Daijitsu Harada

Shin-Etsu super-high-flat substrate for FPD panel photomask

Recently, high-resolution exposure machine has been developed for production of high-definition (HD) panels and higher-flat photomask substrates for FPD is being expected for panel makers to produce HD panels. In this report, we review the Shin-Etsu’s advanced technique of producing super-high-flat and shape-controlled large size photomask substrates that we reported the last PMJ 2017 a year ago and make a subsequent progress report thus far. Shin-Etsu has developed surface polishing and planarization technology of photomask substrates. Our most advanced IC Photomask substrates have gained the highest estimation and appreciation from our customers because of their excellent surface quality (non-defect surface without sub-0.1μm size defects) and ultimate flatness (sub-0.1μm order having achieved). By scaling up those IC photomask substrate technologies and developing unique large-size processing technologies, we have achieved creating high-flat large substrates, even G8.x-photomask and G10-photomask substrates as well as regular G6-G8 photomask substrates. The core technology is that the surface shape of the substrate is completely controlled by the numerical control system with height information inputs and the processing calculation. For example, we can regularly produce substrates with their flatness of 3μm or less for each size, measurement of which is carried out with high reliability tuned flatness tester. In addition, we can produce a substrate whose surface shape is arbitrary by using this core technology. It means we can deal with customers’ demanding shape or potentially necessary shape in the future to contribute to the soon-coming next generation FPD industries.