Bosch Process

a patented plasma etch process whereby the etcher chemistry is switched every few seconds back and forth between etching and polymerizing chemistries. The Bosch process is commonly used to produce high rate anisotropic trench etching of silicon. During the etch chemistry step, rapid isotropic etching of the silicon occurs. During the polymerizing chemistry portion of the process all exposed surfaces of the substrate are coated with polymer. During the next etch chemistry portion of the process, ion bombardment removes the polymer from the bottom of the trench normal to the direction of ion motion, and a isotropically etched cavity is then created. The Bosch process results in microscopic "scallops" on the trench sidewalls being etched. The degree of sidewall scalloping may be controlled by varying the length of each etch - polymer deposition cycle. See also, inductively coupled plasma.