US 10,769,339 B1 · Local band-to-band-tunneling model for TCAD simulation

Abstract

An improved local modeling function for estimating band-to-band tunneling currents RBBT in nanodevices and other low-voltage circuit elements during TCAD simulation, the model being represented by the equation: R B ⁢ B ⁢ T = - B ⁢  F  σ = exp ⁡ ( - F 0  F  ) ⁢ g where terms B, F, F0 and σ correspond to conventional terms used in Hurkx-based equations, and the term g is an exponential factor determined by the equation: g = ( F - F 1 F 1 ) 1 . 5 where the term F1 is the built-in electric field at a selected cell/point determined by the equation: F 1 = max ⁡ ( F ˜ 1 , C ⁢ 2 ⁢ q ⁢ E g ⁢ N n ⁢ e ⁢ t ɛ ) where {tilde over (F)}1 is the built-in electric field at zero bias, q is fundamental electronic charge, C is a fitting parameter, Eg is bandgap, Nnet is doping concentration, and E is dielectric constant. At low applied fields (F˜F0) the factor g biases the improved model toward the zero-field/zero-current origin in a way that closely matches non-local model results. At higher applied fields the factor g has less influence and the model is controlled by the conventional terms.

Claims20

Dependent claims

A computer implemented method for estimating a band-to-band tunneling (BBT) current in a circuit element, the method comprising:

generating, by a processor, a model of the circuit element including a plurality of cells, wherein each cell includes position data and material data corresponding with an associated portion of said circuit element such that said position data defines a spatial position of said each cell within said model corresponding to a spatial positional of said associated portion, and such that said material data operably defines a material composition and corresponding electrical characteristics of said associated portion of said circuit element;
simulating operation of the circuit element including applying a simulated external electric field to a selected cell of said plurality of cells;
and
utilizing a local BBT modeling function to generate a BBT current estimate, the local BBT modeling function including an exponential factor having a value determined by a difference between said external electric field and a built-in electric field at said selected cell and raised to an exponential power greater than one,
wherein the built-in electric field is calculated using said position data and said material data of said plurality of cells,
wherein said local BBT modeling function implements said exponential factor such that the BBT current estimate becomes zero when the external electric field is equal to the built-in electric field.

3 more elements

In an electronic design automation (EDA) tool implemented in a computer, a Technology Computer-Aided Design (TCAD) toolset configured to estimate band-to-band tunneling (BBT) current in a circuit element, said TCAD toolset including instructions that, when executed by a processor of said computer, cause the processor to perform operations comprising:

generating a model of the circuit element including a plurality of cells, wherein each cell includes position data and material data corresponding with an associated portion of said circuit element such that said position data defines a spatial position of said each cell within said model corresponding to a spatial positional of said associated portion, and such that said material data operably defines a material composition and corresponding electrical characteristics of said associated portion of said circuit element;
simulating operation of the circuit element including applying a simulated external electric field to a selected cell of said plurality of cells;
and
utilizing a local BBT modeling function to generate a BBT current estimate, the local BBT modeling function including an exponential factor having a value determined by a difference between said external electric field and a built-in electric field at said selected cell and raised to an exponential power greater than one,
wherein the built-in electric field is calculated using said position data and said material data of said plurality of cells,
wherein said local BBT modeling function implements said exponential factor such that the BBT current estimate becomes zero when the external electric field is equal to the built-in electric field.

3 more elements

Dependencies are inferred from the claim text.

Local band-to-band-tunneling model for TCAD simulation

Life of this patent

Local band-to-band-tunneling model for TCAD simulation

Life of this patent

Abstract

Claims20