With micro powder blasting techniques structures on depth or through wafer structures in silicon and glass can be fabricated. Besides dry etching and wet etching micro powder blasting is another method to create structures in substrates. Micro sandblasting, as it is called as well, is mainly used for lab-on-a-chip resp. micro fluidic applications not for MEMS devices.
Micropowder blasting is a pure physical process. The sand removes part of the base material using high pressure / velocity. The material is ablated only there where the glass or silicon is not protected by the structured layer of resist.
This resist layer is aligned to the existing structures on the wafer, so that a high-precision positioning to the existing structures is guaranteed. The removed material is sucked off during the process, so that the glass resp. silicon is not damaged.