ECAD is concerned with the design of an integrated circuit in terms
of schematics, netlists, and layout.
An integrated VLSI circuit consists of up to several millions
of active devices that are interconnected on a chip to
implement the desired functions, i.e., to build a memory module
or a microprocessor.
The layout contains a description of the entire integrated circuit,
including all active devices and interconnect structures, in
terms of material layers
.
Circuit simulation uses a netlist of the circuit, together with
compact models of the electrical components, to compute the
behavior of the integrated circuit. Model parameters
are extracted
from device data obtained from measurements or from simulation.
Some parameters - mostly concerned with interconnects - can be
directly inferred from the layout.
The output of circuit simulation is used to verify the entire design.
From the layout, lithography masks are generated to be used in
fabrication and process simulation.