Abstract
The demand of high brightness and high power LED has increased over the past few decades. In industry, Pattern sapphire substrate (PSS) and nano-pattern sapphire substrate (NPSS) are the most common technique to increase the brightness and output power of LED. Therefore the technique of PSS and NPSS has been researched and developed. By patterning hexagonal 2D array on sapphire wafer in micro- or nano-scale, the output power of the LED can be highly improved. In industry, steppers are the most commonly used technique for pattern sapphire. However, as the technology evolved, 4 inch wafer has brought up some new issues in the stepper system. The total thickness variation of 4” sapphire wafer is around 20-30 um and the linewidth of the pattern is down to nano-scale. These issues are causing stepper less competitive in industry. This research provides a new approach, laser interference lithography (LIL), to fabricate PSS and NPSS. Yet, there are two ways to pattern hexagonal 2D array on sapphire by LIL. First is multi-exposure LIL (2-beam LIL with double exposures), and the second is multi-beam LIL (3-beam interference with single exposure). However, the throughput of these two types LIL has not to be revealed yet. This aim of this paper is to simulate and compare the advantages and the disadvantages of these two types of LIL.