The Isolation Module generates a parametrized shallow trench isolated (STI) twin-tub structure for studies of its isolation properties.
Latchup analysis is carried out by ramping up the power supply voltage in a transient simulation. Automatic timestep control provides the necessary time resolution. The breakdown voltage is extracted and can be characterized as a function of geometry and doping. Required STI depth and width for a given N- and P-Well configuration and specified latchup voltage can be determined.
Manufacturability is studied and optimized by considering the effects of misalignment on breakdown voltage.
The structure and doping are completely parametrized. STI depth, width and sidewall angles are adjusted using parameter values.
This simulation analyzes a cross-section trough a basic CMOS inverter circuit:
The cross-section under consideration is shown below:
Isolation Structure as a 3D surface projection plot, doping concentration and surface color corresponds to log10(Net):
Electric potential at the start of the VDD ramp:
Electron concentration:
Hole concentration:
Breakdown current-voltage curves, N-Well misalignment is the parameter:
Breakdown voltage versus N-Well misalignment, asymmetric response is observed:
