Control of chemical mechanical polishing pad conditioner directional velocity to improve pad life

• US 6,910,947 B2
• Filed: 11/30/2001
• Issued: 06/28/2005
• Est. Priority Date: 06/19/2001
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Paik, Young Joseph
• Primary Examiner(s): Rose, Robert A.
• Application Number:
  US09/998,372
• Publication Number:
  US 20020197934A1
• Time in Patent Office: 1,306 Days
• Field of Search: 451/21, 451/5, 451/8, 451/41, 451/288, 451/287, 451/56
• US Class Current: 451/21
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 37/042 operating processes therefor
• CPC Class Codes: B24B 49/03 according to the final size of the previously ground workpiece
• CPC Class Codes: B24B 49/18 taking regard of the presence of dressing tools
• CPC Class Codes: B24B 53/017 Devices or means for dressing, cleaning or otherwise conditioning lapping tools
• CPC Class Codes: G05B 19/00 Programme-control systems
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 2219/32053 Adjust work parameter as function of other cell
• CPC Class Codes: G05B 2219/32065 Synchronise set points of processes
• CPC Class Codes: G05B 2219/45031 Manufacturing semiconductor wafers
• CPC Class Codes: H01L 21/31053 involving a dielectric removal step
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/67276 Production flow monitoring, e.g. for increasing throughput program-control systems per se G05B19/00, e.g. total factory control G05B19/418
• CPC Class Codes: H01L 22/20 Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
• CPC Class Codes: Y02P 80/40 Minimising material used in manufacturing processes
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A method, apparatus and medium of conditioning a planarizing surface includes installing a wafer to be polished in a chemical mechanical polishing (CMP) apparatus having a polishing pad and a conditioning disk, polishing the wafer under a first set of pad conditioning parameters selected to maintain wafer material removal rates with preselected minimum and maximum removal rates, determining a wafer material removal rate occurring during the polishing step, calculating updated pad conditioning parameters to maintain wafer material removal rates within the maximum and minimum removal rates, and conditioning the polishing pad using the updated pad conditioning parameters, wherein the updated pad conditioning parameters are calculated by a pad wear and conditioning model that predicts the wafer material removal rate of the polishing pad based upon the rotational speed and direction of the conditioning disk.

Claims

1. A method of conditioning a planarizing surface in a chemical mechanical polishing (CMP) apparatus having a polishing pad against which a wafer is positioned for removal of material therefrom and a conditioning disk is positioned for conditioning of the polishing pad, comprising the steps of:

a) providing a pad wear and conditioning model that defines wafer material removal rate as a function of at least one pad conditioning parameter selected from the group including rotation speed and rotation direction of a conditioning disk;

b) polishing a wafer in a CMP apparatus under a first set of pad conditioning parameters selected to maintain wafer material removal rates within preselected minimum and maximum removal rates;

c) determining a wafer material removal rate occurring during said polishing step; and

d) calculating updated pad conditioning parameters based upon said determined wafer material removal rate of said step (c) and the pad wear and conditioning model of said step (a).

2. The method of claim 1, wherein step (d) includes calculating updated pad conditioning parameters to maintain wafer material removal rate within the maximum and minimum removal rates.

3. The method of claim 1, wherein the first set of pad conditioning parameters are determined empirically.

4. The method of claim 1, wherein the first set of pad conditioning parameters are determined using historical data.

5. The method of claim 1, wherein the first set of pad conditioning parameters are determined using the results of the design of experiment (DOE).

6. The method of claim 1, wherein the pad conditioning parameter of the pad wear and pad recovery model further comprises a conditioning parameter selected from the group consisting of frequency of conditioning, duration of conditioning, and translational speed of conditioning disk during conditioning.

7. The method of claim 1, wherein the updated pad conditioning parameters are calculated by determining the difference between an output of the pad wear and conditioning model and said determined wafer material removal rate of step (c).

8. The method of claim 7, wherein said difference is adjusted using an estimate gain prior to calculating updated conditioning parameters.

9. The method of claim 8, wherein the gain is selected to represent variability or reliability in the measured parameter.

10. The method of claim 1, wherein the updated pad conditioning parameters are updated according to the equation k=(k₁)+g*(k−

(k₁)), where k is a measured wafer material removal rate, k₁ is a calculated wafer material removal rate, g is the estimate gain, and (k−

(k₁)) is the prediction error.

11. The method of claim 1, wherein the steps (b) through (d) are repeated.

12. The method of claim 1, wherein the step of calculating updated pad conditioning parameters in step (d) comprises executing a recursive optimization process.

13. The method of claim 1, wherein the maximum value for wafer material removal rate is the saturation point of the wafer material removal rate vs. conditioning down force curve.

14. The method of claim 1, wherein the maximum value for wafer material removal rate is the initial rate.

15. The method of claim 1, wherein the minimum value for wafer material removal rate is defined by the maximum acceptable wafer polishing time.

16. The method of claim 1, wherein the wafer material removal rate is defined by the equation ${{{R_{}^{}}_{}^{}}_{}^{}}_{}^{}$

 

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where ω

_disk is the angular velocity of the conditioning disk during conditioning of the polishing pad, t is the time of conditioning, f is the frequency of condition, direction is the spinning direction of the conditioning disk, and T₂ is the sweeping speed of the conditioning disk during conditioning.

30. The method of claim 1, wherein the polishing pads is conditioned during polishing of a wafer.

31. The method of claim 1, wherein the polishing pad is conditioned between between wafer polishing.

32. The method of claim 1, further comprising conditioning the polishing pad using the updated conditioning parameters.

17. A method of developing a pad wear and pad conditioning model for optimization of the pad conditioning for polishing pads used to remove material from a wafer, comprising the steps of:

a) determining the relationship between at least one pad conditioning parameter and wafer material removal rate; and

b) determining maximum and minimum values for each of the at least one pad conditioning parameters and the wafer material removal rate; and

c) recording the relationships and minimum and maximum values of the at least one pad conditioning parameter and the wafer removal rate.

18. The method of claim 17, wherein the at least one pad conditioning parameter comprises a plurality of parameters and the wafer removal rate is defined as a weighted function of the plurality of pad conditioning parameters.

19. The method of claim 17, wherein the at least one pad conditioning parameter comprises conditioning disk rotational speed.

20. The method of claim 19, wherein the at least one pad conditioning parameter further comprises conditioning disk rotational direction.

21. The method of claim 17, where the at least one pad conditioning parameter comprises one or more parameters selected from the group consisting of conditioning disk down force, conditioning disk rotational rate and direction, frequency and duration of conditioning and conditioning disk translational speed.

22. The method of claim 17, wherein the relationship between the at least one conditioning parameter and wafer removal rate is determined by incrementally varying the conditioning parameter and measuring the resultant wafer removal rate.

23. The method of claim 17, wherein the maximum value for the conditioning parameter is the value above which no incremental increase of the wafer removal rate is observed.

24. The method of claim 17, wherein the minimum value for the conditioning parameter is the value that provides the minimum wafer removal rate.

25. The method of claim 17, further comprising:

polishing a wafer in a chemical mechanical polishing (CMP) apparatus under a first set of pad conditioning parameters selected to maintain wafer material removal rates within preselected minimum and maximum removal rates including conditioning disk rotational speed and direction;

determining a wafer material removal rate occurring during said polishing step; and

calculating updated pad conditioning parameters based upon said determined wafer material removal rate and the pad wear and conditioning model to maintain wafer material removal rates within the maximum and minimum removal rates.

26. The method of claim 25, wherein the updated pad conditioning parameters are calculated by determining the difference between an output of the pad wear and conditioning model and said determined wafer material removal.

27. The method of claim 25, wherein the updated pad conditioning parameters are updated according to the equation k=(k₁)+g*(k−

(k₁)), where k is a measured wafer material removal rate, k₁ is a calculated wafer material removal rate, g is the estimate gain, and (k−

(k₁)) is the prediction error.

28. A method of conditioning a planarizing surface in a chemical mechanical polishing (CMP) apparatus having a polishing pad against which a wafer is positioned for removal of material therefrom and a conditioning disk is positioned for conditioning of the polishing pad, comprising the steps of:

(a) developing a pad wear and pad conditioning model that defines wafer material removal rate as a function of pad conditioning parameters by;

(i) determining the relationship between at least one pad conditioning parameter and wafer material removal rate; and

(ii) determining maximum and minimum values for each of the at least one pad conditioning parameters and the wafer material removal rate; and

(iii) recording the relationships and minimum and maximum values of the at least one pad conditioning parameter and the wafer removal rate;

(b) polishing a wafer in the CMP apparatus under a first set of pad conditioning parameters including conditioning disk rotational speed and direction, selected to maintain wafer material removal rates within preselected minimum and maximum removal rates;

(c) determining a wafer material removal rate occurring during said polishing step; and

(d) calculating updated pad conditioning parameters based upon said determined wafer material removal rate of said step (b) and the pad wear and conditioning model to maintain wafer material removal rates within the maximum and minimum removal rates.

29. A method of conditioning a planarizing surface in a chemical mechanical polishing (CMP) apparatus having a polishing pad against which a wafer is positioned for removal of material therefrom and a conditioning disk is positioned for conditioning of the polishing pad, comprising the steps of:

a) providing a pad wear and conditioning model that defines wafer material removal rate as a function of at least one pad conditioning parameter and that identifies a maximum and minimum value for each of the at least one pad conditioning parameter and the wafer removal rate;

b) polishing a wafer in the CMP apparatus under a first set of pad conditioning parameters selected to maintain wafer material removal rates within preselected minimum and maximum removal rates;

c) determining a wafer material removal rate occurring during said polishing step;

d) calculating updated pad conditioning parameters based upon said determined wafer material removal rate of said step (c) and the pad wear and conditioning model of said step (a) and

e) conditioning the polishing pad using the updated conditioning parameters.