The Pre-Metal Dielectric (PMD) layer serves to physically and electrically isolate the front-end-of-line (FEOL) field-effect transistors from the upcoming middle-of-line (MOL) contact structures T1.The preceding PMD 3 CMP step achieves necessary global planarization to meet the strict depth-of-focus requirements for the subsequent Contact Photo step (Engineering Practice).This specific Post CMP Cleaning step is inserted immediately after planarization to eradicate residual slurry abrasives, shea