JP2003311607A - Vibration damping in carrier head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce transmission of vibration from a backing assembly to a housing. <P>SOLUTION: A carrier head has the backing assembly with a substrate support surface, the housing connectable to a drive shaft to rotate with the drive shaft around a rotation axis, and a damping material in a load path between the backing assembly and the housing. The damping material reduces transmission of vibrations from the backing assembly to the housing. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

[Cross Reference of Related Applications]
U.S. Patent Application No. 0, filed October 10, 1
It is a continuation-in-part application of the 9 / 975,196 specification, and claims its priority.

[0002]

BACKGROUND The present invention relates generally to chemical mechanical polishing systems and processes.

Integrated circuits are typically formed by the sequential deposition of conductive, semiconductive, and insulating layers on a substrate (particularly a silicon wafer). When a series of layers are deposited and etched sequentially, the outer or top layer of the substrate becomes increasingly textured. This non-planarized surface presents a problem at the photolithographic step of the integrated circuit fabrication process. In particular, if the maximum height difference between the peaks and valleys of the textured surface exceeds the depth of focus of the device, the photolithographic device will not be able to focus the optical image on the photoresist layer. right. Therefore, it is necessary to regularly flatten the substrate surface.

Chemical mechanical polishing (CMP) is one accepted method of planarization. Chemical mechanical polishing generally requires mechanically polishing a substrate with a slurry containing a chemically reactive chemical. During a typical polishing operation, the substrate is held against the rotary polishing pad by the carrier head. The carrier head also
The substrate will rotate and move with respect to the polishing pad. As a result of the movement between the carrier head and the polishing pad,
An abrasive embedded in the polishing pad or included in the polishing slurry planarizes the non-planar substrate surface by polishing the surface.

The polishing process produces vibrations which reduce the quality of the planarization and will damage the polishing equipment. In addition, vibration can create annoying noise.

[0006]

SUMMARY In one aspect, the present invention is directed to a carrier head for placing a substrate on a polishing surface. The carrier head includes a backing assembly having a substrate support surface, a housing connectable to the drive shaft that rotates with the drive shaft about an axis of rotation, and a load path between the backing assembly and the housing. And a buffer material. The cushioning material reduces the transmission of vibrations from the backing assembly to the housing.

Embodiments of the invention may include one or more features. The carrier head includes a gimbal mechanism between the backing assembly and the housing to allow the backing assembly to gimbal with respect to the housing. The backing assembly will include a rigid base, a flexible membrane secured to the rigid base to define a pressurizable chamber, and a compressible film on the bottom surface of the base. The housing will provide the bushing. The gimbal mechanism would include a gimbal rod extending into the bushing to prevent the gimbal rod from moving laterally, while the bushing would allow the gimbal rod to move vertically.

The gimbal mechanism includes a top that connects to the housing and a bottom that connects to the backing assembly, and the cushioning material will separate the top from the bottom. The cushioning material will be attached to at least one of the top and bottom using a pressure sensitive adhesive. The cushioning material will form a generally annular body. The gimbal mechanism includes a substantially flat flex ring that bends in a direction perpendicular to the plane of the flex ring to gimbal the backing assembly to the housing and the cushioning material attached to the flex ring.

The cushioning material will be located in the load path between the gimbal mechanism and the backing assembly. The gimbal mechanism includes a substantially flat flexible ring that bends perpendicular to the plane of the flexible ring, gimbals the backing assembly to the housing, and the cushioning material contacts the flexible ring. The flexible ring may include a plurality of protrusions or flanges that extend into the cushioning material.

The cushioning material will be viscoelastic. When deformed, the cushioning material will not rebound to its original shape. For example, the cushioning material will rebound less than 6 percent of the deformation.

In another aspect, the present invention is directed to a chemical mechanical polishing apparatus including a carrier head.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description, drawings, and claims.

Like reference symbols in the various drawings indicate like elements.

Referring to FIG. 1, a chemical mechanical polishing (CMP) apparatus includes a carrier head 100 for holding a substrate during polishing. A description of a suitable CMP apparatus may be found in US Pat. No. 5,738,574. Its contents are incorporated herein in its entirety.

The carrier head 100 during polishing.
Is the substrate 1 against the polishing pad with a predetermined loading force.
Press 0. At the same time, the motor rotates the carrier head to rotate the substrate. Further, the slider laterally traverses the surface of the polishing pad to the substrate and carrier head 100.
Can be vibrated.

The carrier head 100 includes a vibration damping material to significantly reduce the transfer of vibrational energy to and from adjacent portions to reduce or prevent vibration during polishing. Overall, the cushioning material has significantly better vibration damping properties than both adjacent parts of the sander, which is typically made of a hard material (eg metal). The buffer material is
A viscoelastic material with or without memory, which provides good vibration damping properties, which is a commercially available insulating buffer material, 7911 Zion'sville Road, Indianapolis, IN 46268 E-A-R Special. It is produced by C-1002 which is a composite material.

As shown in FIG. 1, a carrier head 100.
Is a housing 102, a base 104, a gimbal mechanism 1
06, including retaining ring 110 and substrate backing assembly 112 (which may also be considered to include base 104). The housing 102 is substantially cylindrical and can be connected to the drive shaft 74 using a set of bolts (not shown). The drive shaft rotates the housing about axis 107. A passage 126 extends through the housing 102 for pneumatic control of the carrier head, as described below. The housing 102 has a cylindrical bushing 122 that fits into a vertical bore 124 that extends vertically through the housing.

The gimbal mechanism 106 includes the gimbal rod 1
Includes 50 and flex ring 152. Gimbal rod 15
0 fits the bushing 122 so that the rod 150 is free to move vertically within the bore while the bushing 122 prevents lateral movement of the gimbal rod 150. A flexible ring 152 is attached to the flange 220 at the lower end of the gimbal rod 150 by a cushioning material 230.
And is adapted to prevent or reduce the transmission of vibrational energy from the flexure ring 152 to the housing 102 through the gimbal ring 220. The cushioning material 230 is 0.06 inches thick. A pressure sensitive adhesive (not shown) bonds the cushioning material 230 to both the housing 102 and the flex ring 152.

The flexible ring 152 (which is a generally flat annular ring) comprises a generally ring-shaped base 10.
It is attached to 4. The flex ring 152 bends in a direction perpendicular to the plane of the flex ring 152, thereby gimbaling the base 104 in association with the gimbal rod 150 and the housing 102. Gimbal rod 1
By allowing 50 to move vertically within bore 122, the gimbal mechanism also prevents any lateral movement of the base while allowing base 104 to move up and down. The cushioning material 230 allows the gimbal mechanism 106 from the base 104 to the housing 102.
Reduce or prevent the transmission of vibrational energy through.

The outer clamp ring 164 is the base 1
The outer edge of the rolling diaphragm 160 is fixed to 04, while the inner clamp ring 162 fixes the inner edge of the rolling diaphragm 160 to the housing. Accordingly, the rolling diaphragm 160 includes the loading chamber 108 formed by the housing 102, the gimbal rod 106, the gimbal ring 220, the cushioning material 230, the flexible ring 152 and the base 104.
Are sealed in the chamber 108 leaving an opening 126.
Apertures 126 are connected to pumps (not shown), which raise and lower the base by moving fluids (eg, air) into and out of chamber 108, respectively. By controlling the pressure of the fluid injected into the loading chamber 108, the pump can push the base down toward the polishing surface with the desired loading force.

The retaining ring 110 has a base 10
4 is a generally annular ring fixed to 4. During polishing,
Fluid is injected into the loading chamber 108, which creates a pressure within the chamber 108. The generated pressure exerts a downward force on the base 104, which in turn exerts a downward force on the retaining ring 110. The downward force pushes the retaining ring 110 against the polishing pad 32.

The substrate backing assembly 112 includes a flexible diaphragm 116, which is fixed between the retaining ring 110 and the base 104. The inner edge of the flexure diaphragm 116 is secured between the annular lower clamp 172 and the annular upper clamp 174 of the support structure 114. The support plate 170 of the support structure 114 is attached to the lower clamp 172. The flexible diaphragm allows vertical movement of the support plate 170 with respect to the base 104. The support plate 170 is a generally disc-shaped rigid member having a plurality of apertures 176 therethrough (only one is numbered in FIG. 2). The support plate 170 has a lip 178 protruding downward at its outer edge.

A flexible membrane 118 extends around the lip 178 of the support plate 170 and is secured between the support plate 170 and the lower clamp 172 to form a generally disc-shaped lower surface 120. Flexible membranes are formed from flexible and elastic materials such as chloroprene or ethylene propylene rubber. Alternatively, the flexible diaphragm and flexible membrane may be combined in a single piece membrane. The flexible membrane 118, the support structure 114, the flexure diaphragm 116, the sealed volume between the base 104 and the flexure ring 152 define a chamber 190, with only an opening 250 continuing through the gimbal rod 150. A pump (not shown) is connected to the opening 250 so as to control the pressure in the chamber 190 by injecting fluid into the chamber through the opening 250, thereby causing downward pressure on the membrane lower surface 120 to the substrate 10. To control.

Referring to FIGS. 2A and 2B, in another embodiment, a gimbal rod 150 'and a flexure ring 152'.
Is formed as a single part. Further, this embodiment does not include support structure 114 or flexure 116. Rather, the flexible membrane is directly connected to the base 104.

In this embodiment, a cushioning material 230 'is placed between the flex ring 152 and the base 104'.
In particular, flexible ring 152 'includes a plurality of humped projections 240 that extend radially outward into slots 242 in base 104'. The slot 242 is filled with a viscoelastic cushioning material 230 ', the top of the slot being the base l.
It is closed with an annular ring 244 which is fixed to the rest of 04 '. For example, the cushioning material can include a bottom layer between the protrusion 240 and the base, and less vibrational energy is transferred from the base 104 to the gimbal 106.

Alternatively, the flexible rings 152 ', rather than the individual protrusions 240, extend radially outwardly,
An annular flange may be included that is confined between the base 104 'and the annular ring 244 with a viscoelastic cushioning material 230'.

Many implementations of the invention have been described.
Nevertheless, it is understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the cushioning material could be used in other types of known polishing equipment known to those skilled in the art.
For example, polishing systems can use linear belt type pads rather than rotating pads. The polishing apparatus can use either standard non-abrasive polishing pads or fixed polishing pads, and the slurry can have abrasive particles or not. Moreover, the cushioning material can be used in other types of carrier heads. The carrier head can use a rigid support structure or base to hold the substrate instead of a flexible membrane.
A compressible carrier film will be placed on the bottom of the rigid support structure. The retaining ring does not have to contact the polishing pad.

The vibration dampening material is also used in the carrier head at other locations, such as between the retaining ring and the base, or within the base, and is the load bus between the flexible membrane and the housing. Other materials with suitable damping properties will be used to damp vibrations as long as they significantly reduce or prevent the transfer of vibrational energy from one end of the material to the other. Generally, the material can be a viscoelastic material. Further, the cushioning material can be selected from those that do not rebound to their original shape when deformed. In particular, when deformed, the cushioning material is
Rebounds of less than 6 percent of deformation are preferred, but less than 10 percent of deformation must be taken. For example, the cushioning material may be any isodamp C-1000 series insulation damping material, visco-elastic material, soft plastic or a material immediately adjacent to the cushioning material, manufactured by the E-A-R special specialty composite. Any other material having better vibration damping properties may be used. The thickness of the cushioning material will be varied to provide optimum results under operating conditions with different loads, carrier head rotation speeds, polishing pad rotation speeds, cushioning material, etc.

Poor control of the relative motion of the substrate and polishing pad will result from a cushioning material that is too thick, but a thicker cushioning material can be used to improve vibration damping. If the cushioning material is too thin, it will not reduce or prevent the transmission of sufficient vibrational energy, although thinner cushioning materials can also be used.

Accordingly, other embodiments are within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a carrier head.

FIG. 2A is a cross-sectional view of an alternative embodiment of a carrier head.

2B is an exploded view of the cushioning material from the carrier head of FIG. 2A.

Continued front page    (72) Inventor Hyun Chi Chen             California, United States             95050, Santa Clara, Calendar             Live Sharp 1 2419 (72) Inventor Stephen M. Suniga             California, United States             95073, Soukuel, Los Robles               Road 351 (72) Inventor Lima Krishna Cheborg             California, United States             94086, Sunnyvale, Apartment             Ton 1, Grand Far Aveni             551 F term (reference) 3C058 AA07 AB04 CB01 DA13 DA17

Claims (22)

[Claims] 1. A backing assembly having a substrate support surface, a housing connectable to the drive shaft that rotates with the drive shaft about an axis of rotation, and a load path between the backing assembly and the housing. A cushioning material for reducing vibration transmission from the backing assembly to the housing, the carrier head for disposing the substrate on a polishing surface. 2. The carrier head of claim 1, further comprising a gimbal mechanism between the backing assembly and the housing that allows the backing assembly to gimbal with respect to the housing. 3. The carrier head of claim 2, wherein the backing assembly includes a rigid base. 4. The carrier head of claim 3, wherein the backing assembly includes a flexible membrane secured to a rigid base so as to define a pressurizable chamber. 5. The carrier head of claim 3, wherein the backing assembly includes a film compressible on the bottom surface of the base. 6. The carrier head of claim 2, wherein the gimbal mechanism includes a top that connects to the housing, a bottom that connects to the backing assembly, and the cushioning material separates the top from the bottom. 7. The carrier head of claim 6, wherein the cushioning material is attached to at least one of the top and bottom using a pressure sensitive adhesive. 8. The carrier head of claim 6, wherein the cushioning material forms a generally annular body. 9. A gimbal mechanism includes a substantially flat flexure ring that bends in a direction perpendicular to the plane of the flexure ring to gimbal the backing assembly to the housing, and the cushioning material is attached to the flexure ring. The carrier head according to claim 2, 10. The carrier head of claim 2, wherein the cushioning material is in the load path between the gimbal mechanism and the backing assembly. 11. The gimbal mechanism includes a substantially flat flexure ring that bends in a direction perpendicular to the plane of the flexure ring for gimbaling the backing assembly to the housing, and the cushioning material contacts the flexure ring. Item 1
The carrier head according to 0. 12. The carrier head of claim 11, wherein the flexure ring includes a plurality of protrusions extending into the cushioning material. 13. The carrier head of claim 11, wherein the flexure ring includes a flange extending into the cushioning material. 14. The housing provides a bushing and the gimbal mechanism includes a gimbal rod extending to the bushing to prevent the gimbal rod from moving laterally while allowing the gimbal rod to move vertically. The carrier head according to claim 2, wherein: 15. The carrier head of claim 1, wherein the cushioning material is viscoelastic. 16. The carrier head of claim 15, wherein the cushioning material does not rebound to its original shape when deformed. 17. The carrier head of claim 16, wherein the cushioning material is rebound with less than 6 percent of deformation. 18. A polishing pad, a carrier head for positioning a substrate on a polishing surface, the carrier head including a backing assembly having a substrate support surface, and a drive rotating with a drive shaft about an axis of rotation. A chemical mechanical polishing apparatus including a housing connectable to a shaft and a cushioning material in a load path between the backing assembly and the housing to reduce transmission of vibrations from the backing assembly to the housing. 19. The apparatus of claim 18, wherein the carrier head further includes a gimbal mechanism between the backing assembly and the housing to allow the backing assembly to gimbal with respect to the housing. . 20. The apparatus of claim 19, wherein the gimbal mechanism includes a top that connects to the housing, a bottom that connects to the backing assembly, and the cushioning material separates the top from the bottom. 21. The device of claim 19, wherein the cushioning material is a load path between the gimbal mechanism and the backing assembly. 22. The cushioning material is a viscoelastic material.
The device according to.