Polishing method and polishing apparatus
According to one embodiment, a polishing method comprises pressing a substrate being rotated against a polishing pad being rotated and supplying slurry on the polishing pad, measuring a surface temperature of the polishing pad, and when the surface temperature is not less than a predetermined temperature, jetting jet stream containing supercooled droplets from a nozzle having a narrow portion toward the polishing pad.
1. A polishing method comprising:
pressing a substrate being rotated against a polishing pad being rotated, and supplying slurry on the polishing pad;
measuring a surface temperature of the polishing pad; and
jetting jet stream containing supercooled droplets which have a temperature lower than a freezing point of the droplets, from a nozzle whose flow path includes a first portion having a first cross-sectional area, a second portion having a second cross-sectional area, and a narrow portion located between the first and second portions and having a third cross-sectional area smaller than the first and second cross-sectional areas toward the polishing pad, when the surface temperature of the polishing pad is not less than a predetermined temperature.
2. The polishing method according to claim 1 , further comprising adjusting flow rate of air supplied to the nozzle so that the surface temperature falls within a predetermined range.
3. The polishing method according to claim 1 , wherein the predetermined temperature is determined by a thermal decomposition temperature of a complex-forming agent and an oxidizing agent contained in the slurry.
4. The polishing method according to claim 1 , wherein the supercooled droplets contain organic acid or surfactant reacted with residues on the polishing pad.
5. The polishing method according to claim 1 , wherein compressed air with a pressure of not less than 300 kPa and a flow rate of not less than 200 NL/min and water with a flow rate of not more than 100 ml/min are supplied to the nozzle to jet the jet stream.
6. The polishing method according to claim 1 , wherein the nozzle is a Laval nozzle.
7. The polishing method according to claim 1 , wherein in the nozzle, the nozzle diameter is expanded downstream from the throat portion.
8. The polishing method according to claim 1 , wherein the time for the surface temperature to reach the predetermined temperature is calculated based on a relationship between a rotation speed of the polishing pad and a variation with time of the surface temperature, and after a lapse of the calculated time from the start of the rotation of the polishing pad, the jet stream is jetted from the nozzle.
9. The polishing method according to claim 1 , wherein the jet stream is jetted on the downstream side in the rotational direction of the polishing pad.
10. A polishing apparatus comprising:
a holding unit configured to hold a substrate rotatably and vertically movably;
a polishing table rotatably provided below the holding unit and having a polishing pad applied onto an upper surface of the polishing table;
a supply unit configured to supply slurry on the polishing pad;
a temperature sensor configured to measure a surface temperature of the polishing pad; and
a nozzle whose flow path includes a first portion having a first cross-sectional area, a second portion having a second cross-sectional area, and a narrow portion located between the first and second portions and having a third cross-sectional area smaller than the first and second cross-sectional areas, and configured to jet jet stream containing supercooled droplets which have a temperature lower than a freezing point of the droplets toward the polishing pad when the surface temperature measured by the temperature sensor is not less than a predetermined temperature.
11. The polishing apparatus according to claim 10 , wherein the predetermined temperature is determined by a thermal decomposition temperature of a complex-forming agent and an oxidizing agent contained in the slurry.
12. The polishing apparatus according to claim 10 , wherein the supercooled droplets contain an organic acid or a surfactant reacted with residues on the polishing pad.
13. The polishing apparatus according to claim 10 , wherein the nozzle is provided adjacent to the downstream side in the rotational direction of the polishing table of the holding unit.
14. The polishing apparatus according to claim 10 , wherein the nozzle jets the jet stream into a region of the polishing pad in contact with the substrate.
15. The polishing apparatus according to claim 10 , wherein the nozzle is a Laval nozzle.
16. The polishing apparatus according to claim 10 , wherein in the nozzle, the nozzle diameter is expanded downstream from the throat portion.
17. The polishing apparatus according to claim 10 , further comprising a control unit adjusting flow rate of air supplied to the nozzle so that the surface temperature falls within a predetermined range.
18. The polishing apparatus according to claim 10 , wherein the nozzle is provided adjacent to the holding unit.
19. The polishing apparatus according to claim 10 , wherein a plurality of the nozzles are linearly arranged from the center of the polishing table toward the outer peripheral direction.
20. The polishing apparatus according to claim 10 , wherein a plurality of the nozzles are arranged in a circular pattern.