Cluster tools are a type of widely used semiconductor manufacturing equipment. Generally, a cluster tool is operated on a built-in schedule; however, it is impossible to modify or change the built-in schedule because of the closed architecture of the scheduling system for the tool. In this study, we propose a framework for an open architecture scheduling system for a single-armed cluster tool with PM cleaning operations. The scheduling system works by scheduling command files that can be modified or replaced from outside. As an application of the framework, performance comparison analysis between the backward and backward(z) sequences in a singlearmed cluster tool with multi-period PM cleaning operations is conducted.