wafer
(1) A small, thin continuous-loop magnetic tape cartridge that has been used from time to time for data storage and specialized applications.
(2) The base unit of chip making. It is a slice taken from a salami-like silicon crystal ingot up to 12" (300mm) in diameter. The larger the wafer, the more chips produced in a single production pass, which comprises a series of photomasking, etching and implantation steps. Wafers are approximately 1/30th of an inch thick; however, the actual layers of transistors that make up the active circuitry are only a few microns deep.
Wafers started out being very small from one to three inches in diameter. Then came 100mm ingots (approximately 4"), followed by 125, 150, 200 and 300mm. Various different wafer sizes are used today, depending on the type of chip being made. See chip and wafer scale integration.
 |
| The Boule Is Sliced |
|---|
| The silicon ingot, which is known as a "boule," is sliced into wafers. (Image courtesy of International Business Machines Corporation. Unauthorized use not permitted.) |
 |
| Different Sizes |
|---|
| The person at the top is holding 150mm wafers; in the middle 200mm; and 300mm at the bottom. (Images courtesy of Texas Instruments, Inc., Advanced Micro Devices, Inc. and Intel Corporation, respectively). |
 |
| Heating the Wafers |
|---|
| The red glow comes from a furnace that reaches 1000 degrees centigrade. The semiconductor wafers are baked in the oven to prepare them for the chip-making process. (Image courtesy of Intel Corporation.) |
wafer1. Christianity a thin disc of unleavened bread used in the Eucharist as celebrated by the Western Church
2. Pharmacol an envelope of rice paper enclosing a medicament
3. Electronics a large single crystal of semiconductor material, such as silicon, on which numerous integrated circuits are manufactured and then separated
