JP4397176B2 - Vibration damping at carrier head - Google Patents

Description

[0001]
[Cross-reference of related applications]
This application is a continuation-in-part of US patent application Ser. No. 09 / 975,196, filed Oct. 10, 2001, and claims its priority.
[0002]
【background】
The present invention relates generally to chemical mechanical polishing systems and processes.
[0003]
Integrated circuits are typically formed by a series of depositions of conductive, semiconductive, and insulating layers on a substrate (especially a silicon wafer). As a series of layers are successively deposited and etched, the exterior or top layer of the substrate becomes increasingly non-planar. This non-planarized surface presents a problem in the photolithographic step of the integrated circuit fabrication process. In particular, if the maximum height difference between the peak and valley of the non-planarized surface exceeds the depth of focus of the device, the photolithographic device cannot focus on the optical image on the photoresist layer. right. Therefore, there is a need to periodically planarize the substrate surface.
[0004]
Chemical mechanical polishing (CMP) is one accepted method of planarization. Chemical mechanical polishing generally requires mechanical polishing of the substrate with a slurry containing chemically reactive chemicals. During a typical polishing operation, the substrate is held against a rotating polishing pad by a carrier head. The carrier head will also rotate and move the substrate relative to the polishing pad. As a result of the movement between the carrier head and the polishing pad, the abrasive material embedded in the polishing pad or contained in the polishing slurry planarizes the non-planar substrate surface by polishing the surface.
[0005]
The polishing process generates vibrations that will reduce the quality of planarization and damage the polishing equipment. In addition, vibration can create annoying noise.
[0006]
【Overview】
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. Buffer material. The cushioning material reduces the transmission of vibrations from the backing assembly to the housing.
[0007]
Embodiments of the invention will 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 perform gimbal movement 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 film that can be compressed on the bottom surface of the base. The housing will provide a bushing. The gimbal mechanism includes a gimbal rod that extends to the bushing and prevents the gimbal rod from moving sideways, while the bushing will allow the gimbal rod to move vertically.
[0008]
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 generally form an annular body. The gimbal mechanism includes a substantially flat flexible ring that bends in a direction perpendicular to the plane of the flexible ring, gimbals the backing assembly in the housing, and the cushioning material is attached to the flexible ring.
[0009]
The cushioning material will be placed in the load path between the gimbal mechanism and the backing assembly. The gimbal mechanism includes a substantially flat flexible ring that bends perpendicularly to the plane of the flexible ring, gimbals the backing assembly in the housing, and the cushioning material contacts the flexible ring. The flexure ring will include a plurality of protrusions or flanges that extend into the cushioning material.
[0010]
The cushioning material will have viscoelasticity. When deformed, the cushioning material will not rebound to its original shape. For example, the cushioning material will rebound less than 6 percent of deformation.
[0011]
In another aspect, the present invention is directed to a chemical mechanical polishing apparatus that includes a carrier head.
[0012]
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 and drawings, and from the claims.
[0013]
Like reference symbols in the various drawings indicate like members.
[0014]
Referring to FIG. 1, a chemical mechanical polishing (CMP) apparatus includes a carrier head 100 for holding a substrate being polished. A description of a suitable CMP apparatus will be found in US Pat. No. 5,738,574. The contents of which are incorporated herein in their entirety.
[0015]
During polishing, the carrier head 100 pushes the substrate 10 against the polishing pad with a predetermined loading force. At the same time, the motor rotates the carrier head to rotate the substrate. Further, the slider can vibrate the substrate and carrier head 100 laterally across the surface of the polishing pad.
[0016]
The carrier head 100 includes a vibration dampening material to significantly reduce the transmission of vibration energy between adjacent portions to reduce or prevent vibration during polishing. In general, the cushioning material has significantly better vibration damping properties than both adjacent parts of the polishing apparatus, and it is typically made from a hard material (eg, metal). The cushioning material is a viscoelastic material that provides good vibration damping properties and has little or no memory, which is a commercially available insulating cushioning material, 7911 Zionsville Road, Indianapolis, IN 46268 E- Manufactured by C-1002, etc., which is an A-R special composite.
[0017]
As shown in FIG. 1, the carrier head 100 includes a housing 102, a base 104, a gimbal mechanism 106, a retaining ring 110 and a substrate backing assembly 112 (which can also be considered to include the 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 the shaft 107. As described below, a passage 126 extends through the housing 102 for carrier head air control. The housing 102 has a cylindrical bushing 122 adapted to a vertical bore 124 that runs vertically through the housing.
[0018]
The gimbal mechanism 106 includes a gimbal rod 150 and a flexible ring 152. The gimbal rod 150 fits the bushing 122 so that the rod 150 moves freely freely in the bore vertically while the bushing 122 prevents lateral movement of the gimbal rod 150. A flex ring 152 is attached to the flange 220 by a cushioning material 230 at the lower end of the gimbal rod 150 to prevent or reduce transmission of vibration energy through the gimbal ring 220 from the flex ring 152 to the housing 102. The buffer material 230 is 0.06 inches thick. A pressure sensitive adhesive (not shown) adheres the cushioning material 230 to both the housing 102 and the flexible ring 152.
[0019]
A flexible ring 152 (which is a generally flat annular ring) is attached to a generally ring-shaped base 104. The flex ring 152 bends in a direction perpendicular to the plane of the flex ring 152, thereby gimbaling the base 104 relative to the gimbal rod 150 and the housing 102. By allowing the gimbal rod 150 to move vertically within the bore 122, the gimbal mechanism also prevents any lateral movement of the base while allowing the base 104 to move up and down. The buffer material 230 reduces or prevents transmission of vibration energy through the gimbal mechanism 106 from the base 104 to the housing 102.
[0020]
The outer clamp ring 164 secures the outer edge of the rolling diaphragm 160 to the base 104, while the inner clamp ring 162 secures the inner edge of the rolling diaphragm 160 to the housing. Thus, the rolling diaphragm 160 seals 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, leaving an opening 126 in the chamber 108. The openings 126 are connected to a pump (not shown) that raises and lowers the base by moving fluid (eg, air) in and out of the 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.
[0021]
The retaining ring 110 is a generally annular ring that is secured to the base 104. During polishing, fluid is injected into loading chamber 108, thereby creating a pressure within 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.
[0022]
The substrate backing assembly 112 includes a flexible diaphragm 116 that is secured between the retaining ring 110 and the base 104. The inner edge of the flexible 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 flexure diaphragm allows the support plate 170 to move vertically 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 the outer edge thereof.
[0023]
A flexible membrane 118 extends around the lip 178 of the support plate 170 and is fixed between the support plate 170 and the lower clamp 172 to form a substantially disk-shaped lower surface 120. The flexible membrane is formed from a flexible and elastic material (eg chloroprene or ethylene propylene rubber). Alternatively, the flexible diaphragm and flexible membrane may be combined in a single member membrane. The flexible membrane 118, the support structure 114, the flexible diaphragm 116, the volume sealed between the base 104 and the flexible ring 152 defines a chamber 190, and only the opening 250 continues through the gimbal rod 150. A pump (not shown) is connected to the opening 250 to control the pressure in the chamber 190 by injecting fluid into the chamber through the opening 250, thereby causing the downward pressure on the membrane underside 120 to the substrate 10. To control.
[0024]
Referring to FIGS. 2A and 2B, in other embodiments, the gimbal rod 150 ′ and the flexure ring 152 ′ are formed as a single part. Further, this embodiment does not include support structure 114 or flexure 116. Rather, the flexible membrane is connected directly to the base 104.
[0025]
In this embodiment, a cushioning material 230 'is placed between the flex ring 152 and the base 104'. In particular, the flex ring 152 ′ includes a plurality of knurled protrusions 240 that extend radially outward into slots 242 in the base 104 ′. The slot 242 is filled with viscoelastic cushioning material 230 ′ and the top of the slot is closed with an annular ring 244 that is secured to the rest of the base 104 ′. For example, the cushioning material can include a lower layer between the protrusion 240 and the base so that less vibrational energy is transferred from the base 104 to the gimbal 106.
[0026]
Alternatively, rather than the individual protrusions 240, the flexible ring 152 ′ includes an annular flange that extends radially outward and is confined between the base 104 ′ and the annular ring 244 with a viscoelastic cushioning material 230 ′. be able to.
[0027]
A number of implementations of the invention have been described. Nevertheless, it will be 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, the polishing system can use a linear belt type pad rather than a rotating pad. The polishing apparatus can use either a standard non-abrasive abrasive pad or a fixed abrasive pad, and the slurry can have or not have abrasive particles. In addition, the cushioning material can be used in other types of carrier heads. The carrier head can use a rigid support structure or base that holds the substrate instead of a flexible membrane. A compressible carrier film will be placed at the bottom of the rigid support structure. The retaining ring need not contact the polishing pad.
[0028]
The vibration dampening material is also a load bus used at other positions in the carrier head, such as between the retaining ring and the base, or within the base, between the flexible membrane and the housing. Other materials with suitable cushioning properties may be used to damp vibrations as long as they significantly reduce or prevent the transfer of vibration energy from one end of the material to the other. In general, 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 prefers less than 6 percent rebound of deformation, but must take less than 10 percent of rebound. For example, the cushioning material may be any isodamp C-1000 series insulating damping material, viscous-elastic material, soft plastic or material immediately adjacent to the cushioning material manufactured by the E-A-R Special Specialty Composite Any other material having better vibration damping characteristics may be used.
The thickness of the buffer material will be varied to provide optimum results in operating conditions with different loads, carrier head rotation speed, polishing pad rotation speed, buffer material, etc.
[0029]
Although poor control of the relative motion of the substrate and polishing pad will result from a buffer material that is too thick, thicker buffer materials can be used to improve vibration damping. If the buffer material is too thin, it will not reduce or prevent the transfer of sufficient vibrational energy, although thinner buffer materials can also be used.
[0030]
Accordingly, other embodiments are within the scope of the claims.
[Brief description of the 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 buffer material from the carrier head of FIG. 2A.

Claims (19)

A backing assembly having a substrate support surface;
A housing connectable to the drive shaft that rotates with the drive shaft about the axis of rotation;
A buffer material in a load path between the backing assembly and the housing, the buffer material reducing transmission of vibrations from the backing assembly to the housing;
With
The load path is a path for transmitting a load between the backing assembly and the housing;
The buffer material separates a backing assembly side of the load path from a housing side of the load path;
A carrier head for placing a substrate on a polishing surface.   The carrier head of claim 1, further comprising a gimbal mechanism between the backing assembly and the housing that allows the backing assembly to perform gimbal movement with respect to the housing.   The carrier head of claim 2, wherein the backing assembly includes a rigid base.   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. The carrier head of claim 3, wherein the backing assembly includes a compressible film on the bottom surface of the base.   3. The carrier head of claim 2, wherein the gimbal mechanism includes a top connected to the housing and a bottom connected to the backing assembly, and the cushioning material separates the top from the bottom.   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. 7. A carrier head according to claim 6, wherein the cushioning material forms an annular body. Gimbal mechanism, so that the gimbal motion backing assembly housing, the plane of the flexure ring includes a flat flexure ring song that in a direction perpendicular, according to claim 2 in which the buffer material is attached to the flexure ring Carrier head. The carrier head of claim 2, wherein the cushioning material is in a load path for transmitting a load between the gimbal mechanism and the backing assembly. Gimbal mechanism, in order to gimbal motion backing assembly housing, the deflection in the plane of the ring, including a flat flexure ring song that in a direction perpendicular, carrier of claim 10, the deflection ring buffer material is in contact head.   The carrier head of claim 11, wherein the flexure ring includes a plurality of protrusions extending into the cushioning material. The carrier head of claim 11, wherein the flexure ring includes a flange extending to the cushioning material. Housing provides bushing, gimbal mechanism includes a gimbal rod extending bushing, the bushing, while preventing the gimbal rod moves laterally, gimbal rod is adapted to be able to move vertically The carrier head according to claim 2.   The carrier head of claim 1, wherein the cushioning material is viscoelastic.   The carrier head of claim 15, wherein when deformed, the cushioning material is not rebounded to its original shape.   The carrier head of claim 16, wherein the cushioning material is rebounded at less than 6 percent of deformation. With a polishing pad,
A carrier head for placing the substrate on the polishing surface;
Including
The carrier head is
A backing assembly having a substrate support surface;
A housing connectable to the drive shaft that rotates with the drive shaft about the rotation axis;
A gimbal mechanism provided between the backing assembly and the housing, the backing assembly being capable of gimbal movement with respect to the housing;
Cushioning material in a load path between the backing assembly and the gimbal mechanism to reduce transmission of vibrations from the backing assembly to the housing;
Including
The load path is a path for transmitting a load between the gimbal mechanism and the backing assembly.
The buffer material separates the backing assembly side of the load path from the gimbal side of the load path;
Chemical mechanical polishing equipment.   The apparatus of claim 18, wherein the cushioning material is a viscoelastic material.

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