Abstract: An improved CMP controller allows the calculation of the polish time required for removing a patterned layer stack to a desired final thickness, wherein the initial layer thickness of each layer contained in the layer stack is employed. Moreover, a topography factor characterizing the surface structure of the layer stack and a selectivity characterizing the ratio of removal rates between adjacent material layers are used. Furthermore, a state variable of the controller represented by the removal rate of one of the layers may periodically be updated on the basis of the previously calculated polish time and a measurement value of the finally obtained layer thickness. The improved controller is particularly advantageous in the CMP process for STI isolation structures, in which the final thickness of a CMP stop layer, having a significantly reduced removal rate compared to the overlying dielectric layer, has to be precisely controlled.