| AVS 56th International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuP |
| Session: | Electronic Materials and Processing Poster Session |
| Presenter: | J.L. Shohet, University of Wisconsin-Madison |
| Authors: | J.L. Lauer, University of Wisconsin-Madison S.L. Cheng, Stanford University B.B. Triplett, Stanford University J.L. Shohet, University of Wisconsin-Madison Y. Nishi, Stanford University |
| Correspondent: | Click to Email |
We compare the charging response and defect generation, produced by vacuum ultraviolet (VUV) irradiation, of rapid-thermally annealed (RTA) 4nm thick HfO2 to as-deposited HfO2 on Si substrates. The HfO2 dielectrics were irradiated to 11.6 eV photons. The surface potential of the HfO2 samples was measured before and after VUV irradiation with a Kelvin probe system. The surface potential was determined to be negative before VUV irradiation and positive after irradiation for all samples except the 4nm thick HfO2 layer that was RTAd at 1000C. Paramagnetic defects within the HfO2 samples with and without VUV irradiation were measured with Electron Spin Resonance Spectroscopy (ESR). The VUV-irradiated samples indicate the presences of both E’ and Ex centers. From VUV-spectroscopy, the valence-band structure and location of defects with the band gap of the HfO2 samples were determined and compared to density of states calculations to determine the origin of the electronic states measured. Initial results from VUV-spectroscopy suggest the presence of oxygen-interstitial defects (OID) located within the HfO2 layer and oxygen-deficient Si centers within the SiOx interfacial layer. We show the electronic states of OID in HfO2 line up in energy with oxygen-deficient Si centers within the SiO2 interfacial layer. We believe the oxygen-deficient Si centers are responsible for the accumulation of positive charge in the VUV irradiated HfO2 samples. We conclude that charge exchange between OIDs within HfO2 and the oxygen-deficient Si centers within the SiOx interfacial layer is very important for controlling the radiation-induced trapped charge in HfO2/SiOx/Si dielectric stacks.
Supported by the National Science Foundation under Grant Number DMR-0306582 and the Semiconductor Research Corporation under Contract Number 2008-KJ-1781. The UW Synchrotron Radiation Center is funded by the National Science Foundation under Grant Number DMR-0537588.