Wafer (electronics)
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See Wafer (cooking) for the original meaning of the word.
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Etchedwafer.jpg
Etchedwafer.jpg
An etched silicon wafer
They are made in various sizes ranging from 1 inch (25.4 mm) to 300 mm (11.8 inches), and thicknesses of the order of 0.5 mm. Generally, they are cut from a boule of semiconductor using a diamond saw, then polished on one or both faces.
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Wafer_flats_convention.JPG
Wafer_flats_convention.JPG
Flats can be used to denote doping and crystallographic orientation. Red represents material that has been removed.
Orientation is important since many of a single crystal's structural and electronic properties are highly anisotropic. For instance, wafer cleavage typically occurs only in a few well-defined directions. Scoring the wafer along cleavage planes allows it to be easily diced into individual chips ("dies") so that the billions of individual circuit elements on an average wafer can be separated into many individual circuits.
Sources
- A website with semiconductor lore. (http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_5/illustr/i5_2_4.html)
- Federal Standard 1037Cde:Wafer