Apparatus for aligning a surface of an active retainer ring with a wafer surface for chemical mechanical polishing

• US 6,709,322 B2
• Filed: 03/29/2001
• Issued: 03/23/2004
• Est. Priority Date: 03/29/2001
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Lam Research Corporation
• Inventors: Williams, Damon Vincent, Saldana, Miguel Angel
• Primary Examiner(s): Wilson, Lee D.
• Application Number:
  US09/823,169
• Publication Number:
  US 20020151254A1
• Time in Patent Office: 1,090 Days
• Field of Search: 451/5, 451/6, 451/11, 451/26, 451/36, 451/41, 451/57, 451/285, 451/286, 451/287, 451/288, 451/289, 451/397
• US Class Current: 451/397
• CPC Class Codes: B24B 37/16 characterised by the shape of the lapping plate surface, e.g. grooved
• CPC Class Codes: B24B 37/32 Retaining rings

Abstract

A CMP system and methods reduce a cause of differences between an edge profile of a chemical mechanical polished edge of a wafer and a center profile of a chemical mechanical polished central portion of the wafer within the edge. The wafer is mounted on a carrier surface of a wafer carrier so that a wafer axis of rotation is gimballed for universal movement relative to a spindle axis of rotation of a wafer spindle. A retainer ring limits wafer movement on the carrier surface perpendicular to the wafer axis. The retainer ring is mounted on and movable relative to the wafer carrier. A linear bearing is configured with a housing and a shaft so that a direction of permitted movement between the wafer carrier and the retainer ring is only movement parallel to the wafer axis, so that a wafer plane and a retainer ing may be co-planar.

Claims

1. Apparatus for controlling a positional relationship in a chemical mechanical polishing system, the apparatus comprising:

a wafer carrier plate having a carrier plate surface configured to mount a wafer for contact with a chemical mechanical polishing surface;

a retainer ring assembly mounted on and for movement relative to the wafer carrier plate to retain the wafer in a desired position on the carrier surface, the retainer ring assembly having a ring surface configured to contact the polishing surface; and

a bearing assembly mounted between the wafer carrier plate and the retainer ring assembly to limit the movement of the retainer ring assembly relative to the carrier plate so that the ring surface is positioned parallel to the carrier plate surface.

2. Apparatus as recited in claim 1, wherein:

the bearing assembly is configured with a bearing housing mounted on one of the wafer carrier plate and the retainer ring, and a bearing shaft is mounted on the other of the wafer carrier plate and the retainer ring assembly, the bearing shaft being received in the bearing housing.

3. Apparatus as recited in claim 1, further comprising:

a drive mounted between the wafer carrier plate and the retainer ring assembly to control a reveal position of the ring surface relative the carrier plate surface.

4. Apparatus as recited in claim 3, wherein:

the bearing assembly is effective during the control of the reveal position of the ring surface relative the carrier plate surface to maintain the ring surface parallel to the carrier plate surface.

5. Apparatus as recited in claim 1, further comprising:

a spindle configured to mount the wafer carrier plate for rotation, the spindle having a base closely adjacent to the wafer carrier plate, the base being configured to receive a first gimbal member;

a second gimbal member configured to cooperate with the first gimbal member and secured to the wafer carrier plate to allow the wafer carrier plate to be positioned in any position in a range of polishing positions in which the carrier plate surface is parallel to the polishing surface; and

wherein with the carrier plate surface parallel to the polishing surface the bearing assembly is effective to limit the movement of the retainer ring assembly relative to the carrier plate so that the ring surface is positioned co-planar with the polishing surface.

6. Apparatus for controlling positional relationships with respect to a chemical mechanical polishing surface, the apparatus comprising:

a spindle;

a wafer carrier having a wafer carrier surface;

a gimbal assembly having a first gimbal member mounted on the spindle and a second gimbal member mounted on the carrier, the second gimbal member mating with the first gimbal member to permit gimballing motion of the carrier relative to the spindle into a polishing position in which the wafer carrier surface is parallel to the polishing surface;

a retainer ring assembly mounted on and for movement relative to the wafer carrier, the retainer ring assembly having a ring surface configured to contact the polishing surface; and

a bearing assembly mounted between the wafer carrier and the retainer ring assembly, the bearing assembly being configured to limit the movement of the retainer ring assembly relative to the carrier so that the ring surface is positioned parallel to the carrier surface.

7. Apparatus as recited in claim 6, further comprising:

a drive positioned between the wafer carrier and the retainer ring assembly to move the ring surface relative the carrier surface.

8. Apparatus as recited in claim 6, wherein the spindle is configured to provide a rotational force and the gimbal assembly is configured with at least one connector for transferring the rotational force to the carrier.

9. Apparatus as recited in claim 6, wherein:

the bearing assembly is configured with a linear bearing housing on one of the wafer carrier and the retainer ring assembly and with a linear bearing shaft on the other of the wafer carrier and the retainer ring assembly.

10. Apparatus as recited in claim 6, further comprising:

a sensor mounted on the spindle and having a force input connected to the first gimbal member to receive a polishing force.

11. Apparatus as recited in claim 10, wherein:

the spindle is configured with a cavity to receive and position the sensor closely adjacent to the wafer carrier; and

the wafer carrier is configured with a recess to receive the first and second gimbal members and enable the force input of the sensor to be closely adjacent to the wafer carrier surface.

12. Apparatus for controlling positional relationships in a chemical mechanical polishing system, the apparatus comprising:

a spindle configured to provide a rotational force, the spindle having a first gimbal member;

a gimbal assembly having a second gimbal member configured to cooperate with the first gimbal member to permit gimballing motion in which the second member moves universally relative to the spindle, the gimbal assembly having a drive connector for transferring the rotational force;

a wafer carrier mounted on the second gimbal member and provided with a wafer carrier surface, the gimbal members allowing the gimballing motion of the wafer carrier into a polishing position in which the wafer carrier surface is parallel to the polishing surface, the wafer carrier having a drive socket configured to receive the drive connector and allow the gimballing motion while transferring the rotational force to the carrier;

a retainer ring assembly mounted on and for movement relative to the wafer carrier into a reveal position to provide a reveal for retaining the wafer on the wafer carrier surface, the retainer ring assembly having a ring surface configured to contact the polishing surface; and

a linear bearing assembly mounted separately from the spindle and between the wafer carrier and the retainer ring assembly to permit only limited movement of the retainer ring assembly relative to the carrier, the limited movement being with the ring surface oriented parallel to the carrier surface during the gimballing motion.

13. Apparatus as recited in claim 12, further comprising:

a drive positioned between the wafer carrier and the retainer ring assembly to move the ring surface relative to the wafer carrier surface and permit the selection of a value of the reveal.

14. Apparatus for controlling structural movement of a semiconductor wafer carrier in chemical mechanical polishing, the apparatus comprising:

a carrier plate having a wafer mount surface centered relative to a carrier axis of rotation of the carrier plate;

a retainer ring surrounding the wafer mount surface;

a connector arrangement configured to mount the retainer ring on and for movement relative to the carrier plate in a plurality of directions including a first direction parallel to the carrier axis and other directions not parallel to the carrier axis; and

a linear bearing arrangement having at least one first unit secured to the carrier plate and at least one second unit secured to the retainer ring, the at least one second unit being movable relative to the at least one first unit, the at least one first unit and the at least one second unit being configured to resist all of the movement of the retainer ring relative to the carrier plate in the plurality of directions except movement in the first direction parallel to the carrier axis.

15. Apparatus according to claim 14, wherein:

the wafer mount surface is configured to be coaxial with the carrier axis and centrally located adjacent to the axis; and

the linear bearing arrangement includes an array of linear bearings positioned along an arcuate path around the central wafer mount surface, each of the linear bearings has one of the at least one first units secured to the carrier plate radially outwardly of the wafer mount surface, each of the linear bearings has one of the at least one second units secured to the retainer ring radially outwardly of the wafer mount surface.

16. Apparatus according to claim 14, further comprising:

a coupler having a drive axis of rotation and configured to rotate the carrier plate, the coupler having a first gimbal surface configured to cooperate with a second gimbal surface;

wherein the carrier plate is provided with the second gimbal surface cooperating with the first gimbal surface to permit the carrier plate and the retainer ring on the carrier plate to move relative to the coupler so that the carrier axis may tilt with respect to the drive axis; and

wherein during the movement of the carrier plate relative to the coupler the linear bearing arrangement permits movement of the retainer ring relative to the carrier plate only in the first direction parallel to the carrier axis.

17. Apparatus according to claim 16, wherein separate polishing forces are applied to the retainer ring and to the carrier plate and each of the separate polishing forces has a parallel component parallel to the carrier axis and a component other than parallel to the carrier axis, the apparatus further comprising:

a sensor mounted on the coupler and having a force input, the sensor being configured so that the force input may be contacted by the first gimbal surface; and

wherein the configuration of the connector for mounting the retainer ring on and for movement relative to the carrier plate, and the linear bearing arrangement permitting movement of the retainer ring relative to the carrier plate only in the first direction parallel to the carrier axis, enable only the parallel component of the separate polishing force applied to the retainer ring to be applied to the carrier plate for sensing by the sensor.