Enhancing the analysis of variance (ANOVA) technique with graphical analysis and its application to wafer processing equipment

One of the critical steps required to improve the overall quality of a wafer manufacturing operation is a reduction in the variability of the individual processing operations. As a result, there is an increasing need to quantify the capabilities of semiconductor manufacturing equipment. The goal should be to design a consistent method of monitoring equipment performance that samples the major sources of variation that can impact the process output. This paper discusses a statistical method that utilizes multi vari analysis and the analysis of variance to achieve this goal. The data presented is taken from a commercially available silicon epitaxial reactor and FTIR film measurement tool, but the technique is generic and applicable to other wafer processing operations. The analysis method is presented along with some examples of the application of the calculated standard deviation and process variation. In addition to determining the performance of a piece of equipment over time, this method of analysis can be used to specify and qualify equipment. As an extension of this analysis it is possible to determine the contribution of the measurement system to the observed variability in the process output