Polishing time calculation method to reduce oxide-film-CMP send-ahead works

Abstract

In order to obtain higher throughput maintaining high precision in the CMP process, it is important to reduce send-ahead work and rework related to film thickness over the within-wafer distribution. This paper presents a new polishing time calculation method that ensures film thicknesses at all measurement positions satisfy the control limit, and gives a judgment on whether send-ahead work is necessary, with the margin of variation of film thicknesses from the control limits after CMP based on the within-wafer distribution of the removal rate and film thickness before CMP. The CMP-APC system applying these methods reduces the defects in film thickness after CMP, along with the amount of send-ahead work, which is half that of the former CMP-APC Run-to-Run control system.

CMP process run-to-run control to adjust margin in control limit

“…In order to achieve this condition, we have developed the even control limit polishing time calculation algorithm [8]. The CMP process model (1) is plugged into Eq.…”

Consumption Optimization in CMP Processes

“…The within-wafer removal rate distribution in a concentric fashion are monitored with APC to calculate the polishing time for the product wafers (7) and the monitoring events attached with the use time of the consumables are used to calculate the coefficients of the CMP process model (8) . Within-wafer removal rate trends can be observed using APC, as shown in Fig.…”