Method for estimating polishing profile or polishing amount, polishing method and polishing apparatus
A polishing method can automatically reset polishing conditions according to a state of a polishing member based on data on a polishing profile changing with time, thereby extending life of the polishing member and obtaining flatness of a polished surface with higher accuracy. The polishing method, includes steps of: independently applying a desired pressure by each of pressing portions of a top ring on a polishing object; estimating a polishing profile of the polishing object based on set pressure values, and calculating a recommended polishing pressure value so that a difference between the polishing profile of the polishing object after it is polished under certain polishing conditions and a desired polishing profile becomes smaller; and polishing the polishing object with the recommended polishing pressure value.
1. A polishing apparatus comprising:
a top ring for holding an object to be polished and rotating the object while pressing a front surface of the object against a polishing surface, said top ring having at least two pressing portions each capable of independently applying a desired pressure on a back surface of the object,
wherein, when a desired polishing profile of the object is set and an estimated polishing profile of the object is determined based on set pressure values, with a recommended polishing pressure value being calculated so that a difference between the desired polishing profile and the estimated polishing profile becomes within a predetermined range, said top ring is to press the front surface of the object against the polishing surface so as to polish the object under a polishing condition including the recommended polishing pressure value.
2. The polishing apparatus according to claim 1 , wherein
when an actual polished profile is measured after the object is polished and corrected pressure values are calculated based on a difference between the actual polished profile and the estimated polishing profile, said top ring is to press the front surface of a next object against the polishing surface so as to polish the next object under a polishing condition including a polishing pressure value based on the corrected pressure values.
3. The polishing apparatus according to claim 1 , wherein
when an actual polished profile is measured in a predetermined interval and corrected pressure valves are calculated based on a difference between the actual polished profile and the estimated polishing profile, said top ring is to press the front surface of a next object against the polishing surface so as to polish the next object under a polishing condition including a polishing pressure value based on the corrected pressure values.
4. The polishing apparatus according to claim 1 , wherein
when an actual polished profile is measured after the object is polished and corrected pressure values are calculated based on a difference between the actual polished profile and the estimated polishing profile, said top ring is to press the front surface of a next object against the polishing surface so as to polish the next object under a polishing condition including a polishing pressure value based on the corrected pressure values when a difference between the actual polished profile and the desired polishing profile is within a preset allowable range.
5. The polishing apparatus according to claim 1 , wherein
when an actual polished profile is measured in a predetermined interval and corrected pressure values are calculated based on a difference between the actual polished profile and the estimated polishing profile, said top ring is to press the front surface of a next object against the polishing surface so as to polish the next object under a polishing condition including a polishing pressure value based on the corrected pressure values when a difference between the actual polished profile and the desired polishing profile is within a preset allowable range.
6. The polishing apparatus according to claim 1 , wherein
said polishing apparatus is constructed and arranged to have polishing of the object stopped or a warning issued when the recommended polishing pressure value falls outside a predetermined allowable range.
7. The polishing apparatus according to claim 1 , further comprising:
a computer for controlling said top ring, said computer including a storage medium reader for reading a program or data from a computer readable storage medium into said computer.
8. A program recorded on a computer readable storage medium, said program for causing a computer to control an apparatus, including a top ring having pressing portions for holding an object to be polished and pressing the object against a polishing surface, to perform operations of:
(a) setting a desired polishing profile;
(b) independently setting a pressure value for each of at least two of the pressing portions, which pressure value corresponds to a pressure that a respective one of each of the at least two pressing portions is to apply on a back surface of the object;
(c) determining an estimated polishing profile of the object based on the pressure values set in (b);
(d) calculating a difference between the desired polishing profile and the estimated polishing profile;
(e) repeating (b)–(d) until the difference between the desired polishing profile and the estimated polishing profile becomes within a predetermined range;
(f) determining a recommended polishing pressure value such that the difference between the desired polishing profile and the estimated polishing profile becomes within the predetermined range, which recommended polishing pressure value corresponds to a pressure that is to be applied by the top ring to the back surface of the object; and
(g) polishing the object by causing the top ring to press a front surface of the object against the polishing surface under a polishing condition including the recommended polishing pressure value.
9. The program according to claim 8 , wherein
the program is also for causing the computer to control the apparatus to perform an operation of stopping polishing of the object or issuing a warning when the recommended polishing pressure falls outside a predetermined allowable range.
10. A computer useable medium having means for storing the program according to claim 8 .
11. A program recorded on a computer readable storage medium, said program for causing a computer to control an apparatus, including a top ring having pressing portions for holding an object to be polished and pressing the object against a polishing surface, to perform operations of:
(a) independently setting a pressure value for each of at least two of the pressing portions, which pressure value corresponds to a pressure that a respective one of each of the at least two pressing portions is to apply on a back surface of the object;
(b) determining an estimated polishing profile of the object based on the pressure values set in (a);
(c) measuring an actual polished profile after the object is polished;
(d) calculating corrected pressure values based on a difference between the actual polished profile and the estimated polishing profile; and
(e) using the corrected pressure values for a next object to be polished.
12. The program according to claim 11 , wherein
the program is for causing the computer to control the apparatus to use the corrected pressure values for a next object to be polished when a difference between the actual polished profile and the desired polishing profile is within a preset allowable range.
13. The program according to claim 11 , wherein
the program is also for causing the computer to control the apparatus to perform an operation of stopping polishing of the object or issuing a warning when the recommended polishing pressure falls outside a predetermined allowable range.
14. A computer useable medium having means for storing the program according to claim 11 .
15. A program recorded on a computer readable storage medium, said program for causing a computer to control an apparatus, including a top ring having pressing portions for holding an object to be polished and pressing the object against a polishing surface, to perform operations of:
(a) independently setting a pressure value for each of at least two of the pressing portions, which pressure value corresponds to a pressure that a respective one of each of the at least two pressing portions is to apply on a back surface of the object;
(b) determining an estimated polishing profile of the object based on the pressure values set in (a);
(c) measuring an actual polished profile in a predetermined interval;
(d) calculating corrected pressure values based on a difference between the actual polished profile and the estimated polishing profile; and
(e) using the corrected pressure values for a next object to be polished.
16. The program according to claim 15 , wherein
the program is for causing the computer to control the apparatus to use the corrected pressure values for a next object to be polished when a difference between the actual polished profile and the desired polishing profile is within a preset allowable range.
17. The program according to claim 15 , wherein
the program is also for causing the computer to control the apparatus to perform an operation of stopping polishing of the object or issuing a warning when the recommended polishing pressure falls outside a predetermined allowable range.
18. A computer useable medium having means for storing the program according to claim 15 .
19. A method for estimating a polishing profile or a polishing amount when polishing an object by using a top ring to press a front surface of the object against a polishing surface, with the top ring having at least two pressing portions each capable of independently applying a desired pressure on a back surface of the object, said method comprising:
setting back surface pressure distributions of the object;
calculating front surface pressure distributions of the object corresponding to said back surface pressure distributions;
storing said back surface pressure distributions and said front surface pressure distributions in a memory medium so as to provide stored back surface pressure distributions and stored front surface pressure distributions;
setting a desired back surface pressure distribution of the object;
synthesizing said desired back surface pressure distribution from a combination of said stored back surface pressure distributions;
calculating a desired front pressure distribution corresponding to said desired back surface pressure distribution based on a combination of said stored back surface pressure distributions;
calculating an estimated polishing profile or polishing amount of the object based on said desired front pressure distribution and a predetermined equation which includes a polishing amount value and a pressure value as parameters; and
determining set pressure values that provide a desired polishing profile, by
(a) determining a difference in a polishing amount between a polishing profile of the object during polishing and said estimated polishing profile,
(b) correcting said desired front pressure distribution based on the difference in polishing amount so as to provide a corrected front pressure distribution,
(c) determining an estimated polishing profile as obtained by said corrected desired front pressure distribution, and
(d) repeating (a)–(c) until a difference between a polishing profile of the object during polishing and said estimated polishing profile determined in (c) becomes within a predetermined range.
20. A method for estimating a polishing profile or a polishing amount when polishing an object by using a top ring to press a front surface of the object against a polishing surface, with the top ring having at least two pressing portions each capable of independently applying a desired pressure on a back surface of the object, said method comprising:
setting back surface pressure distributions of the object;
calculating front surface pressure distributions of the object corresponding to said back surface pressure distributions;
storing said back surface pressure distributions and said front surface pressure distributions in a memory medium so as to provide stored back surface pressure distributions and stored front surface pressure distributions;
setting a desired back surface pressure distribution of the object;
synthesizing said desired back surface pressure distribution from a combination of said stored back surface pressure distributions;
calculating a desired front pressure distribution corresponding to said desired back surface pressure distribution based on a combination of said stored back surface pressure distributions;
calculating an estimated polishing profile or polishing amount of the object based on said desired front pressure distribution and a predetermined equation which includes a polishing amount value and a pressure value as parameters; and
updating said estimated polishing profile based on a measured polishing profile of the object.
21. A method for estimating a polishing profile or a polishing amount when polishing an object by using a top ring to press a front surface of the object against a polishing surface, with the top ring having at least two pressing portions each capable of independently applying a desired pressure on a back surface of the object, said method comprising:
setting back surface pressure distributions of the object;
calculating front surface pressure distributions of the object corresponding to said back surface pressure distributions;
storing said back surface pressure distributions and said front surface pressure distributions in a memory medium so as to provide stored back surface pressure distributions and stored front surface pressure distributions;
setting a desired back surface pressure distribution of the object;
synthesizing said desired back surface pressure distribution from a combination of said stored back surface pressure distributions;
calculating a desired front pressure distribution corresponding to said desired back surface pressure distribution based on a combination of said stored back surface pressure distributions; and
calculating an estimated polishing profile or polishing amount of the object based on said desired front pressure distribution, a predetermined equation which includes a polishing amount value and a pressure value as parameters, and results of measurement of a configuration of a polished object performed by a configuration monitor capable of measuring an edge configuration of the polished object.
22. A method for polishing an object by using a polishing apparatus including a top ring having pressing portions to press a back surface of the object such that a front surface of the object is pressed against a polishing surface, said method comprising:
(a) setting a desired polishing profile;
(b) independently setting a pressure value for each of at least two of the pressing portions, which pressure value corresponds to a pressure that a respective one of each of the at least two pressing portions is to apply on a back surface of the object;
(c) determining an estimated polishing profile of the object based on the pressure values set in (b);
(d) calculating a difference between said desired polishing profile and said estimated polishing profile;
(e) repeating (b)–(d) until the difference between said desired polishing profile and said estimated polishing profile becomes within a predetermined range;
(f) determining a recommended polishing pressure value such that the difference between said desired polishing profile and said estimated polishing profile becomes within the predetermined range, which recommended polishing pressure value corresponds to a pressure that is to be applied by the top ring to the back surface of the object; and
(g) polishing the object by causing the top ring to press a front surface of the object against the polishing surface under a polishing condition including said recommended polishing pressure value.
23. The method according to claim 22 , further comprising:
measuring an actual polished profile after the object is polished;
calculating corrected pressure values based on a difference between said actual polished profile and said estimated polishing profile; and
using said corrected pressure values for a next object to be polished.
24. The method according to claim 23 , wherein
using said corrected pressure values for a next object to be polished comprises using said corrected pressure values when a difference between said actual polished profile and said desired polishing profile is within a preset allowable range.
25. The method according to claim 22 , further comprising:
measuring an actual polished profile of the object in a predetermined interval;
calculating corrected pressure values based on a difference between said actual polished profile and said estimated polishing profile; and
using said corrected pressure values for a next object to be polished.
26. The method according to claim 25 , wherein
using said corrected pressure values for a next object to be polished comprises using said corrected pressure values when a difference between said actual polished profile and said desired polishing profile is within a preset allowable range.
27. The method according to claim 22 , further comprising:
stopping polishing of the object or issuing a warning when said recommended polishing pressure value falls outside a predetermined allowable range.