Wet etching of cusp structures for field-emission devices

The use of wet chemical etching to produce sharp tip structures for field-emission device applications is investigated by considering the etching of silicon in potassium hydroxide and nitric/acetic/hydrofluoric acid etchants. The basic theory of etch front propagation is presented. This theoretical description is used, with experimentally determined etch rates, to obtain a complete phenomenological description of both etch systems. The accuracy of this description is illustrated by comparison of theoretical and experimental tip shapes. Guided by this, the general features of such etching processes are highlighted with specific reference to their application in producing accurate field-emission tip structures.