Clean room

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Clean room

  1. 1. Presented by, Mr.S.Sivakumar M.Tech(DCN) Department of ECE Kalasalingam University.
  2. 2.  Introduction  Cleanroom definitions  Parameters about clean room  Characteristics about clean room  Contamination & Measurement  Cleaning & Materials Selection  The user!!  Protocols to improve control  Conclusions 11/13/2013 2
  3. 3. MEMS is the acronym of Micro Electro Mechanical Systems. It is a highly miniaturized device or an array of devices combining electrical and mechanical components that is fabricated using integrated circuit (IC) batch processing techniques and can range in size from micrometers to millimeters. In Europe it is called Microsystems technology (MST).
  4. 4.  It is important for users to understand concepts behind clean processing  Benefit from the experiences of others (standards, anecdotal information(reliable))  Impact that a single user can have on overall process yield can be huge! 11/13/2013 4
  5. 5.  Why Cleanrooms?  First cleanrooms were in hospitals to prevent disease     transmission and infection in operating rooms (over 100 years ago!) Valuable tool to prevent particulate and bio contamination Most well known use is in semiconductor industry, but also essential in pharmaceuticals, flat panel displays, space program, photonics, life sciences, industrial (painting, assembly), etc. Essential for LCDs because of coating processes, small cell gaps Cleanroom itself is only part of the solution 11/13/2013 5
  6. 6. Micro-fabrication needed a very clean environment to prevent dirt or other particles from contamination the MEMS devices . Two pictures in clean room.
  7. 7. Yellow room is a special area in CLEANROOM. It is used for photolithograhpy process. Because of the sensitivity of PR,the wafers covered by PR must be used in yellow room. Once such wafers(substrates) are brought outside the yellow room, most of them might be exposed by UV.
  8. 8. High Efficiency Particulate Air (HEPA) Filter: – – – – Most common type of clean room air filter High efficiency, low pressure drop, good loading characteristics Uses glass fibers in a paper-like medium Are rated by their particle retention: • A true HEPA-rated filter will retain 99.97 % of incident particles of 0.3 mm or larger. Ultra low particulate air (ULPA) Filter: This filters are 99.9995% efficient in removing particles 0.12 µm and larger. ULPA filters are used in air filtration and purification systems to control airborne particulate levels and to stop the spread of toxic agents and infectious diseases.
  9. 9. – Air is recirculated through HEPA filters with about 20 % make up. • Vapors are entrained, so contamination potential is very high. • Extensive gas detection and alarm systems are installed. – Temperature is controlled to 68 - 72 °F. – Humidity is controlled to 40 - 46 % RH. – Room is held at positive pressure . • Typically 0.1 in of H2O for Class 100, Class 1000, and Class 10,000 • Typically 0.3 - 0.4 in of H2O for Class 1 and Class 10 • Positive pressure constantly blows dust OUT • (Biohazard rooms operate at negative pressure to keep bugs IN) • Doors open inward, so room pressure closes them shut .
  10. 10.  Positive Pressure / Airflow  Keeps contamination out of the work area  Depends on clean air input  Filtration  Development of effective filtration revolutionized industry  HEPA (High Efficiency Particulate Air) and ULPA (Ultra Low Particulate Air) Filters  Materials Selection  User Protocols  Cleaning  All are very important! 11/13/2013 10
  11. 11.  Particulate—encompasses most contamination  Chemical—films, vapors, etc.  Biological—bacteria, viruses, etc.; for our purposes, treat as particles  Similar concerns for rooms & equipment as for substrates 11/13/2013 11
  12. 12.  Critical to remove contaminants that cannot be removed by air handling  Important to follow procedures appropriate to your application  What is appropriate for one industry may not be appropriate for another  Most important thing is to develop standard procedures and FOLLOW THEM 11/13/2013 12
  13. 13.  The efficiency of these cleaning methods depends on the surface being cleaned  Rough or pitted surfaces are more difficult to clean  Sharp corners are difficult to clean  Why are inside surfaces of cleanrooms smooth? 11/13/2013 13
  14. 14.  Dry and wet  Dry has low (<25% ) efficiency for particles smaller than 10 microns (about .0005 inches)  wet uses liquids which result in greater force on the particles and hence better cleaning.  Most facilities use DI(Distilled Water) water or isopropyl alcohol with disinfectant.  The choice depends on what works, cost, history, etc. 11/13/2013 14
  15. 15.  Efficiency depends of tackiness of roller, cleanliness of tacky surface and softness of roller are also very important 11/13/2013 15
  16. 16.  Choice of materials for supplies, equipment,     gowning, etc. is important “Clean” materials can become dirty!! Look for easy-to-clean materials Triboelectricity can cause static problems, as can low humidity—this exacerbates contamination problems Biofilms!!(Biofilms form when single microorganisms attach to a hydrated surface and undergo a "lifestyle switch.“) 11/13/2013 16
  17. 17.  Truth: Manufacturers can achieve similar yield results using cost effective flow hoods and isolation chambers as with full-blown central cleanrooms  BUT: user behavior is much more critical in these areas!!! 11/13/2013 17
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  19. 19. Before any work can be done in the cleanroom facility, users must gown up in appropriate cleanroom garments. These garments are located in a separate room at the top of the ramp leading away from the entrance door to the facility. Nothing should be taken into the gowning room. All clothing and miscellaneous items (keys, cell phones, sweaters, notebooks) that are not specifically qualified for use inside a cleanroom must be left outside the entrance to the facility, not in the gowning room. These items will only contaminate the cleanroom garments which are hung there. Please leave these extraneous items in your office or car for the highest degree of safety. Items may be left on the bench used for putting on shoe covers or on the adjacent coat rack at your own risk.
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  21. 21.  Liquid Crystal Institute(LCI).  Pick up an appropriately sized coverall and put on, being     careful to avoid allowing coverall to touch floor Put on plastic shoe covers (booties) over your shoes in the hallway If you wear boots or other heavy contaminating shoes, consider keeping a pair of sneakers in your office for use in the cleanroom. Put on hairnet, Pick up an appropriately sized head cover and put on. Put on safety glasses and proceed to air shower 11/13/2013 21
  22. 22.  Not wearing Safety Glasses  Improper gowning  zippers, snaps, masks  Non-cleanroom materials in cleanroom  paper, cardboard, personnel items  Not cleaning up after you are finished  General conduct  Fast motions, incorrect carrying of materials  Remember laminar flow; minimize turbulence 11/13/2013 22
  23. 23.  Minimize sources of contaminants  No smoking  No cosmetics  Avoid high particulate clothing, such as wool sweaters  Cover up! Uncovered skin can lead to more contamination 11/13/2013 23
  24. 24.  Follow gowning procedures and restrict materials used in cleanroom  An educated worker is essential to proper job performance; workers should be well versed in the how and why of their job 11/13/2013 24
  25. 25.  Cleanroom environment is very fragile!(Easily broken or damaged)  Your actions have impact on other users  Important to follow procedures EVERY TIME  Make sure fellow workers follow procedures as well; nothing wrong with pointing out mistakes  Be an active participant: keep an eye out for areas that can be improved 11/13/2013 25
  26. 26.  Bring only required materials into cleanroom; if it is not necessary to perform the task, it should not be there  Personnel: only required personnel should be in the clean space  Reduce clutter—do not store materials in clean areas unless they have to be there! 11/13/2013 26
  27. 27.  Follow exact procedures every time  Wipe down surfaces with cleanroom wipes before and after every usage  Remember: this can seem tedious and unnecessary, but is essential to keeping the cleanroom maintained at its highest levels 11/13/2013 27
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  30. 30.  Contamination control is a continuous battle  User behavior has a critical impact on contamination  Proper procedures must be followed at all times  Think about your actions! Be an active participant 11/13/2013 30
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