Numerical Boltzmann/Spherical Harmonic Device CAD Overview and Goals Overview: Further develop and apply the Numerical Boltzmann/Spherical Harmonic method of advanced device simulation. The method is based on the direct solution to the Boltzmann equation. It promises to be applicable at and below the 0.1µm range, where drift- diffusion models become inaccurate. It gives virtually the same information as Monte Carlo simulations (device distribution function) and is 1000 times faster. Goals: Develop and apply new simulator to model deep submicron behavior: - Terminal characteristics (I-V) - Substrate current (impact ionization)
Transcript
Numerical Boltzmann/Spherical Harmonic Device CAD Overview and Goals
Overview:Further develop and apply the Numerical Boltzmann/Spherical
Harmonic method of advanced device simulation. The method is based on the direct solution to the Boltzmann equation. It promises to be applicable at and below the 0.1µm range, where drift-diffusion models become inaccurate. It gives virtually the same information as Monte Carlo simulations (device distribution function) and is 1000 times faster.
Goals:Develop and apply new simulator to model deep submicron behavior:- Terminal characteristics (I-V)- Substrate current (impact ionization) - Oxide injection, gate leakage current and FLASH programming- Quantum effects
Numerical Boltzmann/Spherical Harmonic Device CAD Benefit to Intel
1) The semiconductor community recognized the benefit of the Numerical Boltzmann model by including it in the 1997 SIA Roadmap as one four approaches to be pursued for future device design.
2) Since Numerical Boltzmann/Spherical Harmonic is based on fundamental transport physics, it should be reliable for design of ultra-small transistors (<0.15µm), where the drift-diffusion model becomes less and less accurate.
3) Gives virtually a complete device description (like Monte Carlo), and is practical enough for day-to-day design. Applied to short channel and hot-electron effects: velocity overshoot, impact ionization, oxide tunneling, thermal emission.
4) The model will be useful for predicting the limits of MOSFET scaling, especially related to oxide thicknesses, reliability and optimized doping, as well as future devices (SOI, double gate MOSFETs, etc.).
Numerical Boltzmann/Spherical Harmonic Device CAD Scheduled Deliverables: First Year (98-99)
All deliverables for first year were achieved.
1) Benchmark Boltzmann solver for deep submicron MOSFET: Achieved
2) Deliver and install Boltzmann solver at Intel: Achieved
3) Improve energy space discretization for better convergence: Achieved
4) Benchmark to determine need for higher order spherical Achieved harmonics:
5) Develop thin oxide gate leakage current model: Achieved
Numerical Boltzmann/Spherical Harmonic Device CADScheduled Deliverables: 2nd Year (1999-2000)
1) Incorporate quantum mechanical effects. Two Approaches: a) Boltzmann/Wigner method, Stage 1: Achievedb) Schrodinger, Stage 1: Achieved
2) Develop transient and frequency domain capabilities: Achieved 3) Adapt and apply Numerical Boltzmann to SOI devices. Achieved
4) Develop thin oxide degradation model based on electron In Progress and hole transport:
5) Develop Numerical Boltzmann simulator for PMOS: Achieved
Numerical Boltzmann/Spherical Harmonic Device CADScheduled Deliverables: 3nd Year (2000-2001)
1) Continue incorporation of quantum mechanical effects. a) Using Boltzmann/Wigner method. Achievedb) Using Boltzmann/Schrodinger method Achieved
2) Continue to apply to devices with geometries of 0.1 µm and Achieved below, with focus on thin oxides.
3) Improve user friendliness so Numerical Boltzmann can be Achieved easily transported into Intel’s TCAD platform, especially with respect to Suprem. 4) Explore boundary conditions at source and drain In progress
5) Apply to futuristic nonconventional devices In progress
Start
Input from SUPREM
Sort Data
Interpolate to Rectangular Grid
Smoothen Doping Profile
Simulator
END
Flow Chart Doping Profile After Interpolation
Doping Profile after DD Simulation
Numerical Boltzmann/Spherical Harmonic Device CAD
Numerical Boltzmann/Spherical Harmonic Device CAD Results: Device Structure and Distribution Function
Y=0.0001m Y=0.4mDistribution Function
Electron Concentration MOS Cross Section
Numerical Boltzmann/Spherical Harmonic Device CAD Results: Benchmark I-V with Experiment
Doping Profile Leff = 0.88m
Leff = 0.35m Leff = 0.15m
Numerical Boltzmann/Spherical Harmonic Device CAD Results: Impact Ionization and Substrate Current
Generation Rate Agreement with experiment: No fitting parameters!
1)The Numerical Boltzmann/Spherical Harmonic device simulation tool has been has been designed and developed into a state of the art TCAD simulator.
2) Since Numerical Boltzmann/Spherical Harmonic is based on fundamental transport physics, it is especially useful for design of ultra-small transistors (<0.10µm), where the drift-diffusion model becomes less and less accurate.
3) Gives virtually a complete device description (like Monte Carlo), and is practical enough for day-to-day design. Applied to short channel and hot-electron effects: velocity overshoot, impact ionization, oxide tunneling, thermal emission and quantum confinement.
4)The Numerical Boltzmann/Spherical Harmonic simulator has been transferred to Intel. It is compatible with Suprem doping and should be ready for incorporation into Intel’s TCAD platform.
