Etch planarization - A new approach to correct non-uniformity post chemical mechanical polishing

摘要

The introduction of 3D devices and new materials at sub 28 nm nodes presents challenges for within-wafer and wafer-to-wafer CMP thickness uniformity control that are critical for device yield and performance. Upon CMP the typical thin film uniformity across the whole wafer is unable to meet the target of less than 2 nm 3σ variation. Furthermore, wafer-to-wafer uniformity variation requires a wafer by wafer approach to uniformity correction. In this work, a novel etch planarization approach is presented that combines a conventional production-proven etch process that is temperature sensitive on an inductively coupled plasma reactor with die level thermal controlled electrostatic chuck (ESC). Improved process control enables cost effective uniformity improvements in excess of 85%. In addition, the approach provides wafer-to-wafer tuning capabilities.