NC State University

ERL MEMS Interconnect Design

MEMS component

The ability to create microelectro-mechanical systems, dubbed MEMS, on the same surface and with the same fabrication process as integrated circuits will give future chip makers an explosion of options in their designs. MEMS, by itself, enables designers to create motors, sensors, and actuators on the micron scale. Nevertheless, the real benefits of this technology will be realized as a result of manufacturability. Because MEMS designs can be implemented in the same thin-film and doped silicon that make up IC's, designers can easily integrate this technology into VLSI and ULSI, creating designs for a broader range of applications without a major increase in technology cost.

We are investigating MEMS design for applications in high bandwidth optical routing, optical scanners and laser radar, and high speed digital switching and RF electrical signal routing.

Current Students working on these projects

  • Bruce Duewer. PhD student working on Applications of MEMS to High Speed Interconnect.
  • Umut Eksi. PhD student working on Novel Interconnect Circuits.
  • Som Palchuadhury. MS student working on Optical Interconnect.
  • John Tucker. MS student working on Applications of MEMS to High Speed Interconnect.
  • John Wilson. PhD student working on Applications of MEMS to RF and Microwaves.
  • David Winick. PhD student working on Applications of MEMS to Laser Radar.

Overview of Research Chips

Here are our first two chip designs:

HC1

HoloChip1 (or HC1, for short) is the name we gave to the first of this series of MEMS chips exploring high-speed signal routing and display applications.
The chip includes MEMS structures for both electrical and optical interconnect.
HC2

HoloChip2 (or HC2, for short) is the name we gave to the second of this series of MEMS chips exploring high-speed signal routing and display applications.
The chip includes MEMS structures for both electrical and optical interconnect.
HC1HC2

These chips include elements for study in the following domains:

Of the many micro-actuation methods available, we chose to study the following:

Fabrication Process

Our first two chips were fabricated via the MUMPs process, which consists of the following layers:

LayerSizeDescriptionNotes
Metal500nmCr-PtEvaporation deposited, liftoff patterned
Poly21.5um2nd structural layerDoped just as Poly1 through annealing *
Oxide2500nmPSGThin & Thick etched **
Poly12.0um1st structural layerAnnealed/Phosphorus doped above & below
Oxide12.0umPSGLPCVD/RIE Dimpled 750nm deep/RIE
Poly0500nm0-layer polysiliconLPCVD/masked/Reactive Ion Etched
SiN500nmIsolation layerLPCVD -unetchable-
Wafer100mmIsolated substrateHeavily doped n-type(100) w/ Phosphorus

* creates fine-grain size and low internal stress; poly is undoped initially.
** thick etch goes through oxides until it reaches nitride or substrate.

Other known facts about the process:

Smallest distinguishable feature size2um
Young's Modulus for polysilicon layers155.0E12 Pascals ***
Polysilicon resistivity1e-3 Ohm*cm

*** assuming structures are sufficiently large that surface tensions do not play a significant factor.

3-D Visualization Demo!

Layout of MEMS Device For those with browsers configured to view VRML files (Virtual Reality Modeling Language):

Related Information

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