Polishing method and apparatus

• US 20040005845A1
• Filed: 04/25/2003
• Published: 01/08/2004
• Est. Priority Date: 04/26/2002
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kitajima, Tomohiko, Yasuhara, Gen
• Granted Patent: US 7,101,252 B2
• Time in Patent Office: Days
• US Class Current: 451/57
• CPC Class Codes: B24B 37/005 Control means for lapping machines or devices
• CPC Class Codes: B24B 37/042 operating processes therefor
• CPC Class Codes: B24B 49/16 taking regard of the load
• CPC Class Codes: H01L 21/31053 involving a dielectric removal step

Abstract

A chemical mechanical polishing method for polishing an oxide film and a protective film formed on a substrate having recesses comprises four steps. The first step planarizes the oxide film using a polishing pad and a polishing agent containing cerium oxide particles by causing relative rotational motion between the substrate and the polishing pad. The second step continues polishing the oxide film to maintain the planarized property of the oxide film. The third step polishes the oxide film until at least a portion of the protective film becomes exposed. The fourth step polishes the oxide film until the oxide film is substantially removed and the protective film is substantially exposed. During the four steps, torque values are measured on the substrate or the polishing pad, and changes in torque with time are calculated. This information is used to determine the status of each of the steps during the polishing run.

Claims

1. A polishing method for chemical mechanical polishing of an oxide film adhered on a protective film formed on a substrate having recesses, the method comprising:

a first step of planarizing the oxide film by bringing the oxide film into contact with a polishing pad, supplying a polishing agent containing cerium oxide particles between the oxide film and the polishing pad, and causing relative rotational motion between the substrate and the polishing pad;

a second step of continuing to polish the oxide film once the oxide film has been planarized, thereby maintaining the planarized property of the oxide film;

a third step of continuing to polish the oxide film until at least a portion of the protective film becomes exposed;

a fourth step of continuing to polish the oxide film until the oxide film is substantially removed and the protective film is substantially exposed;

measuring torque values on the substrate or on the polishing pad either continuously or at intervals during the first through fourth steps; and

calculating changes in torque with time to determine the status of each of the first through fourth steps concurrently with the polishing method.

2. The polishing method of claim 1, wherein the measuring of the torque comprises measuring one or more of a driving current, a driving voltage, and a driving power of a mechanism that rotates the substrate or the polishing pad and calculating the torque.

3. The polishing method of claim 1, wherein one or more transition points between at least two adjacent steps of the first through fourth steps are detected based at least in part on the calculated changes in torque with time.

4. The polishing method of claim 3, wherein a transition point is detected between the first and second steps by determining a time point at which the calculated change in torque with time goes from a positive value to a value of approximately zero.

5. The polishing method of claim 3, wherein a transition point is detected between the second and third steps by determining a time point at which the calculated change in torque with time goes from a value of approximately zero to a negative value.

6. The polishing method of claim 3, wherein a transition point is detected between the third and fourth steps by determining a time point at which the calculated change in torque with time goes from a negative value to a value of approximately zero.

7. The polishing method of claim 1, wherein an anomaly in at least one of the first through fourth steps is detected by comparing the calculated changes in torque with time to a reference pattern that is predetermined based on one or more of the oxide film, the protective film, and the polishing agent.

8. The polishing method of claim 3, wherein an anomaly is detected in at least one of the first through fourth steps when no transition point is detected between at least two adjacent steps of the first through fourth steps.

9. The polishing method of claim 7, wherein an anomaly in at least one of the first through fourth steps is detected when at least one of the calculated changes in torque with time deviates from its corresponding value in the reference pattern by an amount that exceeds a predetermined allowable value.

10. The polishing method of claim 7, wherein an anomaly in at least one of the first through fourth steps is detected when the actual time required for one of the steps deviates from the time required for the corresponding step in the reference pattern by an amount that exceeds a predetermined allowable value.

11. The polishing method of claim 7, wherein an anomaly in at least one of the first and second steps is detected when the calculated changes in torque with time provide no indication of the presence of the second step.

12. The polishing method of claim 3, wherein each of the first through third steps can use different polishing agents, and wherein the composition of the polishing agent used for each step is based at least in part on properties associated with the oxide film or on the detected transition points.

13. The polishing method of claim 12, wherein the polishing agent used in the first step comprises a self-stopping type of polishing agent.

14. The polishing method of claim 13, wherein the polishing agent used in the second step comprises either a self-stopping type of polishing agent with water added or a highly selective type of polishing agent.

15. The polishing method of claims 13 or 14, wherein the polishing agent used in the third step comprises either a self-stopping type of polishing agent with water added or a highly selective type of polishing agent.

16. The polishing method of claim 3, wherein the type of polishing pad used for each of the first through third steps is chosen based at least in part on properties associated with the oxide film or on the detected transition points.

17. The polishing method of claim 16, wherein the polishing pads used for the first and second steps have a hardness level that is greater than that of the polishing pad used for the third step.

18. The polishing method of claim 3, wherein a different pressure can be applied between the polishing pad and the substrate during each of the first through third steps, each applied pressure being chosen based at least in part on properties associated with the oxide film during each step and on the detected transition points.

19. The polishing method of claim 18, wherein the applied pressure between the polishing pad and the substrate during the first and second steps is greater than the applied pressure during the third step.

20. A polishing device for chemically mechanically polishing an oxide film adhered on a protective film formed on a substrate having recesses, comprising:

a substrate holding section for holding the substrate;

a polishing section having a polishing pad disposed opposite the substrate holding section;

a driving mechanism for rotating the one or both of the substrate holding section and the polishing pad;

a polishing agent supplier for supplying polishing agent between the substrate and the polishing pad;

a water supplier for supplying water between the substrate and the polishing pad;

a torque measuring device for measuring torque values on the driving mechanism either continuously or at intervals; and

a process monitoring device for monitoring the real-time status of a polishing run by calculating changes in torque with time using the measured torque values.

21. The polishing device of claim 20, wherein the polishing run comprises:

a first step of planarizing the oxide film by bringing the oxide film into contact with a polishing pad, supplying a polishing agent containing cerium oxide particles between the oxide film and the polishing pad, and causing relative rotational motion between the substrate and the polishing pad;

a second step of continuing to polish the oxide film once the oxide film has been planarized, thereby maintaining the planarized property of the oxide film;

a third step of continuing to polish the oxide film until at least a portion of the protective film becomes exposed; and

a fourth step of continuing to polish the oxide film until the oxide film is substantially removed and the protective film is substantially exposed.

22. The polishing device of claim 21, wherein monitoring the real-time status of a polishing run comprises detecting transition points between adjacent steps of the first through fourth steps and detecting anomalies in at least one of the first through fourth steps.

23. The polishing device of claim 20, wherein the torque measuring device measures torque values based at least in part on one or more of the driving current, driving voltage, and driving power applied to the driving mechanism.

24. The polishing device of claim 22, wherein the process monitoring device stops the driving mechanism when an anomaly is detected in any of the first through fourth steps.

25. The polishing device of claim 22, wherein the process monitoring device controls one or both of the polishing agent supplier and the water supplier so that each of the first through fourth steps can use different polishing agents or water, and the composition of the polishing agent used for any particular step is based at least in part on properties associated with the oxide film or on the detected transition points.

26. The polishing device of claim 22 including a plurality of polishing pads having different hardness values, wherein the process monitoring device controls one or both of the substrate holding section and the polishing section so that polishing pads are chosen for use in each of the first through third steps based at least in part on properties associated with the oxide film or on the detected transition points.

27. The polishing device of claim 22, wherein the process monitoring device controls one or both of the substrate holding section and the polishing section so that a different pressure can be applied between the polishing pad and the substrate for each of the first through third steps, each applied pressure being chosen based at least in part on properties associated with the oxide film during each step and on the detected transition points.