Editing Ion implantation (section)

=== Ion source ===
All varieties of ion implantation beamline designs contain general groups of functional components (see image). The first major segment of an ion beamline includes an ion source used to generate the ion species. The source is closely coupled to biased electrodes for extraction of the ions into the beamline and most often to some means of selecting a particular ion species for transport into the main accelerator section.

The ion source is often made of materials with a high melting point such as tungsten, tungsten doped with lanthanum oxide (lanthanated tungsten), molybdenum and tantalum. Lanthanum oxide helps extend the life of the ion source.<ref>https://www.axcelis.com/wp-content/uploads/2019/02/Hsieh_IIT2016.pdf</ref> Often, inside the ion source a plasma is created between two tungsten electrodes, called reflectors, using a gas often based on fluorine or hydrogen containing the ion to be implanted whether it is [[germanium]], [[boron]], or [[silicon]], such as boron trifluoride,<ref>{{cite book | url=https://books.google.com/books?id=vqUSBwAAQBAJ&dq=bf3+ion+implantation&pg=PA76 | title=Ion Implantation: Basics to Device Fabrication | isbn=978-1-4615-2259-1 | last1=Rimini | first1=Emanuele | date=27 November 2013 | publisher=Springer }}</ref> boron difluoride,<ref>{{cite book |doi=10.1109/IIT.2014.6940042 |chapter=Improved ion source stability using H<sub>2</sub> co-gas for fluoride based dopants |title=2014 20th International Conference on Ion Implantation Technology (IIT) |date=2014 |last1=Hsieh |first1=Tseh-Jen |last2=Colvin |first2=Neil |pages=1–4 |isbn=978-1-4799-5212-0 }}</ref>  germanium tetrafluoride or silicon tetrafluoride.<ref name="semiconductor-digest.com">{{cite web | url=https://www.semiconductor-digest.com/source-materials-enable-the-evolution-of-the-ion-implantation-process/ | title=Source Materials Enable the Evolution of the Ion-Implantation Process | date=8 February 2020 }}</ref> [[Arsine|Arsine gas]] or [[phosphine gas]] can be used in the ion source to provide arsenic or phosphorus respectively for implantation.<ref>{{cite book | url=https://books.google.com/books?id=nDhpLa1rl44C&dq=arsine+ion+implantation&pg=RA3-SA83-PA10 | title=Encyclopaedia of Occupational Health and Safety | isbn=978-92-2-109816-4 | last1=Stellman | first1=Jeanne Mager | date=28 February 1998 | publisher=International Labour Organization }}</ref> The ion source also has an indirectly heated cathode. Alternatively this heated cathode can be used as one of the reflectors, eliminating the need for a dedicated one,<ref name="auto4">{{cite book | url=https://books.google.com/books?id=PsVVKz_hjBgC&dq=ion+source+repeller&pg=SA7-PA43 | isbn=978-1-4200-1766-3 | title=Handbook of Semiconductor Manufacturing Technology | date=19 December 2017 | publisher=CRC Press }}</ref><ref>{{cite journal |last1=Horsky |first1=Thomas N. |title=Indirectly heated cathode arc discharge source for ion implantation of semiconductors |journal=Review of Scientific Instruments |date=April 1998 |volume=69 |issue=4 |pages=1688–1690 |doi=10.1063/1.1148866 |bibcode=1998RScI...69.1688H }}</ref><ref name="auto2">{{cite web|url=https://global-sei.com/technology/tr/bn73/pdf/73-03.pdf|title=History of Ion Implanter and Its Future Perspective|website=global-sei.com|first1=Masayasu|first2=Masao|last1=Tanjyo|last2=Naito|archive-url=https://web.archive.org/web/20241201191443/https://global-sei.com/technology/tr/bn73/pdf/73-03.pdf|archive-date=1 December 2024|url-status=live}}</ref> or a directly heated cathode is used.<ref>{{cite journal |last1=Sakai |first1=Shigeki |last2=Hamamoto |first2=Nariaki |last3=Inouchi |first3=Yutaka |last4=Umisedo |first4=Sei |last5=Miyamoto |first5=Naoki |title=Ion sources for ion implantation technology (invited) |journal=Review of Scientific Instruments |date=February 2014 |volume=85 |issue=2 |pages=02C313 |doi=10.1063/1.4852315 |pmid=24593650 |bibcode=2014RScI...85bC313S }}</ref>

Oxygen-based gases (oxides) can be used to provide ions for implantation such as carbon dioxide for implanting [[carbon]]. Hydrogen or hydrogen with xenon, krypton or argon may be added to the plasma to delay the degradation of tungsten components due to the halogen cycle.<ref name="semiconductor-digest.com"/><ref name="auto2"/><ref>{{cite book |doi=10.1109/IIT.2016.7882870 |chapter=Exemplary Ion Source for the Implanting of Halogen and Oxygen Based Dopant Gases |title=2016 21st International Conference on Ion Implantation Technology (IIT) |date=2016 |last1=Hsieh |first1=Tseh-Jen |last2=Colvin |first2=Neil K. |pages=1–4 |isbn=978-1-5090-2024-9 }}</ref><ref>{{cite book |doi=10.1109/IIT.2014.6940042 |chapter=Improved ion source stability using H<sub>2</sub> co-gas for fluoride based dopants |title=2014 20th International Conference on Ion Implantation Technology (IIT) |date=2014 |last1=Hsieh |first1=Tseh-Jen |last2=Colvin |first2=Neil |pages=1–4 |isbn=978-1-4799-5212-0 }}</ref> The hydrogen can come from a high pressure cylinder or from a hydrogen generator that uses electrolysis.<ref name="auto3">{{cite web|url=https://www.axcelis.com/wp-content/uploads/2019/03/Production-Worthy-Al-beams-for-SiC-Applications.pdf|title=Production-worthy Al beams for SiC applications|website=www.axcelis.com|archive-url=https://web.archive.org/web/20240218233026/https://www.axcelis.com/wp-content/uploads/2019/03/Production-Worthy-Al-beams-for-SiC-Applications.pdf|archive-date=18 February 2024|url-status=live}}</ref> 
Repellers at each end of the ion source continually move the atoms from one end of the ion source to the other, resembling two mirrors pointed at each other constantly reflecting light.<ref name="auto4"/>

The ions are extracted from the source by an extraction electrode outside the ion source through a slit shaped aperture in the source,<ref>{{cite web|url=https://www.semitracks.com/newsletters/march/2012-march-newsletter.pdf|title=Ion Implanation Part 1 - Equipment|website=www.semitracks.com|publisher=Semitracks|first=Christopher|last=Henderson|archive-url=https://web.archive.org/web/20240218233025/https://www.semitracks.com/newsletters/march/2012-march-newsletter.pdf|archive-date=18 February 2024|url-status=live}}</ref><ref>{{cite book |doi=10.1109/PAC.1991.164876 |chapter=Ion sources for commercial ion implanter applications |title=Conference Record of the 1991 IEEE Particle Accelerator Conference |date=1991 |last1=Walther |first1=S.R. |last2=Pedersen |first2=B.O. |last3=McKenna |first3=C.M. |pages=2088–2092 |isbn=0-7803-0135-8 }}</ref> then the ion beam then passes through an analysis magnet to select the ions that will be implanted and then passes through one or two<ref>{{cite journal |last1=Satoh |first1=Shu |last2=Platow |first2=Wilhelm |last3=Kondratenko |first3=Serguei |last4=Rubin |first4=Leonard |last5=Mayfield |first5=Patrick |last6=Lessard |first6=Ron |last7=Bonacorsi |first7=Genise |last8=Jen |first8=Causon |last9=Whalen |first9=Paul |last10=Newman |first10=Russ |title=Purion XEmax, Axcelis ultra-high energy implanter with Boost™ technology |journal=MRS Advances |date=10 January 2023 |volume=7 |issue=36 |pages=1490–1494 |doi=10.1557/s43580-022-00442-9 }}</ref> linear accelerators (linacs)<ref name="auto">{{cite book |doi=10.1109/IIT.2018.8807986 |chapter=Review of Major Innovations in Beam Line Design |title=2018 22nd International Conference on Ion Implantation Technology (IIT) |date=2018 |last1=Glavish |first1=Hilton |last2=Farley |first2=Marvin |pages=9–18 |isbn=978-1-5386-6828-3 }}</ref> that accelerate the ions before they reach the wafer in a process chamber.<ref name="auto"/> In medium current ion implanters there is also a neutral ion trap before the process chamber to remove neutral ions from the ion beam.<ref>{{cite book | url=https://books.google.com/books?id=OfJuCh5hCcEC&dq=ion+implanter+neutral+beam+trap&pg=PA57 | isbn=978-0-471-79027-3 | title=Fundamentals of Semiconductor Manufacturing and Process Control | date=26 May 2006 | publisher=John Wiley & Sons }}</ref>

Some dopants such as aluminum, are often not provided to the ion source as a gas but as a solid compound  based on Chlorine or Iodine that is vaporized in a nearby crucible such as [[Aluminium iodide]] or [[Aluminium chloride]] or as a solid sputtering target inside the ion source made of [[Aluminium oxide]] or [[Aluminium nitride]].<ref name="auto3"/> Implanting antimony often requires the use of a vaporizer attached to the ion source, in which antimony trifluoride, antimony trioxide, or solid antimony are vaporized in a crucible and a carrier gas is used to route the vapors to an adjacent ion source, although it can also be implanted from a gas containing fluorine such as antimony hexafluoride or vaporized from liquid antimony pentafluoride.<ref name="semiconductor-digest.com"/> Gallium, Selenium and Indium are often implanted from solid sources such as selenium dioxide for selenium although it can also be implanted from hydrogen selenide. Crucibles often last 60–100 hours and prevent ion implanters from changing recipes or process parameters in less than 20–30 minutes. Ion sources can often last 300 hours.<ref>{{cite book |doi=10.1109/IIT.2014.6940042 | chapter=Improved ion source stability using H<sub>2</sub> co-gas for fluoride based dopants | title=2014 20th International Conference on Ion Implantation Technology (IIT) | date=2014 | last1=Hsieh | first1=Tseh-Jen | last2=Colvin | first2=Neil | pages=1–4 | isbn=978-1-4799-5212-0 }}</ref><ref name="semiconductor-digest.com"/>

The "mass" selection (just like in [[Mass spectrometry|mass spectrometer]]) is often accompanied by passage of the extracted ion beam through a magnetic field region with an exit path restricted by blocking apertures, or "slits", that allow only ions with a specific value of the product of mass and velocity/charge to continue down the beamline. If the target surface is larger than the ion beam diameter and a uniform distribution of implanted dose is desired over the target surface, then some combination of beam scanning and wafer motion is used. Finally, the implanted surface is coupled with some method for collecting the accumulated charge of the implanted ions so that the delivered dose can be measured in a continuous fashion and the implant process stopped at the desired dose level.<ref>{{cite book | first1=Robert W. | last1=Hamm | first2=Marianne E. | last2=Hamm | title=Industrial Accelerators and Their Applications | publisher=World Scientific | year=2012 | isbn=978-981-4307-04-8}}</ref>