16
COVER STORY
protects the substrate both against
unwanted process influences and damage
caused by unintended forceful closing of
the capsule. Thanks to the mentioned
features, the CyclopSealing capsule can
make almost any process more profitable
with an improvement in yield and less
wastage throughout the process of
manufacturing.
In order to create a product that met
the varying demanding customer needs,
extensive efforts in R&D were necessary.
From idea through design to final
product, CyclopSealing has had to survive
a rigorous testing procedure involving
intensive continuous quality enhancement
process.
Surface tension
optimisation
In order to make sure that the sealing
capsule complies with the industry
requirements a test model had to be
developed and tested in appropriate
conditions. The immersion chemistry had Above: Illustration showing encapsuled area of wafer
to fulfil requirements such as extremely that is not etched
low surface tension and the ability to Right: Test structure developed of peak to valley of 1µm
penetrate leakages. A tracer substance with deliberate irregularity in the area of the bearing
was also developed that can easily be
detected if the sealing has been breached.
The optimised media contains a based and the temperature stable up to into the next was completely automated
fluorescent tracer substance that emits 100
o
C. and shorter than 5 seconds. The whole
light if exposed to a UV light source even temperature stability test consisted of the
in minute levels. The media is aqueous Temperature change sequence in box to the left.
stability
Whole Temperature
During a wet process a substrate is Mechanical stress due to
exposed to different temperatures and has media flow and relative
Stability Test
to sustain its specific temperatures as well movement
Step 1: 300 seconds 20
o
as the variation of the temperatures. Of Not only thermal stress can endanger the
∞C
course what is valid for unsealed impermeability of the capsule. Also
Step 2: 600 seconds 90
o
∞C
substrate is also applicable to the sealed relative movements like liquid flow or
Step 3: 600 seconds 20
o
∞C
substrate. The sealed substrate was active agitation, as is necessary in some
Step 4: 600 seconds 80
o
∞C
immersed into a recirculation tank cases, create a disturbance in any ideal
Step 5: 600 seconds 20
o
containing the test chemistry as in figure system and would need to be investigated.∞C
Step 6: 600 seconds 70
o one and exposed to typical flow conditions In order to get experience with conditions
∞C
Step 7: 300 seconds 20
o
that exceed the normal requirements the
∞C
as they are used for cleaning and etching
processes. The transport from one tank following test scenario was developed that
contained deliberate strong agitations.
Wet Test (Agitation)
Influence on
Step 1: 300 seconds 20
o
C agitation 0.0 Hz
impermeability
Step 2: 600 seconds 90
o
C agitation 0.8 Hz
Structures on top of the substrate may be
in the area of the bearing contact. Due to
Step 3: 600 seconds 20
o
C agitation 0.8 Hz
production and process conditions this is
Step 4: 600 seconds 80
o
C agitation 0.5 Hz
not avoidable and poses a potential threat
Step 5: 600 seconds 20
o
C agitation 0.5 Hz
to the impermeability of the system.
Step 6: 600 seconds 70
o
C agitation 0.3 Hz
Regardless of these potential problems it
Step 7: 300 seconds 20
o
C agitation 0.0 Hz
is important that the sealing capsule is
able to cope with demanding
www.euroasiasemiconductor.com November 2008
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