The dry in-situ atomic hydrogen cleaning of the MBE InGaAs(110) decapped samples will be compared with the cleaved GaAs(110) samples in aim to remove excess As2 from the surface and make the InGaAs(110) surface comparable in low surface defect sites with cleaved GaAs(110).