High density aluminum etcher process window characterization and comparison

The process characteristics of four, high density, aluminum, plasma etchers using three types of plasma sources have been experimentally studied. Aluminum etch rate was found to depend mainly on process pressure, total flow rate, chamber volume, and chlorine flow rate. In addition, when etching with a BCl3/Cl2 chemistry, aluminum line profile appears to be comparable between plasma sources. Electrical breakdown on a IC capacitor, aluminum line critical dimensions, and aluminum and photoresist etch rate uniformities were found to differ between etcher types. Since etch rate uniformities and aluminum line critical dimensions appear to be determined by ion current flux, chamber design and process parameters, and similar ion current flux values and process parameters can be obtained with different plasma sources, it is suggested that the plasma source has limited affect on these characteristics. Only breakdown voltage appears to depend on the plasma source.