Enhanced initial growth of atomic-layer-deposited metal oxides on hydrogen-terminated silicon

Abstract

A route is presented for activation of hydrogen-terminated Si(100) prior to atomic layer deposition. It is based on our discovery from in situ infrared spectroscopy that organometallic precursors can effectively initiate oxide growth. Narrow nuclear resonance profiling and Rutherford backscattering spectrometry show that surface functionalization by pre-exposure to 108 Langmuir trimethylaluminum at 300 °C leads to enhanced nucleation and to nearly linear growth kinetics of the high-permittivity gate dielectrics aluminum oxide and hafnium oxide.

Incomplete elimination of precursor ligands during atomic layer deposition of zinc-oxide, tin-oxide, and zinc-tin-oxide

“…. 27 It should be emphasized that the measurement procedure ( Fig. 3(a)) is not representative of the typical conditions employed during ALD, as the surface is exposed to a high pressure of H 2 O (4 Torr for ∼30 s, corresponding to ∼10 8 L) during the closure of the valve between the chamber and the pump which is not accounted for in the above exposure estimate.…”

High dielectric constant oxides

“…This limits the ultimate lowest EOT that ALD can presently achieve. However, the development of ALD precursors which do nucleate on H-terminated Si and different processing strategies will overcome this obstacle when needed [33,34].…”

Compositional stability of hafnium aluminates thin films deposited on Si by atomic layer deposition

“…A convenient approach for depositing such films ͑oxides and mixed oxides͒ is the atomic layer deposition ͑ALD͒ technique, where self-saturating surface chemical reactions are employed. This approach 5,6 has been successfully applied to control chemical reactions at the Si/ high-k and high-k / gate electrode interfaces, as well as to obtain ͑HfO 2 ͒ x ͑Al 2 O 3 ͒ 1−x structures retaining sufficiently high dielectric constant and remaining amorphous up to high processing temperatures. Metastable defect configurations owing to the low-temperature film deposition process can be suppressed by postdeposition annealing.…”

“…The 27 Al͑p , ␥͒ 28 Si nuclear reaction around the resonance in the cross section curve at 992 keV was used for that purpose as performed in Ref. 5. These methods give precisions for Hf, Al and O areal densities of about 3%, 10% and 10%, respectively.…”

“…[3][4][5] A good tradeoff between the characteristics of these two materials 1, [6][7][8][9][10][11] can be achieved by forming ͑HfO 2 ͒ x ͑Al 2 O 3 ͒ 1−x mixed oxides, either homogeneous in composition or in nanolaminated structures. A convenient approach for depositing such films ͑oxides and mixed oxides͒ is the atomic layer deposition ͑ALD͒ technique, where self-saturating surface chemical reactions are employed.…”