Development of new micromachining technology by laser microfabrication technique

近年来，利用光聚合物的立体光刻技术进行激光微加工已成为一个备受关注的课题，因为它能够制造出真正的三维微结构，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。包括半导体集成电路技术在内的仅适用于二维结构的传统技术在这方面遇到了严重的困难。为了开发满足真正三维加工的新型微加工技术，我们提出了由皮秒脉冲激光器和光学显微镜组成的单光子吸收激光微加工系统的立体光刻工艺，并探索了光固化树脂光聚合制备微观结构的方法。将放置在显微镜台上两片玻璃板之间的紫外光固化树脂（Nopcocure 800）用355nm激光脉冲（-30 ps, 10Hz）在1秒内照射，观察到在激光束焦点光斑附近形成树脂。聚焦的激光脉冲在底部玻璃板上进一步照射，形成了一种具有1 μ m形成分辨率的棒状树脂。制备方法的分辨率与激光强度密切相关，采用原子力显微镜测定。在Z方向上逐层制备了50 μ m × 10 μ m × 10 μ m的步长为0.5 μ m的矩形管。为了验证结构制造的空间选择能力，在两个较宽的侧壁之间制造了一根杆。通过扫描电镜图像验证了制备的成功。实际上，利用现有的制造技术，可以毫无困难地制造出大纵横比的微结构。

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.