Tag Archives: MEMS

MEMS Mirrors for LIDAR

Clever integration of new microelectronic/nanoelectronic technologies will continue to provide increased functionalities for modern products. Light Imaging, Detection, And Ranging (LIDAR) technology uses lasers to see though fog and darkness, and smaller less expensive LIDAR systems are needed for autonomous driving applications now being developed by dozens of major companies around the world. A significant step in the right direction has been taken by the US government’s Lawrence Livermore National Laboratory (LLNL) after working with AMFitzgerald on a MEMS mirror Light-field Directing Array (LDA) prototype.

In-process photo of the Light-field Directing Array (LDA) MEMS prototype designed by Lawrence Livermore National Laboratory. (Source: AMFitzgerald & Assoc.)

In-process photo of the Light-field Directing Array (LDA) MEMS prototype designed by Lawrence Livermore National Laboratory. (Source: AMFitzgerald & Assoc.)

For the past several years, AMFitzgerald has been developing the fabrication process for a novel MEMS micro-mirror array designed by Dr. Robert Panas’s research group at LLNL, as shown in this video. The technology has been developed specifically to serve LIDAR, laser communications, and other demanding applications where existing MEMS mirror array technologies are insufficient. The novel design offers exceptional speed and tilt range, with three axes (tip-tilt-piston), feedback control, and 99% fill factor. The technology is available for license from the LLNL Industrial Partnerships Office.

At the upcoming MEMS & Sensors Technical Congress, on May 11, Dr. Carolyn D. White will present a case study on how she developed this complex prototype and leveraged AMFitzgerald’s ecosystem of partners to integrate specialty processes. Dr. Alissa Fitzgerald—founder and principle of AMFitzgerald leading the development of innovative MEMS and sensor solutions for specialty applications—will be giving a keynote address on “Next Generation MEMS Manufacturing” at 9:10am May 17 during The ConFab. Dr. Fitzgerald has unparalleled expertise in how to best design MEMS for different fab lines, and is a speaker not to be missed.


Broadening Scope of SEMICON

Once upon a time, SEMICONs were essentially just for semiconductor manufacturing business and technology, and predominantly CMOS ICs. Back when we followed public roadmaps for technology to maintain the cadence of new manufacturing nodes in support of Moore’s Law, it was sufficient to focus on faster transistors connected with tighter wires. Now in an era that is at least partially “More-than-Moore”—as we like to refer to heterogeneous integration of non-CMOS technologies into commercial ICs—SEMICON West 2016 will focus on technologies beyond silicon CMOS such as MEMS and flexible organic semiconductors.

Alissa Fitzgerald, founder and managing member of AM Fitzgerald & Associates, will present on some of these themes Wednesday afternoon during the “What’s Next in MEMS and Sensors: Innovations to Drive the Next Generation of Growth” session (Track 2) of SEMICON’s Advanced Manufacturing Forum. Much of that growth is expected to be in sensors, microprocessors, ultra-low-power supplies, and communications chips to support the Internet of Things (IoT) connected by high-speed 5G data networks.

Flexible/Hybrid Electronics Forum at SEMICON West this year includes two full days of excellent presentations on new technologies that include thinned device processing, device/sensor integrated printing and packaging, and reliability testing and modeling. The following is the full list of forums this year:

  • Advanced Manufacturing,
  • Advanced Packaging,
  • Extended Supply-Chain,
  • Flexible/Hybrid Electronics,
  • Silicon Innovation,
  • Sustainable Manufacturing,
  • Test, and
  • World of IoT.

Partner programs include focused forums discussing trends in technology, markets, and the business of commercial IC fabrication. The industry’s default center of “More Moore” R&D is now imec in Belgium, and invited attendees of the imec technology forum (ITF) in San Francisco happening on July 11th the day before the start of SEMICON West will learn about the latest results in CMOS device shrinking from finFETs to nanowires. The next evening, French R&D and pilot manufacturing center CEA-Leti will lead a workshop detailing how to partner with the organization to bring sensor-based “More-than-Moore” technologies to market. Thursday morning will feature the Entegris Yield Breakfast Forum discussing the need for new materials handling solutions due to “Yield Enhancement Challenges in Today’s Memory IC Production.”

As the official event website summarizes:  We’ve deepened our reach across the full electronics manufacturing supply chain to connect you with more key players — including major industry leaders like Cisco, Samsung, Intel, Audi, Micron, and more. New players, demand generators, systems integrators, and emerging industry segments — all connecting in one place. Keynote presentations will be provided by Cisco Systems, Kateeva, and Oracle.


Litho becomes Patterning

Once upon a time, lithographic (litho) processes were all that IC fabs needed to transfer the design-intent into silicon chips. Over the last 10-15 years, however, IC device structural features have continued to shrink below half the wavelength of the laser light used in litho tools, such that additional process steps are needed to form the desired features. Self-Aligned Double Patterning (SADP) schemes use precise coatings deposited as “spacers” on the sidewalls of mandrels made from developed photoresist or a sacrificial material at a given pitch, such that after selective mandrel etching the spacers pitch-split. SADP has been used in HVM IC fabs for many years now. Self-Aligned Quadruple Pattering (SAQP) has reportedly been deployed in a memory IC fab, too.

An excellent overview of the patterning complexities of SAQP was provided by Sophie Thibaut of TEL in a presentation at SPIE-AL on “SAQP integration using spacer on spacer pitch splitting at the resist level for sub-32nm pitch applications.” Use of a spacer-on-spacer process flow—enabled by clever combinations of SiO2 and TiO2 spacers deposited by Atomic Layer Deposition (ALD)—requires the following unit-process steps:
1 193i litho,
2 ALD spacers,
2 wet etches, and
4 plasma etches.

Since non-litho processes dominate the transfer of design-intent to silicon, from first principles we should consider such integrated flows as “patterning.” Etch selectivity to remove one material while leaving another, and deposition dependent on underlying materials determine much of the pattern fidelity. Such process flows are new to IC fabs, but have been used for decades in the manufacturing of Micro-Electrical Mechanical Systems (MEMS), though generally on a patterning length scale of microns instead of the nanometers needed for advanced ICs. R&D labs today are even experimenting with Self-Aligned Octuple Patterning (SAOP), and based on the legacy of MEMS processing it certainly could be done.


Leti Shows MEMS on 300mm Wafers

As reported by EETimes from the European MEMS Summit last month, French research institute CEA-Leti has manufactured accelerometer MEMS devices on 300mm-diameter wafers. This technology is currently being transferred to Tronics Microsystems SA (Grenoble, France), which currently only manufactures on 200mm wafers. Since CEA-Leti has long functioned as the R&D group for STMicroelectronics (ST), and previously led the way for ST to produce MEMS chips on 200mm-diameter wafers, we may expect that 300mm-wafer MEMS processing is now on ST’s internal roadmap.
Moving production to larger wafers makes sense when either the chip-size or the manufacturing volume increase in size. Much of the growth in demand for MEMS is for so-called “combo” sensors that combine multiple sensor technologies, such as CEA-Leti’s piezo-resistive silicon nanowire technology which allows the accelerometer, gyroscope, magnetometer, and pressure sensor capability to be integrated on the same chip.
The compatibility of Leti’s 200mm-developed technologies with 300mm wafer fabrication, “shows a significant opportunity to cut MEMS production costs,” said Leti CEO Marie Semeria in a press release. “This will be especially important with the worldwide expansion of the Internet of Things and continued growing demand for MEMS in mobile devices.” Sensors of all sorts will be needed for all of the different “Things” to be able to capture new useful information, so we may expect that demand for combo MEMS devices will continue to increase.

Silex’ Strategic Acquisition by China

A secretive investment holding company out of Hong Kong named GAE Ltd has acquired 98% of the shares in Silex Microsystems AB (Jarfalla, Sweden). The transaction took place on July 13th of this year when the former major shareholders agreed to sell all of their respective holdings, while Silex founder and CEO Edvard Kalvesten retains 2% of the shares in the company and continues his role as CEO and board member of Silex. No changes are made to the organizational structure or business operations of Silex, while the new owners plan to build a new high-volume manufacturing line near Beijing that clones the equipment and processes in Sweden with first wafers out by mid-2017 (as reported at EETimes).

Silex claims to be the “world’s number one Pure Play MEMS Foundry”, has worked with AMFitzgerald&Assoc. on RocketMEMS shuttle wafers to reduce MEMS development time by 6-12 months, and has developed multiple Through-Silicon Via (TSV) technologies to allow for efficient 3D integration of MEMS and CMOS.

Almost lost as a footnote in the news is that Silex holds IP on lead-zirconium-titanate (PZT) thin-film technology that allows for efficient piezo-electric energy-harvesting chips. MicroGen Systems is currently in the market with aluminum-nitride (AlN) piezo-cantilever micro-power generator system to power IoT nodes by scavenging either single-frequency or multi-frequency vibrations, working with X-Fab in Germany as foundry partner. If PZT-based piezo-cantilever energy harvesters can compete with AlN-based devices then the former could constitute much of the product volume in the new Silex Beijing fab. In 2014, Yole Developpement forecast “the integration of IoT-dedicated electronic components to result in a market volume of 2B units for these devices by 2021;” if 30% will use energy harvesting then this represents 600M units globally.


Oscar for DMD Inventor Hornbeck

Texas Instrument Oscars 1Kudos to Dr. Larry J. Hornbeck, the extended team at Texas Instruments (TI) that has worked on Digital Micromirror Device (DMD) technology, and to the TI executives who continued to fund the R&D through years of initial investment losses. Hornbeck has been awarded an Academy Award® of Merit (Oscar® statuette) for his contribution to revolutionizing how motion pictures are created, distributed, and viewed using DMD technology (branded as the DLP® chip for DLP Cinema® display technology from TI).

The technology now powers more than eight out of 10 digital movie theatre screens globally. Produced with different resolutions and packages, DLP chips also see use in personal electronics, industrial, and automotive markets. The present good-times with DMD are enjoyed only because TI was willing to make a major long-term bet on this novel way to modulate pixel-arrays, which required building the most complex Micro-Electro-Mechanical System (MEMS) the world had ever seen.

Development of the DLP chip began in TI’s Central Research Laboratories in 1977 when Hornbeck first created an array of “deformable mirrors” controlled with analog circuits. In 1987 he invented the DMD, and TI invested in developing multiple money-losing generations of the technology over the next 12 years. Finally, in 1999 the first full-length motion picture was shown with DLP Cinema technology, and since then TI claims that the technology has been installed in more than 118,000 theaters around the globe. We understand that TI now makes a nice profit from each chip.

“It’s wonderful to be recognized by the Academy. Following the initial inventions that defined the core technology, I was fortunate to work with a team of brilliant Texas Instruments engineers to turn the first DMD into a disruptive innovation,” said Hornbeck, who has 34 U.S. patents for his groundbreaking work in DMD technology. “Clearly, the early and continuing development of innovative digital cinema technologies by the DLP Cinema team created a definitive advancement in the motion picture industry beyond anyone’s wildest dreams.”


Micro-Buckled 3D Silicon Scaffolds

3Dsilicon_CompressiveBucklingA new silicon microstructural solution announced this month is so powerful in creating 3D patterns from 2D surface machining that I just have to share. The figure shows 3D silicon microstructures formed by compressive buckling. The method can be used to create objects with features as small as 100 nm that could be useful for developing new technologies for medicine, energy storage and even brain-like electronic networks. Note that the silicon is surface-machined using standard MEMS processes, and that all manner of silicon circuitry and thin-film sensors could be integrated into this silicon.

Colleagues from the University of Illinois at Urbana-Champaign, Northwestern University, Zhejiang University, East China University of Science and Technology, and Hanyang University created the new 2D-to-3D fabrication technique. Their trick is that after all other surface machining they chemically modify the square anchors in the surface pattern such that they are sticky. After the 2D pattern is released it is transferred onto a sheet of stretched silicone rubber. Allowing the rubber to relax back to its natural shape draws the squares toward each other, while the rest of the silicon buckles upwards. Using this type of controlled buckling, the team managed to produce a variety of elaborate 3D shapes.

The researchers even produced structures with multiple levels of elevation by designing shapes in which the relief of stress in the initial 2D shape would create further buckling, raising another part of the shape further. John Rogers of the University of Illinois at Urbana-Champaign, who is part of the micro-buckling team looks forward to an electronic cell or tissue scaffold, “A lot of the people that we talk to are enthusiastic about what you can do when you go from a passive scaffold to something that embeds full electronic functionality.”

The research is published in Science.