Surface Potential-Based MOSFET Model

An Advanced Innovative CMOS Model

HiSIM was developed at Hiroshima University, in collaboration with the STARC research center. This model employs the drift-diffusion approximation, correctly modeling the surface potential in the channel.

Conventional MOSFET models often use unphysical parameters to smooth characteristics between the different operation modes. Since HiSIM needs only one set of equations, valid over all modes of operation, only physical parameters are necessary. Therefore, HiSIM is not only accurate, but also reduces the number of parameters needed to model a MOSFET device.

The HiSIM approach results in :

  • No interdependence of major parameters
  • Easy parameter extraction
  • Only 19 parameters needed to model an I-V characteristic
  • Derivatives are continuous over the whole operating range
  • One parameter set for all channel lengths and widths

Physical Effects

HiSIM accounts for the following effects:

  • Short-channel
  • Reverse short-channel
  • Pocket implantation
  • Narrow-channel
  • Quantum
  • Poly-depletion
  • Universal mobility
  • Channel-length modulation
  • Velocity overshoot
  • Symmetry at VDS=0
  • Temperature
  • Intrinsic, overlap fringing capacitances
  • 1/f noise
  • Thermal noise
  • Induced gate noise
  • Noise correlation
  • Gate leakage
  • GIDL
  • Substrate leakage
  • Junction currents and capacitances
  • Shallow trench isolation effects
  • Non quasi-static effects
Gate intrinsic capacitance vs VGS

Surface potentials vs VGS

ID=f(VD) characteristic


Circuit Simulation Examples

HiSIM demonstrates accuracy better than BSIM4 at high simulation speeds. HiSIM is a general purpose model suitable for accurate analog and large circuit simulations over 1 million transistors. Its convergence properties are far better than any other commercial CMOS model.

Key Properties

  • Applicable for state-of-the-art device geometries
  • Efficient operating point calculation for fast simulation times, while maintaining high accuracy
  • Unified description for all bias conditions
  • MOS intrinsic capacitance calculated directly from charges in model
  • No specific parameters for capacitances of MOSFET as with earlier models
  • Complete operation from one set of equations rather than independent equation for different operating bias conditions
  • Binning option to model new physical effects not yet accounted for in the model equations
Example 1: HiSIM simulation shows good accuracy
Example 2: DAC 90nm circuit functionality

Example 3: 2k RAM circuit


Silvaco Implementation

  • HiSIM is compatible with VZERO and BYPASS options in order to achieve greater speed performance
  • HiSIM is ready to be used on parallel computer architectures
  • Internal warnings and diagnostics provide valuable information to help find convergence issues
  • Device internal variables (currents, conductances, charges...) can easily be accessed like any other parameter

Rev. 012014_05