ChemInform Abstract: Atomic Layer Deposition of Tantalum Oxide Thin Films from Iodide Precursor.

Kukli, Kaupo; Aarik, Jaan; Aidla, Aleks; Forsgren, Katarina; Sundqvist, Jonas; Haårsta, Anders; Uustare, Teet; Maendar, Hugo; Kiisler, Alma‐Asta

doi:10.1002/chin.200119205

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“…Considering the ALD growth of Nb 2 O 5 , 20−22 the only successful ALD processes reported until recently were Nb(OC 2 H 5 ) 5 /H 2 O 23 and NbI 5 /O 2. 24 Although for Ta 2 O 5 deposition, in addition to Ta(OC 2 H 5 ) 5 25−27 and TaI 5 , 28,29 other processes already exist, 30,31 including some based on alkylamides precursor 32,33 and amidinates. 34−36 Recently, our group reported the use of three novel precursors for water and ozone based thermal ALD processes, among which t BuN=Nb(NEt 2 ) 3 and t BuN=Ta(NEt 2 ) 3 demonstrated the most significant results in terms of growth rate and thermal stability.…”

Section: ■ Introductionmentioning

confidence: 99%

In SituReaction Mechanism Studies on the New^tBuN=M(NEt₂)₃-Water and^tBuN=M(NEt₂)₃- Ozone (M = Nb,Ta) Atomic Layer Deposition Processes

et al. 2012

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In this work, quartz crystal microbalance (QCM) and quadrupole mass spectrometry (QMS) have been used for in situ investigations of the D 2 O and ozone processes at 250°C for t BuN=Nb(NEt 2 ) 3 and t BuN=Ta(NEt 2 ) 3 . In the D 2 O processes, the ligand exchange reaction is demonstrated by the formation of D 2 N t Bu and DNEt 2 as byproduct. For t BuN=Nb(NEt 2 ) 3 , one out of three -NEt 2 ligands is exchanged during the precursor pulse, whereas for t BuN=Ta(NEt 2 ) 3 , it is 1.7 -NEt 2 ligands and 0.3 =N t Bu ligand that are exchanged during the t BuN=Ta(NEt 2 ) 3 pulse. This difference in the reaction mechanism of the two structurally similar precursors can be explained by the differences in their bond polarities as shown by our quantum chemical calculations. Regarding the ozone processes, QCM results point to a molecular adsorption of t BuN=Nb(NEt 2 ) 3 and an exchange of at least two ligands for t BuN=Ta(NEt 2 ) 3 . QMS indicates a typical ozone combustion byproduct, such as CO 2 (m/z = 44), CO (m/z = 28), H 2 O (m/ z = 18), and NO (m/z = 30) or N 2 O (m/z = 44, 30). A major fragment of both types of ligands (m/z = 58) is also observed. Precise quantification of these byproduct is rendered impossible due to overlapping of different species with the same m/z value. However, careful examination of the data reveals general information on the different contributions to the signal. KEYWORDS: atomic layer deposition (ALD), mass spectrometry, quartz crystal microbalance (QCM), niobium oxide, tantalum oxide ■ INTRODUCTIONAtomic layer deposition (ALD) is a unique chemical gas phase method for depositing thin films. 1−3 In ALD the precursors are alternately pulsed into the reactor and separated by inert carrier gas purging. The precursors saturate the surface one at a time, forming at most monolayers that induce a self-limiting growth mechanism. Consequently, the thickness of the growing film is accurately controlled, and the films exhibit excellent uniformity and conformality. Understanding the mechanisms of reactions occurring at each step of an ALD deposition can help to control and optimize the growth processes and accelerate the development of new ALD processes and precursors. Most commonly, ex situ analyses are performed: the films are first grown and their characteristics are examined separately. However, the development of in situ measurements has become an important approach for mechanistic studies in the past decade. Several techniques such as FT-IR, ellipsometry, and in our case quartz crystal microbalance (QCM) and quadrupole mass spectrometry (QMS) 4−8 are used for in situ investigations. The QCM indicates the mass changes of the growing film, while the QMS follows the composition of the gas phase inside the reaction chamber. The identification of gaseous byproduct and the recorded mass changes during the pulses of the different precursors provide direct information on the reaction mechanism.Nb 2 O 5 and Ta 2 O 5 are high-permittivity materials with potential thin film applications in DRAM devices, 9,10 ca...

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Section: ■ Introductionmentioning

confidence: 99%

In SituReaction Mechanism Studies on the New^tBuN=M(NEt₂)₃-Water and^tBuN=M(NEt₂)₃- Ozone (M = Nb,Ta) Atomic Layer Deposition Processes

et al. 2012

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ChemInform Abstract: Atomic Layer Deposition of Tantalum Oxide Thin Films from Iodide Precursor.

Cited by 1 publication

References 1 publication

In SituReaction Mechanism Studies on the New^tBuN=M(NEt₂)₃-Water and^tBuN=M(NEt₂)₃- Ozone (M = Nb,Ta) Atomic Layer Deposition Processes

In SituReaction Mechanism Studies on the New^tBuN=M(NEt₂)₃-Water and^tBuN=M(NEt₂)₃- Ozone (M = Nb,Ta) Atomic Layer Deposition Processes

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ChemInform Abstract: Atomic Layer Deposition of Tantalum Oxide Thin Films from Iodide Precursor.

Cited by 1 publication

References 1 publication

In SituReaction Mechanism Studies on the NewtBuN=M(NEt2)3-Water andtBuN=M(NEt2)3- Ozone (M = Nb,Ta) Atomic Layer Deposition Processes

In SituReaction Mechanism Studies on the NewtBuN=M(NEt2)3-Water andtBuN=M(NEt2)3- Ozone (M = Nb,Ta) Atomic Layer Deposition Processes

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In SituReaction Mechanism Studies on the New^tBuN=M(NEt₂)₃-Water and^tBuN=M(NEt₂)₃- Ozone (M = Nb,Ta) Atomic Layer Deposition Processes

In SituReaction Mechanism Studies on the New^tBuN=M(NEt₂)₃-Water and^tBuN=M(NEt₂)₃- Ozone (M = Nb,Ta) Atomic Layer Deposition Processes