AVS 50th International Symposium
    Thin Films Monday Sessions
       Session TF-MoM

Paper TF-MoM9
Demonstration of AlN ALD Using Hydrazine as the Nitrogen Precursor

Monday, November 3, 2003, 11:00 am, Room 329

Session: Atomic Layer Deposition
Presenter: F.H. Fabreguette, University of Colorado
Authors: F.H. Fabreguette, University of Colorado
T.E. Seidel, Genus, Inc.
S.M. George, University of Colorado
Correspondent: Click to Email
Aluminum nitride (AlN) has attracted widespread attention due to its remarkable thermal, electronic and mechanical properties leading to numerous applications. AlN growth by chemical vapor deposition (CVD) is accomplished using trimethylaluminum (TMA) and ammonia (NH@sub 3@) precursors. AlN atomic layer deposition (ALD) has also been attempted using TMA and NH@sub 3@. Unfortunately, high ALD temperatures are required where TMA pyrolysis is a problem. Lower ALD reaction temperatures where TMA will not decompose can be obtained using hydrazine, N@sub 2@H@sub 4@ , as the nitrogen precursor. This study presents the use of hydrazine as a new route for AlN ALD at temperatures as low as 177°C. AlN ALD using both ammonia and hydrazine was monitored and compared using an in-situ quartz crystal microbalance (QCM). ALD uptake curves showed 'soft' saturation behavior for the TMA half-reaction and 'hard' saturation for the hydrazine half-reaction. The AlN growth rate using hydrazine was found to be about 1.0 Å/cycle at 177°C. The ammonia reactant produced a growth rate < 0.1 Å/cycle. Different characterizations were performed on the AlN ALD films grown at 177°C. Ellipsometry and x-ray reflectivity confirmed a growth rate of about 1 Å/cycle. The AlN ALD films were determined to be amorphous by x-ray diffraction and smooth when measured by atomic force microscopy. X-ray photoelectron spectroscopy showed aluminum and nitrogen in the films and an oxide surface layer. Electrical measurements for the dielectric constant and the leakage current density were in good agreement with results from AlN CVD films. This study demonstrates the potential of hydrazine as a suitable nitrogen precursor for low temperature AlN ALD.