ChromaLift™ Laser Lift-Off (LLO)
Laser LED Lift-Off
For high power blue LEDs, GaN (gallium nitride) or InGaN (indium gallium nitride) semiconductor material is grown on a sapphire substrate. To remove or ‘Lift-Off’ the semiconductor from the sapphire, a high intensity laser beam is directed through the sapphire and aimed at the GaN. This creates a shockwave at the interface disassociating the GaN from the Sapphire.
An excimer laser is employed due to its high pulse energy, typically 1J/cm2 on target with large area illumination, 1mm2-5mm2. The LLO process is also used on LED wafers with AlN (aluminum nitride) and AlGaN materials.
JPSA’s technical team has over 20 years experience in the design and implementation of excimer lasers and beam delivery systems. Furthermore, JPSA has patents issued and patents pending on the LLO technique as well as proprietary capabilities for optimal yield.
The process creates free-standing GaN films and integrates GaN LEDs onto virtually any substrate. Additionally, this technique increases LED light output and has low operating costs due to high throughput capability whereby multiple die are exposed by a single pulse.
The basic concept behind UV LLO is the different absorption of UV light by GaN and sapphire. GaN, with a bandgap of ~3.4eV, strongly absorbs 248nm radiation (5eV), while sapphire is a poor UV absorber due to its high bandgap energy (9.9eV). The laser light goes through the back of a sapphire wafer, causing photo-induced decomposition at the GaN/sapphire interface, and creating a localized explosive pressure that debonds the interface.
Innovative beam homogenization and synchronized high-speed stage motion-laser triggering (“fire-on-the-fly”) techniques-allow high-yield LED LLO at ambient temperature, with running times shorter than 1 min/2 inch diameter wafer. The same technique is also used for AlN lift-off, OLEDs and for transferring other thin films.
JPSA Laser’s revolutionary IX-Series Excimer Laser Systems are industrial-grade LED Lift-off systems for the compound semiconductor and wafer fab industries.
Using special wafers, the sapphire growth substrate may be reused, and the cost of LED fabrication can be reduced. Additionally, this approach is fast, delivering increased LED light output and is vital in the manufacture of the new class of high brightness LEDs.
The system includes PC-controlled power meters and beam profilometers, enclosed in a laser safe Class 1 system, industrial-grade reliability with R&D flexibility. Additionally, the system is programmed and controlled via user-friendly JPSA Controls32 Software.
- Stress-free die liftoff over large area
- Operates at low ambient temperatures
- Step & repeat or “fire on the fly” mode
- Micron accuracy patterning and stitching
- Ultra-uniform homogenized beam & adjustable FOV
- PC-controlled power meters and beam profilometers
- Doubles as lithographic system and dry-etching GaN
- Industrial grade reliability
- User-friendly software
- Higher light output; lower leakage current
News and Events
JPSA Laser provides excimer and Diode Pumped Solid State (DPSS) laser micromachining solutions for:
- Thin film PV patterning
- Laser scribing
- LED Lift-Off (LLO)
- Laser dicing
- Silicon edge isolation
- Ink-jet nozzles
- Microfluidic devices
- Micro vias
- Annealing and doping
- Parylene ablation
- Concentrator photovoltaics
See JPSA at:
EU PVSEC
Feria Valencia, Spain
Septemeber 6-9
Booth L3/H4/A29
