APPARATUS AND METHODS WITH RESOLUTION ENHANCEMENT FEATURE FOR IMPROVING ACCURACY OF CONVERSION OF REQUIRED CHEMICAL MECHANICAL POLISHING PRESSURE TO FORCE TO BE APPLIED BY POLISHING HEAD TO WAFER

摘要

CMP systems and methods in which a polishing pad is moved relative to a wafer and a retainer ring implement instructions for applying required pressure to the wafer for CMP operations. Accuracy of computations of the pressures, and of conversion of the pressure to force, is improved without use of high resolution components, such as high resolution digital devices. Such improved accuracy is achieved using both digital and analog operations, and by converting values of required pressure or force from one set of units to a second set of units and then back to the first set of units. A quantization process is performed using data processed by average resolution digital devices. The process transfers both pressure/force scale and pressure/force set point data between separate processors to obtain computed values of pressure and force having acceptable accuracy, such that quantization errors are eliminated or significantly reduced.