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ADT ADVANCED DICING TECHNOLOGIES

ADT 8000 NextStep Laser Scribing System 

ADT’s Model 8000 NextStep system removes only non-silicon elements from the streets leaving the silicon wafer bare and virtually unaffected. The wafer can then be diced using a standard mechanical dicing process.

MODEL 8000 NextStep 

ADT NextStep Laser Scribing System

Process Advantages:

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Silicon transparency to the radiation

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No micro-cracking and no delamination

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One pass process at 600 mm per second

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Attractive cost-of-ownership

NextStep (click on picture for enlargement)

TECHNICAL NOTES 
 Get the NextStep product catalogue  ADT NextStep Laser Scribing System
FEATURES 

With ever-increasing transistor density, shrinking metal lines and gate dimensions, producers are forced to use metals of higher conductivity such as copper, "low-k" isolation materials such as "black diamond" and more test pads. 
These new manufacturing standards set a different threshold for wafer singulation whereby traditional step cut dicing no longer meets the quality requirements and cost targets for manufacturing. 
ADT meets the market challenge with a new, revolutionary type of laser for wafer scribing

WHITE PAPER 

NEXT GENERATION LASER SCRIBING FOR DICING COMPLEX SILICON WAFERS

The well- known law named after Gordon Moore predicts the doubling of integrated circuit (IC) performance every 18 to 24 months. The semiconductor industry owes part of the uninterrupted continuation of this trend to two significant changes it has recently adopted. The first is the transition of metal interconnects from aluminum to copper, due to the higher electrical conductance of the latter. The second is the conversion from the use of traditional silicon dioxide dielectrics to a new class of materials with lower dielectric constants, appropriately termed “low-k” materials. Both these changes, although extremely beneficial to IC performance, have been found to result in undesired effects on the dicing process, in which the silicon wafer is separated into individual die.

Copper is considerably more ductile than aluminum resulting in premature clogging of the dicing blade, which in turn leads to increased loading and excessive chipping that deteriorates the cut quality. The porous organic and other materials that make up the group of low- k materials are more fragile than silicon dioxide and are hence much more susceptible to chipping and cracking during dicing. Not only has the nature of the dielectric material changed, but also the thickness of the active layers has increased up to a thickness of 10 microns. Additional developments in the fabrication of integrated circuits have resulted in further challenges to the dicing process. The number of metallic layers has steadily increased (with eight layers not uncommon) and the incorporation of multiple functions on a single chip has led to larger die that call for polyimide coatings to mediate thermo- mechanical effects between die and package. Both the additional metal and the presence of polyimide lead to premature blade clogging and an unstable dicing process.

The current solution to the problem of dicing complex silicon wafers is based upon a two- step process. In the first step, a very shallow cut is made into the wafer in order to remove only the non- silicon components. This step is usually performed at very low feed rates (less than 10 mm/s) in order to attempt to overcome the difficulties presented above. In spite of the low feed rate and the attempts of blade manufacturers to offer specific products for low-k materials, this first cut is often accompanied by severe chipping, metallic smearing and layer peeling. In a second dicing step, the remaining wafer is cut all the way through at standard dicing feed rates.

Clearly, the main obstacle to lowering cost of ownership in wafer singulation is the problematic first step in the process. Accordingly, the industry is looking at alternatives to this step, most often in the form of laser scribing.

Out of several laser- based solutions presented for singulating low-k wafers, the one offered by Advanced Dicing Technologies (ADT) stands out in its simplicity, ingenuity and cost- effectiveness. The patented technology introduced by ADT makes use of a low- power CO2 laser to ablate only the non- silicon components in the wafer streets. The silicon itself is transparent to the specific wavelength used and remains virtually unaffected by the radiation. Not only does the radiation have no direct effect on the silicon, but unlike other laser- based solutions that have a detrimental effect on die strength, also secondary thermal effects in the ADT system are negligible due to the very limited heat- affected zone of the CO2 laser.

After laser-scribing with the ADT system, the clean- street wafer can be traditionally diced on a dicing saw. Due to the unprecedented feed- rate of up to 600 mm/s at one pass, the ADT system can provide scribed wafers for two to three twin dicing systems thus providing a truly cost- effective solution to the industry. With the high throughput of the process, its excellent cut quality and the minimal capital expense required, ADT have presented the industry with a truly winning combination.

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Last modified: 2016-08-22