mechanical systems (MEMS) have
been around for years, and have found their way into high-volume applications
such as automobile air bag controllers, GPS systems, and inkjet print heads.
But MEMS devices such as accelerometers, gyroscopes, RF switches and pressure
sensors are not as widely used as they could be. There are three limitations to
the widespread use of MEMS:
- MEMS design typically requires PhD-level
experts in areas such as mechanical, optical, fluidic, and package design.
- MEMS historically requires
specialized process development for each design, and is mostly confined to
IDMs who have their own fabs.
- Even though most MEMS devices
reside within electronic systems, the MEMS design flow has been totally
separate from the EDA environment.
result, bringing a MEMS product to market today can cost $40 million, and take
4-10 years of development time. Multi-disciplinary teams of experts are required.
The biggest growth area for MEMS is in high-volume consumer applications, and
long, expensive development cycles won't cut it there.
needed is a way to bring MEMS out of the realm of experts working for IDMs, and
into the IC design mainstream. Mike Jamiolkowski, CEO of MEMS tool provider Coventor, calls this process the
"democratization of MEMS." This will result in a shift from traditional MEMS
companies to semiconductor foundries and fabless design houses, and will make
MEMS ubiquitous in everyday life, he says.
democratization of MEMS calls for a more standardized design flow. What's
needed is a "Mead
Conway equivalent" for MEMS, as Randy Fish, product marketing director at
Cadence, puts it. An important part of that flow is the ability to simulate a
MEMS device along with the electronic circuitry in the overall system. "MEMS
typically don't stand alone," Mike said. "MEMS and electronics interact
strongly, and the designs need to be simulated together."
important is an ability to import a MEMS device into a schematic, and
ultimately into a physical layout, of the entire system. Unfortunately, MEMS
designers use 3D CAD/CAE tools while electronics designers work with EDA tools
such as the Cadence Virtuoso platform. The handoff from MEMS designers to IC or
package designers is mostly manual, requiring the expert handcrafting of MEMS
models for the EDA environment.
product takes a different approach. After assembling a 3D design, users can
generate a schematic symbol for the Cadence Virtuoso environment, a netlist for
the Cadence Spectre or Ultrasim simulators, and a PCell for Cadence Virtuoso
layout. The MEMS device can be inserted into the schematic and simulated along
with the electronic circuitry. The MEMS designer can view the simulation
results in the Coventor 3D environment.
result, Mike said, "the handoff to the IC engineer is very simple, very clean."
He said Coventor is selling MEMS+ to IC design teams as well as MEMS designers,
opening up a new marketplace for MEMS design. Some expertise is still required
to build the 3D MEMS device, but the barrier to entry is a lot lower than with
traditional MEMS CAD systems, Mike said. An article
on the Design Automation Conference (DAC) web
site, co-authored by Coventor and Cadence, provides further perspectives
about the connection of MEMS development to the IC design environment.
challenge is developing standard foundry processes for MEMS. There is some
progress. According to Mike, many IDMs have figured out how to develop MEMS
processes that can handle derivative designs, as opposed to the traditional
"one design, one process" approach. There are also a number of specialized MEMS
foundries are beginning to show interest. In 2008 TSMC announced it would upgrade a portion
of its 0.35 micron logic process capacity to MEMS. In October 2009, Cypress spinoff SVTC and
TSMC announced a joint
development effort aimed at MEMS commercialization. What is ultimately
needed is a foundry infrastructure including process development kits (PDKs),
IP, and reference flows.
right tooling and with foundry support, we may be standing at the threshold of
a tiny revolution.