空间天线用金属薄膜/有机材料结构脉冲激光刻蚀界面特性研究

Study on Pulse Laser Etched Interface Characteristics of Metal Thin Film/Organic Material Structures for Space Antennas

  • 摘要: 为了研究脉冲激光刻蚀过程中金属薄膜/有机材料界面的特性变化,以典型的有机材料聚酰亚胺(PolyImide,PI)为基底,通过物理气相沉积在其表面制备了1 µm厚的金属Cu薄膜,分别采用短脉冲(100 ns)和超短脉冲(290 fs)激光刻蚀去除部分金属薄膜,然后借助XPS、SEM等对刻蚀后的界面进行了表征分析,测试了样品高频段(4~18 GHz)的介电性能以及太阳光谱(200~2 000 nm)的透射性能。结果表明,纳秒和飞秒激光作用后,Cu/PI这种热物性相差很大的材料体系的界面特征存在共性和差异。共性体现在两种激光刻蚀后的介电常数和损耗因子值比刻蚀前均有小幅提升,这是由刻蚀过程中金属薄膜气化反向沉积的颗粒及界面处PI碳化在新表面上形成了一层很薄的介质薄膜引起的。差异性体现在界面微观形貌上,由于飞秒和纳秒激光的作用机制不同,飞秒激光刻蚀后界面浅表层形成了微孔洞结构,导致在500~2 000 nm可见/近红外波段透射率下降60%左右,而纳秒激光刻蚀后透射率没有明显变化。

     

    Abstract: To study the characteristic changes of metal film/organic material interface during pulsed laser etching, the 1 µm thick metal Cu film was prepared on the surface of typical organic material (Polyimide PI) by physical vapor deposition. Short pulse (100 ns) and ultra-short pulse (290 fs) laser were used to remove part of the metal film on the surface. XPS and SEM were used to characterize the etched interface. The dielectric properties of the samples in high frequency band(4 ~ 18 GHz) and solar transmission spectrum (200 ~ 2 000 nm)were tested. The results show that there are similarities and differences in the interface characteristics of Cu/PI, which is composed of materials with very different thermal properties, after nanosecond and femtosecond laser etching. The commonness is reflected in that the dielectric constant and loss factor values of the two kinds of samples are slightly higher than those before etching, which is caused by the particles of the metal film reverse deposition during the etching process and the carbonization of PI, a thin dielectric film formed on the new surface at the interface after etching. The difference is reflected in the microscopic morphology of the interface. Due to the difference in the etching mechanism of femtosecond and nanosecond laser, micro-structures are formed in the surface of the interface after femtosecond laser etching, resulting in a decrease of transmittance about 60% in the visible/near-infrared range from 500 to 2 000 nm, while the transmittance does not change significantly after nanosecond laser etching.

     

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