Editing Semiconductor device fabrication (section)

==Prevention of contamination and defects==
{{Main|Cleanroom}}
When feature widths were far greater than about 10 [[micrometre]]s, semiconductor purity was not as big of an issue as it is today in device manufacturing. In the 1960s, workers could work on semiconductor devices in street clothing.<ref>{{Cite web|url=https://www.computerhistory.org/revolution/digital-logic/12/288|title=From a Slice of Crystal to an IC Wafer - CHM Revolution|website=www.computerhistory.org}}</ref> As devices become more integrated, [[cleanroom]]s must become even cleaner.  Today, fabrication plants are [[Pressurization|pressurized]] with filtered air to remove even the smallest particles, which could come to rest on the wafers and contribute to defects. The ceilings of semiconductor cleanrooms have [[fan filter unit]]s (FFUs) at regular intervals to constantly replace and filter the air in the cleanroom; semiconductor capital equipment may also have  their own FFUs to clean air in the equipment's EFEM which allows the equipment to receive wafers in FOUPs. The FFUs, combined with raised floors with grills, help ensure a laminar air flow, to ensure that particles are immediately brought down to the floor and do not stay suspended in the air due to turbulence. The workers in a semiconductor fabrication facility are required to wear [[cleanroom suit]]s to protect the devices from [[contamination]] by humans.<ref name=humanParticleShedding /> To increase yield, FOUPs and semiconductor capital equipment may have a mini environment with ISO class 1 level of dust, and FOUPs can have an even cleaner micro environment.<ref name="auto5"/><ref name="auto6"/> [[FOUP]]s and [[SMIF (interface)|SMIF]] pods isolate the wafers from the air in the cleanroom, increasing yield because they reduce the number of defects caused by dust particles. Also, fabs have as few people as possible in the cleanroom to make maintaining the cleanroom environment easier, since people, even when wearing cleanroom suits, shed large amounts of particles, especially when walking.<ref>{{Cite web|url=https://www.chiphistory.org/159-asyst-smif-system|title=The ASYST SMIF system - Integrated with the Tencor Surfscan 7200|website=Chip History|access-date=2020-10-14|archive-date=2020-10-16|archive-url=https://web.archive.org/web/20201016072725/https://www.chiphistory.org/159-asyst-smif-system|url-status=live}}</ref><ref name=humanParticleShedding >{{Cite web|url=https://www.cleanroomtechnology.com/news/article_page/Study_into_human_particle_shedding/62768|title=Study into human particle shedding|website=www.cleanroomtechnology.com|access-date=2020-10-14|archive-date=2020-10-15|archive-url=https://web.archive.org/web/20201015035227/https://www.cleanroomtechnology.com/news/article_page/Study_into_human_particle_shedding/62768|url-status=live}}</ref><ref name=globalFoundries >{{Cite web|url=https://www.pcmag.com/news/how-a-chip-gets-made-visiting-globalfoundries|title=How a Chip Gets Made: Visiting GlobalFoundries|first=Michael J.|last=Miller|date=February 15, 2018|website=PCMag Asia|access-date=November 23, 2023}}</ref>