The photometallic process is a new method of producing images in thin films of metals, semiconductors, and dielectrics. The process depends on the photogeneration of reactive material in situ which reacts with the thin film to produce a pattern.
A polymer layer containing a photodecomposable material is coated on a thin film. A pattern of light on the surface causes preferential photodecomposition and these products react with the thin film, removing it where exposed to light. The coating and reaction products are removed in a solvent rinse. A positive copy of the light image is thus obtained in the thin film. Since very close control of the photodecomposition is possible, images with continuous grey scale or various depths of reaction are possible. The process is exemplified by a description of the photoetching of gold, nichrome, and silicon dioxide. Other materials for which the process has been demonstrated are listed. A discussion of thin-film parameters, coating parameters, and proposed reaction mechanisms is presented. Among other applications, the process has potential use in microelectronic circuit fabrication.