Nano imprint lithography technology can improve the luminous efficiency of 20-30% LED

Nanoimprint lithography is a technique for transferring a large number of patterns by pressing a mold with a fine pattern on the substrate and the like. Recently, more and more practical cases of the technology.

Mass production of LED mold with R2R

The fine patterning technique using nano imprint technique is helpful to improve the luminous efficiency of LED and organic EL. Toshiba has developed a technology that includes a dedicated imprint device that will increase the luminous efficiency of the LED by 20 to 30%. Using the "PSS" (Patterned Sapphire Substrate, patterned sapphire substrate) formed on the surface of the sapphire substrate, the reflectivity is improved, and the output of the light is improved.

Toshiba Deputy business mechanical nano machining system business minister Gotou Hiroshi said, there is the problem of how to reduce the number of defects of die, and how to make use of existing cost pattern than stepping device has more advantage. If the substrate is defective, LED will not shine. In order to reduce the cost of repeated use of the mold, then the defects will be more and more".

The company's response to these two problems is to use the R2R method to copy a large number of resin mold made disposable products. The 4 inch wafer cost less than $5 goal has taken shape". Another advantage is that the resin mold, which is not suitable for flat sapphire substrate.

High quality GaN crystal

Recently, the possibility of further improving the efficiency of LED by nano imprint lithography is also presented. Laboratory of ancient river mechanical metal, Jinze Industrial University, associate professor at the Waseda University, Mizuno Jun and Toshiba machine using nanoimprint technology developed GaN crystal defects (dislocation dislocation: crystal containing. The dislocation density of GaN crystal is more than 1 * 109/c square meters, is considered to be the reason for a decrease in luminous efficiency to LED through current. ) down to about 1% of the original method.

The specific methods are as follows: firstly, the SiO2 film is formed on the original GaN crystal, and dozens of nm wide small openings are formed by nano imprint technique, and then the GaN crystal is grown again. In this way, the dislocation of the GaN crystal below the SiO2 film will not reach the GaN crystal above, which can reduce the dislocation of the GaN crystal. Professor of water, Waseda University, said, we have produced LED, confirmed that the technology can improve the output power and extend the life. Should also be used for power semiconductors".

Water wild, said the technology is also expected to reduce the driving voltage of LED. "Because of the small number of dislocations, the GaN crystals, which had to be 140 m thick, can be thinned down to less than 21 m".