High aspect ratio micro-machining (HARM) is similar to surface micro-machining in that the desired structure is built upon the surface of the substrate. However, film thickness are typically on the order of $100 \mu m$ and vertical to lateral aspect ratios are on the order of 100 : 1.Further more, many HARM techniques are meant to be extended to molding processes so that relatively expensive micromachined molds can be used to create in expensive injection molded parts.

LIGA, non silicon based technology for high aspect ratio:

fabrication steps in LIGA process: