Papers by Matthias Albert
Journal of Vacuum Science & Technology A
Understanding the role of rf-power on AlN film properties in hollow-cathode plasma-assisted atomi... more Understanding the role of rf-power on AlN film properties in hollow-cathode plasma-assisted atomic layer deposition
Microelectronic Engineering
Materials (Basel, Switzerland), Jan 27, 2018
Graphene has been proposed as the current controlling element of vertical transport in heterojunc... more Graphene has been proposed as the current controlling element of vertical transport in heterojunction transistors, as it could potentially achieve high operation frequencies due to its metallic character and 2D nature. Simulations of graphene acting as a thermionic barrier between the transport of two semiconductor layers have shown cut-off frequencies larger than 1 THz. Furthermore, the use of n-doped amorphous silicon, (n)-a-Si:H, as the semiconductor for this approach could enable flexible electronics with high cutoff frequencies. In this work, we fabricated a vertical structure on a rigid substrate where graphene is embedded between two differently doped (n)-a-Si:H layers deposited by very high frequency (140 MHz) plasma-enhanced chemical vapor deposition. The operation of this heterojunction structure is investigated by the two diode-like interfaces by means of temperature dependent current-voltage characterization, followed by the electrical characterization in a three-termina...
Langmuir, 2016
We present an optimized approach for the deposition of Al 2 O 3 (as a model secondary material) c... more We present an optimized approach for the deposition of Al 2 O 3 (as a model secondary material) coating into a high aspect ratio (≈180) anodic TiO 2 nanotube layers using atomic layer deposition (ALD) process. In order to study the influence of the diffusion of the Al 2 O 3 precursors on the resulting coating thickness, ALD processes with different exposure times (i.e. 0.5, 2, 5 and 10 sec) of the trimethylaluminium (TMA) precursor were performed. Uniform coating of the nanotube interiors was achieved with longer exposure times (5 and 10 sec), as verified by
Vakuum in Forschung Und Praxis, 2008
ACS applied materials & interfaces, Jan 30, 2015
The water vapor barrier properties of low-temperature atomic layer deposited (ALD) AlOx thin-film... more The water vapor barrier properties of low-temperature atomic layer deposited (ALD) AlOx thin-films are observed to be unstable if exposed directly to high or even ambient relative humidities. Upon exposure to humid atmospheres, their apparent barrier breaks down and their water vapor transmission rates (WVTR), measured by electrical calcium tests, deteriorate by several orders of magnitude. These changes are accompanied by surface roughening beyond the original thickness, observed by atomic force microscopy. X-ray reflectivity investigations show a strong decrease in density caused by only 5 min storage in a 38 °C, 90% relative humidity climate. We show that barrier stabilities required for device applications can be achieved by protection layers which prevent the direct contact of water condensing on the surface, i.e., the sensitive ALD barrier. Nine different protection layers of either ALD materials or polymers are tested on the barriers. Although ALD materials prove to be ineffe...
Micro- and nanofabrication of integrated circuits requires highly reliable and reproducible proce... more Micro- and nanofabrication of integrated circuits requires highly reliable and reproducible processing techniques. The application of a strict statistical process control is not any more sufficient in many sensitive parts of the process sequence. Intrinsic variations of parameters in pre processing steps have to be actively considered in the performance of the related post processing steps. A prerequisite for the practicability of this “advanced process control” (APC) concept is a close, - in best case in-situ monitoring of the processing performance. Atomic layer deposition is a relatively novel technology for the manufacturing of integrated circuits. It is essential, wherever ultra thin films with high conformity are required. In the development of their manufacturing tools, equipment makers have addressed issues like high throughput and versatility of materials, but not much attention was spent to the monitoring of the ALD process. Of course, the process parameters like susceptor...
ALD (atomic layer deposition) is a CVD (chemical vapour deposition) method, growing single layers... more ALD (atomic layer deposition) is a CVD (chemical vapour deposition) method, growing single layers of inorganic materials with less than a tenth of a nanometer thickness onto an initial substrate. Therefore, at least two vaporised precursors are alternately pulsed into the reaction chamber, one at a time, and separated by purging or evacuating pulses. Hence, the precursors can ideally react only at the substrate surface in a chemically saturated way; and a fixed amount of film material is deposited with every cyclic recurrence of these self-limiting gas-solid reactions, until the desired film thickness has been achieved. [1-3] While the ALD process modifies (not only) the chemical composition of the surface through material deposition, these changes can be observed by in-situ SE (spectroscopic ellipsometry), which is a highly surface sensitive measurement technique. In this work, we investigated the thermal activated ALD of ruthenium and ruthenium oxide from ECPR, [(ethylcyclopentadi...
2011 Semiconductor Conference Dresden, 2011
ABSTRACT Atomic layer deposition (ALD) is the most advanced technique for the fabrication of ultr... more ABSTRACT Atomic layer deposition (ALD) is the most advanced technique for the fabrication of ultra-thin conformal films. To yield high quality films, the knowledge of chemical reactions and interactions between the substrate surface and the precursors is becoming increasingly important, especially within the very first ALD cycles. In this work, the ALD process of aluminum oxide with trimethylaluminum (TMA) and water is studied by using X-ray photoelectron spectroscopy (XPS) without vacuum break. This allows the investigation of the initial gaseous-solid-reactions, i. e. the chemisorption mechanism of the precursor molecules, with sub-monolayer resolution. The results show the ligand exchange during the ALD reactions and the dependence of the growth mode on the presence of hydroxyl groups and oxygen as adsorption sites on the substrate surface.
Vakuum in Forschung und Praxis, 2008
Zusammenfassung Der charakteristische selbst begrenzende Wachstumsmechanismus der Atomlagenabsche... more Zusammenfassung Der charakteristische selbst begrenzende Wachstumsmechanismus der Atomlagenabscheidung (ALD) ermöglicht die Kontrolle der Schichtdicken im atomaren Bereich und erlaubt Beschichtungen komplexer Oberflächen. Diese Eigenschaft macht die ALD zu einer vielversprechenden Technik für die zukünftige Mikro-und Nanotechnologie. Der Schlüssel für die ALD ist die Precursorchemie.
Ruthenium and its conductive dioxide are promising candidates as electrodes in MIM (metal-insulat... more Ruthenium and its conductive dioxide are promising candidates as electrodes in MIM (metal-insulator-metal) capacitors with high-k dielectrics of next generation DRAM (dynamic random access memory) devices, as metal-gate electrodes in pMOS-Transistors with high-k dielectrics, and as seed layer for direct electrochemical plating of copper interconnects. In this work, ruthenium and ruthenium dioxide films were grown from ECPR, [(ethylcyclopentadienyl)-(pyrrolyl)ruthenium(II)], and molecular oxygen within a top injection ALD 300 reactor (FHR Anlagenbau, Ltd., Ottendorf-Okrilla/ Germany), which is elsewhere described in more detail. [1] Film growth was monitored on the as-deposited film as well as the initial substrate surface by in-situ and real-time SE (spectroscopic ellipsometry), using a J. A. Woollam Co., Inc. M-2000 ® RCE (rotating compensator ellipsometer) under a 64° angle of incidence and within a 0.73 to 4.96 eV spectral range. SE in RCE configuration measures the ellipsometric...
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Papers by Matthias Albert