On the interaction between measurement strategy and control performance in semiconductor manufacturing

Manufacturing in the high revenue semiconductor industry involves a highly capital intensive process consisting of more than 300 steps. To ensure stable process operation and ultimately meet the exacting requirements on final product quality, the typical advanced IC fabrication process requires many on-line sensors and off-line metrology tools for acquiring process and product information necessary for effective monitoring and control. However, the high cost associated with these measurement devices has made the economics of metrology a major factor in the industry’s quest for world-class manufacturing. In this paper, we first introduce various measurement data types and describe how they feature within an ideal fab-wide control architecture; subsequently, and from a process control point of view, we derive various run-to-run controllers, carry out stability analyses, and analyze control system performance. These results are then applied to the problem of rational metrology strategy selection where the effects of various metrology strategies on control system performance are systematically analyzed. In particular, if control performance takes priority over economics, we present results for determining maximum tolerable sampling intervals, maximum tolerable delay, and measurement priority.