Next generation MOx active layers for AM-TFT display backplanes deposited
by static large area PVD technology with rotary cathode technology
Marcus Bender, Hyun Chan Park, Ajay Sampath Bhoolokam, Andreas Klöppel, Markus Hanika
Applied Materials GmbH & Co. KG, Alzenau, Germany
Active matrix (AM) driven displays traditionally make use of a-Si as active layer in the
thin film transistor (TFT). Recently trends to larger devices with higher refresh rates
and higher resolutions have lead to the requirement of TFTs with higher mobilities in
order to provide appropriate driving capabilities. Metal oxides such as Indium-
Gallium-Zinc-Oxide (IGZO) have widely been studied as new active layer replacing
a-Si for this application with the result of first implementations of metal oxide driven
devices readily to be found on the market.
Applied Materials has been developing a static deposition process for IGZO using
the PiVotTM Gen8.5 array coater. Basic demand for the active layer deposition is the
combination of excellent uniformity, short deposition time, and electronic properties
of the deposited layer. The PiVotTM array coater makes use of a unique array of
rotary targets. Rotary target technology enables very high target utilization combined
with high process stability due to the inherent benefit of omitting redeposition zones
on the target surface. Re-directing the flux of sputtered material as well as charged
particles originating in the discharge by Magnet wobble is key to achieving uniform
and high quality layers. It is important to note that uniformity in this context is not
limited to film thickness or film resistance but includes also electronic properties, film
morphology and others. Thus, rotary target technology helps improving quality and
productivity as well as decreasing production cost for the display manufacturers.
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