Material Preparation- Purification, Crystal growth (CZ and FZ process),
Thermal Oxidation- Growth mechanisms, Dry and Wet oxidation, Deal Grove
Diffusion- Fick‘s Laws, Diffusion with constant surface concentration and from
a constant source, diffusion techniques.
Ion implantation-Technique, Range Theory, annealing.
Silicon is the most important semiconductor for the microelectronics industry.
When compared to germanium, silicon excels for the following reasons:
(1) Si has a larger bandgap (1.1 eV for Si versus 0.66 eV for Ge).
(2) Si devices can operate at a higher temperature (150o C vs 100o C).
(3) Intrinsic resistivity is higher (2.3 x 105 Ω-cm vs 47 Ω-cm).
(4) SiO2 is more stable than GeO2 which is also water soluble.
(5) Si is less costly.
The first step in integrated circuit (IC) fabrication is preparing the
high purity single crystal Si wafer. This is the starting input to the fab.
Si wafer refers to a single crystal of Si with a specific orientation,
dopant type, and resistivity.
Typically, Si (100) or Si (111) wafers are used. The numbers (100)
and (111) refers to the orientation of the plane parallel to the surface.
Traditionally, bipolar devices are fabricated in oriented crystals
whereas materials are preferred for MOS devices. Real crystals are imperfect
and contain point defects, line defects or dislocations, area or plane defects, and
The wafer should have structural defects like point defects, line
defects or dislocations, area or plane defects, and volume defects they are in the
order of ppb (parts per billion).
Defects in Si