Juan Pablo Duarte

Negative Capacitance in Short-Channel FinFETs Externally Connected to an Epitaxial Ferroelectric Capacitor

We report subthreshold swings as low as 8.5 mV/decade over as high as eight orders of magnitude of drain current in short-channel negative capacitance FinFETs (NC-FinFETs) with gate length Lg = 100 nm. NC-FinFETs are constructed by connecting a high-quality epitaxial bismuth ferrite (BiFeO3) ferroelectric capacitor to the gate terminal of both n-type and p-type FinFETs. We show that a self-consistent simulation scheme based on Berkeley SPICE Insulated-Gate-FET Model:Common Multi Gate model and Landau-Devonshire formalism could quantitatively match the experimental NC-FinFET transfer characteristics. This also allows a general procedure to extract the effective S-shaped ferroelectric charge-voltage characteristics that provides important insights into the device operation.

BSIM—SPICE Models Enable FinFET and UTB IC Designs

Two turn-key surface potential-based compact models are developed to simulate multigate transistors for integrated circuit (IC) designs. The BSIM-CMG (common-multigate) model is developed to simulate double-, triple-, and all-around-gate FinFETs and it is selected as the worlds first industry-standard compact model for the FinFET. The BSIM-IMG (independent-multigate) model is developed for independent double-gate, ultrathin body (UTB) transistors, capturing the dynamic threshold voltage adjustment with back gate bias. Starting from long-channel devices, the basic models are first obtained using a Poisson-carrier transport approach. The basic models agree with the results of numerical two-dimensional device simulators. The real-device effects then augment the basic models. All the important real-device effects, such as short-channel effects (SCEs), quantum mechanical confinement effects, mobility degradation, and parasitics are included in the models. BSIM-CMG and BSIM-IMG have been validated with hardware silicon-based data from multiple technologies. The developed models also meet the stringent quality assurance tests expected of production level models.

BSIM6: Analog and RF Compact Model for Bulk MOSFET

BSIM6 is the latest industry-standard bulk MOSFET model from the BSIM group developed specially for accurate analog and RF circuit designs. The popular real-device effects have been brought from BSIM4. The model shows excellent source-drain symmetry during both dc and small signal analysis, thus giving excellent results during analog and RF circuit simulations, e.g., harmonic balance simulation. The model is fully scalable with geometry, biases, and temperature. The model has a physical charge-based capacitance model including polydepletion and quantum-mechanical effect thereby giving accurate results in small signal and transient simulations. The BSIM6 model has been extensively validated with industry data from 40-nm technology node.

Recent enhancements in BSIM6 bulk MOSFET model

In this paper, we discuss the recent enhancements made in the BSIM6 bulk MOSFET model. BSIM6 is the latest compact model of bulk MOSFET from BSIM group which have body referenced charge based core. Junction capacitance model is improved over BSIM4 and is infinitely continuous around Vbs=Vbd=0V. Symmetry of the model is successfully validated by performing Gummel Symmetry Test (GST) in DC and symmetry test for capacitances in AC. Self heating model is also included in BSIM6 and test results are reported. Model capabilities are compared against an advanced 40nm CMOS technology and it is observed that simulated results are in excellent agreement with the measured data.

Unified FinFET compact model: Modelling Trapezoidal Triple-Gate FinFETs

A unified FinFET compact model is proposed for devices with complex fin cross-sections. It is represented in a normalized form, where only four different model parameters are needed. The proposed model accurately predicts the current-voltage characteristics of different FinFETs structures such as Double-Gate (DG), Cylindrical Gate-All-Around (Cy-GAA), or Rectangular Gate-All-Around (Re-GAA) FinFETs. In addition, for the first time, Trapezoidal Triple-Gate (T-TG) FinFETs are accurately modelled. Short-Channel-Effects (SCE) sub-models have been also implemented in the presented work. The model has been verified with TCAD data.

Modeling of GaN-Based Normally-Off FinFET

In this letter, a macromodel for normally-off (enhancement mode) AlGaN/GaN-based FinFET (2-DEG channel at top with two MOS like sidewall channels) is proposed. AlGaN/GaN-based FinFET devices have improved gate control on the channel due to additional sidewall gates compared with planar structures, but device characteristics exhibit strong nonlinear dependence on fin-width. The proposed model captures both 2-DEG and sidewall channel conduction as well as the fin-width dependency on device characteristics. Model shows excellent agreement with state-of-the-art experimental data.

Capacitance Modeling in III–V FinFETs

We present a physics-based model of charge density and capacitance for III-V channel double-gate nMOSFETs. The developed model accurately accounts for the impact of quantum capacitance on gate capacitance with applied gate voltage including the steplike behavior with sub-band population. The presented model is in excellent agreement with the self-consistent Schrödinger-Poisson simulation data of InGaAs channel double-gate MOSFET.

RF Modeling of FDSOI Transistors Using Industry Standard BSIM-IMG Model

In this paper, RF modeling and step-by-step parameter extraction methodology of the BSIM-IMG model are discussed with experimental data. BSIM-IMG is the latest industry standard surface potential based model for fully depleted silicon-on-insulator (FDSOI) transistors. The impact of gate, substrate, and thermal networks is demonstrated with S-parameter data, which enable the BSIM-IMG model to capture RF behavior of the FDSOI transistor. The model is validated over a wide range of biases and frequencies and excellent agreement with the experimental data is obtained.

Unified Compact Model Covering Drift-Diffusion to Ballistic Carrier Transport

In this letter, we present a unified compact model, which accurately captures carrier transport from the drift-diffusion to ballistic regime. This is a single unified model, which accounts for carrier degeneracy effects in ballistic transport. The model is implemented into the industry standard compact models for FinFETs, fully depleted silicon-on-insulator (FDSOI) devices and bulk MOSFETs: 1) Berkeley Spice model for common multi-gate; 2) Berkeley Spice model for independent multi-gate; and 3) BSIM6. The model is validated with experimental data and TCAD simulations for FDSOI devices, FinFETs, and bulk MOSFETs.

Compact models of negative-capacitance FinFETs: Lumped and distributed charge models

This work presents insights into the device physics and behaviors of ferroelectric based negative capacitance FinFETs (NC-FinFETs) by proposing lumped and distributed compact models for its simulation. NC-FinFET may have a floating metal between ferroelectric (FE) and the dielectric layers and the lumped charge model represents such a device. For a NC-FinFET without a floating metal, the distributed charge model should be used and at each point in the channel the ferroelectric layer will impact the local channel charge. This distributed effect has important implications on device characteristics as shown in this paper. The proposed compact models have been implemented in circuit simulators for exploring circuits based on NC-FinFET technology.