Fabrication of Highly Ordered Silicon Nanowire Arrays With Controllable Sidewall Profiles for Achieving Low-Surface Reflection

A novel and simple approach is demonstrated for fabricating silicon nanowire arrays (SNWAs) with controllable sidewall profiles. A single-step deep-reactive-ion etching (SDRIE) is used to transfer the holography patterned photoresist template to silicon or silicon-on-insulator substrates. With the SDRIE etching process, scalloping of the sidewalls can be avoided while reserving the high-mask selectivity over resist and high-etching rate. The sidewall angle of resultant patterns can be adjusted by tuning the composition of the gas mixture of the process. A modified-SDRIE process with a linearly changed gas flow is further developed to extend its capability. A post-high-energy argon plasma treatment is used to create sharp tips on the top of SNWAs and to increase the filling factor. Broadband antireflective (AR) window with a low reflectivity can be realized from tall SNWAs with high-filling factor. Depositing silicon dioxide over SNWAs can further enhance the AR performance. The position and bandwidth of the AR window can be controlled by tuning the SNWA parameters.