27-05-2013, 01:07 PM
CMOS inverter with lumped output load capacitance
CMOS inverter.ppt (Size: 3.99 MB / Downloads: 24)
“Building an inverter”
Lithography
Physical structure
CMOS fabrication sequence
Advanced CMOS process
Process enhancements
CMOS technology
An Integrated Circuit is an electronic network fabricated in a single piece of a semiconductor material
The semiconductor surface is subjected to various processing steps in which impurities and other materials are added with specific geometrical patterns
The fabrication steps are sequenced to form three dimensional regions that act as transistors and interconnects that form the switching or amplification network
Lithography
Basic sequence
The surface to be patterned is:
spin-coated with photoresist
the photoresist is dehydrated in an oven (photo resist: light-sensitive organic polymer)
The photoresist is exposed to ultra violet light:
For a positive photoresist exposed areas become soluble and non exposed areas remain hard
The soluble photoresist is chemically removed (development).
The patterned photoresist will now serve as an etching mask for the SiO2
Annealing
After the implants are completed a thermal annealing cycle is executed
This allows the impurities to diffuse further into the bulk
After thermal annealing, it is important to keep the remaining process steps at as low temperature as possible