1. Computer Chips: A World of Microelectronics
Zhi Chen, Ph.D.
Department of Electrical Engineering
University of Kentucky
Lexington, KY 40506

2. Outline History of Computers The Structure of a Computer
Microchips: Integrated Circuits
How to Make a Chip
Future of Microchips

3. History of Computers
1937 J. V. Atanasoff, a professor at Iowa State University, built an electronic computer (not programmable)
1943 Alan Turing built an electronic machine for the British military.
1945 J. Presper Eckert and John V. Mauchly at the University of Pennsylvania built the first general purpose programmable electronic computer, ENIAC (Electronic Numerical Integrator and Computer).

4. The first programmable electronic computer, ENIAC
It consists of 18,000 vacuum tubes, 70,000 resistors, 10,000
capacitors, and 6,000 switches. It was 100 feet long, 10 feet
high, and 3 feet deep. It consumed 140 kilowatts of power.

5. The first programmable electronic computer, ENIAC

6. Problems with Vacuum Tubes
What a vacuum tube looks like? ---- A light Bulb
It consists of a filament and several electrodes enclosed in a glass bulb.
Large size
Large Power Consumption
Unreliable: filaments always burn out

7. A New Invention in 1947: Transistor A Solid State Device
Transistors
--Solid State
Vacuum tubes
--- Light bulbs
Vacuum tube
Transistor
Compare the transistor with the vacuum tube:
100 times smaller, much less power consumption

8. An Invention in 1958: Integrated Circuits
Jack Kilby, inventor
The first integrated Circuit: Put every components
and wires on a Silicon chip --- A new concept.

9. Invention of IC: Beginning of Microelectronics
Electronic circuits are printed on Si wafer by photolithography and
patterning. Most importantly, they can be miniaturized continuously.

10. Computer architecture
CPU
Memory
I/O
System Bus
CPU: Central Process Units
I/O: Input / Output
All the above can be fabricated on a single chip.

11. Miniaturization: Leading to Revolution of Computers
Year Microprocessor Size (m) Transistors Clock speed
, MHz
, MHz
, MHz
,200, MHz
Pentium ,100, MHz
Pentium II ,500, MHz
Pentium III ,000, GHz
Pentium IV ,000, GHz

12. Microelectronics: How to Make Chips?
UV Light
Mask PR
Oxide
Silicon Wafer
Photochemical Reaction
PR: Photo Resist
Electronic circuits are printed on Si wafer by photolithography

13. Microelectronics: How to Make Chips
Soluble in a special solution PR
Oxide
Dissolve in the solution PR
Oxide
Oxide etch in a chemical solution PR
Oxide
PR: Photo Resist
Electronic circuits are printed on Si wafer by photolithography

14. Microelectronics: How to Make Chips
Dissolve in the solution PR
Oxide
Pattern being formed
Oxide
PR: Photo Resist
Patterns on the Mask have been transformed to the silicon wafer

15. Microelectronics: How to Make Chips
Very sophisticated patterns of 0.25 m can be made!

16. Microelectronics: What a transistor looks like?
A transistor with a size of 0.25 m can only be
seen using an electronic microscope!

17. Microelectronics: What is a transistor?
A Transistor in digital circuits is just like a switch
OFF
Represents 0 in Logic ON
Represents 1 in Logic
Millions of switches in a Computer is just
busy with on and off!

18. Microelectronics: What a wafer looks like?
There are about chips which are identical in one wafer
made by IBM in 1999.

19. Microelectronics: What a chip looks like?
This is the inside of one chip showing microprocessor
and memory made by IBM in 1999.

20. Microelectronics: What a wafer looks like?
The wafer can be sliced into chips: Economical importance.
If each chip sells for $200, one wafer values $10,000.

21. Microelectronics: What a packaged chip looks like?
Each chip can be packaged as shown above.

22. Microelectronics: Clean Room
Class 10 clean room in semiconductor industry:
10 particles per cubic feet in air

23. Microelectronics: Clean Room
High-tech workers are doing mask alignment

24. Microelectronics: Clean Room
High-tech workers are doing wafer processing

25. Microelectronics: Clean Room
High-tech workers are doing wafer test

26. Future of Microelectronics
Year Size Transistors Clock speed
Today 0.20m 10,000, MHz
m 40,000, GHz
m ~100,000, GHz
Beyond ???
Physical limit Need new devices and new concepts

27. Nanoelectronics: Quantum dot devices
Coulomb blockade effect: One electron entering into the dot will repel the other electrons from entering.
The dot size should be less than 5 nm to observe the room temperature Coulomb blockade effect.

28. Nanoelectronics: Molecular devices

29. Summary
The invention and development of modern electronic computers have changed the world.
Microelectronics is the driving force for the innovation of the computer technology.
Nanotechnology will be the future for improvement of computers.