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Mems (Detail Presentation)
 

Mems (Detail Presentation)

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Technical Seminar For BE Students "MEMS Technology"

Technical Seminar For BE Students "MEMS Technology"

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    Mems (Detail Presentation) Mems (Detail Presentation) Presentation Transcript

    • Micro-Electro-Mechanical Systems -The Future Technology, but Today’s choice Presented by… Vinayak Hegde Guide: Mrs. Priti M
    • AIM OF MY PRESENTATION
      • To familiarize what the MEMS TECHNOLOGY is all about
      • To explain about Microfabrication Process .
      • Applications of the MEMS in various fields .
    • Outline of My Presentation
        • Introduction
        • Historical Background
              • (MEMS Evolution)
        • Preparation Process of MEMS
              • (Fabrication Process)
        • Applications of MEMS
              • (Fields where MEMS Used )
        • Interrelationship between MEMS and Nano
            • (Future Scope of MEMS)
        • Conclusion
    • Introduction
      • What is MEMS Technology ?
        • MEMS technology is based on a number of tools and methodologies, which are used to form small structures with dimensions in the micrometer scale
        • MEMS fabrication approach that conveys the advantages of miniaturization, multiple components, and microelectronics to the design and construction of integrated Electromechanical systems
    • Introduction Conti…
      • What are MEMS ?
        • • Micro - Small size, microfabricated structures
        • • Electro - Electrical signal /control ( In / Out )
        • • Mechanical - Mechanical functionality (Out/ In )
        • • Systems - Structures, Devices, Systems controls
      • What is the size of MEMS?
        • They range in size from the sub micron level to the millimeter level, and there can be any number, from a few to millions, in a particular system.
    • MEMS Scaling
    • Building Blocks In MEMS
      • How MEMS are prepared?
        • There are three basic building blocks in MEMS technology.
          • Deposition : The ability to deposit thin films of material on a substrate.
          • Lithography : To apply a patterned mask on top of
          • the films by photolithograpic imaging.
          • Etching : To etch the films selectively to the mask.
    • MEMS Deposition Technology
      • MEMS deposition technology can be classified in two groups:
      • Depositions that happen because of a chemical reaction:
          • Chemical Vapor Deposition (CVD)
          • Electrodeposition
          • Epitaxy
          • Thermal oxidation
      • Depositions that happen because of a physical reaction:
          • Physical Vapor Deposition (PVD)
          • Casting
    • MEMS Lithography Technology
      • MEMS lithography technology can be classified in two groups:
      • Pattern Transfer
      • Lithographic Module
          • Dehydration bake and HMDS prime
          • Resist spin/spray and Soft bake
          • Alignment, Exposure
          • Post exposure bake and Hard bake
          • Descum
    • MEMS Etching Technology
      • There are two classes of etching process:
      • Wet etching : The material is dissolved when immersed in a chemical solution.
      • Dry etching : The material is sputtered or dissolved using reactive ions or a vapor phase etchant.
    • Microfabrication Process
    • Photolithography
      • Clean wafer : to remove particles on the surface as well as any traces of organic, ionic, and metallic impurities
      • Dehydration bake : to drive off the absorbed water on the surface
      • Coating
        • Coat wafer with adhesion promoting film
        • Coat with photoresist
      • Soft bake : to drive off excess solvent and to promote adhesion
      • Exposure
      • Post exposure bake : to suppress standing wave-effect
      • Develop, Clean, Dry
      • Hard bake : to harden the PR and improve adhesion to the substrate
    • Photolithography
    • Additive Processes Oxidation Thermal Oxidation of Silicon is done in a furnace in wet or dry conditions
    • Additive Processes Doping Dopants : N type (Phosphorous, Arsenic), P type (Boron)
      • Doping Methods
      • Diffusion
      Dopants are diffused thermally into the substrate in furnace at 950 – 1280 0 C. It is governed by Fick’s Laws of Diffusion. Dopant ions bombarded into targeting substrate by high energy. Ion implantation are able to place any ion at any depth in sample. 2. Ion Implantation
    • Additive Processes Physical Vapor Deposition (PVD) 1. Evaporation Deposition is achieved by evaporation or sublimation of heated metal onto substrate. 2. Sputtering Sputtering is achieved by accelerated inert ion by DC drive in plasma through potential gradient to bombard metallic target. Then the targeting material is sputtered away and deposited onto substrate placed on anode.
    • Additive Processes Physical Vapor Deposition (PVD)
    • Additive Processes Chemical Vapor Deposition (CVD)
      • Materials deposited : Polysilicon, silicon nitride, silicon oxide, silicon carbide etc.
      • How does CVD Work?
        • Gaseous reactants are introduced into chamber at elevated temperatures.
        • Reactant reacts and deposits onto substrate
      • Types of CVD
        • LPCVD (Low Pressure CVD),
        • PECVD (Plasma Enhanced CVD)
      • Salient Features
        • CVD results depend on pressure, gas, and temperature
        • Can be diffusion or reaction limited
        • Varies from film composition, deposition rate and electrical and mechanical properties
    • Subtractive Processes Dry Etching
      • Dry Chemical Etching
      • HF Etching
      • HF is a powerful etchant and hence, highly dangerous.
      • XeF 2 Etching
      • 2XeF2+Si->2Xe+SiF4
        • Isotropic etching (typically 1-3µm/min)
        • Does not attack aluminum, silicon dioxide, and silicon nitride
    • Subtractive Processes Reaction Mechanism Produce reactive species in gas-phase Reactive species diffuse to the solid Adsorption, and diffuse over the surface Reaction Desorption Diffusion Dry Etching Plasma Etching
    • Subtractive Processes Dry Etching Deep Reactive Ion Etching (DRIE) A very high-aspect-ratio silicon etch method DRIE Etched Pillars
    • Subtractive Processes Wet Etching Isotropic Wet Etching Isotropic etchants etch in all directions at nearly the same rate. Commonly use chemical for Silicon is HNA (HF/HNO 3 /Acetic Acid) This results in a finite amount of undercutting
    • Subtractive Processes Wet Etching Anisotropic Wet Etching Anisotropic etchants etch much faster in one direction than in another. Etchants are generally Alkali Hydroxides (KOH, NaOH, CeOH Reaction : Silicon (s) + Water + Hydroxide Ions -> Silicates + Hydrogen
    • Metal Patterning
    • Surface Micromachining
    • MEMS Packaging
    • Example: An insulin pump fabricated by classic MEMS technology 1. Pumping membrane 2. Pumping chamber 3. Inlet 4. Outlet 5. Large mesa 6. Upper glass plate 7. Bottom glass plate 8. patterned thin layer (for improved fluidics)
    • MEMS Applications
      • Micro-engines –Micro Reactors, Vibrating Wheel
      • Inertial Sensors –Virtual Reality Systems
      • Accelerometers –Airbag Accelerometer
      • Pressure Sensors –Air Pressure Sensors
      • Optical MEMS –Pill Camera
      • Fluidic MEMS - Cartridges for Printers
      • Bio MEMS - Blood Pressure Sensors
      • MEMS Memory Units - Flash Memory
    • iPod Touch: Techno Sensitiveness
      • The two key elements of a
      • MEMS are:
        • MEMS sensor, the silicon mechanical element which senses the motion;
        • Interface chip, the IC which converts the motion measured by the sensor into an analog or digital signal.
    • An implantable blood pressure sensor developed by CardioMEMS Bio MEMS Application
    • MEMS Memory [Nanochip]
    • MEMS driven Storage Devices
      • TB to PB device capacities
      • Massively parallel data transfer rates
      • Very fast file access times
      • Improved reliability
      • Smaller size and weight
      • Device costs less than today's devices
      • Excellent fit for applications to enterprise
    • Future of Magnetic Storage
      • HAMR -Heat Assisted Magnetic Recording or TAR -Thermally Assisted Recording
      • SOMA -Self Organized Magnetic Assemblies; a form of directed patterned media.
      • Super high coercivity storage layers (such as FePt) with stable grain sizes averaging < 2nm.
      • Super servos for (coarse/fine) tracking and flying height control.
    • Advantages and Disadvantages
      • Minimize energy and materials use in manufacturing
      • Cost/performance advantages
      • Improved reproducibility
      • Improved accuracy and reliability
      • Increased selectivity and sensitivity
      • Farm establishment requires huge investments
      • Micro-components are Costly compare to macro-components
      • Design includes very much complex procedures
      • Prior knowledge is needed to integrate MEMS devices
    • Conclusion
      • The medical, wireless technology, biotechnology, computer, automotive and aerospace industries are only a few that will benefit greatly from MEMS.
      • This enabling technology promises to create entirely new categories of products
      • MEMS will be the indispensable factor for advancing technology in the 21 st century
    • References for MEMS
      • IEEE Explore http://ieeexplore.ieee.org/Xplore/DynWel.jsp
      • PDF Files http://www.scribd.com/mems/
      • Introduction to Microengineering http://www.dbanks.demon.co.uk/ueng/
      • MEMS Clearinghouse
      • http://www.memsnet.org/
      • MEMS Exchange
      • http://www.mems-exchange.org/
    • Thank You