The present invention relates to a method for removing a first dielectric layer of a semiconductor wafer. The first dielectric layer is formed on the surface of a second dielectric layer of the semiconductor wafer. The method comprises performing a chemical mechanical polishing (CMP) process on the first dielectric layer to remove a predetermined thickness of the first dielectric layer, measuring the remaining thickness of the first dielectric layer, providing an etching table having a plurality of thickness ranges of the remaining first dielectric layer and corresponding etching back procedure or parameters of each of the thickness ranges, and performing an etching back process to horizontally remove the remaining first dielectric layer according to the etching back procedure or parameters of the thickness range corresponding to the measured thickness of the remaining first dielectric layer.