Novel Thermally-Stable Hafnium and Zirconium ALD Precursors

Abstract

Topic: Advanced Processes and Materials AbstractAtomic Layer Deposition (ALD) of Hf and Zr oxide films is of considerable interest and promise for future generation Metal-Insulator-Metal (MIM) structures in memory applications. Hafnium and zirconium alkylamides such as tetrakis(ethylmethylamino) hafnium (TEMAH) and tetrakis(ethylmethylamino) zirconium (TEMAZ) are the most considered precursors. However, their relatively low thermal stability might become a drawback under heated distribution conditions that could result in vaporizer clogging or insufficient long-term stability. Moreover, these precursors may not be suitable if higher deposition temperature processes are sought.Alternative ALD precursors with improved thermal stability could be viable alternatives. Among the precursor families that could be considered (halides, alkoxides, β-diketonates, tetranitrates, etc.), metallocenes are particularly attractive. New hafnocenes -dimethyl bis(ethylcyclopentadienyl) hafnium, Hf(EtCp)2Me2, and dimethyl bis(methylcyclopentadienyl) hafnium, Hf(MeCp)2Me2 -with improved physical properties and thermal stability are studied here. The thermal behavior of these new precursors has been extensively characterized for vapor pressure, thermal stability, and evaporation kinetics.The ALD behavior of Hf(EtCp)2Me2 with O3 as coreactant was investigated at high temperature (350-400°C), an ALD deposition rate of 0.72Å/cycle was achieved. Hf(EtCp)2Me2 showed the best compromise between thermal stability, physical properties, and deposition behavior. Similar zirconocenes were als o studied: ZrCp2Me2, Zr(MeCp)2Me2, Zr(EtCp)2Me2 and Zr(EtCp)(NMe2)3.

Amidoxime-Containing Zr and Hf Atomic Layer Deposition Precursors for Metal Oxide Thin Films

“…, ( E )- N ′-hydroxy- N , N -dimethylacetimidamide (mdaoH) and ( Z )- N ′-hydroxy- N , N -dimethylpivalimidamide (tdaoH), along with their Zr and Hf homoleptic complexes, Zr­(mdao) 4 ( 1 ), Hf­(mdao) 4 ( 2 ), Zr­(tdao) 4 ( 3 ), and Hf­(tdao) 4 ( 4 ). It is well-known that the replacement of one ligand with a cyclopentadienyl (Cp) ligand enhances the thermal stability and volatility of the given precursors. , Furthermore, in the previous study, we also confirmed that the melting point decreased when a Cp ligand was introduced into the respective homoleptic solid compound to yield the corresponding heteroleptic . Therefore, it was expected that the mixed ligand systems combining amidoxime and Cp ligand would provide improved physical properties.…”

“…It is wellknown that the replacement of one ligand with a cyclopentadienyl (Cp) ligand enhances the thermal stability and volatility of the given precursors. 28,29 Furthermore, in the previous study, we also confirmed that the melting point decreased when a Cp ligand was introduced into the respective homoleptic solid compound to yield the corresponding heteroleptic. 24 Therefore, it was expected that the mixed ligand systems combining amidoxime and Cp ligand would provide improved physical properties.…”

Decomposition Characteristics of the TTIP (Tetraisopropyl Orthotitanate) Precursor for Atomic Layer Deposition

“…The thermal stability of a precursor must be discussed for a successful ALD process, and many studies have already been carried out [25][26][27][28]. However, most of the studies related to the thermal stability of precursors have measured the decomposition temperature using thermogravimetric analysis (TGA) or studied the decomposition behavior in the gas phase by using quadrupole mass spectrometry (QMS) and a quartz crystal microbalance (QCM) [29][30][31].…”

Surface Chemistry of Pentakis(dimethylamido)tantalum on Ta Surfaces

“…The focus of this manuscript is the chemistry of pentakis(dimethylamido)tantalum (PDMAT), Ta[N(CH 3 ) 2 ] 5 , on tantalum surfaces. PDMAT is one of the most common precursors used for TaN deposition. ,− The surface chemistry of PDMAT is also closely related to that of other similar precursors such as tetrakis(dimethylamido)titanium (TDMAT), Ti[N(CH 3 ) 2 ] 4 , and tetrakis(dimethylamido)hafnium (TDMAH), Hf[N(CH 3 ) 2 ] 4 , − which contain the same dimethylamido ligands, and even to that of tetrakis(methylethylamido)titanium (TEMAT), Ti[N(CH 3 )(C 2 H 5 )] 4 , − tetrakis(methylethylamido)zirconium (TEMAZ), Zr[N(CH 3 )(C 2 H 5 )] 4 , − and tetrakis(methylethylamido)hafnium (TEMAH), Hf[N(CH 3 )(C 2 H 5 )] 4 , , which have closely related amido groups.…”