Responsible nations around the world are becoming very concerned over the continued use of the hazardous and toxic compounds used in the manufacturing process. The semiconductor industry, together with other global industries have been challenged by environmentalists to “green up” their operations. 

Mirachem® developed Mirachem 2780 for the semiconductor industry to solve the wafer dicing problem. It’s solution is non-toxic and biodegradable and used by many of the world's leading semiconductor fabricators. The characteristics of this solution have been developed around friction reduction, increased wetting and lubricity with low foaming to prevent drain overflow. 

Customers using Mirachem 2780 have noted an improvement in kerf quality, a reduction in wafer chipping and fracturing, an increase in blade life and cleaner wafer and bonding pad surfaces. They have also confirmed there are no ingredients in Mirachem 2780 which are harmful to semi-conductor wafers, devices, BGA's, MBGA'S or any other electronic materials.

Using sprayed D.I. water on wafer surfaces increases ESD from friction of water across the wafer creating poor wetting. This can create a dry spot where silicon dust will collect. Silicon particles can build up in the cut and cause chips, fractures or micro-fractures in the wafer.   

When silicon debris is washed across the surface of the wafer, it tends to cling to the bond pads. Once the silicon debris has attached to the pad, it requires a light to aggressive scrub to be cleaned. The bond pad with debris will reduce the bond shear strength and is suspect to cause long term failure.

Unevenly wet surface using just DI water 
and silicon debris on the pads after dicing.

Using Mirachem 2780 to clean bond pads and wafer surfaces improves the dicing process. Mirachem 2780 is designed to wet the surface evenly which reduces friction. By reducing friction, the chances of ESD, Silicon particle build up and debris are reduced. Less particle build up and a reduction in friction improves the cutting surface, which improves the saw’s performance and increases blade life.

Using Mirachem 2780 during the dicing process also requires less post dicing scrubbing.

Evenly wet surface using Mirachem 2780 
resulting in cleaner bond pads after dicing.

Mirachem 2780 suspends and removes submicron debris. With this particle suspension, the debris that was once free to adhere itself to the bond pads is now washed off during the dicing process and rinse cycles. Customers have noted that minimal to no post dicing scrubbing is required as an end result of using Mirachem 2780.  

Improving the saw’s performance, increasing blade life and cleaner bond pads improves the dicing process and increases yields.

Mirachem 2780 improves the quality and reliability of semiconductor devices.  When dispensed in a consistent ratio Mirachem provides the highest level of cleanliness and process improvement.   

During the dicing process silicon debris is pushed and washed from the kerf in all directions. The debris created is forced towards the bottom of the kerf creating excessive backside chipping.  Debris is also washed away from the cutting area only to reside heavily in the areas of poor wetting and especially clinging to the bond pads over the majority of the wafer. Minute amounts are forced between the blade and the kerf wall creating a poor finish.  

Mirachem 2700 Series are water-based detergent formulations. Detergents are molecules that consist of Hydrophilic (water loving) and Lipophilic (oil loving) components, as illustrated in Figure 3.

In hard surface cleaning, the lipophilic portion of the molecule is attracted to the particle and attaches to the particle, illustrated in Figure 4.

As more molecules attack the particle, the contact angle between the particle and the surface increases until the particle is removed from the surface, as shown in Figure 5.

As the detergent removes the particle, the hydrophilic (water loving) tails suspend the particle in the dicing water solution. This allows the particle to be washed away without leaving a residue.

The selection of the detergent (hydrophilic molecule and lipophilic molecule) in specific cleaning applications is dependent on the type of particles being removed and the method of cleaning. 

Mirachem 2780's detergent system was selected for its ability to remove particulate silica, with low foaming characteristics, low environmental toxicity and human safety. The specific molecule is proprietary.

The following report was to qualify Mirachem against four other dicing solution that are available on the market.  The customer was using one of the listed brands, but found the result to be unsatisfactory and the pricing too high.

• Device:  Not disclosed to the public
• Wafer material:  Silicon-on-insulator (SOI) bonded wafer substrate
• Wafer Size:  6-inch
• Wafer Thickness:  13-mils
• Die Size:  44 x 71 mils

• Dicing Tape:  NITTO SWT-10
• Dicing Wheel:  2-inch Resin Bonded Diamond Wheel, Hub Type
• Machine:  DISCO Full-Auto Dicing Saw

• Feed Speed:  15 mm/sec
• Spindle Revolution:  45,000 rpm
• Cut mode:   Saw-thru, Downcut, Unidirectional
• Cutting Water Resistivity:   1.0 =/- 0.2 megaOhm (thru CO₂ bubbler)

• Clean Time:   60 sec
• Clean RPM:   800 rpm
• Clean Water Pressure:   120 =/- 20 kgf/cm²
• Dry Time:   90 sec
• Dry RPM:   1,500 rpm
• Dry CDA Temp:   100 =/- 1- deg C
• Dry CDA Flow:   30 =/- 10 li/min

DI Water to Surfactant Ratio:  200 to 1

The results of the test can be seen below

The bond pads have been cleaned efficiently and evenly.  The results are caused by the ability to remove debris and to create an evenly wet surface.

The left pad is tainted with debris and the right is clean.  This is caused by uneven surface wetting.

These pads show an unevenly dirty surface.  This is caused by insufficient cleaning from the product.

These pads are covered in debris showing the fluid's inability to remove particles.

These pads appear to be attacked by corrosion or an aggressive type cleaning agent.

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