JP3647596B2 - Polishing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus characterized by a structure for attaching a turntable to a rotary drive shaft.
[0002]
[Prior art]
In the manufacturing process of a semiconductor wafer, a polishing apparatus is used to flatten and mirror the surface of the semiconductor wafer.
[0003]
This type of polishing apparatus has a turntable and a top ring that rotate at independent rotation speeds, and polishes the surface of the semiconductor wafer held by the top ring with a polishing surface on the top surface of the turntable.
[0004]
Here, FIG. 6 is a schematic sectional side view showing a state in which the conventional turntable 80 is attached to the rotary drive shaft 90. As shown in the figure, the conventional turntable 80 is formed in a substantially disk shape, and a polishing cloth 81 is attached to the upper surface thereof, and a through hole 83 for inserting a center bolt 99 is provided at the center thereof. Yes. A circular fitting recess 85 is provided below the through hole 83.
[0005]
The outer surface of the fitting recess 85 on the lower surface of the turntable 80 is a contact surface 87 formed in a flat shape.
[0006]
Next, the rotational drive shaft 90 is rotationally driven by a motor (not shown) attached to the lower portion of the rotational drive shaft 90. A central projection 91 is provided at the upper end, and an outer surface thereof is a contact surface 93 formed in a flat shape. A screw hole 95 is provided at the center of the central protrusion 91.
[0007]
The turntable 80 is fixed to the rotary drive shaft 90 by fitting the central protrusion 91 of the rotary drive shaft 90 into the fitting recess 85 of the turntable 80 and contacting the contact surfaces 87 and 93 of both. With the rotary drive shaft 90 and the turntable 80 positioned, a center bolt 99 is inserted into the through hole 83 of the turntable 80 and screwed into the screw hole 95 of the central protrusion 91, thereby firmly fixing the two. Is done. Reference numeral 97 denotes a cap.
[0008]
Here, the central protrusion 91 and the fitting recess 85 are fitted together by bringing the outer peripheral side surface of the central protrusion 91 and the inner peripheral side face of the fitting concave portion 85 into close contact with each other when the both are fitted. This is because the axis of the turntable 80 is aligned.
[0009]
On the other hand, a gap a is provided between the upper end surface of the central protrusion 91 and the bottom surface of the fitting recess 85 as shown in the figure. The clearance a is provided if these surfaces are brought into contact with each other, the contact between these surfaces and the contact between the contact surfaces 87 and 93 must be performed at the same time. This is because an error may cause the contact surfaces 87 and 93 to not contact each other. In other words, the gap a is formed in order to reliably contact the direction between the contact surfaces 87 and 93.
[0010]
[Problems to be solved by the invention]
However, in the case of the conventional example, since there is a gap a, as shown in FIG. 7, when the center bolt 99 is strongly tightened, the portion around the center bolt 99 of the turntable 80 is caused by the tightening force. There is a problem that the surface is distorted by being deformed by being pulled in the tightening direction. Specifically, the strain amount b in the thickness direction may reach about 10 μm.
[0011]
If the turntable 80 is deformed, the in-plane uniformity of the wafer to be polished is deteriorated, and the desired performance may not be exhibited.
[0012]
The present invention has been made in view of the above points, and an object of the present invention is to provide a polishing apparatus having a structure in which the surface of a turntable is not distorted even when a bolt is tightened.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a polishing apparatus comprising a turntable for polishing an object to be polished, and a rotary drive shaft fixed by a bolt to the lower surface of the turntable. A member that prevents deformation of the peripheral portion of the bolt of the turntable when the bolt is tightened was installed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the structure and operation of the entire polishing apparatus to which the present invention is applied will be described with reference to FIG.
[0015]
In the figure, a cleaning device 90 is installed beside the polishing device 70. Then, the semiconductor wafer introduced into the cleaning apparatus 90 from the transfer section a of the cleaning apparatus 90 is transferred to the work transfer apparatus 83 of the polishing apparatus 70 and placed thereon.
[0016]
The semiconductor wafer on the workpiece delivery device 83 is delivered to a top ring 75 attached to a polishing unit 77 that rotates as indicated by an arrow A, polished by a polishing cloth on the turntable 10, and then delivered again. It is returned to the device 83, then cleaned and dried in the cleaning device 90, conveyed to the delivery section a, and taken out to the outside.
[0017]
The dressing tool 79 attached to the dressing unit 81 rotates on the turntable 10 as indicated by an arrow B to regenerate (sharp) the polishing cloth on the turntable 10.
[0018]
The turntable 10 is rotationally driven by a rotational drive shaft 50 attached to the center of the lower surface thereof.
[0019]
The gist of the present invention resides in the connection portion between the turntable 10 and the rotary drive shaft 50. FIG. 1 is an enlarged side cross-sectional view of the main part of the connecting portion. FIG. 2 is a plan view of the main part of the turntable 10 as viewed from above with the cap 101 removed.
As shown in FIG. 1, a through hole 11 passing through the turntable 10 up and down is provided at the center of the stainless steel turntable 10 (that is, the rotation center shaft portion). A circular fitting recess 13 is provided, and a bolt housing recess 15 is provided on the upper side. An outer surface of the fitting recess 13 on the lower surface of the turntable 10 is a contact surface 19 formed in a flat shape.
[0021]
In addition, the thin portion 21 between the fitting recess 13 and the bolt housing recess 15 is provided with six screw holes 23 (see FIG. 2) at equal intervals so as to surround the periphery of the through hole 11 in a circumferential shape. .
[0022]
On the other hand, a central protrusion 51 is provided at the upper end of the rotational drive shaft 50, and a screw hole 53 is provided at the center (that is, the rotational central shaft portion). The outer surface of the central protrusion 51 is a contact surface 55 formed in a flat shape. A groove 57 for storing an O-ring 117 is provided at the base of the central protrusion 51.
[0023]
Next, reference numeral 40 shown in FIG. 1 denotes a substantially disc-shaped washer. A through hole 41 is formed in the center of the washer 40 to penetrate the threaded portion 31 of the center bolt 30, and six strain preventing bolts 60 described below are inserted at positions facing the screw hole 23 of the turntable 10. A through hole 43 (see FIG. 2) is provided, and three screw holes 45 (see FIG. 2) are provided at predetermined positions.
[0024]
Next, reference numeral 60 shown in FIG. 1 denotes a distortion preventing bolt. Here, FIG. 3 is an enlarged side sectional view of the distortion preventing bolt 60. As shown in FIGS. 1, 2 and 3, a male screw is cut on the entire outer peripheral side surface of the distortion preventing bolt 60, a hexagon wrench insertion hole 61 is provided on the upper end surface thereof, and a spherical body is provided on the lower end surface thereof. 65 is rotatably attached. The spherical body 65 cuts a part of a metal sphere into a flat shape, thereby forming the flat surface as a pressing surface 67.
[0025]
Next, reference numeral 35 shown in FIG. 1 denotes a contact plate. The contact plate 35 is formed of a flat ring-shaped metal plate having a through hole 37 in the center.
[0026]
Next, reference numeral 101 shown in FIG. 1 denotes a cap that closes and seals the bolt housing recess 15. A female screw 103 for fixing a cap pulling jig is provided at the center of the upper surface of the cap 101, and through holes 103 for inserting mounting bolts 111 are provided at positions facing the three screw holes 45 provided in the washer 40, respectively. It has been. A ring groove 105 for attaching an O-ring 115 is provided on the outer periphery of the cap 101.
[0027]
The turntable 10 is attached to the rotary drive shaft 50 by first placing the contact plate 35 on the central protrusion 51 of the rotary drive shaft 50 and then screwing the six strain prevention bolts 60 into the screw holes 23 in advance. The fitting recess 13 is fitted to the central protrusion 51 by placing the combined turntable 10. At this time, a gap A is generated between the central projection 51 and the fitting recess 13.
[0028]
Next, the washer 40 is inserted into the bolt housing recess 15 of the turntable 10, and then the threaded portion 31 of the center bolt 30 is inserted into the through hole 41 of the washer 40 and the through hole 11 of the turntable 10. Then, the O-ring 117 housed in the groove 57 is crushed by lightly tightening the center bolt 30 to lightly contact the contact surfaces 19 and 55.
[0029]
Next, six strain-preventing bolts 60 previously screwed into the turntable 10 are further screwed, and the pressing surface 67 (see FIG. 3) of the sphere 65 is brought into contact with the contact plate 35. Let
[0030]
Next, the center bolt 30 is further screwed in and tightened firmly to secure the turntable 10 to the rotary drive shaft 50.
[0031]
At this time, the force around the center bolt 30 of the turntable 10 is pulled in the tightening direction of the center bolt 30 due to the tightening force of the center bolt 30, and there are six forces around the center bolt 30. The distortion preventing bolt 60 supports the force to be deformed. Therefore, distortion of the surface of the turntable 10 can be prevented. According to actual measurement, the amount of strain in the thickness direction was 1 μm or less.
[0032]
Finally, the cap 101 is attached so as to close the bolt housing recess 15, the three attachment bolts 111 are inserted into the three through holes 103, and each attachment bolt 111 is screwed into the screw hole 45 of the washer 40 and fixed. .
[0033]
The reason why the bolt housing recess 15 is sealed by attaching the cap 101 is to prevent the center bolt 30 made of high-strength steel from being easily rusted.
[0034]
Note that the pressing surface 67 of the sphere 65 that presses the contact plate 35 is formed in a flat shape, and the sphere 65 is rotatably attached to the distortion preventing bolt 60. Even if the abutting plate 35 is inclined with respect to the distortion preventing bolt 60, the distortion preventing bolt 60 can press the abutting plate 35 with the surface, and the force can be distributed. The pressing force can be made uniform. That is, by this, the six distortion preventing bolts 60 uniformly support the force that the turntable 10 tries to deform and reliably prevent the distortion.
[0035]
Next, FIG. 4 is an enlarged side sectional view (the same part as FIG. 1) of a main part of another embodiment in which a tightening force detecting means is provided on the center bolt 30 in order to make the tightening force of the center bolt 30 constant. is there.
[0036]
In this embodiment, the difference from the above-described embodiment is that the tightening force detection means is equally spaced at six locations in the circumferential direction on the outer peripheral side surface of the upper portion of the screw portion 31 of the center bolt 30 (only two locations are shown in the figure) This is only the point where the strain gauge 130 is pasted on.
[0037]
The output cable 131 of each strain gauge 130 is guided into the recess 34 of the head 33 of the center bolt 30 through a small hole 133 provided in the center bolt 30.
[0038]
When the center bolt 30 is screwed in, the output cable 131 is pulled out and connected to a measuring machine, and the tightening force is measured by the measuring machine while the center bolt 30 is screwed in. It can be optimized.
[0039]
The contact plate 35 is not necessarily required, and the tip of the distortion preventing bolt 60 may be directly contacted with the upper end surface of the central protrusion 51.
[0040]
In the above embodiment, the distortion preventing bolt 60 is attached to the turntable 10 side, but conversely, the distortion preventing bolt 60 may be attached to the rotary drive shaft 50 side to press the turntable 10. In addition, the turntable 10 and the rotary drive shaft 50 are simultaneously connected by tightening the center bolt 30 in a state where a distortion preventive member corresponding to the strain prevention bolt 60 is inserted between the turntable 10 and the rotary drive shaft 50. You may comprise so that it may press with this member for distortion prevention.
[0041]
【The invention's effect】
As described above in detail, according to the present invention, even if the bolt (center bolt) is tightened, the portion around the bolt of the turntable is not distorted by the tightening force, and thereby the surface of the polishing object to be polished. It has an excellent effect that the inner uniformity is maintained and desired performance can be exhibited.
[0042]
Further, since the strain gauge is attached to the bolt, the tightening force of the bolt can be easily detected, and the tightening force can be easily made appropriate.
[Brief description of the drawings]
FIG. 1 is an enlarged side sectional view of a main part of a connection portion where a turntable 10 is attached to a rotary drive shaft 50. FIG.
2 is a plan view of the main part of the center of the turntable 10 as viewed from above with the cap 101 removed. FIG. 3 is an enlarged side sectional view of the distortion preventing bolt 60. FIG.
4 is an enlarged side cross-sectional view of a main part of another embodiment in which a tightening force detection means is provided on the center bolt 30. FIG.
FIG. 5 is a schematic plan view showing a polishing apparatus.
6 is a schematic sectional side view showing a conventional example in which a turntable 80 is attached to a rotary drive shaft 90. FIG.
7 is an enlarged side cross-sectional view of a main part of a connection portion where a turntable 80 is attached to a rotary drive shaft 90. FIG.
[Explanation of symbols]
10 Turntable 13 Fitting recess 19 Contact surface 30 Center bolt (bolt)
50 Rotation drive shaft 51 Center protrusion 55 Contact surface 60 Strain prevention bolt (member)
65 Sphere 67 Pressing surface 75 Top ring 130 Strain gauge A Clearance

Claims (4)

In a polishing apparatus comprising: a turntable for polishing a polishing object; and a rotary drive shaft that is fastened and fixed to the lower surface of the turntable by a bolt.
A polishing apparatus characterized in that a member for preventing deformation of a peripheral portion of the bolt of the turntable when the bolt is tightened is provided in the vicinity of the bolt. The tightening and fixing structure between the turntable and the rotation drive shaft is provided with a fitting recess on the lower surface of the turntable, a center protrusion on the upper end of the rotation drive shaft, and the center protrusion and the fitting recess are fitted and tightened. It is a tightening and fixing structure that is fixed,
The said member is arrange | positioned so that it may be arrange | positioned in the part of the clearance gap which arises in the opposing surface of the said fitting recessed part bottom face and the center protrusion upper end surface, and it may be installed so that the clamping force added between a turntable and a rotational drive shaft may be supported. Item 10. The polishing apparatus according to Item 1. The polishing apparatus according to claim 1 or 2, wherein a sphere having a pressing surface obtained by cutting a part of the sphere into a flat shape is rotatably attached to the tip of the member. The polishing apparatus according to claim 1 or 2, wherein a strain gauge is attached to an outer peripheral side surface of the bolt.

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