AVS 51st International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session DI+PS-TuM

Paper DI+PS-TuM11
Annealing of Hafnium Oxide Grown on Silicon by Atomic Layer Deposition: Changes in Interfacial Structure

Tuesday, November 16, 2004, 11:40 am, Room 304C

Session: High-k Dielectrics: Growth and Processing
Presenter: G. Jursich, American Air Liquide
Authors: A. Deshpande, University of Illinois at Chicago
R. Inman, American Air Liquide
G. Jursich, American Air Liquide
C. Takoudis, University of Illinois at Chicago
Correspondent: Click to Email
Thin films of hafnium oxide are deposited on Si(100) substrates by means of atomic layer deposition (ALD) using tetrakis(diethylamino)hafnium as the hafnium precursor and subsequently annealed at various temperatures (600-1000 C) under Ar atmosphere. The resulting composition and purity of the films are determined at different substrate temperatures using x-ray photoelectron and Fourier transform infrared (FTIR) spectroscopies. The chemical and physical structure of the film/interfacial regions are analyzed using a combination of Z-contrast imaging and electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope. Depth profiling of film/interfacial regions were obtained using high-resolution angle resolved x-ray photoelectron spectroscopy (XPS). The pre-annealed films showed presence of a very thin silicon oxide at the film/substrate interface that originated from the residual surface oxide resulting from the wet chemical surface cleaning procedure used. Thus, no growth of interfacial region is observed from deposition alone. However, the post annealed films show increase in interfacial silicon oxide thickness coupled with formation of silicate-like structure as the annealing temperature is increased. This is evident from independent sets of data of FTIR spectroscopy and XPS. At the highest annealing temperature used (i.e., 1000 ºC), formation of silicide is observed at the interface. From these measurements detail information on the interfacial changes incurring from thermal annealing are obtained when there is a very thin layer of silicon oxide present on the silicon substrate. These results will be discussed in view of the intermediate SiO2 in terms of HfO2:SiO2 inter-diffusion and the formation of silicate-like structure.