Micro-OLED显示斜纹Mura的研究及改善

硅基微显示(Micro-OLED)工艺中,在进行驱动线路制备时,需进行化学机械研磨(CMP)处理,保证金属互联层的稳定性及均一性。不同材料对CMP工艺的耐受性存在差别,切割道或净空区通常为介电材料层(SiO、SiNx等绝缘层),较金属膜层区域更易受CMP磨损,经过多次CMP制程后段差累积加深。在进行Spin涂胶工艺时,段差区偏大(>1μm)会引起涂胶、显影后的关键尺寸(CD)差异过大,造成斜纹Mura显示不良。验证发现,调试不同曝光能量与CD均一性无明显相关性;Spin涂胶转速调整对显影后CD均一性有一定改善,但效果有限,无法完全改善。胶厚0.8~2.5μm验证中,当Spin涂覆胶厚大于2.0μm时,能有效减弱涂胶过程的飞溅效应,斜纹Mura的发生率降低到0%。作为根本防止措施,可在切割道或Dummy区域设计与CMP当层相同的Dummy Pattern,提升CMP工艺制程均一性,从而确保斜纹Mura发生率小于0%。

In the silicon-based Micro-OLED process,chemical mechanical polishing(CMP)treatment is needed to ensure the stability and uniformity of the metal interconnection layer during the preparation of the driving circuit.The resistance of different materials to CMP process is different.The cutting path or clearance area is usually dielectric layer(SiO,SiNx and other insulating layers),which is more vulnerable to CMP wear than metal film.After many CMP processes,the cumulative difference deepens.In the Spin glue coating process,the large segment difference area(greater than 1μm)will lead to excessive difference in critical size(CD)after glue coating and development,resulting in poor twill Mura display.It is found that there is no significant correlation between the adjustment of different exposure energy and CD uniformity;the adjustment of Spin coating speed can improve the CD uniformity after development to some extent,but the effect is limited and can not be improved completely.In the glue thickness of 0.8~2.5μm verification,when the Spin coating glue thickness is greater than 2.0μm,it can effectively reduce the spatter effect in the glue coating process,and the incidence of twill Mura is reduced to 0%.As a fundamental preventive measure,the same Dummy Pattern as the CMP layer can be designed in the cutting path or Dummy area to improve the uniformity of the CMP process,thus ensuring that the incidence of twill Mura is less than 0%.