Kevin Huang Ph.D. Defense (Mon Dec. 15, 2pm, CIS-X 101)

Kevin Huang kevhuang at
Fri Dec 12 09:50:40 PST 2008

Come for some food if still around next Monday!


Title: Expandable Monolithic Silicon Network For Cost-Effective Large Area

University Oral Examination
Kevin Huang
Department of Electrical Engineering
Stanford University
Advisor: Peter Peumans

Date: Monday, December 15, 2008
Time: 2pm (Refreshments served at 1:45pm)
Location: CIS-X 101 (Auditorium)


CMOS technology has progressed substantially over the past decades in terms
of cost per function and energy required per unit of computation due to
advances in microelectronic manufacturing.  Unfortunately, these advances
have not been shared by the field of large area electronics because a
different set of constraints exists in this field, for example, cost per
unit area is an important factor when evaluating the applicability of
technologies.  Therefore, entirely different technologies such as inkjet
printing or other pattern transfer methods are used. One method, fluidic
self-assembly, uses small chiplets of monolithic silicon electronics that
self-assemble at specific sites in a large-area system to realize large-area
electronics. This approach does benefit from advances in CMOS technology and
allows one to build large-area and high-performance electronic systems, but
it has proven challenging to ensure high yields and throughput.

Our approach to construct large-area electronic systems from monolithic
silicon substrates expands a functional silicon die by several orders of
magnitude in area by structuring the silicon die as a two-dimensional
network of silicon islands and springs.  Each island houses electronics and
connects mechanically and electrically via springs to neighboring islands in
a 2D network topology. Electrical interconnects on top of the spiral springs
provide electrical connectivity between the islands. Since all the strain
induced by the expansion process is contained in the spiral springs, the
active device area remains strain free.  Silicon networks with built-in 2D
expandability can also conform to curved surfaces.  The fabrication
processrequired to realize such networks can be performed on a wafer
that has been
fully processed in a foundry as a post-CMOS process.

Expandable silicon is a platform technology that enables the use of
microelectronic manufacturing, with its exponential reduction in cost per
electronic function and exponential increase in performance, in large-area
systems. This preserves the benefits of foundry processing while reducing
cost per unit area to levels compatible with many application domains.  This
technology can be used for the cost-effective manufacturing of
microconcentrator solar cells, RFID tags, sensor networks, curved imagers,
retinal prostheses, and displays. In my talk, I will discuss the design
constraints of expandable silicon, the processes that were developed and
illustrate the use of expandable silicon.
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