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Microelectronics - the area of technology and science associated with the fabrication of electronic systems and subsystems using extremely small components. Some of technologies today include:
1. Bipolar
2. MOS metal-oxide-semiconductor
3. thick-film hybrid
4. thin-film hybrid
5. optical waveguides, etc.
Click HERE for the history and development of microelectronics which date back at least 40 years.
Discrete Device Development
The first transistor used in W.W.II was the point-contact transistor made from Tungsten (W) cat whiskers and Germanium (Ge).
Problems IC Considerations
1. Difficult to make consistently yield
2. low power thermal impedance
3. delicate reliability
4. sensitive to environment
The next approach was the alloyed junction transistor. However, the problem with this transistor is the very large base width which reduces the B . Other problems include collector and emitter have the same doping concentrations which reduces the allowed collector supply voltage, etc.
With the Czochralski growth junction there are problems with yield p-type layer thickness.
Planar PN junctions are used with SiO2 masks for diffusions and ion implantions.
Desirable Properties
1. semiconduction
Eg ~ 1eV
Eg ~ insulator
Eg ~ metal
2. electron mobility reasonable ~ 1000 cm2/V-sec
3. planar IC�s, must be able to passivate (masking)
4. must be available and easy handle
| Si | Ge | GaAs | ||
| Eg | 1.12 | 0.69 | 1.43 | eV |
| m n | 1350 | 3800 | 10000 | cm2/sec |
| m p | 500 | 1500 | 250 | cm2/sec |
| passivation | SiO2 | GeO2 Si3N4 | Si3N4 SiO2 | |
| handling | easy | Easy | hard |