Feedback control using detection of clearance and adjustment for uniform topography

摘要

A method of controlling polishing includes storing a desired ratio representing a ratio for a clearance time of a first zone of a substrate to a clearance time of a second zone of the substrate. During polishing of a first substrate, an overlying layer is monitored, a sequence of measurements is generated, and the measurements are sorted a first group associated with the first zone of the substrate and a second group associated with the second zone on the substrate. A first time and a second time at which the overlying layer is cleared is determined based on the measurements from the first group and the second group, respectively. At least one adjusted polishing pressure is calculated for the first zone based on a first pressure applied in the first zone during polishing the first substrate, the first time, the second time, and the desired ratio.

主权项

1. A method of controlling polishing, comprising:
prior to polishing of a first substrate, storing a desired ratio, the desired ratio representing a desired ratio determined prior to polishing of a substrate for a clearance time of a first zone of the substrate to a clearance time of a second zone of the substrate, and wherein the desired ratio indicates that the clearance time of the first zone differs from the clearance time of the second zone; polishing the first substrate, wherein the first substrate has an overlying layer on an underlying layer or layer structure; during polishing of the first substrate, monitoring the overlying layer with an in-situ monitoring system and generating a sequence of measurements from the in-situ monitoring system; sorting the measurements into a first group associated with the first zone of the first substrate and a second group associated with the second zone on the first substrate; determining a first time at which the overlying layer is cleared from the first zone on the first substrate based on the measurements from the first group; determining a second time at which the overlying layer is cleared from the second zone on the first substrate based on the measurements from the second group; calculating at least one adjusted polishing pressure for the first zone based on a first pressure applied in the first zone during polishing the first substrate, the first time, the second time, and the desired ratio; and polishing a second substrate using the at least one adjusted polishing pressure for the first zone, the adjusted polishing pressure being such that a ratio of a clearance time of the first zone of the second substrate to a clearance time of the second zone of the second substrate is closer to the desired ratio than without such adjustment, and such that the desired ratio provides a difference between the clearance time of the first zone of the second substrate and the clearance time of the second zone of the second substrate.