Patent ID: 9306122
Filing Date: 2016-04-05
CPC Classification: H01L

Claim Text:
1. A method for manufacturing an LED comprising: forming successively an LED die and a second electrode on a substrate, wherein the substrate is sapphire; patterning a back surface of the substrate to form inverted trapezoidal contact holes which expose the LED die; and filling the contact holes with conductive material until the back face of the substrate is covered by the conductive material; wherein patterning a back surface of the substrate to form inverted trapezoidal contact holes which expose the LED die comprises: forming a hard mask on the back face of the substrate, wherein the hard mask is silicon dioxide; performing an anisotropic etching to the upper surface of the sapphire substrate with a mixed solution of sulfuric acid and phosphoric acid using the hard mask as an etching mask to form a plurality of inverted trapezoidal contact holes until the LED die is exposed; and removing the hard mask with a hydrofluoric acid solution.