Towards Microstructures with Ultrahigh Aspect-Ratio and Verticality in Deep Silicon Etching

Devices containing deep silicon trenches with higher aspect ratio and higher verticality could achieve better performance, such as higher carrier mobility in trench gate field effect transistors, lower on-resistance in power switching devices, larger capacitance in silicon capacitors, and so on. In this work, we demonstrate a deep silicon trench structure with aspect ratio of >65, depth of >100 µm and high perpendicularity of 90°±0.1°. This is realized through optimization of the process recipe, which could control the balance between deposition and etching. The high aspect ratio silicon trench with high verticality has significance to advancing the field of silicon device fabrication.