JP2001269855A - Polishing device and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing device and a polishing method capable of suppressing the excessive polishing of the outer peripheral end part of the polished face of a polished body such as a semiconductor wafer. SOLUTION: The polishing face 8a of a polishing tool 8 is brought into contact with the polished face of the wafer W so that a low-pressure region PL in the pressure distribution PR occurring at a contact part between the polishing face 8a and the polished face of the wafer W is located at the outer peripheral end part EG of the polished face and a high-pressure region PH is located on the inside of the polished face. After the polishing face 8a is brought into contact with the polished face, the polishing tool 8 is relatively moved in the radial direction of the wafer W for polishing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polishing apparatus and a polishing method.

[0002]

2. Description of the Related Art As semiconductor devices become more highly integrated and multi-layered, flattening of various interlayer insulating films or other films becomes more important in the process of manufacturing semiconductor devices. Various means have been proposed as a technique for planarization. In recent years, a CMP (Chemical Mechanical Polishing) method which applies a mirror polishing technique of a silicon wafer has attracted attention and is utilized. A method for flattening has been developed. FIG. 14 shows an example of a polishing apparatus using the CMP method. Polishing device 301 shown in FIG.
Has a main spindle 303 for rotating a cylindrical polishing tool 302 and a table 304 for holding a wafer W. The table 304 is rotatably mounted on a slider 306 provided movably in the X-axis direction along a rail 305, and is rotatably driven by a rotary drive unit including, for example, a motor, a pulley, a belt, and the like. Is done. The main spindle 303 is held movably in the Z-axis direction, and is positioned at a target position in the Z-axis direction by a drive mechanism (not shown). Polishing device 3 having the above configuration
In FIG. 01, first, the wafer W is rotated at a predetermined rotation speed, and a slurry as an abrasive obtained by mixing abrasive grains such as silicon oxide with a liquid such as an aqueous solution of potassium hydroxide is not shown on the wafer W. The slurry is supplied onto the wafer W from the slurry supply device. Next, the wafer W and the polishing tool 302 are rotated in the X-axis and Z-axis directions so that the polishing tool 302 is rotated at a predetermined number of revolutions, and the outer peripheral edge of the polishing tool 302 overlaps and comes into contact with the outer peripheral edge of the wafer W. Is positioned. The polishing tool 302 is positioned in the Z-axis direction so as to have a predetermined cutting amount with respect to the wafer W,
As a result, a predetermined processing pressure is generated between the polishing tool 302 and the wafer W. In this state, the wafer W is moved in the X-axis direction at a predetermined speed pattern, and the polishing tool 30 is moved.
While the wafer 2 is in contact with the wafer W, the wafer W is polished and the wafer W is flattened.

[0003]

By the way, the polishing tool 3
Reference numeral 02 denotes an elastic body formed of a ring-shaped member and formed of a resin such as polyurethane foam. The polishing tool 302 is pressed against the surface of the wafer W at a predetermined processing pressure. Therefore, the polishing tool 302 pressed against the wafer W is elastically deformed. As shown in FIG. 15, when the polishing tool 302 rotating in the direction of the arrow R1 moves in the processing progress direction D with respect to the wafer W rotating in the direction of the arrow R2 opposite to the arrow R1, the polishing tool 302 Circle A
The region indicated by runs over the wafer W from outside the wafer W. In this riding region, the polishing tool 302
For example, as shown in FIG.
The polishing surface 302a of the polishing tool 302 is elastically deformed because the polishing surface 302a of the polishing tool 302 rides on the surface of the wafer W from the outer peripheral edge EG of the wafer W, and the polishing just before the polishing surface 302a rides on the surface of the wafer W located near the outer peripheral edge EG. The surface 302a
The wafer W is projected downward from the surface of the wafer W.
When the polishing surface 302a of the polishing tool 302 is elastically deformed as described above, the portion of the polishing surface 302a protruding downward with respect to the surface of the wafer W comes into strong contact with the outer peripheral end portion EG of the wafer W, and the end portion due to stress concentration. As a result, the outer peripheral edge of the wafer W is damaged. On the other hand, in a region where the polishing tool 302 indicated by a circle B in FIG.
As shown in FIG. 16B, the polishing surface 3 of the polishing tool 302
02a is separated from the surface of the wafer W through the outer peripheral end EG, so that the polishing surface 3 of the polishing tool 302 elastically deformed.
02a is separated from the outer peripheral end EG of the wafer W, and the deformation is restored while the stress is relaxed. In this region, a pressure increase due to a hydrodynamic phenomenon also occurs. For this reason, in a region where the polishing tool 302 escapes from the inside of the wafer W to the outside of the wafer W, the outer peripheral edge of the wafer W is hardly damaged.

When damage to the outer peripheral edge EG of the wafer W due to the protruding portion of the polishing surface 302a as described above is accumulated, the wafer W is rotated.
As shown in FIG. 17, an excessively polished portion 352 that is excessively polished is formed over the entire outer peripheral portion of the wafer W. When the excessively polished portion 352 is formed, the number of semiconductor chips formed on one wafer W is reduced, and there is a disadvantage that the yield is reduced. Further, in a region where the polishing surface 302a of the polishing tool 302 rides on the outer peripheral edge EG of the wafer W, damage to the polishing surface 302a is large, and the quality of the polishing surface 302a is apt to be rapidly deteriorated.
Variations in processing conditions are likely to occur. In order to prevent the processing conditions from fluctuating, it is necessary to condition the polished surface 302a by means such as dressing.
If the frequency of conditioning to make the state of 2a appropriate is increased, there is also a disadvantage that productivity of the polishing apparatus is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide a polishing method capable of suppressing excessive polishing of the outer peripheral edge of a surface to be polished of a body to be polished such as a semiconductor wafer. An object of the present invention is to provide an apparatus and a polishing method.

[0006]

According to the present invention, there is provided a polishing method comprising the steps of: rotating a polishing surface of a rotating polishing tool whose rotation axis is inclined with respect to a direction perpendicular to a holding surface for holding an object to be polished; Relatively pressing against the surface to be polished of the body to bring the polishing surface into partial contact with the surface to be polished, moving the polishing tool and the object to be polished, and moving the contact portion within the surface to be polished A polishing method for processing the surface to be polished by causing the high pressure region at least in the pressure distribution having a high pressure region in the center and a low pressure region in the peripheral portion generated in the contact portion. The processing of the surface to be polished is performed while controlling the relative position between the polishing tool and the object to be polished so that the polishing tool always stays within the surface to be polished away from the outer peripheral end of the surface to be polished.

The outer peripheral edge of the surface to be polished is polished in a low pressure region of the contact portion.

In the pressure distribution generated at the contact portion between the polished surface and the surface to be polished, the low pressure region is located at the outer peripheral end of the surface to be polished, and the high pressure region is the polished surface. The polishing surface of the polishing tool is brought into contact with the surface to be polished of the object to be polished so as to be located inside the surface, and the polishing surface is brought into contact with the surface to be polished. Polishing is performed by relative movement in the radial direction of the polishing body.

The polishing tool is elastically deformed by contact with the object to be polished.

[0010] The contour of the pressure distribution generated at the contact portion is a crescent extending in a direction perpendicular to the traveling direction of the polishing tool.

In the crescent-shaped pressure distribution, the central part has the maximum pressure and the pressure decreases toward the peripheral part.

A polishing apparatus according to the present invention is characterized in that a polishing surface of a rotating polishing tool whose rotation axis is inclined with respect to a direction perpendicular to a holding surface for holding an object to be polished, By relatively pressing the polishing surface to partially contact the surface to be polished, moving the polishing tool and the object to be polished to move the contact portion within the surface to be polished, A polishing apparatus for processing a surface, wherein, of the pressure distribution having a high pressure region in a central portion generated in the contact portion and a low pressure region in a peripheral portion, at least the high pressure region is always a surface of the polished surface. Control means is provided for controlling a relative position between the polishing tool and the object to be polished so as to be contained in the surface to be polished away from the outer peripheral end.

In the present invention, when the polishing surface of the polishing tool is pressed against the surface to be polished of the object to be polished, the rotation axis of the polishing tool is inclined toward the traveling direction of the polishing tool. Partially contacts Due to the partial contact between the polished surface and the polished surface, the contact portion of the polished surface is elastically deformed, and pressure is generated at this contact portion. The pressure generated at the contact portion has a crescent-shaped pressure distribution having a high pressure region at the center and a low pressure region at the periphery. For example, when the polishing surface of the rotating polishing tool rides on the surface to be polished from the outside of the object to be polished, and the high pressure region of the contact portion of the polishing surface is on the outer peripheral end of the surface to be polished, the polishing surface is high The material is largely elastically deformed by the pressure, stress is concentrated on the outer peripheral edge of the polished surface, and the outer peripheral edge of the polished surface is excessively polished. For this reason,
In the present invention, the high pressure region of the contact portion between the polishing tool and the polishing surface is such that the high pressure region of the contact portion of the polishing surface always falls within the surface to be polished in a state away from the outer peripheral end of the surface to be polished. The apparatus position of the polishing tool and the object to be polished is controlled so as not to be located at the outer peripheral end of the surface to be polished.

In the present invention, instead of positioning the high-pressure region of the contact portion between the polishing tool and the polishing surface at the outer peripheral end of the surface to be polished, the low-pressure region of the contact portion of the polishing surface is positioned. The outer peripheral edge of the surface to be polished is polished by the pressure region.
Since the outer peripheral edge of the polished surface is polished by the low-pressure region of the contact portion of the polished surface, excessive polishing of the outer peripheral edge of the polished surface is suppressed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a polishing apparatus to which the present invention is applied. The polishing apparatus 1 shown in FIG. 1 includes a polishing tool 8, a spindle spindle 21 for rotating and holding the polishing tool 8, a Z-axis moving mechanism 11 for moving and positioning the spindle spindle 21 in the Z-axis direction, and a wafer W for holding and rotating. Holding table 41 to be held and X
An X-axis moving mechanism 51 for moving in the axial direction;
1 is provided.

The main spindle 21 holds the polishing tool 8, and rotates the polishing tool 8 about a rotation axis K1. The spindle 21 incorporates therein a spindle 23, a hydrostatic bearing for rotatably holding the spindle 23, and a servomotor for rotating the spindle 22. Also,
The main spindle 21 is held by a spindle holder 20. The spindle holder 20 is movably held on the column 3 by a guide (not shown) along the Z-axis direction. Further, a slurry / pure water supply nozzle 81 for supplying slurry as slurry and pure water onto the wafer W is provided at a predetermined position on the outer periphery of the main spindle 21.
Is provided.

The Z-axis moving mechanism 11 is provided along the Z-axis direction (vertical direction) on the portal column 3 erected on the base 2 so that the main spindle 21 can be moved in the Z-axis direction. keeping. The Z-axis moving mechanism 11 holds the polishing surface 8a of the polishing tool 8 in a direction facing the surface to be polished of the wafer W, and determines the relative position of the polishing surface 8a in the facing direction to the surface to be polished of the wafer W. Specifically, the Z-axis moving mechanism 11 includes a servo motor 12 fixed to the column 3.
And a screw shaft 13 formed with a screw connected to the servomotor 12, and a Z-axis slider 14 formed with a screw portion to be screwed with the screw shaft 13 and connected to the spindle holder 20. By driving the servo motor 12 to rotate, the Z-axis slider 14 moves up or down along the Z-axis direction, and the spindle holder 20 connected to the Z-axis slider 14 moves up or down along the Z-axis direction. Thus, by controlling the amount of rotation of the servomotor 12, the polishing tool 8 can be positioned in the Z-axis direction.

The holding table 41 is provided with a holding plate 41a provided in parallel with the horizontal direction for holding a wafer W as an object to be polished. The wafer W is held on the holding plate 41a by, for example, chucking means such as vacuum suction. Chucking by. Further, the holding table 41 includes, for example, a servomotor, and thereby rotates the wafer W.

The X-axis moving mechanism 51 includes a servo motor 55
And a screw shaft 54 formed with a screw connected to the servomotor 55, an X-axis slider 53 formed with a screw portion screwed to the screw shaft 54, and an X-axis slider 53 connected to the X-axis slider 53.
An X-axis table 52, which is movably held in the axial direction by a guide (not shown) and on which the above-described holding table 41 is installed, is provided. The X-axis moving mechanism 51 holds the holding table 41, and relatively moves the polishing tool 8 and the wafer W along the holding plate 41a of the holding table 41. That is, by driving the servo motor 55 to rotate, the X-axis slider 53 moves in any direction in the X-axis direction, and the X-axis table 52 also moves in any direction in the X-axis direction. Holding plate 4
1a moves in any direction along the horizontal plane in the X-axis direction.
It relatively moves along the first holding plate 41a.

The polishing tool 8 is a cylindrical member fixed to the lower end surface of the main shaft 22 and made of an elastic body which is elastically deformed when pressed against the wafer W. As a material for forming the polishing tool 8, for example, a resin such as foamable polyurethane or a material obtained by solidifying abrasive grains made of, for example, cerium oxide (CeO ₂ ) with a soft binder can be used. As the soft binder, for example, melamine resin,
A urethane resin or a phenol resin can be used. The polishing tool 8 basically has an annular end surface substantially parallel to a plane perpendicular to the rotation axis K1 on the lower end surface of the cylindrical member, and this is a polishing surface for processing the polished surface of the wafer W. 8a. The polishing surface 8a of the polishing tool 8 is faced in accordance with the inclination angle α of the rotation axis K of the polishing tool 8 described later, and is used in the state of a conical surface inclined at the same angle as the inclination angle α of the rotation axis K. You. The polishing tool 8 has a diameter of 8
When polishing an inch wafer, for example, a wafer having a diameter of 200 (mm) × a width of 20 (mm) × a thickness of 20 (mm) can be used. That is, the diameter of the wafer W and the outer diameter of the polishing tool 8 are substantially the same.

The control device 101 controls the driving of the servomotor 55 of the X-axis moving mechanism 51 to control the position and speed of the wafer W in the X-axis feed direction. Also, the control device 1
01 controls the drive of the servo motor 12 of the Z-axis moving mechanism 11 to control the position of the polishing tool 8 in the Z-axis direction. Also,
The control device 101 controls the drive of a servomotor that rotates the main shaft 22 to control the rotation of the polishing tool 8. Also,
The control device 101 drives and controls a servomotor that rotates the holding table 41 to control the rotation of the wafer W. The control device 101 controls the relative position between the polishing tool 8 and the wafer W by controlling the position and speed of the wafer W in the X-axis feed direction and the position of the polishing tool 8 in the Z-axis direction. A specific control method of the device 101 will be described later.

FIG. 2 is provided between the main spindle 21 and the spindle holder 20 of the polishing apparatus 1 having the above configuration.
FIG. 7 is a diagram for explaining a rotation axis tilting mechanism that adjusts a tilt amount of a rotation axis K1 of a spindle spindle 21 (polishing tool 8) with respect to an axis K2 perpendicular to a holding plate 41a of a holding table 41. In FIG. 2, a flange 24 is formed on the outer periphery of the spindle 21. The insertion shaft portion 27 above the flange portion 24 of the spindle spindle 21 is a parallel portion at a position close to the flange portion 24, and has a tapered surface tapering upward. The fitting hole 20b of the spindle holder 20 is fitted and inserted into the spindle holder 20. The rotating shaft tilting mechanism 61 is provided between the upper end surface 24 a of the flange 24 formed on the outer periphery of the main spindle 21 and the lower end surface 20 a of the spindle holder 20. The rotation axis tilting mechanism 61 includes, for example,
It is provided at three places located at equal intervals in the circumferential direction of the flange portion 24.

The upper end surface 24a of the flange portion 24 is a surface parallel to a plane perpendicular to the rotation axis K1 of the spindle spindle 21 (polishing tool 8). Further, the rotating shaft tilting mechanism 61 includes two tilt adjusting blocks 62 and 63. The tilt adjusting block 62 and the tilt adjusting block 63
By adjusting the relative positional relationship between the upper end surface 24a and the lower end surface 20a of the spindle holder 20, the distance between the upper end surface 24a of the flange portion 24 of the main spindle 21 and the lower end surface 20a of the spindle holder 20 can be adjusted. Therefore, by adjusting the rotation axis tilt mechanisms 61 provided at three locations, the tilt angle of the rotation axis K1 of the spindle spindle 21 (polishing tool 8) with respect to the axis K2 perpendicular to the holding plate 41a of the rotary table 41 can be set to any value. And can be inclined in any direction.

Next, a polishing method of the present invention using the above-described polishing apparatus 1 will be described. First, the rotation axis tilting mechanism 61 of the polishing apparatus 1 is adjusted so that the rotation axis K1 of the polishing tool 8 is oriented in the direction of travel of the polishing tool 8 with respect to a direction perpendicular to a plane parallel to the holding plate 41a of the turntable 41. To a predetermined angle. Specifically, as shown in FIG. 3, the rotation axis K1 of the polishing tool 8 is set with respect to an axis O perpendicular to a plane (XY plane) parallel to the holding plate 41a of the rotary table 41. It is inclined at an angle α toward a traveling direction D relative to the wafer W (a direction in which polishing proceeds). When the inclination angle α of the rotation axis K1 of the polishing tool 8 is 8 inches in diameter for the wafer W, for example,
The height difference Hα in the Z-axis direction at the front and rear ends of the polishing surface 8a of the polishing tool 8 shown in FIG. 3 in the X-axis direction is several μm to several hundred μm /.
It is set to a value of about 200 mm. That is, the inclination angle is about several μm to several hundred μm with respect to the length of 8 inches. The polishing tool 8 has a state in which the polishing surface 8a has been subjected to facing processing in advance along a horizontal plane in a state where the rotation axis K1 is inclined at the inclination angle α, and the polishing surface 8a is inclined at the same angle as the inclination angle α. Has become.

Next, in the polishing apparatus 1 in which the rotation axis K1 is inclined at the inclination angle α, the back surface of the wafer W is moved to the holding plate 41a of the rotation table 41 as shown in FIG.
The rotating table 41 and the polishing tool 8 are rotated. Note that the rotation direction R1 of the polishing tool 8 and the rotation direction R2 of the wafer W are reversed.

Further, a predetermined amount of the slurry SL is discharged from the slurry / pure water supply nozzle 81 onto the wafer W. It should be noted that the slurry SL is always replenished by a necessary amount even during polishing. The slurry is not particularly limited. For example, a slurry in which silica-based fumed silica and high-purity ceria are suspended in an aqueous solution based on potassium hydroxide is used for an oxide film, and an abrasive is polished in alumina for a wiring metal. A mixture obtained by mixing a solvent having an oxidizing power with a working fluid formed as abrasive grains can be used.

When the wafer W and the polishing surface 8a of the polishing tool 8 are separated from each other, as shown in FIG. 4, the polishing tool 8 is moved with respect to the wafer W in the Z-axis direction indicated by an arrow E1 and an arrow D.
Are relatively moved in the X-axis direction indicated by. When the polishing tool 8 is moved relative to the wafer W in the Z-axis direction indicated by an arrow E1 and the X-axis direction indicated by an arrow D, as shown in FIG. The polishing surfaces 8a of the tool 8 come into contact with each other in an overlapping state. At this time, since the polishing surface 8a of the polishing tool 8 is inclined at an angle α with respect to the surface of the wafer W, the polishing surface 8a is
Contact partially, but not entirely, with the surface. Further, the polishing tool 8 is pressed against the wafer W with a predetermined load F,
Pressure is generated at a contact portion PR between the polishing surface 8a of the polishing tool 8 and the surface to be polished of the wafer W.

The polishing surface 8a of the polishing tool 8 is elastically deformed by being pressed against the wafer W, and a pressure distribution PR is generated at a contact portion of the elastically deformed polishing surface 8a as shown in FIG. In FIG. 6, the pressure gradient is indicated by a contour line. Although the pressure distribution PR does not actually occur outside the wafer W, it is shown that the pressure distribution PR also exists on the polishing surface 8a outside the wafer W for convenience of explanation. The contour shape of the pressure distribution PR is a substantially crescent shape extending in a direction perpendicular to the traveling direction D of the polishing tool 8.

As shown in FIG. 6, for example, the pressure distribution PR has a high pressure region PH at the center and a low pressure region PL at the periphery, and the high pressure region PH has the maximum pressure and moves toward the periphery. The pressure drops. Therefore, there is a pressure gradient from the high pressure region PH to the low pressure region PL.

High pressure region P of pressure distribution PR on polished surface 8a
H has a relatively large processing amount per unit time because the pressure acting on the wafer W is high, and the low-pressure region PL has a relatively small processing amount because the pressure acting on the wafer W is low. Therefore, a region with a high processing efficiency and a region with a low processing efficiency exist in the pressure distribution PR.

In the polishing method according to this embodiment, the high pressure region PH generated on the polishing surface 8a of the polishing tool 8 is separated from the outer peripheral edge of the surface to be polished of the wafer W in the polishing surface of the wafer W. And the low pressure region PL is located at the outer peripheral end EG of the surface to be polished of the wafer W,
The polishing surface 8a of the polishing tool 8 is brought into contact with the surface to be polished of the wafer W. Thus, the processing of the predetermined region KR inward from the outer peripheral end EG of the wafer W is started.

Further, by bringing the polishing surface 8a of the polishing tool 8 into contact with the surface to be polished of the wafer W and pressing it with the load F as described above, the outer peripheral edge EG of the surface to be polished of the wafer W is formed.
Only a relatively low pressure acts from the polishing surface 8a.

On the other hand, for example, when the polishing surface 8a is brought into contact with a position outside the wafer W as compared with the case shown in FIG.
The high pressure region PH of R is located on the outer peripheral end EG of the surface to be polished of the wafer W or is located close to the outer peripheral end EG. For this reason, the outer peripheral edge E of the surface to be polished of the wafer W
High pressure acts on G from the polishing surface 8a.

For example, when the polishing surface 8a is brought into contact with the inner side of the wafer W as compared with the case shown in FIG. 6, the pressure distribution PR becomes farther from the outer peripheral portion EG of the wafer W as shown in FIG. , A non-processed region NR that is not processed is generated between the processed region KR due to the pressure distribution PR and the outer peripheral edge EG of the polished surface of the wafer W.

FIG. 9 shows a circle C in FIGS.
7 is a cross-sectional view showing a relationship between the polishing tool 8 and the wafer W in a region where the polishing surface 8a runs from the outside of the wafer W toward the outer peripheral end EG of the wafer W. FIG.
(A) shows the pressure distribution PR as described with reference to FIG.
3 shows a state in which the polished surface 8a and the polished surface of the wafer W are brought into contact with each other so that the low pressure region PL is located at the outer peripheral end EG of the wafer W. As can be seen from FIG. 9A, since the pressure of the polishing surface 8a acting on the outer peripheral end EG of the wafer W is relatively low, the amount of elastic deformation of the polishing surface 8a is also small.

FIG. 9B shows that the high pressure region PH of the pressure distribution PR is located on the outer peripheral end EG of the wafer W or approaches the outer peripheral end EG as described with reference to FIG. The state when the polished surface 8a and the polished surface of the wafer W are brought into contact with each other so as to be positioned is shown. FIG.
As can be seen from (b), since the pressure of the polishing surface 8a acting on the outer peripheral edge EG of the wafer W is relatively high, the polishing surface 8a
The elastic deformation of “a” also increases. When the amount of elastic deformation of the polished surface 8a is large, stress concentrates on the outer peripheral edge EG of the wafer W, and the outer peripheral edge EG of the wafer W is excessively polished.

FIG. 9 (c) shows the polished surface 8a and the polished surface of the wafer W such that the pressure distribution PR is located away from the outer peripheral end EG of the wafer W and inside as described with reference to FIG. Shows the state when the contact is made. FIG.
As can be seen from (c), no pressure acts on the outer peripheral edge EG of the wafer W from the polishing surface 8a, and therefore, the outer peripheral edge EG of the wafer W is not polished.

As described above, the pressure distribution PR on the polishing surface 8a
Is generated optimally in the surface to be polished of the wafer W, that is, in the X-axis direction and the Z direction between the polishing tool 8 and the wafer W so that excessive pressure does not act on the outer peripheral end EG of the wafer W.
By controlling the relative position in the axial direction optimally and bringing the polished surface 8a into contact with the polished surface of the wafer W, excessive polishing of the outer peripheral end EG of the wafer W can be suppressed.

Next, after bringing the polished surface 8a into contact with the surface to be polished of the wafer W, as shown in FIG. 10, when the wafer W is moved in the X-axis direction indicated by the arrow C, the pressure distribution PR of the polished surface 8a is reduced. Moves in the radial direction of the wafer W from the outer peripheral end EG of the wafer W. As a result, the surface to be polished of the wafer W is processed from the outer periphery toward the inside, and the wafer W
When the pressure distribution PR of the polished surface 8a reaches the center of the wafer W, the entire polished surface of the wafer W is processed. In this state,
Since the pressure distribution PR of the polished surface 8a exists inside the surface to be polished of the wafer W, excessive polishing of the outer peripheral end portion EG of the wafer W does not occur. Further, the processing amount of the polished surface of the wafer W can be arbitrarily adjusted by adjusting the feed speed of the wafer W, for example.

Further, when the wafer W is moved from the state shown in FIG. 10 in the X-axis direction indicated by the arrow C, the polished surface of the wafer W is processed again from the inside to the outer periphery.
As shown in (2), the outer peripheral end of the polishing tool 8 approaches the processing end point P2 on the outer peripheral edge of the wafer W. When the polishing surface 8a of the polishing tool 8 moves to a position overlapping the processing end point P2, the polishing tool 8 is raised in the Z-axis direction indicated by the arrow E2, and the polished surface of the wafer W and the polishing surface 8a of the polishing tool 8 are moved. Separate.

When the polishing surface of the wafer W is separated from the polishing surface 8a of the polishing tool 8, the polishing tool 8 and the wafer W
Are relative positions in the X-axis direction as shown in FIG. In FIG. 12, a pressure distribution P generated on the polishing surface 8a is shown.
The high pressure region PH of R does not reach the outer peripheral end EG of the wafer W, and the polishing tool 8 is separated from the wafer W at a position where the high pressure region PH is separated from the outer peripheral end EG. As described above, by separating the polishing tool 8 from the wafer W at a position where the high pressure region PH is separated from the outer peripheral end EG of the wafer W, excessive polishing of the outer peripheral end EG of the wafer W can be suppressed.

Here, FIG. 13 shows the amount of processing of the outer peripheral edge EG of the wafer W when polishing a film having a predetermined thickness formed on the wafer W using the polishing method according to the present embodiment. The measurement results are shown. The diameter of the wafer W is 20
0 mm, and the position 100 mm from the center of the wafer W is the outer peripheral end. In FIG. 13, the film thickness distribution indicated by (1) indicates that the outer peripheral edge of the polishing tool 8 is the outer peripheral edge E of the wafer W.
This is a case where the contact is made at a position of 40 mm in the radial direction from G (at a position of 60 mm from the center of the wafer W). Also,
The film thickness distribution shown by (2) is a case where the outer peripheral end of the polishing tool 8 is brought into contact with the outer peripheral end EG of the wafer W at a position 5 mm radially (at a position 95 mm from the center of the wafer W).

As can be seen from FIG. 13, in the film thickness distribution indicated by (1), the film thickness at the outer peripheral edge EG is substantially constant, and no excessive polishing occurs. On the other hand, in the film thickness distribution shown in (2), the film thickness at the outer peripheral end portion EG is small, and the outer peripheral end portion EG
Excessive polishing occurs. From this, the polishing tool 8
It can be seen that by appropriately adjusting the position at which the polishing surface 8a of the wafer W comes into contact with the surface to be polished of the wafer W, excessive polishing at the outer peripheral end EG can be suppressed.

In order to determine the contact position between the polishing surface 8a of the polishing tool 8 and the surface to be polished of the wafer W, for example, the processing is performed by changing the contact position between the polishing surface 8a and the surface to be polished of the wafer W. Measuring the processing amount of the surface to be polished of the wafer W at each contact position, and preventing excessive polishing at the outer peripheral end portion EG;
Alternatively, it can be determined by obtaining the contact position where the excessive polishing is most suppressed.

As described above, according to the present embodiment, by optimizing the contact position between the polishing surface 8a of the polishing tool 8 and the surface to be polished of the wafer W, the outer peripheral edge EG of the wafer W
It is possible to suppress excessive polishing that occurs during the polishing. Therefore, according to the present embodiment, the polishing surface 8a of the polishing tool 8
The polishing apparatus 1 does not require any additional function or mechanism other than optimizing the contact position between the wafer and the surface to be polished of the wafer W.
Processing performance can be dramatically improved. Also,
According to the present embodiment, since the outer peripheral edge EG of the wafer W is processed by the low pressure region PL generated on the polishing surface 8a of the polishing tool 8, the polishing surface 8a is formed in the riding region where the polishing surface 8a runs on the wafer W. Large elastic deformation does not occur, and abrasion of the polishing surface 8a can be suppressed.

The present invention is not limited to the above embodiment. In the embodiment described above, the rotating wafer W
And the rotating polishing tool 8 are moved in phase with each other in the X-axis direction.
The case where the polished surface of the wafer W is entirely processed has been described. In the partial polishing method in which the polished surface of the wafer W is partially brought into contact with the polished surface 8a of the polishing tool 8, the polished surface is processed in a certain direction (X-axis direction). Instead of the relative movement, the contact portion between the surface to be polished of the wafer W and the polishing surface 8a of the polishing tool 8 can be arbitrarily scanned and processed by the relative movement in the other direction. It is possible. At this time, the contact portion between the polished surface of the wafer W and the polished surface 8a of the polishing tool 8 moves to an arbitrary position in the polished surface of the wafer W. May move to. In the case where the contact portion moves to the EG near the outer peripheral end of the wafer W, the high pressure region PH of the pressure distribution PR generated at the contact portion is always located on the surface to be polished without being located on the EG near the outer peripheral end. By processing the EG near the outer peripheral end in the low pressure region PL, excessive polishing of the outer peripheral end EG can be suppressed.

[0047]

According to the present invention, excessive polishing of the outer peripheral edge of the surface to be polished of the object to be polished can be suppressed. Further, according to the present invention, it is possible to suppress wear of the polishing tool,
As a result, the cost required for polishing can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a polishing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a configuration of a rotating shaft tilting mechanism.

FIG. 3 is a view for explaining a state immediately before the polishing process of the polishing apparatus 1 is started.

FIG. 4 is a cross-sectional view for explaining an operation when the polishing tool 8 is brought into contact with a wafer W.

FIG. 5 is a plan view showing a state in which a polishing tool 8 is brought into contact with a wafer W.

FIG. 6 is a diagram showing an example of a pressure distribution PR generated by contact between the polishing surface 8a and the surface to be polished of the wafer W.

FIG. 7 is a diagram showing another example of the pressure distribution PR generated by the contact between the polishing surface 8a and the surface to be polished of the wafer W.

FIG. 8 is a diagram showing still another example of a pressure distribution PR generated by the contact between the polishing surface 8a and the surface to be polished of the wafer W.

FIG. 9 is a cross-sectional view showing each state of the polishing tool 8 in a riding area in the states of FIGS. 6 to 8;

FIG. 10 is a view showing a state in which a contact portion has moved and polishing of a wafer W has progressed.

FIG. 11 is a diagram showing a state when a wafer W and a polishing tool 8 are separated from each other.

FIG. 12 is a view for explaining a relative position between the wafer W and the polishing tool 8 for separating the wafer W from the polishing tool 8;

FIG. 13 is a graph showing the remaining film thickness distribution at the outer peripheral edge of the wafer W when the wafer W is actually processed by the polishing method of the present invention.

FIG. 14 is a diagram illustrating an example of a polishing apparatus using a CMP method.

FIG. 15 is a plan view showing a relative positional relationship between a polishing tool 302 and a wafer W.

FIG. 16 is a cross-sectional view showing elastic deformation at the outer peripheral edge of the wafer caused by pressing the polishing surface of the polishing tool against the wafer.

FIG. 17 is a plan view showing a state in which the outer peripheral edge of the wafer W is excessively polished due to elastic deformation of the polishing surface of the polishing tool.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Polishing apparatus, 8 ... Polishing tool, 8a ... Polishing surface, 101 ...
Control device, W: wafer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Osamu Morikawa, Inventor 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Tokuhisa Kawamura 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 3C058 AA07 AA11 BA02 BA05 BA07 BB03 BC02 CB01 DA12 DA17

Claims (16)

[Claims] A polishing surface of a rotating polishing tool whose rotation axis is inclined with respect to a direction perpendicular to a holding surface for holding an object to be polished,
The rotating surface of the object to be polished is pressed relatively to the surface to be polished to bring the polishing surface into partial contact with the surface to be polished, and the polishing tool and the object to be polished are moved to bring the contact portion into contact with the object to be polished. A polishing method for processing the surface to be polished by moving within a polishing surface, wherein at least a pressure distribution having a high pressure region in a central portion generated in the contact portion and a low pressure region in a peripheral portion. The high pressure region is always kept away from the outer peripheral end of the surface to be polished so as to fit within the surface to be polished, so that the relative position between the polishing tool and the object to be polished is controlled while controlling the relative position of the surface to be polished. Polishing method for processing. 2. The polishing method according to claim 1, wherein the outer peripheral edge of the surface to be polished is polished in a low pressure region of the contact portion. 3. A pressure distribution generated at a contact portion between the polishing surface and the surface to be polished, wherein the low pressure region is located at an outer peripheral end of the surface to be polished, and the high pressure region is The polishing surface of the polishing tool is brought into contact with the surface to be polished so that the polishing tool is located inside the surface to be polished. The polishing method according to claim 1, wherein the polishing is performed by relatively moving the object to be polished in a radial direction. 4. The polishing method according to claim 1, wherein the polishing tool is elastically deformed by being pressed against the object to be polished. 5. The polishing method according to claim 4, wherein the contour shape of the pressure distribution generated in said contact portion is a crescent extending in a direction perpendicular to the direction in which said polishing tool advances. 6. The crescent-shaped pressure distribution has a maximum pressure at a central portion and decreases in pressure toward a peripheral portion.
3. The polishing method according to 1. 7. The polishing method according to claim 1, wherein a rotation axis of the polishing tool is inclined at a predetermined angle in a direction in which the polishing tool advances with respect to the object to be polished. 8. The polishing method according to claim 7, wherein the polishing surface of the polishing tool is a conical surface inclined at the same angle as the inclination angle of the rotating shaft. 9. A polishing surface of a rotating polishing tool whose rotation axis is inclined with respect to a direction perpendicular to a holding surface for holding an object to be polished,
The rotating surface of the object to be polished is pressed relatively to the surface to be polished to bring the polishing surface into partial contact with the surface to be polished, and the polishing tool and the object to be polished are moved to bring the contact portion into contact with the object. A polishing apparatus for processing the surface to be polished by moving within a polishing surface, wherein at least a pressure distribution having a high pressure region in a central portion generated in the contact portion and a low pressure region in a peripheral portion. A polishing apparatus comprising control means for controlling a relative position between the polishing tool and the object to be polished so that the high-pressure region always falls within the surface to be polished while being separated from an outer peripheral end of the surface to be polished; . 10. The polishing apparatus according to claim 9, wherein said control means causes the outer peripheral edge of said polished surface to be polished in a region where the pressure distribution at the contact portion of said polishing tool is relatively low. 11. The control means according to claim 1, wherein, of the pressure distribution generated at a contact portion between the polishing surface and the surface to be polished, the low pressure region is located at an outer peripheral end of the surface to be polished, and After the polishing surface of the polishing tool is brought into contact with the surface to be polished of the object to be polished so that the high pressure region is located inside the surface to be polished, and after the polishing surface and the surface to be polished are brought into contact with each other. ,
The polishing apparatus according to claim 9, wherein the polishing tool is relatively moved in a radial direction of the object to be polished. 12. The polishing apparatus according to claim 9, wherein said polishing tool is an elastic body which is elastically deformed by being pressed against said object to be polished. 13. The polishing apparatus according to claim 12, wherein the contour of the pressure distribution generated in said contact portion is a crescent extending in a direction perpendicular to the direction of travel of said polishing tool. 14. The polishing apparatus according to claim 13, wherein the crescent-shaped pressure distribution has a maximum pressure at a central portion and a pressure decreases toward a peripheral portion. 15. The polishing apparatus according to claim 9, wherein a rotation axis of the polishing tool is inclined at a predetermined angle in a direction in which the polishing tool advances with respect to the object to be polished. 16. A polishing surface of the polishing tool comprises a conical surface inclined at the same angle as the inclination angle of the rotating shaft.
6. The polishing apparatus according to 5.