减小SiO_2光波导表面粗糙度的ICP干法刻蚀工艺研究

Improvement of ICP etching process for reducing the surface roughness of SiO_2 optical waveguides

波导表面粗糙度引起的散射损耗是SiO2光波导传输损耗的主要来源,通过降低表面粗糙度可以获得低损耗SiO2光波导。通过优化ICP干法刻蚀工艺的各参数(如温度、压强、气体流量、感应/偏置功率等)获得了低粗糙度的SiO2光波导,并采用SEM和AFM对刻蚀表面粗糙度进行了定量测试。采用优化刻蚀工艺可将表面粗糙度从35.4nm降低到3.6nm,波导传输损耗约为0.1dB/cm。

Scattering loss caused by surface roughness of waveguides is the main source of waveguide propagation loss. We can obtain a low loss optical waveguide by reducing the waveguide surface roughness. In this paper, all the parameters of the process of ICP etching, such as the temperature, the pressure in the chamber, the flow rate of reactive gases, the reactive/bias power are optimized to obtain SiOz optical waveguides with a small surface roughness. An atom force microscope with a high accuracy is used for the measurement of the surface roughness. A very small surface roughness of 3. 6nm is achieved under the optimal etching condition. The propagation loss of the fabricated SiO2 waveguide is about 0. 1dB/cm.