The Performance and Dimension Control of Copper Alloy for Etching Applications

摘要

As the microelectronic devices are becoming lighter in weight, thinner, shorter, and smaller in dimensions, the line width and line space of the lead frames become narrower and the layout becomes more complex. These developments impose great challenges to the etching technologies in both processing and precision control. Since copper alloys have gained wide applications in the microelectronics industry, a study of the etching properties of copper alloys should be of great value. We have developed a new copper alloy of high mechanical strength and high electrical conductivity. This alloy has also excellent etching properties and can be used in lead frames and other related microelectronic products. CuCl resistant films were found to form at the surfaces during etching of the copper alloy in a FeCl_3 solution. By controlling the growth of the CuCl film, the etching rate can be controlled to obtain a high accuracy in dimension control. A relationship between the dimensions and the etching process was established and a database was built. This database contains systematic processing parameters relating to the line width, line space, and the layout geometry as well as side undercut and product dimensions. Using these results, the selection of etching procedures for new devices is much simplified and the appearance and dimension control are greatly improved.