A Novel Method of Removing Sapphire for Solid-state Lighting Power GaN LEDs
20080201 - 20090930
Dr Enboa Wu
• Deliverable 1 - GaN wafers with sapphire removed and replaced with a new metal substrate: Wafer Size: Full Wafer (2-inch diameter) Sapphire Removal Percentage: 100% Wafer Number: 10 wafers • Deliverable 2 - LED prototypes: No. of packaged LEDs: 30 Chip Size: 1 mm x 1mm Wall plug efficiency improvement: 15% (over flip-chip LEDs) Drive Current: 350, 700, 1500 mA Forward Voltage at 350 mA: < 3.7 V Leakage Current at -5 V: < 5 uA Reliability: light output power drop < 15% after 1000-hour operation at 350 mA at 50C
Advanced Packaging Technology Ltd. Century Epitech City University of Hong Kong Epistar Corporation Jeng Yueh Enterprise Corp Kinik Company Nanofilm Technologies International Pte. Ltd Nathional Chiao Tung University Rohm and Haas Electronic Materials The Chinese University of Hong Kong The Hong Kong University of Science and Technology The University of Hong Kong Well Expediting Enterprise Corp.
The R&D project aims to develop a novel technology for the fabrication of power GaN LED chips, different from current laser liftoff method that causes patent concerns for most companies. It will develop a key technology to remove the sapphire substrate from the wafer and fabricate power LED chips with new metal substrate. GaN LEDs generate light in different colors: green (G), blue (B), purple/violet, ultraviolet, and white. Current GaN LEDs use sapphire as the substrate. Sapphire is an insulator and not a good thermal conductor, fundamentally limiting the power capability of such LEDs. This bottleneck will be eliminated by replacing sapphire with a new substrate in this proposed project. We will work closely with Hong Kong universities and industry, as well as other companies in greater China area. There is no company in China (including Hong Kong) that is in mass production of power white LED chips. The technology to be developed in this project will be transferred to the industry to upgrade their technologies and reduce the cost and increase the throughput for power LEDs. While ASTRI’s LED Program is strong in LED packaging and applications, this project will help ASTRI to establish a strong LED chip design and fabrication team, enhancing ASTRI’s overall LED technology strength.