AVS 58th Annual International Symposium and Exhibition
    Transparent Conductors and Printable Electronics Focus Topic Thursday Sessions
       Session TC+AS+EM-ThM

Paper TC+AS+EM-ThM6
Laboratory and Production-Scale Low-Temperature Transparent Conducting Oxide Deposition

Thursday, November 3, 2011, 9:40 am, Room 106

Session: Transparent / Printable Electronics Part 1
Presenter: Eithan Ritz, University of Illinois at Urbana Champaign
Authors: E. Ritz, University of Illinois at Urbana Champaign
G.B. Rayner, Kurt J. Lesker Company
D. Andruczyk, University of Illinois at Urbana Champaign
T. Dockstader, Kurt J. Lesker Company
D.N. Ruzic, University of Illinois at Urbana Champaign
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Transparent conducting oxides (TCOs) are a class of materials that are becoming increasingly ingrained in our daily lives due to their use in electronic displays and mobile devices. There is a strong need to develop an economical deposition technique that allows for high transparency films with high electrical conductivity while replacing costly materials such as Indium Tin Oxide (ITO) with alternatives such as Aluminum-doped Zinc Oxide (AZO). In addition, a low-temperature deposition method would allow creation of TCOs on flexible plastic substrates, such as polyethylene terephthalate (PET). By using a dual DC magnetron system with a secondary RF antenna running at 13.56 MHz, a process has been developed that can deposit TCO films without significantly heating the substrate while maintaining high transmission and electrical properties. This capability has been demonstrated on a small-scale experimental setup utilizing 3-inch diameter circular magnetrons as well as a prototype production-scale chamber operating with 18x3.5 inch rectangular mangetrons aimed at flexible photovoltaic manufacturing. Using an immersed inductive RF antenna, ionization fraction can be increased to over 80%, measured by a gridded energy analyzer, and plasma density increased by an order of magnitude from 1010 cm-3 to 1011 cm-3, as measured by Langmuir probe. The secondary plasma deposits energy in the film without heating the substrate above 100°C while still achieving film resistivity on the order of 10-3-10-4 Ohm-cm (measured by four-point probe method) and transparency of greater than 90% in the visible wavelengths (measured by spectrophotometry.) Adjusting the RF power (0-1000W) and the oxygen content (0-5%) in the plasma enables the ability to tune the film transparency and conductivity to desired levels. Crystal formation of films analyzed by x-ray diffraction (XRD) and elemental composition determined by x-ray photoelectron spectroscopy (XPS).