Micro-machining of single-crystal materials

Single-crystal silicon is increasingly being used to produce new, ultra-miniaturized mechanical devices. This article describes some of the techniques used to produce such structures: chemical machining, dry etching, electrochemical etching, epitaxy, sealing...

Micro-machining (of crystalline or non-crystalline materials) is based on collective manufacturing techniques, which have enabled the advent of integrated circuit chips by making them very inexpensive. Chips are produced simultaneously, which spreads the cost of manufacture between all the parts.

During the manufacturing stages of silicon integrated circuits, technologists were led to use etching processes that could lead to the creation of three-dimensional shapes such as cavities, holes, pyramids, grooves, hemispheres, overhanging beams, membranes... Subsequently, other, more complex etching techniques were developed.

This principle of machining very small shapes or with very high precision is not limited to silicon, but can be applied to other substrates (quartz, germanium, gallium arsenide...). However, silicon remains the main material used, thanks to the accumulated knowledge gained from integrated circuit manufacturing technologies.