Every software package contains a full set of examples suitable for that version and are installed with the software. If you see examples here that are not in your installation you should consider updating to a later version of the software. These examples can be used by beginners and advanced users for product evaluation, teaching purposes, and self-training.
Required Modules
Victory Device
- 2D Simulator
This example shows how reduced poly doping can result in depletion occurring in the poly gate under bias. This undesirable effect shows up in Capacitance-Voltage (C-V) curves as anomalies in the shape of the plot.
Reduced poly doping in a MOSFET with a thin gate can reduce drain current drive and increase the threshold voltage, since some of the voltage that should be dropped across the gate oxide is now dropped across the depletion region.
The usual causes of reduced doping in the poly are counter doping process flows, insufficient source-drain implant dose, and evaporation of dopant during thermal anneals due to the lack of a capping oxide.
Three simulations are run with the P+ poly gate doped to a concentration of 1e19/cm3, 1e20/cm3 and 1e21/cm3. The effect on the capacitance curves is then observed through overlaying the three cases.
It will be observed that even for a poly gate doped to 1e20/cm3, depletion occurs in the poly gate giving anomalous C-V characteristics. This can have serious consequences if the maximum value from the C-V curve is used to measure the thickness of the gate oxide.
The three simulations are run sequentially for simplicity sake. Alternatively, the simulation could be parameterised and a LOOP used to sweep the parameters.
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