Development status of High OD photo resist for CF black matrix

Recent years, resin Black Matrix (BM) for color filter (CF) of LCD have been produced at Optical Density (OD) 4.0/micron. However, making the higher luminance backlight is required because of the display fineness improvement. And the BM with higher OD targeting over OD4.0/micron is desired to prevent light leakage through BM film. In addition, higher sensitivity BM resist development is important to get higher throughput at larger size mother glass applications. But above two requirements is in trade-off relationship because BM resist has to react with very weak light through the BM film. BM resist development is faced on two major technical issues. The first is optical leakage through the CF film with the higher luminance backlights application in LCD to achieve display fineness. And the other is film upsurge at the intersection of BM and RGB film. It is difficult to maintain the uniformity of liquid crystal distribution in the pixel by the lack of uniformity of BM and RGB film and it is one of route cause of optical leakage. There are two solutions to prevent these problems. One is thick film applications of current OD resist with taper shape profile at the intersection with RGB film. It is effective solution to minimize the upsurge of RGB film, but BM film thickness at taper shaped area becomes thinner at the tip of BM film structure. Therefore it is difficult to prevent optical leakage completely with current OD resist. On the other hand, thinner film application with higher OD BM resist, the second solution, is applicable to prevent both the RGB film upsurge and optical leakage issue. The technical keyword of the second solution is the development of BM resist with higher OD and higher sensitivity than current resist. In this paper, we discuss the development of resin BM resists and resist pattern generation for these two technical solutions. In the resist development, we will report the high sensitivity BM resist with 4.0/micron and higher OD for thinner film application.