锗表面二维亚波长结构的反应离子刻蚀制备

Two dimensional subwavelength structures on Ge surface fabricated with reactive ion etching

为了获得具有金字塔结构的二维亚波长结构表面,提高其高宽比,用掩模曝光光刻及反应离子刻蚀技术,以SF6和O2为反应气体,在Ge衬底上制备了二维亚波长结构.用扫描电镜对刻蚀图形的形貌进行了观察,研究了功率、气压、气体流量及掩模图形对刻蚀图形的影响.结果表明:刻蚀图形腰部被优先刻蚀,形成凹陷的侧壁轮廓;O2流量增大有利于在侧壁形成保护层,从而减小腰部刻蚀、增大顶部及根部刻蚀;功率及气压过大或过小均会使侧壁刻蚀较大;方形图案比圆形图案掩模更有利于刻蚀出深度较大的亚波长结构.

To achieve subwavelength structured surface with pyramid profile and improve the aspect ratio, masked lithography and reactive ion etch （RIE） were employed to fabricate subwavelength structures （SWSs） On Ge surfaces with SF6 and 02 as the reactive gases. Scanning electron microscopy （SEM） was used to characterize the morphologies of the etched patterns. Influences of 02 flow rate, gas pressure, power and the mask pattern geometry on the morphology of the etched pattern were investigated. The results show that the waist part of the patterns are preferentially etched resulting in a concave sidewall profile. The rise in 02 flow rate facilitates the formation of passivation film on the sidewall, which reduces the etch of the sidewall and increases the etch of the top part and bottom part of the pattern. Too low and too high power and gas pressure all lead to a intense etch of the waist part of the structure. Square pattern mask is preferable over circular pattern mask for deep etch of the SWSs.