December, 7 2015
DISCO has developed a unique Laser Lift-off optimal for high brightness vertical structured LED manufacturing
We are now accepting requests for test cuts
DISCO Corporation (Head Office: Ota-ku in Tokyo, President: Kazuma Sekiya) has developed a unique Laser Lift-off (LLO)*1 which realizes reduced equipment maintenance time and a more stable processing quality compared to existing products. This new technology contributes to not only to the high-yield and low-running-cost manufacturing of high bright vertical structured LED (V-LED)*2 but also achieves die separation (dicing), which supports the ultra-thinning and minimization of each device currently under development. The DFL7560L fully-automatic laser saw which supports this LLO technology will be on display at SEMICON Japan 2015 (held at Tokyo Big Sight, Dec. 16-18).
*1 Laser Lift-off: Detaching the material layer from the substrate by irradiating a laser on the material layer formed on the substrate.|
*2 Vertical structured LED (V-LED) and Lateral LED (please refer to the drawing on the right)
|The V-LED, which has been used for automotive headlamps and UV disinfection lamps, employs Laser Lift-off (LLO) in sapphire substrate detachment processes. The existing gas laser LLO requires frequent maintenance and improvements in processing quality. In response to those needs, we have developed an LLO which uses solid-state lasers and our own original optical system and the applicable model, and DFL7560L, the equipment which uses these technologies.
Employs a solid-state laser to save a significant amount of time (reducing the frequencies of replacing consumable products and adjusting optical axis), achieve a stable processing quality, and improve productivity.
- Employs a solid-state laser to save a significant amount of time (reducing the frequencies of replacing consumable products and adjusting optical axis), achieve a stable processing quality, and improve productivity.
- ₋ Employs our original optics system to process at an extensive focal range with optimal power. This suppresses wafer damage and minimizes detachment failures. In addition, the surface roughness after detachment becomes one-third of the current value.
(This video has been edited for the DISCO website)
Example of Applicable Processes
- Sapphire substrate detachment for V-LED*3
The light emitting layer is remounted on a highly exoergic conductive substrate for the purpose of improving brightness and preventing heat generation. The LLO is used in this sapphire substrate detachment process. This makes it possible to reduce damage to the light emitting layer, minimize detachment failure, and suppress brightness.
Process example of V-LED
- Die separation of an ultrathin wafer with backside metal, such as power devices (e.g. Si, SiC, and GaN)
Die thinning is required to improve power device performance. However, a metal layer is formed on the backside of a power device wafer, and the stress caused by the layer generates wafer warpage when grinding the wafer down to less than several dozens of microns. This also makes the subsequent process steps difficult.
Mounting a substrate such as glass on a wafer effectively suppresses this warpage. However, it has been difficult to detach the substrate after tape mounting using existing LLO processes because tape distortion occurs due to the heat generated by the laser. In response to this issue, DISCO’s LLO prevents heat generation by optimizing the laser’s, making it possible to detach ultrathin die from the substrate after tape mounting.
Example of processing an ultrathin power device
This also makes die separation for ultrathin wafers of less than 20 μm a reality.
This process is also expected to be used for other devices besides just power devices, such as mobile devices which require a low profile. (Patent pending)
The DFL7560L is installed in DISCO’s R&D center and in DISCO HI-TEC TAIWAN CO., LTD. We have been receiving test cut requests for processing prototype devices and materials other than V-LED.
*3 Precautions for the patent
If the laser lift off is performed for LED, please note that you might violate patent nos.4285776 in Japan, and US6071795 and US6420242 in other countries.