多层介质薄膜膜层间界面粗糙度及光散射

Interface roughness of multilayer dielectric optical thin film

利用泰勒霍普森相关相干表面轮廓粗糙度仪(Talysurf CCI)分别对基底和采用电子束热蒸发技术沉积的15层二氧化钛(TiO2)和二氧化硅(SiO2)为膜料的介质高反膜的膜层间的界面粗糙度进行了研究,并对不同工艺下沉积的薄膜界面粗糙度以及不同基底粗糙度上沉积的薄膜的表面粗糙度进行了比较。实验结果表明:TiO2薄膜对基底或下表面粗糙度有较好的平滑作用,随着TiO2和SiO2膜层的交替镀制,膜层间表面粗糙度呈现出低高交替的现象,随着膜层层数的增加,膜层间界面粗糙度低高变化范围减小;采用离子束辅助沉积工艺时,膜层间界面粗糙度低高变化范围较小。总散射损耗的理论计算表明:中心波长处完全非相关模型下的总散射损耗小于完全相关模型下的总散射损耗。实验结果表明:界面粗糙度的相关度约为0.4。

Interface roughness between the substrate and high-reflecting dielectric fill, which consisted of 15 alternative layers of TiO2 and SiO2 and was deposited with electron beam evaporation, was measured with Taylor Honson coherence correlation interferometer （Talysurf CCI）. The interface roughness of films deposited with different processes and the surface roughness of fills deposited on the substrates with different roughness were compared, respectively. Experimental results show that TiO2 thin fill has smoothing effect to the roughness of substrate or below interface. With alternative deposition of TiO2 and SiO2 thin film, the interface roughness are in low-high alternation, the range of the low-high alternation of interface roughness diminishes as the layer number of thin film increases. However, while the multilayer film deposited with IBAD, this range hardly decreases. The theory calculation of total scattering losses show that total scattering loss of the uncorrelation model of interface roughness at central wavelength is lower than that of its full correlation model. Experimental results show that the correlation degree of interface roughness is about 0.4.