Microelectronics &

Device Fabrication

Vacuum Tube DevicesThermionic valve

Two (di)Electrodes (ode)

~1940, ENIAC was constructed at the Moore School of Electrical Engineering at the University of Pennsylvania. It consisted of 19,000 vacuum tubes, 1,500 relays, hundreds of thousands of resistors and capacitors; all told, including power supply and an air cooling system, it weighed over thirty tons and consumed 200 kilowatts of electrical power.

Vacuum Tube Devices

Electronic numeric integrator and computer (ENIAC) (1946) $ 400.000

Solid State Devices

• Transistors (BJT, FET, etc.)• Semiconductor materials can generate and

sense light OPTOELECTRONIC DEVICES• They can also sense magnetism, temperature,

pressure variety of SENSOR devices and TRANSDUCERS (energy converters) appeared on the market.

• Although semiconductor diodes and transistors are still widely used as individual components,

• 1959: Robert Noyce discovered that more than one transistor could be constructed on a single piece of semiconductor material.

• Then other components (resistors, capacitors, etc.) were added with transistors and then interconnected to form a complete circuit on a single chip or piece of semiconductor material.

Integrated Circuit (IC) or IC Chip

Smaller and thinner than a dime, this tiny silicon chip contains millions of transistors that work together

• Growth of Semiconductor• Device Fabrication– Oxidation– Patterning (lithography, deposition, etching)

• Packaging

Steps

Growth of Semiconductors

1. Growth from a melt (Czochralski Method)2. Epitaxial Growth: Chemical Vapor-Deposition, Liquid-

Phase Epitaxy, Molecular Beam Epitaxy

Growth From a Melt: Czochralski Method

Cleaning, sectioning...

Si Single Crystal Wafer

Device Fabrication Techniques

• Oxidation

Silicon

SiO2

Gas

Diffusion of oxygen

Photolithography

MicrofabricationEtching & Deposition

Simplified illustration of the process of fabrication of a CMOS inverter on p-type substrate in semiconductor microfabrication

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etch

stepSee «How do they make Silicon Wafers and

Computer Chips?» at youtube

Patterns created with subsequent layers of photoresist, elemental gas deposition, and/or etching and metal deposition.Source: wikicommons

Schematic structure of a CMOS chip, as built in the early 2000s.