Nucleation of HfO2 atomic layer deposition films on chemical oxide and H-terminated Si

Abstract

HfO 2 thin films have been deposited by an atomic layer deposition (ALD) process using alternating pulses of tetrakis-ethylmethylamino hafnium and H2O precursors at 250 °C. The as-deposited films are mainly amorphous and nearly stoichiometric HfO2 (O/Hf ratio ∼1.9) with low bonded carbon content (∼3 at. %). A comparison of the nucleation stage of the films on OH- and H-terminated Si(100) surfaces has been performed using Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). We find for the initial 5–7 process cycles that the film nucleates more efficiently on the OH-terminated surface. However, after the 7th cycle both surfaces exhibit similar surface coverage, which takes about 40 cycles to reach a steady growth rate per cycle. Angle resolved XPS measurements reveal the formation of a ∼6 Å interfacial layer after four ALD cycles on the H-terminated surface and the thickness of the interfacial layer does not change substantially between the 4th and the 50th process cycles as shown by transmission electron microscopy. Although the surface coverage is comparable for both starting surfaces, film measurements performed by SE suggest that thick films deposited on H-terminated Si are ∼5% thicker than similar films on the chemical oxide surface. Atomic force microscopy (AFM) measurements reveal higher surface roughness for the films deposited in the H-terminated surface. The SE and the AFM data are consistent with higher porosity for the films on H-terminated surfaces.

Stability and Surface Reactivity of Anatase TiO2Films

“…TiO 2 films were deposited using a custom ALD reactor previously described by Hackley et al 28 The films were grown using TDMAT and H 2 O as the Ti source and oxidizing agent respectively. Base pressure in the flow tube during deposition was ∼220 mTorr and precursor pulses were typically 5-10 mTorr for TDMAT and 20 mTorr for H 2 O. Spectroscopic ellipsometry (SE) measurements using a α-SE instrument from J.…”

AlN/GaN HEMTs with high‐κ ALD HfO2 or Ta2O5 gate insulation

“…Device processing followed conventional III-N techniques. Prior to 150 and 250 nm long e-beam gate definition, the HfO 2 and Ta 2 O 5 dielectrics were deposited using a blanket ALD process in a flow type hot-wall reactor [10]. For the HfO 2 film the precursors were tetrakis ethylmethyl amino hafnium (TEMAHf) and H 2 O and the depositions were performed at 250 °C.…”

In situ synchrotron based x-ray fluorescence and scattering measurements during atomic layer deposition: Initial growth of HfO2 on Si and Ge substrates

“…The AFM results are in agreement with previous ex situ studies of the nucleation of the TEMAH/ H 2 O process on Si based substrates under similar conditions. 15 The evolution of the surface roughness during growth was studied by in situ GISAXS ͓see Fig. 2͑b͔͒.…”