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  • The question that arises in our mind is what is mems or micro elctro-mechanical system?It is a technique of combining electrical and mechanical components together on a chip. It produce a system of miniature dimensions i.e the system having thickness less than the thickness of human hair. The components are integrated on a single chip using micro fabrication technology which allows the microsystem to both sense & control the environment.
  • Wet Etching: where the material is dissolved when immersed in a chemical solution.Dry Etching: where the material is sputtered or dissolved using reactive ions or an etching agent.
  • The MEMS devices, in marine sensing maybe attached to:  Ships Floating devices (buoys) in the sea Fixed sea structures (like oil rigs) Sea bed using links AUVs(Autonomous Underwater Vehicle)

Mems seminar Presentation Transcript

  • 1. Outline  MEMS Introduction  Sensor and its type  Fabrication  MEMS Manufacturing Technology  Applications  Conclusion 31-Mar-14 1
  • 2. MICRO ELECTRO MECHANICAL SYSTEMS (MEMS) Raghvendra Kumar Pandey 10/ME/123 National Institute Of Technology Durgapur 31-Mar-14 2
  • 3. What is MEMS?  MEMS or Micro-Electro Mechanical System is a technique of combining Electrical and Mechanical components together on a chip, to produce a system of miniature dimensions.  MEMS is the integration of a number of micro- components on a single chip which allows the microsystem to both sense and control the environment.  The components are integrated on a single chip using micro fabrication technologies. 31-Mar-14 3
  • 4. 31-Mar-14 4  MEMS is a precision device technology that integrates mechanical element, sensors, actuators and electronics on a common silicon substrate through micro fabrication technology.  In MEMS devices, a three-dimensional spatial structure is formed on the substrate and mechanical blocks are formed within that structure.  These devices can replace bulky sensors and actuators with micron-scale equivalents.
  • 5. How MEMS works…?? 31-Mar-14 5 Micro sensors detect in the change of environment by measuring mechanical, thermal, magnetic, pressure, or chemical information. Micro electronics or control unit processes the information sent by actuators and sensors Micro electronics sends output signals to actuators to create change in environment For example of a MEMS device:- An accelerometer used for automobile air bags.  In addition to micro machined components, MEMS packages typically includes signal conditioning Circuits, self testing and calibration, with all required input and output terminals.
  • 6. Are you still confused between Integrated Circuits and MEMS..? 1. MEMS are 3-D complex structure 2. Doesn’t have any basic building block. 3. May have moving parts 4. May have interface with external media 5. Functions include mechanical, chemical, optical and biological and lots of more 6. Packaging is very complex 1. IC’s are 2-D structure 2. Transistors are basic building blocks 3. No moving parts 4. Totally isolated from external media 5. Only electrical functions performed 6. Packaging is already well developed 31-Mar-14 6
  • 7. Reasons why MEMS instead of SENSORS..  Smaller in size  Have lower power consumption  More sensitive to input variations  Cheaper due to mass production using batch fabrication Techniques.  It allows integrated systems, viz. sensors, actuators circuits etc. in a single package and hence offers higher reliability, performance and easy of use. 31-Mar-14 7
  • 8. Components of MEMS 31-Mar-14 8  While the functional elements of MEMS are miniaturized structures sensors, actuators, and microelectronics, the most notable elements (perhaps most interesting) are the micro sensors and micro actuators.  Micro sensors and micro actuators are collectively categorized as Transducers which are the device that convert one form of energy to another form i.e mechanical energy to electrical signals.
  • 9. What is a Sensor?  A device used to measure a physical quantity(such as temperature) and convert it into an electronic signal of some kind(e.g. a voltage), without modifying the environment.  What can be sensed? Almost Everything!!! Commonly sensed parameters are:  Pressure  Temperature  Flow rate  Radiation  Chemicals  Pathogens N S EW 2 Axis Magnetic Sensor 2 Axis Accelerometer Light Intensity Sensor Humidity Sensor Pressure Sensor Temperature Sensor 31-Mar-14 9
  • 10. Type of Sensors Mechanical Sensors • Strain Gauges • Accelerometers • Pressure Sensors • Microphones • Gyroscopes(Rotation Rate) Optical Sensors • Direct Sensors (Light  Electronic Signal) • Indirect Sensors (Light  Intermediate Energy  Electronic Signal) • Biological Light Sensors Thermal Sensors • Thermo mechanical (Dimension) • Thermo Resistive (Resistance) • Acoustic (Sound) • Biological Chemical & Biological Sensors • Electronic Nose • Electronic Tongue 31-Mar-14 10
  • 11. Fabrication of MEMS Materials used for developing micro sensors are:  Silicon  Polymers  Metals  Ceramics Basic Process Deposition Patterning Etching 31-Mar-14 11
  • 12. Basic Process of Fabrication  Deposition  Deposition that happen because of a chemical reaction or physical reaction. 1] Chemical vapor deposition 2] Physical deposition (sputtering)  Patterning or lithography  The pattern is transfer to a photosensitive material by selective exposure to a radiation source such as light. If the resist is placed in a developer solution after selective exposure to a light source, it will etch away.  Etching  Etching is the process of using strong acid to cut into the unprotected parts of a metal surface to create a design in.  There are two classes of etching processes:  Wet Etching  Dry Etching. 31-Mar-14 12
  • 13. 31-Mar-14 13 LithographyFabrication process
  • 14. MEMS Manufacturing Technology Bulk Micromachining Surface Micromachining High Aspect Ratio (HAR) Silicon Micromachining 31-Mar-14 14
  • 15. MEMS Manufacturing Technology  This technique involves the selective removal of the substrate material in order to realize miniaturized mechanical components.  A widely used bulk micromachining technique in MEMS is chemical wet etching, which involves the immersion of a substrate into a solution of reactive chemical that will etch exposed regions of the substrate at very high rates. Bulk Micromachining Etched grooves using (a) Anisotropic etchants, (b) Isotropic etchants, (c) Reactive Ion Etching (RIE) 31-Mar-14 15
  • 16. MEMS Manufacturing Technology  In surface micromachining, the MEMS sensors are formed on top of the wafer using deposited thin film materials. Surface Micromachining 1. Grow silicon dioxide 2. Apply photo resist 3. Develop and expose 4. Etch silicon dioxide 5. Remove photoresist 6. Deposit polysilicon 7. Remove silicon dioxide 31-Mar-14 16
  • 17. MEMS Manufacturing Technology  HAR combines aspects of both surface and bulk micromachining to allow for silicon structures with extremely high aspect ratios through thick layers of silicon (hundreds of nanometers, up to hundreds of micrometers).  HAR MEMS technology enables a high degree of immunity to high-frequency, high-amplitude parasitic vibrations. High Aspect Ratio (HAR) Silicon Micromachining 31-Mar-14 17
  • 18. Applications in Medical Science  Bio cavity Laser : This device distinguishes cancerous from non cancerous cells thus aiding the surgeons in operations.  Inkjet print heads.  Pressure and chemical flow analysis.  Smart Pill :  Implanted in the body  Automatic drug delivery (on demand)  Sight for the blind : MEMS based array that may be inserted in the retina of a blind person to provide partial sight 31-Mar-14 18
  • 19. Applications in Marine Science Sensing in marine environment maybe done for various reasons: Oil exploration and related applications Global weather predictions Monitor water quality for any contamination Measure parameters detrimental to the “health” of structures in the sea ( like oil rigs and ships ) Study of aquatic plants and animals In military operations 31-Mar-14 19
  • 20. Applications in Marine Military Operations  An array of MEMS sensors spread on the ocean floor could detect the presence of enemy submarines.  MEMS sensors (pressure sensors, accelerometers etc.) are being used in anti-torpedo weapons on submarines and ships.  MEMS sensors in torpedoes are responsible for Detonating the torpedo at the right time Hitting the target in a crowded environment Prevent any premature explosion 31-Mar-14 20
  • 21. CONCLUSION  MEMS promises to be an effective technique of producing sensors of high quality, at lower costs.  As with all emerging technologies, the MEMS industry had been predicted to revolutionize technology and our lives.  MEMS can create a proactive computing world, connected computing nodes automatically, acquire and act on real-time data about a physical environment, helping to improve lives, promoting a better understanding of the world and enabling people to become more productive. 31-Mar-14 21
  • 22. 31-Mar-14 22