The highly complex systems of microscopic elements in MEMS devices can be achieved at reasonable cost due to the batch nature of the lithographic manufacturing process.
Photolithography is inherently a planar process, however. Thus, while three-dimensional structures are often desirable, it is a challenge to microfabricate in three dimensions without losing the manufacturing advantages of lithography.
Pop-up Mechanisms for Efficient 3-D Assembly
The pop-up mechanisms of children's storybooks achieve assembly of
complex 3-D structures out of planar elements initially parallel to
one another with a quick simple motion, the turn of a page.
We have adapted these mechanisms to the microscale to enable
rapid assembly of lithographically fabricated planar structures
into complex 3-D structures.
Carbon Sacrificial Layer for Polysilicon Molding
Thin-film materials can be molded into intricate structures by
depostion onto 3-D substrates. Carbon makes an excellent
sacrificial layer for this molding process, known as
hexsil.
We have formed conformal films of carbonized parylene, resulting
in sub-micron molding precision and a release process that is dry,
rapid and extremely selective, allowing large structures to be
released without damage.
Molding and Bonding of Parylene Structural Films
Using parylene as a structural film, conformally molded polymer
structures can be obtained. There is no need for a
sacrificial layer in our process. Thermal-compression
can be applied to bond multiple layers of molded parylene.
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MEMS primer | 3-D Microfabrication | About me
For more information, please contact me at eehui@ucsd.edu +1.858.822.3843