RATE MONITOR FOR CHEMICAL ETCHING OF COPPER-FILMS

Etching copper layers to yield reproducible fine line patterns is an e ssential operation in conventional hybrid circuit or printed circuit b oard fabrication. The etch rate is commonly monitored by the amount of copper etched from a copper layer with a known thickness, and it requ ires many thickness measurements to obtain the desired accuracy, A nov el simple-to-use visual rate monitor has been developed for the copper etching operation, and it can be fabricated from inexpensive commerci ally available equipment in a straightforward manner, The etch rate me asurement time is reduced to the residence time of the monitor in the etcher.