ICMCTF2003 Session B9: Emerging Technologies and Critical Issues in Vapor Deposition

Friday, May 2, 2003 8:30 AM in Room Sunrise

Friday Morning

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8:30 AM B9-1 Atomic Layer Deposition Technologies for Semiconductor Applications; Hafnium Oxide and Zirconium Oxide Films for Gate Stack Stacks
J.W.H. Maes, S. Haukka, H. de Waard (ASM International N.V., The Netherlands)

There is a rapidly growing interrest to use films deposited by atomic layer deposition in semiconductor device manufacturing. In atomic layer deposition substrates are exposed alternatively to two or more highly reactive precursors pulses. Process conditions ensure that during each pulse a self-limiting surface reaction takes place that is forming one molecular layer on the surface.

Using atomic layer deposition, high quality hafnium oxide and zirconium oxide gate dielelectric films can be deposited at a temperature as low as 300°C using hafnium chloride (or zirconium chloride) and water as precursors. Due to the self-limiting nature of the surface reactions the thickness control of the films is simple (0.05 nm/cycle). With a properly selected ultrathin silicon oxide surface layer on silicon, film nucleaction is rapid and film closure takes place after less then 1 nm of deposition. Further it will be shown that during film deposition there is no subtantial oxidation of the underlying silicon which enables to make gate dielectrics with an electrical thickness below 1 nm. Leakage currents of the films are several orders of magnitudes lower than that of equivalent conventional silicon dioxide gate dielectrics.

Advanced mixed oxide layers like hafnium aluminate or hafnium silicate can be deposited through pulse sequences in which two different metal compound precursors are alternated. It is demonstrated that by adjusting the pulse sequence the composition and other physical properties of these mixed oxides can be varied and optimized. Finally, it will be shown that by atomic layer deposition films can be deposited very conformally even on extremely non-planar substrates. This is done by applying enough precursor dose to allow for full surface saturation every deposition cycle.

9:10 AM B9-3 Deposition of Oxides Using a Novel rf- Wave Resonance Plasma Source
J. Degenhardt (CCR GmbH Coating Technology, Germany); L. Kleinen (Transferstelle der Universitaet Kaiserslautern im TZO Rheinbreitbach, Germany); M. Weiler (CCR GmbH Coating Technology, Germany)
Plasma assisted chemical vapor deposition (PECVD) is a promising tool for high rate, low temperature deposition of oxide layers, even on temperature sensitive substrates like polymers. Using a wave resonant excitation mechanism in an inductively coupled rf-discharge by superimposing a weak magnetic field in the range of 1-2 mT has been proven to be a very efficient technique in the oxidation of metal organic precursors like hexamethyldisiloxane (HMDSO) to form silicon dioxide films. Due to the high degree of dissociation of 80%, and a degree of ionization of 20% accompanied by plasma densities of up to 1013 per cm3, a very efficient activation of the precursor molecules is achieved. In this study, the influence of the deposition parameters was correlated with the properties of the layers, i.e. optical and mechanical properties. It could be shown that the plasma assisted oxidation of the vaporized precursor leads to high quality silicon dioxide films which are fully oxidized and have excellent optical properties.
9:30 AM B9-4 Materials Modification with Electron Beam Generated Plasmas*
C. Muratore (US Naval Research Laboratory/ASEE Postdoctoral Research); D. Leonhardt, S.G. Walton (US Naval Research Laboratory); D.D. Blackwell (US Naval Research Laboratory/SFA, Inc.); R.F. Fernsler, R.A. Meger (US Naval Research Laboratory)

Pulsed electron beam generated plasmas exhibit temporally and spatially dependent distributions of ionized, neutral and radical species that are well-understood from Langmuir probe and mass spectrometer measurements [1, 2]. Under appropriate extrinsic conditions, the densities of desirable plasma species are large compared to those observed in conventional processing discharges. A variety of materials processing systems have been designed in an effort to explore the utility of these characteristics of beam generated plasmas for nitriding and thin film deposition applications. The nitriding experiments were performed exclusively in an electron beam generated plasma, while the deposition experiments were performed using beam generated plasmas with and without auxillary sputtering magnetrons. Experiments have been designed to understand the role of electron beam plasmas in surface modification processes. Additionally, the control of plasma chemistry observed in beam generated plasmas facilitates the development of process-structure-property relationships in materials systems. To assess and correlate the effects of intrinsic plasma characteristics on the structure and properties of materials, scanning electron microscopy, x-ray diffraction, atomic force microscopy, hardness tests, and other conventional materials characterization techniques were used.

[1] S. Walton et al., Phys. Rev. E, 65, 46412 (2002). [2] D. Leonhardt et al., J. Vac. Sci. Technol. A, 19, 1367 (2001.

*This work supported by the Office of Naval Research

9:50 AM B9-5 Homogeneous Coatings Inside Cylinders
F. Löffler, C. Siewert (Physikalisch-Technische Bundesanstalt, Germany)
The realisation of homogeneous coatings inside small cylindrical parts, e.g. pipes, is still a big challenge. It is very difficult to obtain uniform thin film properties with a PVD-process over the whole area which has to be covered by the thin film. A physical limit leads to a minimum distance between the cathode and the thin film growth zone. A pin-shaped metal cathode in combination with a specially designed outlet port for the argon gas has made it possible to deposit a thin metal film inside an aluminium pipe. The metal cathode was 4 mm in diameter, and the aluminium pipe 30 mm in length with a diameter of 12 mm. A physical vapour deposition (PVD) process was used for plating of the thin film. Under vacuum conditions, argon ions are used to evaporate the target. The metal atoms and ions are transported to the substrate surface where the growth layer is deposited. In first experiments, copper was used for the cathode. Niobium thin films were tested in a second phase. The thickness of the metal coating is approx.100 nm. The advantage of this process is a low substrate temperature and the good homogeneity of the thin film. X-ray fluorescence measurements have been carried out to measure the thickness distribution over the whole surface of the coating. The film structure has been evaluated in other investigations. .
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