Polishing apparatus and polishing method

1. A polishing apparatus comprising:

a polishing table for holding a polishing pad having a polishing surface;

a motor configured to drive said polishing table;

a holding mechanism configured to hold a substrate having an object material to be polished and to press the substrate against the polishing surface, the object material belonging to one of a plurality of levels of a multi-level interconnect structure;

a dresser configured to dress the polishing surface; and

a monitoring unit configured to monitor a removal amount of the object material, said monitoring unit being operable to calculate the removal amount of the object material by quantifying a level number to which the object material belongs using a model equation containing a variable representing an integrated value of a torque current of said motor when polishing the object material, a variable representing a cumulative operating time of said dresser, and variables representing the level number to which the object material belongs and by substituting the cumulative operating time of said dresser and the integrated value of the torque current of said motor when polishing the object material into the model equation.

2. The polishing apparatus according to claim 1 ,

wherein the object material comprises a film.

3. The polishing apparatus according to claim 2 , wherein the level number is a level number of a group including plural levels having structures similar to each other.

4. The polishing apparatus according to claim 2 , wherein the model equation is a multiple regression equation created from a multiple regression analysis on data including removal amounts of the object material on plural substrates polished, integrated values of the torque current, cumulative operating times of said dresser, and level numbers.

5. A method for polishing a substrate comprising:

creating a model equation for calculating a removal amount of an object material to be polished on the substrate, the object material belonging to one of a plurality of levels of a multi-level interconnect structure,

the model equation containing a variable representing an integrated value of a torque current of a motor, a variable representing a cumulative operating time of a dresser, and variables representing a level number to which the object material belongs,

wherein the motor is configured to drive a polishing table for holding a polishing pad having a polishing surface, and

wherein the dresser is configured to dress the polishing surface;

polishing the object material by bringing the object material into sliding contact with the polishing surface; and

calculating the removal amount of the object material by quantifying the level number to which the object material belongs using the model equation and by substituting the cumulative operating time of the dresser and the integrated value of the torque current of the motor when polishing the object material into the model equation.

6. The method according to claim 5 , further comprising:

stopping said polishing of the object material when the removal amount calculated reaches a preset target value.

7. The method according to claim 5 ,

wherein the object material comprises a film.

8. The method according to claim 7 , wherein the level number is a level number of a group including plural levels having structures similar to each other.

9. The method according to claim 7 , wherein the model equation is a multiple regression equation created from a multiple regression analysis on data including removal amounts of the object material on plural substrates polished, integrated values of the torque current, cumulative operating times of the dresser, and level numbers.