高斯分布激光散焦距离对激光转印Cu薄膜形貌影响及机理分析

Effect of Defocus Distance on Morphology of Gaussian Distributed Laser Induced Forward Transfer Cu Film and Mechanism Analysis

激光诱发前向转印(LIFT)技术作为微加工的一种手段,具有制备微小结构的能力,目前已经成为微细加工领域的研究热点。通过改变高斯分布的激光聚焦位置,进行了Cu薄膜在石英玻璃表面的转印实验,并对转印沉积薄膜进行了光学显微镜、扫描电子显微镜(SEM)和能量弥散X射线(EDX)等分析,探讨了激光散焦距离与沉积薄膜的尺寸、形貌以及厚度均匀性的关系,并在此基础上研究了转印薄膜形貌发生变化的机理。研究结果表明,随着激光光斑离焦距离的增大,转印图形的尺寸先增大后变小,直至消失。转印Cu薄膜的形态从环形或火山形,转变为圆形,并且圆形薄膜的边缘存在大量微小的Cu颗粒。薄膜的转印形式也由开始的液态转印向固态转印演变。

As a method of micro fabrication, laser induced forward transfer （LIFT） can be used to make microstructures. Presently, it has become a popular issue on microfabrication process. In this study, a Cu thin film is transferred from one quartz substrate to another quartz substrate by regulating the defocus distance of Gaussian distributed laser beam. The transferred Cu thin film is processed by optical microscope, scanning electron microscope （SEM）, and energy dispersive X-ray （EDX） analyzing. Relationship between defocus distance of the laser beam and size, morphology and uniformity of transferred Cu film is discussed. Moreover, mechanism of the morphology transition is analyzed based on the results. The results indicate that with the increase of defocus distance, the size of transferred Cu patterns increase firstly, then decrease, and disappear at last. Morphology of the transferred Cu patterns transforms from crater-shape to plane with many tiny Cu particles at the edge of the patterns. In addition, the transfer form of the thin film changes from liquid transfer to solid transfer.