Coupling mechanism, substrate polishing apparatus, method of determining position of rotational center of coupling mechanism, program of determining position of rotational center of coupling mechanism, method of determining maximum pressing load of rotating body, and program of determining maximum pressing load of rotating body

Patent metadata

Field	Value
Publication number	US-9849557-B2
Application number	US-201615007039-A
Country	US
Kind code	B2
Filing date	Jan 26, 2016
Priority date	Jan 30, 2015
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A coupling mechanism which enables a rotating body to follow an undulation of a polishing surface without generating flutter or vibration of the rotating body, and can finely control a load on the rotating body on a polishing surface in a load range which is smaller than the gravity of rotating body is disclosed. The coupling mechanism includes an upper spherical bearing and a lower spherical bearing disposed between a drive shaft and the rotating body. The upper spherical bearing has a first concave contact surface and a second convex contact surface which are in contact with each other, and the lower spherical bearing has a third concave contact surface and a fourth convex contact surface which are in contact with each other. The first concave contact surface and the second convex contact surface are located above the third concave contact surface and the fourth convex contact surface. The first concave contact surface, the second convex contact surface, the third concave contact surface, the fourth convex contact surface are arranged concentrically.

First claim

What is claimed is:

1. A coupling mechanism for tiltably coupling a rotating body to a drive shaft, comprising:
an upper spherical bearing and a lower spherical bearing disposed between the drive shaft and the rotating body,
wherein the upper spherical bearing includes a first sliding-contact member and a second sliding-contact member which are sandwiched between the drive shaft and the rotating body,
the first sliding-contact member has a first concave contact surface, and the second sliding-contact member has a second convex contact surface which is in contact with the first concave contact surface,
the lower spherical bearing includes a third sliding-contact member attached to the drive shaft, and a fourth sliding-contact member attached to the rotating body,
the third sliding-contact member has a third concave contact surface, and the fourth sliding-contact member has a fourth convex contact surface which is in contact with the third concave contact surface,
the first concave contact surface and the second convex contact surface are located above the third concave contact surface and the fourth convex contact surface, and
the first concave contact surface, the second convex contact surface, the third concave contact surface, and the fourth convex contact surface are arranged concentrically.

2. The coupling mechanism according to claim 1 , wherein each of the first concave contact surface and the second convex contact surface has a shape of a part of an upper half of a spherical surface having a first radius, and
each of the third concave contact surface and the fourth convex contact surface has a shape of a part of an upper half of a spherical surface having a second radius which is smaller than the first radius.

3. The coupling mechanism according to claim 1 , wherein the upper spherical bearing and the lower spherical bearing have a same rotational center, and the rotational center is located below the first concave contact surface, the second convex contact surface, the third concave contact surface, and the fourth convex contact surface.

4. The coupling mechanism according to claim 3 , wherein a distance from a bottom end surface of the rotating body to the rotational center can be changed by selecting radii of curvature of the first concave contact surface, the second convex contact surface, the third concave contact surface, and the fourth convex contact surface.

5. The coupling mechanism according to claim 3 , wherein the rotational center is located on a bottom end surface of the rotating body.

6. The coupling mechanism according to claim 3 , wherein the rotational center coincides with a center of inertia of a displacement portion which can tilt about the rotational center.

7. The coupling mechanism according to claim 3 , wherein the rotational center is located between a bottom end surface of the rotating body and a center of inertia of a displacement portion which can tilt about the rotational center.

8. The coupling mechanism according to claim 3 , wherein the rotational center is located below a bottom end surface of the rotating body.

9. The coupling mechanism according to claim 1 , wherein one of the first sliding-contact member and the second sliding-contact member has a Young's modulus which is equal to or lower than a Young's modulus of the other, or has a damping coefficient which is higher than a damping coefficient of the other.

10. A substrate polishing apparatus comprising:
a polishing table for supporting a polishing pad; and
a polishing head configured to press a substrate against the polishing pad,
wherein the polishing head is coupled to a drive shaft through the coupling mechanism according to claim 1 .

11. A substrate polishing apparatus comprising:
a polishing table for supporting a polishing pad;
a polishing head configured to press a substrate against the polishing pad; and
a dresser which is pressed against the polishing pad,
wherein the dresser is coupled to a drive shaft through the coupling mechanism according to claim 1 .

12. The substrate polishing apparatus according to claim 11 , further comprising:
a pad-height measuring device configured to measure a height of a polishing surface of the polishing pad,
wherein the pad-height measuring device includes:
a pad-height sensor secured to a dresser arm which rotatably supports the drive shaft; and
a sensor target secured to the drive shaft.

13. A method of determining a position of a rotational center of a coupling mechanism which includes an upper spherical bearing and a lower spherical bearing having a same rotational center and tiltably couples a rotating body to a drive shaft, comprising:
specifying an equation of motion for a tilting motion of a displacement portion which can tilt about the rotational center when the rotating body is in sliding contact with a polishing pad supported by a rotating polishing table, while rotating the rotating body;
specifying a stability condition expression for the tilting motion for preventing flutter or vibration of the rotating body, based on the equation of motion for the tilting motion;
calculating a range of a position of the rotational center for preventing the flutter or vibration of the rotating body, based on the stability condition expression for the tilting motion; and
determining the position of the rotational center which falls within the calculated range.

14. The method of determining the position of the rotational center according to claim 13 , wherein said determining comprises, if a center of inertia of the displacement portion falls within the calculated range, determining the position of the rotational center which coincides with the center of inertia.

15. A non-transitory computer-readable storage medium storing a program of determining a position of a rotational center of a coupling mechanism which includes an upper spherical bearing and a lower spherical bearing having a same rotational center and tiltably couples a rotating body to a drive shaft, the program causing a computer to perform operations of:
calculating a range of the position of the rotational center for preventing flutter or vibration of the rotating body, from a stability condition expression for a tilting motion, which is specified based on an equation of motion for the tilting motion of a displacement portion which can tilt about the rotational center when the rotating body is in sliding contact with a polishing pad supported by a rotating polishing table, while rotating the rotating body; and
determining the position of the rotational center which falls within the calculated range.

16. The non-transitory computer-readable storage medium storing the program of determining the position of the rotational center according to claim 15 , wherein causing the computer to perform an operation of said determining comprises causing the computer to perform an operation of, if a center of inertia of the displacement portion falls within the calculated range, determining the position of the rotational center which coincides with the center of inertia.

17. A method of determining a maximum pressing force of a rotating body which is tiltably coupled to a drive shaft through a coupling mechanism which includes an upper spherical bearing and a lower spherical bearing having a same rotational center, comprising:
specifying an equation of motion for a translational motion and an equation of motion for a tilting motion of a displacement portion which can tilt about the rotational center when the rotating body is in sliding contact with a polishing pad supp

Assignees

• Ebara Corp

Inventors

• Shinozaki Hiroyuki

Classifications

• B24B53/12

  Dressing tools; Holders therefor · CPC title

• B24B27/0084 Primary

  the grinding wheel support being angularly adjustable · CPC title

• B24B37/105

  the workpieces or work carriers being actively moved by a drive, e.g. in a combined rotary and translatory movement · CPC title

• B24D7/16

  Bushings; Mountings · CPC title

• B24B53/017

  Devices or means for dressing, cleaning or otherwise conditioning lapping tools · CPC title