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

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

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).

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.

The first programmable electronic computer, ENIAC

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

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

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.

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

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.

Miniaturization: Leading to Revolution of Computers Year Microprocessor Size (m) Transistors Clock speed 1974 8080 6 6,000 2 MHz 1979 8088 3 29,000 5 MHz 1985 80386 1.5 275,000 16MHz 1989 80486 1 1,200,000 25MHz 1993 Pentium 0.8 3,100,000 60MHz 1997 Pentium II 0.35 7,500,000 233MHz 2000 Pentium III 0.18 15,000,000 1.0 GHz 2003 Pentium IV 0.09 30,000,000 2.0 GHz

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

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

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

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

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

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!

Microelectronics: What a wafer looks like? There are about 50-60 chips which are identical in one wafer made by IBM in 1999.

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

Microelectronics: What a wafer looks like? The wafer can be sliced into 50-60 chips: Economical importance. If each chip sells for $200, one wafer values $10,000.

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

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

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

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

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

Future of Microelectronics Year Size Transistors Clock speed Today 0.20m 10,000,000 700MHz 2010 0.07m 40,000,000 4 GHz 2015 0.05 m ~100,000,000 16 GHz Beyond 2015 ??? Physical limit ------Need new devices and new concepts

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.

Nanoelectronics: Molecular devices

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.