JPH10180626A - Carrier head having suitable material layer for chemical and mechanical grinding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a uniform load to a substrate by providing a carrier including a housing and a storage assembly connected to the housing for housing a suitable material layer and using the suitable material layer for a substrate loading surface. SOLUTION: A carrier head 100 includes a housing assembly 102, a substrate loading assembly 104 and a holding ring assembly 196. The substrate loading assembly 104 includes a thin film 134 made of a flexible, expanded and compressed material such as rubber, and the thin film 134 forms a tightly sealed space 126. The tightly sealed space 126 is filled with a suitable material 132. The suitable material 132 is a non-gaseous material such as silicon and viscous, elastic or viscous-elastic deformed under pressure. A suitable material layer made by filling it with the suitable material 132 is moved or pivotally moved on a substrate 10 to deal with the surface change of a grinding pad 42. The suitable material layer is deformed to coincide with the backside of the substrate 10 and thus a load applied from a loading mechanism to the substrate 10 is uniformly dispersed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] This application was filed by Norman Shendon in 199.
“Chemical Mechanical Po” filed on March 2, 2004
lishing Apparatus with Improved Polishing Contro
No. 08 / 205,276 which is a continuation-in-part of U.S. patent application Ser.
No. 76 is incorporated by Norman Shendon in December 1993.
"Chemical Mechanical Polishin filed on March 27
g Apparatus, U.S. Patent Application Serial No. 08 / 173,846
This is a continuation-in-part application of the specification. The contents of these specifications are incorporated herein by reference.

[0002]

BACKGROUND OF THE INVENTION The present invention relates generally to chemical mechanical polishing of substrates, and more particularly to a carrier head for a chemical mechanical polishing system.

[0003] Integrated circuits are basically formed on a substrate, in particular a silicon wafer, by the sequential deposition of conductive, semiconductor or insulating layers. After each layer is deposited, the layers are etched and the circuit feature
s) is formed. As a series of layers are sequentially deposited and etched, the non-planarity of the outer or top surface of the substrate, ie, the exposed surface of the substrate, increases. Non-planarity of the outer surface poses a problem for integrated circuit fabrication. If the outer surface of the substrate is not flat, the photoresist layer placed thereon will also be uneven.
The photoresist layer is typically patterned by a photolithographic apparatus that focuses a light image on the photoresist. If the outer layer of the substrate is quite uneven, the maximum height difference between the top and the valley of the outer layer can exceed the depth of focus of the imaging device and the outer substrate surface must be properly It becomes impossible to focus.

[0004] Designing new photolithographic equipment with improved depth of focus would be prohibitively expensive. Furthermore, as feature sizes used in integrated circuits become smaller, shorter wavelengths of light must be used, further reducing the effective depth of focus. Therefore,
There is a need to periodically planarize the substrate surface to provide a substantially planar layer surface.

[0005] Chemical mechanical polishing (CMP) is a commonly accepted method of planarization. In planarization methods, the substrate must generally be mounted on a carrier or polishing head. Thus, the exposed surface of the substrate is placed against the rotating polishing head. The carrier applies a controllable load, or pressure, to the substrate to push the substrate against the polishing head. Further, the carrier can be rotated to provide additional movement between the substrate and the polishing head. A polishing slurry including an abrasive and at least one chemically reactive agent is sprayed on the polishing pad to provide a polishing chemical at the pad-substrate interface. The CMP process is quite complex and differs from mere wetsanding. In a CMP process, the reactants in the slurry react with the outer surface of the substrate to form reaction sites. Polishing is caused by interaction with the polishing pad and abrasive particles at the reaction site.

An effective CMP process has a high polishing rate and finishes the substrate surface (eliminating small scale roughness) and flattening (eliminating large scale topology). The polishing rate, finish and flatness are determined by the pad / slurry combination, the relative speed of the substrate and the pad, and the force pushing the substrate against the pad. The choice of polishing pad and slurry combination is usually dictated by the required finish and flatness, as poor flatness and finish can create defective substrates. By providing these conditions, the polishing rate indicates the maximum throughput of the polishing apparatus.

The polishing rate depends on the force pressing the substrate against the pad. In particular, as this force increases, the polishing rate increases. When the carrier head applies a non-uniform load, i.e., when the carrier applies more force to one area of the substrate than the other, the areas with higher pressure polish faster than the areas with lower pressure. Thus, non-uniform loading results in non-uniform polishing of the substrate.

[0008] A further consideration in the manufacture of integrated circuits is process and production stability. To achieve high yields, ie, low defect rates, each successive substrate must be polished under substantially similar conditions. The substrates must each be polished in approximately the same amount so that each of the integrated circuits is substantially identical.
In view of the foregoing, there is a need for a chemical-mechanical polishing apparatus that optimizes polishing throughput while providing the desired flatness and finish. In particular, the chemical mechanical polishing apparatus must have a carrier head that applies a substantially uniform load to the substrate.

[0009]

SUMMARY OF THE INVENTION In one aspect, the present invention relates to a carrier for positioning a substrate on a polishing surface of a chemical mechanical polishing apparatus. The carrier includes a housing and a housing connected to the housing to accommodate the layer of compatible material.
(containment) assembly. The conformable material layer provides a mounting surface for the substrate.

[0010] One embodiment of the present invention may include the following. The storage assembly will include a flexible membrane defining an enclosed space within which the conformable material will be located. A flexible membrane will be attached to the backing member and a flexible connector will connect the backing member to the housing. A flexible connector will form a pressure chamber between the housing and the backing member. The flexible member includes a first flexible thin film portion defining a first enclosed space and a second flexible thin film portion defining a second enclosed space, and is adapted. The material is a first compliant material having a first viscosity and located in a first enclosed space and a second compliant material having a second viscosity and located in a second enclosed space. And will have. A compatible material would be a viscoelastic material such as silicone, gel or urethane. The compliant material will have a durometer measurement of, for example, about 25-35, selected to provide elasticity and normal strain corresponding to the applied load. The storage assembly will include a base member having a recess and a layer of conformable material disposed within the recess to provide a mounting surface. The base member will be removably connected to the carrier head. A retaining ring having approximately the same thickness as the substrate is connected to the mounting surface. A shield thinner than the retaining ring is connected to the base member,
It would protrude beyond the compliant material layer and would surround the retaining ring. The shield will be arranged to prevent the compliant material from being extruded when the substrate is pressed against the polishing surface. The carrier will further comprise a chuck mechanism for attaching the substrate to the mounting surface. The chuck mechanism may include a passage formed through the compliant material layer to the mounting surface, to which a pump may be connected to draw the substrate to the mounting surface. The passage will have a diameter such that the passage does not collapse when the pump applies suction to the passage. The chuck mechanism will have a pocket between the substrate and the layer of compatible material and will aspirate the substrate to the mounting surface.

The advantages of the present invention are described below. The carrier provides a uniform load on the backside of the substrate to uniformly polish the substrate. If the polishing pad tilts, the substrate warps, or has irregularities on the backside of the substrate or underneath the hard surface, the compliant material will deform and redisperse the material.
The conformable layer is chemically inert to the polishing process.
The carrier head can also vacuum chuck the substrate and lift the substrate from the polishing pad.

[0012] Further advantages of the present invention will become apparent from the following description, become somewhat easier to understand from the description, and become apparent from the embodiments of the present invention. The advantages of the invention will be realized by the instruments and combinations particularly pointed out by the appended claims.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the present invention and together with the above general description and the following detailed description, illustrate the principles of the present invention. ing.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. The chemical mechanical polishing (CMP) apparatus 30 generally includes a base 32, which supports a rotating platen 40 and a polishing pad 42. CMP equipment 3
0 further comprises a carrier or carrier head 100, which receives the substrate 10 and places the substrate on a polishing pad. Support assembly 60 connects carrier head 100 to base 32. The carrier head is positioned against the surface of the polishing pad by a support assembly 60.

When the substrate 10 is a disk having a diameter of 8 inches (200 mm), the platen 40 and the polishing pad 42 have a diameter of about 20 inches (508 mm). Platen 40
Is preferably a rotatable aluminum or stainless steel plate, connected to a drive mechanism (also not shown) by a drive shaft (not shown). The drive shaft will also be stainless steel. A drive mechanism, such as a motor and transmission assembly, is located inside the base and rotates the platen and polishing pad. The platen is
Either it will be supported on the base by bearings or the drive mechanism will support the platen. In most polishing processes, the drive mechanism drives the platen 40 from 30 to 200
It rotates at every minute (although lower or higher speeds can be used).

Referring to FIG. Polishing pad 4
2 is a rigid composite, which will have a roughened polishing surface 44. Polishing pad 42 will be attached to platen 40 by adhesive layer 49. The polishing pad 42 has a 50 mil thick hard top layer 46 and a 50 mil thickness.
The mill will have a soft underlayer 48. Upper layer 46
Is preferably a material composed of polyurethane mixed with other fillers. The lower layer 48 is preferably composed of a compressed felt fiber material that has been leached with urethane. Normal, IC-100
A two-layer polishing pad having an upper layer composed of 0 and a lower layer composed of SUBA-4 is available from Rodel of Newark, Del. (Note IC-100).
0 and SUBA-4 are the names of Rodel).

Referring to FIG. A slurry 50 comprising a reactive chemical (eg, deionized water for oxidative polishing), abrasive particles (eg, silicon dioxide for oxidative polishing), and a chemically reactive catalyst (eg, potassium hydroxide for oxidative polishing). Is supplied to the surface of the polishing pad 42. A slurry supply tube or port 52 sprays or otherwise meters the slurry onto the polishing pad. Slurry can also be pumped to the underside of substrate 10 through passages (not shown) in platen 40.

To properly position the carrier head with respect to the polishing pad, the support assembly 60 is provided with a crossbar 62, which extends across the polishing pad. The crossbar 62 is placed above the polishing pad by a pair of opposed upright members 64a, 64b, 66, and a bias piston 68.
One end of the crossbar 62 is connected to the upright members 64a and 64b by hinges 65. The other end of the crossbar 62 is connected to a bias piston 68. The bias piston can move up and down the crossbar 62 to control the vertical position of the carrier head. A second upright member 66 is located adjacent the biasing piston 68 and provides a vertical stop that limits movement below the crossbar.

To place the substrate on the carrier head 100,
Remove the crossbar from the bias piston and move the hinge 65
Rotate the crossbar around the carrier head 1
00 is lifted from the positioning pad. Next, the substrate is placed on the carrier head, and the carrier head is lowered to a position where the substrate 10 faces the polishing surface 44 (see FIG. 3A).

[0020] The support assembly 60 includes a transfer case 70 suspended from the crossbar 62 to controllably orbit and rotate the substrate with respect to the polishing pad. The transfer case 70 includes a drive shaft 72 and a housing 74. The housing 74 includes a fixed inner hub 76 and an outer hub 7.
8 are provided. The fixed inner hub 76 is firmly fixed to the lower side of the crossbar 62 by, for example, a plurality of bolts (not shown). The rotatable outer hub 78 is supported on the fixed inner hub 76 by an upper tapered bearing 77 and a lower tapered bearing 77. These bearings vertically support the rotatable outer hub 78 and allow the rotatable outer hub 78 to rotate with respect to the fixed inner hub. The drive shaft 72 extends through the fixed inner hub 76 and is supported vertically by a tapered bearing 79, the drive shaft 72 being fixed to the fixed inner hub 76.
Can be rotated about.

As described in the above-mentioned US patent application Ser. No. 08 / 173,846, a first motor and transmission assembly 80 is connected to the drive shaft 72 to control the orbital motion of the carrier head. , A second motor and transmission assembly 84 connected to a rotating external hub 78 by pulleys 85 and drive belts 86 and 87 to control the rotational movement of the carrier head. Horizontal cross arm 8
One end of 8 is connected to the lower end of the drive shaft 72. The other end of the cross arm 88 is connected to the top of the second vertical drive shaft 90. The bottom of the second drive shaft 90 fits into the cylindrical recess 112 of the carrier head. Therefore, when the drive shaft 72 rotates,
The second drive shaft 90 and the carrier head 100 move along a track.

The support assembly 60 also includes a rotation adjustment assembly for controlling the rotation speed of the carrier head 100. The rotation adjustment assembly includes a ring gear 94, which is connected to the bottom of the rotating outer hub 78 of the housing 74, and a pinion gear 96 is connected to the second drive shaft 90 directly below the cross arm 88. Ring gear 94 has a toothed inner surface, and pinion gear 96 has a toothed outer surface that engages the toothed inner surface of ring gear 94. When the cross arm 88 pivots, the pinion gear 96 rotates around the inner circumference of the ring gear 94. A pair of mating pins 98 are provided in the pinion gear holes 114 of the phase in the carrier head.
And rotationally secures the pinion gear with respect to the carrier head. Therefore, the rotatable external hub 7
8 is transmitted to the carrier head 100 through a ring gear 94, a pinion gear 96, and a dowel pin 98.

The adjustment assembly allows the rotational and orbital movement of the substrate 10 to be controlled as the user of the CMP apparatus 30 changes both the rotational and orbital components of the carrier head movement. By rotating the rotatable external hub 78 at the same time as rotating the drive shaft 72, the actual rotational movement of the carrier head 100 is controlled. The carrier head 100 and the substrate 10 rotate,
It will perform orbital motion or rotation and orbital motion. The carrier head rotates orbits about 30 to 200 times per minute (rpm).

As the substrate orbits, the polishing pad rotates. Preferably, the orbit radius is less than 1 inch (25.4 mm), and the polishing pad rotates at a relatively low speed, for example, less than 10 rpm, more preferably less than 5 rpm. The orbital movement of the substrate and the rotational movement of the polishing pad are combined to provide a nominal speed of 1800-4800 cm / min on the substrate surface.

The substrate typically undergoes multiple polishing steps, including a main polishing step and a final polishing step. In the main polishing step, the carrier head 100 is about 4 to
10 pounds per square inch (psi) (2812-703)
1 kg / m ² ) (although more or less force may be applied to the carrier head 100).
Add to In the final polishing step, the carrier head 10
0 applies a force of about 3 psi (2109 kg / m ² ).

In general, the carrier head 100 transmits torque from the drive shaft to the substrate to evenly load the substrate against the polishing surface and prevent the substrate from slipping from under the carrier head during the polishing operation. ing.

As shown in more detail in FIG. 3A, the carrier head 100 includes three main assemblies, a housing assembly 102, a substrate loading assembly 104, and a retaining ring assembly 106.
It is.

The housing assembly 102 is generally circular and is adapted to match the circular shape of the substrate being polished. Housing assembly 102 may be machined aluminum. Housing assembly 1
The top surface of 02 has a cylindrical hub 110 with a cylindrical recess 112 and receives a second drive shaft 90. At least one passage 116 is connected from the recess 112 to the bottom of the housing assembly 102.

As shown in FIG. 2, the drive shaft 72 is
With the above-mentioned channel 150, the second drive shaft 90
Has one or more channels 152 for fluid or electrical connection to the carrier head. A rotary coupling 154 at the top of drive shaft 72 connects channel 150 to one or more fluid or electrical lines 156. For example, one of the lines 156 may be a compatible material supply line described below. Another rotary coupling (not shown) of cross arm 88 connects channel 150 of drive shaft 72 to channel 152 of second drive shaft 90. As shown, passage 116 is provided in housing assembly 1.
02 and connects the channel 152 to the substrate loading assembly 104.

As the polishing pad rotates, the polishing pad tends to lift the substrate from below the carrier head.
Therefore, the carrier head 100 is
The retaining ring assembly 106 projects downwardly from the housing assembly 102 and extends around the periphery of the substrate. The retaining ring assembly 106 is attached to the housing assembly 102 with a key-and-keyway assembly 120 and is free to adapt to changes in the height of the polishing surface 44 as the retaining ring assembly rests on the polishing pad. It will be. Inner edge 1 of retaining ring assembly 106
The polishing pad cannot lift the substrate from beneath the carrier head 100 because 22 is capturing the substrate. Retaining ring assembly 106 will be made of a hard plastic material.

A substrate loading assembly 104 is located below the housing assembly 102 in a recess formed by the retaining ring assembly 106. The substrate loading assembly 104 will include a movable carrier plate 124, a thin film 134 defining an enclosed space 126, and a movable carrier film 128. The enclosed space 126 is used for holding ring assembly 106.
Located in a cylindrical recess surrounded by

The movable carrier plate 124 will be a circular stainless steel plate of approximately the same diameter as the substrate. The lower surface of the carrier plate or the lower surface of the housing (if there is no carrier plate) has a surface 130 to which the thin film 134 adheres.

The enclosed space 126 is filled with a compatible material 132. The compliant material 132 is a non-gaseous material that undergoes viscous, elastic or viscoelastic deformation under pressure. Preferably, the compliant material 132 is a viscoelastic material, such as silicone, gel, or other substantially elastic but also viscous material, that redisperses the material under pressure. The pressure applied during polishing is spread fairly evenly across the substrate 10 by the conforming material in the enclosed space 126.

As shown in FIG. 3A, the thin film 134 defines a closed space 126. The thin film is made of a flexible, stretchable and compressible material such as rubber. Thin film 1
34 completely encloses the compliant material 132. Thin film 134
The upper surface 136 is disposed so as to face the surface 130. FIG.
Alternatively, as shown in (B), a closed space may be formed by extending a thin film over the recess below the surface 130 and filling the closed space with a compatible material 132.

The carrier film 128 is formed on the lower surface 13 of the thin film 134.
8 may be attached. The carrier film 128 is formed of a thin circular layer of a porous material such as urethane.
When the carrier film 128 is used, the carrier film 1
Reference numeral 28 is sufficiently thin and flexible, and substantially coincides with the surface of the substrate 10. The mounting surface 14 is provided on the carrier film 128.
2 is provided, and the substrate 10 is removably adhered to the mounting surface 142 by surface tension. If a carrier film is not used, the same effect may be achieved by making the lower surface of the thin film 134 porous instead (see FIG. 5). Carrier film 128 is sufficiently thin and flexible to substantially conform to the surface of substrate 10.

Retaining ring assembly 106 and mounting surface 1
The space defined by 42 is a substrate receiving recess 140
Is provided. When the substrate is placed against the mounting surface 142, the compliant material 132 and the carrier film 128 (if present) are deformed such that the substrate contacts the entire back surface. Carrier head 100 is then lowered so that the substrate contacts polishing surface 44. The load applied to the substrate is transmitted through the conformable material 132.

The polishing surface 44 will not be flat, but will have, for example, an inclined shape. The underside or surface 141 of the carrier plate 124 and the housing assembly 102 will also be uneven. The polishing pad will be tilted with respect to the carrier head. In addition, the back surface of substrate 10 will have surface irregularities. The substrate may be twisted. The compliant material 132 ensures that the carrier load applied to the substrate is evenly distributed over both large scale effects (eg, polishing pad tilt) and small scale effects (eg, surface irregularities on the backside of the substrate). Compliant material 132 conforms to the substrate surface as well as surface 130. That is, the compliant material inside the thin film 134 redisperses the material to conform to the surface irregularities and surface 130 on the backside of the substrate. Since the compliant material comes into contact with the substrate over the entire back surface and the compliant material has a uniform density,
A uniform load over the back side of the substrate is ensured. Further, the compliant material 132 can flow and deform. This allows the substrate to tilt with respect to the housing assembly 102 to follow the shape of the polishing pad. In summary, the compliant material ensures that the carrier head 100 applies a uniform load on the polishing surface 44 to the substrate.

As the carrier head 100 rotates at high speed, centrifugal forces will tend to push the compliant material in the enclosed space outwardly toward the edges of the carrier head. This tends to increase the density of compliant material near the perimeter of the enclosed space. As a result, compliant material near the edges of the enclosed space will tend to be less compressive than in the center, and non-uniform loads will be applied to the substrate.

To prevent this non-uniform loading, the enclosed space 126 is connected to a supply 158 by passages 116, channels 150 and channels 152 and a compatible material supply line 156. Source 158 may provide a compliant material at a constant pressure to enclosed space 126.
As a result, the carrier head 100 rotates and the compatible material 1
32 is forced toward the edge of the enclosed space, source 1
58 provides further conformable material in the center of the enclosed space,
Maintaining a substantially uniform distribution of the compliant material through the enclosed space 126. This uniform distribution of compliant material ensures uniform polishing of the center and edges of the substrate.

Source 158 can also be used to control the viscosity of compliant material 132. By increasing the pressure of the compliant material, the density of the compliant material 132 can be increased. As the density of the compliant material 132 increases, the viscosity decreases.

The minimum pressure from source 158 must overcome the load applied to the substrate by the carrier head, which causes the compliant material to return through passage 116. When the carrier head stops rotating, the conformable material is evenly distributed across the membrane 134. Excess compliant material is flushed back through passageway 116, passageway 150 and passageway 152 toward source 158.

In another embodiment, the compliant material 132 may be a material, such as rubber, that is sufficiently rigid that it does not flow under the influence of centrifugal force. In this embodiment, the compliant material 13
2 does not change significantly when the carrier head 100 rotates. Accordingly, a compatible material source 158 is not required.

As shown in FIG. 4, the substrate loading assembly 104 includes a plurality of compartments or enclosed spaces 1.
60 and 162 may be provided. Closed space 160 and 1
62 is defined by two or more thin film portions. The thin film portions may be separate and distinct thin films or different portions of a single thin film. Sealed space 16
0 is a circular plate shape, is located above the central portion of the mounting surface 142, and the closed space 162 may be an annular ring surrounding the closed space 160. Enclosed spaces 160 and 162 include compliant materials 164 and 166, respectively. Compatible materials 164 and 166 have different viscosities. By choosing matching materials 164 and 166 of relative viscosity, excessive polishing of the substrate edges can be avoided and more uniform polishing of the substrate is achieved. Each enclosed space will be connected to a source (not shown) by passage 168.

Referring to FIG. Carrier head 10
The 0 is held in a vertically fixed position by the support assembly 60 (see FIG. 3A), and a force will be applied to the substrate 10 by the carrier head. In this embodiment, the substrate loading assembly 104 is a bellows 1
70 and other flexible connectors. Bellows 170
Connects the substrate backing member 174 to the housing assembly 10.
2 is connected to the bottom surface 173. Bellows 170 are extensible, and substrate backing member 174 is vertically movable with respect to housing assembly 102. Bellows 170
Form a pressure chamber 176. The pressure chamber 176 is maintained at a negative or positive pressure by a pressure source or a vacuum source (not shown).
8 are connected. A thin film 134 is attached to the bottom surface of the substrate backing member 174. Chamber 176
Is applied to the compliant material 132, pushing the substrate against the polishing pad. Therefore, the flexible connector 170 functions as a load mechanism, and the bias piston 68
Instead of

The closed space 126 is connected to a supply source as shown in the embodiment of FIG. Flexible conduit 182 (which may be a plastic tube) connects passage 180 of substrate backing member 174 to passage 116 of housing assembly 102 for that purpose. Flexible conduit 182
The location where the two connect the passages 180 and 116 are sealed by suitable engagement to prevent leakage of the compliant material 132 into the pressure chamber 176.

Referring to FIG. In another embodiment, one or more substrates 10 are chemically mechanically polished (CMP).
Polished by the device 220. A complete description of CMP apparatus 220 was filed on October 27, 1996 by Perlov et al., Entitled "CAROUSEL PROCESSING SYSTEM FOR CHEMI.
CAL MECHANICAL POLISIHING ", which can be found in commonly assigned U.S. patent application Ser. No. 08 / 546,336, the disclosure of which is incorporated herein by reference.

The CMP device 220 has the table surface 22
3 and includes a lower device base 222 with a removable upper outer cover (not shown). Table surface 223
Supports a continuous polishing station 225a, 225b and 225c, and a transfer station 227. The transfer station 227 is generally arranged in a square with three polishing stations 225a, 225b and 225c. The transfer station 227 receives the individual substrates 10 from a loading device (not shown),
It has a plurality of functions such as cleaning the substrate, loading the substrate on the carrier head (described later), receiving the substrate from the carrier head, cleaning the substrate again, and finally transferring the substrate to a loading device.

Each of the polishing stations 225a-225
c includes a rotating platen 230 and the rotating platen 23
A polishing pad 232 is placed on the reference numeral 0. The substrate 10 is an 8 inch (200 mm) diameter disk, and the platen 230 and polishing pad 232 are about 20 inches in diameter. Rotating platen 230 is preferably a rotatable aluminum or stainless steel plate and is connected to a platen drive motor (not shown) by a stainless steel platen drive shaft (not shown). In a typical polishing process, the drive motor rotates the platen 230 30 to 200 times per minute (higher or lower rotational speeds can be used).

Referring to FIG. Polishing pad 232
Is a composite material having a roughened polishing surface 234.
The polishing pad 232 is attached to the platen 23 by the adhesive layer 239.
It may be attached to 0. The polishing pad 232 has a thickness of 5
0 mil hard upper layer 236 and 50 mil thick soft lower layer 2
38. Upper layer 236 is preferably a material composed of polyurethane mixed with other fillers. The lower layer 238 is preferably composed of a compressed felt fiber material leached with urethane.
A conventional two-layer polishing pad having an upper layer composed of IC-1000 and a lower layer composed of SUBA-4 is available from Rodel, Newark, Del. (Note that IC-1000 and SUBA-4 are Rodel, Inc.). Name).

Returning to FIG. Each polishing station 22
5a-225c may further include an associated pad adjustment device 240. The pad adjustment device 240 has a rotatable arm 242, and the adjustment head 2 that rotates independently
44 and an associated cleaning dish 246. The conditioner properly maintains the condition of the polishing pad to effectively polish any substrate pressed against the polishing pad during rotation.

Reactive chemicals (eg, deionized water for oxidative polishing) and abrasive particles (eg, silicon dioxide for oxidative polishing)
And a slurry 250 containing a chemically reactive catalyst (eg, potassium hydroxide for oxidative polishing) is supplied to the surface of the polishing pad 232 by a slurry supply tube 252. Sufficient slurry is provided to wet the entire polishing pad 232. Two or more intermediate cleaning stations 25
Polishing station 22 where 5a and 255b are adjacent
5a, 225b and 225c. The cleaning station rinses the substrate as it is transferred from one polishing station to another.

A rotary multi-head conveyor (rotable mu)
An lti-head carousel 260 is disposed on the lower device base 222. The rotary conveyor 260 is supported by a center post 262, and the center post 2
It is rotated above 62 by a rotary conveyor motor assembly disposed within a base 222 about a rotary conveyor axis 264. The center post 262 supports the rotary conveyor support plate 266 and the cover 268.
The rotary multi-head conveyor 260 has four carrier head systems 270a, 270b, 270c and 27.
0d. Three carrier head systems receive and support the substrates, and polishing stations 225a-225.
Pressing against the polishing pad 232 of the platen 230 of FIG. One of the carrier head systems receives the substrate and sends it to the transfer station 227.

Four carrier head systems 270a-
270d is mounted on a rotary conveyor support plate 266 at equal spaced angles about a rotary conveyor axis 264. The center post 262 allows the rotary conveyor motor to rotate the rotary conveyor support plate 266 and orbit the carrier head systems 270a-270d and the attached substrate about the rotary conveyor axis 264.

Each carrier head system 270a-
270d includes a polishing or carrier head 300. Each of the carrier heads 300 individually rotates about its own axis and individually oscillates laterally within a radial slot 272 formed in a rotating conveyor support plate 266. Carrier drive shaft 274 connects carrier head rotation motor 276 to carrier head 300 (shown with １ ／ of cover 268 removed). Each head has one carrier drive shaft and motor.

Referring to FIG. The cover 268 of the carousel 260 has been removed and the carousel support plate 266 has four carrier head systems 270a-27.
0d is supported. The carousel support plate is provided with four radial slots 272, which are oriented at 90 ° intervals and extend radially. The radial slot 272 may be closed at the end (as shown) or open at the end. The top of the support plate supports four grooved carrier head support sliders 280. Each slider 280 is aligned along one of the radial slots 272 and is free to move with respect to the carousel support plate 266 along a radial path. Two linear bearing assemblies are provided in each radial slot 27
2 and carry each slider 280.

As shown in FIGS. 7 and 8, each linear bearing assembly is fixed to a rail 282 fixed to a rotary conveyor support plate 266 and a slider 280,
It has two hands 283 (only one of which is shown in FIG. 8) for gripping the rails. The two bearings 284 separate the hand 283 from the rail 282, respectively, to provide free and smooth movement therebetween. Thus, the linear bearing assembly allows the slider 280 to move freely along the radial slot 272.

The bearing stop 285 is connected to one of the rails 282.
Fixed to the two outer ends to prevent the slider 280 from accidentally falling off the end of the rail. One of the arms of each slider 280 is provided with a threaded receiving cavity or nut, not shown, which is fixed to the distal end of the slider. The threaded cavity or nut receives a worm gear lead screw 286 driven by a slider radial vibration motor 287 mounted on a rotating conveyor support plate 266. Motor 287 is lead screw 2
Turning 86 moves the slider 280 in the radial direction. The four motors 287 are individually operable and move the four sliders individually along the radial slots 272 of the carousel support plate 266.

The carrier head assembly or system includes a carrier head 300, a carrier drive shaft 274, a carrier motor 276, and an enclosing non-rotating shaft housing 278 each secured to each of the four sliders. Drive shaft housing 27
8 holds the drive shaft 274 by a set of two lower ring bearings 288 and a pair of upper ring bearings 289. Each carrier head assembly is assembled away from the polishing device 220 and slid unsqueezed between the arms of the slider 280 in the radial slot 272 of the rotating conveyor support plate 266,
Then, the slider is tightened so as to grip it.

The rotary coupling 290 on top of the drive motor 286 has two or more fluid or electrical lines 292.
Are connected to two or more channels 294 of the drive shaft 274. Channel 294 pneumatically powers carrier head 300, as described in further detail below,
The substrate is vacuum chucked to the bottom of the carrier head and used to operate a retaining ring against the polishing pad.

During actual polishing, for example, three carrier heads of the carrier head systems 270a to 270d
It is located above each position of the carrier head polishing stations 225a-225c. The carrier head 300 lowers the substrate to contact the polishing pad 232,
Slurry 250 functions as a medium for chemical mechanical polishing of a substrate or wafer. The carrier head 300 applies a uniform load on the polishing pad to the substrate.

The substrate typically undergoes multiple polishing steps, including a main polishing step and a final polishing step. In the main polishing step, which typically takes place at station 225a, carrier head 300 is about 4-10 pounds per square inch (psi) (2812-7031 kg / m ² ).
Is applied to the substrate 10. At subsequent stations, the carrier head 300 will be subjected to more or less force. For example, in the final polishing step usually performed in the station 225c, the carrier head 300
Applies a force of about 3 psi (2109 kg / m ² ). The carrier motor 76 moves the carrier head 300 to about 30 to 2
Rotate 00 times every second. Platen 230 and carrier head 300 can rotate at substantially the same speed.

In general, the carrier head 300 holds the substrate against the polishing pad and evenly distributes downward pressure across the back of the substrate. The carrier head also transmits torque from the drive shaft to the substrate to prevent the substrate from slipping from below the carrier head during polishing.

FIG. 9A will be described. The carrier head 300 includes a housing assembly 302, a loading mechanism 304, and a base assembly 306.
Drive shaft 274 is connected to housing assembly 302. Loading mechanism 304 connects housing assembly 302 to base assembly 306. The loading mechanism applies a load, ie, downward pressure, to the base assembly 306. The base assembly 306 transmits downward pressure from the loading mechanism 304 to the substrate 10 and pushes the substrate against the polishing pad. The base assembly 306 includes a conformable layer 308 to evenly distribute downward pressure across the backside of the substrate.
Each of these components is described in more detail below.

[0064] Housing assembly 302 may be formed of aluminum or stainless steel. The housing assembly generally corresponds to the circular shape of the substrate being polished in a circular shape. The top surface of the housing assembly
A cylindrical hub 320 having a threaded neck 322 is provided. In order to connect the drive shaft 274 to the carrier head 300, within the hub 320 and the flange 296, 2
One dowel pin 324 will be inserted into the dovetail pinhole of the phase. Accordingly, a threaded peripheral nut 298 is threadably attached to the threaded neck 322 to secure the carrier head 300 to the drive shaft 274. As drive shaft 274 rotates, dowel pin 324 transmits torque to housing assembly 302, causing the carrier head to rotate about the same axis as the drive shaft.

At least two conduits 326 and 328
Extend through the hub 320. Each channel 29
One conduit for four would be in drive shaft 274. When the carrier head 300 is mounted on the drive shaft 274, the dowel pins align the carrier head and the conduits 326 and 328 connect the channels 294. An O-ring (not shown) is attached to hub 320 and conduit 326
And 328 to form a fluid tight seal between the channel and the subsequent conduit.

The loading mechanism 304 forms a vertically movable seal between the housing assembly 302 and the base assembly 306 and defines a pressure chamber 330. Gas, such as air, is drawn into and out of pressure chamber 330 through conduit 326 and controls the load applied to base assembly 306. When air is drawn into the pressure chamber 330, the base assembly 3
06 is pressed downward so that the substrate 10 contacts the polishing pad 232. As the air is evacuated from the pressure chamber 330, the base assembly is lifted upward to move the substrate away from the polishing pad 232.

The loading mechanism 304 is a cylindrical bellows 3
32, the bellows 332 may be bolted or secured to the housing assembly 302 and the base assembly 306 to form a pressure chamber 330. Bellows 332 are stainless steel cylinders that expand or contract depending on whether gas is supplied to or removed from pressure chamber 330. Bellows 332
May include an upper support plate 334 and a lower support plate 336, each plate being bolted or secured to the housing assembly 302 and the base assembly 306. The cylindrical seal 338 is mounted on the rim 31 of the housing 302.
0 and a circumferential groove 339 of a wall portion 318 extending upwardly of the base assembly 306. Seal 338 surrounds and seals bellow 332 with slurry 2
50 protects against the effects of corrosion. As the housing assembly 302 rotates, the bellows 332 transmits torque from the housing assembly to the base assembly,
The base assembly is also rotated. However, because the bellows are flexible, the base assembly 306 can pivot with respect to the housing assembly about an axis parallel to the surface of the polishing pad and remain substantially parallel to the polishing pad surface. It is.

The base assembly 306 includes a rigid backing fixture or plate 350 and a removable module 352, which are mounted below the backing plate 350. Backing plate 350 is generally disk-shaped to conform to substrate 30, and may be a metal such as aluminum or stainless steel. Module 352 includes rigid support fixture or cup 354, conformable layer 308, annular shield ring 3
60 and an annular retaining ring 362. Each of these members is described in detail below.

The module 352 is detachably attached to the backing plate 350 by any attachment mechanism such as a combination of bolts, screws, keys and key grooves, a vacuum chuck or a magnet. Thus, module 35
2 can be removed and replaced if damaged or worn. Further, the polishing parameters can be changed by replacing the module 352. For example, different modules may incorporate matching layers having different durometer measurements. Different modules can also have different retaining ring widths or retaining ring heights. The height and width of the retaining ring affect the polishing rate near the edge of the substrate. The features of these modules are selected to provide optimal polishing characteristics.

The cup 354 may be formed of aluminum or stainless steel and have a downwardly projecting outer lip or rim 356 surrounding the recess. The conforming layer 308 is located in the recess, and the bottom surface of the conforming layer is substantially flush with the bottom surface of the rim 356. About 1 recess
/ 8 to 1/4 inch deep.

The conformable layer 308 is made of a viscoelastic material and has substantially the same density. The conformable layer 308 is elastic, ie, returns to its original form when the applied load is removed. The conformable layer 308 is slightly compressible. In addition, the conformable layer 308 experiences normal strain, ie, redistributes the material in a direction perpendicular to the applied load. The durometer measurement of the conforming layer must be carefully selected. If the durometer measurement is too low, the material will lack elasticity. On the other hand, if the durometer measurement is too high, the material will not experience normal strain. The conformable layer 308 has a durometer measurement of about 15-25 on the Shore scale. The conformable layer 308 preferably has a durometer measurement of about 21 on the Shore scale. The compliant material will have an adhesive surface and will adhere to the wall of the cup 354. In addition, it must be chemically inert to the polishing process and resistant to heat. A suitable compatible material is a urethane material, Ze, Pennsylvania
Available from Pittsburgh Plastics of lienopal. Module 352 is manufactured by delivering liquid urethane to cup 354 and crosslinking to form layer 309.

Referring to FIG. The conformable layer 308 allows the substrate 10 to move or pivot to accommodate changes in the polishing pad surface. The conformable layer 308 deforms to match the back side of the substrate 10 and the loading mechanism 304
To evenly distribute the load on the substrate. For example, the substrate 10
If is distorted, the conformable layer 308 actually conforms to the shape of the distorted substrate.

The thin sheet 358 of low friction material is applied to the conforming layer 3
08 to provide a low friction substrate mounting surface 364. Sheet 358 is a 7 mil thick urethane film with a durometer reading of about 8 on the Shore scale.
3. The sheet 358 is such that the compliant material layer 308
0, but it can prevent the substrate from sticking to compatible materials. Sheet 358
Is sufficiently thin that substrate 10 can be considered to be in direct contact with conformable layer 308.

Referring to FIG. 9A. Module 352 also includes shield ring 360 and retaining ring 362, as previously described. Shield ring 360
Is formed of a hard material such as aluminum or stainless steel, and is disposed below the conforming layer 308, and the bottom surface of the rim 356 and the conforming layer are substantially at the same height. The shield ring 360 holds the conformable layer 308 with the recess in the cup 354 when the substrate 10 is under load. The shield ring 360 is appropriately fixed to the rim 356 by screws or bolts (not shown) or the like.

The retaining ring 362 is an annular hard ring, and is disposed inside the circumference of the shield ring 360. The retaining ring 362 will be directly adhered to the conformable layer 308. The retaining ring 362 is formed of a hard plastic or ceramic material. Retaining ring 362
Because is separated from shield ring 360 by a small gap “r”, retaining ring 362 can move or pivot, adjusting for changes in the vertical height of the surface of polishing pad 232. In operation, the substrate 10 holds the retaining ring 3
Fits within the circular recess defined by 62 and is adjacent the mounting surface 364 of the conforming layer. Retaining ring 362
And the substrate 10 is substantially the same thickness, and the retaining ring 362 also contacts the polishing pad 232. Shear forces created by the relative speed between the substrate 10 and the polishing pad 232 tend to push the substrate from underneath the carrier head 300. The retaining ring 362 prevents the substrate 10 from moving from under the base assembly 306.

Referring to FIG. 9B. In this other embodiment, similar parts are the same as those described above,
Loading mechanism 304 'would include a flexible membrane 340 instead of a bellows. Flexible membrane 340 is an annular sheet of silicone having a thickness of about 60 mils and has an inner edge 342 and an outer edge 344. Inner edge 342
The inner clamping ring 346 and the base assembly 30
6 ', and outer edge 344 is clamped between outer clamping ring 348 and housing assembly 302'. A clamping ring attaches the flexible membrane to the housing assembly and the base assembly, forming a pressure chamber 330 '.
The flexible membrane 340 acts as a diaphragm and is wound and stretched by a vertical distance across the pressure chamber 330 '.

The housing assembly 302 ′ has two opposing flanges 314 and projects downward from the rim 310. Each flange 314 will have a rectangular slot 315. Torque pin 31
6 extend through each rectangular slot 315;
It is secured to a receiving recess 317 in a wall 318 'extending above the backing plate 350 of the base assembly 306'. The width of the rectangular slot 315 corresponds to the width of the torque pin 316, and the pin does not move horizontally within the slot. Drive shaft 274 is connected to housing assembly 30.
Upon rotation of 2 ', torque pin 316 transfers torque from the housing assembly to the base assembly. The height of the rectangular slot 315 is higher than the height of the torque pin 316 so that the pin can move vertically within the slot. Thus, the base assembly 306 'must rotate with the housing assembly 302', but is free to move vertically with respect to the housing assembly.

As mentioned above, the carrier head 300 will lift the substrate 10 from the polishing pad 232 and move the substrate from one polishing station to another. Further, the substrate will be ejected from carrier head 300 and returned to transfer station 227 (see FIG. 6). Specifically, the carrier head 300 will vacuum chuck or evacuate the substrate to the mounting surface 364. This is described below.

The carrier head is provided with a plurality of fluid lines such that a gas, such as air, flows into or out of the base assembly 306 to vacuum chuck or evacuate the substrate. Base assembly 306 and housing assembly 302 can move vertically with respect to each other, and a flexible fluid conduit is used to couple conduit 328 to passage 370 of backing plate 350. As shown in FIG. 9A, the flexible fluid conduit is a metal bellow 372
Will. The metal bellows can extend to match the distance it extends across the chamber 330. Alternatively, as shown in FIG. 9 (B), the flexible fluid conduit may be a plastic tube 37 located within chamber 330 '.
4 may be used. The plastic tube is, for example, 1/2,
It is wound in 3/4 or full turn. As the base assembly 306 'moves relative to the housing assembly, the tube is unwound or unwound and the chamber 330'
Match the distance across.

Referring to FIG. In one embodiment, passage 370 is a passage 3 of one or more cups 354.
76. In addition, a vacuum chuck passage 380 extends from the passage 376 in the cup 354 through the conformable layer 308 to the mounting surface 364. Each vacuum chuck passage 380 is simply a hole in the conformable layer. The holes are large enough not to collapse when a vacuum is applied, but small enough to collapse when a load is applied to the substrate.

Pump 382 is mounted through fluid line 292, channel 294, conduit 328, conduit 372, passage 370, passage 376 and vacuum chuck passage 380.
It is connected to the. Vacuum is applied to passage 3 by pump 382
When applied to 80, the substrate 10 is vacuum chucked. When the air is forced into the passage 380 by the pump 382, the substrate 10 is discharged from the mounting surface 364.

Referring to FIG. As the substrate 10 is placed and loaded against the polishing pad 232, the conformable layer 308 is compressed and the vacuum chuck passage 380
Crush. Thus, the passage does not substantially affect the load distribution over the backside of the substrate. When the load is removed, conformable layer 308 returns to its normal state and vacuum chuck passage 380 reopens. Each vacuum chuck passage 380
Is approximately 1/8 to 1/1 of 1 inch (25.4 mm) in diameter.
Must be 4.

Referring to FIGS. 12A and 12B, FIG. In another embodiment, the substrate 10 is vacuum chucked to the carrier head 300 by forming a vacuum pocket.
As shown in FIG. 12A, the module 352 includes a vertically movable disk 390. The matching layer 308 is a disc 390
Will be adhered to. The diameter of the disc 390 will be smaller than the diameter of the substrate and will be connected to the drive mechanism of the air cylinder 392. Air cylinder 392 is cup part 3
The air cylinder 392 is powered by a pump 382. The pump is connected to the air cylinder by flexible conduits, passages 370 and 376. The driving mechanism of the air cylinder 392 is as follows.
A first position where the disk is at the same height as the bottom surface 394 of the base 378 of the cup portion 354 (see FIG. 12A), and a second position where the disk is attracted upward from the substrate. Between the discs 390. In the second position, the portion of the compliant layer 308 of the disc is pulled upward. Compatible layer 30
As the edges of 8 remain in contact with substrate 10, the center of conforming layer 308 is pulled away from the center of substrate 10 and a vacuum pocket 398 is formed between the substrate and the conforming layer. The vacuum pocket vacuum chucks the substrate to the carrier head.

The conformable layer according to the present invention is described in “CARRIER HEAD D” filed Apr. 24, 1996 by Zuniga et al.
ESIGN FOR A CHEMICAL MECHANICAL POLISHING APPARATU
No. 08 / 637,208, assigned to the assignee of the present application, and the carrier head design, the entire contents of which are incorporated herein by reference. For a variety of other carrier head designs.

Referring specifically to FIG. Such a carrier head 400 includes a housing assembly 402,
Base assembly 404 and retaining ring assembly 40
6 is provided. A conforming layer 408, having a composition and structure similar to the conforming layer described above, is adhered or attached to surface 418 of base assembly 404 to provide substrate mounting surface 410.
Will be provided.

The present invention has been described with reference to a preferred embodiment. However, the invention is not limited to the described and described embodiments. Rather, the scope of the present invention is limited by the appended claims.

[Brief description of the drawings]

FIG. 1 is a simplified perspective view of a chemical mechanical polishing apparatus.

FIG. 2 is a cross-sectional view of a support assembly, a carrier head, and a polishing pad of the chemical mechanical polishing apparatus of FIG.

FIG. 3A is a simplified cross-sectional view of a carrier head and a polishing pad of the chemical mechanical polishing apparatus of FIG. 1, and FIG.
FIG. 9 is a simplified sectional view of a modified example of the carrier head.

FIG. 4 is a simplified cross-sectional view of a carrier head having a plurality of enclosed spaces filled with a compatible material.

FIG. 5 is a simplified sectional view of a carrier head having a loading mechanism.

FIG. 6 is a developed perspective view of the chemical mechanical polishing apparatus.

FIG. 7 is a simplified plan view of the rotary conveyor with the upper housing removed.

8 is a cross-sectional view of the rotary conveyor of FIG. 7 taken along line 8-8.

FIG. 9A is a simplified cross-sectional view of a carrier head comprising a bellows and a compliant material layer according to the present invention, and FIG.
FIG. 4A is a view showing the carrier head of FIG.

FIG. 10 is an enhanced cross-sectional view of the substrate in contact with the compatible material layer of the carrier head of FIG. 9 (A) or (B).

FIG. 11A is a simplified cross-sectional view of a carrier head according to the present invention illustrating a vacuum chuck line of a compliant material layer, and FIG. FIG. 4 is a view of the carrier head in a separated state (A).

FIG. 12A is a simplified cross-sectional view of a carrier head according to the present invention incorporating a vertically movable cylinder to form a vacuum pocket, and FIG. 12B is a view in which the vertically movable cylinder forms a vacuum chuck. It is a figure of (A) of the arranged carrier head.

FIG. 13 is a simplified sectional view of another embodiment of the carrier head of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tungan Chan United States, California, Saratoga, Dehavilleland Drive 19393 (72) Inventor John Prince United States of America, California, Los Altos, Quail Meadow 1925 (72) Inventor Shamowill Shamowilian United States, California, San Jose, Washoe Drive 1256 (72) Inventor Nome Shendon United States of America, California, San Carlos, Northern Avenue 34

Claims (22)

[Claims] 1. A carrier for positioning a substrate on a polishing surface in a chemical mechanical polishing apparatus, said housing for holding a housing and a layer of compatible material providing a mounting surface for the substrate. A storage assembly connected to the
Carrier with. 2. The carrier of claim 1, wherein the storage assembly includes a flexible membrane defining an enclosed space, and the compliant material layer is disposed within the enclosed space. 3. The carrier of claim 2, wherein a flexible film is attached to the backing member, and a flexible connector connects the backing member to the housing. 4. The carrier head according to claim 3, wherein a flexible connector forms a pressure chamber between the housing and the backing member. 5. The flexible thin film section defines a first flexible thin film portion defining a first sealed space, and the second flexible thin film portion defines a second sealed space. A thin film portion, wherein the compatible material has a first viscosity and is disposed in the first enclosed space; and a second compatible material having a second viscosity and is disposed in the second enclosed space. 3. The carrier head of claim 2, including a second compliant material disposed. 6. The carrier according to claim 1, wherein said compatible material is a viscoelastic material. 7. The carrier head according to claim 6, wherein said compatible material is selected from the group comprising silicone and gels. 8. The carrier of claim 6, wherein the conformable material has a durometer measurement selected to provide both elastic and normal strain in response to an applied load. 9. The carrier of claim 8, wherein the durometer measurement of the compliant material is about 25-35. 10. The carrier of claim 9, wherein said compatible material is substantially pure urethane. 11. The carrier of claim 1, wherein the storage assembly includes a base member having a recess, and a layer of conformable material is disposed in the recess to provide the mounting surface. 12. The carrier according to claim 11, wherein the base member is detachably connected to the carrier head. 13. The carrier according to claim 11, further comprising a retaining ring connected to the mounting surface. 14. The carrier of claim 13, wherein said retaining ring is approximately the same thickness as said substrate. 15. The carrier of claim 14, further comprising a shield connected to the base member and projecting beyond a portion of the compliant material layer to surround the retaining ring. 16. The carrier of claim 15, wherein said shield is thinner than said retaining ring. 17. The carrier of claim 11, further comprising a shield ring connected to the base member and protruding beyond a portion of the compliant material layer. 18. The carrier of claim 17, wherein the shield is positioned to prevent the compliant material from being extruded when a substrate is pressed against the polishing surface. 19. The carrier according to claim 1, further comprising a chuck mechanism for attaching the substrate to the mounting surface. 20. The chuck mechanism includes a passage formed through the compliant material layer to the mounting surface, and a pump for suctioning the substrate to the mounting surface is connected to the passage. A carrier according to claim 19. 21. The carrier of claim 20, wherein said passage has a diameter such that said passage does not collapse when said pump draws said passage. 22. The carrier of claim 21, wherein the chuck mechanism includes a pocket between the substrate and the conformable layer for suctioning the substrate to the mounting surface.