Krishna P. Murella

Exploring CMP solutions to planarity challenges with tungsten plugs

Abstract Tungsten plugs have been used in the recent past for local interconnects and for level–level interconnect applications. The resist etch back process has been the method of choice historically for planarization purposes. However, with the advent of chemical mechanical polishing (CMP) technology, one has an alternate path for achieving global planarity. Process integration issues have to be worked out. In this paper, we have explored the effect of various process parameters and consumable changes on planarity/non-uniformity. The across wafer and wafer–wafer non-uniformity 1-sigma was reduced from 10–20% to 5000 A/min with 5.5% wafer–wafer removal variation.

Copper post-CMP cleaning process on a dry-in/dry-out tool

Metal Chemical Mechanical Planarization (CMP) and post CMP cleaning have continued to increase in importance in semiconductor manufacturing. The introduction of copper metallization into semiconductor manufacturing processes has created a need for integrating CMP and cleaning tools, as well as a demand for the development of novel cleaning solutions. One system designed for integrated CMP processing and cleaning, commonly referred to as dry-in/dry-out CMP, is the SpeedFam Auriga C. The Auriga C integrates a widely used polishing tool together with a proven cleaning technique. The key to the operation of the Auriga C cleaning process is the effective operation of the PVA brush cleaners, water track transport, final jet rinse and high-speed spinner dryer. The effective operation of the cleaning mechanism for copper post- CMP cleaning requires the use of new chemical solutions. Typical solutions used for post process cleaning of more mature CMP processes are either ineffective for cleaning or chemically incompatible with the copper process. This paper discusses the cleaning mechanism used in an integrated dry- in/dry-out tool and demonstrates an effective and novel cleaning solution for use with this type of post-CMP cleaning process.