Manufacturing of Semiconductor

semiconductor-manufacturingThe creation of semiconductors involves a multitude of steps. Some can be intricate involving multiple stages of testing, while others can be as simple as gluing a few pieces together. Below are listed steps and definitions of how a semiconductor is made.  Fabrication can take anywhere from 10 days to a month.

semiconductor-manufacturing2

  1. Wafer Productionwafer– a thin, circular slice of semiconductor material
    1. Polycrystalline silicon is heated to a molten liquid and a small piece of semiconductor material is planted on top
    2. Then the “seed” is pulled from the melted liquid and cools to form growth connecting the two. The shape is like a needle sticking out of a upside down cup
    3. The ingot is then ground to be even all around, and a diamond saw cuts the wafers into slices
    4. The wafer is processed to become lustrous and shiny
    5. The wafers are then sent to manufacture integrated circuits

 

  1. Oxidation
    1. Wafers are pre cleaned by using low particle chemicals
    2. Heated and exposed to pure oxygen and created a silicon dioxide film on the surface
    3. Creates a smooth thickness on the top

 

  1. Masking– photolithography* or photo-masking*
    1. Light sensitive film is applied to wafer
    2. The wafer lines up to a photo aligner and projects a light through the mask and exposes the photoresist with the mask pattern

 

  1. Etching –
    1. Exposed photoresist is removed and backed to a harden the pattern
    2. A plasma is introduced so the non-covered areas are etched away
    3. The photoresist is removed, and the wafer is checked

 

  1. Doping-
    1. P-Type (Boron/Gallium) are added to alter electrical characteristic of semiconductor material
    2. N-Type (Phosphorus/Arsenic) are added to alter electrical characteristic of semiconductor material

 

  1. Repeat Steps
    1. Steps 1- 6 are repeated until “front end” layer is done

 

  1. Metallization and Dielectric Deposition
    1. Layers are interconnected by using insulators and metal depositions
      1. 3 metal layers: 1 dielectric

 

  1. Passivation
    1. Last metal layer an dielectric layer is deposited to protect circuit from problems
    2. Openings are etched to access top layer by probes and wire bonds

 

  1. Electrical Test
    1. Computer driven tests checks the chip on each wafer
    2. The ones that do not pass are inked

 

  1. Assembly
    1. Diamond saw slices wafers into chips are inspected via microscope
    2. Wafers are packaged and then wires are attached
    3. Coated in plastic, tested again