Yasutaka Ban

Title: Yasutaka Ban: Innovator in Photomask Technology

Introduction

Yasutaka Ban is a prominent inventor based in Yokohama, Japan. He has made significant contributions to the field of photomask technology, holding a total of 4 patents. His work focuses on advancements that enhance the efficiency and effectiveness of photolithographic processes.

Latest Patents

One of his latest patents is related to the fabrication of photomasks. This innovation allows for the creation of a photomask for ultraviolet light with a contrast of 10 or larger. The process involves generating a color center by irradiating a calcium fluoride crystal substrate with a KrF excimer laser. This laser operates at a wavelength of 248 nm and an energy of 10 J/cm². The original photomask is formed by a chromium film on a quartz substrate, and a pattern is created by a color center that corresponds to the original photomask pattern. Additionally, a similar photomask can be fabricated using X-rays with wavelengths ranging from 0.5 to 1.0 nm, utilizing a gold film on a silicon substrate.

Another notable patent is for a reticle used in photolithographic patterning. This reticle comprises a substrate that is transparent to an optical beam, along with an opaque layer that interrupts the optical beam according to a desired pattern. The opaque layer is patterned to form both opaque and transparent patterns, allowing selective transmission of the optical beam. Furthermore, a phase shift pattern, which is transparent to the optical beam, is included to cancel diffraction effects.

Career Highlights

Yasutaka Ban is currently employed at Fujitsu Corporation, where he continues to innovate in the field of photomask technology. His work has been instrumental in advancing the capabilities of photolithography, which is crucial for semiconductor manufacturing.

Collaborations

Throughout his career, Yasutaka has collaborated with notable colleagues, including Kazuo Tokitomo and Kenji Sugishima. These collaborations have contributed to the development of cutting-edge technologies in the industry.

Conclusion

Yasutaka Ban is a key figure in the realm of photomask technology, with a focus on innovations that enhance photolithographic processes. His contributions through patents and collaborations have significantly impacted the semiconductor industry.