The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 05, 2014
Filed:
Dec. 21, 2010
Andrew M. Hawryluk, Los Altos, CA (US);
Robert L. Hsieh, Los Altos, CA (US);
Warren W. Flack, San Jose, CA (US);
Andrew M. Hawryluk, Los Altos, CA (US);
Robert L. Hsieh, Los Altos, CA (US);
Warren W. Flack, San Jose, CA (US);
Ultratech, Inc., San Jose, CA (US);
Abstract
Photolithographic methods of forming a roughened surface for an LED to improve LED light emission efficiency are disclosed. The methods include photolithographically imaging a phase-shift mask pattern onto a photoresist layer of a substrate to form therein a periodic array of photoresist features. The roughened substrate surface is created by processing the exposed photoresist layer to form a periodic array of substrate posts in the substrate surface. A p-n junction multilayer structure is then formed atop the roughened substrate surface to form the LED. The periodic array of substrate posts serve as scatter sites that improve the LED light emission efficiency as compared to the LED having no roughened substrate surface. The use of the phase-shift mask enables the use of affordable photolithographic imaging at a depth of focus suitable for non-flat LED substrates while also providing the needed resolution to form the substrate posts.