SOURCE: Silicon can be found abundantly on earth, 25 % of earth's crust is silicon. However it needs purification and crystallization before it can be used for microelectronics. The starting material is sand: SiO₂. The methods used are: Czochralski (picture below)or floating zones techniques.

STEP 1: Fabrication of polycrystalline silicon by heating sand until 2000oC.

                    Reaction: SiC + SiO₂ = Si + SiO + CO

STEP 2: The poly-Si is melted again to produce electronic grade monocrystalline silicon. Pure silicon tube named ingot is fabricated by pulling and rotating a pure Si seed from the molten poly-Si bath in the presence of HCl (Picture 1). The diameter of ingot is determined by the pulling speed. The ingot is cooling down while it's pulled out from the melted bath.

Picture 1. Czochralski method

STEP 3: Purification in order to become electronic grade Si

STEP 4: Grinding in order to make the primary and secondary flaps necessary for orientation recognition.

STEP 5: Cutting with a diamand saw, in order to define thickness and surface orientation (<111>) by slicing under an angle

STEP 6: Lapping in order to insure flat substrates and parallel surfaces

STEP 7: Etching in nitric acid/ acetic acid or sodium hydroxide to remove cracks from lapping

STEP 8: Polishing by CMP for a smoother surface

STEP 9: Final clean

STEP 10: Inspection ( for O and C concentrations, gettering)