AVS 50th International Symposium
    Applied Surface Science Wednesday Sessions
       Session AS-WeM

Invited Paper AS-WeM1
Spectroscopic Characterization of High-k Dielectrics: Applications to Interface Electronic Structure and Stability Against Chemical Phase Separation

Wednesday, November 5, 2003, 8:20 am, Room 324/325

Session: High-K Materials Interface Analysis
Presenter: Cristiano Krug, North Carolina State University
Authors: G. Lucovsky, North Carolina State University
Cristiano Krug, North Carolina State University
Correspondent: Click to Email
The lowest conduction band states of high-k transition metal and rare earth dielectrics are associated with localized anti-bonding d*-states. Combining X-ray absorption spectroscopy, XAS, with vacuum ultra-violet spectroscopic ellipsometry, VUV SE, photoconductivity, PC, and internal photoemission, IPE, provides a way to study final state effects, in particular different d*-states, and d*-s*-state splittings which can then be compared with ab initio calculations on small clusters. These studies prove important insights into empirical correlations between i) band gaps, and ii) conduction band offset energies with respect to crystalline silicon and atomic d-state energies which apply to both transition metal and rare earth dielectrics, including binary oxides, and silicate and aluminate alloys. These results provide important insights into optimization of silicate and aluminate alloys for minimum direct tunneling at a given equivalent oxide capacitance. Combining Fourier transform infra red spectroscopy, FTIR, and derivative X-ray photoelectron spectroscopy, XPS, with extended X-ray absoroption fine structure spectroscopy, EXAFS, provides an unambiguous way to differentiate between chemical phase separation with different degrees of crystallization in Zr and Hf silicate gate dielectrics, and at their interfaces with Si. This is of importance for semiconductor device processing since chemical phase separation at 900C (1000C) in silicon dioxide-rich Zr (Hf) silicates not detectable by X-ray diffraction, XRD, reduces gate dielectric capacitance, and therefore can reduce current drive in field effect transistors, FETs.