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
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

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