Creating Computer Chips

Integrated Circuits

What is an IC?

In the 1950s computers were built with vacuum tubes

A vacuum tube is• A single switch• Produced a lot of heat• Used a lot of power• Burned out frequently

What is an IC?

By the mid 1950s vacuum tubes were replaced by transistors.

A transistor • is a single switch• uses low power• gives off little heat• is reliable

What is an IC?

In 1959 two engineers independently invented ways to put transistorized switches onto a wafer of silicon.

Jack Kilby, working at

Texas Instruments,

Robert Noyce at Fairchild

Semiconductor

What is an IC?

An Integrated Circuit is• hundreds to thousands of

switches (transistors)on a single silicon chip

• low power

• inexpensive

• reliable

More powerful computers are possible with ICs

How are ICs Made?

Design• It takes a team of up to 600 engineers. • The engineers face a task equivalent to trying to

design a small city from the ground up.

How are ICs Made?

Manufacture• Computer chips begin as a material called

silicon.• Silicon is an element like oxygen or carbon

How are ICs Made?

Manufacture• The silicon is crafted into thin, large

"wafer-like" sheets. (wafers)

• The transistors and other components are applied in layers

How are ICs Made?

Manufacture• A single wafer may contain hundreds or

even thousands of individual ICs

• Each IC is removed from the wafer and placed in a package that we know as a computer chip

Creating ICs—Vocabulary

Bunny Suit Mask

Clean Room Micron

Contamination Photoresist

Etching Quality Control

Fab Semiconductor

Fabrication Wafer

Bunny Suit

• Special clothing worn by workers in a clean room that helps to keep human contaminants away from the chips.

Clean Room

• The area of the fabrication plant where the chips are made that is kept extremely clean of dust, dirt and other contamination.

Contamination

• Intrusion or contact with dirt, dust or impurities that adversely affect chip fabrication.

Etching

• The process of immersing the wafer in a chemical bath—usually an acid or solvent—that removes the photoresist that was exposed to light.

Fab

• The fabrication plant that houses the entire business of manufacturing computer chips.

Fabrication

• The process of manufacturing computer chips.

Mask

• A patterned plate or template used to expose selected areas of a wafer to light in the process of fabrication a computer chip.

Micron

A unit of measure that is one millionth of a meter; synonymous with micrometer.

Photoresist

• A light-sensitive material that changes chemically when light shines on to it.

Quality Control

• The stage of testing chips for defects. The smallest mistake, such as a slight misalignment of the mask, can destroy some or all of the chips on a wafer.

Micron

• A unit of measure that is one millionth of a meter; synonymous with micrometer.

Semiconductor

• A substance, like silicon, with electrical conductivity between that of an insulator and a conductor: Most electronic circuits are made with semiconductor components.

Wafer

• A very thin slice of very pure silicon crystal (99.9999% pure)