PMD 1 Etch represents the critical dielectric removal phase within the Pre-Metal Dielectric (PMD) contact module, sequentially following the PMD 3 and PMD 2 etch steps P2.The primary objective of this process is to anisotropically etch the remaining thick oxide layer down to the underlying Contact Etch Stop Layer (CESL) P2.By defining the vertical pathways through the insulating dielectric, this step physically prepares the structure for the subsequent CESL etches and eventual metal interconnect