Semiconductors… microcircuits and microchips - manufacturing
requires very precise condition to be maintained in the manufacturing/
processing area. Components used in assembly /processing of semiconductors
are generally hygroscopic and thus highly susceptible to high humidity
conditions.
A high Humidity condition causes operational
failure of chips, improper adhesion, corrosion in circuit points and
many other problems.
Humidity Control…. An important variable
to -
· Prevent corrosion of 'Circuit Points'.
· Prevent condensation on microchips circuit surface.
· Protect equipment
· Better adhesion of photoresists
THUS HUMIDITY CONTROL BECOMES A MUST
IN
1…Assembly Area
In the production of semiconductors and integrated circuits excessive
moisture adversely effects the bonding process and increases defects.
Photosensitive polymer compounds called photoresists are used to
mask circuit lines for etching process. Due to their hygroscopic
nature they absorb moisture resulting in the microscopic circuit
lines being cut or bridged, leading to circuit failure.
2…Wafer Fabrication Area
During wafer manufacture the spinners spray developer on the wafer
surface, causing the solvent present on the wafer to evaporate rapidly,
thereby cooling the wafer surface. This results in condensation
of water vapour from the air on the wafer surface. This extra water
on the wafer causes characteristics of the developer to change.
The resist also absorbs the moisture causing the polymer to swell.
Controlling relative humidity at 30% eliminates the possibility
of the cooling the wafer surface lower than the dewpoint of the
air surrounding the wafer surface, thus preventing failure and spoilage.
3…. Photo Lithography Room
Conditions in photolithography room need to maintained between 20%
to 35% RH at about 700F. Excessive moisture causes the silica to
absorb moisture, resulting in improper adhesion of photoresist leading
to stress fracture and surface defects.
4…. Faster Vacuum Pump Down
If humidity levels are high, operation of vacuum equipment like
cryopump is slowed down due to large load of water vapour. If the
RH levels can be maintained around 30-35% than the reduced considerably
resulting in increased batch processing speed.
5…for Protection of EPI equipment
Water vapour or moisture condenses on chilled surfaces of epitaxial
equipment corroding of components resulting in operation failure
and slow down of the process.
Bry-Air Desiccant Dehumidifiers can effectively maintain the most
stringent humidity conditions required for semiconductor manufacturing
areas, since they are capable of maintaining RH as low as 1% or
even lower at a constant level, regardless of ambient conditions.
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