This page updated 01 March 2015

Facts & Features

Input data:

Vertical impurity profiles for active region (emitter - base - collector), collector sinker, extrinsic base, P+ isolation. These can be supplied in analytic form as the sum of superimposed quasi-gaussian functions (this combination can provide excellent fits to almost any impurity distributions), or for the active region, in tabular format from the output of process simulators (or measured process data) (conversion interfaces are available for certain software). The impurity profile for each region may be visually verified with BIPGRAPH post-processor graphics in each of the four vertical regions. In many cases, only the active region profile need be specified.

BIPOLE3 accepts mask template dimensions for emitter, base, extrinsic base, collector sinker, P+ isolation spacing and buried layer, for rectangular geometry devices (single or double base contact). Visual graphics verification of most mask layouts is available. In addition, circular geometry emitter devices and interdigitated structures are also handled.

Physical model data:

Comprehensive physical models including most of the recently published work are available for: band- gap Eg versus temperature, mobility versus doping and temperature, band-gap narrowing (BGN) and recombination lifetime versus doping and temperature. User adjustable parameters are available for all models. BIPGRAPH plots are available of mobility, BGN and lifetime versus doping, with temperature as an input parameter (refs. [3, 4, 6, 19, 24-33]).

Numerical Simulation Method

The BIPOLE3 bipolar device simulation program [1], [2], is based on the modified Variable Boundary Regional Approximation (VBRA). In the vertical 'x' direction (emitter - base - collector), the device is divided into 5 regions: quasi-neutral emitter, 2 - emitter-base space charge layer, quasi-neutral base, base-collector space charge layer, neutral collector. In the three quasi neutral regions, Poisson's equation is not solved; only the transport and continuity equations are solved. However, normalised space charge is computed and monitored to determine the quasi-neutral region boundary. The Poisson solutions in the space charge regions include free carriers and field dependence of carrier velocity. This de-coupling of the transport and Poisson's equation gives very fast execution times in the vertical one dimensional solution. Poisson's equation in quasi-cylindrical co-ordinates is solved in the junction sidewall regions to determine sidewall capacitance and breakdown voltage. A separate coupled 2D simulation determines sidewall injected current and minority carrier charge.

The horizontal majority carrier current flow simulation uses a bias dependent integrated conductivity (computed during the vertical simulation) to determine total current, charge and capacitance values and hence to extract the electrical terminal characteristics.

An overview of the numerical scheme, including Extension Modules is given in the attached document.

Bias ranges:

BIPOLE3 accepts a user defined value for Vcb and automatically scans the useful Ic current range, In addition the user may define the minimum and maximum values of Vbe to override the default range of values. In addition, the user may request multiple runs scanning also a range of Vcb values, to generate Ic-Vce 'curve-tracer' characteristics.

Output:

By default, BIPOLE3 generates all major terminal characteristics (Ic & Ib Gummel plots, beta vs Ic, ft vs Ic, fmaxosc vs Ic, ECL propagation delay time vs Ic, Rb and Rc versus Ic. These may be visualized with the BIPGRAPH graphics post-processor or inspected as tables in a .lst file.

Many useful process related quantities are computed, such as sheet resistances for each layer, Gummel integrals (including and excluding BGN and mobility). Values of plane and sidewall capacitance are computed separately for the e-b, b-c and c-s junctions.

Many plots of internal quantities are available automatically. These include: junction capacitances versus bias voltage, vertical current density Jn and Jp versus internal Vbe, emitter injection and total components of vertical b vs Jn, vertical delays in each of emitter, base, b-c space charge regions versus Jn.

The following plots are also available:

Avalanche multiplication factor 'M' vs bias, Early voltages (VA, VB) vs bias. Plots of carrier concentrations, electric field, potential are available at a selected current density in the vertical direction. Two dimensional contour plots (PC version and limited UNIX versions) are available for minority carrier concentration under the emitter at a given value of Ic. 'Curve tracer' Ic vs Vce characteristics may also be generated automatically but with increased execution time.

SPICE Gummel-Poon model parameters may be optionally extracted using the SPI Extension Module as described below.

Special features:

BIPOLE3 simulation includes: polysilicon emitter BJTs (including tunneling through the interface oxide), SiGe HBTs with user defined Ge(x) profile distributions, Non-Equilibrium transport solution for shallow collectors with low BVceo, trap assisted tunnel model for heavily doped emitter-base sidewalls, photogeneration of carriers for diode simulations. Templates for Double poly double self aligned structures are also available.

Ease of Use:

Execution time (for one Vcb and a range of Vbe bias values) is less than 1 sec for most simulations on a Windows 8 desktop. Setting up input files is particularly easy; the package contains files for many examples of typical industrial devices. These can be used as a starting point and the Reference Manual and Tutorial Guide provide comprehensive details for facilitating use of the software.

Bipole3 Extension Modules

These modules extend the capability of BIPOLE3. Provided the modules have been loaded, they are accessed simply by the use of one or several additional parameters in the BIPOLE3 input file. From a user point of view they are thus accessed seamlessly.

SPI Extension Module for Spice parameter extraction

SPI is an Extension Module which combines information obtained during numerical simulation of the BJT/HBT on real physical parameters (such as IS) with sophisticated post-processor fitting techniques. Reference [55] The result is highly accurate and rapid SPICE file generation. The accuracy of the SPICE parameter extraction may be observed visually using BIPGRAPH where Bipole3 simulated and SPICE generated curves are superimposed for Ft, current gain, Ic and Ib versus Vbe. Numerical accuracy of the various parameters extracted is also recorded in the output .lst file. VBIC95 SPICE parameter options are also available. See SPICE extraction example in section 6.1 of the (downloadable) Tutorial Guide.

Execution time is only increased marginally thus making this Extension Module extremely attractive for chip design and optimisation.

BIP2NEUT Extension Module for 2D sidewall injection

The quasi neutral sidewall region in a vertical NPN structure is accurately simulated at low Vbe values from a full 2D minority carrier simulation using the BIP2NEUT Module. This computes total sidewall injected current and charge. This is subsequently used in normalised form at higher Vbe bias values thus allowing total current and charge to be extracted for dc and high frequency terminal characteristics. The absolute precision of the simulated results for these usually second order effects diminishes for collector currents much higher than that corresponding to peak ft. However the precision is adequate for most engineering purposes (i.e. within the normal bias range for which the transistor is designed).

The resulting electrical characteristics are extremely accurate for Vbe bias up to and including peak ft and in general the BIPOLE3 electrical terminal characteristics (including ft) are in excellent agreement with measured data well above the ft fall-off region.

It should be noted that in some respects the Bipole3 computed terminal characteristics are more accurate than those generated from ‘full 2D’ simulations since all components of current, minority carrier charge and junction capacitances (i.e. for the complete emitter perimeter and complete collector and P+isolation areas and perimeters) are included in the simulations for the given mask layout, including oxide walled and related options.

This Extension Module also allows analysis of the quasi neutral emitter region of a vertical NPN transistor and gives a complete analysis of the lateral PNP transistor (a highly two dimensional current flow device).

The Bipole3 Tutorial Guide section 6.2 gives examples of the use of the Bip2neut Extension Module and illustrates the improved accuracy available in ft predictions when using the Bip2neut module.

MOSCALC Extension Module

This Extension Module has been added to provide prototype simulation for MOSFET structures. It uses numerical solutions for horizontal and vertical semiconductor equations to generate internal physical plots for electric field, carrier concentrations, etc. and plots for the terminal characteristics.

This module is included in both Full Bipole3 and Bipole3-Basic and is explained in the attached document.