AVS 52nd International Symposium
    Electronic Materials and Processing Monday Sessions
       Session EM-MoM

Paper EM-MoM8
Spectroscopic Studies of Band Alignment in Metal/High-k Dielectric/Si Gate Stacks

Monday, October 31, 2005, 10:40 am, Room 309

Session: Electronic Properties of High-k Dielectrics and their Interfaces
Presenter: E. Bersch, Rutgers University
Authors: E. Bersch, Rutgers University
S. Rangan, Rutgers University
O. Celik, Rutgers University
W. Jiang, Rutgers University
C.L. Hsueh, Rutgers University
E. Garfunkel, Rutgers University
R.A. Bartynski, Rutgers University
Correspondent: Click to Email
The continued scaling of CMOS devices requires the replacement of SiO2 with a higher dielectric constant oxide, and of the doped poly-silicon gates with metal electrodes. The band alignment at these interfaces is critical in that there must be sufficient valence and conduction band offsets (> 1.0eV) to limit the leakage current across the dielectric to a tolerable level. We have measured the conduction and valence band offsets of metal/high-k/Si gate stacks with inverse photoemission and photoemission, respectively, for various combinations of candidate gate metals and alternate dielectrics, in situ. Using inverse photoemission, the conduction band minimum (ECBM) is found to be 2.2 eV above the Fermi level ALD grown HfO2/Si films. This value is reduced by ~ 0.3 eV on films annealed to 700oC. The energy of the CBM of hafnium silicate films grown on Si that were subjected to a 1000oC anneal is found to be independent of silicate concentration, while similarly processed nitrided hafnium silicate films annealed exhibit in increase in the CBM energy with increasing silicate concentration. Upon metallization with Ru, ECBM of each of these systems decreases by ~ 0.3eV. We have also measured these offsets on the same samples with x-ray absorption spectroscopy and internal photoemission. The results of all of these methods will be compared to each other, and the merits of each method will be discussed.