How to Eliminate or Minimize the Variation in Removal Rate Due to the Conditioner Age in Oxide CMP Processes

摘要

In a CMP manufacturing environment, the goal is to have zero reworks or incidents. However, the majority of Oxide CMP processes used throughout the semiconductor industry suffers from uniformity issues, a situation that can only be remedied by accurately identifying and eliminating all the various root-causes. In Oxide CMP, Phoenix manufacturing line uses home grown software called POWER CMP-2 (PCMP2), which using control charts, predicts the polish time based upon the estimated removal rate of a particular tool: the PCMP2 software was developed by the ST Crolles Research and Development Facility. If the actual removal rate drops significantly, the estimated removal rate deviates from the actual value resulting in wafer under polish. Removal rate data over multiple conditioner discs suggests that the disc life has a significant impact upon the actual removal rate. The objective of this study is to eliminate or minimize the removal rate variation due to the age of the conditioner disc.rnThis paper describes the benefits of conditioner disc change at different time intervals. Previously, all three discs were changed after every third pad change: the new procedure now involves changing only one disc at each pad change. In this way, one disc will always be new, with the other two discs being at one third and two thirds lifetime respectively. Such a procedure serves to average the disc lifetime by controlling the average and run to run removal rate variations due to disc ageing.