JP3693448B2 - Substrate gripping apparatus and polishing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus for flattening a polishing object such as a semiconductor wafer.
[0002]
[Prior art]
In recent years, as semiconductor devices are highly integrated, circuit wiring is becoming finer and the distance between wirings is becoming narrower. In particular, in the case of optical lithography of 0.5 μm or less, the depth of focus becomes shallow, so that the flatness of the imaging surface of the stepper is required. Therefore, it is necessary to flatten the surface of the semiconductor wafer, and polishing is performed by a polishing apparatus as one means of this flattening method.
[0003]
As a conventional technique of this type of polishing apparatus, for example, a polishing apparatus described in JP-A-6-198561 is known. This polishing apparatus includes a turntable with an abrasive cloth on the upper surface, a top ring body provided opposite to the turntable, a pressing device for pressing the top ring body, and a rotational drive for driving the top ring body. It is the structure provided with the drive device.
[0004]
As shown in FIGS. 4 and 5, the top ring main body 100 is connected to the pressing device and the driving device via a driving shaft 102 (spline shaft). A flange portion 104 is formed on the lower end portion of the drive shaft 102 so as to protrude laterally, and a plurality of drive pins 106 are provided on the side to protrude in the radial direction. On the other hand, a plurality of driven pins 108 project upward from the upper surface of the top ring body 100, and the driving pins 106 and the driven pins 108 are engaged with each other by the rotation of the driving shaft 102. Power is transmitted to the top ring main body 100.
[0005]
Further, spherical recesses 110 and 112 are formed in the lower end of the drive shaft 102 and the upper surface of the top ring main body 100, respectively, and a wear-resistant sphere 114 is slidably disposed on the recesses 110 and 112 to constitute a spherical bearing 116. ing. As a result, even if the turntable is tilted with respect to the drive shaft 102, the top ring main body 100 follows and tilts, and the polishing object is brought into close contact with the turntable surface.
[0006]
With such a configuration, the polishing object W is rotated by rotating the turntable and the top ring body 100 while pressing the polishing object W toward the turntable with a predetermined force via the top ring body 100. The surface is polished to be flat and mirror-finished.
[0007]
A shaft hole 118 is provided at the center of the drive shaft 102, the upper part of the shaft hole 118 communicates with an external device such as a fluid supply source or a vacuum source, and the top ring main body 100 is connected to the lower part of the shaft hole 118. One end of a tube 120 communicating with a gap with the substrate W, which is an object to be polished, is joined, and fluid can be transferred between an external device and the polishing device via the tube 120, or a top ring body The substrate W is vacuum-adsorbed on 100, or the polishing target object W is pressed against the turntable by fluid pressure during polishing.
[0008]
[Problems to be solved by the invention]
In the above-described conventional polishing apparatus, the drive shaft 102 is made of metal, and if there is a pin hole in the inner surface of the shaft hole 118, the surface of the shaft hole 118 may be coated for rust prevention. Insufficient coating may rust the surface. Then, even if pure water is supplied to the gap between the top ring main body 100 and the polishing object W through the shaft hole 118, the rust is mixed in the pure water and contaminates the wafer, and the product characteristics are slowed down. There was a risk of letting it go.
[0009]
An object of this invention is to provide the board | substrate holding | grip apparatus which can supply the clean fluid which does not contaminate a polishing target object between a top ring and a polishing target object in view of the said subject.
[0010]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problems. The invention according to claim 1 is directed to a top ring body that grips a substrate facing the turntable, and the top ring body via a spherical bearing. A drive shaft that is tiltably supported, and a shaft hole is formed in a central portion of the drive shaft. One end communicates with an external device such as a fluid source in the shaft hole, and the other end A flow pipe communicating between the top ring main body and the polishing object is inserted , the top ring main body grips the substrate on the lower surface, the grip plate having a recess formed in the center of the upper surface, and the above-mentioned in the center of the lower surface And the spherical bearing is disposed so that at least a part thereof is positioned inside the concave portion of the gripping plate, and the depth of the concave portion of the gripping plate. Larger than the height of the convex portion of the covering plate, the concave portion A gap is formed between the convex portion, the flow tube is a substrate holding apparatus, characterized by being communicated with the gap between the recess and the protrusion.
[0011]
According to the present invention, a shaft hole is provided in the central portion of the drive shaft, and a flow pipe made of an appropriate material different from the drive shaft is provided in the shaft hole, and fluid such as pure water is exchanged with the top ring body by the flow pipe. Since it is supplied to the gap with the polishing object, rust is prevented from entering the fluid, contamination of the substrate due to rust is prevented, and polishing accuracy and quality are improved.
[0012]
According to a second aspect of the present invention, the grip plate is formed with a flow hole penetrating vertically, and the flow pipe is formed in the communication hole of the grip plate through a gap between the concave portion and the convex portion. a substrate holding apparatus according to claim 1, wherein the benzalkonium been communicated.
The invention according to claim 3 is characterized in that the spherical bearing is provided between a recess formed in the lower surface of the drive shaft and a recess formed in the upper surface of the cover plate. Item 3. The substrate gripping apparatus according to Item 1 or 2.
The invention according to claim 4 further includes a transmission mechanism that is provided between an end of the drive shaft and the top ring body and transmits a rotational driving force from the drive shaft to the top ring body. A substrate gripping device according to any one of claims 1 to 3.
The invention of claim 5 includes a turntable having a polishing surface, Ru polishing apparatus der characterized by having a substrate holding apparatus according to any one of claims 1 to 4.
[0013]
【Example】
Hereinafter, an embodiment of a substrate gripping apparatus according to the present invention will be described with reference to FIGS. The substrate gripping device includes a disc-shaped top ring body 10 as a whole, a drive shaft 12 that supports the top ring body 10 and transmits a rotational driving force and a pressing force thereto, and the drive shaft 12 and the top. It is comprised from the universal joint part 14 which connects the ring main body 10 accept | permitting mutual tilting.
[0014]
In this example, the top ring body 10 has a gap S between the upper surface of the gripping plate 16 and a substantially disc-shaped gripping plate 16 that grips a semiconductor wafer (substrate) that is an object to be polished by suction or the like. The cover plate 18 is formed in a substantially disk shape and is stacked and fixed so as to be formed, and the holding plate 16 and a hollow disk-shaped presser plate 20 that covers and holds the cover plate 18 from above. A guide ring 22 is attached to the outer periphery of the lower part of the grip plate 16 so as to surround the outer periphery of the substrate.
[0015]
A concave portion 24 is formed in the center on the upper surface of the grip plate 16 (the rear surface when the substrate mounting side is the front surface), and a step surface 26 is formed in the peripheral portion thereof. On the other hand, on the lower surface of the cover plate 18, a convex portion 28 that fits into the concave portion 24 of the gripping plate 16 is formed at the center, and a thin flange portion 30 that is bolted to the stepped surface 26 of the gripping plate 16 at its peripheral portion. Is provided. A recess 32 is formed at the center of the upper surface of the cover plate 18, an annular shoulder portion 34 is formed so as to surround the periphery, and a stepped surface 36 for attaching the presser plate 20 is formed on the outer side.
[0016]
The depth of the concave portion 24 of the gripping plate 16 is larger than the height of the convex portion 28 of the covering plate 18, whereby a gap S having a predetermined thickness is formed between the concave portion 24 and the convex portion 28. . A large number of flow holes 38 are formed in the grip plate 16 so as to be inserted vertically. The flow holes 38 communicate with the connection holes 40 of the presser plate 20 through the gap S between the cover plate 18 and the grip plate 16. . The circulation hole 38 communicates with the back surface of the substrate held on the lower surface of the gripping plate 16. As will be described later, the gap S holds the pressure fluid. When the vacuum source is connected, the suction force acts on the back surface of the substrate. On the other hand, when the pressure fluid source is connected, the pressing force is applied. It is like that.
[0017]
The drive shaft 12 is supported rotatably and vertically movable by a top ring head 42 fixedly provided in the polishing apparatus, and a drive source (motor with a speed reducer, not shown) provided on the top ring head 42. And a pulley belt mechanism 44, and is structured to be moved up and down by expansion and contraction of a rod 48a of a top ring cylinder 48 provided between the top ring head 42 and the drive shaft holder 46. . That is, the main body of the top ring cylinder 48 is fixed to the shoulder portion of the drive shaft holder 46, and the tip of the rod 48 a is fixed to the top surface of the top ring head 42.
[0018]
The drive shaft 12 is formed in a hollow cylindrical shape, and the shaft hole 50 at the center thereof is communicated with an external fluid supply device 54 via a rotary joint 52 attached to the upper end. A tube (flow pipe) 56 formed of a material such as Teflon or polypropylene having corrosion resistance is inserted into the shaft hole 50, and the upper end thereof communicates with the rotary joint 52 and the lower end is a branching portion. The two branch pipes 56 a and 56 b are connected to the connection hole 40 of the presser plate 20 through 57. Since the pressure fluid is transferred between the rotary joint 52 and the upper end of the shaft hole 50, it is not necessary to provide a lateral hole communicating with the side of the shaft hole 50 in the drive shaft 12, the structure is simple, and the manufacturing is performed. Cost is also reduced.
[0019]
The external fluid supply device 54 includes, for example, a vacuum source 58, a pressurized air source 60, a pure water supply source 62, and the like. These supply sources 58, 60, 62 include a selection control valve 64, a rotary joint, and the like. 52, the flow pipe 56 and the branch pipes 56a and 56b are selectively communicated with the flow hole 38 of the holding plate 16. A polishing abrasive nozzle (not shown) is installed above the turntable so that the polishing abrasive can be supplied to the polishing cloth on the turntable.
[0020]
A drive plate 68 having a flange portion 66 projecting outward is fixed to the lower end portion of the drive shaft 12. A universal joint 14 is provided between the drive plate 68 and the cover plate 18 of the top ring body 12 so as to tiltably support the top ring body 12 and transmit a pressing force. The universal joint 14 includes a spherical bearing mechanism 70 and a drive shaft. And a rotation transmission mechanism 72 that transmits the 12 rotations to the top ring body 10.
[0021]
In the spherical bearing mechanism 70, a spherical recess 80 for slidably receiving a bearing ball 78 made of a high hardness material such as ceramics is formed at the center of a convex portion 76 formed at the center of the lower surface of the drive plate 68. A spherical recess 82 that also accommodates the bearing ball 78 is formed at the center of the bottom surface of the recess 32 at the center of the upper surface of the cover plate 18. The lower end of the bearing 78 is located in the recess 24 of the gripping plate 16, that is, located below the level of the step surface 26. Thus, the curved bearing can be brought closer to the turntable by providing a concave portion on the gripping plate and a convex portion on the covering plate to make the top ring thin, and positioning at least a part of the curved bearing in the concave portion. it can. The distance L from the center of the bearing ball 78 to the lower surface of the gripping plate 16 is preferably set to 26 mm or less. As a result, the polishing apparatus is of a low fulcrum type and can apply a stable load to the substrate.
[0022]
A plurality of (six in this example) pins 84 and 86 are erected on the shoulder 34 projecting around the recess 32 of the cover plate 18 at equal angular intervals when viewed from above. Holes 88 and 90 formed at corresponding positions of the flange portion 66 of the drive plate 68 are inserted. These pins are alternately provided with a suspension pin 84 that suspends the top ring body 10 and a driven pin 86 that transmits the rotation of the drive shaft 12 to the top ring body 10. The suspension pin 84 protrudes from the upper surface of the drive plate 68, and a spring 94 is mounted between the stop plate 92 at the upper end of the pin and the drive plate 68, and the load (of the top ring body 10 is reduced by the elastic force of the spring 94. Some).
[0023]
Two parallel drive pins 98 are embedded in the holes 90 of the drive plate 68 so as to sandwich the driven pins 86 from both sides of the flange portion 66 in the circumferential direction. In this case, since the driven pin 86 and the drive pin 98 can be relatively moved in the vertical direction even when the holding plate 16 is inclined as will be described later, the contact points are engaged with each other so that the drive shaft 12 is engaged. Is reliably transmitted to the gripping plate 16.
[0024]
Next, the operation of the substrate holding apparatus configured as described above will be described.
By connecting the vacuum source 58 of the external fluid supply device 54 to the rotary joint 52, the substrate is sucked and attached to the lower surface of the gripping plate 16 through the flow hole 38 of the gripping plate 16, and the drive source is operated to drive the drive shaft 12. To rotate the gripping plate 16. In this case, since the flow pipe 56 is made of Teflon or polypropylene, it has a strength that does not cause extreme deformation even when it is in communication with the vacuum source 58.
[0025]
When the top ring cylinder 48 is operated to move the rod 48a in the direction of pulling it into the top ring cylinder body 48, the top ring head 48 is lowered together with the drive shaft holder 46 because the top ring head 42 is fixedly provided. The substrate is brought into contact with the turntable, and the substrate is further pressed against the turntable. That is, the pulling force by the rod 48a is transmitted to the substrate as a pressing force to the substrate through the drive shaft 12, the bearing ball 78, the flange portion 30 of the cover plate 18, and the grip plate 16, and this is transmitted to the polishing cloth on the turntable. Press the top with a constant pressure. On the other hand, the turntable has already started rotating when the top ring body 10 is lowered, and the polishing abrasive liquid is supplied from the polishing abrasive liquid nozzle to the polishing cloth on the turntable. Then, polishing is started by allowing the polishing abrasive liquid to enter the surface to be polished (lower surface) of the substrate.
[0026]
Here, since the pressing force from the drive shaft 12 is transmitted via the spherical bearing 70 formed between the drive shaft 12 and the top ring body 10, for example, the drive is driven with the turntable surface slightly inclined. Even when the perpendicularity between the shaft 12 and the polishing surface of the turntable is impaired, the gripping plate 16 tilts around the bearing ball 78 and as a result, the substrate is brought into close contact with the turntable surface.
[0027]
In addition, a concave portion 24 is formed on the opposite surface of the gripping plate 16 and the covering plate 18 so that the concave portion 24 is fitted on the gripping plate 16 side and the convex portion 28 is fitted on the covering plate 18 side. Since the portion is reduced in thickness and a part of the spherical bearing is located in the recess 24, the distance between the center of the spherical bearing 70 and the surface of the substrate is reduced. Accordingly, the value of the rotational moment around the spherical bearing 70 due to the force acting between the turntable and the substrate is also reduced, and the posture of the substrate is stabilized. Thus, the space for the fluid supply hole of the top ring main body 10 is secured without impairing the rigidity of the gripping plate, and the adhesion between the polishing cloth surface of the turntable and the substrate is maintained and stabilized. Polishing can be performed.
[0028]
Further, since the bearing ball 78 is provided between the recess 32 of the cover plate 18 and the convex portion 76 at the lower end of the drive shaft 12, this also reduces the distance between the center of the spherical bearing 70 and the surface of the substrate. The posture of the substrate becomes stable. In addition, the thickness of the peripheral portion of the top ring main body 10 including the shoulder portion 34 and the stepped surface 36 is secured, so that the rigidity is not impaired, and the connection hole 40 and the driven pin 86 are not damaged. There is ample space for planting.
[0029]
When the polishing is completed, the drive shaft 12 is raised, the top ring body 10 is raised, the top ring body 10 is retracted from the turntable, and is placed on a table that delivers the substrate. At this time, by connecting the vacuum source 58 of the external fluid supply device 54 to the rotary joint 52, the substrate is adsorbed on the lower surface of the gripping plate 16, and then the pure water supply source of the external fluid supply device 54 By connecting 62 to the rotary joint 52, the pure water pushes the substrate from the back surface through the clearance S from the flow pipe 56 and the flow hole 38 of the grip plate 16, so that the substrate is easily peeled from the grip plate 16.
[0030]
In this embodiment, since the pressing force is transmitted from the flange portion 30 of the covering plate 18 to the stepped surface 26 of the gripping plate 16, compared with the conventional configuration in which the pressing force is applied from the bearing ball 78 to the center portion of the gripping plate 16. Thus, the amount of vertical deflection of the gripping plate 16 is reduced by the amount of force applied to the circumference, and the force can be applied uniformly from the gripping plate 16 to the entire surface of the substrate.
[0031]
In this polishing apparatus, since the flow pipe 56 is made of a corrosion-resistant material, the generation of rust in the flow pipe 56 is prevented even if air or water is alternately supplied through the flow pipe 56. Polishing accuracy and quality can be improved without rust mixing into the fluid.
[0032]
【The invention's effect】
According to the present invention, a shaft hole is provided in the central portion of the drive shaft, and a flow pipe made of an appropriate material different from the drive shaft is provided in the shaft hole, and fluid such as pure water is exchanged with the top ring body by the flow pipe. Since it is supplied to the gap with the polishing object, rust formation is prevented by forming the flow pipe with a corrosion-resistant material in particular, and the fluid supplied to the back of the substrate is polished so that it does not contain rust. Accuracy and quality can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an embodiment of a polishing apparatus according to the present invention.
FIG. 2 is a longitudinal sectional view of an upper part of FIG.
FIG. 3 is a plan view of a main part of the embodiment of FIG. 1;
FIG. 4 is a cross-sectional view showing a conventional polishing apparatus.
FIG. 5 is a plan view of FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Top ring main body 12 Drive shaft 16 Grasp board 18 Cover plate 50 Shaft hole 54 Fluid supply apparatus 56 Flow pipe 70 Spherical bearing 72 Transmission mechanism

Claims (5)

A top ring body that grips the substrate facing the turntable; and a drive shaft that supports the top ring body through a spherical bearing so as to be tiltable.
A shaft hole is formed in the central portion of the drive shaft, and one end communicates with an external device such as a fluid source in the shaft hole, and the other end communicates between the top ring body and the polishing object. A distribution pipe is inserted ,
The top ring body includes a grip plate in which a substrate is gripped on the lower surface and a concave portion is formed in the center of the upper surface, and a cover plate in which a convex portion that fits the concave portion is formed in the center of the lower surface.
The spherical bearing is arranged so that at least a part thereof is located inside the concave portion of the gripping plate,
The depth of the concave portion of the grip plate is made larger than the height of the convex portion of the covering plate, and a gap is formed between the concave portion and the convex portion,
The substrate gripping device , wherein the flow pipe communicates with a gap between the concave portion and the convex portion . The grip plate is formed with a flow hole inserted vertically.
The flow tube, a substrate holding apparatus according to claim 1, characterized in that it is communicating with the communication hole of the gripping plate through a gap between the concave portion and the convex portion. 3. The substrate grip according to claim 1, wherein the spherical bearing is provided between a recess formed on a lower surface of the drive shaft and a recess formed on an upper surface of the cover plate. apparatus. 4. The transmission mechanism according to claim 1, further comprising a transmission mechanism that is provided between an end of the drive shaft and the top ring body and transmits a rotational driving force from the drive shaft to the top ring body. The substrate holding apparatus according to claim 1. A turntable having a polishing surface, a polishing apparatus characterized by having a substrate holding apparatus according to any one of claims 1 to 4.

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