Development of phase-shift masks to meet the market demand for high resolution

In recent years, LTPS-OLED panels have become more popular in the smartphone market, the adoption of LTPO-OLEDs has increased, and the market demand for higher resolution and lower power consumption of FPD panels is also increasing. In addition, OLED panels are beginning to be applied to IT products such as notebooks, and the investments to the larger 8th Generation has been planned by panel makers. We, SKE Group, have been developing Phase Shift Masks to achieve high resolution in collaboration with each lithography machine manufacturer for years in order to meet the further market demand as a specialist in the manufacturing of large photomasks in Japan. We'll introduce our latest activities this time. One is the development of DUV Phase Shift Mask specialized for exposure with a shorter exposure wavelength in order to solve both high resolution and stability of DOF (Depth of Focus). Also, that can withstand mass production. The other is a Phase Shift Mask with a higher transmittance and a phase reversal function. Conventional Phase Shift Masks generally exhibit a phase reversal function with a transmittance of around 5%, It has been found that a higher transmittance PSM (HR-PSM in SKE) contributes to the stability of DOF in order to achieve the target line width in fine pattern exposure near the exposure limit. We will also introduce the latest photomask development.