LED assembly having maximum metal support for laser lift-off of growth substrate

US7736945B2 · kind B2 · utility

Assignees

• Philips Lumileds Lighting Company LLC · US
• KONINKLIJKE PHILIPS ELECTRONICS NV · NL

Inventors

• Stefano Schiaffino · Pleasanton, US
• Daniel A. Steigerwald · Cupertino, US
• Mari Holcomb · Rue de l'Église, US
• Grigoriy Basin · San Francisco, US
• Paul Scott Martin · Pleasanton, US
• John E. Epler · San Jose, US

Key dates

• Filing date: Dec 15, 2006
• Grant date: Jun 15, 2010
• Expiry date: Aug 8, 2028

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10H20/857

Abstract

Described is a process for forming an LED structure using a laser lift-off process to remove the growth substrate (e.g., sapphire) after the LED die is bonded to a submount. The underside of the LED die has formed on it anode and cathode electrodes that are substantially in the same plane, where the electrodes cover at least 85% of the back surface of the LED structure. The submount has a corresponding layout of anode and cathode electrodes substantially in the same plane. The LED die electrodes and submount electrodes are ultrasonically welded together such that virtually the entire surface of the LED die is supported by the electrodes and submount. Other bonding techniques may also be used. No underfill is used. The growth substrate, forming the top of the LED structure, is then removed from the LED layers using a laser lift-off process. The extremely high pressures created during the laser lift-off process do not damage the LED layers due to the large area support of the LED layers by the electrodes and submount.