Innovative electrochemical deep etching technique involving aluminum thermomigration

Abstract

A novel micro-machining technique for silicon deep anisotropic etching and isolating porous silicon structure formation is developed in this paper. This method combines aluminum thermomigration through a N type silicon wafer and silicon electrochemical etching in a HF-based solution. Using this technique, high aspect ratio trenches (1:5) and porous silicon isolating regions have been achieved through the entire thickness of the silicon wafers. Etch rate measurements have been performed varying the anodization current density. A maximum value of 22 µm.min -1 has been obtained. Moreover, the porosity behavior with the current density increase is also discussed.

Porous silicon for electrical isolation in radio frequency devices: A review

“…In the latter configuration, the backside contact is ensured by the electrolyte. 13 From an industrial point of view, only double tank cells can be used to achieve anodization on high area wafers (6 or 8 in. in diameter) considering the large volume of aid solution required in this case (more than 5 L).…”