Transcript Nanoscale structures in Integrated Circuits

Nanoscale structures in
Integrated Circuits
By Edward Mulimba
Presentation Outline
 Introduction and history
 Review of current chip manufacturing
methods
 Limitations of current methods
 2 currently researched methods
 conclusion
Nanotech Definition
 Creation and use of materials, systems or
components involving measurements
between 1 and 100 nm
 nanometer = one billionth of a meter (10 –9
meter )
 Herald new advances in engineering,
medicine, and computing
 Spending US ($3.7 billion) Japan ($1 billion)
and EU($3.3 billion)
What is Integrated Circuit?
 Small electronic device
made from
semiconductor
material (usually
silicon)
 Developed mainly by
Jack Kilby of Texas
Instruments
 Usually contains
transistors and other
small components
Moore’s Law
 Intel co founder Gordon Moore observed in
1965
 Number of transistors per integrated circuit
chip would double in each technology
generation
 Early generation just had 30 transistors,
today could exceed few hundred million per
chip.
Table showing transistor size trend
YEAR
1995
2000
2004
2006
2010
ITRS
ESTIMATED
SIZE (in nm)
350
180
90
70
45
Source ITRS Executive Summary 2003 Edition
Current basic chip fabrication method
LIGHT
MASK
PHOTORESIST
FILM
SUBSTRATE
Current lithography techniques
 Extreme ultraviolet (EUV) lithography



Most prominent
Backed by Intel, Motorola, and now IBM
Uses very short wavelength
Current lithography techniques (cont)
 Electron-beam lithography



Backed by Lucent Technology, Nikon
Uses electrons instead of light
Takes too long to make chip
Current lithography techniques (cont)
 Maskless lithography
 Developed jointly by
Swedish and Dutch
companies
 Uses millions of
microscopic mirrors to
direct laser light on
wafer
 Too slow and costly
Limitations of current chip fabrication
methods
 Cost of fabrication plants is exorbitant

Moore’s second law – corollary to first
“The cost of new chip fabrication plants
increases exponentially as new features
get smaller”
 Wires carved on silicon by standard
lithography methods generate too much heat
Limitations of current chip fabrication
methods (cont).
 Physical limitations for example transistors at
about 50 nanometers dimensions electrons
start obeying quantum laws
Advantages of molecular chip making
 Could be relatively easier to make
 Potentially cost less than current methods
 Molecules can be used to build items that are
few nanometers in size
 Lack imperfections that arise from etching
lines as done in lithography
IBM molecular IC
 Uses carbon nanotubes which can be grown
into smaller dimensions
 Instead of constructing good nanotubes one
by one, many are built then defective ones
are destroyed on the wafer
 Patented method referred to “constructive
destruction”
 IBM to conduct more research to see if
carbon nanotubes outperform silicon
transistors
Using germs to build circuits
 Research carried out at University of Texas
lead by A. Belcher
 Hired virus to be a nano-construction worker
 Genetically engineered viruses grab dots of
zinc sulfide to form viral semiconductors
 They are then arranged into highly ordered
structures which could be made into
nanoscale devices.
Research Progress
 The researchers have been able to form
nanometer scale semiconductor crystals
using these viruses (2-3 nm crystals)
 Application of this kind of technology would
be sensors, quantum-dot flash memories
 Goal is to tinker with viral DNA so as to create
desired semiconductor components with the
immediate target being a transistor.
Recap
 Use of current technology can extend
Moore’s Law for few years.
 New methods such as discussed in the
presentation may offer a cheaper and
effective way of extending the law in the long
term
 Challenge for computer scientists to design
systems that can fully utilize the changing
integrated circuits
References
 Fairley, P. Germs that build Circuits. IEEE
Spectrum Nov. 2003 pg 37
 Savage, N. A revolutionary Chipmaking
Technique. IEEE Spectrum Nov. 2003 pg 18
 International Technology Roadmap for
Semiconductors. Executive Summary 2003
 Rotman, D. Molecular computing. Technology
Review. May 2000 v103
 Service, R. Assembling nanocircuits from
Bottom up. Science August 2001 v293