  Photolithography control system (PCS) is an extremely complex distributed
control system, which is composed of dozens of networked microprocessors,
hundreds of actuators, hundreds of thousands of sensors, and millions of lines
of code. Cyber-physical system (CPS), which deeply merges computation with
physical processes together, copes with complex system from a higher level of
abstraction. PCS is a representative CPS. This work points out that thinking
under the framework of CPS, which includes holistic perspective, model-based
design, hardware/software co-design and continuous integration, could solve the
issues presented in the current PCS. Although the traditional embedded system
approach and the CPS approach would be coexisting in the PCS for a long time,
the CPS approach is definitely the future of the PCS development.
