[Zr(NEtMe)₂(guan-NEtMe)₂] as a Novel Atomic Layer Deposition Precursor: ZrO₂Film Growth and Mechanistic Studies

Abstract

Zr(NEtMe) 2 (guan-NEtMe 2 ) 2 ], a recently developed compound, was investigated as a novel precursor for the atomic layer deposition (ALD) of ZrO 2 . With water as the oxygen source, the growth rate remained constant over a wide temperature range, whereas with ozone the growth rate increased steadily with deposition temperature. Both ALD processes were successfully developed: the characteristic self-limiting ALD growth mode was confirmed at 300 °C. The growth rates were exceptionally high, 0.9 and 1.15 Å/cycle with water and ozone, respectively. X-ray diffraction (XRD) indicated that the films were deposited in the high-permittivity cubic phase, even when grown at temperatures as low as 250 °C. Compositional analysis performed by means of X-ray photoelectron spectroscopy (XPS) demonstrated low carbon and nitrogen contamination (<2 at. % when deposited with ozone). The films presented low root-mean-square (rms) roughness, below 5% of the film thickness, as well as excellent step coverage and conformality on 30:1 aspect ratio trench structures. Dielectric characterization was performed on ZrO 2 metal−insulator−metal (MIM) capacitors and demonstrated high permittivity and low leakage current, as well as good stability of the capacitance. The ALD reaction mechanism was studied in situ: adsorption of the precursor through reaction of the two guan-NEtMe 2 ligands with the surface −OD groups was confirmed by the quartz crystal microbalance (QCM) and quadrupole mass spectrometric (QMS) results.

Atmospheric Pressure Plasma Enhanced Spatial ALD of ZrO2for Low-Temperature, Large-Area Applications

“…The solid line represents the empirical law E bd 2 ε r = constant, with the constant being ∼20. 38 Our data for sALD ZrO 2 lie on the experimentally observed best-can-do line and match previously reported data for zirconium oxide grown by means of (PE)ALD, 5,34,35,52,55,56 reactive sputtering, 57 sol-gel, 58 spraypyrolysis 59 depositions.…”

Atomic Layer Deposition of TiO2 and ZrO2 Thin Films Using Heteroleptic Guanidinate Precursors

“…The existence of an ALD temperature window is, however, neither indicative of nor necessary for a process to exhibit self‐limiting growth, but allows for a more robust process as small changes in the temperature do not affect the growth rate of the film. Wide ALD windows have been seen earlier in several other processes employing guanidinate precursors as well …”

“…In a previous study, we investigated the growth of ZrO 2 using bis‐guanidinate [Zr(NEtMe) 2 (guan‐NEtMe) 2 ] as the zirconium precursor . Except for the precursor itself, the experimental set‐up and deposition parameters were strictly identical to the present study.…”

“…In addition, many guanidinate complexes have good volatility and high thermal stability . So far, guanidinate compounds have been introduced as either homo‐ or heteroleptic ALD precursors in the deposition of high‐ k oxides (TiO 2 , ZrO 2 , HfO 2 , Gd 2 O 3 , Dy 2 O 3 ). In addition, they have been used in the metal‐organic (MO)CVD of rare‐earth oxides (Gd, Dy) as well as Gd, Ta, and W nitrides.…”

“…In this study, we investigate the water and ozone processes of two novel heteroleptic monoguanidinate precursors, namely tris(ethylmethylamido)( N , N ′‐diisopropyl‐2‐ethylmethylamidoguanidinato)M IV ([M(NEtMe) 3 (guan‐NEtMe)]), where M is either Ti IV or Zr IV . The ALD process characteristics of the precursors and the properties of the deposited films are subsequently compared with earlier studies, with a special emphasis on our earlier investigation on a heteroleptic zirconium bis‐guanidinate precursor [Zr(NEtMe) 2 (guan‐NEtMe) 2 ]. Using the notation introduced above, in the present study a precursor ZrX 3 Y is investigated (X and Y being the –NEtMe and –guan‐NEtMe ligands, respectively) while the process qualities of ZrX 4 and ZrX 2 Y 2 have been examined in previous studies …”