Polishing-amount simulation method for buffing, and buffing apparatus
The invention simulates polishing amount taking into account pressure concentration that occurs in the vicinity of the edge of a substrate when a small-diameter buffing pad overhangs the substrate to be buffed. One embodiment of the invention provides a method for simulating polishing amount in a case where a polishing pad of a smaller size than a substrate is used to buff the substrate. The method includes measuring distributions of pressure that is applied from the polishing pad to the substrate according to each overhang amount of the polishing pad relative to the substrate by using a pressure sensor, and correcting the pressure that is used in the polishing amount simulation in accordance with the overhang amounts and the measured pressure distributions.
1. A method for simulating polishing amount in a case where a polishing pad of a smaller size than a substrate is used to buff the substrate, the method including:
measuring distributions of pressure that is applied from the polishing pad to the substrate according to each overhang amount of the polishing pad relative to the substrate by using a pressure sensor;
quantifying the measured distributions of the pressure applied to the substrate with respect to the each overhang amount of the polishing pad relative to the substrate;
one-dimensionalizing the quantified pressure distributions with respect to the each overhang amount along a radial direction of the substrate;
summing the one-dimensionalized pressure distributions of the each overhang amount in the radial direction of the substrate;
determining a pressure correction value by dividing the sum of the one-dimensionalized pressure distributions of the polishing pad in the each radial position of the substrate by a distance of the polishing pad on the substrate; and
correcting the pressure that is used in the polishing amount simulation in accordance with the overhang amounts and the measured pressure distributions.
2. The simulation method of claim 1 , further comprising: simulating polishing amount in a case where a part of the polishing pad oscillates over the substrate during buffing.
3. The simulation method of claim 2 , wherein:
the polishing amount is calculated using the determined pressure correction value.
4. The simulation method of claim 2 , further comprising:
calculating a buffing condition that is required to achieve a given target polishing amount.
5. The simulation method of claim 4 , wherein:
the buffing condition to be calculated is oscillation velocity of the polishing pad.