Company Filing History:
Years Active: 2012-2014
Title: Innovations of Robert L Hsieh in LED Fabrication
Introduction
Robert L Hsieh is a notable inventor based in Los Altos, California. He has made significant contributions to the field of LED fabrication, holding a total of four patents. His work focuses on improving the efficiency and effectiveness of LED technologies through innovative photolithographic methods.
Latest Patents
One of Hsieh's latest patents is titled "Photolithographic LED fabrication using phase-shift mask." This invention discloses methods for forming a roughened surface for an LED to enhance light emission efficiency. The process involves photolithographically imaging a phase-shift mask pattern onto a photoresist layer, resulting in a periodic array of photoresist features. The roughened substrate surface is created by processing the exposed photoresist layer, which leads to the formation of a periodic array of substrate posts. These posts serve as scatter sites that improve LED light emission efficiency compared to LEDs without a roughened surface. The use of a phase-shift mask allows for affordable photolithographic imaging suitable for non-flat LED substrates while providing the necessary resolution to form the substrate posts.
Another significant patent by Hsieh is related to "Optical alignment systems for forming LEDs having a rough surface." This alignment system is designed for aligning a wafer during the lithographic fabrication of LEDs. It includes a wafer with a roughened alignment mark and a lens that superimposes an image