Influence of inner shell electron on material processing by soft X-ray free electron laser

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K12494
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 80040:Quantum beam science-related
• Research Institution: The University of Tokyo
• Principal Investigator: Sakaue Kazuyuki 東京大学, 大学院工学系研究科(工学部), 准教授 (80546333)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 軟X線レーザー / レーザー加工 / 光・物質相互作用

Outline of Final Research Achievements

In this project, we worked on processing using a soft x-ray laser, which enables direct laser processing more precisely than conventional lasers. Since the photon energy of the laser light is 10 times higher than that of conventional laser light, the physical process of the processing was investigated. Laser direct micro-processing on the sub-micrometer scale was achieved on various targets such as silicon, sapphire, and diamond. As a processing mechanism, it was confirmed that the effect of absorption by inner-shell electrons determines the structure of the material after laser irradiation and that the processing mechanism on the material surface differs depending on the relationship between the photoionization energy and the binding energy. These achievements open up soft X-ray processing as a new laser processing.

Free Research Field

量子ビーム科学

Academic Significance and Societal Importance of the Research Achievements

本研究課題における上記の成果は、軟X線レーザーによる加工の原理をすべて理解するにはもちろん至らないものの、その一部を明らかにした。従来のレーザーでは到達困難なサブマイクロメートルスケールの直接微細加工を実現し、見出した軟X線レーザー加工のユニークな特徴は、今後より微細化が進むレーザー加工技術開発において、重要な知見となる。これらの成果より次世代のレーザー直接微細加工の基盤を確立することができたといえる。今後もこの基盤を活用し、軟X線レーザーによる加工のメカニズムに関する研究や特徴的な加工の抽出に取り組んでいく。