North American ASSURE ConferencePortland, OR, May 15 - 17, 2002

Electro-thermal IC Simulation with Saber

Presented by Michael Domnitei, MSEE

Outline

Introduction Integrated circuits as electro-thermal systems Thermal and electro-thermal simulation Thermal modeling with Thermsim Simulation features of Thermsim Integration in the CAD environment Simulation example Conclusions

Saber HistoryThe Saber simulator was originally developed and marketed in 1986 by Analogy, Inc., Beaverton, Oregon.

In February 2000, Avant! Corporation acquired Analogy. In June 2002, Avant! merged with Synopsys, Inc.

Synopsys, Inc. is now the leader in high performance software and model libraries for top-down design and behavioral simulation of mixed-signal and mixed-technology systems.

Saber simulator suite of tools runs on Unix, Linux and Windows.Saber also runs in computer grid environments for distributed iterative analysis (DIA) to speed up Monte Carlo analysis. Mixed-signal and mixed-technology simulation at any combination of levels is native to Saber design tools.

What is Saber?

Saber is a suite of tools used for analog, digital and mixed-signal and mixed-technology simulations. The suite includes Saber Sketch™ for design capture, Saber Guide™ for control (simulations), and CosmosScope™ for post process analysis.Saber Sketch lets you create and edit designs, SaberGuide allows interactive simulation control, and CosmosScope allows for graphical data analysis and viewing. All of the applications are designed for graphically based interaction, although keyboard entry and a command language are available to those who prefer text-based commands and batch scripts runs for automation and customization (in production env.).

Why is Saber Unique?

Saber is a single-kernel mixed-signal simulator that uses Synopsys’ patented Calaveras™ algorithm to synchronize analog and digital signals.

Saber is also the first simulator to be based upon a true Mixed-Signal Hardware Description Language - MAST.

SaberHDL uses VHDL-AMS and/or MAST models.

MAST is a powerful mathematics-based modeling language that allows models to be described at any level of abstraction - from high-level behavioral models, to detailed level models. This makes Saber suitable for both Top-down and Bottom-up design methodologies.

Mixed-Technology Design Electrical System Design

Saber SimulatorMixed-Technology Simulation

Saber Tool Relationships

Saber SketchDesign Capture

Saber HarnessDesign Capture

CosmosScopePlotting & Measurement

InSpecsAdvancedAnalyses

3R

D P

art

y In

teg

ratio

ns

3R

D Pa

rty Inte

gra

tion

s

ModelLibraries

Saber Bundle2-D Layout

What Types of Analyses can Saber do?

• DC• DC Transfer Analysis• Time-domain (transient)• Frequency

– Small-signal AC– Noise– Distortion– Two-Port

• Linear Systems Analysis– Pole-Zero– Linear Time Response– Frequency Response

• Stress

Statistical Monte Carlo Statistical Summary Histogram

Parametric Sensitivity Vary

Fourier Fourier FFT IFFT

Fault Detection

Thermal Analysis is the simulation and extraction of the relationship between the physical behavior and/or other properties of a system and its temperature. The essence of this analysis is that the system's response is recorded as a function of temperature and time.

By investigating the electro-thermal behavior designers can:

Determine maximum temperatures in dissipating structures

Dimension dissipating structures

Better package selection

Improve reliability

Shorten time to market cycle by increasing design efficiency.

Benefits of the thermal and electro-thermal simulation during ASIC development

Benefits of the thermal and electro-thermal simulation during ASIC development

Observations Semiconductors dissipate power and in many cases it's not possible to use fans or it's not sufficient to simply add “ a bigger fan" as a downstream fix for thermal problems.

Heat flow must be planned and thermal resistances must be optimized.

Elevated temperatures are a major contributor to lower semiconductor reliability.

If heat isn't removed at a rate equal to or greater than its rate of generation, junction temperatures will rise and shorten component’s life time.

Integrated circuits as electro-thermal systems

Electro-thermal system

Thermal and electro-thermal simulation

Thermal multiport

model

Si die, package, environment

Thermal multiport

model

T1

Tn

T2

P1

P2

Pn

Thermal simulation

Thermal multiport

model

Electro-thermal netlist

P1

P2

Pn

T1

Tn

T2

Electrothermal simulation

Thermal and electro-thermal simulation

SABER

Netlist

conversion

Electical netlist

Electrothermalnetlist

Thermal Module

Generator

Thermal System Properties

Thermal Multiport MAST Model

Material Data

Principles of a fully coupled electro-thermal simulation

Thermal modeling with Thermsim

Example of a 3D thermal simulation structure

Thermal modeling with Thermsim

Thermal multiport implementation:

Finite Difference Model of chip and package (partial); solving the heat diffusion equation:

Implemented as equivalent thermal RC-networkHeat sources and monitor points on the chip surfaceOptional: temperature dependent material propertiesOptional: simple model for anisotropic thermal conductivityOptional: compact models for modelling package behaviorOptional: Boundary Condition models

(heat transfer coefficient for radiation and convection)

dt

dTczyxpTT ),,()(

Simulation features of Thermsim

Thermal simulation

Fully coupled electro-thermal simulation

Steady state analysis

Transient analysis

Simulation with Saber

Integration into the CAD environmentAdvantages of thermsim integration into a CAD flow:

User friendly Used by circuit and layout designers Shorter cycle time for design validation

Accomplished by:

Using tools from standard design flow

Automation

Graphical user interface

Integration in the CAD environment

Thermal Model generation

Visualization (2 D plots temperature distribution)

Netlist conversion (electrical electro-thermal)

Data export to post - processing tools & layout editor

Device geometry extraction from layout

Isotherm display in layout editor (ASCII files interface)

CAD environment with no thermal analysis

Chip Production

Netlist

Schematic entry tool

Saber

Layout editor

Device model lib

Spec Netlist

Thermsim integration into the CAD environment

Electrothermalnetlist

Modelinstance list

Devicegeometries

Isothermdata

Saber simulationresults

Thermal multiportmodel template

Thermalpackage library

Thermsim GUI

Chip Production

Schematic entry tool

Saber

Layout editor

Device model lib

Spec

Simulation example

Schematic Layout

Simulation example

Device temperatures

Simulation example

DMOS ID(T) behavior

Simulation example

BJT’s collector currents and their temperature difference

Temperature distribution at chip surface

Simulation results example

Simulation results exampleTemperature display in layout editor / layout change showing the BJT’s position with respect to isolines

Simulation example

BJT collector currents and Delta T after layout change

ConclusionsThermsim is fully operational

Electro-thermal integrated circuit simulation

Thermal and coupled electro-thermal simulation

DC and transient simulation

Chip level, PCB level, electro-thermal MEMS

Thermal behavior of packages included

Fully integrated into the CAD flow

Use by circuit designers

Applied in ASIC design in industry

Add-on option for Saber

thermsim - el2eltherm

template r_parallel p, m

electrical p,m

{

r_therm.1 p m = r=100, alpha=-0.005,

r_therm.2 p m = r=100, alpha=-0.005,

}

r_therm.1 1 0 = r=10, alpha=0.01,

r_parallel.2 1 0

r_parallel.3 1 2

i.1 2 0 = dc = 10m

v.1 1 0 = dc=10

Netlist conversion: electrical into electro-thermal

thermal=dependent

thermal=dependent

thermal=dependent

t

t

t

t__0

t__1

t__0

t__1 t__2

t__3 t__4

< thermsim_include.sin

thermsim.1 t__0 t__1 t__2 t__3 t__4 0

thermal_c t__0, t__1

, t__0, t__1