JPH09168968A - Design of carrier head of chemical mechanical polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the contamination or breakage of a base by providing a gimbal mechanism for connecting a housing to a base in the rotatable state. SOLUTION: A gimbal mechanism 258 is in a 'state receiving no load', or a down direction force extending from a housing assembly 252 to a base assembly 250 through the gimbal mechanism 268 is not given thereto. However, the gimbal mechanism 258 transmits loads of all sides such as the shearing force by the frictional force between a base 10 and a polishing pad 120 to the housing assembly 252, and never influences on the non-uniformity of pressure to the base 10. Further, the gimbal mechanism 258 holds the base assembly 250 to rotate around the same axis as a driving shaft 184.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art The formation of integrated circuits on a silicon wafer is typically performed by successively depositing conductive layers, semiconductor layers and insulating layers on a substrate, especially on a silicon wafer. After each layer is deposited, the layer is etched to form the features of the circuit. By successively depositing and etching a series of layers, the outer or top surface of the substrate, ie, the exposed surface of the substrate, becomes increasingly non-planar. This occurs because the distance between the outer surface and the underlying substrate is largest in the region where etching is least likely to occur and is smallest in the region where most etching occurs. For underlayers with a single pattern, this non-planar surface has a series of peaks and troughs, and the difference in height between the highest and lowest troughs is 7,000 to 10,000.
It will be about Angstrom. In lower layers with multiple patterning, the height difference between peaks and valleys becomes even more pronounced,
It can reach up to a few microns.

This non-planar outer surface represents a problem in integrated circuit manufacturing. If the outer surface is not flat, when patterning the photoresist by the photolithography technique, it is impossible to accurately focus the photolithography apparatus on the uneven surface.
It may not be suitable. Therefore, it is necessary to regularly planarize the surface of this substrate to planarize the surface. The planarization actually polishes the non-planar outer surface to remove any of the conductive layers, semiconductor layers or insulating layers to form a relatively flat and smooth surface. Subsequent to planarization, additional layers may be deposited on top of the outer layer to form interconnect lines between features, or the outer layer may be etched to provide vias to the underlying features. Passages) may be formed.

Chemical mechanical polishing is one of the accepted methods of planarization. This planarization method typically requires mounting the substrate on a carrier or polishing head, exposing the surface of the substrate to be polished. Then, the substrate is applied to the rotating polishing pad. Further, the carrier head may be rotated to provide more movement between the substrate and the polishing surface. Further, a polishing slurry containing an abrasive and at least one chemically reactive agent may be spread over the polishing pad to provide an abrasive chemical solution at the interface between the pad and the substrate.

Important factors in the chemical mechanical polishing process are the finish (roughness) of the substrate surface, the flatness of the substrate surface (there is no large three-dimensional shape), and the polishing rate. Inappropriate flatness and roughness cause substrate defects. The polishing rate determines the time required to polish one layer. This determines the maximum throughput of the polisher.

The polishing pad can be selected in combination with a particular slurry mixture to provide a surface that imparts particular polishing characteristics. Thus, for any material to be polished, it is theoretically possible to make the polishing surface have a particular finish and flatness by a combination of pad and slurry. The combination of pad and slurry can provide such finish and flatness within a fixed polishing time. Additional factors, such as the relative speed between the substrate and the pad and the force pressing the substrate against the pad, will affect the polishing rate, finish and flatness.

[0007]

The polishing pad / slurry combination is usually dictated by the required finish and flatness, because improper flatness and finish can result in substrate defects. Given these constraints, the polishing time required to achieve the required finish and flatness determines the maximum throughput of the polishing machine.

Further limiting the throughput of this polishing process is the "glazing" of the polishing pad.
g). Glazing occurs when the pad is heated and compressed in the area where the substrate is pressed. If the crests of the polishing pad are pushed down and the small holes of the polishing pad are filled, the surface of the polishing pad becomes smoother and the polishing property becomes lower. As a result, the time required for polishing the substrate increases. Therefore, it is necessary to maintain a high throughput by periodically returning the surface of the polishing pad to a polishing state or by "adjusting" the polishing pad.

A further consideration in the manufacture of integrated circuits is process and product stability. In order to achieve a low defect rate, each of the successively processed substrates should be polished under similar conditions. Each substrate should be polished by approximately the same amount so that each integrated circuit is substantially the same.

From the above point of view, there is a need for a chemical mechanical polishing apparatus that minimizes the risk of substrate contamination and destruction while optimizing polishing throughput, flatness and finish.

Specifically, there is a need for a carrier head that provides a substantially uniform pressure over the surface of the substrate to be polished. The carrier head should be able to remain substantially parallel to the polishing pad. The temperature of the substrate during polishing should also be controllable.

[0012] Further advantages of the invention are set forth in the following description, and in part will be obvious from the following description, and also some will be learned by practice of the invention.
Some of the advantages of the invention may be realized by the elements and combinations particularly pointed out in the appended claims.

[0013]

One of the embodiments of the present invention is a carrier head for a chemical mechanical polishing apparatus. The carrier head has a housing, a base, a load mechanism, and a gimbal mechanism or a horizontal holding mechanism. The base holds the substrate against the polishing pad. The loading mechanism causes the base to press the substrate against the polishing pad. The gimbal mechanism pivotally connects the housing to the base and allows the base to rotate about a point such that it may be located along the first axis at the interface between the substrate and the polishing pad. To do so.

In another embodiment, the carrier head has a housing, a base, a load mechanism, and a gimbal mechanism or horizontal holding mechanism. The gimbal mechanism connects the housing to the base to rotate the base and to transfer horizontal forces from the base to the housing.

The carrier head may rotate about a second axis substantially perpendicular to the first axis. The loading mechanism may have a flexible seal that allows the base to be connected to the housing to form a chamber therebetween.
The gimbal mechanism may include a gimbal race connected to the carrier, a gimbal rod sliding in a passage in the housing, and a bearing connected to the gimbal rod. A gap may separate the rod from the ceiling of the passage. The gimbal race has a spherical inner surface that engages the spherical outer surface of the bearing. The gimbal mechanism may also include a spring that forces the outer surface of the bearing against the inner surface of the gimbal race.

In another embodiment, a carrier head for a chemical mechanical polishing apparatus includes a housing,
A base, a load mechanism, and a pin (or pins) extending substantially horizontally to connect the base to the housing and rotate the base about a first axis.

The housing may have a vertically elongated aperture through which the pin passes. The slider may fit into this elongated aperture and the pin may extend through a hole in the slider.
The slider is substantially free to move vertically within the aperture, but lateral movement is substantially limited.

In another embodiment, the carrier head includes a housing, a base, a loading mechanism, and a retaining ring assembly. The base has a body and a first annular flange, the gap separating the flange from the body. The retaining ring has a second annular flange that fits within this gap. An annular U-shaped bladder is located in the gap between the flange and the base.

A flexible fluid connector may pass between the housing in the chamber and the base to connect the passage in the housing to the U-shaped bladder.

[0020]

1A-E illustrate a process for depositing a layer on a flat surface of a substrate. As shown in FIG. 1A, the substrate 10 may be treated by coating a flat semiconductor silicon wafer 12 with a metal layer 14 such as aluminum. Then, as shown in FIG.
A photoresist layer 16 may be placed on top of. afterwards,
As will be described in more detail below, the photoresist layer 16 may be exposed to a light image to form a patterned photoresist layer 16 'as shown in FIG. 1C. As shown in FIG. 1D, after forming a photoresist layer 16 ′ having patterning, the exposed surface of the metal layer 14 is etched to form a metal island 14 ′. Finally, as shown in FIG. 1E, the remaining photoresist is removed.

2A-B illustrate the difficulty of successively depositing layers on a substrate. As shown in FIG. 2A, an insulating layer 20 such as silicon dioxide may be formed on the metal island 14 '. The outer surface 22 of the insulating layer 20 has substantially the same shape as the underlying metal island structure and is non-planar to form a series of peaks and valleys.
Depositing and etching multiple layers on the underlying patterning layer will further complicate the outer surface.

As shown in FIG. 2B, the outer surface 2 of the substrate 10
If the 2 is not flat, the photoresist layer 25 placed on it is also not flat. Patterning of the photoresist layer is typically performed by a photolithographic apparatus, which focuses a light image on the photoresist. The optical imaging device typically has a depth of focus of about 0.2 to 0.4 microns for submicron to half micron size features. If the photoresist layer 25 is not very flat, that is, if the maximum difference between the heights of the peaks and valleys on the outer surface 22 is larger than the depth of focus of the optical imaging device, the optical image is accurately focused on the entire surface 22. Would be impossible to do. Even if the optical imager is compatible with the flatness of the underlying patterning layer formed by one layer, the maximum height difference will exceed the depth of focus after deposition of multiple patterning layers. Let's do it.

Redesigning a photolithography apparatus with improved depth of focus is expensive and should not be done. Moreover, as the size of integrated circuit features shrinks, shorter wavelength light is obliged to be used, resulting in a smaller usable depth of focus.

As shown in FIG. 2C, the solution is to flatten the outer surface. In the planarization step, the outer surface, whether metal, semiconductor, or insulator, is ground to form a substantially smooth and flat outer surface 22. This makes it possible to accurately perform focusing of the photolithography apparatus. The planarization step need only be performed if the difference between the peaks and valleys does not exceed the depth of focus, or the planarization step is performed every time a new layer is deposited on the patterning layer. You may go to.

The polishing step can be performed on a metal, a semiconductor, or an insulator. The specific reactive agent, abrasive particles, and catalyst may be changed according to the surface to be polished. The present invention can be applied to any of the layers listed above.

As shown in FIG. 3, the chemical mechanical polishing system 50 according to the present invention has a carry-in device 80 adjacent to the polishing device 60. The carry-in device 80 has an arm 62 capable of rotating and extending, suspended from an overhead track 64. In the figure, the overhead track 64 is partially broken away to show the polishing device more clearly. Arm 62
Is a blade 67 with vacuum port and cassette claw 68
And ends at the wrist assembly 66 with.

The substrate 10 is loaded into the cassette 70 of the polishing system 50 and placed in the holding station 72 or directly in the tab 74. Arm 6
The cassette claw 68 on 4 may be used to grip the cassette 70 and move it from the holding station 72 to the tab 74. The tub 74 may be filled with a liquid bath 75 such as deionized water. The blade 67 secures the individual substrates from the cassette 70 within the tub 74 by a vacuum station, removes the substrates from the cassette 70, and loads the substrates into the polishing apparatus 80. Polishing device 80
When the polishing of the substrate by (1) is completed, the blade 67 returns the substrate to the same cassette 70 or another cassette. Once all the substrates in the cassette 70 have been polished, the claw 68 may remove the cassette 70 from the tab 74 and return the cassette to the holding station.

The polishing device 80 comprises the table top 8
3 has a lower mechanical base 82 mounted on the upper side and a removable upper outer cover (not shown). As best shown in FIG. 4, the table top 83 includes a series of polishing stations 100a, 100b, 100c.
And a transfer station 105. The transfer station 105 includes three polishing stations 1
00a, 100b, 100c form a substantially rectangular arrangement. The transfer station 105 has a plurality of functions, namely, a function of receiving the substrate 10 from the loading device 60, a function of cleaning the substrate, a function of loading the substrate into the carrier head (details will be described later), and a function of loading the substrate. It has a function of receiving from the carrier head, a function of cleaning the substrate again, and a function of returning the substrate to the carry-in device for returning the substrate to the cassette.

Each polishing station 100a, 10
0b or 100c has a rotatable platen 110 on which a polishing pad 120 is placed. Each polishing station 100a, 100b and 100
c may further include a combined pad conditioner device 130. Each pad conditioner device has a rotatable arm 132, which has an independently rotatable conditioner head 134 and a combination cleaning basin 136. The conditioner device controls the condition of the polishing pad to enable effective polishing while the substrate pressed against the polishing pad is rotating.

Adjacent polishing stations 100
a, 100b, 100c and the transfer station 105 between the two intermediate cleaning stations 140a and 140.
b or more may be arranged. The rinsing station rinses the substrate as it moves from polishing station to polishing station.

Rotatable multi-head carousel 15
Zero is given the position above the lower machine base 82. The carousel 150 is supported by a central post 152, on which a carousel motor disposed inside the base 82 rotates about a carousel axis 154. The center post 152 supports the carousel support plate 156 and the cover 158T. The multi-head carousel 150 includes four carrier head systems 160a, 160b, 160.
c and 160d. Three of the carrier head systems receive and hold substrates and platen 1 of polishing stations 100a, 100b, 100c.
The substrate is polished by pressing the substrate against the polishing pad 120 on the substrate 10. One of the carrier head systems receives the substrate from the transfer station 105 and carries it out to the transfer station 105.

In the preferred embodiment, four carrier head systems 160a-160d are connected to the carousel support plate 15.
6 is mounted around the carousel axis 154 at equal angular intervals. The center post 152 is the carousel support plate 1
56, and the carousel support plate 156 is rotated by the carousel motor to rotate the carrier head system 16
0a to 160d and the substrates attached thereto are rotated on the orbit around the carousel axis.

Carrier head systems 160a-160
d has a polishing head or carrier head 180. Each of the carrier heads 180 rotates about its own axis and independently reciprocates horizontally within a radial slot 182 formed in the support plate 156. Carrier drive shaft 184 connects carrier head rotary motor 186 to carrier head 180 (shown with quarter cover 158 removed). Each head has one carrier motor shaft and one motor, respectively.

The substrate attached to the bottom of the carrier head 180 may be moved up and down by the polishing heads 160a to 160d. An advantage of the carousel system as a whole is that the polishing head system takes a short vertical stroke to receive the substrate and place it for polishing and cleaning. An input control signal (eg, pneumatic, hydraulic or electrical signal) is applied to extend or retract the carrier head 180 of the polishing head system to accommodate the required vertical stroke. Specifically, the input control signal causes the lower carrier member having the wafer receiving recess to
It is moved vertically relative to the stationary upper carrier member.

During the actual polishing, three of the carrier heads, namely the polishing head system 160a.
.About.160c each occupy a position above each polishing station 100a-100c. Each of the rotating platens 110 supports a polishing pad whose top surface is wet with polishing slurry. The carrier head 180 lowers the substrate into contact with the polishing pad 120, and the polishing slurry acts as a medium for chemical and mechanical polishing of the substrate or wafer.

The conditioner device 130 adjusts the condition of the polishing pad 120 each time the substrate is polished. The arm 132 sweeps the conditioner head 134 over the entire surface of the polishing pad 120 by reciprocating between the center and the outer edge of the polishing pad 120. The conditioner 134 has a polishing surface such as a nickel-coated diamond surface. The polishing surface of the conditioner head 134 is pressed against the rotating polishing pad 120, and the pad is ground and adjusted.

In use, the polishing head 180
Is, for example, the fourth 160d of the carrier head system.
Are first placed above the wafer transfer station 105. While the carousel 150 is rotating, the carrier head systems 160a, 160b, 160c, 16
0d is the polishing station 100a, 100b,
100c and transfer station 105. Carousel 150 allows each of the polishing stations to be arranged in series, first on transfer station 105, then on one or more of polishing stations 100a-100c, and back on transfer station 05.

5A to 5F show a carousel and insertion of a substrate such as a wafer (W) and a carrier head system 16.
4 illustrates carousel motion for a series of motions from 0a to 160d. As shown in FIG. 5A, the first wafer (W # 1)
From the loading device to the transfer station 105,
There, the wafer is cleaned and transported to the carrier head 180, eg, the first carrier head system 160a. Then, the carousel 150 is supported to support the center post 15.
2 is rotated counterclockwise so that the first carrier head system 160a with the wafer (W # 1) is located at the first polishing station 100a, as shown in FIG. The # 1 first polishing step is performed. First polishing station 100a
The second wafer (W # 2) is transferred from the carry-in device to the transfer station 105 while polishing the wafer (W # 1) at the same time, and from there, occupies a position above the transfer station 105 at this point. The second carrier head system 160b. Then, the carousel 150 is rotated again by 90 ° counterclockwise, and as shown in FIG. 5C,
The first wafer (W # 1) is arranged above the second polishing station 100b and the second wafer (W # 2) is arranged above the first polishing station 100a. The third carrier head system 100c is located above the transfer station 105 from which it receives the third wafer (W # 3) from the loading system 60. In a preferred embodiment, during the stage shown in FIG. 5 (g), the wafer (W # 1) at the second polishing station 100b has finer grain polishing than when it was at the first polishing station 100a. The material is polished. In the next stage, as illustrated in Figure 5D,
The carousel 150 is again rotated counterclockwise by 90 ° to move the wafer (W # 1) to the third polishing station 100.
wafer (W # 2) on the second polishing station 1
00b, the fourth carrier head system 160d moves the wafer (W # 3) from the carry-in device 60 to the fourth wafer (W # 4) while occupying the respective positions on the first polishing station 100a. ) To accept. It is preferable that the polishing step in the third polishing station is finer than the polishing step in the second polishing station 100b. After the end of this stage, the carousel 150 is rotated again. However, here, the carousel 150 is rotated clockwise by 270 ° instead of being rotated counterclockwise by 90 °. By avoiding continuous rotation in one direction, the carousel 150 can use simple flexible fluid and electrical connections rather than complex rotary couplings. Due to this rotation,
As shown in E, the wafer (W # 1) is on the transfer station 105, the wafer (W # 2) is on the third polishing station 100c, and the wafer (W # 3) is on the second polishing station 100b. On top of the wafer (W #
4) is on the first polishing station 100a,
It will be arranged respectively. Wafer (W # 2)
Wafer (W # 1) while (W # 4) is being polished
Are washed at the transfer station 105 and returned from the carrier head system 160a to the carry-in device 60. Finally, as shown in FIG. 5F, the fifth wafer (W # 5) is loaded into the first carrier head system 160a.
After this stage, the process is repeated.

A carrier head system, such as system 160a, lowers the substrate into engagement with a polishing station, such as polishing station 100a, as shown in FIG. As mentioned above, each of the polishing stations has a rigid platen 110 supporting a polishing pad 120. Substrate 1
If 0 is an 8 inch (200 mm) diameter disk, the platen 110 and polishing pad 120 are
It will be about 20 inches in diameter. The platen 110 is preferably rotatable aluminum or stainless steel that is connected to a platen drive motor (not shown) by a stainless steel drive shaft. In most polishing processes, the drive motor drives the platen 110 (120) at 30-200 rpm (revolutio
The rotation speed is lower than this, but a lower rotation speed or a higher rotation speed may be adopted.

The polishing pad 120 has a rough surface 12.
Made of a rigid composite material having 2. The polishing pad 120 includes a hard upper layer 124 having a thickness of 50 mil,
It may have a soft underlayer 126 with a thickness of 50 mils. The upper layer 124 is preferably made of a material in which polyurethane is mixed with a filler. The lower layer 126 is preferably made of a material composed of compressed felt fibers that have been strained with urethane. The upper layer is IC-400 (trade name), the lower layer is
A common two-layer polishing pad composed of SUBA-4 (trade name) is available from Rodel, Inc. of Newark, Del., USA. In one embodiment, polishing pad 120 is adhered by pressure sensitive adhesive layer 128.

Each of the carrier head systems has a rotatable carrier head. The carrier head has an upper surface 22 on the outer surface 1 of the polishing pad 120.
The substrate 10 is held by pushing the substrate 22 by pushing down on the surface. In the main polishing step, which is usually done in step 100a, the carrier head 180 is about 4-10 psi.
Is applied to the substrate 10. At subsequent stations, the carrier head 180 may exert more or less force. For example, in the final polishing step, which typically takes place at station 100c, carrier head 180 is subjected to a force of about 3 psi. Carrier drive motor 18
6 (see FIG. 4), the carrier head 180 has about 30
Rotate at ~ 200 rpm. In the preferred embodiment, platen 110 and carrier head 180 rotate at substantially the same speed.

A slurry 190 having a reactant, abrasive particles (eg, silicon dioxide for polishing oxides), and a chemical reaction catalyst (eg, potassium hydroxide for polishing oxides).
However, the slurry supply pipe 195 causes the polishing pad 120 to
Supplied to the surface. Sufficient slurry is supplied to cover the entire polishing pad 120 and make it wet.

Chemical mechanical polishing is a rather complex process and differs from simple wet sanding. In the polishing process, the reactive agent in the slurry 190 reacts with the conductive, semi-conductive or insulating surface 22 of the upper layer 20 and with the abrasive particles,
Form reactive sites. Interaction of the polishing pad, abrasive particles, and reactive agent with the substrate occurs during polishing.

As shown in FIG. 7, the carousel support plate 1 is shown with the cover 158 of the carousel 150 removed.
56 is four carrier head systems 160a-16
0d is supported. The carousel support plate has four slots 1 that extend approximately radially and are oriented at 90 ° intervals.
82. The slot 182 may be closed end (as shown) or open end. The upper portion of the support plate 156 supports a carrier head support slide 200 having four slots. Each of the slides 200 is centered along one of the slots 182 and is free to move along a radial path relative to the support plate 156. Two linear bearing assemblies 201 surround each of the slots 182 and support each of the slides 200.

As shown in both FIGS. 7 and 8, each of the linear bearing assemblies 201 includes a support plate 156.
And a two hands (only one of which is shown in FIG. 8) fixed to the slide 200 holding the rail. Bearing 206
Thus, each of the hands is separated from the rail 202 and gives a free and smooth motion between them.
Thus, the linear bearing assembly allows slide 200 to move freely along slot 182.

The bearing stop 208 is the rail 20.
Tightly secured to the outer end of one of the two, preventing the slide from accidentally falling from this end of the rail. One of each arm of slide 200 has a recirculation ball threaded receiving cavity or nut, not shown here, which is secured near the end of the slide. This threaded cavity or nut is a support plate 1
It has a worm gear lead screw 210 driven by a slide oscillator motor 212 mounted on 56. When the motor 212 turns the lead screw 210, the slide 200 moves in the radial direction. The four motors 212 are independently operable to independently move the four slides 200 along the slots 182 of the carousel support plate 156.

Each slide 200 is associated with an optical position sensor 224. Wings 22 extending horizontally
Angle iron 220 having 2 slide 20
On each side of the 0 worm. Support plate 15
An optical position sensor 224 is fixed at 6. The height of sensor 224 is such that wing 222 passes through the two jaws of sensor 224, and sensor 22
Linear position along slot 182 of four slides 2
Wings 222 are provided to pass from one side of sensor 224 to the other side as 00 moves from the innermost position to the outermost position. The position of the slide is
It is monitored by an input to the motor 212 or an encoder attached thereto, but this monitoring method is indirect, and errors are accumulated. The optical position sensor 224 adjusts the electronic monitor and is particularly useful when there is a machine controlled power outage or similar loss.

The carrier head assemblies each include a carrier head 180 and a carrier drive shaft 184.
, A carrier motor 186, and a non-rotating shaft housing 226 surrounding the carrier motor 186, and are fixed to each of the four slides 200. The drive shaft 226 is a pair of lower ring bearings 2
42 and the pair of upper ring bearings 244,
Holds the drive shaft 184. Each of the carrier head assemblies can be assembled separately from the polishing device 80 and can be slid into the slot 182 between the arms of the slide 200 of the carousel support plate 156 where it is untightened. It can be tightened to grip the slide.

The rotary coupling 230 on top of the drive motor 186 provides four fluid or electrical lines 23.
Two drive shafts 184 with four channels 234 (FIG. 8 shows only two channels due to cross-section)
Connect to. Base flange 238 of drive shaft 184
The four channels 234 are connected to the receiving channels of the carrier head 180 by the inclined passages 236 formed in the. As will be described in more detail below, the channel 234 is used to pneumatically power the carrier head 180 to control the temperature of the carrier head and to vacuum chuck the substrate to the bottom of the carrier head.

As shown diagrammatically in FIG. 9, the carrier head 180 consists of three main assemblies.
That is, the base assembly 250 and the housing assembly 252.
And the retaining ring assembly 254. Details of each of these assemblies are described below.

The base assembly 250 loads the substrate 10, ie, presses the substrate 10 against the polishing pad 120. The housing assembly 252 connects to and is rotated by the drive shaft 184. Torque pin 256 connects housing assembly 252 to base assembly 2
Connect to 50 to transfer torque to the base assembly for rotation. The base assembly 250 is a gimbal mechanism 25.
8 which allows the base assembly 250 and the retaining ring assembly 254 to pivot two-dimensionally around a point 260 at the interface between the substrate 10 and the polishing pad 120. . Gimbal mechanism 258
Is in an "unloaded state", that is, no downward force is applied from the housing assembly 252 to the base assembly 250 via the gimbal mechanism. However, the gimbal mechanism 258 transfers any side load to the housing assembly 252, such as shear due to friction between the substrate and the polishing pad, without affecting the non-uniformity of pressure on the substrate. . Further, the gimbal mechanism 258 keeps the base assembly rotating about the same axis as the drive shaft.

A seal 262 is included in the housing assembly 252.
To the retaining ring assembly 254 to connect the pressure chamber 2
64 are formed. A fluid, preferably air, pumps in and out of the pressure chamber 264 through one of the channels 234 of the drive shaft 184 to control the load applied to the base assembly. Gimbal mechanism 258
Is slidable vertically with respect to the housing assembly 250 to allow side load transmission to continue and the base assembly rotating about the same axis as the drive shaft. It should be held regardless of the distance between the housing and the housing assembly.

The retaining ring assembly 254 prevents the substrate 10 from being pushed out of the carrier head 180 beneath it due to the shearing forces created by the movement of the polishing pad 120.
To prevent. Retaining ring assembly 254 projects downwardly from the outer edge of carrier head 180 to contact polishing pad 120.

This configuration has a number of advantages.
First, the pressure chamber 264 provides a load substantially evenly across the substrate rather than in the substrate center under the drive shaft. Second, the bottom surface 266 of the base assembly that holds the substrate 10 on the polishing pad 120 can be pivoted relative to the drive shaft 184 so that it remains parallel to the polishing pad and thus end to end of the substrate. It is that the load can be evenly applied. Third
In addition, the housing assembly 252 provides torque to the base assembly 2
Transfer to a portion of the 50 very close to the bottom surface 266 to reduce tension on the carrier head and improve load non-uniformity. Unlike other polishing systems that apply pressure unevenly across the substrate, the carrier head 180 distributes pressure evenly across the wafer 10, which is above the non-uniform areas of the polishing pad 120. Even when they move.

As shown in FIGS. 8 and 9, the carrier head 180 is connected to the drive shaft 184 via the housing assembly 252. The housing assembly 252 includes a hub 420, as described in further detail below. Several dowel pins 438 are located in the mating dowel holes in the hub 420 and flange 238 to circumferentially align the annular channel 236 of the drive shaft 184 with the receiving channel 436 of the carrier head (see FIG. 13). .. As the drive shaft 184 rotates, the dowel pin 438 transfers torque to the housing assembly 252, causing it to rotate about the same axis as the drive shaft.
The hub has a threaded neck 430 to which a peripheral nut 240 is attached. The peripheral nut has a lip that fits over the top of the flange 238 to secure the drive shaft 184 to the carrier head 180.

As shown in FIG. 10, the base assembly 2
50 has a disk-shaped carrier head, which has a substantially flat bottom surface 266 that can also contact the substrate 10. The carrier base 270 may be aluminum or steel. Top surface 27 of carrier base 270
4 is a circular basin 276 surrounded by a ledge 278.
have. Basin 276 has a flat annular surface 280 surrounded by rim 282. The moat 284 separates the squat conical turret 286 from the annular surface 280 at the center of the carrier base 270. The conical turret 286 has a flat top 288 with sloped sides 290. The center of the conical turret 286 is a shallow conical depression 292. The conical recess 292 may be formed in a disc-shaped insert 293 that fits into the cylindrical recess of the top 288.

A plurality of conduits 294 are provided in carrier base 27
0 evenly arranged around the central axis of the carrier base 2
It extends through the body portion 298 of 70 from the bottom surface 266 to the annular surface 280. An annular flange 300 projects downwardly from the outer edge 302 of the ledge 278,
Also, a U-shaped gap 304 is formed by the flange 300 and the body portion 298.

The gimbal mechanism 258 includes the conical turret 28.
6 above and allows the base assembly 250 to rotate in two dimensions relative to the housing assembly 250. The gimbal mechanism 258 includes a gimbal body 310,
And a gimbal race 360. In one embodiment, gimbal mechanism 258 is made of steel.
The gimbal body 310 includes a cylindrical gimbal rod 311.
Has a top surface 312, and the top surface 312 has a bearing base 31.
It projects from 4. The bearing base 314 has a spherical outer surface 316. As shown in FIG.
The inner surface 318 of the bearing base 314 has a conical recess 320 that fits into the conical turret 286 when the base is fully assembled.

As shown in FIG. 11, the cylindrical passage 322 projects upward from the center of the depression 320 and reaches the inside of the gimbal rod 311. Cylindrical passage 322
Are broken down into three parts of decreasing diameter.
The cylindrical passage 322 has a guide pin 324. The top of the guide pin 324 is a knob 326, which fits within the uppermost narrowest portion 328 of the passage 322. The bottom of the guide pin 324 has a disk 330 with a spherical protrusion 332 that engages the conical recess 292 of the conical turret 286. The spring 334 can be formed by stacking beveled washers, and the passage 3
22 steps or shoulders 336 and disc 33
Fitting with the zero top, "preloads" the gimbal, ie, provides a constant upward pressure on the bearing base 314.

Returning to FIG. 10, an annular cooling plate 340 is placed on the annular surface 280 in the basin 276.
The gimbal rod 311 is attached to the central opening 34 of the cooling plate 340.
It penetrates through 2. The cooling plate 340 has a thin inner ring 344 and a thick outer ring 346.
A thick outer ring 346 abuts the inner surface of the rim 282,
Moreover, it is approximately the same height as the rim 282. Cooling plate 34
The lower side 348 of 0 rests against the annular surface 280. The lower side 348 of the cooling plate 340 has a series of grooves. As will be more clearly understood in FIG. 12, the grooves form a series of concentric circular channels 352 extending across the lower edge of the cooling plate 340. Adjacent circular channels 352 are connected by a cross channel 353. The cooling plate 340 has an annular surface 28.
When pressed firmly to zero, these channels provide passageways 35 for the flow of a coolant fluid such as water.
Form 0. 1 continuous cross channel 353
The 80 ° spacings ensure that the coolant fluid flows through the entire outer circular channel before entering the inner circular channel. Two connecting conduits 644 and 646 lead from the lower side 348 of the cooling plate 340, through the inner ring 344 and the outer ring 346, to the upper surface 354, and the inlet 356 and outlet 3 of the channel 352.
57 is connected to the two fittings 652 and 654 (see FIGS. 19A and 19B). The passage 350 can have many shapes, such as a vortex shape or a simple circular shape.

The gimbal race 360 includes the gimbal body 3
It fits around 10, extends through the openings 342 in the cooling plate 340 and is placed on the carrier base 270. The gimbal race 360 has a flat outer piece 362 that rests on a wedge-shaped inner piece 364 that fits within the annular surface 280 and the moat 284. The spherical inner surface 366 of the wedge component 364 engages the spherical outer surface of the bearing base 314. Flat parts 3
The outer edge of 62 is the inner edge 3 of the inner ring 344.
It has a lip 368 that fits over 70.

The lower side 372 of the outer part 362 has a circular groove 374. When the gimbal race 360 is positioned opposite the annular surface 280, the circular groove 374 aligns with the conduit 294 to form a connecting passage. A conduit (not shown) extends through the flat piece 362 to connect the groove passage 374 to a fitting (not shown). This joint may connect to one of the channels of the carrier drive shaft 184. Channel 234,
A vacuum is applied through groove 374 and conduit 294,
The substrate 10 may be chucked on the bottom surface 266 of the carrier head 180. Alternatively, the pressure of the air is applied to the channel 23
4, groove passage 374 and conduit 294 may be provided to release substrate 10 from bottom surface 266. The two O-rings 376 and 378 may be made of rubber and may fit into the circular grooves 380 and 382 of the annular surface 280 to seal the groove passage 374.

The bolt 386 fits into the bolt hole 387 of the gimbal race 360, and the carrier base 27
0 corresponding threaded bolt holes 388. In one specific example, there are eight bolts (only four are shown because it is a perspective view in cross-section). Bolts 386 hold the gimbal race 360 in place. Wedge parts 36
4 holds the gimbal body 310 in place and the spring 334
Between carrier base 270 and gimbal body 310. The lip 368 of the flat piece 362 holds the coolant plate 340 in place on the basin 276. An O-ring (not shown) fits within the circular embodiment (not shown) of the inner edge 370 to seal the inner edge of the coolant plate.

The gimbal body 310 is the gimbal race 36.
Once fixed by the zero, the spring 334 exerts a force on the bearing base 314 to force it into the gimbal race 360.
Press against the inner surface of. Additionally, the spring 334 will press the spherical protrusion 332 of the guide pin 324 into the conical recess 292. This pressure will push the center of the carrier base outward, perhaps hundreds of microinches, so that the bottom surface 266 of the carrier base is
Is no longer flat. Therefore, the base assembly 2
Before the 50 is assembled, the bottom surface 266 is lapped or polished to restore a very flat surface.

The base assembly 250 may optionally include a wet carrier film disposed between the carrier base 270 and the substrate 10. Carrier film 3
The top surface 392 of 90 may be attached to the bottom surface 266 of the carrier base 270 by, for example, an adhesive or the like. The hole 394 of the carrier film 390 is formed in the carrier base 2
Align 70 conduits 294. 1 for each conduit 294
There is one hole 394. Bottom surface 3 of carrier film 390
96 will contact the wafer. The carrier film 390 has a thickness of 20 mil (1 mil = about 25.4 μ).
It may be a urethane film of m). The carrier film 390 is slightly compressible and conforms to the surface of the substrate. The carrier film 390 also functions as a cushion to prevent substrate slip during polishing.

The base assembly 250 also includes a linear roller bearing 400 such as a roller cage assembly. The linear roller bearing 400 is a hollow cylindrical tube. A number of small bearings 402 are set in the gap between the inner surface 404 and the outer surface 406 of this cylindrical tube. Inner surface 404 of linear roller bearing 400
Fit snugly around the gimbal rod 311. The small bearing 402 has surfaces 404 and 40.
Rotate around the horizontal axis of rotation that contacts 6. The roller bearing 400 moves the gimbal rod 311 up and down smoothly.

As shown in FIG. 13, the housing assembly 252 has an inverted bowl-shaped carrier housing 410. The housing assembly 252 is made of aluminum. The bottom surface 412 of the carrier housing 410 is
It has a conical hub 414 and a cylindrical cavity 416 intermediate the conical hub. The cylindrical cavity 416 is open at the bottom but closed at the top by the ceiling 418. Upper surface 4 of carrier housing 410
19 is a cylindrical hub 42 protruding above the annular region 422.
It has 0. Circular ridge 424 defines annular region 422.
And a lower ledge 426 extends around the circular ridge 424. The flange 428 forms the side of the bowl-shaped carrier housing 410, which projects downwardly from the edge of the ledge 426. The lower rim of the flange 300 of the carrier base 270 and the flange 428 of the carrier housing 410 have approximately the same height. However, as will be described below, the base assembly 250 is vertically movable relative to the housing assembly 252 so that the flanges 300 and 428 are movable relative to each other.

The cylindrical hub 420 has a threaded neck 43.
0 and two vertical dowel pin holes 432 on the circular surface 434
(Only one of these is shown). Several slanted conduits extend through the hub 420 from the lower surface 412 to the circular surface 434.
Is growing. There is one inclined conduit 436 for each of the channels of drive shaft 184. O-ring 437 inserted into top surface 434 of hub 420
Surrounds each conduit 436 (see FIG. 11). Drive the carrier head 180 by inserting two dowel pins 438 into the dowel pin holes 432 and lifting the carrier head so that the dowel pins fit within the pair of dowel pin holes (not shown) in the drive shaft flange 238. It may be attached to the shaft 184. This aligns the inclined passage 236 with the conduit 436. Then thread the threaded peripheral nut 240 into the threaded neck 374.
Screw the carrier head 180 onto the drive shaft 1
It can be securely attached to 84.

Housing assembly 252 also includes a plain bushing 440, which may be made of stainless steel. Bushing 440
Fits into the cylindrical cavity 416 such that its outer surface 442 abuts the conical hub 414. The linear roller bearing 400 engages the inner surface 444 of the bushing 440 when the housing assembly 252 is lowered onto the base assembly 250. Cylindrical cavity 4
16 is deep enough so that the top surface 312 of the gimbal rod 311 does not contact the ceiling 418 of the cavity 416. This prevents pressure from being applied to the substrate 10 via the gimbal body 310, that is, there is a contact surface for transmitting a downward force from the housing assembly 252 to the base assembly 250 via the gimbal mechanism 258. Will not do.

Referring to FIG. 13, the seal 262 is the rim 2
Outer clamp ring 45 having a radius greater than 82
It has 0. The outer clamp ring 450 has a square cross-section and may rest on the ledge 278 in an unfixed manner. The outer clamp ring may have twelve evenly spaced threaded recesses 452 (only four of which are shown).

The seal 262 has a thickness of 60 mils.
Rollable diaphragm 4 made of silicone
60. Rollable diaphragm 460
Is a ring-shaped, flat outer 462 and inner edge 4
64 and. Rollable diaphragm 460
Of the carrier base 270 rests on the rim 282 of the carrier base 270, and its inner edge 464 fits within a ring 466 that runs along the inner edge of the rim 282.
The outer portion of rollable diaphragm 460 rests on outer clamp ring 450. Rollable diaphragm 460 may have twelve slots 468, which may be aligned with twelve recesses 452 in outer clamp ring 450.

An inner clamp ring 470 is used to seal the rolling diaphragm 460 to the base assembly 250. Inner clamp ring 470 primarily rests on top surface 354 of cooling plate 340. The inner clamp ring 470 has an outer lip 472 that projects above the rim 282 of the carrier base 270. The inner clamp ring 470 is a thick outer ring 346 of the cooling plate 340.
12 holes 4 aligned with the mating thread cutting recess 478
It may have 76 (only two are shown in FIG. 13). Thread screw 474 passes through each hole 476 and engages threaded recess 478. The screws are tightened to hold the bulge 464 of diaphragm 460 securely within recess 466. Additionally, an O-ring (not shown) may be placed in the circular groove 480 located between the recess 478 and the rim 282. Diaphragm 4
The bulge of 60 and the O-ring of groove 480 seal the outer edge of cold plate 340.

The housing assembly 252 is the base assembly 2
It is possible for the seal 262 to be complete when it is lowered above 50. The carrier housings 410 are formed on the ledge 426 and are evenly spaced apart.
It may have one bolt hole 484 (5 in FIG. 13).
(Only shown). These bolt holes are used for the diaphragm 460.
Aligned with slot 468 of the. Twelve screws (only five shown) 486 fit into holes 484 in carrier housing 410
Through the slot 468 of the diaphragm 460 and the threaded recess 45 of the outer clamp ring 450.
2 is engaged. When the screw 486 is tightened, the outer clamp recess 450 secures the outside of the diaphragm 460 to the bottom surface 412 of the carrier housing 410. In this way, the space between housing assembly 252 and base assembly 250 is sealed to form pressure chamber 264.

As shown in FIG. 14, the retaining ring assembly 254 includes a base assembly 250 and a housing assembly 2.
It is attached to 52. FIG. 14 shows the base assembly and housing assembly inverted, and the assembled retaining ring assembly lowered to that position. As will be described below, the retaining ring assembly 254 can be actuated to press against the polishing pad 120 to hold the substrate 10 in place under the carrier head 180. The retaining ring assembly 254 can be actuated to move vertically up and down relative to the base assembly 250, but the retaining ring assembly rotates with the base assembly.

Retaining ring assembly 254 includes an annular piston frame 490 having a generally J-shaped cross section.
Retaining ring assembly 254 may be made of aluminum. The piston frame 490 has a radially extending cross piece 492, an inner annular flange 494 that projects downward from an inner edge of the cross piece 492, and an outer annular flange 496 that projects downward from an outer edge of the cross piece 492. . The inner flange 494 is
It fits inside the U-shaped gap 304 of the base assembly 250. The outer flange 496 is longer than the inner flange and the outer flange 428 of the housing assembly 252.
Fit around.

As shown in FIG. 15, a lip 498 projects laterally outward from the inner edge of the cross piece 492. The carrier base 270 has a mating lip 500 that projects outwardly from the bottom of the body 298. When the carrier head 180 is assembled, the lip 498
Is almost in contact with the lip 500.

As shown in FIGS. 11 and 14, outer flange 496 extends above cross piece 492 to form ridge 506. The ridge 506 projects vertically beyond the outer surface 504.

Retaining ring assembly 254 also includes retaining ring 510. The retaining ring 510 is attached to the outer surface 504 of the cross piece 492. The retaining ring 510 is a generally flat ring, which may be made of plastic and has an outer ring portion 512 that is thinner than the inner ring portion 514. The outer ring 512 is adjacent to the ridge 506 and is approximately the same height.
Eight evenly spaced threading recesses (not shown) may be formed in the outer surface 504 of the cross piece 492, and each of these recesses may be in the outer ring 512 from top to bottom. It may have a bolt hole (not shown) penetrating therethrough. Bolts (not shown) are inserted through each bolt hole into the mating recesses on the upper surface 504 to attach the retaining ring 510 to the piston frame 490.

As shown in FIG. 15, the inner ring 51
4 almost contacts the lip 500 of the carrier base 270. The surface 516 of the inner ring 514 can project slightly below the bottom surface 266 of the base assembly 250 and can contact the polishing pad 120 (see FIG. 15). The shearing force generated by the relative speed between the substrate 10 and the polishing pad 120 causes the carrier head 18 to move.
The substrate tends to be pushed out from under 0. In the lowered position shown in FIG. 13, the retaining ring 510 blocks the substrate 10 and prevents it from sliding under the carrier base 270.

Returning to FIG. 14, the retaining ring assembly 254.
Is activated by the annular rubber bladder 520. The bladder 520 can simply be a small tube, but the bladder preferably has a U-shaped cross section. To provide a force-pressure relationship that is insensitive to the position of the retaining ring assembly relative to the base assembly,
Design the rolled shape of the bladder 520. The bladder 520 is placed in the U-shaped gap of the carrier head 270 so that the lower “U” side 522 is located at the bottom of the gap. The piston frame 490 is positioned with the retaining ring 510 attached to it such that the inner flange 494 fits snugly within the “U” inner surface 524 of the bladder 520 (see also FIG. 15). The bladder 520 has a carrier base 27.
Valve 5 inserted into the first channel 528 of 0
26. The first channel 528 is the main body 2
Through 98 and connect to the second channel 530 of the coolant plate 340. The second channel 530 is connected to the joint 532. The connection between the first channel 528 and the second channel 530 can be sealed by an O-ring (not shown). Joint 53
2 is connected by a hose or bellows (see FIG. 19A) to one of the inclined conduits 436 of the conical hub 414. Bladder 52
Inflate 0 to force retaining ring 510 against polishing pad 120. The bladder 520 and the pressure chamber 264 can be independently pressured and the loads applied to the retaining ring and the substrate are independent of each other so that they can be independently controlled.

The piston frame 490 is attached to the bladder 520.
The piston frame 490 after being positioned to engage the
Attach the stop ring 540 to the rim of the outer flange 496 of the. The bolt 542 passes through the bolt hole 544 of the stop ring 540, and the piston frame 49
Engage 0 threaded recesses 546 to connect the ring to the frame. The lower side 548 of the stop ring 50 captures the ledge 426 and prevents the retaining ring assembly 254 from falling out when the carrier head 180 rises and clears the polishing pad 120. Gap 58
0 retainer ring assembly 254 to housing assembly 25
Separated from two. Stop ring 540 and ledge 42
A barrier 582 between 6 and 6 fits over the gap between flange 496 and flange 428 to prevent the slurry from entering carrier head 180.

As mentioned above, the torque pins transmit torque from the housing assembly 252 to the base assembly 250,
On the other hand, the base assembly 250 moves vertically with respect to the housing assembly 252. As shown in FIGS. 14, 15 and 16, the body 298 of the carrier base 270 has two opposing lateral pin receiving recesses 550. The recess 550 is formed on the bottom surface 26 of the carrier base 270.
Placed right beside 6 and torque is carrier head 1
The signal is transmitted to the surface close to the boundary between the substrate 80 and the substrate 80. Each of the recesses 550 has an exterior 552 that is wider than the threaded interior 554. A torque pin 256 fits into the recess 550 through the opening in each flange. The torque pin 256 has a beveled tip 556 to facilitate insertion of the pin into the recess 550, and the torque pin has a narrow threaded end 558 that engages the threaded interior 554.

The outer end of the torque pin 256 is attached to the housing assembly by a slightly elastic slider 560 which is mounted on the flange 4.
Fits into 28 square slots 562. FIG.
The slider 560 has a rectangular wedge 564 and two wings 566 laterally projecting from the rectangular wedge 564, as shown more clearly in FIG. The slider hole 568 in the radial direction is
0 is formed. Slider 560 is wing 5
66 can be pushed into the rectangular slot 562 so as to capture the flange 428. Slider 560
The wedge-shaped portion 564 has the same width as the rectangular slot 562, but its length is such that it is vertically movable in the rectangular slot 562 and not laterally.
It is shorter than the slot 552. Torque pin 25
6 is inserted into the slider hole 568, and its head 570
Are caught until they are caught on the outer surface of the slider 564 or the annular lip (not shown) inside the slider hole 568. An O-ring (not shown) may be fitted inside the slider hole 568 to elastically retain the torque pin 256. Flange 428 rotates when drive shaft 184 rotates carrier housing 420. The carrier base 270 is attached to the flange 428 by the torque pin 256 and the slider 560. The slider and O-ring have sufficient elasticity,
The torque pin 256 meets manufacturing tolerances so that both torque pins can withstand the rotational load. Furthermore,
The slider 560 can move up and down in the rectangular slot 562 so that the base assembly 250 can move vertically with respect to the housing assembly 252 without affecting rotation.

As already mentioned, the torque pin 256 fits into the opening in the other flange. The outer flange 496 of the piston frame 490 has an access aperture 572 for this purpose. Access aperture 572 does not transmit torque. This provides an opening for inserting the torque pin 256 into the slider 560. Carrier base 27
The circular aperture 574 of the flange 300 of 0 aligns with the recess 550 of the body 298,
The elongated aperture 576 of the 0 inner flange 494
Align the circular aperture 574 and other openings through which the torque pin will extend. Torque pin 256
Fits within the elongated aperture 576 and is vertically movable but not horizontally within this aperture. The elongated aperture 576 transmits torque to the retaining ring assembly 254, while the housing assembly 2
52 and the base assembly 250 can be independently vertically moved.

As shown in FIG. 11, stop ring 540 includes torque pin 256 and elongated aperture 57.
6 to prevent diaphragm 460 from over stretching. When the carrier base 270 is pushed down, the torque pin 256 will move to the elongated aperture 576.
Pressed down to the bottom of the. This causes the piston frame 490 to be pushed downward and the stop ring 540 to be captured by the ledge 426.

17 and 18, the carrier head 18 is shown.
Another specific example of 0 is shown. In this specific example, the configuration of the carrier head 180 shown in FIG. 11 is modified by various methods. Housing assembly 2 for diaphragm 460
The connector to 52 has been changed. The contact between stop ring 540 and ledge 426 has been modified. In addition, the gimbal mechanism 258 and the carrier base 270
The same applies to the contact portion between the and and via the spring 334. FIG.
Among the components of the embodiments shown in FIGS. 7 and 18, those similar to the embodiment shown in FIG. 11 but modified are indicated by adding a dash (') to the reference numeral.

As shown in FIG. 17, the diaphragm 4
60 'has a thick outer edge 600 and the upper surface of outer clamp ring 450' has a recess 602. The hole 484 'in the ledge 426' and the recess 452 'in the outer clamp ring 450' are located radially outward from the recess 602. Outer clamp ring 450 '
Is provided by a screw 486 that engages the recess through the hole
It is mounted on the carrier housing 410 '. The outer edge 600 fits tightly in the recess 602 and holds the diaphragm 46 against the carrier housing 410 '.
The 0'is sealed to form the pressure chamber 264. Outer clamp ring 450 'and carrier housing 41
The metal-to-metal contact with 0'prevents excessive compression of diaphragm 460 ', thus improving its life and performance.

In the specific example of FIG. 17, the retaining ring assembly 2
Instead of the stop ring (see FIG. 11) attached to 54, the carrier base 270 ′ and housing assembly 2
Direct contact with 52 prevents excessive stretching of diaphragm 460 '. In the configuration of FIG. 17, the outer flange 496 ′ and the inner flange 49 of the piston frame 490 ′ are
4'are almost the same height, and the outer flange has a ledge 4
It has not reached 26 '. The flange 428 'projects downwardly from the edge of the ledge 426' of the carrier housing 410 ', and the upper ring 610 and the lower ring 6'.
12 are provided. The lower ring 612 has a larger radius than the upper ring 610 such that the upper ring 610 is positioned above the outer flange 496 ′ of the retaining ring assembly 254, and the lower ring 612 is located inside the outer flange 496 ′. Fit concentrically.

The carrier base 270 'has a ledge 27.
It has a lip 614 protruding from the 8'edge.
When the carrier base 270 'is depressed by pumping air into the pressure chamber 264, the lip 614
Catches against the face 616 of the flange 428 'to stop downward movement of the carrier base, and the diaphragm 46
Prevents excessive stretching of 0 '. The flange 428 'is not an integral part of the carrier housing 410' but may be bolted or screwed (not shown) into the carrier housing 41 '.
It is attached to 0 '. The direct contact between lip 614 and surface 616 reduces stress on torque pin 256 '.

The rubber seal 618 is attached to the outer flange 49.
Fit above the gap between 6'and the upper ring 610 to seal the carrier head 180 'from the slurry. The seal 618 has a shape similar to a "headband" and has O-rings (not shown) on its top and bottom edges. The seal 618 is flexible such that the retaining ring assembly 254 allows the housing assembly 252 to
When it moves downward with respect to, it can be stretched.

In addition, in the embodiment shown in FIGS. 17 and 18, in order to improve the flatness of the bottom surface 266, the contact between the spring 334 and the carrier base 270 'is eliminated. As shown in FIG. 18, the gimbal mechanism 258 ′ has an X-shaped member 620, which has a central cylindrical portion 624.
It has four vertical rods 622 protruding from it. The upper surface 626 of the central cylindrical portion 624 has a conical recess 292 '.
have. The central cylindrical portion 624 fits within the lower conical recess 320 of the bearing base 314 '.

The bearing base 314 ′ of the gimbal body 310 ′ has four vertical slots 628 for receiving the rod 622. The guide pin 324 and the spring 334 fit in the cylindrical passage 322 (see FIG. 17). The X-shaped member 620 is the gimbal mechanism 2
58 ', so that the spherical protrusion 332 on the bottom surface of the guide pin engages the conical recess 292' of the central cylindrical portion 624, and the rod 622 is inserted into the slot 628 of the bearing base. It will grow. The wedge shaped member 364 'of the gimbal race 360' has several notches 630. When the gimbal race 360 'is positioned on the gimbal mechanism, the end 631 of each rod 622 is mounted over the respective notch 630 of the gimbal race 360'. For example, bolts or screws (not shown) may be used as wedge-shaped members 36.
It may pass through a hole (not shown) on the outer surface of 4'to reach the threaded recess at the end of each rod. The entire assembly may then be placed in a flat bottomed recess 632 in the center of the carrier base 270 '.

Once the gimbal mechanism 258 'is assembled, the spring 334 forces the gimbal body 310' upwards and separates it from the X-shaped member.
The 4'spherical outer surface 316 'is pressed against the spherical inner surface 366' of the gimbal race 360 '. The gimbal body 310 'can still pivot in two dimensions relative to the gimbal race 360' because the rod 6
This is because 22 can slide in the slot. However, the X-shaped member 620 causes the gimbal race 36 to
Since it is fixed at 0 ′, the downward force from the spring 334 is not transmitted to the carrier base 270. Since there is no outward force at the center of the carrier base, the bottom surface 266 of the carrier base 270 ′ has a gimbal mechanism 2.
When 58 'is attached to the carrier base,
It remains flat.

In another specific example of the carrier head 180 shown in FIG. 21, the vertical pin 700 is used and the base assembly 2 is used.
Torque is transmitted directly from 50 to the retaining ring assembly 254. Among the parts in FIG. 21, those similar to the above-mentioned specific example but modified are shown by adding a double dash (″) to the reference numeral.

As shown in FIG. 21, the retaining ring 25
4 has a retaining ring 510 attached to the piston frame 290 ″. Piston frame 490 ''
The inner flange 494 and the outer flange 496 ″ of the same have substantially the same height. The inner surface 702 of the outer flange 496 '' has three evenly spaced vertical grooves 704 in the shape of a semicircle (since the figure is a cross-sectional view,
Only two are shown). The outer surface 706 of the flange 300 ″ of the carrier base 270 ″ is also 3 equally spaced.
It has one semicircular vertical groove 708 (only two are shown because the figure is a cross-section). The inner flange 494 of the retaining ring assembly 254 is
Fit in the gap 304 of the bladder 520 and contact the bladder 520. The outer surface 706 of the flange 300 ″ engages the inner surface 702 of the outer flange 496 ″ so that the groove 704 engages the groove 708 to form three vertical cylindrical passages.

Three cylindrical pins 700 fit within the cylindrical passages to transfer torque from the base assembly 250 to the retaining ring assembly 254. With pin 700
The base assembly 250 is allowed to slide vertically with respect to the retaining ring assembly 254. Base assembly 2
As 50 rotates about axis 296, pin 700 provides a lateral connector for the base assembly to rotate the retaining ring assembly. Further, the base assembly 25
0 swivels with respect to the housing assembly 252,
The pin 700 keeps the retaining ring aligned with the base assembly. A stop ring (not shown) may fit over the flange 496 ″ to constrain the pin 700 vertically. The stop ring may have a protrusion that directly engages the housing assembly 252 to limit vertical downward movement of the retaining ring assembly.

Outer flange 4 of piston ring 490 ''
The inner surface 702 of the 96 ″ has two opposing rectangular vertical recesses 7
10 (only one shown), and the flange 428 'of the housing 410''may have two downwardly projecting tabs 712 (only one shown). Each of the tabs 712 has a rectangular slot 562. The tab 712 fits within a vertical recess 719 between the outer surface 706 of the base assembly 250 and the inner surface 702 of the retaining ring assembly 254. As mentioned above,
The slider may fit within a square slot 562 and a torque pin may extend through a hole in the slider to connect the housing assembly 252 to the base assembly 250.

As shown in FIGS. 19A and 19B, the polishing apparatus of the present invention has several fluid lines for letting a fluid such as water into and out of the carrier head 180. As described in more detail below, these fluid lines are used to apply pressure to chamber 264 to actuate retaining ring assembly 252, control the temperature of carrier head 180, and bring the substrate to the bottom of the carrier head. A vacuum chuck may be used. In the configuration illustrated in FIG. 19A, the polishing device has five fluid lines, and in the configuration illustrated in FIG. 19B, the polishing device has four fluid lines.

Some of these fluid lines have a connector for fluid flow between the base assembly 250 and the housing assembly 252. Since the base assembly 250 and housing assembly 252 move vertically relative to each other, a flexible fluid connector is used for the pressure chamber 264. These flexible fluid connectors connect the angled conduits of housing assembly 252 to various conduits of base assembly 250. The joint between each flexible fluid connector and each conduit is sealed by a fitting to prevent connector fluid from leaking into the pressure chamber.
Each flexible fluid connector may be plastic tubing or metal bellows.

As described above, some of the fluid lines are used for controlling the temperature of the carrier head. CM
Since P partially includes a chemical process, the polishing rate changes depending on the temperature of the substrate. In general, polishing proceeds faster at higher temperatures. Heat is generated due to the friction between the substrate 10 and the polishing pad 120. This heat is stored in the carrier head and platen.
For example, after continuing polishing for 30 minutes, the temperature at the interface between the substrate 10 and the polishing pad 120 will rise from room temperature of 20 ° C to 40-50 ° C. As the temperature of the polishing machine rises with the number of substrates that have been polished, each of the series of substrates placed in the polishing machine will be exposed to different temperatures, i.e. different polishing rates. Becomes To keep the polishing constant, each substrate should be exposed to substantially the same temperature.

Previous polishing systems have attempted to control the temperature of the substrate by controlling the temperature of the platen. However, the polishing pad is not effective as a heat conductor, that is, controlling the platen temperature does not effectively control the substrate temperature. The polishing system of the present invention solves such a problem by controlling the temperature of the carrier head 180.

As shown in FIG. 19A, two fluid lines allow a coolant such as water or glycol to circulate in the carrier head 180. Specifically, the coolant enters the inflow line 232a from the heat exchanger 640 and enters the rotary coupling 2
30, flow channel 232a of drive shaft 184, conduit 436a of housing assembly 252, and flexible fluid connector 642 of pressure chamber 264. From the flexible fluid connector 642, the fluid flows through the connecting conduit 644 and the base assembly 2
50 into the inlet 356 of the passage 350. The coolant circulates in the passage 350 to absorb the heat generated by the friction between the substrate and the polishing pad. The coolant is
Once it has begun to circulate in this passage, it exits through outlet 357 and exits outlet conduit 646 to flexible fluid connector 648. From there, the coolant flows through conduit 436b of housing assembly 252, drive shaft 18
4 channel 234b, rotary coupling 23
0, flows in the discharge line 232b, and then returns to the heat exchanger 640. The heat exchanger can be operated to maintain the temperature of the coolant at a set temperature, for example between 5 ° C and 100 ° C. The heat exchanger may have a pump 650 such as a positive displacement pump or a centrifugal pump to pump the coolant in the carrier head.
Additionally, a thermocouple (not shown) may be embedded within the base assembly 250 to sense the temperature of the carrier head 180.

In one of the embodiments illustrated in FIG. 20,
Flexible fluid connectors 642 and 648 connect the fitting 652 of the housing assembly 252 to the base assembly 25.
It is a plastic pipe to be connected to the zero joint 654. Fittings 652 and 654 seal the joint between the plastic tubing and the conduit to prevent fluid leakage into chamber 264. Plastic tubing is half wrapped around the conical hub 414 and gimbal rod 311
It may be wound four times, or one or more times.
When the volume of pressure chamber 264 increases and the base assembly moves downward relative to the housing assembly, the tubing stretches minimally. In another embodiment not illustrated here, the flexible fluid connector may be a metal bellows. The metal bellows is expandable and contractable to fit the height of the pressure chamber 264. Preferably, the metal stretches one joint with another that is directly overhead.

With this structure, heat is transferred to the coolant and carried to the heat exchanger 640. Controlling the carrier head temperature will control the substrate temperature as both the carrier base and the carrier film conduct heat efficiently.

Another line of polishing equipment is used to press the substrate against the polishing pad, as shown in FIG. 19A and as described above. Pump 670 forces a fluid, preferably air, into and out of pressure chamber 264.
Pump 670 includes fluid line 232c, drive shaft 1
It is connected to the pressure chamber 264 via the channel 234c of 84 and the conduit 436c of the housing assembly 252. The pump 670 may be a positive displacement pump or a centrifugal pump. As fluid is pumped into the pressure chamber 264, the pressure rises and pushes the base assembly 250 downward against the housing assembly 252.

Also, as described above, another line of polishing equipment is used to operate the retaining ring assembly. Retaining ring assembly 254 is used by bladder 5 by pump 675.
It works by inflating 20. Pump 675
Line 232d, channel 234d of drive shaft 184, conduit 436d of housing assembly 252, flexible fluid connector 677 through pressure chamber 264, second channel 53 of carrier base 270.
0, carrier-based first channel, and valve 5
By 26, it is connected to the bladder 520. Fitting 678
And 532 seal the flexible fluid connector 677 to the conduit 436d and the second channel 530. Flexible fluid connector 677 may be a metal bellows (not shown) or flexible plastic tubing. The pump 680 may forcibly input a fluid such as air into the bladder 520 to expand and contract the bladder. Since the polisher uses separate fluid lines for the pressure chamber and the bladder, the polisher provides an independently controllable load on the retaining ring.

As mentioned above, the fluid lines of the polishing apparatus may be used to vacuum chuck the substrate to the carrier head. However, the vacuum chuck implementation will depend on how many lines are provided by the polishing apparatus 80. As shown in FIG. 19A, the rotary coupling 230 may have 5 or more junctions so that the polishing device can have 5 fluid lines. In the embodiment of FIG. 19A, drive shaft 184 has five channels 234a-234e.
The housing assembly 252 may include five conduits 436a-436e.

Pump 680 may apply a vacuum to conduit 294 to chuck substrate 10 to bottom surface 266. Also,
Pump 680 blows air through conduit 294.
Thus, the substrate 10 is pushed and released from the bottom surface 266. Pump 280 includes line 232e, channel 234e of drive shaft 184, conduit 436 of housing assembly 252.
e, via the flexible fluid connector 682 of pressure chamber 264, passage 684 and circular passage 374,
Connected to conduit 294. Preferably, the flexible fluid connector 682 is a metal bellows. 2
Two fittings 686 and 688 seal the flexible fluid connector to conduit 436e and passage 684. 6
If present, this line may be used for electrical connection to the thermocouple.

As shown in FIG. 19B, the rotary coupling 230 may have only four junctions, just as a polishing device has only four fluid lines. In the embodiment of FIG. 19B, drive shaft 18
4 has four channels 234a-234d, and the housing assembly 252 has four corresponding conduits 43
6a to 436d. Carrier head 180
By using the passages associated with the cooling system,
A vacuum or forced fluid is provided in conduit 294.

As shown in FIG. 19B, several valves are provided to allow controlled chucking and release of the substrate. The inflow valve 690 connects the heat exchanger 640 to the inflow line 232a and the exhaust valve 692 connects the heat exchanger 640 to the exhaust line 232b. The first check valve 694 and the second check valve 696 connect the passage 374 to the passage 350 of the cooling system. The first check valve 694 remains closed when there is fluid in the passage 350 and opens when there is a vacuum in the passage 350. Second check valve 696
Is spring loaded and remains closed unless the pressure in passage 350 exceeds a predetermined value.

When the carrier head presses the substrate against the polishing pad, the inlet valve 690 and the outlet valve 6
92 is opened and the heat exchanger 640 passes the coolant through the passage 3
Pump to 50. Here, as the fluid flows through the passageway 350, check valves 694 and 69
6 remains closed, blocking conduit 294.

However, the polishing apparatus may chuck the substrate to the bottom surface 266 as the substrate moves between polishing stations. In order to chuck the substrate, the inlet valve 690 is closed and the outlet valve is closed,
Pump 650 continues to pump fluid out of passage 350. Pump 650 reduces the pressure in passage 350 until first check valve 694 opens to connect conduit 294 to passage 350. This causes a vacuum to be applied to conduit 294 which causes substrate 10 to
Chuck to 6.

When the carrier head is located at the transfer station, the polishing machine places the substrate on the bottom surface 266.
May be released from. To release the substrate, the inlet valve 690 is opened, the outlet valve 692 is closed, and the pump 650 continues to pump fluid into the passageway 350. Pump 650 raises the pressure in passage 350 until the pressure in passage 350 is greater than the opposing force from the spring and second check valve 696 opens to connect conduit 294 to passage 350. Coolant conduit 29
4 may be forced outward to release the substrate 10 from the carrier head.

In summary, the carrier head of the present invention uses the pressure chamber and the floating gimbal. This floating gimbal allows the carrier base to pivot with respect to the drive shaft, but at this time no downward force acts on the substrate via the gimbal. Instead, a rolling diaphragm seals the carrier base to the carrier housing,
Form a chamber. By applying pressure to the chamber, it is possible to apply an even load across the substrate. The retaining ring has an inflatable bladder
The load is given independently. Torque is transferred from the carrier housing to the carrier base by two horizontal pins located near the board. The pins can slide vertically within the housing, but not laterally. However, both torque pins are able to withstand the load of rotation because there is sufficient resilience to allow the torque pins to meet manufacturing tolerances. The bottom channel of the cold plate is connected to the heat exchanger by a flexible fluid connector running through the chamber to allow temperature control of the carrier head.

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

[Brief description of the drawings]

1A-1E are schematic cross-sectional views of a substrate illustrating the deposition and etching of layers on the substrate.

2A to 2C are schematic cross-sectional views of a substrate illustrating a process of polishing a non-flat outer surface of the substrate.

FIG. 3 is a schematic perspective view of a chemical mechanical polishing device.

4 is a schematic perspective exploded view of the chemical mechanical polishing apparatus of FIG.

5A to 5F are schematic top views of a polishing apparatus showing states of a wafer when loading and polishing are continuously performed.

FIG. 6 is a schematic side view of a substrate on a polishing pad.

FIG. 7 is a schematic top view of the carousel with the upper housing removed.

8 is a schematic cross-sectional view of the carrier head of FIG. 7, taken along line 8-8.

FIG. 9 is a schematic diagram of main components of a carrier head according to the present invention.

FIG. 10 is a schematic exploded view of a base assembly of a carrier head according to the present invention, with a partial cross-sectional view.

FIG. 11 is a schematic sectional view of a carrier head according to the present invention.

FIG. 12 is a schematic bottom view of the cooling plate of the base assembly of the carrier head.

FIG. 13 is a schematic exploded view and partial cross-sectional view of a housing assembly of a carrier head according to the present invention.

FIG. 14 is a schematic exploded view and partial cross-sectional view of a retaining ring assembly for a carrier head according to the present invention.

15 is an enlarged view of a torque pin assembly of the carrier head shown in FIG.

FIG. 16 is a schematic exploded view of a torque pin assembly for transmitting torque from the housing assembly of the present invention to the base assembly of the carrier head.

FIG. 17 is a schematic sectional view of a part of a carrier head according to the present invention.

FIG. 18 is a schematic exploded view of the gimbal mechanism of the carrier head according to the present invention, which is a partial sectional view.

FIG. 19A is a schematic diagram of a fluid line of a carrier head of the present invention connected to a drive shaft having five or more channels. FIG. 19B is a schematic diagram of a fluid line of the carrier head of the present invention connected to a drive shaft having four channels.

FIG. 20 is a schematic exploded perspective view of piping in a pressure chamber for supplying a coolant to a carrier head according to the present invention.

FIG. 21 is a schematic exploded view of a carrier head according to the present invention, partially in cross-section.

[Explanation of symbols]

10 ... substrate, 12 ... silicon wafer, 14 ... metal layer,
14 ': metal island, 16: photoresist layer, 16' ...
Patterned photoresist layer, 20 ... insulating layer,
22 ... Outer surface, 25 ... Photoresist layer, 60 ... Loading device, 62 ... Arm, 64 ... Overhead track, 6
6 ... Wrist assembly, 67 ... Blade, 68 ... Cassette claw, 70 ... Cassette, 72 ... Holding station, 74
... Tab, 80 ... Polishing device, 82 ... Machine base, 83
... table top, 100 ... polishing station,
105 ... Transfer Station, 110 ... Platen, 12
0 ... polishing pad, 121 ... ring region, 122 ...
Pad surface, 123 ... Center, 124 ... Pad upper layer, 12
5 ... Edge, 126 ... Lower layer, 128 ... Adhesive layer, 130 ...
Pad conditioner device, 132 ... Arm, 134
… Conditioner head, 136… Wash basin, 1
40 ... Washing station, 150 ... Carousel, 152
... central post, 154 ... carousel shaft, 156 ... carousel support plate, 158 ... cover, 160 ... carrier head system, 180 ... polishing head or carrier head, 182 ... slot, 184 ... carrier drive shaft, 186 ... carrier head rotation motor, 190 ... Slurry, 195 ... Slurry supply pipe, 200 ... Carrier head support slide, 201 ... Linear bearing assembly, 20
2 ... Rail, 204 ... Hand, 206 ... Bearing, 2
08 ... Bearing stop, 210 ... Lead screw, 212 ...
Motor, 220 ... Angle iron, 222 ... Wing, 224 ... Optical position sensor, 226 ... Shaft housing, 230 ... Rotary coupling, 232 ... Line, 234 ... Channel, 236 ... Passage, 238 ... Base flange, 250 ... Base assembly , 252 ... Housing assembly, 254 ... Retaining ring assembly, 256 ... Torque assembly, 258 ... Gimbal mechanism, 260 ... Point, 26
2 ... Seal, 264 ... Pressure chamber, 266 ... Bottom surface, 2
70 ... Carrier base, 274 ... Top surface, 276 ... Basin, 278 ... Ledge, 282 ... Rim, 284 ... Moat, 28
6 ... Turret, 288 ... Top, 290 ... Side, 292 ...
Recess, 293 ... Insert, 294 ... Conduit, 296 ... Central axis, 298 ... Main body portion, 300 ... Flange, 302 ...
Outer edge, 304 ... U-shaped gap, 310 ... Gimbal body, 311 ... Gimbal rod, 312 ... Top surface, 31
4 ... Bearing base, 316 ... Spherical outer surface, 318 ... Inner surface, 320 ... Indentation, 322 ... Cylindrical passageway, 324 ... Guide pin, 326 ... Knob, 328 ... Top narrowest part, 33
0 ... Disk, 332 ... Spherical protrusion, 334 ... Spring, 3
36 ... Shoulder, 340 ... Cooling plate, 342 ... Center opening, 344 ... Inner ring, 346 ... Outer ring, 348
... Lower side, 350 ... Passage, 352 ... Concentric circular channels,
353 ... Cross channel, 356 ... Inlet, 357 ...
Discharge port, 360 ... Gimbal lace, 362 ... Outer part,
364 ... Inner part, 366 ... Spherical inner surface, 368 ... Lip, 370 ... Inner edge, 372 ... Lower side, 374 ... Circular groove, 376, 378 ... O-ring, 380, 382
… Circular groove, 386… Bolt, 387… Bolt hole,
388 ... Threaded bolt hole, 390 ... Carrier film, 392 ... Top surface, 394 ... Hole, 396 ... Bottom surface, 400
… Roller bearings, 402… Bearings, 404…
Inner surface of tube, 406 ... Outer surface of tube, 410 ... Carrier housing, 412 ... Bottom surface, 414 ... Conical hub, 416 ... Cylindrical cavity, 418 ... Ceiling part, 420 ... Cylindrical hub, 422
... annular region, 424 ... circular ridge, 426 ... lower ledge, 428 ... flange, 430 ... neck, 432 ... dwell pin hole, 434 ... circular surface, 436 ... inclined conduit, 437
... O-ring, 438 ... Dwell pin, 440 ... Bushing, 442 ... Outer surface, 444 ... Inner surface, 450 ... Clamp ring, 452 ... Threaded recess, 460 ... Diaphragm, 462 ... Outer, 464 ... Inner edge, 466 ... Recess, 468 ... Slot 470 ... Clamp ring, 47
2 ... Outer lip, 474 ... Thread screw, 476 ... Hole, 4
78 ... Recessed thread cutting recess, 480 ... Circular groove, 4
84 ... Bolt hole, 486 ... Screw, 490 ... Annular piston frame, 492 ... Cross part, 494 ... Inner annular flange, 496 ... Outer annular flange, 498 ... Lip, 5
00 ... mating lip, 506 ... ridge, 510 ... retaining ring, 512 ... outer ring portion, 514 ... inner ring portion, 516 ... inner ring surface, 520 ... bladder, 5
22 ... U-shaped lower side, 526 ... Valve, 528 ... First channel, 530 ... Second channel, 532 ... Joint,
540 ... Stop ring, 542 ... Bolt, 544 ... Bolt hole, 546 ... Threaded recess, 548 ... Stop ring lower side, 550 ... Pin receiving recess, 552 ... Recess outside, 554 ... Recess inside, 556 ... Tip, 558 ...
Threaded end portion, 560 ... slider, 562 ... slot, 564 ... rectangular wedge-shaped portion, 566 ... wing, 5
68 ... slider hole, 570 ... torque pin head, 5
72 ... access aperture, 574 ... circular aperture, 576 ... elongated aperture, 580 ... gap, 5
82 ... Barrier, 600 ... Outer edge, 602 ... Recess,
610 ... Upper ring, 612 ... Lower ring, 614 ... Lip, 616 ... Surface, 618 ... Seal, 620 ... X-shaped member, 622 ... Rod, 624 ... Central cylindrical portion, 626 ... Top surface, 628 ... Vertical slot, 630 ... Notch, 631 ...
Rod end, 640 ... Heat exchanger, 642 ... Fluid connector, 644, 646 ... Connection conduit, 648 ... Fluid connector, 650 ... Pump, 652, 654 ... Fitting, 670 ...
Pump, 675 ... Pump, 677 ... Fluid connector, 6
80 ... Pump, 682 ... Fluid connector, 684 ... Passage, 690 ... Inflow valve, 692 ... Discharge valve, 694
... first check valve, 696 ... second check valve, 700 ... vertical pin, 702 ... inner surface of outer flange,
704 ... Vertical groove, 706 ... Outer surface of flange of carrier base, 708 ... Vertical groove, 710 ... Rectangular vertical recess, 712 ... Tab.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Stefan Jay. Blumenkranz USA, California, Redwood City, Hillcrest Drive 954

Claims (21)

[Claims] 1. A carrier head for a chemical mechanical polishing apparatus, comprising: a housing connected to a drive shaft, the housing rotating about a first axis by the drive shaft; A base connected to the housing and rotating about the first axis; a load mechanism for actuating the base to press the substrate against the polishing pad; and a housing pivotable about the base. And a gimbal mechanism that allows the base to rotate around a point of a boundary between the substrate and the polishing pad. 2. The carrier head of claim 1, wherein the point is located along the first axis. 3. A carrier head for a chemical mechanical polishing apparatus, comprising: a housing connected to a drive shaft, the housing rotating about a first axis by the drive shaft; A base connected to the housing and rotating about the first axis; a load mechanism for actuating the base to press the substrate against the polishing pad; and a housing pivotable about the base. And a gimbal mechanism that allows the base to rotate with respect to the housing and allows horizontal force to be transmitted from the base to the housing. 4. The carrier head according to claim 3, wherein the gimbal mechanism is slidably connected to the housing. 5. The gimbal mechanism includes a gimbal rod that slides through the passage of the housing along the first axis, the gimbal rod being separated from the ceiling of the passage by a gap. The listed carrier head. 6. The base relative to the housing,
4. The carrier head of claim 3, which rotates about a second axis that is substantially perpendicular to the first axis. 7. The base relative to the housing,
The carrier head of claim 6, wherein the carrier head rotates about a point of a boundary between the substrate and the polishing pad. 8. The carrier head of claim 7, wherein the point is located along the first axis. 9. The carrier head of claim 3, wherein the loading mechanism includes a flexible seal that connects the base to the housing and forms a chamber therebetween. 10. The gimbal mechanism includes: a gimbal race having a spherical inner surface and connected to the base; and a gimbal rod that slides through a passage of the housing along the first axis, wherein A bearing connected to the gimbal rod, wherein the gimbal rod is separated from the passage;
10. The carrier head of claim 9, wherein the bearing has a spherical outer surface that can be engaged with the inner surface of the gimbal race. 11. The carrier head of claim 10, further comprising a spring for biasing the outer surface of the bearing against the inner surface of the gimbal race. 12. The method further comprising a rigid member connected to the gimbal race, the member being disposed between the bearing and the base, the spring providing a force that pushes the bearing away from the member. 11. The carrier head according to item 11. 13. A carrier head for a chemical mechanical polishing apparatus, comprising: a housing connected to a drive shaft, the housing rotating about a first axis by the drive shaft; A base connected to the housing and rotating about the first axis; a load mechanism for actuating the base to press the substrate against the polishing pad; A rod disposed in a passage along an axis of the rod, the rod being fixed to the base and transmitting force from the base to the housing; and a gap separating the rod from a ceiling portion of the passage. Carrier head with. 14. The carrier head of claim 13, further comprising a linear bearing that surrounds the rod in the passage and transfers a horizontal force from the base to the housing. 15. A carrier head for a chemical mechanical polishing apparatus, the housing being connected to a drive shaft, the housing rotating about a first axis by the drive shaft, and the base holding a substrate against a polishing pad. A load mechanism for exerting a surface of the base against the polishing pad; and connecting the base to the housing so that the base rotates about the first axis. Head with a horizontally horizontal pin. 16. The carrier head of claim 15, wherein the housing has a vertically elongated aperture and the pin extends from the base through the elongated aperture. 17. A slider disposed within the elongated aperture, the pin extending through a hole in the slider, the slider being substantially free to move vertically within the aperture. 17. The carrier head of claim 16, wherein the carrier head is capable of substantially limited lateral movement. 18. The carrier head of claim 15, further comprising a second substantially horizontal pin connecting the base to the housing. 19. A carrier head for a chemical mechanical polishing apparatus, the housing being connected to a drive shaft and rotating about a first axis by the drive shaft; and a base for holding a substrate against a polishing pad. Wherein the base comprises a body and a first annular flange projecting downwardly from an outer edge of the body, a gap separating the first flange from the body; the polishing pad; A loading mechanism for actuating the base against the base plate, a retaining ring assembly having a second annular flange disposed in the gap, the flange in the gap and the A carrier head having an annular U-shaped bladder disposed between the base and the base. 20. The loading mechanism connects the base to the housing to form a chamber therebetween.
20. The carrier head of claim 19, having a flexible seal. 21. The carrier head of claim 20, further comprising a flexible fluid connector that passes through the chamber and connects a passage in the housing to the U-shaped bladder.