modeling Low-Voltage Power MOSFET

powerex12.in : modeling Low-Voltage Power MOSFET

Requires: SSuprem 4/DevEdit/S-Pisces
Minimum Versions: Athena 5.22.3.R, Atlas 5.28.1.R

This example demonstrates modeling of Low-Voltage Power MOSFET based on the following reference:

K.Shenai, C.Cavallaro, S.Musumeci, R. Pagano, A.Raciti "Modeling Low-Voltage Power MOSFETs as Synchronous rectifiers in Buck Converter Applications", Industry Applications Conference, 2003. 38th IAS Annual Meeting pp. 1794- 1801 vol.3.

It shows:

  • Structure definition using Athena
  • Remeshing using DevEdit
  • Transfer and Breakdown Voltage Characteristics using Atlas
  • Output and AC small signal Characteristics using Atlas

The file starts with the definition of the process flow for a low voltage MOSFET transistor in Athena. Often a mesh that is used for process simulation, is not optimal for use with device simulation. In this example, the mesh generation tool DevEdit is used to recreate a mesh that has zero obtuse triangles in the semiconductor region. It is then refined as a function of a number of solution quantities on the mesh (eg: Nte Doping).

Popup windows under the DeckBuild Command window can be used to create this set of commands to control DevEdit. The DevEdit GUI can be used as well by loading the structure file from Athena, remeshing it using DevEdit GUI and saving a DevEdit command file. The mesh syntax from this file can then be copied and pasted into deckbuild.

In Atlas the transfer characteristic is simulated by setting the Drain Voltage to 25V and ramping the Gate Voltage to 4V. The Threshold Voltage is adjusted using the workf parameter from the contact statement.

In order to simulate the Breakdown Voltage, the initial Athena structure has been modified by providing the body region with a contact, thus, ensuring a short with the source region. This is done directly in Atlas by adding a body contact using the electrode name=body x.min=0 x.max=0 y.min=0.3 y.max=0.6 statement. The breakdown Voltage can be adjusted using the parameter AN2 from the impact statement. To simulate the breakdown curve, the drain electrode is ramped until the current reaches a specified compliance value.

solve vstep=1 vfinal=30 name=drain cname=drain compliance=1

The output characteristic is obtained by ramping the Gate Voltage to the desired value and then ramping the drain voltage from 0V to 5V. The log off statement allows us to save multiple log files.

The body-drain diode behavior has also been simulated. The forward characteristic is dependent on the drain and dource contacts resistance as well as the epi-layer resistance. A drain contact resistance is added using the statement contact name=drain resist=5e03 .

The capacitances are collected by applying a bias ramp on the drain electrode up to 15V. The parameter ac on the solve statement sets the ac analysis on. The frequency of this signal is set to 1MHz.

To load and run this example, select the Load button in DeckBuild > Examples. This will copy the input file and any support files to your current working directory. Select the Run button in DeckBuild to execute the example.