A study of plasma-based copper etching reaction process.

摘要

A novel copper plasma etching method has been discovered and studied. Instead of forming volatile compounds during the plasma processing, copper was converted into a solution soluble product accumulated on the substrate surface. The reaction product was subsequently removed with a dilute hydrochloric solution. The results show that a copper thin film can be etched into a vertical profile at a high rate using this method with a parallel-plate reactor under mild conditions. The key factor for the success of this process is the copper-swelling phenomenon due to the plasma-copper reaction. The reaction product is a rough, porous and crystalline copper compound. Influences of parameters, such as plasma exposure time, pressure, plasma power, substrate temperature and reactive and additive gases (HCl, Cl₂, HBr, Ar, N₂, CF₄ , and O₂) on the reaction process were explored. In addition to morphology and the reaction rate, the relationship between the structure of the reaction product and the process conditions was investigated. Both plasma chemistry and ion bombardment play critical roles in the process. A reaction process model that describes the progress of the reaction through the copper layer was developed. In summary, copper film patterns can be effectively etched with this method. This method is applicable to many microelectronic, optoelectronic, display and storage devices.