AVS 53rd International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThA

Paper AS-ThA8
Characterization and Metrology Challenges in SiON Gate Thin Films for ULSI Technology

Thursday, November 16, 2006, 4:20 pm, Room 2005

Session: Combined Methods or Multiple Methods
Presenter: G. Conti, Applied Materials
Authors: G. Conti, Applied Materials
C. Lazik, Applied Materials
Y. Uritsky, Applied Materials
T.C. Chua, Applied Materials
C. Czarnik, Applied Materials
S.R. Bryan, Physical Electronics
T. Gustafsson, Rutgers University
E. Garfunkel, Rutgers University
Correspondent: Click to Email
Silicon oxynitrides (SiON) films are presently used as a replacement of SiO2 gate dielectric film in oxide semiconductor field effect transistor MOSFET. SiON films can be grown by a variety of processes such as: thermal oxy-nitridation, low energy ion implantation, chemical vapor deposition, and atomic layer deposition. Depending on the growth process and the process parameters, nitrogen can pile up at or near the Si/SiO2 interface, be uniformly distributed throughout the film, or be enriched at the interface of the poly-Si gate electrode. The N distribution significantly affects the electrical properties of the gate dielectric layer; therefore, during process development the physical properties of the SiON film (thickness, composition, and atomic depth distributions) must be determined. Whereas most of the analytical techniques become less effective as film thickness drops towards the 10A range, angle resolved x-ray photoelectron spectroscopy (AR-XPS) becomes a very effective technique in this range. AR-XPS is capable of providing precise thickness and detailed information on elemental and chemical composition. However, extracting a depth distribution from the data requires calculating the angular response for trial models and comparing to the data. Since a fit is not a guarantee of trustworthy, AR-XPS depth profiles results were compared to other surface techniques. We characterized "golden standard" samples for N dose and N profile by TOF-SIMS, and by MEIS, and compared the results to AR-XPS. TOF-SIMS instead predicted a broad and flat profile even for box-like profiles created by CVD and it does not capture any distinct SiO2 layer beneath the SiN layer. MEIS agrees with AR-XPS fit confirming our ability to measure depth-profile non destructively. In addition, preliminary results from TEM/EELS analysis agree with AR-XPS and MEIS results.