{{Short description|Crystal growth technology}} [[File:Physical vapor transport crucible-en.svg|thumb|A diagram of the modified Lely method, showing a graphite crucible surrounded by induction coils for heating. Silicon carbide {{em|charge}} is sublimated from the bottom of the chamber and deposited on the upper lid, which is cooler.]] {{Crystallization}}

The '''Lely method''', also known as the '''Lely process''' or '''Lely technique''', is a [[crystal growth]] technology based on [[physical vapor deposition]], used for producing [[silicon carbide]] crystals for the [[semiconductor industry]].

The patent for this method was filed in the Netherlands in 1954 and in the United States in 1955 by Jan Anthony Lely of [[Philips Electronics]].<ref>{{cite patent |inventor1-last=Lely |inventor1-first=Jan Anthony |pubdate=1958-09-30 |title=Sublimation process for manufacturing silicon carbide crystals |country=US |number=2854364 |assign1=[[Philips#World_War_II|North American Philips Co., Inc.]]}}</ref> The patent was subsequently granted on 30&nbsp;September 1958, then was refined by D.&nbsp;R. Hamilton et al. in 1960, and by V.&nbsp;P. Novikov and V.&nbsp;I. Ionov in 1968.{{r|Byrappa}}

==Overview== The Lely method produces bulk silicon carbide crystals through the process of [[Sublimation (phase transition)|sublimation]]. Compared to the [[Czochralski method]] which produces [[Single crystal|single crystals]] from a molten liquid, sublimation is required for SiC since it does not melt but rather decomposes into gas form at high temperatures.<ref name="e884">{{cite book | last=Chen | first=Wai-Kai | title=The VLSI Handbook | publisher=CRC Press | date=2018-10-03 | isbn=978-1-4200-0596-7 | page=}}</ref>

Silicon carbide powder is loaded into a graphite [[crucible]], which is purged with [[argon]] gas and heated to approximately {{cvt|2500|C|F}}. The silicon carbide near the outer walls of the crucible sublimes and is [[Deposition (phase transition)|deposited]] on a graphite rod near the center of the crucible, which is at a lower temperature.<ref name="Byrappa">{{cite book |last1=Byrappa |first1=Kullaiah |last2=Ohachi|first2=Tadashi |title=Crystal Growth Technology |date=2003 |publisher=Springer Science & Business Media |isbn=9783540003670 |url=https://books.google.com/books?id=win7M66SjYIC |accessdate=10 September 2018 |language=en}}</ref>

Several modified versions of the Lely process exist, most commonly the silicon carbide is heated from the bottom end rather than the walls of the crucible, and deposited on the lid. Other modifications include varying the temperature, [[temperature gradient]], argon pressure, and geometry of the system. Typically, an [[induction furnace]] is used to achieve the required temperatures of {{cvt|1800|-|2600|C|F}}.{{r|Byrappa|p=195}}

==See also== *[[Acheson process]] *[[Czochralski method]] *[[Sublimation sandwich method]]

==References== {{reflist}}

[[Category:Crystallography]] [[Category:Materials science]] [[Category:Thin film deposition]]

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