To learn more please visit the link below:
Complying with EPA New Source Requirements(NSR) make Investing in new wafer fabs or expanding existing sites more costly and complicated.
As the following link makes clear plant expansions in non-attainment areas are even more complicated.
To quote from the document:
The terms “RACT,” “BACT,” and “LAER” are acronyms for different program requirements under the NSR program.
RACT, or Reasonably Available Control Technology, is required on existing sources in areas that are not meeting national ambient air quality standards (i.e., non-attainment areas). BACT, or Best Available Control Technology, is required on major new or modified sources in clean areas (i.e., attainment areas).
LAER, or Lowest Achievable Emission Rate, is required on major new or modified sources in non-attainment areas.
While there are many sources of air pollutants that are emitted from wafer fabs a major pollution source is IPA soaked wipers. Cleanroom wipers either presaturated with IPA or wetted via squirt bottles are major source of VOC fugitive emissions. While some cleaning procedures can be accomplished with blends of water and IPA most require 100% IPA to produce clean dry surfaces. Depending on the size of the wafer fab, IPA wipers generate 5-30 tons of fugitive VOC emissions per year.
In order to help wafer fabs achieve a step change reduction in VOC fugitive emissions Foamtec has introduced the first cleanroom wiper pre-saturated with 100% Ultrapure water. MiraSAT®, due to its unique woven microfiber construction offers IPA like cleaning without all the VOC’s enabling tighter compliance with EPA and air quality control district air permits.
LEARN MORE ABOUT MIRASAT®
Defects in 200mm & 300mm litho modules are a common, yet costly issue.
A major source of defects in lithography modules are fibers & particulates including resist particles that have been left in the track. Contamination that migrates to the scanner or stepper can result in serious defects including difficult to remedy hot spot and defocus issues.
Above: wafer handler End-Effector with hanging lint fiber will cause scratch signature on production wafer.
Reduce Defects at the Start
Foamtec International WCC has created a cleaning BKM/SOP that enables much more thorough cleaning so that Track equipment have higher first pass QUAL rates. As a result, backside wafer contamination is greatly reduced minimizing cross contamination on scanner wafer table.
The SOP is production proven to reduce the need for and harsh wafer table polishing (stoning) PM’s, where a round abrasive stone is used to recondition the surface of the wafer table to help prevent hot spots and defocus issues. A frequent stoning procedure will reduce the lifetime of the expensive wafer table.
Above: Track oven with Foamtec ergonomic cleaning tool
Foamtec’s Track cleaning SOP helps eliminate hot spots, reduce resist and the need to stone the scanner wafer table, resulting in improved uptime greatly reducing defects and cost.
Below, the defect reduction measured with a surface particle counter is evident.
For more information on Foamtec International’s BKM/SOP that will deliver a decrease in litho hot spots, fewer defocus issues, and longer time between stoning and cleaning of the table/chuck in the scanner email us at firstname.lastname@example.org or visit our website at www.foamtecintlwcc.com
At medical device manufacturing facilities, controlling particles and fibers is a critical task as foreign material (FM) is a leading cause of reject and rework. Moreover, the inspection, cleaning and rework process are major drags on productivity.
Because FM is and always will be present, devices are most often assembled in ISO 7 and 8 clean rooms. These room classifications dictate a controlled level of contamination, but even when airborne counts are within specification, operators frequently come in contact with devices contaminated with fibers 100-500 micron in size.
Lets understand what happens at the workstation when inspection reveals that fibers are present on the device.
To begin with, the inspection process carried out by the operators and Quality Control staff is labor-intensive and by no means fool proof.
QC staff has designated three categories of FM contamination:
(1) Fully Embedded Fibers
Devices with fibers that are fully embedded in the coating or the component. These devices can either be immediately disregarded as scrap or may pass the quality requirements and manufacturing may proceed. Both conclusions are entirely based on the specific product and the FM requirements in place. Either way, it is out of the operator’s control.
(2) Loose Fibers
Loose fibers on the surface of the device may be removed with wipers, swabs or hand tools. Especially when hand tools are required this is very labor intensive and expensive process. It is not uncommon for operators to use wipers , swabs and hand tools to rework devices. Especially when hand tools are required this is very labor intensive and expensive process.
(3) Semi-Embedded Fibers
Fibers that are semi-embedded comprise the most difficult category of contamination. These are most frequently removed with tweezers and the removal process may lead to expensive scrap or rework, especially if coatings are involved.
It is easy to see that for many facilities, the steps taken to remove large fibers can significantly impact the cost of the device and the productivity of the facility. Please stay tuned for future articles that discuss root cause solutions or contact us if you would like more information to reduce contamination related defects and rework
A Major Source of VOC’s are IPA-Soaked Wipers.
Despite initiatives that target sustainability and Environmental Health and Safety (EH&S) performance improvements, companies that operate cleanrooms struggle to reduce Volatile Organic Compounds (VOC’s). Additionally, much of the VOC emissions are from spent wipers that are sitting in hazardous waste cans.
While the EH&S issues associated with Isopropyl Alcohol (IPA) are well understood, finding a suitable replacement has eluded the best efforts of cleanroom professionals. The surface tension and vapor pressure properties of IPA which make it so desirable as cleaning agent are directly tied to the EH&S risks that have so challenged cleanroom operators.
In addition to acute flammability and VOC issues, users also face health risks from long term exposure to IPA fumes.
Is it possible to Replace IPA-Soaked Wipers?
Deionized (DI) water as the universal solvent is the ideal substitute for IPA but existing polyester cleanroom wipers do not possess the absorbency or particle removal properties to enable its use. This is especially the case in microelectronics where much of the wiping is carried out on high vacuum chambers that require clean, dry surfaces to minimize pump down times.
In large part, wafer fabs and other microelectronic cleanrooms are forced to use IPA due to the poor absorption and pick-up properties of polyester cleanroom wipers.
Polyester’s circular shaped, adsorbent fiber offers very limited particle dislodgement and liquid pickup which necessitates the use of IPA to achieve clean, dry surfaces.
VOC Free Wiping.
To enable microelectronic manufacturing facilities to replace IPA with DI water, Foamtec has developed MiraWIPE® Wipers, a unique microfiber fabric designed to produce ultra clean and dry surfaces. MiraWIPE® is already production proven to replace IPA-soaked cleanroom wipers at the most advanced 300mm wafers fabs running 14nm processes, even on Hi-Vac chambers and photolithography equipment.
MiraWIPE’s interstitial, star shaped fiber contains variegated edges that enable particles, residues and liquids to be easily dislodged, entrapped and removed from critical cleanroom surfaces. This combination enables operators to use the MiraWIPE® Wiper with DI water, eliminating the need for IPA.
The Greener, Cleaner Cleanroom.
MiraWIPE® and DI water used together are an environmentally friendly, easy to implement, and cost-efficient green solution to the vexing EH&S issues plaguing cleanroom professionals.
Due to the high manual labor content and the availability of terminal sterilization steps, medical devices are manufactured primarily in ISO Class 6-8 clean rooms. While these clean rooms are designed to control particles, fibers, and bio burden, the numerous contact points between operators and the device mandates that robust cleaning procedures be in place.
For example, it is often standard practice that work stations are wiped down each time an operator approaches or leaves the station.
In addition to work stations, gowning rooms are routinely mopped before and after shift changes and breaks.
It is also known that, despite rooms passing airborne particle checks, large surface fibers and particles are ever present sources of contamination.
It is well recognized that an outside-in approach is the best way to keep work stations and devices free of contamination. Simply stated, keeping contamination out of the clean room is far easier than dealing with it at the workstation.
But we know in medical device clean rooms, several factors mitigate against this ideal situation.
Let’s focus on two: high traffic and the use of disinfectants.
Since operators are a large source of contamination, airborne particle counts are widely used to measure room cleanliness while in operation. Despite room counts being in control operators spend a great deal of time inspecting and cleaning large (50-150micron) fibers from devices. In addition, there are excursion events where for days it seems no device is in spec for cleanliness; this necessitates extra inspection, device cleaning, and in some cases non-conformity reports and CAPA’s (which are often closed by triple cleaning the room).
Device firms that have investigated the excursions find the FM population diverse in the extreme which make root cause analysis very difficult.
So what is happening and what can be done?
Let’s go back to the triple cleaning of the room. Given that this often gets the room back in control this suggests that more robust cleaning of the large floor, wall, and ceiling surfaces could be a starting point.
This has, in fact, been validated at several device manufacturing facilities. It turns out that the disinfectants, applied daily to floors and weekly to walls and ceilings, tack down particles and fibers turning these large surfaces into FM storage containers.
What is needed is a cleaning solution that allows these surfaces to be stripped free of the disinfectant residues so that the entrapped contaminants can be removed from the room. This is easier said than done as typical mops and wipers do not scrub free the built up residues.
To solve this issue Foamtec has developed the Sahara + mop system. This mop is constructed with a uniquely tough, resilient foam that will not scratch even the softest surfaces but that will dislodge fibers and particles entrapped in the disinfectant residues. The other component to the mop head is a ribbed microfiber fabric that entraps and removes the soils dislodged from the surface. Each material is optimized to clean different types of particles. The Sahara foam is ideal for large fibers and hairs while the microfiber and polyester fabric remove hydrophilic and hydrophobic soils and particles.
The following video shows how cleaning can easily upgrade the cleanliness levels in clean rooms where medical devices are manufactured.
For more information about the Sahara+ System visit our website: www.foamtecintlwcc.com