PPTs

• Microelectronics is a field of electronics engineering that involves the design and fabrication of electronic components on a minuscule scale
• These devices are typically fabricated using microelectromechanical systems (MEMS) or microelectronic mechanical systems (MEMS), which are small structures that can be integrated into electronic circuits
• Transistor


  A fundamental building block of microelectronics
• Benefits of Microelectronics


  • Miniaturization
  • Power efficiency
  • Advancements in computing
  • Innovation across industries
  • Economic impact
• Vacuum tubes


  A device used to control the flow of electric current using a vacuum in a sealed container
• Disadvantages of vacuum tubes

  • Size and weight
  • Warm-up time
  • Heat
  • High power supply voltages
  • Point-to-point wiring
• Solid-state device


  An electronic device in which electricity flows through solid semiconductor crystals rather than through vacuum tubes
• Integrated circuit (IC)


  Transistors and diodes are often combined with resistors, capacitors and other components to create the integrated circuit, a solid-state device that binds the individual components to a thin substrate of semiconductor material
• Large inductors and transformers cannot be fabricated on an IC
• Wafer preparation


  1. Crystal growth

  2. Single Si crystal ingot

  3. Crystal trimming and diameter grind

  4. Flat grinding

  5. Wafer slicing

  6. Edge rounding

  7. Lapping

  8. Wafer etching

  9. Polishing

  10. Wafer inspection
• Oxidation


  The process of adding oxygen to the Si wafer
• Diffusion


  The process of adding impurities atoms from a region with high concentration to a region of low concentration
• Ion implantation


  Introduces impurity atoms in the crystal semiconductor by applying accelerated atoms at a low temperature and high energy
• Chemical-vapor deposition (CVD)


  Used to produce thin film of protective layers on the wafer surface
• Photolithography


  Used to pattern thin films on the substrate by protecting certain areas during successive fabrication processes
• Metallization


  The process of coating a metal layer on the metallic surface or non-metallic surface
• Packaging


  The last stage of the IC fabrication process where the finished silicon wafer or chips are sealed with epoxy or plastic to prevent it from atmospheric dust
• vfBGA Assembly

  Very Fine-pitched Ball Grid Array
• Types of ICs

  • Monolithic
  • Film
  • Hybrid
• Assembly Process Flow


  1. Front of Line (FOL)

  2. Die Preparation

  3. Die Attach

  4. Wire bond

  5. Internal Visual Inspection

  6. End of Line (EOL)
• Monolithic ICs


  ICs that are formed completely within a semiconductor substrate
• Die-prep


  • Wafer Incoming Monitor
  • Wafer Wash
  • Wafer Tape
  • Backgrind
  • Mount Before Detape
  • Wafer Saw
  • Die Visual Inspection
  • Wafer Thickness Monitor

  
• Wafer Incoming Monitor


  • Inspects the wafer to ensure that the wafer has not been damaged during transit
  • To establish an inspection procedure for separation of defect-clustered wafers
• Diffusion method


  A method used to form monolithic ICs
• Rejected dice are marked with inked dots
• Epitaxial


  A method used to form monolithic ICs involving growing a thinly doped epi layer over a thickly-doped silicon substrate
• Film ICs


  ICs where film can only be used as passive circuit components, such as resistors and capacitors
• Thin film


  Fabrication methods include vacuum evaporation and cathode sputtering
• Wafer


  A thin slice of single crystal silicon which is used as the basic substrate for the fabrication of ICs
• Die


  The individual semiconductor element of integrated circuit (also known as chip) or a piece of silicon containing integrated circuit
• Wafer Wash


  Cleans the wafers thoroughly from any foreign materials before covering with tape
• Thick film


  Fabrication method includes screen printing
• Wafer Tape


  Provides tape onto the wafer top surface to prevent any debris or particles from getting in contact with the front side of the wafer during the backgrind process
• Hybrid ICs


  ICs fabricated by combining two or more circuit types, such as film and semiconductor circuits, or a combination of one or more circuit types and discrete elements
• Backgrind


  • Reduces the thickness of the wafer (die backside)
  • Then WASH to ensure no residues of silicon debris is clinging at the back surface of the wafer before detape process
• Wafer De-tape


  The process of removing or peeling off the tape after the backgrind process
• The primary advantage of hybrid microcircuits is design flexibility
• Wafer Thickness Monitor


  • Measures the thickness of the wafer
  • Ensures required thickness is achieved
  • Then WASH to ensure no foreign materials are left on the surfaces of the wafer before wafer mount
• Mount Before Detape (MBD)


  The process of mounting the wafer onto the Nitto tape to hold the wafer in place before cutting or before the wafer is sawn
• Wafer Saw


  To cut the wafer into individual die or the process of separating the dice from the wafer