Development of new micromachining technology by laser microfabrication technique

近年来，光致聚合物激光光固化快速成型技术因其能够快速成型真实的三维微结构而受到广泛关注，在新型微机械、集成微流体传感器和光电子器件等领域具有广阔的应用前景。传统的微加工技术，包括只适用于二维结构的半导体集成电路技术，在这方面遇到了严重的困难。为了满足真实的三维加工，提出了利用皮秒脉冲激光器和光学显微镜组成的激光微加工系统进行单光子吸收过程的立体光刻，并探索了利用光固化树脂的光致聚合来制造微结构。当放置在显微镜载物台上的两个玻璃板之间的紫外光固化树脂（Nopcocure 800）在1秒内用355 nm激光脉冲（~ 30 ps，10 Hz）照射时，观察到在激光束的焦点附近形成树脂。聚焦激光脉冲在底部玻璃板上的进一步照射导致形成具有1 μ m形成分辨率的棒状树脂。制造方法的分辨率强烈依赖于激光强度，并由原子力显微镜确定。并且我们成功地制造了50 μ m × 10 μ m × 10 μ m的矩形管，在Z方向上逐层制造，步长为0.5 μ m。为了验证结构制作的空间选择能力，在两个较宽的侧壁之间制作了一个杆。SEM图像证实了制备的成功。实际上，具有较大的深宽比的微结构已被制造没有原则上的困难，由目前的制造技术。

In recent years laser microfabrication utilizing stereolithography of photopolymers have been a subject of considerable interest for their ability to fabricate real three-dimentional microstructures which exhibit prospective applications on the fields such as new types of micromachine, integrated microfluid sensor and photoelectronic devices and so forth, on which conventional techniques including semiconductor IC technology suitable only for two dimensional structures have met severe difficulties.To develop new micromachining technique satisfying real three-dimensional fabrication, we proposed stereolithography of one photon absorption process by laser microfabrication system consisting of a picosecond pulsed laser and an optical microscope, and explored that fabrication of microstructure by photopolymerization of a light curing resin. WHen the ultra violet light curing resin (Nopcocure 800) placed between two glass plates on the microscope stage was irradiated with 355nm laser pulses (-30 ps, 10Hz) within a second, a formation of resin in the vicinity of the focal spot of the laser beam was observed. Further irradiation of the focused laser pulses on the bottom glass plate resulted in a formation of a rod-shaped resin with 1 mum formation resolution. The resolution of the fabrication methodology was strongly dependent on the laser intensity and was determined by atomic force microscope. And we succeeded fabrication of a rectangular tube of 50 mum x 10 mum x 10 mum was fabricated layr by layr in Z direction with step length 0.5 mum. To testify the the spatial selection capability of structure fabrication, a rod was fabricated between the two broader sidewall. The success of fabrication was approved from SEM image. Actually, microstructures with larger aspect ratio have been fabricated without principle difficulty by the present fabrication technique.