JP3427670B2 - Polishing apparatus and polishing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus capable of satisfactorily polishing a surface to be polished such as a wafer, a polishing method, a polishing pad used for polishing, and a polishing pad. It relates to a forming method.

[0002]

2. Description of the Related Art In an LSI manufacturing process, for example, it is important to flatten an interlayer insulating film or another film. Various means have been proposed as a technique for flattening, but in recent years, a CMP (Chemical Mechanical Polishing) method to which a mirror polishing technique for a silicon wafer is applied has attracted attention and is utilized. Have been developed.

[0003]

However, the conventional wafer flattening technique using the CMP method is an extension of the lapping technique. That is, the area of the polishing pad is considerably larger than that of the wafer, and the rotation speed of the polishing pad is slow. Therefore, there is a problem in that the surface flatness of the wafer, the uniformity of the polishing amount within the wafer surface, and the stability of the polishing rate, which is the polishing amount per unit time, are insufficient. There is also a problem that throughput is slow.

That is, if the contact area of the polishing pad with respect to the wafer is considerably large, the effective area of the polishing surface of the polishing pad fluctuates, the amount of polishing of the convex portions on the wafer surface increases, and the amount of polishing of the concave portions decreases. Further, since the peripheral speeds of the polishing pad are greatly different between the outer peripheral side and the inner peripheral side, the polishing amount is smaller on the inner peripheral side, and the polishing amount becomes larger toward the outer peripheral side.
Furthermore, the amount of slurry and polishing material supplied between the polishing pad and the wafer during polishing differs between the inner peripheral side and the outer peripheral side of the polishing pad. Therefore, if the polishing amount is non-uniform and the polishing rate is unstable due to the above reasons, it is difficult to control the polishing apparatus numerically to perform highly accurate polishing. On the other hand, if the contact area of the polishing pad with the wafer is considerably large, the friction between the wafer and the polishing pad becomes large, the polishing pad is abraded, and the polishing pad needs to be replaced frequently. It also has the disadvantage of being prone to clogging.

The present invention has been made in view of the above circumstances, and it is possible to stabilize the amount of polishing and the polishing rate in the surface to be polished of the object to be polished such as a wafer, and to prevent the abrasion of the polishing pad. An object of the present invention is to provide a polishing apparatus, a polishing method, and a polishing pad that can be suppressed as much as possible.

[0006]

A polishing apparatus according to the present invention comprises a holding means for holding and rotating an object to be polished, and the polishing object.
A rotation axis arranged in a direction substantially orthogonal to the target holding surface,
It has a ring-shaped polishing surface for polishing the surface to be polished , and is attached to the lower surface of the surface plate fixed to the rotating shaft.
It is a polishing pad, a rotary drive means for rotating the rotary shaft, moving means for dimensionally relative movement in a certain direction and a ring-shaped polishing surface of the polishing pad and the surface to be polished of the polishing target mutually sliding contact And the rotating shaft is inclined at a predetermined minute angle with respect to an axis orthogonal to the holding surface of the object to be polished held by the holding means, and the ring-shaped polishing surface is It is inclined at the predetermined minute angle with respect to a plane orthogonal to the rotation axis.

In the polishing apparatus of the present invention, the polishing surface of the polishing pad is rotated by the rotation driving means in a state of being inclined with respect to the surface to be polished. Therefore, the narrow portion of the polishing surface of the polishing pad is brought into sliding contact with the surface to be polished, and the surface to be polished is polished. Further, the moving unit moves the sliding contact portion between the rotating polishing target surface of the polishing target and the polishing surface of the polishing pad. As a result, the entire surface to be polished is polished. The polishing pad of the present invention refers to a polishing tool composed of a porous viscoelastic material such as foamed polyurethane or a polishing cloth such as a nonwoven fabric, a polishing wheel, a polishing tool having fixed abrasive grains such as a polishing wheel or a laminated film. Hereinafter, these are collectively referred to as a polishing pad.

[0008] The polishing method of the present invention, a polishing pad having a ring-like abrasive surface facing to the surface to be polished of the polishing target to rotate by rotating, polished surface of the object to be polished by the polishing surface of said polishing pad A polishing method for polishing, wherein the rotation axis of the polishing pad is inclined at a predetermined minute angle with respect to an axis orthogonal to the surface to be polished of the object to be polished, and the ring-shaped polishing surface is the rotation axis. The ring-shaped polishing surface of the polishing pad is slid on the surface to be polished of the object to be polished by inclining at a predetermined minute angle with respect to an orthogonal surface, and the object to be polished and the polishing pad are And are relatively moved in a fixed direction to polish the surface to be polished.

In the polishing method of the present invention, the sliding contact area between the polishing surface of the polishing pad and the surface to be polished is narrowed, and the amount of polishing and the polishing rate in the surface to be polished can be stabilized.

In the polishing pad of the present invention, the polishing surface for slidingly contacting the surface to be polished of the object to be polished and polishing the surface to be polished is inclined at a predetermined angle with respect to the plane orthogonal to the rotation axis.

In the polishing pad of the present invention, since the polishing surface is inclined with respect to the plane orthogonal to the rotation axis, the rotation axis is inclined and the polishing pad is held and rotated, whereby the inclined polishing surface is rotated. A small part comes into sliding contact with the surface to be polished of the object to be polished.

The method of forming a polishing pad according to the present invention is a method of forming a polishing pad in a state where a rotation axis is inclined at a predetermined angle with respect to an axis orthogonal to a holding surface on which an object to be polished to be polished is held. While rotating, while bringing the polishing pad into contact with a facing tool for finishing the polishing surface of the polishing pad provided at a predetermined position of the holding surface,
The polishing pad is relatively moved in a direction along the holding surface to form a polishing surface of the polishing pad.

In the method for forming a polishing pad according to the present invention, the positional relationship in which the holding surface of the object to be polished and the rotation axis of the polishing pad are inclined is easily and highly accurately transferred to the polishing surface of the polishing pad. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall perspective view of a polishing apparatus according to an embodiment of the present invention. A polishing apparatus 30 according to the present embodiment shown in FIG. 1 is for polishing a surface to be polished of a wafer to be polished. It is a device. Also, FIG.
2A and 2B are schematic configuration diagrams of a drive mechanism unit and a wafer holding mechanism unit of the polishing pad of the polishing apparatus shown in FIG. 1, where FIG. 3A is a top view, FIG. 2B is a front view, and FIG. FIG. 3 is a cross-sectional view of essential parts near the polishing pad, and FIG. 4 is a bottom view of the polishing pad.

As shown in FIG. 1, the rotary drive mechanism portion of the main spindle for holding the polishing pad 8 of the polishing apparatus 30 is capable of moving the main spindle 32 for rotating the polishing pad 8 and the main spindle 32 in the Z-axis direction. The Z-axis slider 73 held at the position, a load cell 81 having one end fixed to two positions on the upper surface of the Z-axis slider 73 for detecting a load, and the other end of the load cell 81 fixed to be movable in the Z-axis direction. The sub-slide 82 supported by the sub-slide 82 and a Z-axis drive motor 74 that drives the sub-slide 82 in the Z-axis direction are mainly configured. Further, the movement holding mechanism section for holding and moving the wafer W of the polishing apparatus 30 is mainly configured by the X-axis table 6.

The Z-axis slider 73 is movable in the Z-axis direction along a Z-axis guide 72 provided on the side surface of the column 71. The movement of the Z-axis slider 73 causes the spindle spindle 32 to move in the Z-axis direction. The load cell 81 whose one end is fixed to the Z-axis slider 73 is
Detects the load applied in the axial direction. The other end of the load cell 81 is fixed to the sub slide 82.
Z together with the Z-axis slider 73 while being held by
Performs axial movement. In the load cell 81, as shown in FIG. 2, the point of action P on the Z-axis slider 73 is the center O of the spindle.
It is fixed to the Z-axis slider 73 so as to be aligned with the Z-axis guide 72.

The sub-slide 82, as shown in FIG.
The sub-slide 82 is movable along the sub-slide guide 74a in the Z-axis direction. The sub-slide 82 is driven by a Z-axis drive motor 74 connected to a ball screw 87 screwed in the Z-axis direction via a coupling 89. Driven in the Z-axis direction.

Further, as shown in FIGS. 1 and 2, one ends of two wires 84 are connected to both ends of the upper surface of the Z-axis slider 73, respectively. As shown in FIG. 2, counterweights 86 are respectively connected to the other ends of these wires 84, and these counterweights 86 are suspended via a pulley 83. The load of the counterweight 86 is almost equal to the load of the Z-axis slider 73, and thus the load of the Z-axis slider 73 applied to the load cell 81 is almost canceled, and the load applied to the load cell 81 is reduced. Has been reduced.

The main spindle 32 has a Z-axis slider 73.
It is held by and can be moved in the Z-axis direction. The axis O of the main spindle 32 is inclined at a predetermined angle with respect to the table axis orthogonal to the wafer holding surface of the X-axis table 6. Axis O of main spindle 32
To incline, for example, when fixing the main spindle 32 to the Z-axis slider 73, it is installed so as to incline at a predetermined angle with respect to the Z-axis direction. The tilt angle can be adjusted when the Z-axis slider 73 is installed on the Z-axis guide 72. For example, the tilt angle is adjusted by adjusting the tightening force between the main spindle 32 and the Z-axis slider 73 fastening bolt. In addition, the order of the inclination angle is, for example, per 100 mm in the Z-axis direction, several μm in the direction orthogonal to this.
It is on the order of inclining, and is a minute angle.

The main spindle 32 has a main spindle 36 and a main spindle housing 38, as shown in FIG. A surface plate 34 is attached and fixed to a lower portion of the main shaft 36. A nozzle hole 42 is formed in the center of the surface plate 34, and the nozzle hole 42 is inserted so that the lower end of the nozzle tube 40 does not come into contact with the nozzle hole 42. Slurry as a polishing liquid is discharged from the nozzle tube 40. The nozzle tube 40 does not rotate, and the surface plate 34 is rotatable by the main shaft 36. The main shaft 36 is rotationally driven by a motor (not shown). As the slurry supplied from the nozzle tube 40, a polishing slurry that enables chemical mechanical polishing is used. For example, powdery silicon oxide (
An aqueous solution of SiO ₂ ) and potassium hydroxide (KOH) is used. As shown in FIGS. 3 and 4, in the present embodiment, the nozzle hole 42 has the end plate 4 for slurry distribution at the lower part thereof.
It is formed on the surface plate 34 so that 6 is left. Moreover, radial grooves 44 are formed on the lower surface of the surface plate 34, and the central portions of the radial grooves 44 communicate with the nozzle holes 42.

The X-axis table 6 is rotatably mounted on a slider movably provided in the X-axis direction along a rail (not shown). Since the X-axis table 6 rotates at a relatively low speed, it is rotationally driven by a motor, a pulley, a flat belt and the like. The size of the X-axis table 6 is not particularly limited, but is, for example, a disk shape having a diameter of about 200 mm. A chuck composed of a porous member or the like is mounted on the upper portion of the X-axis table 6. A vacuum evacuation passage is formed along the axis of the rotary shaft that rotates the X-axis table 6. By drawing a vacuum through this passage, the wafer W is vacuum-adsorbed on the surface of the X-axis table 6.

As shown in FIGS. 3 and 4, a ring-shaped polishing pad 8 is attached to the outer periphery of the lower surface of the surface plate 34 by adhesion or the like. The center of rotation of the ring-shaped polishing pad 8 coincides with the axis O of the spindle spindle 32 and the spindle 36, and the polishing surface 8a of the polishing pad 8 has an axis center of the spindle spindle 32, as will be described later. It is inclined at a predetermined angle with respect to the plane orthogonal to O. The inclination angle of the polishing surface 8a is equal to the inclination angle of the axis O of the main spindle 32.
The polishing pad 8 is made of a porous viscoelastic material such as foamed polyurethane. Outer diameter D of this polishing pad 8
Is an outer diameter that is substantially the same as or smaller than the outer diameter of the wafer W. The radial grooves 44 described above are formed so as to extend to the inner peripheral surface of the polishing pad 8. The radial width d of the ring-shaped polishing pad 8 is 20 mm in this embodiment. The outer diameter D of the surface plate 34 is 200 mm.

Further, as shown in FIG.
Holds, by vacuum suction, an unpolished wafer W stored in a wafer cassette 61 carried by a carrier device (not shown), carries it to the load buffer 63, and waits for the wafer W on the X-axis table 6. When the polishing is completed and unloaded, the loader chuck 55 that loads the wafer W on the load buffer 63 onto the X-axis table 6 through the opening 90 of FIG. 1 and the wafer W that has been polished on the X-axis table 6 are loaded. The wafer cassette 67 is cleaned by vacuum suction through the opening 90 and carries the unloader chuck 64 to the unload buffer 65 and the surface of the wafer W placed on the unload buffer 65.
And a wafer cleaning brush 66 to be housed in.

Next, the operation of the polishing apparatus 30 according to this embodiment will be described. First, the unpolished wafer W stored in the wafer cassette 61 is placed on the load buffer 63 by the loader chuck 55. After the polishing of the wafer W on the X-axis table 6 is completed, the unloader chuck 6
When unloaded by 5, the loader chuck 55 carries the wafer W placed on the load buffer 63 onto the X-axis table 6 and places the wafer W to be polished with the surface to be polished facing up in the figure. Then, the suction device of the X-axis table 6 starts suction, a suction force is generated on the surface thereof, and the wafer W placed on the X-axis table 6 is suctioned to the X-axis table 6.

Next, by driving the main spindle 32, the surface plate 34 is rotated at a rotational speed of, for example, 1000 to 3000.
Rotate at high speed of rpm. Further, the X-axis table 6 is rotated together with the wafer W by driving the motor at a low speed of several tens rpm, for example. Further, a slider provided so as to be movable in the X-axis direction along a rail (not shown) is moved in the X-axis direction along the rail so that the polishing pad 8 is located above the wafer W. At this time, the slurry from the slurry supply device is discharged from the nozzle hole 42 via the nozzle pipe 40 shown in FIG. 3, and is supplied to the inner peripheral side of the polishing pad 8 through the radial 44 by the centrifugal force due to the rotation. .

Then, the spindle spindle 32 is lowered to a predetermined position in the Z-axis direction by driving the Z-axis drive motor 74. As a result, the polishing pad 8 is applied to the surface to be polished of the wafer W.
A part of the polishing surface 8a of the above contacts. In this state, a slider (not shown) reciprocates the X-axis table 6 along the rail at a predetermined cycle and amplitude by a driving force from a driver (not shown), and the wafer W traverses the polishing pad 8 ( Reciprocating movement in the radial direction of rotation). The speed of this traverse motion is, for example, 5 to 400.
(Mm / min). During this traverse movement, the polishing pad 8 and the wafer W rotate together.

Here, FIG. 5 shows a state in which polishing is carried out with a part of the polishing surface 8a of the polishing pad 8 contacting the surface to be polished of the wafer W. As shown in FIG. 5, the axis O of the main spindle 32, which is the center of rotation of the polishing pad 8, is
Table axis T orthogonal to the wafer holding surface of the X-axis table 6
It is in a state of being inclined at a small inclination angle θ. On the other hand, the polishing surface 8a of the polishing pad 8 is also inclined at the same angle as the inclination angle θ with respect to the surface orthogonal to the axis O of the main spindle 32. The facing process of the polishing surface 8a of the polishing pad 8 will be described later. The tilt angle θ is
Although it is shown large in the drawings for the sake of convenience of explanation, in reality, the main axis 36 is a minute angle that inclines on the order of several μm per 100 mm.

In FIG. 5, the polishing pad 8 is rotating at a high speed in the direction of arrow D, the wafer W is rotating at a low speed in the direction of arrow C, and the polishing surface 8a of the polishing pad 8 and the wafer W are covered. The sliding surface makes sliding contact with the polishing surface. This sliding contact part S
At, the surface of the wafer W to be polished is polished.

Further, the polishing pad 8 is pressed against the surface to be polished of the wafer W with the processing pressure L. The processing pressure L of the polishing pad 8 on the surface to be polished of the wafer W can be adjusted by driving the Z-axis drive motor 74 described above. That is, when the Z-axis drive motor 74 is driven, the load cell 81 detects a force corresponding to the processing pressure L of the polishing pad 8 on the surface to be polished of the wafer W. By controlling the Z-axis drive motor 74 based on the detection signal of the load cell 81, the processing pressure L can be adjusted.

Polishing surface 8a of polishing pad 8 in FIG.
6, is formed at the same angle as the inclination angle θ of the axis O of the main shaft 36 with respect to the table axis T. Therefore, the shape of the sliding contact portion S shown in FIG. 5 changes as shown in FIG. 7, for example, by changing the magnitude of the processing pressure L. When the processing pressure L is small, as shown in FIG. 7A, the sliding contact portion S has a tangential shape having a very small area as compared with the entire polishing surface 8a. As the processing pressure L is increased, the sliding contact portion S expands in a fan shape as shown in FIG. This is because the polishing pad 8
This is because elastic deformation occurs on the polishing surface 8a.

Further, when the processing pressure L is increased,
As shown in FIG. 7C, the fan-shaped sliding contact portion S further expands. That is, when the processing pressure L is increased,
The axis O of the ring-shaped polishing pad 8 is not inclined with respect to the table axis T, and the polishing surface 8a approaches a state similar to the sliding contact when parallel to the surface to be polished of the wafer W. I understand. Therefore, in this embodiment, by adjusting the processing pressure L, the area of the sliding contact portion S between the polishing surface 8a and the surface to be polished of the wafer W can be narrowed to an appropriate range.

The amount of polishing of the surface to be polished of the wafer W by the polishing surface 8a of the polishing pad 8 is an amount corresponding to the area of the sliding contact portion S. That is, the polishing amount is small when the area of the sliding contact portion S is small, and the polishing amount is large when the area of the sliding contact portion S is large. Therefore, the polishing amount can be adjusted by adjusting the processing pressure L and the area of the sliding contact portion S.

The area of the sliding contact portion S can be changed by adjusting the inclination angle θ of the main shaft 36 and the inclination angle θ of the polishing surface 8a of the polishing pad 8 in addition to the method of adjusting the processing pressure L. . That is, under a constant processing pressure L, the larger the inclination angle θ of the main shaft 36 and the polishing surface 8a of the polishing pad 8, the more the sliding contact portion S becomes tangential, and the smaller the inclination angle θ, the smaller the sliding contact portion. The shape of S becomes a fan shape. Therefore, the Z-axis slider 73 of the polishing apparatus 30
It is possible to adjust the polishing amount by adjusting the inclination angle θ in advance when the Z is installed on the Z-axis guide 72. In addition,
It is also possible to equip the polishing apparatus 30 with a tilting mechanism capable of changing the tilt angle of the Z-axis slider 73 in real time. In this case, the area of the sliding contact portion S can be changed in real time.

As described above, the axis O of the main shaft 36 and the polishing surface 8a of the polishing pad 8 are inclined, and only a small portion of the polishing surface 8a is slidably brought into contact with the surface to be polished of the wafer W for polishing. The surface of the wafer W to be polished has a chemical polishing action due to an alkaline component in the slurry supplied from the nozzle tube 40, a mechanical polishing action due to polishing particles such as silica having a diameter of about 0.1 μm, and further Due to the synergistic polishing action, mechanochemical polishing (CMP) is favorably performed.

At this time, since the sliding contact portion S can be made to have a minute area, it is less likely to be affected by the unevenness of the surface to be polished of the wafer W. Therefore, the area of the sliding contact portion S can be stabilized during the polishing process, and the uniformity of the polishing amount can be significantly improved. Further, since the sliding contact portion S can have a small area, the slurry distribution becomes stable in the sliding contact portion S. Therefore, the fluctuation of the polishing rate, which is the polishing amount per unit time, becomes extremely small.
Therefore, the uniformity of the polishing rate can be significantly improved. Further, by performing polishing using the ring-shaped polishing pad 8, the radial length of the polishing surface 8a becomes shorter,
There is almost no difference in peripheral speed in the sliding contact portion S, and variation in the polishing amount is suppressed to the minimum. Further, since the sliding contact portion S has a minute area, a sufficient surface pressure can be obtained even if the absolute value of the processing pressure L is very small.

When the polishing process by the polishing apparatus 30 is completed, the wafer W is carried from the opening 30 shown in FIG. 1 to the unload buffer 65 by the unloader chuck 64, cleaned by the wafer cleaning brush 66, and then the wafer cassette 67. Is stored in.

As described above, in this embodiment, the sliding contact portion S
Since the polishing amount and the polishing rate are stable and the absolute value of the processing pressure L may be very small, it becomes very easy to control the polishing amount. That is, for example, by adjusting the processing pressure L or the inclination angle θ of the axis O of the main shaft 36 to adjust the area of the sliding contact portion S, the amount of polishing in the surface to be polished of the wafer W can be controlled, or the wafer W can be controlled. When the polishing amount is controlled by adjusting the feed rate of the X-axis table that holds the machining amount, there is almost no variation or fluctuation in the polishing amount and the polishing rate at the sliding contact portion S, so the processing pressure L and the axis O The desired polishing accuracy can be easily obtained even if the inclination angle θ of the above and the feed rate of the X-axis table are numerically controlled.

Further, in this embodiment, since a very small part of the polishing surface 8a of the polishing pad 8 is in sliding contact with the surface to be polished of the wafer W, the polishing pad 8 is hardly worn and the polishing pad 8 has a long life. Can be realized. Further, since a part of the polishing surface 8a of the polishing pad 8 is in sliding contact with the surface to be polished of the wafer W, the rate of clogging of the polishing surface 8a of the polishing pad 8 is significantly reduced.

Further, the polishing pad 8 of this embodiment is shown in FIG.
As shown in (a), basically, the rotation axis of the polishing pad 8 is substantially orthogonal to the surface to be polished of the wafer W, and the surface to be polished of the wafer W is covered by the surface to be polished 8a facing the surface to be polished of the wafer W. This is a polishing method for polishing the polishing surface. Since the sliding contact portion of the polishing surface 8a with the surface to be polished of the wafer W has an arc shape (fan shape), even if the polishing surface 8a has irregularities, the surface to be polished of the wafer W has random irregularities. Will be formed.
Therefore, in the present embodiment, the flatness of the surface to be polished of the wafer W after polishing is good. On the other hand, as shown in FIG. 8B, the rotation axis of the polishing pad 101 is parallel to the surface to be polished of the wafer W, and the surface to be polished of the wafer W is fixed by the polishing surface 101a which is the outer peripheral surface of the polishing pad 101. In the case of the polishing method of polishing, the unevenness of the polishing surface 101a is
Since it is directly transferred to the surface to be polished, the surface property of the surface to be polished of the wafer W after polishing is poor.

Further, in this embodiment, the flatness due to polishing is improved by using the ring-shaped polishing pad 8.
Conventionally, on the inner peripheral side and the outer peripheral side of the disk-shaped polishing pad,
Since the difference in the peripheral speed of the pad is large, the difference in the frequency of the exciting force due to the step processed in those parts is large.
For this reason, for example, if the polishing pad rotation speed is such that a step can be conveniently processed on the inner peripheral side, there is a risk that the remaining processing of the step will be large on the outer peripheral side. In this embodiment, by using the ring-shaped polishing pad 8,
The difference in peripheral speed between the inner and outer circumferences can be reduced, the uniformity of the polishing ability is improved, and the flatness of the resulting surface to be polished is improved.

Here, the polishing surface 8 of the polishing pad 8 described above.
The method of forming a will be described. First, the polishing pad 8 is mounted on the surface plate 34 of the spindle 36 of the polishing device 30.
As a result, the axis O of the polishing pad 8 is tilted at the tilt angle θ with respect to the table axis T of the X-axis table 6 as shown in FIG. 9A.

Next, as shown in FIG. 9B, the facing tool B is fixed to a predetermined position of the X-axis table 6. As the facing tool B, for example, a facing tool such as a diamond bite can be used. Then, as shown in FIG. 9C, the X-axis table 6 is moved in the X-axis direction to bring the end face portion of the polishing pad 8 into contact with the facing tool B, and the polishing pad 8 is self-cut. As a result, a polishing surface 8a that is inclined at an inclination angle θ with respect to the surface of the polishing pad 8 that is orthogonal to the axis O is formed.

The polishing pad 8 is mounted on the polishing apparatus 30 which actually performs polishing, and the polishing surface 8a is formed by using the facing tool B, whereby the inclination angle θ of the axis O with respect to the table axis T is adjusted. 8 can be accurately transferred to the polishing surface 8a. By performing a polishing process with the polishing pad 8 formed by the above method,
It is possible to further improve the uniformity of the polishing amount and polishing rate at the sliding contact portion S. Further, according to the above method, the polishing surface 8a of the polishing pad 8 according to the present embodiment can be easily and highly accurately formed.

The present invention is not limited to the above-mentioned embodiment, but can be variously modified within the scope of the present invention. For example, in the above embodiment, the main shaft 36 is tilted at the tilt angle θ with respect to the table axis T of the X-axis table 6, but the main shaft 36 is not tilted but the wafer holding surface of the X-axis table 6 is tilted. It is also possible to tilt at an angle θ. Further, although the wafer W is moved with respect to the polishing pad 8 by moving the wafer W in the X direction by the X-axis table 6, the main spindle 32 for holding the polishing pad 8 is reciprocally moved with respect to the wafer. Is also good. However, since the spindle 32 rotates at a higher speed, it is preferable to reciprocate the table 6 from the viewpoint of rotational stability.

[0045]

As described above, according to the present invention, since the polishing pad is inclined and a part of the polishing surface is slidably contacted with the surface to be polished of the object to be polished, the sliding contact portion is made fine. The area can be made smaller, and the area is less likely to be affected by the unevenness of the surface to be polished. Therefore, the effective area of the sliding contact portion can be stabilized during polishing, and the uniformity of the polishing amount can be significantly improved. Further, since the sliding contact portion can have a minute area, the distribution of the abrasive such as slurry is stabilized in the sliding contact portion. Therefore, the fluctuation of the polishing rate per unit time becomes very small.
Therefore, the uniformity of the polishing rate can be significantly improved. Further, by performing polishing using a ring-shaped polishing pad, the radial length of the polishing surface is shortened, there is almost no peripheral speed difference in the sliding contact portion, and variation in polishing amount is minimized. Further, since the sliding contact portion has a very small area, a sufficient surface pressure can be obtained even if the absolute value of the processing pressure is very small.

As a result, it becomes very easy to control the amount of polishing within the surface to be polished, and it is possible to perform numerically controlled polishing easily and with high precision, and to perform polishing of any curved surface. Highly accurate polishing process can be automated.

Further, according to the present invention, since a very small part of the polishing surface of the polishing pad is in sliding contact with the surface to be polished of the object to be polished, the abrasion of the polishing pad is very small, and the abrasion of the surface of the polishing pad is small. The clogging rate is also greatly reduced, and the life of the polishing pad can be extended.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a polishing apparatus according to an embodiment of the present invention.

2A and 2B are schematic configuration diagrams of a rotation drive mechanism unit of a polishing pad and a wafer movement holding mechanism unit of the polishing apparatus shown in FIG. 1, in which FIG. 2A is a top view, FIG. 2B is a front view, and FIG. It is a side view.

FIG. 3 is a cross-sectional view of essential parts near a polishing pad.

FIG. 4 is a bottom view of the polishing pad.

FIG. 5 is a perspective view showing a state in which polishing is performed with a part of the polishing surface of the polishing pad in contact with the surface to be polished of the wafer.

6 is a sectional view showing a positional relationship between the wafer shown in FIG. 5 and a polishing pad.

FIG. 7 is an explanatory diagram showing a change in the shape of the sliding contact portion S by changing the magnitude of the processing pressure, where (a) is a small processing pressure and (b) is an increased processing pressure. In the case of (c), the processing pressure is further increased.

8A is an explanatory view showing a basic polishing method of the present invention, and FIG. 8B is an explanatory view showing another polishing method.

9A and 9B are explanatory views for explaining a method for forming a polishing surface of a polishing pad according to the present invention, in which FIG. 9A is a diagram showing a state in which a polishing pad is mounted on a spindle, and FIG. It is a figure which shows the state which fixed the facing tool to the axis | shaft table, (c) is explanatory drawing which shows a mode that the X-axis table is moved and a polishing surface is formed by a facing tool.

[Explanation of symbols]

6 ... X-axis table, 8 ... Polishing pad, 8a ... Polishing surface, 3
0 ... Polishing device, 32 ... Main spindle, 72 ... Z-axis guide, 73 ... Z-axis slide, 74 ... Z-axis drive motor, 81
… Load cell, 82… Sub slide.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-17758 (JP, A) JP-A-7-88759 (JP, A) JP-A-8-99265 (JP, A) JP-A-9- 94757 (JP, A) JP 60-221259 (JP, A) JP 60-249562 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B24B 37/04 H01L 21 / 304 B24B 37/00

Claims (10)

(57) [Claims] 1. A holding means for holding and rotating an object to be polished and a holding means arranged in a direction substantially orthogonal to a holding surface of the object to be polished.
It has a rotating shaft and a ring-shaped polishing surface for polishing the surface to be polished , and is mounted on the lower surface of a surface plate fixed to the rotating shaft.
It is a polishing pad, a rotary drive means for rotating the rotary shaft, moving means for dimensionally relative movement in a certain direction and a ring-shaped polishing surface of the polishing pad and the surface to be polished of the polishing target mutually sliding contact And the rotating shaft is inclined at a predetermined minute angle with respect to an axis orthogonal to the holding surface of the object to be polished held by the holding means, and the ring-shaped polishing surface is A polishing apparatus that is inclined at the predetermined minute angle with respect to a plane orthogonal to the rotation axis. Wherein said rotary drive means, the polishing apparatus according to claim 1 which is arbitrarily adjustable inclination angle relative to the holding surface of the holding means before Kikai rotating shaft. 3. The polishing apparatus according to claim 1, further comprising pressure adjusting means for adjusting a processing pressure of the ring-shaped polishing surface of the polishing pad with respect to the surface to be polished. 4. The polishing apparatus according to claim 1, further comprising a polishing liquid supply means for supplying a polishing liquid that causes chemical mechanical polishing between the polishing pad and the object to be polished. 5. A surface to be polished that faces a rotating object to be polished is faced.
A polishing method for rotating a polishing pad having a ring-shaped polishing surface to polish the surface to be polished of the object to be polished by the polishing surface of the polishing pad, wherein the rotation axis of the polishing pad is to be the surface of the object to be polished. is a predetermined minute angle inclined relative to the axis perpendicular to the polishing surface, and the tilted at a predetermined minute angle the ring-shaped polishing surface relative to a plane perpendicular to the rotation axis, ring-shaped polishing of the polishing pad A polishing method in which a surface is brought into sliding contact with a surface to be polished of the object to be polished, and the object to be polished and the polishing pad are relatively moved in a predetermined direction to polish the surface to be polished. 6. Prior to polishing of the object to be polished, a ring-shaped polishing surface of the polishing pad is faced in advance so as to be inclined at a predetermined minute angle with respect to a surface orthogonal to the rotation axis of the polishing pad, The polishing method according to claim 5 , wherein the polished surface to be polished is polished with the facing ring-shaped polishing surface. 7. The polishing pad facing the ring-shaped polishing surface of the polishing pad rotates in a state where the rotation axis is inclined at a predetermined minute angle with respect to an axis orthogonal to the surface to be polished of the object to be polished. ring of the ring-shaped grinding surface is brought into contact with the facing tool to finish the ring-shaped grinding surface, tilting the polishing pad at a predetermined minute angle are relatively moved in the direction along the surface to be polished of the polishing target
The polishing method according to claim 6 to form a Jo polished surface. 8. A slidable contact area between the surface to be polished and the ring-shaped polishing surface is adjusted by adjusting an inclination angle of a rotation axis of the polishing pad with respect to the surface to be polished to be polished. The polishing method according to claim 6 . 9. A sliding contact area between the surface to be polished and the ring-shaped polishing surface is adjusted by adjusting a processing pressure of the ring-shaped polishing surface of the polishing pad with respect to the surface to be polished to be polished. The polishing method according to claim 6, which is adjusted. 10. Between the polishing pad and the object to be polished,
The polishing method according to claim 6 , wherein polishing is performed while supplying a polishing liquid that causes chemical mechanical polishing.