TEACHING CMOS CIRCUIT DESIGN IN NANOSCALE
TECHNOLOGIES USING MICROWIND
Etienne Sicard
Sonia Ben Dhia
Department of Electrical & Computer
Engineering
INSA – University of Toulouse
France
e-mail:
etienne.sicard@insa-toulouse.fr
sonia.bendhia@insa-toulouse.fr
Syed Mahfuzul Aziz
School of Electrical &
Information Engineering
University of South Australia
Australia
e-mail:
mahfuz.aziz@unisa.edu.au
1
SUMMARY
1. CONTEXT
2. EDUCATIONAL NEEDS
3. MICROWIND
4. EVALUATION
5. PRESPECTIVES
7. CONCLUSION
2
CONTEXT
NANO-CMOS – MORE AND MORE COMPLEX
2000
0.18 µm
2005
90 nm
2010
32 nm
Devices
3 nMOS, 3 pMOS
6 nMOS, 6 pMOS
2V
1V
12 nMOS, 12 pMOS
Interconnects
Frequency
500 MHz
1V
1.5 GHz
5 GHz
3
CONTEXT
NANO-CMOS – TEACHING CHALLENGE
Low K
Drain current (A/µm)
Ion current
increase
Poly - SiO2
Double
patterning
10-3
10-4
« Ideal
device »
10-5
nMOS Strain
Metal gate
High K oxide
Pocket
implant
pMOS Strain
High-
10-6
10-7
Ioff current
decrease
10-8
10-9
10-10
0.0
0.5
1.0
Gate voltage (V)
The quest for the
« perfect switch »
4
CONTEXT
NANO-CMOS – TEACHING CHALLENGE
Ioff (nA/µm)
Parasitic
consumption
Networking
High
- end
servers1000
Computing
Servers
High (x 10)
Consumer
Mobile
Computing
Moderate
(x 1)
Digital camera 3G phone
s
Low
(x 0.1)
MP3
100
High
speed
General
Purpose
2G phones
« Super low
leakage »
10
« Super
high
speed »
Personal org.
Low leakage
1
Low
(-50%)
Moderate
(0%)
Speed
Fast
(+50%)
500
1000
1500
Ion (µA/µm)
5
CONTEXT
NANO-CMOS – COMPLEXITY CHALLENGE
Teaching cell design – still necessary ?
Complexity
(Millions transistors)
Technology
always ahead
RF
RS
1000
Host
Interface
System design
IP design
100
Code
ManagerLink
Controller
Logic design
10
1
Layout design
0.1
1995
1998
2001
2004
2007
2010
2013
Microwind
6
EDUCATIONAL NEEDS
TEACHING NANO-CMOS – TRENDS
The commercial chip design tools
available today are very powerful
However, these tools are highly complex
and need long time to learn.
Teaching hours in Nano-CMOS are
decreased
Physics of semiconductors are
exploding in complexity (100-1000
parameters in MOS models)
Student and engineer diversity must be
considered. Gaps in the background
knowledge must be addressed
Teaching
hours
Physics
CMOS design
Embedded
software
System
integration
Years
7
EDUCATIONAL NEEDS
TEACHING NANO-CMOS – NEEDS
Tools should be used by large number
of students at undergraduate level
Design tools should provide intuitive
design, simulation and visualization
environments
Reduced number of
students
Educational
tools
Ambitious designs
Graduates
Design tools should be easily
accessible. Most of the work is done out
of regular teaching hours (e-learning,
project-based..)
Target course and practical training
duration: 15 H
Long practical
sessions
:
PhDs
Professional
tools
Short
sessions
:
Simple design
Concepts
Undergraduates
Large number of students
Learning curve
Educationoriented tools
Rapid
progress
Industryoriented
tools
Slow
progress
5
10
15
Hours
20
8
MICROWIND
COURSE CONTENTS (1-2 days)
Equivalent Gate
Dielectric Thickness
(nm)
Technology scale down, where we come from,
where we are (45 nm), where we go..
10nm
High voltage
MOS (double
gate oxide)
0.25m
0.18m
0.13m
90nm
A tutorial on MOS devices, based on problembased learning
Technology
addressed in
2010
65nm 45nm
1nm
Low voltage
MOS (minimum
gate oxide)
32nm
22nm 18nm
11nm
HighK (r=7-20)
SiON (r=4.2-6.5)
0.1nm
The design of inverters, and a simple ring
oscillator, and a small student contest.
SiO2 (r=3.9)
1995
2000
Year
2005
2010
2015
The design of basic logic gates introducing
interconnect design, compact design strategies,
and impact on switching speed and power
consumption.
The design of analog blocs introducing
amplification, voltage reference, addition of analog
signals, and mixed-signal blocs
A design project, e.g. converter, processing unit,
OpAmp, radio-frequency block, etc..
9
MICROWIND
INTRODUCTION THE TOOL
User-friendly and intuitive
design tool for educational use.
The student draws the masks of
the circuit layout and performs
analog simulation
Editing icons
Layout
library
2D, 3D views
One dot on the
grid is 5
lambda, or
0.175 µm
Access to
simulation
Simulation
properties
The tool displays the layout in
2D, static 3D and animated 3D
Editing window
Palette of layers
Active technology
Ion current
List of model
parameters
for BSIM4
Threshold voltage effect
Voltage
cursors
Memory effect due to
source capacitance
10
MICROWIND
1.
MOS DEVICE
2.
Traditional teaching : in-depth
explanation of the
potentials, fields, threshold
voltage, and eventually the
expression of the current
Ids
Our approach : step-by-step
illustration of the most
important relationships
between layout and
performance.
1.
Design of the MOS
2.
I/V Simulation
3.
2D view
4.
Time domain analysis
4.
3.
11
MICROWIND
BASIC GATE DESIGN
Illustration of the most important
relationships between layout
and performance.
1.
Design of pMOS
2.
Design of inverters
3.
Design of a VCO
4.
Try to optimize the VCO for
highest possible speed
5.
Improve MOS size
6.
Change MOS options
7.
Make the layout more
compact
8.
Keep an eye on power
consumption
2.
1.
3.
4.
12
MICROWIND
PROJECT EXAMPLES
engage students in a stimulating
learning experience using
latest CMOS technologies
1.
Circuit analysis and
optimization using WinSpice
2.
Combinational and
sequential circuit layouts
3.
ALU Design
4.
Power amplifier Bluetooth
1.
3.
2.
4.
13
EVALUATION
AUDIENCE
• The VLSI course was evaluated
anonymously by the students
• UNISA course evaluation
questionnaire containing ten core
questions and open text
response.
• The students rated the course
very highly in all the evaluation
items.
• The course in the in the top-5
courses offered in engineering in
UniSA.
• (off-line: Dr. Aziz won the “top
teacher of the year” in Australia
2009)
#
Question
1
I have a clear idea of what is expected of me in this
course.
2
The ways in which I was taught provided me with
opportunities to pursue my own learning.
3
The course enabled me to develop and/or strengthen a
number of the qualities of a [University of South
Australia,INSA] graduate.
4
I felt there was a genuine interest in my learning needs
and progress.
5
The course developed my understanding of concepts and
principles
6
The workload for this course was reasonable given my
other study commitments
7
I have received feedback that is constructive and helpful.
8
The assessment tasks were related to the qualities of a
[University of South Australia, INSA] graduate.
9
The staff teaching in this course showed a genuine
interest in their teaching.
10 Overall I was satisfied with the quality of this course
14
EVALUATION
RESULTS
Answers to questionnaire
INSA
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
% response
% response
UNISA
1
2
3
4
5
6
7
8
9
10
80%
70%
60%
50%
40%
30%
20%
10%
0%
1
2
3
Evaluation item #
Strongly agree
Agree
Neutral
Disagree
4
5
6
7
8
9
Evaluation item #
Strongly disagree
Strongly agree
Agree
Neutral
Disagree
Strongly disagree
5. The course developed
my understanding of
concepts and principles
15
10
EVALUATION
COMMENTS
Students
“From just a few logic gates, we have created
a 4-stage binary counter and compiled it into
layout. It also gave us the basic concepts to
understand the operation of the transistors in
order to extract their models.”
“The 24-hours clock project was a good
exercise which permitted us to see how it is
inside a semiconductor and how it works.”
“We learned a lot about designing integrated
circuit. We faced some practical problems,
and tried to solve them or to understand
them.”
“This study allows us to understand the DAC
running. In spite of some design problems,
we managed to make the DAC work well.”
“Before doing this project, we hadn’t thought
that there are as many ways to realize an
amplifier. It’s an area not easy to understand.
Each technique has its limit. We tried to
optimize our operational amplifier design to
maximize the gain.”
Teachers
“The tools along with the project-based
course resources have assisted us to
develop an educational program in our
Bachelor of Engineering Program. The tools
offer easy to use menus for design and
simulation, and the choice of a range of
technology models to enable students to
develop critical design and analysis skills
using the latest technologies.” (Malaysia).
“Microwind and Dsch tools are used for VLSI
teaching programs at both postgraduate and
undergraduate levels. The project-based
methodology supported by a variety of
learning resources has made the learning
of VLSI Design very stimulating.”
(Bangladesh).
“Exploring the tools is a lot of fun. The
interface is very friendly, and the program is
both educational and useful for designing
CMOS chips.” (USA)
16
PERSPECTIVES
•
Application note on 32 nm
& 22 nm technologies
•
Application note on
process variability and
Monte-Carlo simulation
•
3D views of packages
based on IBIS
•
3D views of carbon-nano
tubes
17
CONCLUSION

Intuitive and user friendly design tools enabled students to develop circuit
design skills using nano-CMOS technologies

Illustrations (2D, 3D, I/V) help to handle increased process complexity and
refinements

Effective project-based learning methodologies, helping to understand the
impacts of technology scale down on factors such as speed, power and
noise.

Digital and analog basic bloc design with high levels of student satisfaction.

Projects stimulate student curiosity and thinking.

Software to be tuned to 22, 17 and 11 nm technologies

Novel devices to be introduced when appropriate
18
REFERENCES
[1] E. Sicard and S. Ben Dhia “Basic CMOS Cell
Design” McGraw Hill professional series, 2006.
[2] E. Sicard and S. Ben Dhia “Advanced CMOS
Cell Design” McGraw-Hill professional series, 2007.
[3] E. Sicard, “Microwind & Dsch User's Manual,
Version 3.5”, June 2009. Online at
www.microwind.org.
[4] S. M. Aziz, E. Sicard, S. Ben Dhia “Effective
Teaching in Physical Design of Integrated Circuits
using Educational Tools” to appear IEEE Trans
Education, 2010
The tool, manual and course
slides are online at
www.microwind.org
19
REFERENCES
MICROWIND DOWNLOADS – www.microwind.net
20
THANK YOU FOR YOUR ATTENTION
21