Sanna Yliniemi, Wei-Min Li, Tero Pilvi, Timo Malinen, Marko Pudas



Sanna Yliniemi, Wei-Min Li, Tero Pilvi, Timo Malinen, Marko Pudas
Sanna Yliniemi, Wei-Min Li, Tero Pilvi, Timo Malinen, Marko Pudas, Juhana
Picosun Oy, Tietotie 3, FI-02150 Espoo, Finland, [email protected]
Atomic Layer
Deposition (ALD) in
MEMS Applications
Top: Highly uniform and conformal TiN on a Si device
wafer, deposited in a PICOSUN™ R-200 ALD reactor.
SEM-micrographs, clockwise from top left: Ultra-high-k
dielectric SrTiO3 film on Si trench wafer (picture credit
Prof. M. Ritala, Univ. of Helsinki) and ~100 % conformal
ZnO:Al in a deep trench of AR 60:1 (pictures by VTT
Technical Research Centre of Finland).
• Conformal, electrically insulating
layers deposited at low
• Etch masks, etch stop layers
• Conductive seed layers for plating
• Conformal, thermally conductive
• Hydrophobic layers to reduce
• Hermetically sealed coatings
• Biocompatible coatings
• Closing of nanoscale pores
• Optical layers (reflective, antireflective, black absorbers)
• Layers reducing frictional wear
• Charge dissipative layers
• Diffusion barrier, adhesion and
seed layers in through-silicon vias
On the left: High-Q mechanical
silicon oscillator (O. Hahtela et. al.,
J. Micromech. Microeng. 17 (2007)
737). On the right: ALD-enabled
MEMS microengine (T. M. Mayer
et. al., Appl. Phys. Lett. 82 (2003)
On the left: MEMS actuator. On the right: Large force electrostatic MEMS
comb drive. ALD Al2O3 and ZnO proposed for use as charge dissipative
layers (C. F. Herrnlann et. al., Sens. Actuators A: Phys. 135 (2007) 262).
On the left: 3D micromechanical compass (Kyynäräinen et. al., Sensor
Letters 5 (2007) 1). On the right: ALD-enabled fluorine dry etch barrier
(trenches in Si etched in the ICP after patterning Al2O3 by lift-off with 2
µm resist mask). Pictures by VTT Technical Research Centre of Finland.
PICOSUN – Pioneers of ALD
• ALD: Chemical vapor based coating method of ultra-thin, 100 %
uniform, conformal, crack-, defect- and pinhole-free thin films
of high chemical and structural purity
• Film formation based on self-limiting, self-controlled gas-solid
chemical adsorption reactions on the surface
• Depositable materials range from basic oxides, nitrides,
sulphides, fluorides to pure metals (incl. noble ones),
polymers, graded/mixed/doped layers and nanolaminates with
possibility to tailor the layers’ properties on molecular level
• Possible to coat not only Si wafers but 3D objects, throughporous and powderous samples
• PICOSUN has pioneering experience in the field of ALD since
the invention of the technology in the early ´70’s
• PICOSUN develops and manufactures state-of-the-art ALD
systems with unparalleled knowhow, vision and expertise in
the field
• Today, PICOSUN™ ALD systems are in daily use in frontline
industries and research organizations on four continents
The work has been performed in EPAMO (ref. 270692-2) project, which is funded by public authorities of participant countries as well as
by the ENIAC Joint Undertaking.

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