Abstract: Defining a new display photomask quality standard
In recent years, there has been a fast technological development within the display industry. AMOLED becomes the mainstream in premium electronics segment and further demand increase is expected by recent introduction of foldable products. Furthermore, 5G telecommunications will enable new content to be enjoyed on real high resolution displays such as 4k in smartphone, 8k TVs and even higher resolution in AR & VR.
These trends have rapidly tightened the lithography requirements for the photomasks. The top critical display photomask requirements are now reaching similar level as the 350nm node semiconductor mask. In order to overcome the challenges many of semiconductor technologies are transferred to the display industry such as RET (Resolution Enhancement Technology) which requires smaller feature size with finer CD control. Moreover, the display photomasks are typically 30 ~ 80 times larger than 6” reticle, thus it creates an extraordinary challenge to meet the requirements over the full area and with the stability needed for expose times which can be 24 ~ 48 hours. Hence, the demand increases for higher resolution with extremely stable lithography equipment for photomask manufacturing, which will benefit high-end panel manufacturing with maintained yield.
In this talk, Mycronic briefly discuss the challenges of leading edge photomask manufacturing and the correlation between photomask quality and display quality. In addition, share the achieved results from the latest mask writer technologies and demonstrate how high resolution writing with below than 40nm CD uniformity can be achieved on photomask larger than one square meter.