Polishing apparatus and polishing member dressing method
A dresser is enabled to adjust a swing speed in scanning areas set on a polishing member along a swing direction. A surface height of the polishing member in monitoring areas set in advance on the polishing member along the swing direction of the dresser is measured. A dress model matrix defined from the monitoring areas, the scanning areas and a dress model is created. Height profile predicted value is calculated using the dress model and the swing speed in each scanning area or a staying time. Evaluation index is set based on a difference from a target value of a height profile of the polishing member and a step of setting the swing speed in each scanning area of the dresser based on the evaluation index. At least one of parameters to determine the target value or the evaluation index of the height profile is made to change automatically.
1. A method for dressing a polishing member by causing a dresser to swing on the polishing member used for a polishing apparatus for a substrate, the dresser being enabled to adjust a swing speed in a plurality of scan areas set on the polishing member along a swing direction, the method comprising:
a step of measuring a surface height of the polishing member in a plurality of monitoring areas set in advance on the polishing member along the swing direction of the dresser;
a step of correcting the surface height of the polishing member based on a measurement interval of the surface height and an amount of fluctuation in a measured value of the surface height;
a step of creating a dress model matrix defined from the monitoring area, the scan area and a dress model;
a step of calculating a height profile predicted value using the dress model and the swing speed in each scan area or a staying time;
a step of setting an evaluation index based on a difference from a target value of a height profile of the polishing member; and
a step of setting the swing speed in each scan area of the dresser based on the evaluation index.
2. The method according to claim 1 , wherein the step of correcting is performed when the measurement interval of the surface height exceeds a reference value and when the amount of fluctuation in the measured value of the surface height exceeds a threshold.
3. The method according to claim 2 , wherein the threshold when the measured value of the surface height increases and the threshold when the measured value of the surface height decreases have different values.
4. The method according to claim 1 , wherein in the step of correcting, the amount of fluctuation in the measured value of the surface height is added to or subtracted from the measured value of the surface height for a past certain period.
5. A polishing apparatus that polishes a substrate placed on and in slidable contact with a polishing member, comprising:
a dresser that dresses the polishing member by swinging on the polishing member, a swing speed of which is adjustable in a plurality of scan areas set on the polishing member along a swing direction;
a height detection section that measures a surface height of the polishing member in a plurality of monitoring areas set in advance on the polishing member along the swing direction of the dresser;
a height correction section that corrects the surface height of the polishing member based on a measurement interval of the surface height and an amount of fluctuation in the measured value of the surface height;
a dress model matrix creation section that creates a dress model matrix defined from a plurality of monitoring areas, scan areas and dress models;
an evaluation index creation section that calculates a height profile predicted value using the dress model and the swing speed in each scan area or a staying time and sets an evaluation index based on a difference from a target value of a height profile of the polishing member; and
a moving speed calculation section that calculates the swing speed in each scan area of the dresser based on the evaluation index.