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

The example shows :
How to set up a SANOS device (variant of a SONOS device)

How to obtain the threshold Voltage of a SANOS device

How to obtain data for a range of Biases and time frames

The blocking insulator need not be made of the same material as the tunnelling insulator. In this case we have a blocking insulator made of Sapphire (Al203) and a tunnelling insulator made of Silicon dioxide.

This example uses the DBINTERNAL feature of Deckbuild, the auxiliary deck is run for each value of the Gate Bias specified by the parameter sweep of vgate in the main deck.

Each time the auxiliary deck is run, it sets up a SANOS structure, with the blocking insulator layer made of Sapphire. It is necessary to make this material into a widegap semiconductor and set other parameters on the MATERIAL statement.

Because of the relatively low conduction band offset between the Silicon Nitride and the sapphire, the INTERFACE S.S THERMIONIC statement is used to model any thermionically emitted current leaving the device. This current will not appear in the SONOS outcurrent, but in the gate conduction current.

In the NITRIDECHARGE statement, we set up the relevant parameters and also specify PF.BARRIER. This sets the barrier height for the Poole-Frenkel detrapping model, which is enabled by the PF.NITRIDE flag on the MODELS statement.

The gate bias is ramped and the device charged for 1 second. A structure file is saved out at various preset charging times. The next part of the deck reads in these structure files in turn, and for each one it ramps the drain bias and also the gate bias in order to extract the threshold voltage. The gate stack layers are treated as insulators in this case, to make the simulation simpler. The charge trapped in the Nitride layer affects the threshold voltage in the same way.

After calculating the threshold voltage for the set of Gate biases and at each of the preset charging times, the threshold data is plotted. The threshold voltage increases with Gate Bias and also with charging time. For a charging time of 1.0 seconds there is a roughly linear relationship between gate bias and threshold voltage (0.65 V of threshold voltage change for every 1.0 V of bias voltage change). The threshold voltage for the uncharged device is also shown, and threshold voltage shifts can be calculated relative to this.

Images