On Synchronization of Generic Lithography Machine Open-chains using a Novel Fine-Positioning Stage System

In this paper, we present an extension of our work on the characterization of lithography machines. So far, the machine was approximated using three open chains, reticle, optics and wafer chains, all sharing one common root. In general, the performance of the machine is assessed under partial or full synchronization among the chains being involved. The previously developed fine-positioning stage, or smart-material board, is utilized here to realize two types of synchronization, a partial one dealing with the synchronization error between the reticle and the wafer chains, specifically, and a modified synchronization which factors in all the chains motions. This stage provides additional degrees of freedom that can be used to regulate the tracking errors in a chain and to achieve partial or full synchronization as proposed herein without affecting the stability of the remaining stages. Therefore, in case an update is needed, the fine-positioning stage controller can be tuned either online or while the machine is at standstill. This feature of the fine-positioning stage makes it suitable as an add-on to exiting machines whose controllers' settings are preferred to be held constant with the possibility of increasing their performance. These advantages will be illustrated by a simulation example.