Influence of AlSiTi grain boundaries on the plasma etch rate

The influence of the microstructure of an AlSiTi alloy on plasma etch rate is presented in this work. Metal films were individually sputtered onto silicon wafer substrates using different deposition conditions based on a design-of-experiments approach. The grain structure was analyzed for each metal film extracting the average grain size and the grain-size standard deviation. It was found that the etch rate increases with increasing average grain size and grain size standard deviation. Although grain size and standard deviation are dependent on each other in this experiment, we could show that the etch rate varies independently for each grain structure parameter. The physical mechanism at the base of this phenomenon deals with the different composition of grains and grain boundaries. Impurities and minority alloying materials segregate in grain boundaries, which are etched more slowly. A general approach to model the etch rate was performed calculating a factor which includes the total grain boundary leng...