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.

 

 

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)

 

 

 

Very Large Trepanned “Hole” or small resized wafer, whichever you want

Circular cuts in silicon wafers.
3mm (.125″) dia. Thickness is 175mm (.007″).

 

 

 

 

 

 

 

Array of Laser Drilled Percussion Holes in a Silicon Substrate

in 625um thickness Si

Overall 12mm dia

Small hole dia 0.125mm (125um)

 

 

 

 

 

 

 

 

 

Profile of Laser Trepanned Hole Drilled in Silicon

0.700mm dia.
Laser entrance side, cleaned mechanically. Thickness is 0.5mm (.020″).

 

Get More Info…

 Get More on Laser Hole Drilling

 

 

 

 

 

 

 

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

 

 

 

 

 

 

 

Laser Cutting a Silicon Edge at an Angle

Fancy laser cutting at a 45 degree angle.

 

 

 

 

 

 

 

 

Guidelines on Si Processing by Q-switched YAG Laser

 

These first 3 pertain to holes, cuts or scribes:

 

• Max Depth: 1mm
• Min Depth: none
• Typical Depth of Penetration: 0.5mm

 

These next 6 pertain to drilling holes only:

 

• Max Dia of Trepanned Hole: none
• Min Dia of Trepanned Hole: 50 microns
• Max Dia of Percussion Hole: 50 microns (up to 25 mil thickness Si)
• Min Dia of Percussion Hole: 15 microns
• Taper of Trepanned Hole: (ask us)
• Taper of Percussion Hole: (ask us)

 

The next 2 pertain to cutting or scribing.

 

• Kerf Loss: Width of cut for 0.5 mm thick Si (full penetration cut) is 50 microns at top and 25 microns at bottom of cut.
• Edge taper is best evaluated on samples we create for you.

 

These last 2 pertain to all: drilling, cutting and scribing.

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.

 

We have two basic methods of working silicon without contamination (others for MEMS):

 

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.

 

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.