The 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.
- Wafer Production– wafer– a thin, circular slice of semiconductor material
- Polycrystalline silicon is heated to a molten liquid and a small piece of semiconductor material is planted on top
- 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
- The ingot is then ground to be even all around, and a diamond saw cuts the wafers into slices
- The wafer is processed to become lustrous and shiny
- The wafers are then sent to manufacture integrated circuits
- Oxidation
- Wafers are pre cleaned by using low particle chemicals
- Heated and exposed to pure oxygen and created a silicon dioxide film on the surface
- Creates a smooth thickness on the top
- Masking– photolithography* or photo-masking*
- Light sensitive film is applied to wafer
- The wafer lines up to a photo aligner and projects a light through the mask and exposes the photoresist with the mask pattern
- Etching –
- Exposed photoresist is removed and backed to a harden the pattern
- A plasma is introduced so the non-covered areas are etched away
- The photoresist is removed, and the wafer is checked
- Doping-
- P-Type (Boron/Gallium) are added to alter electrical characteristic of semiconductor material
- N-Type (Phosphorus/Arsenic) are added to alter electrical characteristic of semiconductor material
- Repeat Steps
- Steps 1- 6 are repeated until “front end” layer is done
- Metallization and Dielectric Deposition
- Layers are interconnected by using insulators and metal depositions
- 3 metal layers: 1 dielectric
- Layers are interconnected by using insulators and metal depositions
- Passivation
- Last metal layer an dielectric layer is deposited to protect circuit from problems
- Openings are etched to access top layer by probes and wire bonds
- Electrical Test
- Computer driven tests checks the chip on each wafer
- The ones that do not pass are inked
- Assembly
- Diamond saw slices wafers into chips are inspected via microscope
- Wafers are packaged and then wires are attached
- Coated in plastic, tested again