CMP: Consideration of Stop-on Selectivity in Advanced Node Semiconductor Manufacturing Technology

Abstract

In advanced node semiconductor manufacturing, Chemical Mechanical Polish (CMP) is a critical integration step to many modules, from fin formation, replacement metal gate (RMG), to interconnects. In each application, CMP’s stop-on capability is increasingly seen as an essential element in gauging device integrity, and thus is critical to the successful implementation of a technology. Traditionally, CMP selectivity is merely a characteristic of slurry chemistry and its abrasive materials, and is measured by blanket rates of the corresponding films. However, in advanced node semiconductor manufacturing, as feature sizes are at Nano scale and polishing precision needs to be controlled at angstrom level, this slurry selectivity does not necessarily translate to a good stop-on capability. At this precision level, stop-on performance is sensitive to the selection of CMP pad as well as how the CMP process is developed. It is also highly sensitive to the integration process, including the deposition process and various integration steps leading to CMP. This presentation reviews the critical roles CMP plays in fin formation, replacement metal gate (RMG) and local interconnects. Taking middle of line (MOL) CMP steps as examples, detailed discussion will be presented on how selectivity is modulated and how the needs of stop-on capability is balanced with the need to make sure complete clearing.