A Laserod speciality is coring (resizing), dicing and
scribing of silicon wafers,
substrates, and laser machining silicon devices such as
sensors, detectors, and solar cells
We laser cut silicon
wafers
such as coring or resizing by downsizing semiconductor wafers and laser
machining sensors, solar cells,
MEMS and
other photovoltaic devices as shown below. Silicon wafer
dicing by laser scribing is a two step scribe and break
process.
For information on laser hole drilling in silicon -
go HERE.
Our standard kerf loss is 30 microns. 10um is
available on special order.
Laserod's Wafer Processing
Services:
Resizing, coring, laser scribing, hole drilling,
singulating, grinding/polishing, laser
marking, laser dicing, flat or notch cutting, thinning by
grinding/polishing, and backside laser scribing.
Others are video registration
through the laser focusing lens giving a magnified view
of the worksite, topside or bottom side laser cutting or
scribing, and minimizing contaminants with vacuum
collection system - primarily used in laser scribing,
not cutting. Laser debris on top of the wafer
especially after cutting can be further minimized by use
of a protective layer of photoresist which is cleaned
off by our customer.
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Silicon Wafer Coring (Resizing) by Laser
Cutting
A commonly performed job is resizing
12" to 8" as shown here. Other
common downsizings include: 8" to 6";
6" to 4"; 12", 8", 6"
or 4" down to multiple 2" wafers. Practically
any kind of downsizing (coring) by laser cutting is
possible. Ask us. If you
are interested in buying a laser coring machine,
go
to (Model SIR catalog) |
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Very Large Trepanned "Hole" or
small resized wafer, whichever you want
Circular cuts in silicon wafers.
3mm (.125") dia. Thickness is 175mm
(.007").
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Array of Laser Drilled
Percussion Holes in a Silicon Substrate
in 625um thickness Si
Overall 12mm dia
Small hole dia 0.125mm (125um)
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Profile of Laser Trepanned Hole
Drilled in Silicon
0.700mm dia.
Laser entrance side, cleaned mechanically.
Thickness is 0.5mm (.020").
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Trepanned Silicon Hole Drilling
and Laser Scribing
0.125mm (.005") dia. holes
Debris is from a Styrofoam cup
used to gently but effectively clean off laser
debris - a nice mechanical cleaning trick. Thickness 0.5mm. Note the laser
scribes at lower left - for Silicon Wafer Dicing
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Laser Cutting a Silicon Edge at
an Angle
Fancy laser cutting at a 45
degree angle.
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Guidelines on Si Processing by
Q-switched YAG Laser
These first 3 pertain to holes,
cuts or scribes:
These next 6 pertain to drilling
holes only:
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Max Dia of Trepanned Hole:
none
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Min Dia of Trepanned Hole:
50 microns
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Max Dia of Percussion
Hole: 50 microns (up to 25 mil
thickness Si)
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Min Dia of Percussion
Hole: 15 microns
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Taper of Trepanned Hole:
(ask us)
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Taper of Percussion Hole:
(ask us)
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The next 2 pertain to
cutting or scribing.
These last 2 pertain to all:
drilling, cutting and scribing.
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Laser Debris: entrance
side only, none on laser exit side.
Debris field is an easily removable haze.
If desired, remove with Q-tip, Styrofoam,fi
DI water, ultrasonic cleaning, etc. For MEMS
devices we use special techniques.
Laser processing of silicon
naturallly creates a hazy residue of
redeposited silicon particles, again on only
one side.
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We have two basic methods of
working silicon without contamination (others for
MEMS):
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Method #1: Back side drilling,
cutting and scribing of silicon
Backside work requires
registration to the front side which is
achieved by the use of custom optical
registration providing precise location.
Method #2: Front side
drilling, cutting and scribing of silicon
Registration is through the
laser focusing lens, allowing us to see with
the same magnification as the laser sees.
Fiducials work great for alignment. We align
to +/- 5 to 10 microns typically. We can
increase the laser magnification and improve
this, if required.
Contamination control
techniques include the use of
photoresist or equivalent coatings.
There are no post laser marks left on the
silicon after cleaning off the coating. The
coating must be removed, posing a problem for
some devices.
Other contamination controls
are the use of low power laser processing to
minimize particulates and the use of vacuum
exhaust. We can process parts in a full clean
room.
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Five Applications of Laser Machining
in Silicon
Application # 1: Wafer
Scribing & Resizing
Laser scribes are performed around the wafer to
trim it to a specific size. An example is
wafer coring (resizing) to reduce a large wafer to a smaller
size. This is actually cutting, not scribing.
Wafer scribing for "scribe and break"
is typically to a depth of one third the wafer
thickness. If the penetration is completely
through the wafer, it is called "cutting" as
contrasted to "scribing" which is a
groove to a specified depth. We
perform precision resizing and can
"round" laser resized silicon wafers for
your automatic handling equipment.
Application # 2: Via Drilling
Allows front to back surface contacts. Small
percussion holes and trepanned larger diameter holes
are both done.
Application # 3: MEMS
Micro-electromechanical systems devices (MEMS) are
laser machined to provide channels, pockets and
through features (holes) with laser spot sizes down to
10um and positioning resolution of 2-5um.
Channels and pockets allow the device to flex. Our
backside processing techniques are particularly
applicable.
Application # 4: Wafer
Flats
Additional Wafer Flats to aid
downstream wafer processing. By adding another
flat to the wafer, it is possible to handle the wafer
with greater ease during the production process.
Application # 5: Metal
Contact Isolation
Involves laser cutting for electrical
isolation. Depths of the cuts can be to 5-6 mils
and widths down to 0.5 mil.
Whatever your requirements for silicon
processing are, we are pleased to discuss it with you.
Please call, e-mail or fax.
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