The NNT 2005 was held in Nara Japan in late October. The conference continues to grow in size and attracts a
very strong set of imprint papers. The meeting recognized the 10 year anniversary of Stephen Chou's
breakthrough publication on nanoimprint. A few highlights (highly subjective) include;
- Transfer imprint to create complex structures such as bridges with difficult materials such as polyimide.
- Combined molding and transfer to create complex topolgies for cell growth.
- 2 layer PDMS molds that conform without distortion
- Step and repeat on 1 x 1 meter glass
- Very short imprint cycle times - 1-10 secs for thermal embossing of thick films , 7 secs for UV drop
dispense.
- Thin templates for large area imprints.
APPLICATIONS
Bio
A group from Georgia Tech evaluated cell growth on an array of grooves crossed by chemical lines and showed
how cell growth can be affected by both factors (Charest 2005) . A direct illustration of the power of imprint and
chemical transfer in combination. Textured polystyrene as a substrate was shown by Hitachi (Kuwabara 2005)
An ITRI team used imprinted gratings in a protein microarray to improve detection (Ho 2005)
The Lund team updated progress on molecular motors (Montelius 2005), and nerve growth (Carleberg 2005)
Materials
Imprint was used to neucleate recrystallization of polysilicon – a trick of great interest in LCD manufacture
Devices
Mike Lercel from Sematech emphasized the challenge of defect density in molds for integrated circuit
applications. The Willson group at U Texas showed results for via chains made by a single step imprint of via
and interconnect. This is one of the best early insertion paths to imprint in integrated circuits.
The HP team showed results for a 17 nm molecular memory.
Optics and Optical Devices
The most significant news was from Omron who showed results for their step and repeat system that will handle
1 meter on a side glass, and is being used for making backlights with complex 2 level structures. (Lee 2005 and
Okuno 2005)
Storage
Ovionic disclosed results for thermal embossing of Blue ray disks in less than 10 secs. They emphasized how
imprint time is increased as soon as the imprint is done on a film on a rigid substrate rather than a thick film.
MOLDS
Progress using commercial mask equipment was reported by Toppan (Fukigami 2005), defect detection using a
new e beam inspection tool from Nanogeometry research by (Resnick 2005-1). A 30 nm pitch mold was
fabricated by HP using frequency doubling edge lithography (Yu 2005)
Progress with a number of different mask materials was reported; HSQ (Kawamori 2005), diamond like carbon
(Lee 2005) and (Takahashi 2005), Ni-Fi alloys (Lee 2005-1), single layer PDMS stamps (Jo 2005) and polymers
(Kwawaguchi 2005) and (Himmelberger 2005).
One of the most interesting developments was the use of a 2 layer PDMS mold with a higher modulus PDMS
layer to reduce mold distortion (Plachetka 2005).
Mold release developments included plasma treatment of polymer templates, adding a degradable release layer
(Fuji 2005), silane treatments on modified Ni molds (Maeng 2005).
IMPRINT MATERIALS
A 2 layer imprint material stack for improved material strength was reported as well as using prexposure to fine
tune material properties.
PROCESS
Results of AFM and scatterometry of imprint patterns were discussed (Igaki 2005) and (Perret 2005).
Georgia Tech showed results for a simulation of imprint (Rowland 2005).
Transfer
Transfer imprint was one of the areas with the largest number of creative reports.
IBM described self assembly of spheres on the mold followed by transfer (Kraus 2005).
Transfer of 2 sided layers by CNRC (Drogoff 2005), Singapore Institute of Materials (Low 2005), Glasgow
(Senuarine 2005) and Osaka Prefecture University (Nakajima 2005).
New materials were transferred including polyimide (Pai 2005), HSQ (Nakamatsu 2005), negative resist
(Kehagias 2005).
Transfer improvements were described such as adhesion by heating the substrate (Nishihata 2005) and
releasing from the mold using a laser (Drogoff 2005)
UV and Thermal - Processes for high aspect ratio features by UV (Wissen 2005) and thermal imprint.
TOOLS
Step and repeat - Drop dispense
A 7 second fill time was reported by Molecular Imprints, along with sub 50m nm align, and sub 0.1 random
defects per squ cm. The also showed fixed defect count of 12 per squ cm, that had been reduced over 100 x
during the fabrication of just 3 templates (Schumaker 2005). Inspection of molds was also reported (Resnick
2005-1).
KIMM showed that very small drops leads to very thin residual layers, and that thin substrates could be distorted if
the drop spacing was too large (Kim 2005).
Air bubble formation in drop dispense was described by (Liang 2005) the Princeton U team, and a solution using
inert gas was shown by MII (Schumaker 2005).
Step and Repeat - spin on
AIST showed a new open frame stage design to improve conformality of wafer and provide an easier
implementation of align (Hiroshima 2005).
Early results for the Suss S&R tool at VTT were reported by (Ahopelto 2005).
Whole wafer tools
The use of thin templates was reported by VTT (Ahopelto 2005), and Technical University of Denmark (Pederson
2005).
MII showed that drop dispense can be used in conjunction with thin templates to imprint on non flat 2 “ wafers
and hard disks.
Higher throughput thermal solutions using heated molds were described (Nakagawa 2005), and pulsed heating
(Tormen 2005).
NEXT
For more source information on each item go to References, or to the abstract book for the conference.
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