9. Yield Analysis and Quality Assurance and Control Methods Used in Microsystems Manufacturing

This chapter covers the importance of ensuring quality and reviews methods for performing yield analysis in microsystems manufacturing. Methods for determining device functional and parametric yields are both reviewed. The types of defects that result in nonfunctional devices and various analytical techniques used for functional yield modeling based on point defects are explained. Parametric yield is then reviewed wherein a manufacturing function that incorporates all of the statistical distributions of the parameters describing the microsystems device’s output response is overlaid by an acceptance region to determine the yield. Methods to ensure quality during manufacturing using statistical process control (SPC) are covered. Control charts are used to show how processing steps can be monitored for whether they are in control or not. Process capability is shown to be an excellent gauge for whether a manufacturing process is able to produce devices having acceptable yields. Lastly, techniques for sampling of the measurements on wafers during and after manufacturing so as to obtain data that is rationally subgrouped so as to identify non-random changes are discussed.