Patterned deposition by plasma enhanced spatial atomic layer deposition (original) (raw)
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Journal of Vacuum Science & Technology A, 2020
In this paper, the emerging role of ionic species in plasma assisted chemical deposition processes is discussed in details for commemorating the Career of John Coburn who studied the role of ionic species in plasma etching processes forty years ago. It is shown that in both Plasma Enhanced Chemical Vapor Deposition (PECVD) and Plasma Enhanced Atomic Layer Deposition (PEALD) processes, plasma ions can play a major role in tuning a wide range of physical properties of thin films. In both processes, the possibility of extracting plasma ions with a tunable incident kinetic energy driven on the substrate surface is shown to provide a valuable additional degree of freedom in plasma processing. While a too large incident kinetic energy of plasma ions may have damaging effects linked to surface sputtering and atomic peening, a relatively low energy ion bombardment ensures a substantial improvement of thin film purity and the effective tuning of its microstructural properties. This phenomenon is attributed to the synergetic effect boosting momentum transfer and chemical reactivity among radicals and ionic plasma species which in turn modulates plasma-surface interactions. Taking advantage of these tunable physical properties opens up the way to a large array of pathways for selective deposition processes in both 2D and 3D nanoscale microstructures.
Plasma-Assisted Nanofabrication: The Potential and Challenges in Atomic Layer Deposition and Etching
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The growing need for increasingly miniaturized devices has placed high importance and demands on nanofabrication technologies with high-quality, low temperatures, and low-cost techniques. In the past few years, the development and recent advances in atomic layer deposition (ALD) processes boosted interest in their use in advanced electronic and nano/microelectromechanical systems (NEMS/MEMS) device manufacturing. In this context, non-thermal plasma (NTP) technology has been highlighted because it allowed the ALD technique to expand its process window and the fabrication of several nanomaterials at reduced temperatures, allowing thermosensitive substrates to be covered with good formability and uniformity. In this review article, we comprehensively describe how the NTP changed the ALD universe and expanded it in device fabrication for different applications. We also present an overview of the efforts and developed strategies to gather the NTP and ALD technologies with the consecutive...
Plasma-assisted atomic layer deposition : an in situ diagnostic study
2008
The method of atomic layer deposition (ALD) is considered one of the primary candidates for the uniform and conformal deposition of ultrathin films vital for the continuous miniaturization in the semiconductor industry and related high-technology markets. By the virtue of two selflimiting surface reactions, the ALD technique yields an ultimate control of film growth in the sense that a submonolayer of material is deposited per so-called ALD cycle. With established materials being at the verge of industrial implementation, efforts are continuously undertaken to optimize and develop new ALD configurations and processes. So far, the main emphasis within the field of ALD has been on the materials characterization of the films by means of ex situ analysis. The research described in this thesis aims at the development of the relatively new configuration of plasma-assisted ALD and at in situ diagnostics studies of the (plasmaassisted) ALD processes. In plasma-assisted ALD, a plasma is used...
Applications of plasma-enhanced metalorganic chemical vapor deposition
Journal of Crystal Growth, 2020
The use of plasma enhancement for growth of III-V compound semiconductor materials by metalorganic chemical vapor deposition (MOCVD) is examined, to improve control of microstructure, develop understanding of the underlying growth mechanisms, and expand the range of materials combinations for photovoltaic and solidstate lighting applications. Whereas plasma is commonly used with group-IV materials, such as silicon, few studies have examined the impact of plasma-enhanced MOCVD (PE-MOCVD) for III-V materials growth. PE-MOCVD provides improved decomposition of metalorganic precursors, which is driven by hydrogen plasma to augment hydride reactions and thermal pyrolysis, but plasma generation requires low reactor pressure. We have demonstrated elemental Al films grown by PE-MOCVD, which show distinct crystallographic texturing, and assume epitaxial microstructure upon post-growth annealing. We also demonstrate PE-MOCVD of GaAs at temperatures as low as 300°C. With increasing radio-frequency power, the GaAs growth rate shows a transition from power limited to mass-transport limited. PE-MOCVD grown Ga 0.5 In 0.5 P shows no detectable spontaneous atomic ordering, which offers a mechanism to form order/disorder unicompositional heterostructures, without temperature change or impurity incorporation. In its current implementation, PE-MOCVD grown films have shown microstructural degradation, that we attribute to direct plasma exposure during growth. Improvements in the system design and growth sequences are at the focus of ongoing efforts.
Conformality of Plasma-Assisted ALD: Physical Processes and Modeling
Journal of The Electrochemical Society, 2010
For plasma-assisted atomic layer deposition ͑ALD͒, reaching conformal deposition in high aspect ratio structures is less straightforward than for thermal ALD due to surface recombination loss of plasma radicals. To obtain a detailed insight into the consequences of this additional radical loss, the physical processes in plasma-assisted ALD affecting conformality were identified and investigated through Monte Carlo simulations. The conformality was dictated by the recombination probability r, the reaction probability s, and the diffusion rate of particles. When recombination losses play a role, the saturation dose depended strongly on the value of r. For the deposition profiles, a minimum at the bottom of trench structures was observed ͑before reaching saturation͒, which was more pronounced with larger values of r. In turn, three deposition regimes could be identified, i.e., a reaction-limited regime, a diffusion-limited regime, and a new regime that is recombination-limited. For low values of r, conformal deposition in high aspect ratio structures can still be achieved, as observed for several metal oxides, even for aspect ratios as large as 30. For high surface recombination loss probabilities, as appears to be the case for many metals, achieving a reasonable conformality becomes challenging, especially for aspect ratios Ͼ10.
Plasma Directed Assembly: Process Issues, Materials and Applications
2013
,gr The modern trend in nanofabrication is the use of self or directed assembly methods to form periodic or semi-periodic patterns in the nanoscale. Block copolymer lithography and colloidal lithography are used mostly to create these patterns. Our group [1, 2] has shown that oxygen plasma can direct the formation of organized nanodots on the surface of PMMA films (Fig. 1) and then transfer the pattern to a subsequent Silicon substrate.
In situ reaction mechanism studies of plasma-assisted atomic layer deposition of Al2O3
Applied Physics Letters, 2006
Reaction mechanisms during plasma-assisted atomic layer deposition ͑ALD͒ of Al 2 O 3 from Al͑CH 3 ͒ 3 and O 2 plasma were studied by time-resolved quartz crystal microbalance measurements, mass spectrometry, and optical emission spectroscopy. Al͑CH 3 ͒ 3 chemisorption on the oxide surface after the plasma pulse releases CH 4 products while from the detection of CO, CO 2 , and H 2 O in the O 2 plasma it is established that surface-CH 3 groups are predominantly removed by O radical-driven combustionlike reactions. Also a second pathway exists for-CH 3 removal driven by H 2 O generated in this plasma step. These reaction pathways are expected to be generic for plasma-assisted ALD of oxides from metal organic precursors.
Improvement in processing of micro and nano structure fabrication using O2 plasma
2011
Plasma has frequently been used by the industry as a last step surface preparation technique in an otherwise predominant wet-etched process. Recent research of the chemistry of plasma led to a great understanding of plasma processes. It is by controlling the plasma conditions and gas mixtures, ultra-fast plasma cleaning and etching is possible. With enhanced organic removal rates, plasma processes become more desirable as an environmentally sound alternative to traditional solvent or acid dominated process, not only as a cleaning tool, but also as a patterning and machining tool. In this paper, improvement in the processing of nanogap fabrication using O 2 plasma is discussed including the parameters for PR patterning with two times limited in the O 2 plasma process. For applications that have not been possible with limited usefulness, plasma processes are now approaching the realm of possibility. We introduce this work to fabricate and characterize the nanogap device fabrication using O 2 plasma technique for biosensor fabrication. In this review, two masks designs are proposed. The first mask is for the lateral nanogap and the second mask is for a gold pad electrode pattern, and the lateral nanogap is introduced in the fabrication process using silicon, and gold as an electrode. Conventional photolithography technique is used to fabricate this nanogap (NG) based on the plasma etching technique. The increase in etching time when we apply the O 2 plasma means an increase in the amount of etching, while in the case of reducing the time of etching means reducing the amount of etching, as shown in the results.
Atomic layer deposition (ALD): from precursors to thin film structures
The principles of the atomic layer deposition (ALD) method are presented emphasizing the importance of precursor and surface chemistry. With a proper adjustment of the experimental conditions, i.e. temperatures and pulsing times, the growth proceeds via saturative steps. Selected recent ALD processes developed for films used in microelectronics are described as examples. These include deposition of oxide films for dielectrics, and nitride and metal films for metallizations. The use of a plasma source to form radicals is expanding the selection of ALD films to metals. Plasma-enhanced ALD also facilitates the deposition of nitride films at low temperatures. ᮊ