Improvements in edge polishing control through advances in carrier head technology

摘要

The recent economic downturn has caused increasing attention to increasing the yield of die at the wafer edge to improve total revenue from manufacturing devices on 200-mm wafers. For device layers requiring Chemical Mechanical Polishing (CMP) this attention has targeted the carrier head as the strongest toggle that influences the edge polish and using clever carrier head designs makes meeting these requirements practical. In this work we have carried out a study of an Ebara Carrier Head employing the Ebara Technologies, Inc. EPO-222 CMP tool to help identify carrier head possibilities on meeting the above stated goals. It will be shown that by using this advance carrier head that we are able to control the edge polish profile. Comparing 2-mm edge exclusion diameter scans we will show that toggling of the edge polish can result in under and over polishing of the wafer edge as well as flat and stable polishing. These results are shown in Figure 5, which shows data using a 121-point @ 2mmEE diameter scan and 49-point @ 3-mm EE polar map. As can be seen the WIWNU is below 2.5-% for both scan types, with a correspondingly high polish rate ≥35OO-A/min. Finally in this paper we will define the process window regime in which this advance carrier head functions well.