Editing Wafer (electronics) (section)

=== Formation ===
{{See also|Boule (crystal)}}
[[File:Czochralski Process.svg|thumb|326px|The [[Czochralski method]]]]

Wafers are formed of highly pure,<ref name="Semi">SemiSource 2006: A supplement to Semiconductor International. December 2005. Reference Section:
''How to Make a Chip.'' Adapted from Design News. Reed Electronics Group.</ref>
nearly defect-free single [[crystalline]] material, with a purity of 99.9999999% ([[Nine (purity)|9N]]) or higher.<ref name="Semi" />
One process for forming crystalline wafers is known as the [[Czochralski method]], invented by Polish chemist [[Jan Czochralski]]. In this process, a cylindrical [[ingot]] of high purity monocrystalline semiconductor, such as silicon or [[germanium]], called a [[Boule (crystal)|boule]], is formed by pulling a [[seed crystal]] from a [[melt (manufacturing)|melt]].<ref>{{cite book |title=Microelectronic Materials and Processes |last=Levy |first=Roland Albert |year=1989 |pages=1–2 |publisher=Springer |isbn=978-0-7923-0154-7 |url=https://books.google.com/books?id=wZPRPU6ne7UC&pg=PA248 |access-date=2008-02-23}}</ref><ref name=Grover/> Donor impurity atoms, such as [[boron]] or [[phosphorus]] in the case of silicon, can be added to the molten [[Intrinsic semiconductor|intrinsic material]] in precise amounts in order to [[Doping (semiconductor)|dope]] the crystal, thus changing it into an [[extrinsic semiconductor]] of [[N-type semiconductor|n-type]] or [[P-type semiconductor|p-type]].

The boule is then [[wikt:sliced|sliced]] with a wafer saw (a type of [[wire saw]]), machined to improve flatness, chemically etched to remove crystal damage from machining steps and finally [[polishing|polished]] to form wafers.<ref>{{cite book |last=Nishi |first=Yoshio |year=2000|title=Handbook of Semiconductor Manufacturing Technology |pages=67–71 |publisher=CRC Press |isbn=978-0-8247-8783-7 |url=https://books.google.com/books?id=Qi98H-iTgLEC&q=wafer+flat+and+notch&pg=PA70 |access-date=2008-02-25}}</ref> The size of wafers for photovoltaics is 100–200&nbsp;mm square and the thickness is 100–500&nbsp;μm.<ref>{{cite web |url=https://www.pveducation.org/pvcdrom/design-of-silicon-cells/silicon-solar-cell-parameters |title=Silicon Solar Cell Parameters |access-date=2019-06-27}}</ref> Electronics use wafer sizes from 100 to 450&nbsp;mm diameter. The largest wafers made have a diameter of 450&nbsp;mm,<ref>{{cite web|url = http://www.f450c.org/infographic/|archive-url = https://archive.today/20160105165200/http://www.f450c.org/infographic/|url-status = usurped|archive-date = January 5, 2016|title = Evolution of the Silicon Wafer|website = F450C}}</ref> but are not yet in general use.