高斯分布激光前向转印Cu薄膜形貌及机理

Morphology and Mechanism of Gaussian Distributed Laser Induced Forward Transfer Cu Film

激光诱发前向转印技术,作为一种微加工手段,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。通过改变高斯分布激光脉冲功率密度,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X射线光电子能谱(XPS)表面氧化状态分析,探讨了激光脉冲功率密度与沉积薄膜的尺寸、特殊形貌以及薄膜厚度均匀性的关系,并在此基础上研究了激光转印Cu薄膜的机理。结果表明,当激光平均脉冲功率密度达到1×105 W/cm2时,Cu薄膜的转印才可以发生。随着激光脉冲功率密度的增加,转印Cu薄膜尺寸增加,并由薄膜转变为圆环形,最终尺寸达到一定值。激光转印薄膜表层10nm以下,基本上没有氧化发生。薄膜附着在基板上,连接紧密,并未观察到明显的扩散迹象。

As a method of micro fabrication, laser induced forward transfer （LIFT） technology can be used to make microstructures. Presently, the fabrication process has become a popular issue in the field of micro-machining. A Cu thin film is transferred from one quartz substrate to another quartz substrate by regulating the pulse power density of Gaussian distributed laser beam. The transferred Cu thin film is characterized by optical microscopy, scanning electron microscopy （SEM）, and X-ray photoelectron microscopy （XPS） analysis. The relationship between pulse power density of laser beam and size, special morphology and uniformity of transferred Cu film is discussed, and the oxidation condition of the transferred Cu film is also studied. Moreover, the mechanism of the transferred process is analyzed based on the results. It is found that the Cu film transfer process can be realized when the average pulse power density of laser beam reaches 1x10^5 W/cm2. With the increase of pulse power density of laser beam, the size of transferred Cu film is also enlarged, and reaches a certain value at last with the morphology transforming from plane to crater-shape. Almost no oxidation phenomenon is observed on the Cu when transferred Cu film is sputtered off 10 nm in thickness. The transferred film adheres well to the target substrate, and no obvious diffusion phenomenon is observed between Cu film and the target quartz substrate.