MEMS. NANO51 Foothill College

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1 MEMS NANO51 Foothill College

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3 Overview What are MEMS/NEMS? History of MEMS Applications and examples Making MEMS Future of MEMS

4 What are MEMS/NEMS? Acronym for: Micro Electro Mechanical Systems Nano Electro Mechanical Systems But what does this mean????

5 The Role of MEMS While the functional elements of MEMS are miniaturized structures, sensors, actuators, and microelectronics, the most notable (and perhaps most interesting) elements are the microsensors and microactuators. Microsensors and microactuators are appropriately categorized as transducers, which are defined as devices that convert energy from one form to another. In the case of microsensors, the device typically converts a measured mechanical signal into an electrical signal. Micro-Electro- Mechanical Systems, or MEMS, is a technology that in its most general form can be defined as miniaturized mechanical and electro-mechanical elements (i.e., devices and structures) that are made using the techniques of microfabrication. The critical physical dimensions of MEMS devices can vary from well below one micron on the lower end of the dimensional spectrum, all the way to several millimeters. Michael Huff, Michael Huff is at the MEMS Exchange, Corporation for National Research Initiatives, 1895 Preston White Drive, Suite 100, Reston, Virginia , USA

6 MEMS Smart Matter MEMS technology combines mechanical devices and electronics on a micro or nano scale Examples are sensors, valves, gears, mirrors, and actuators embedded in semiconductor chips. MEMS are sometimes referred to as smart matter.

7 MEMS Ratchet Imagine a machine so small that it is imperceptible to the human eye. Imagine working machines no bigger than a grain of pollen. Imagine thousands of these machines batch fabricated on a single piece of silicon, for just a few pennies each. Imagine a world where gravity and inertia are no longer important, but atomic forces and surface science dominate. Imagine a silicon chip with thousands of microscopic mirrors working in unison, enabling the all optical network and removing the bottlenecks from the global telecommunications infrastructure. You are now entering the micro-domain, a world occupied by an explosive technology known as MEMS. A world of challenge and opportunity, where traditional engineering concepts are turned upside down, and the realm of the "possible" is totally redefined.

8 MEMS/NEMS Nanosystems and Micro-Electro- Mechanical Systems (MEMS) are the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through the utilization of microfabrication technology.

9 Foundational Technology Paul Saffo of the Institute for the Future in Palo Alto, California, believes MEMS or what he calls analog computing will be "the foundational technology of the next decade."

10 Other MEMS Terms Microengineering: the technologies and practice of making three dimensional structures and devices with dimensions in the order of micrometers. Micromachining: techniques used to produce the structures and moving parts of micro engineered devices Microsystems: The integration of microelectronic circuitry into micromachined structures, to produce completely systems Source: Danny Banks

11 Micromachining/MEMS Micro-sensors Applications Light detectors, pressure sensors, strain gages, temperature sensors Micro-actuators Valves, gears, motors, resonators, cantilevers Structures Cavities, microneedles, fluidic channels, lenses, membranes Lab-on-a-chip / micro-fluidics / diagnostics in medicine / BioMEMS

12 What are Transducers? A transducer is a medium for transforming energy between 2 or more domains A sensor measures something in its surrounding environment and provides a response related to the measured parameter A mechanical actuator converts electrical signals into a mechanical action Source: Micromachined Transducers Sourcebook by Gregory Kovacs

13 MEMS Applications Automotive Telecommunications Sensors Actuators BioMEMS

14 MEMS: Micromachines As the name implies, micromachines are very tiny mechanisms. In fact, they are so small that the unaided eye cannot perceive them. Many different types of professionals, such as biologists, chemists, physicists, and engineers, are involved in the research and development of these complex devices. Micromachines can be a wide variety of different mechanisms, such as fluid channels, gears, engines, tweezers, and mirrors - all smaller than the width of a human hair. So, what are these micro-devices used for? Well, many of them are creeping into our everyday lives, in places where you may not expect them.

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16 MEMS Sensors and Actuators (NTS: get pictures) Automotive Force, Pressure, Sound, and Vibration Optical sensors (visible and IR / UV) Fluid flow (in micro environments) Industrial chemical and gas sensors Interfacing MEMS Sensors and Actuators with Microcontrollers

17 Accelerometers NTS: get pictures and discuss how it works MEMS accelerometers are used for airbag deployment in cars

18 MEMS Accleromters A device that detects acceleration and tilt. Built using MEMS technology, accelerometers detect impact and deploy automobile airbags as well as retract the hard disk's read/write heads when a laptop is dropped. Digital cameras employ them in their image stabilization circuits. They are used in washing machines to detect excessive vibration and in pedometers for more accurate distance measurement. They also enable a handheld display to be switched between portrait and landscape modes when the unit is turned. MEMS accelerometers initially used a microminiaturized cantilever-type spring, which converts force into a displacement that can be measured. Subsequent accelerometers use a heated gas bubble with thermal sensors and function much like the air bubble in a construction level. When the accelerometer is tilted or accelerated the sensors pick up the location of the gas bubble.

19 Microfabrica Accelerometer The device at the bottom left with the C-shaped wings is an accelerometer. Built one metal layer at a time, Microfabrica's EFAB system was the first MEMS foundry process to quickly turn customers' CAD files into micromachines. (Image courtesy of Microfabrica Inc.,

20 More MEMS Pictures Gears Tweezers Springs Mirrors Cavities Comb drives Microneedles/tips

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22 BioMEMS Applications (NTS: get pictures) Lab-on-a-chip Micro fluidics DNA extraction / separation technology Protein separation / purification Electrophoresis, capillary flow measurements Biochips, microarrays, microsensors In vivo diagnostic sensing Smart-sensing in implantable devices

23 Bio-Microelectromechanical Systems BYU BioMEMS research focuses on using microelectromechanical devices to move DNA and other molecules across biological cell boundaries. The effort uses a revolutionary method based on nanoelectromechanical principles to place DNA inside of cells without harming them. The research contributes to our understanding of many diseases, including cancer, and has promise for future therapies for genetic disorders.

24 Computational MEMS Interfacing microcontrollers and MEMS Packaging issues of MEMS and CPU interconnection reliability similar to standard plastic IC packaging processes based on a standard flow for plastic packages applicable for a wide range of plastic packages (e.g. SOIC, QFP, PLCC, SSOP, BGA, CSP) can be applied with multi-chip concepts (sensors + ASIC) package cost for medium to high volumes

25 System on a Chip

26 Making MEMS

27 When does it make sense to Micromachine? Just because something can be built on a micro or nano scale, doesn t mean that it should There has to be a significant advantage over conventional designs

28 What are the Possible Advantages? Low cost from high volume fabrication (example: air bag sensors) Mechanical reliability Precise sensing techniques Access to areas/information where larger components can not reach Smaller components may provide convenience

29 Possible Disadvantages Lower tech solutions could be cheaper High development costs (motorization of R&D, packaging, and testing costs) Mechanical properties are different at the micro and macro scale Power supply may dwarf any advantages to smaller size Signal quality may be compromised at the microscale Thermal instability Difficulty in packaging

30 MEMS Materials / Environments Silicon technology Carbon based polymers Future working environments CNT integration Colloids / fluids Biological systems High pressure / reactive gas systems

31 MEMS Processing Techniques Standard silicon technology (IC fab techniques) Bulk micromachining Surface micromachining Polymers Electro Discharge Machining Molding

32 Micromachining Because silicon dominates the IC fabrication industry, it also dominates many of the fabrication techniques for nanotech forerunners such as MEMS and NEMS While the electronics are fabricated using IC process sequences, the micromechanical components are usually fabricated using compatible "micromachining" processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical devices

33 Bulk versus Surface Micromachining Bulk micromachining develops structures by selectively etching a silicon wafer Surface micromachining develops structures by selectively adding thin films and layers on the surface of a silicon or other appropriate substrate

34 MEMS Processing Techniques Deposition processes Lithography and photolithography Etching processes Surface treatments and coatings Packaging and CPU integration Metrology techniques for QA/QC

35 MEMS Application: Nanoindention for storage Discuss process to make, show end result, and what the advantages are and how it would work Etc.

36 Current Trends and Future Directions in MEMS Downward cost pressure Increased / specialized functionality Integration in biological systems Integrating with CPUs / ASICS / RFID Mechanical assembling functionality Rudimentary mechanical functioning beyond simple sensors / actuators

37 MEMS Market Opportunities MEMS market size 2000 to 2005 (innovation) 2005 to 2010 (adoption / growth) 2010 to 2015 (maturation / mainstream) NTS: Get trend data

38 Challenges Facing MEMS Limits to silicon processing Three dimensions of exactness Cost and reliability of manufacturing Integration in biological systems Serviceability, design cycles Integration with CPUs / communications Needs an industry sponsor (like RFID) PACKAGING

39 Self Assembly and Micro/Nano Electronics Micro-sensor Micro-accelerometer Micro-mirror Micro-gear

40 What are MEMS/NEMS? Micro-Electro-Mechanical Systems (MEMS) are the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through microfabrication technology. Micro-sensor Micro-accelerometer Micro-mirror Micro-gear

41 MEMS vs. Integrated Circuits (IC s) One way to look at it: IC s move and sense electrons MEMS move and sense mass MEMS act as transducers (sensors) converting a physical property into an electrical property (force to voltage, etc ). MEMS can also actuate mechanical devices (switches, mirrors, etc )

42 1982 LIGA Process Introduced In the early 1980s Karlsruhe Nuclear Research Center in Germany developed LIGA LIGA is a German acronym for X- ray lithography (X-ray Lithographie), Electroplating (Galvanoformung), and Molding (Abformung) Microfluidic device made using LIGA process It allows for manufacturing of high aspect ratio microstructures High aspect ratio structures are very skinny and tall LIGA structures have precise dimensions and good surface roughness Capacitive Comb drive also made using the LIGA process

43 1986 Invention of the AFM In 1986 IBM developed the atomic force microscope (AFM) The AFM maps the surface of an atomic structure Measures the force acting on the tip of a microscale cantilever It is a very high resolution type of scanning probe microscope with a resolution of fractions of an Angstrom

44 MEMS Applications Pressure Sensors Auto and Bio applications Ink Jet Print Heads Accelerometers (Inertial Sensors Crash Bags, Navigation, Safety, iphones) Micromachines Micro Fluidic Pumps Insulin Pump (drug delivery) Spatial Light Modulators (SLM s) MOEM Micro Optical Electro Mechanical Systems DMD Digital Mirror Device Mass Storage Devices Chem Lab on a Chip Cantilever biosensors

45 MEMS Pressure Sensors Pressure Sensors Use piezoresistive silicon sensors The silicon chip flexes as pressure changes The amount the silicon chip flexes determines the output voltage signal. These sensors help improve engine performance including gas mileage.

46 Pressure Sensors TRW Commercial Gas Engine Sensor Top view of the TRW (1985) pressure sensor, the metal components are on top of the silicon membrane. The silicon membrane is stressed when there is a pressure differential.

47 Intercardial catheter-tip sensors These MEMS transducers are used in intercardial catheter-tip sensors for monitoring blood pressure during cardiac catheterization x 0.4 x 0.9 mm Photo courtesy of Lucas NovaSensor, Fremont, CA.

48 Disposable Blood Pressure Sensors Disposable sensors use MEMS transducers to measure changes in blood pressure. Photo courtesy of Motorola, Sensor Products Div., Phoenix, AZ. These $10 devices connect to a patient's IV line and monitor blood pressure through the IV solution.

49 EmKay Sisonic Microphone This microphone is made from Silicon and is only millimeters large. Photo Courtesy of EmKay

50 Ink Jet Ink jet printers are MEMS based 1979 IBM and HP

51 Ink Jet Ink jet printers are MEMS based 1979 IBM and HP

52 1979 HP Micromachined Inkjet Nozzle Close-up view of a Schematic of an array of inkjet commercial inkjet printer nozzles. head illustrating the nozzles. This printing technique rapidly heats ink, creating tiny bubbles. When the bubbles collapse, the ink squirts through an array of nozzles onto paper and other media. Silicon micromachining technology is used to manufacture the nozzles. The nozzles

53 The Accelerometer Analog Devices 1993 Saab was the first automobile company to include MEMS accelerometers to trigger airbags. These MEMS-based systems sense rapid deceleration and in the event of a collision send a signal to inflate rapidly an airbag.

54 The Accelerometer An accelerometer is a sensor for testing the acceleration along a given axis. The simplest MEMS accelerometer is an inertial mass suspended by springs. Deflection of the mass is converted into an electrical signal.

55 iphone Nintendo Wii IBM Thinkpad

56 MEMSIC's Dual-Axis Thermal Accelerator The square in the middle of the chip is a resistor that heats up a gas bubble. The next larger squares contain thermal couples that sense the location of the heated bubble as the device is tilted or accelerated. (Image courtesy of MEMSIC, Inc.)

57 MEMS as Machines MEMS are often referred to as Micro Machines. Tiny devices that move things. Mirror (popped up) Gear Train. Each gear tooth is 8 microns wide.

58 Micro Machines Surface Micromachining takes off in the 1990 s. Sandia National Laboratories This basically consists of alternating layers of structural materials (polycrystalline silicon) and sacrificial layers (Silicon Dioxide). The sacrificial layer is a scaffold and acts as a temporary support and spacing material. The last step of the process is the release step, where the sacrificial layer is removed freeing the structural layers so they can move.

59 Micromachines In this image, the square at the top is a microfluidics device with internal passageways used for a "lab on a chip." The multi-arm device (center) is a fuel injection nozzle. Bottom left is an accelerometer, and bottom right is an inductor used in RF circuits. (Image courtesy of Microfabrica Inc.,

60 Micromachines Microfluidics Device In this image, the square at the top is a microfluidics device with internal passageways used for a "lab on a chip." The multi-arm device (center) is a fuel injection nozzle. Bottom left is an accelerometer, and bottom right is an inductor used in RF circuits. (Image courtesy of Microfabrica Inc.,

61 Micromachines Microfluidics Device Fuel Injection Nozzle In this image, the square at the top is a microfluidics device with internal passageways used for a "lab on a chip." The multi-arm device (center) is a fuel injection nozzle. Bottom left is an accelerometer, and bottom right is an inductor used in RF circuits. (Image courtesy of Microfabrica Inc.,

62 Micromachines Microfluidics Device Accelerometer Fuel Injection Nozzle In this image, the square at the top is a microfluidics device with internal passageways used for a "lab on a chip." The multi-arm device (center) is a fuel injection nozzle. Bottom left is an accelerometer, and bottom right is an inductor used in RF circuits. (Image courtesy of Microfabrica Inc.,

63 Micromachines Microfluidics Device Accelerometer Fuel Injection Nozzle Inducto r In this image, the square at the top is a microfluidics device with internal passageways used for a "lab on a chip." The multi-arm device (center) is a fuel injection nozzle. Bottom left is an accelerometer, and bottom right is an inductor used in RF circuits. (Image courtesy of Microfabrica Inc.,

64 MEMS-based Optical Switch Micro Optical Electro Mechanical Systems (MOEMS) In 1999 Lucent Technologies developed the first optical network switch These MEMS optical switches utilize micro mirrors to switch or reflect an optical channel or signal from one location to another.

65 Digital Mirror Device (DMD) A DMD chip has on its surface several hundred thousand microscopic mirrors which correspond to the pixels in the image to be displayed. Digital Light Projector (DLP)

66 Digital Mirror Device (DMD) The mirrors can be individually rotated ±10-12, to an on or off state.

67 How Small are these Mirrors? Pin Point Each mirror is about 16µm square! Ant Leg DMD mirrors complete DLP units have over 2 million mirrors all functioning!

68 Mass Storage - IBM It works by making small indentations in a polymer film. Higher density data capability IBM s Millipede 100 Tera Bit per square inch!

69 Mass Storage - IBM A two-dimensional array of V-shaped silicon cantilevers, each 70 µm long. Writes divot into polymer by heating tip to 400 C Reads by looking at surface with 300 C tip (measures resistance change with temp drop) if the tip is in a divot, the tip cools more than if it is not therefore, there is a change in resistivity which is measured by the electronics. Erases by making an offset pit, which causes the nearby pit to pop up and hence erases it.

70 BioMEMS The overlap between microbiology and microsystem feature sizes makes integration between the two possible Nucleus Ribosome Eukaryotic cells Bacteria Viruses Proteins 100 µm 10 µm 1 µm 0.1 µm 0.01 µm µm (10 nm) (1 nm) Atom Surface Micromachining Features (MEMS) Visible Light Gate of Leading Edge Transistor Molecules

71 Biomedical Applications Scientists are combining sensors and actuators with emerging biotechnology Applications include drug delivery, DNA arrays, and microfluidics

72 Biomedical Applications Micromachine needles used to deliver drugs Procter and Gamble Plastic Needle Array

73 MEMS Cantilevers Cantilevers are used as Sensors Cantilevers are used as Switches Many MEMS Sensors use the principles of Cantilevers as well as RF Swtiches

74 What is a Cantilever? Cantilevers have a resonant frequency that depends on the length and the mass.

75 MEMS Cantilever sensors The ends of the cantilevers are coated with a layer of probe molecules. When a target molecule is present, it attaches to the probe molecule, thereby increasing the mass. The resonant frequency goes down. You just detected the presence of a molecule!

76 Cantilever Sensors As mass is added to the cantilever shifts the resonance frequency. A gold dot, about 50 nanometers in diameter, fused to the end of a cantilevered oscillator about 4 micrometers long. A one-molecule-thick layer of a sulfur-containing chemical deposited on the gold adds a mass of about 6 attograms (10-18 grams), which is more than enough to measure. Craighead Group/Cornell Univeristy

77 Resonance Shift School of Applied and Engineering Physics and the Nanobiotechnology Center, Cornell University Resonance Shift due to Single Cell 5 x 15um Cantilever with an E. Coli cell bound to antibody layer. Black is the response before cell attachm Red is after cell attachment.

78 Resonance Frequency Shift as a Function of Mass

79 Detection of Single DNA Gold dot = 40nm SiN thickness = 90nm By changing the coating (Nano) one can functionalize the cantilever to detect single strands of DNA. Mass resolution is on the order of under 1 ato gram (10 - gle%20dna.html 18 grams)

80 Future of MEMS Wireless / networked MEMS/BioMEMS Advanced biosensors / actuators Computational MEMS Advanced System on a Chip MEMS systems (networks of MEMS)

81 Summary What are MEMs? What do MEMs do? MEMs applications MEMs fabrication Future MEMs BioMEMS, NMEMS

82 MEMS References MEMS Clearinghouse - About MEMS MEMX All about MEMS cations-optical.html Sandia MEMS Homepage -