"Stealth dicing" is a dicing method that forms a modified layer in the workpiece by focusing a laser inside the workpiece, and then a tape expander is used to separate the die.
Stealth dicing illustration
Before tape expansion
After tape expansion
Merits of stealth dicing
Able to suppress cutting waste because it modifies an internal portion of the workpiece. Therefore, it is suitable for workpieces that are vulnerable to contamination.
It is a dry process that does not require cleaning, therefore it is suitable to processes (such as MEMS) that are vulnerable to load.
Greatly contributes to street reduction because the kerf width can be made narrow.
Stealth dicing example
The profile of a MEMS die, such as one with a hollowed structure, or one that is already embedded with complicated minute elements, is generally not strong enough for cleaning water or the dicing load. Stealth dicing can be expected to result in high-quality processing of MEMS because it does not use water for processing or cleaning, and there is little or no damage to the die front or back surfaces.
MEMS photograph after stealth dicing
Stealth dicing is expected to increase the number of die that can be obtained from a wafer compared to normal dicing because it is possible to make the necessary street width (cut width) narrower. This is a particularly effective processing method for long shaped die, such as line sensors.
Comparison of the number of die that can be obtained from one wafer
The number of die obtained from one wafer increases by reducing the street width on a wafer with long-shaped dies.
A Hasen Cut is a method that cuts while repetitively turning the laser ON/OFF at a set cycle during laser processing. It is possible to process various shapes depending on the ON/OFF setting.
Hasen Cut application example
- Systematic complex die size wafer cut
By using the Hasen Cut, it is possible to process a wafer with combinations of irregular die shapes that could not be realized with the existing laser full cut processing or a blade dicer.
- Processing irregular shaped die
This cutting method can efficiently process workpieces like polygon shaped die, such as hexagons and octagons. Depending on the conditions, it is also be possible to process irregular shaped die.
Photograph of a hexagon die process
- Die offset processing
By applying the Hasen Cut, the dicing street can also support intermittent die layout, as shown in the illustration below. This is effectively useful for large die sizes, high-priced wafers or long die, and enables increasing the number of die that can be obtained.
Stealth dicing compatible machines
・Max. φ8-inch wafer processing
・Frame handling type
・Max. φ300 mm wafer processing
・Wafer direct handling type