IntegraBLOG

CORWIL's Commitment to it's Customers

Posted by Susan Campbell on Mon, May 08, 2017 @ 10:46 AM

When CORWIL was approached by a medical customer that had developed a product that required a very small and strong die, CORWIL collaborated with them to utilize Dice Before Grind (DBG) in order to adhere to the customer’s very tight and unconventional package requirements. Using DBG reduced die breakage and chipping that can be caused by conventional methods.

CORWIL’s commitment to problem solving, delivering quality products and acquiring the best equipment resulted in a happy customer as well as CORWIL successfully taping 1 million die in the month of March on their recently attained Muhlbauer Tape and Reel system.

Pic2.jpg


Request a quote

Dice Before Grind (DBG) for Medical Devices

Posted by Jonny Corrao on Thu, May 12, 2016 @ 12:11 PM

CORWIL was recently approached by a medical customer who had developed a tiny wearable device that included a small bare die with innovative packaging. The product required a very small and strong die due to the customer’s very tight and unconventional package requirements. The die were on a 300mm wafer and had tight streets and low-k dialectrics.

Knowing that the backside and edge quality were key, the CORWIL team used Dice Before Grind (DBG) to reduce die breakage and chipping typically caused by the conventional method. DBG reverses the usual process of fully dicing the wafer after grinding. In DBG, the wafer is first trenched, or partial-cut, to a depth greater than the final target thickness. The wafer is then thinned to the final target resulting in die separation. After grind, the wafer goes to the in-line DBG Mounter, which mounts the wafer and gently peels off the protective grinding tape, completing the process.

Since the die are singulated at the final target thickness, wafer-level breakage is greatly reduced. Additionally, as a result of the die separation occurring during the grinding process, the backside chipping associated with thin-wafer dicing is kept to a minimum. DBG can also provide improved die strength depending on the application. For these reasons, DBG is an excellent process for processing wafers with high-quality backside requirements.

Top: DBG Bottom: No DBG
 
 
Corwil-medical-device-technology

Processing III-V and Other Non-Silicon Materials 

Posted by Dan Miranda on Mon, Sep 21, 2015 @ 07:24 AM

CORWIL Technology successfully processes a number of materials through its wafer processing facility. While Silicon is the majority of material processed we’ve been seeing increasing trends in such materials as SiGe and GaN, as well as GaAs and InP. Each material, wafer size, and customer specification requires attention to detail and careful recipe cultivation, as well as specialized grinding and cutting tools. CORWIL’s standardization on DISCO equipment has allowed us to work closely with our vendors and be able to process multiple materials on different machines.

Backgrinding:    CORWIL uses automated and semi-automated Disco equipment and grind wheels to process wafers.  Speeds, grind wheel grits, and selection of appropriate WSS (wafer support system) tapes all play a role in processing exotic materials.  Through repeated process verification activities, we select grind wheels and parameters that are suitable for each wafer’s specific characteristics resulting in the optimal grind conditions. 

Optimal grinding conditions enable low-load grinding for both coarse and fine grinding by decelerating the feed speed of the grinding wheel spindle as the final finishing thickness is approached. Further, applications such as accelerating at the wafer vacuum table while decelerating the spindle rotation speed are effective as countermeasures to reduce edge chipping.

The following are some considerations when backgrinding some different materials:

  • Grinding of GaAs (Gallium Arsenide) wafers tends to cause plucking (holes made by peeling) or scratching on the surface. In addition, depending on the difference of the wafer manufacturing process, the process ability of the GaAs wafers varies.
  • SiC (Silicon Carbide) is a very hard material and extremely difficult to grind.  Process time is much slower  compared to Si. Using Disco’s GS08 series grind wheel, high quality SiC processing  is possible for this extremely hard material. .
  • InP (Indium Phosphide) Optimization of wheels and processing parameters enables high quality processing of InP used in high-speed devices.  Selection of optimal  processing parameters improves the condition of the processed surface compared with the traditional methods.
  • Grinding of BSM (Backside Metallization) Au (gold), Ag (silver) and other exotic metals can be removed from the backside of wafers by utilizing special Disco grind wheels  coupled with optimum grinding parameters and interval dressing.

The following pictures are special III-V backgrinding processes developed by CORWIL. GaAs and InP wafer diameters ranging from 3-8 inch mounted on WSS tape or sapphire carriers can be thinned to 100µ or less succesfully. 

CORWIL-GaAs-wafer

6-inch GaAs wafer mesa etched before grind, process development for ultra stable laser optics by Crystalline Mirror Solutions

CORWIL-GaAs-mesa-sigulation

GaAs mesa singulation after grind, in this case up to ~50-mm diameter die generated via an "etch-to-core" process

CORWIL-GaAs-wafer-portions

GaAs wafer portions mounted on sapphire

CORWIL-wafer-thinning

GaAs wafers thinned on sapphire carriers

CORWIL-wafer-thinning

100mm GaAs wafers thinned on sapphire

CORWIL-InP-devices

InP devices mounted and thinned on handle

CORWIL-InP-wafer

InP wafers mounted on WSS backgrind tape

CORWIL-InP-wafer

InP wafers “gang” mounted and thinned

Dicing:   Dicing saws use dicing blades to cut silicon, glass, and ceramic work pieces with a high degree of accuracy. Fully automatic dicing saws  perform the entire process sequence: loading from the cassette, alignment, dicing, cleaning/drying, and unloading to the cassette, in a completely automated fashionCORWIL utilizes different dicing blades and saws as well as advanced recipe development to successfully dice silicon, III-V materials and other exotic materials such as Sapphire.

Backside chipping caused during the dicing process tends to increase on exotic materials and thin wafers. Finer grit blades and the use of surfactant lubricity can reduce backside chipping. In general, a finer-grit blade imparts less of a shock to the work piece, thereby reducing backside chipping. DISCO's dicing blades are used with dicing and cutting saws to groove, cut, and dice silicon, compound semiconductors, glass, ceramics, crystals, and almost any other material. They are one key to DISCO's excellence in Kiru (dicing) processing

The following are some considerations when dicing  different materials:

  • Dicing SiGe:  While very similar to dicing Silicon, Silicon Germanium wafers have a number of nuances that call for careful development of dicing recipes and use of alternative blades.  We see increasing use of SiGe by our customers and have developed techniques to enhance edge quality of dice.
  • Dicing GaAs - During dicing, breakage and cracking can easily occur in the GaAs wafer because the material is very brittle.  A combination of an ultra-thin diamond blade and an aluminum hub provides enhanced operation efficiency and stable cutting results. In combination with DISCO's vast application knowledge, these blades provide excellent cutting results when dicing silicon wafers and compound semiconductor wafers such as GaAs.
  • Dice before Grind – DBG:  CORWIL has successfully processed a number of different materials using the DBG process including SiGe and GaAs.  DBG reverses the usual process of fully dicing the wafer after grinding. In DBG,  the wafer is first trenched, or partial-cut, to a depth greater than the final target thickness.   The wafer is then thinned to the final target resulting in die separation. After grind, the wafer goes to the in-line DBG Mounter, which mounts the wafer and gently peels off the protective grinding tape, completing the process.
CORWIL-dice-before-grind

Because the die are singulated at the final target thickness, wafer-level breakage is greatly reduced. Additionally, as a result of the die separation occurring during the grinding process, the backside chipping associated with thin-wafer dicing is kept to a minimum. DBG can also provide improved  die strength depending on the application. For these reasons, DBG is an excellent process for processing  wafers with high-quality backside requirements.

DGB

 

No DGB

CORWIL-dice-before-grind

 

Scribe and Break:  CORWIL also processes die using scribe and break technology.  This type of technology works well with brittle materials such as Indium Phosphide and GaAs. 

The following is an overview of our guidelines for our scribe and break process:

CORWIL-scribe-and-break

Some Caveats of our guidelines:

  • Thicknesses greater than the specified optimal conditions will be evaluated by CORWIL Engineering
  • Street widths narrower than specified will be evaluated by CORWIL Engineering
  • Maximum wafer size is 5”
  • Irregular shapes and wafer fragments and portions can be processed.

CORWIL Technology uses world class equipment and processes to process Silicon, III-V and other exotic materials.  CORWIL’s work with Disco, our customers, and a long history of recipe development through Design of Experiments ensures our customers’ continued satisfaction by consistently providing  high-quality results.

For more information on this or any of CORWIL's other services please give us a call at 408-618-8700 or fill out our Quote Request Form.

 

 

Click to edit your new post...

Tags: DBG, Dicing, Backgring

Want to Learn More About Die Singulation?

Posted by Jonny Corrao on Wed, Nov 06, 2013 @ 01:00 AM

wafer-dicingDie singulation is the process of isolating individual IC’s from a wafer. There are a variety of methods for die singulation with the most common being conventional dicing, laser dicing, scribe and break, and dice before grind (DBG). 

Conventional dicing is the current industry standard for die singulation. Conventional dicing typically utilizes diamond enriched resin-bonded blades on high precision saws to cut through materials like silicon, alumina nitride, sapphire, gallium nitride, and mold compound.

Conventional dicers are equipped with a porous ceramic chuck to hold the work piece during
dicing. A blade mounted on a high speed spindle cuts the material while high pressure water nozzles flood the work piece and blade to provide cooling. Standard dicing feed rates range from 0.5 to 3.0 inches per second depending on the material, material thickness, and quality requirements.

In addition to providing cooling...

The chilled deionized water used during dicing provides lubrication to remove particles generated during saw. Re-ionized water can be used instead of deionized water to lower resistivity and minimize ESD effects on ESD sensitive products. Surfactant can also be added to the process water for ESD purposes, additional lubrication, and to minimize corrosion in copper embedded bond pads.

The blades used in conventional dicing vary in size depending on the material thickness and saw street width. The saw street is the distance between the outer edge of each die on a wafer. As the blade cuts through the material a saw kerf is generated. The kerf includes the extra material removed in addition to the blade width. The saw kerf is typically an additional 10-20µm wider than the actual blade width. On a 40µm wide blade, for example, the actual material removed, or kerf, would be 60µm. As a result, blade selection is highly dependent upon street width. 

Material thickness also plays a critical role in blade selection. With thick materials wide blades are a necessity in order to provide adequate blade strength to cut through more material. Additionally, the dicing blade edge requires an adequate clearance and engagement area to effectively cut. The clearance required for a blade is called the blade exposure. A tall skinny blade is more unstable and prone to blade wobble and breakage when cutting thick materials. Therefore, material thickness and sufficient exposure is another key variable in blade selection. As a rule of thumb, the thicker the material the wider the blade needed, the taller the exposure and, in turn, the wider the required street width.

Finally

With conventional dicing, chipping is the main quality concern. Chipping quality is governed by feed rate, cut mode, blade width, blade concentration, and blade grit. Typically, the higher the feed rate the larger the chipping. Two different cut modes are typically used, step cut and single pass. Single pass uses one blade to cut all the way through the material. Step cut uses two blades to cut at different depths in the wafer. Single pass provides greater throughput, but larger chipping compared to step cut. Blade grit and concentration are selected based on whether topside or backside chipping is critical and whether metal peeling or chipping is of concern.