1. POWER MOSFET PROCESS AND DEVICE SIMULATION USING SILVACO-TCAD

2. TEAM MEMBERS  SOMITRA BALDUA 120108034  ANMOL RAMRAIKA 120102079  RAJESH KUMAR 120108028  JITENDRA KHATIK 120108016  PRAKHAR TOSHNIWAL 120108026

3. MOSFET---------introduction  The metal–oxide–semiconductor field-effect transistor (MOSFET) is a transistor used for amplifying or switching electronic signals.  In MOSFET,a voltage drop across the oxide induces a conducting channel between the source and drain contacts via the field effect.  The channel can contain electrons (called an nMOSFET or nMOS), or holes (called a pMOSFET or pMOS), opposite in type to the substrate.

4. MOSFET----------------structure( n-MOSFET )

5. BAND-DIAGRAM-------------

6. POWER MOSFET  If the gate-source voltage is at or above what is called the threshold voltage, enough electrons accumulate under the gate to cause an inversion n-type layer; forming a conductive channel across the body region. Electrons can flow in either direction through the channel.  Switching speed is only limited by the rate that charge is supplied to or removed from capacitances in the MOSFET. Therefore switching can be very fast. This is what makes power MOSFETs so efficient at high switching frequency.

7. POWER MOSFET-----structure ( n-channel MOSFET )

8. SIMULATION---------steps involved  Developing a good simulation grid  Defining the initial substrate  Performing epitaxial growth  Performing layer deposition and geometrical etching  Performing ion implantation  Removing implant mask  Performing diffusion  Specification of electrodes

9. 1--------developing a simulation grid  The number of nodes in the grid has a direct influence on simulation accuracy and time. A finer grid should exist in those areas of the simulation structure where ion implantation will occur, where p-n junction will be formed.  In our simulation process,Grid is kept finest in the surface active region of the MOSFET.

10. 2---------developing initial substrate

11. 3---------------epitaxial growth  Using process menu for performing deposition epitaxial layer on gate surface of MOSFET  At the temperature of 1200 degree Celsius for 10 minutes.

12. 4----------------deposition and etching  Oxide, polysilicon and photoresist layers are deposited along with layer thickness  Shape of etch is defined and etching is performed

13. 5-------------------ion implantation

14. 6-------------removing implant mask  Removal of barrier mask by performing etching.  Removing photoresist material by selecting all option to remove the implant mask

15. 7----------------specification of electrodes  Using Structure menu for specifying the location of electrodes so that device can be used by device simulator for electrical characterization.  Aluminium contact is established by deposition and etching beforehand.

16. Tonyplot

17. Device simulation…………  The modelled MOSFET is simulated using Atlas.  Device equations are solved to obtain electrical characteristics of power MOSFET.

18. I-V curve of device

19. Applications of power MOSFET---------  Power MOSFETs with lateral structure are mainly used in high-end audio amplifiers and high-power PA systems.  Power MOSFETs are well known for superior switching speed, and they require very little gate drive power because of the insulated gate. In these respects, power MOSFETs approach the characteristics of an "ideal switch".  The main drawback is on-resistance R DS(on) and its strong positive temperature coefficient.