Fundamental study on nanoremoval processing method for microplastic structures using photocatalyzed oxidation

Microplastic structures, typified by photoresists for semiconductor devices or various MEMS devices, photosensitive resins of microstereolithography, and so on, play one of the most important roles in microdevice manufacturing. In order to process finer plastic structures with higher reliability for more complexly modulated microdevices in the next-generation micromanufacturing field, it is necessary to develop a nanoremoval processing method that can be applied to a corrective machining process with a removal resolution of less than 10 nm in both the lateral and vertical directions. In this paper, we propose a novel nanoremoval processing method for microplastic structures using photocatalyzed oxidation. Here, we use photocatalyst microparticles as an effective, specially designed material removal tool tip. Since light energy is not directly used for processing the material, the material removal resolution does not depend on the diffraction limit. Further, using photocatalysts eliminates microtool wear problems. In order to verify the fundamental feasibility of the proposed method focusing on the vertical resolution, we carried out basic experiments using TiO2 microparticles with a diameter of 500 rim on a cured photosensitive resin surface. AFM observation of the processed surface showed that a vertical removal resolution of 8 nm was achieved.