GLOBALFOUNDRIES is a company that fabricates the wafers according to customer needs. Basically, they "print" the millions of transistors and integrated circuits on the wafer.


Typical sequence in a chip manufacturing process


1) Film deposition & polishing
2) Photolithography
3) Etch & resist strip
4) The above processes are repeated n times (n=number of layers of the chip)

Film deposition & polishing

1) The wafer has to be cleaned before deposition in order to prevent contamination. This process whereby the wafer is rinsed with various chemicals such as hydrochloric acid, sulfuric acid and ammonium hydroxide.
2) The wafer has to enter to furnace for film deposition asap as the wafer has to be cleaned again if it did not enter the furnace 2 to 4 hours after it is being cleaned.
3) The chemical process that takes place inside the furnace is the oxidation of silicon where silicon combines with oxygen and water at high temperature to form silicon dioxide (glass).

Photolithography

1) A layer of photoresist is being coated on the silicon dioxide layer.
2) The layer of photoresist is then exposed to ultraviolet light with a patterned reticle.
3) The places where the photoresist is exposed will develope can be removed.


Etch & resist strip

1) Fluorocarbon gases such as CF4, CHF3, CH3F are used for etching silicon wafers.
2) They are heated until they become plasma before they are used for etching.
3) During etching the wafer is exposed to plasma until the areas of silicon dioxide which is not covered by the photoresist is removed.
external image photolithography.gif

The above processes are then repeated numerous times until the required number of layers are completed