The invention provides a model-based control approach to
chemical-mechanical planarization (CMP) control. The preferred embodiment
comprises mathematical models of the CMP process. These models play a
critical role in obtaining superior control performance. Model-based
Control Design involves the construction of a dynamic mathematical model
of the system to be controlled, e.g. a removal rate model of a CMP
system. The model can then be evaluated via computer simulations, and
validated using data from the system. The invention provides a method and
apparatus that processes in-situ data from a suite of real-time sensors
and produces real-time commands to multiple actuators, such as applied
pressures, slurry-flow rate, and wafer/pad velocity. A key aspect of the
invention is an integrated model-based
pressure-temperature-velocity-slurry flow control system that includes
many innovations in real-time mode identification, real-time gain
estimation, and real-time control.