This ppt is very useful to know about the clean room....

1. Presented by,
Mr.S.Sivakumar
M.Tech(DCN)
Department of ECE
Kalasalingam University.

2.  Introduction
 Cleanroom definitions
 Parameters about clean room
 Characteristics about clean room
 Contamination & Measurement
 Cleaning & Materials Selection
 The user!!
 Protocols to improve control
 Conclusions
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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.  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!
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5.  Why Cleanrooms?
 First cleanrooms were in hospitals to prevent disease
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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
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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. 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. High Efficiency Particulate Air (HEPA) Filter:
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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. – 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.  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!
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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
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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
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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?
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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.
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15.  Efficiency depends of tackiness of roller, cleanliness
of tacky surface and softness of roller are also very
important
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16.  Choice of materials for supplies, equipment,
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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.“)
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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!!!
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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.  Liquid Crystal Institute(LCI).
 Pick up an appropriately sized coverall and put on, being
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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
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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
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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
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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
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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
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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!
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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
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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
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