Miniaturizing Computers: Evolution of Processors

1
Miniaturizing Computers Evolution of Processors
Past

• Matt Cohen
• Chris Rousset
• Abdallah Rahman

Present
2
The Processor

• A central processing unit (CPU), or sometimes
  simply processor, is the component in a digital
  computer that interprets computer program
  instructions and processes data. CPUs provide the
  fundamental digital computer trait of
  programmability, and are one of the necessary
  components found in computers of any era, along
  with primary storage and input/output facilities.
  Beginning in the mid-1970s, microprocessors of
  ever-increasing complexity and power gradually
  supplanted other designs, and today the term
  "CPU" is usually applied to some type of
  microprocessor.

3
The 65nm Processor

• The technology of today
• Benefits of the 90-65nm cross-over
• Increase in multimedia performance (video, audio,
  data streaming)
• Two new layers of hardware based security
  (protection against hackers and viruses)
• Advanced manageability for IT (remote problem
  resolution)
• Acceleration technology that improves the speed
  for network traffic (faster download and
  communication)

4
The 65nm Processor

• The 65nm technology
• 35nm gate length
• 1.2nm gate oxide
• NiSi for low resistance
• 2nd generation strained Silicon
• for enhanced performance
• These features prevent transistor leakage and
  reduce power consumption

5
The 45nm Processor

• Benefits of the 65-45nm cross-over
• Twice improvement in transistor density
• Five times reduction in source-drain leakage
  power
• 20 improvement in transistor switching speed
• 30 reduction in transistor switching power
• Ten times reduction in transistor gate oxide
  leakage for lower power requirements and
  increased battery life
• More performance for exponentially less cost

6
The 45nm Processor

• The production
• Intel is on track for 45nm production in the
  second half of 2007
• AMD and IBM expect the first 45nm products using
  immersion lithography and ultra-low-K
  interconnect dielectrics to be available in
  mid-2008

7
The Future

• Intel plans to use extreme ultra-violet
  lithography to print elements as small as 32 nm
  and beyond (expectations 2009)
• AMD and IBM will cooperate to devise techniques
  for manufacturing chips using the 32-nanometer
  and 22-nanometer processes (expectations 2009 and
  2011)
• Other options include replacing the use of
  Silicon by other materials such as Germanium
• Another development relates to the use of
  Graphene

8
The Use of Germanium

• Why replacing Silicon?
• For the past four decades the silicon industry
  has delivered a continuously improving
  performance at ever-reduced cost
• Those breakthroughs were achieved by physical
  scaling of the silicon device
• Physical limitations such as off-state leakage
  current and power density pose a potential threat
  to the performance enhancement that can obtained
  by geometrical scaling
• Strain engineering has quickly emerged as a new
  scaling vector for performance enhancement to
  extend the life of silicon
• But what will happen next?

9
The Use of Germanium

• Why using Germanium?
• As seen in class mobility is one of the most
  important characteristics for electronic
  applications
• According to the International Technology Roadmap
  for Semiconductors, even with strain engineering,
  metal gates and high-k dielectrics,
  semiconductors with higher mobility will be
  needed to continue scaling beyond the 22nm
  technology node
• III/IV compounds such as InSb, InAs or InGaAs
  have high electron mobility but same hole
  mobility as Si which is an issue for p-MOS
  devices
• Germanium is one solution

10
The Use of Germanium
Properties Si Ge GaAs
Atoms/cm3 5.02 x 1022 4.42 x 1022 4.42 x 1022
Effective mass electrons (m/m0) 0.26 0.082 0.067
Effective mass holes (m/m0) 0.69 0.28 0.57
Electron affinity (V) 4.05 4.0 4.07
Energy gap (eV) 1.12 0.67 1.42
Mobility electrons (cm2/V s) 1500 3900 8500
Mobility holes (cm2/V s) 450 1900 450
11
The Use of Germanium

• Problems with the use of Ge
• Germanium use will allow research and development
  to reach the 22nm node however
• The low bandgap (0.67eV) and low melting point
  (937C) poses challenges for device design and
  process integration
• Ge wafers offer poor mechanical strength and are
  much more expensive than Si wafers
• For n-MOS devices the presence of specific
  surface defects directly degrade the channel
  mobility and limit the current drive

12
The Use of Graphene

• Carbon nanotubes
• Metallic nanotubes display quantized ballistic
  conduction at room temperature
• conductance can be controlled by applying an
  electrostatic gate
• Have already been used to make simple transistors
  and logic gates
• Low-dimensional graphite structures
• Have almost identical properties of carbon
  nanotubes
• EX Graphene Ribbon

13
Nanotubes

• Nanotubes many limitations
• - limited consistency in size and electric
  properties
• - Difficulty integrating nanotubes into
  electronics efficiently
• - High electrical resistance at junctions
  between nanotubes and the
• wires connecting them.
• The solution Using Graphene layers or ribbons
• - Exact same properties as Carbon nanotubes with
  out
• the limitations.

14
Graphene layers

• Advantages
• The graphene layers are only 10 atoms thick
• (Miniaturization)
• High efficiencies and low power consumption
• Devices made from graphene layers can be made
  using standard micro-electric processing
  techniques
• (Mass production of graphene devices)
• Such standard lithographic methods

15
The Progress of Graphene Transistors

• Many universities have created transistors from
  graphene, approximately 80nm
• The goal is to make these transistors 10nm
• where the devices will display ballistic
  transport.

Single-electron logic A single-electron
transistor carved entirely in a graphene sheet.
The central element is a so-called quantum dot,
which allows electrons to flow one by one. The
dot is connected to wider regions that have
contact pads used to turn the transistor on and
off. Credit University of Manchester
16
Problems with Graphene

• Early Graphene resistors leaked current
• Working on single electron transistor using
  quantum dots to solve this problem.
• Quantum dots at room temperature are not stable
  enough.
• No fabrication techniques available to produce
  the 3nm quantum dots needed for the single
  electron transistor.
• This requires the manufacturer to once again rely
  on luck to produce the right sized quantum dot.
  This brings us back to square one as it is a
  similar problem with nanotubes.

17
Quantum Computers

• The future
• Qubits can similtaniously be 1 and 0 at the
  same time, compared to bits which can only be 1
  or 0.
• Quantum computer processes information using
  atoms and other tiny
• particles (Qubits), rather than transistors
• -EX electron (Spin up down), Photon
  (Polarization of light horizontal, vertical)
• Entanglement- quantum mechanical phenomenon where
  the quantum states of two or more objects or
  qubits have to be described with reference to
  each other.
• - For example, two photons can be entangled such
  that if one is horizontally polarized, the other
  is always vertically polarized
• -key to quantum computers
• -this is what gives the quantum computer its
  advantage along with being simultaneously on and
  off.
• In principle a quantum computer will be able to
  outperform a classical computer in certain tasks

18
Problems of the Quantum Computer

• Controlling the interaction between many
  qubits"The issue isn't how many qubits, it's how
  many well-controlled qubits," Steane says
• Detecting what stat the qubits are in

19
Sources

• http//www.nature.com
• http//physicsweb.org/articles/news/8/6/18
• http//gtresearchnews.gatech.edu/newsrelease/graph
  ene.htm
• http//www.technologyreview.com/Infotech/18264/pag
  e1/
• http//www.physics.gatech.edu/npeg/npeg.html
• http//en.wikipedia.org/wiki/Moore's_law
• http//www.eetimes.com/news/semi/showArticle.jhtml
  ?articleID196901271
• http//www.amd.com/us-en/Processors/ProductInforma
  tion/0,,30_118_9485_130415E14633,00.html
• http//www.intel.com/technology/silicon/65nm-cross
  -over.htm