|Definition:|| micromachining that removes a part of the substrate
Note 1 to entry: An example of bulk micromachining is a processing method based on etching by a chemical solution to remove unnecessary parts of a substrate. Covering the areas to be preserved with a mask of SiO2 or Si3N4 ensures that etching cannot progress below the surface. Also, a boron-doped layer can stop the etching of the part below the surface layer. Recently, silicon fusion bonding has been used to fabricate still more complex structures.