May 5, 2011
High-speed laser scanning forms periodic nano-trenches on silicon
Researchers from Kanagawa Industrial Technology Center, Tokyo Institute of Technology and Phoeton Corporation are busy developing high-throughput nanofabrication techniques and looking at the mechanisms that underpin the processes in more detail.
Following an experiment to optimize annealing conditions on a silicon substrate by CW laser irradiation, the scientists found asymmetric sheet resistance on the surface of the wafer. After studying the surface to look for the reasons, the team located bumpy nanostructures.
The researchers introduced a high-speed scanning CW laser as a versatile approach to building up these self-organized nanostructures along the trace of a scanning laser. The scanning CW laser extends the irradiated spot over the whole area of the target, and carves periodic nanostrip grating lines (nano-SGL) along the trace of a single scanning laser beam at a speed of 300 m/min, while a femtosecond laser irradiating a target forms a periodic structure in the irradiated spot typically after hundreds of laser shots.
Although the structure formed by a femtosecond laser is called a grating structure, it is rather a fibre-like structure; it has granularity, relief, ripples or grooves with some periodic structure.
As an example of the versatility of this method, a computer cooling fan was used for rotating the target sample to draw concentric circles, resulting in structural colour from the formed nano-SGL, as shown in the photo above.
Additional information can be found in the journal Nanotechnology.
About the author
The study was conducted under the enterprise support act at Kanagawa Prefectural Government. Dr Satoru Kaneko is a chief researcher at Kanagawa Industrial Technology Center (KITC) and a special research fellow at Tokyo Institute of Technology. The members of KITC are Dr Takeshi Ito, Dr Kensuke Akiyama, Dr Manabu Yasui, Dr Chihiro Kato, Dr Satomi Tanaka and Dr Yasuo Hirabayashi. Akira Matsuno is a director of Phoeton Corp. and Takashi Nire is the president of Phoeton Corp. Associate professor Hiroshi Funakubo and Prof. Mamoru Yoshimoto are based at Tokyo Institute of Technology.