Fine Striae Forming by Laser Beam Irradiation

本研究的目的是对玻璃和聚酰亚胺进行几何表面改性。首先，改变入射角、能量密度和脉冲数目，将ArF准分子激光照射到合成石英玻璃上。随着入射角的增大，出现了平行于辐射方向的条纹。特别是当角度大于80时，条纹沿辐射方向排列。当入射角大于83时，表面看不到条纹，入射角度对排列有很大影响。形成条纹的阈值注量为4J/cm2。从AFM观察，条纹的长度为15 mm，深度为130 nm，宽度为1.5 mm。此外，为了探讨钠钙玻璃的形成机理，从晶体结构或193 nm光的低吸收比角度选择了石英、刚玉和氟化钙，并对它们进行了相同的辐照方式。只有在石英上才出现了类似的条纹。这些结果表明，较低的吸收率和SiO_2组分容易形成细小的条纹。其次，用同样的方法对聚酰亚胺进行辐照。加工出了4个与玻璃表面相似的典型几何表面。为了评估这些表面对LG显示器液晶取向的适用性，制备了一个单元。结果表明，液态晶体是定向生长的。然后将本研究得到的表面应用于电气设备。

The aim of this research is the geometrical surface modification of glass and polyimide. First varying the incident angle, the fluence and the number of pulses, ArF excimer laser beam was irradiated on to a synthetic silica glass. As the incident angle increased, striae parallel to the radiation direction appeared. Particularly when the angle was larger than 80 , the striae lined up in the direction of radiation. However when the angle larger than 83 , no striae could be found on the surface.As the results, incident angle extremely effects the lining up. Threshold fluence to form striae was 4J/cm2. From the observation by AFM, the length, the depth and the width of a stria were 15mm ; l30nm, 1.5mm, respectively. Moreover to examine the formation mechanism soda-lime glass, quartz, corundum and calcium fluoride were chosen from the viewpoint of crystal structure or low absorption ratio of 193nm light, and they were irradiated on the same way. Only on the quartz similar striae appeared. These results draw the conclusion that the low absorption ratio and Si02 composition easily form fine striae.Secondly thin polyimide was irradiated on the same way. 4 typical geometrical surfaces similar to those on glass were produced. To estimate the applicability of these surfaces to the liquid crystal orientation of LG display, a cell unit was prepared. As the result, liquid cry-stal was confirmed to be oriented. Then the surface obtained in this research will be applied to electrical equipment.