JPH071328A - Polishing device and method - Google Patents

Abstract

PURPOSE:To accurately flatten the surface of a workpiece to be polished without producing unusual points in the polished workpiece without severe cleaning of the lower surface of a top ring and without intervening a soft member such as mat between the lower surface of the top ring and the workpiece to be polished. CONSTITUTION:A polishing device is provided with a turn table driving device to rotate a turn table 20, a top ring driving device to rotate a top ring 3, and a lock ring 5 to lock the workpiece to be polished, which is arranged in the lower face of the top ring 3. The top ring's lower face being in contact with the workpiece is formed smooth, and the bore of the lock ring 5 is formed larger than the outer diameter of the workpiece to be polished so that the outer peripheral surface of the workpiece comes in contact with the inner peripheral surface of the lock ring 5 due to the rotation of the turn table 20, and the lock ring 5 gives torque to the workpiece due to the rotation of the top ring 3, resulting in the sun-and-planet motion of the workpiece.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus and method, and more particularly to a polishing apparatus and method for polishing a surface of a polishing object such as a semiconductor wafer to a flat and mirror surface with a polishing cloth.

[0002]

2. Description of the Related Art In recent years, as the degree of integration of semiconductor devices has increased, circuit wiring has become finer and the distance between wirings has become smaller. In particular, in the case of optical lithography of 0.5 μm or less, the depth of focus becomes shallow, so that the flatness of the image plane of the stepper is required. Therefore, it is necessary to flatten the surface of the semiconductor wafer. As one means of this flattening method, polishing is performed by a polishing device.

Conventionally, this type of polishing apparatus has a turntable and a top ring, and the top ring applies a constant pressure to the turntable, and an object to be polished is interposed between the turntable and the top ring. The surface of the object is flat and polished to a mirror surface. Normally, the object to be polished is polished on the lower surface of the top ring in a state of being fixed by wax adhesion, matting, vacuum suction or the like.

[0004]

However, in the conventional polishing apparatus described above, since the polishing object is fixed to the top ring surface, the polishing surface of the top ring object is affected by the dust adhering to the top ring surface. On the polishing surface of the object to be polished due to the influence of dust, which may cause overpolishing and uneven polishing. Therefore, in order to avoid this singularity, the top ring should be thoroughly washed to completely remove dust, or a soft member such as wax or mat should be interposed between the bottom surface of the top ring and the object to be polished. The convex part due to is not generated.

However, not only is it difficult to completely remove dust by the former cleaning method, but it is also very difficult to judge whether dust has been completely removed. In addition, it takes a long time to bond an object to be polished with wax. Further, the method of interposing a soft member between the top ring surface and the object to be polished also has a big problem in durability of the soft member.

The present invention has been made in view of the above circumstances, and polishes an object to be polished without thorough cleaning of the lower surface of the top ring and a soft member such as a mat between the lower surface of the top ring and the object to be polished. It is an object of the present invention to provide a polishing apparatus and method capable of achieving highly accurate flat and mirror-finished surface without generation of singular points.

[0007]

In order to achieve the above-mentioned object, a polishing apparatus of the present invention comprises a turntable having a polishing cloth on its upper surface and a top ring, and a space between the turntable and the top ring. A polishing apparatus for polishing a surface of a polishing object to be flat and mirror-finished by interposing a polishing object on the turntable driving apparatus for rotationally driving the turntable and a top ring driving apparatus for rotationally driving the top ring. And a retaining ring for the polishing object provided on the lower surface of the top ring, the bottom surface of the top ring that contacts the polishing object is formed smoothly, and the inner diameter of the retaining ring is set to the outside of the polishing object. It is made larger than the diameter by a predetermined amount, and is rotated by rotating the turntable. The outer peripheral surface of the object contacts the inner peripheral surface of the retaining ring, and the rotation of the top ring causes the retaining ring to impart a rotational force to the polishing object to cause the polishing object to make a planetary motion. It is characterized by.

Further, the polishing method of the present invention has a turntable having a polishing cloth stretched on the upper surface and a top ring, and the polishing object is interposed between the turntable and the top ring. In a polishing method for polishing the surface of the surface to be flat and mirror-finished, a step of rotating the turntable, a step of pressing a polishing object to the polishing cloth through the top ring, and a step of rotating the top ring, Due to the rotation of the turntable, the outer peripheral surface of the polishing object comes into contact with the inner peripheral surface of the retaining ring which is provided on the lower surface of the top ring and forms a predetermined amount of gap with the polishing object. The rotation of the retaining ring imparts a rotational force to the polishing target to It is characterized in that comprises the step of planetary motion in single object.

[0009]

According to the present invention having the above-mentioned structure, the object to be polished does not move synchronously with the top ring at the time of polishing and makes a predetermined planetary motion in the retaining ring, so that it adheres to the top ring surface. The influence of dust is leveled, that is, the portion that is over-polished due to the influence of dust is constantly moved, so the influence of dust is averaged and the polished surface of the polishing target is highly accurately flat and mirror-finished. .

The above points will be described in more detail. When dust adheres to the top ring surface, the dust S adhered to the lower surface of the top ring 3 is interposed between the top ring 3 and the semiconductor wafer 6 as shown in FIG. , The semiconductor wafer 6 is pushed up, and a convex portion having a slight height is generated on the surface of the semiconductor wafer 6 (in FIG. 6, the height of the convex portion is shown large for convenience of description), and the convex portion is a turntable during polishing. Friction with the polishing cloth 23 on 20 causes overpolishing. This over-polished portion appears as singular points 6a and 6a on the surface of the semiconductor wafer 6 as shown in FIG.

However, in the present invention, the polishing object is caused to make a planetary motion in the retaining ring, so that the convex portion which is over-polished due to the influence of dust always moves without staying at one point of the semiconductor wafer 6. ,
The influence of dust is averaged over the entire surface of the semiconductor wafer, no singular point appears, and the polished surface of the polishing object is highly accurately flat and mirror-finished.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a polishing apparatus and method according to the present invention will be described below with reference to the drawings. 1 and 2
FIG. 1 is a view showing a polishing portion of a semiconductor wafer polishing apparatus of the present invention, FIG. 1 is a vertical sectional view, and FIG. 2 is a plan view. The top ring portion of the polishing device is composed of a top ring drive shaft 1, a top ring 3, and a ball bearing 2 interposed between the top ring drive shaft 1 and the top ring 3.

At the center of the lower end surface of the top ring drive shaft 1, a concave spherical surface 1a with which a ball bearing 2 is in sliding contact is formed. Top ring 3 is the top ring body top 3-1
And the top ring body lower part 3-2. A concave spherical surface 3-1a with which the ball bearing 2 is in sliding contact is formed in the center of the upper surface of the top ring main body upper portion 3-1, and a wafer retaining ring 5 is attached to the outer peripheral portion of the top ring main body lower portion 3-2. .

A number of vacuum suction holes 3-2a are formed in the lower surface of the top ring main body 3-2 and open to the lower surface. A vacuum groove 3-1b communicating with the vacuum suction hole 3-2a is formed in the top ring body upper portion 3-1.
1b communicates with four vacuum holes 3-1c formed in the top ring body upper portion 3-1. The vacuum hole 3-1c is communicated with the vacuum line tube 10, the tube joint 9 and the tube joint 11 to the vacuum hole 1b provided at the center of the top ring drive shaft 1.

The top ring drive shaft 1 is integrally provided with a flange portion 1c, and four torque transmission pins 7 are provided on the outer periphery of the flange portion 1c. Further, four torque transmission pins 8 are provided on the upper surface of the top ring main body upper portion 3-1 of the top ring 3 corresponding to the torque transmission pins 7.
Is provided. The semiconductor wafer 6 is housed in a space surrounded by the lower surface of the lower portion 3-2 of the top ring main body, the inner circumference of the wafer detachment prevention ring 5 and the upper surface of the turntable (not shown), and the turntable is rotated and the top ring is rotated. The semiconductor wafer 6 is rotated while rotating the drive shaft 1 and transmitting the rotational torque to the top ring 3 by the engagement of the torque transmission pin 7 and the torque transmission pin 8 to rotate the top ring 3 and slide the top ring 3. The surface of is polished flat and mirror-finished.

A top ring holder 4 is provided above the flange portion 1c of the top ring drive shaft 1, and the top ring holder 4 is connected to the top ring 3 by bolts 41. A spring 42 is interposed between the bolt 41 and the top ring holder 4. When the top ring drive shaft 1 is raised, the top ring holder 4 rises together with the top ring 3. In this raised state, the spring 42 is soft and has a function of keeping the top ring 3 horizontal. The function of keeping the top ring 3 soft and horizontal works effectively when the semiconductor wafer 6 is transferred.

FIG. 3 is a diagram showing the overall construction of a polishing apparatus using the polishing section shown in FIGS. 1 and 2.
In FIG. 3, reference numeral 20 is a turntable, and the turntable 20 can rotate about a shaft 21. A turntable ring 22 is provided on the outer peripheral portion of the turntable 20 to prevent the polishing abrasive liquid and the like from scattering. Further, the polishing cloth 2 is provided on the upper surface of the turntable 20.
3 is stretched.

On the upper part of the turntable 20, the top ring portion having the above-mentioned structure is arranged. A top ring cylinder 12 is provided above the top ring drive shaft 1, and the top ring 3 is pressed against the turntable 20 by the top ring cylinder 12 with a constant pressure. Reference numeral 13 is a top ring drive motor, which applies rotational torque to the top ring drive shaft 1 via the gear 14, the gear 15, and the gear 16. A polishing abrasive liquid nozzle 17 is installed above the turntable 20 so that the polishing abrasive liquid Q can be sprayed onto the polishing cloth 23 of the turntable 20 by the polishing abrasive liquid nozzle 17.

Next, a polishing method using the polishing apparatus having the above structure will be described. A case of polishing a semiconductor wafer in which an insulating film made of silicon dioxide is formed on a silicon substrate will be described. First, the semiconductor wafer 6 is vacuum-sucked on the lower surface of the lower portion 3-2 of the top ring body. When the semiconductor wafer 6 is attracted to the lower surface of the lower polishing body lower portion 3-2, the vacuum hole 1b provided in the central portion of the top ring drive shaft 1 is connected to a vacuum source, thereby lowering the lower portion 3-2 of the top ring main body. Air is sucked from the vacuum suction hole 3-2a. In this state, the semiconductor wafer 6 placed on the delivery section (not shown) installed adjacent to the turntable 20 is vacuum-sucked by the lower surface of the top ring 3.

Next, after the top ring 3 holding the semiconductor wafer 6 is moved onto the turntable 20, the top ring 3 is lowered and the polishing cloth 23 on the upper surface of the turntable 20 is moved.
Position the semiconductor wafer 6 on top. And the vacuum hole 1b
And the vacuum source are disconnected, and the atmosphere is introduced into the vacuum suction hole 3-2a. Therefore, the semiconductor wafer 6 is the top ring 3
The semiconductor wafer 6 is released from the lower surface of the
It can be rotated with respect to the underside of. And
Operate the top ring cylinder 12 to move the top ring 3
The semiconductor wafer 6 by pushing toward the turntable 20.
Is pressed against the polishing cloth 23 on the upper surface of the turntable 20. At this time, the turntable 20 is rotating and the polishing abrasive liquid Q is held on the polishing cloth 23 by flowing the polishing abrasive liquid Q from the polishing abrasive liquid nozzle 17 onto the polishing cloth 23, and the semiconductor wafer 6 is polished. Polishing abrasive liquid Q enters the surface (lower surface) and polishing starts.

At this time, even if the upper surface of the turntable 20 is slightly tilted, the top ring 3 is swung quickly with respect to the top ring drive shaft 1 by the ball bearing 2. Even if the top ring 3 is tilted, the torque transmission pin 7 on the top ring drive shaft 1 side and the torque transmission pin 8 on the top ring 3 side are point-contacted, so that the contact points are shifted in each case and the top ring drive shaft 1 The rotation torque is reliably transmitted to the top ring 3.

After the polishing is completed, the semiconductor wafer 6 is again vacuum-sucked on the lower surface of the top ring 3, and the top ring 3 is moved from above the turntable 20 to carry the semiconductor wafer 6 to the next step such as a cleaning step.

As shown in FIG. 4, the semiconductor wafer 6 is not adsorbed and fixed on the lower surface of the top ring 3 as described above, and the diameter D _{2 of the} semiconductor wafer 6 and the retaining ring 5 are fixed.
Since there is a difference of D ₁ −D ₂ = d between the inner diameters D ₁ of
A certain point on the semiconductor wafer 6 contacts the stopper ring 5 at a point A. Since the top ring 3 and the retaining ring 5 are rotating, a force F is applied to the outer peripheral surface of the semiconductor wafer 6.

The bottom surface of the top ring 3 is made sufficiently smooth, and the bottom surface of the top ring 3 and the semiconductor wafer 6 are brought into direct contact with each other without placing a mat or the like, and the retaining ring attached to the top ring 3 as described above. By making the inner diameter D ₁ of the semiconductor wafer 5 larger than the outer diameter D ₂ of the semiconductor wafer 6 by a predetermined amount d, the semiconductor wafer 6 is caused to make a planetary motion with respect to the top ring 3 in the retaining ring 5, and thereby the top ring 3 It is possible to prevent the occurrence of a singular point on the polished surface that occurs when dust or the like exists between the lower surface and the semiconductor wafer 6.

The planetary movement means the movement of the semiconductor wafer 6 around the center of the top ring 3 relative to the top ring 3 while the semiconductor wafer 6 rotates about its own axis. The semiconductor wafer 6 performs the planetary motion when the following two conditions are satisfied.

Condition 1: The frictional force between the lower surface of the top ring 3 and the semiconductor wafer 6 is smaller than the frictional force between the polishing cloth 23 on the turntable 20 and the semiconductor wafer 6. In other words, as the force in the axial direction of the top ring drive shaft 1, the force applied from the top ring 3 to the semiconductor wafer 6 and the force applied from the turntable 20 to the semiconductor wafer 6 are equal, so the lower surface of the top ring 3 is The coefficient of friction between the semiconductor wafer 6 and the semiconductor wafer 6 is smaller than the coefficient of friction between the polishing pad 23 and the semiconductor wafer 6. The above-mentioned "to make the lower surface of the top ring 3 sufficiently smooth" means this. If this condition is not satisfied and the frictional force between the lower surface of the top ring 3 and the semiconductor wafer 6 is equal to or greater than the frictional force between the polishing pad 23 and the semiconductor wafer 6, the semiconductor wafer 6 is not connected to the top ring 3. Since they move as a unit, the planetary motion here cannot be obtained.

Condition 2: The inside diameter D ₁ of the retaining ring 5 attached to the top ring 3 is larger than the outside diameter D ₂ of the semiconductor wafer 6 by a predetermined amount (d). When the above condition 1 is satisfied, the force applied from the turntable 20 to the semiconductor wafer 6 is in a constant direction, so that the semiconductor wafer 6 has one point on the inner circumference of the retaining ring 5 (point A in FIG. 4). Touch to rotate. The fact that the inner diameter of the retaining ring 5 is larger than the outer diameter of the semiconductor wafer 6 as described above means that the semiconductor wafer 6
Means that the inner peripheral length of the retaining ring 5 is longer than the outer peripheral length of the top ring 3, that is, the retaining ring 5 is 1
During the circumference, the outer circumference of the semiconductor wafer 6 is contacted (see A in FIG. 4).
Point) and rotate more than one lap. That is, the semiconductor wafer 6 makes one rotation or more during one rotation of the top ring 3.
As a result, the semiconductor wafer 6 revolves around the center of the top ring 3, that is, revolves around the top ring 3.

The rotation of the semiconductor wafer 6 itself is due to the force F applied from the retaining ring 5 at the contact point (point A). Also,
Specifically, the inner diameter of the retaining ring-the outer diameter of the semiconductor wafer = 0.5 to
Top ring 3 that is 3.0 mm and from the start of polishing to the end of polishing
The effective polishing result can be obtained when the difference between the total number of rotations (total rotation angle) and the total number of rotations (total rotation angle) of the semiconductor wafer 6 is one rotation (360 °) or more. This is because if there is a gap of 0.5 mm, the planetary motion of the semiconductor wafer can be secured,
If a gap of 3 mm or more is provided, the turntable 20
This is because the rotation of the semiconductor wafer 6 may push it in the negative direction and cause the semiconductor wafer 6 to come into contact with the detachment prevention ring 5 by being impacted or broken. If the difference in total number of rotations (difference in total rotation angle) is one rotation (360 °) or more, the influence of dust is averaged over the entire surface of the semiconductor wafer. By performing the planetary motion shown in the present invention, when dust or the like exists between the lower surface of the top ring 3 and the semiconductor wafer 6, the position of the dust with respect to the semiconductor wafer 6 changes, and the dust pushes the semiconductor wafer 6. The points, that is, the points that become over-polished, are leveled, and the occurrence of singular points can be prevented.

FIG. 5 is a view for explaining the theory of rotation of the semiconductor wafer 6. The rotation of the turntable 20 pushes the semiconductor wafer 6 in the X direction, so that one of the inner circumferences of the retaining ring 5 (point A). While being pressed against the semiconductor wafer 6, the semiconductor wafer 6 rolls along the rotation of the retaining ring 5 without slipping. That is, the semiconductor wafer 6 rolls as shown in (a) → (b) → (c) of FIG. 5, a thick arrow indicates a predetermined point (point B) on the retaining ring 5, and a thin arrow indicates a predetermined point (point C) on the semiconductor wafer 6.

The gap between the semiconductor wafer 6 and the retaining ring 5 is d (mm), the diameter D (mm) and the peripheral length πD (m).
When the semiconductor wafer 6 of (m) is used, the inner peripheral length of the retaining ring 5 is (D + d) π (mm), and therefore the semiconductor wafer 6 is (D + d) π−πD = 1 rotation of the retaining ring 5. Leading to the retaining ring 5 by πd (mm) (Fig. 5 (c))
reference). When this is converted into an angle, (πd / πD) × 360 ° = (d / D) × 360 ° Here, when the rotation speed of the top ring 3 is r (rpm) and the polishing time is t (sec), it is t seconds. Rear top ring 3
And the total rotation angle of the semiconductor wafer 6 is (d / D) × 360 ° × (r / 60) × t = 6 (d / D) · r · t ° (1) Therefore, the top ring 3 and the semiconductor The condition for the difference in the total rotation angle of the wafer 6 to be 360 ° or more is: 6 (d / D) · r · t ° ≧ 360 °, that is, (d / D) · r · t ≧ 60 (2 )

That is, a good polishing result can be obtained by appropriately selecting the rotation speed r and the polishing time t so that (d / D) · r · t ≧ 60. For example, D = 150 mm
When (6 inches), d = 2 mm, and r = 100 (rpm), t ≧ 45 (sec) is obtained from the equation (2), and 45
If the polishing is performed for a second or more, a difference in total rotation angle between the top ring and the semiconductor wafer of 360 ° or more can be obtained, and a good polishing result can be obtained.

For example, D = 200 mm (8 inches), d
= 2 mm and r = 100 (rpm), t ≧ 60 (sec) from the equation (2), and 3 if polishing for 60 seconds or more.
A difference in total rotation angle between the top ring and the semiconductor wafer of 60 ° or more can be obtained, and good polishing results can be obtained.

The present inventors attempted the following experiment in order to confirm the rotation of the semiconductor wafer 6 in the retaining ring 5, that is, the planetary motion. As shown in FIGS. 9A and 9B, a semiconductor wafer having a silicon dioxide (SiO ₂ ) film formed thereon is used as the semiconductor wafer 6, and a flag made of a metal foil (thickness 0.01 mm) is provided on the edge of the semiconductor wafer 6. Glue 31 and
As shown in (c), the semiconductor wafer 6 to which the flag 31 is adhered is interposed between the top ring 3 and the polishing cloth 23 so that the flag 31 is outside the top ring 3, and the polishing cloth 2
3 (turntable) and the top ring 3 were rotated, and the difference in the total rotation angle between the top ring 3 and the semiconductor wafer 6 was observed. The experimental results are shown in Table 1.

[0034]

[Table 1]

In Table 1, the actual value of the difference in total rotation angle is the value measured from the movement of the flag 31, and the theoretical value of the difference in total rotation angle is the value obtained by the calculation of the above equation (1). . In addition, in Table 1, the polishing cloth 23 is coated with a resin sheet (Suba80).
0) shows the result of polishing for 45 seconds at a surface pressure of 300 g / cm ² using a solution in which 1% by weight of abrasive grains CeO ₂ was mixed in the polishing liquid.

FIG. 10 is a view showing the structure of the top ring used in the above experiment. FIG. 10 (a) shows a top ring A, FIG. 10 (b) shows a top ring B, and FIG. 10 (c) shows a top ring C.
Are shown respectively. For the top ring A, the top ring 3 is made of an alumina ceramic material and the retaining ring 5 is made of a vinyl chloride resin material. The top ring 3 is provided with 53 vacuum holes 3c, and the bottom surface is lapped to a mirror surface. There is. Top ring B is the bottom of the top ring body 3
-2 is made of an alumina ceramic material and the retaining ring 5 is made of a vinyl chloride resin material, 233 vacuum holes 3-2a are provided in the top ring 3, and the lower surface is finished to a mirror surface by lapping. The top ring C uses an alumina-based porous ceramic material having an average pore diameter of 85 μm in the 3-2′a portion of the lower portion 3-2 ′ of the top ring body. As shown in the experimental results, almost expected planetary motion is obtained in the top ring A, but the top ring B has many vacuum holes, and the top ring C has a porous lower surface. In addition, sufficient smoothness could not be obtained, the expected planetary motion could not be obtained,
A singular point has occurred.

In the above experiment, the retaining ring is
Although it is made of vinyl chloride resin having a large friction coefficient with the semiconductor wafer 6, a material having the same hardness (HRB50 to 150 in Rockwell hardness) as the resin, for example,
It is also possible to manufacture it from ABS resin (acrylonitrile / butadiene / styrene resin), PC resin (polycarbonate), polyethylene resin or the like. Retaining ring 5
Has an inner diameter of 0.5 to 3.0 relative to the outer diameter of the semiconductor wafer 6.
Good results were obtained by increasing the size by mm. Further, the retaining ring can be made of a metal core material and a resin material covering the core material. In this case, the resin material can secure a large friction coefficient with the semiconductor wafer, and the core material can secure the rigidity.

As shown in Table 1, when the semiconductor wafer 6 is not vacuum-adsorbed on the lower surface of the top ring, it can be confirmed that the semiconductor wafer 6 makes a planetary motion in the retaining ring 5. In this way, when the semiconductor wafer 6 makes a planetary motion in the retaining ring 5, no singular point appears on the polished surface.
Particularly good results are obtained when the difference between the total rotation angles of the top ring 3 and the semiconductor wafer 6 is 360 ° or more.

The reason why no singular point appears on the polished surface when the semiconductor wafer 6 makes a planetary motion in the retaining ring 5 will be examined. The cause of the singularity is that the dust S attached to the lower surface of the top ring 3 is interposed between the semiconductor wafer 6 and the semiconductor wafer 6 as shown in FIG. Therefore, the convex portion is over-polished due to friction with the polishing cloth 23 on the turntable 20 during polishing.

That is, the insulating film formed on the surface of the semiconductor wafer 6 is shaved off more in the central portion of the convex portion as shown in FIG. 8 (a sectional view taken along the line AA 'in FIG. 7). As a result, the residual film amount is 0 at the center of the convex portion, and the residual film amount increases as the distance from the center increases, resulting in a contour line pattern as shown in FIG. 7 and a singular point on the surface of the semiconductor wafer 6. 6
Appears as a, 6a. This is because the semiconductor wafer 6 is fixed to the top ring 3 and the stress due to the dust S is locally concentrated. However, in this embodiment, since the semiconductor wafer 6 makes a planetary motion in the retaining ring 5 as described above, the convex portion which is over-polished due to the influence of dust is not limited to one point of the semiconductor wafer 6 and is always present. Since it moves, the influence of dust is averaged over the entire surface of the semiconductor wafer, and no singular point occurs. Therefore, the polishing surface of the object to be polished is highly accurately flat and mirror-finished.

As another example, the polishing apparatus and method of the present invention were used to polish a semiconductor wafer on which aluminum was deposited as a conductive film on the surface after patterning. Target wafer has a diameter of 6
Inch, form an insulating layer of silicon oxide on a silicon substrate, remove a part of the insulating layer by etching, provide a groove to form a pattern, and evaporate aluminum so as to fill the groove and cover the insulating layer. It was done. As a result of polishing, it was possible to prevent the occurrence of singular points due to dust on this wafer as well.

Although the vacuum suction mechanism is provided on the lower surface of the top ring 3 of the polishing section so that the semiconductor wafer 6 can be vacuum-sucked in the above embodiment, the polishing section of the polishing apparatus of the present invention is not limited to this. Instead of the one shown in FIG. 11, it may be one having no vacuum suction mechanism, that is, one having a structure in which the semiconductor wafer 6 cannot be sucked onto the lower surface of the top ring 3. In short, any structure may be used as long as the top ring has a structure in which the object to be polished makes a planetary motion in the retaining ring during polishing.

In the above embodiment, the polishing apparatus and method for polishing the semiconductor wafer to be flat and mirror-finished has been described as an example, but the polishing object to be polished by the polishing apparatus and method of the present invention is limited to the semiconductor wafer. Not a thing. Further, in the above embodiment, the case where one semiconductor wafer is polished with one top ring has been described, but holes for a plurality of semiconductor wafers are formed in the template-like top ring, and a plurality of semiconductor wafers are simultaneously formed. It may be polished. Further, in the above-described embodiment, the example in which the separate retaining ring is fixed to the top ring has been described, but the retaining ring may be formed integrally with the top ring.

[0044]

As described above, according to the present invention, the object to be polished is not fixed to the lower surface of the top ring, so that the object to be polished does not move integrally with the top ring during polishing, and the inside of the retaining ring is prevented. Since a kind of planetary motion is performed in the above, even if there is dust that entered between the top ring and the polishing object, the portion that is over-polished due to the influence of dust always moves, so polishing the polishing object There is no singular point on the surface, and the polishing object can be made flat and mirror-finished with high accuracy.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a polishing section of a polishing apparatus of the present invention.

FIG. 2 is a plan view of a polishing section of the polishing apparatus of the present invention.

FIG. 3 is a vertical cross-sectional view showing the overall configuration of the polishing apparatus of the present invention.

FIG. 4 is a diagram showing a relationship between a retaining ring and a polishing object of the polishing apparatus of the present invention.

FIG. 5 is a diagram for explaining a theory of rotation of a polishing object.

FIG. 6 is a diagram for explaining a cause of occurrence of a singular point on a polishing surface of a polishing object.

FIG. 7 is a diagram showing singular points generated on a polished surface of a polishing object.

FIG. 8 is a diagram showing a state of a residual film amount at a singular point.

9A and 9B are views for explaining an experimental example for confirming planetary motion on a polishing target object, FIG. 9A is a side view of the polishing target object with a flag, and FIG. 9B is a plan view thereof. FIG. 9C is a diagram showing a state in which the polishing object is set between the top ring and the turntable.

10 (a), (b), and (c) are diagrams showing a structure of a top ring used in an experiment.

FIG. 11 is a vertical sectional view showing another embodiment of the polishing portion of the polishing apparatus of the present invention.

[Explanation of symbols]

 1 Top Ring Drive Shaft 2 Ball Bearing 3 Top Ring 4 Top Ring Holder 5 Detachable Ring 6 Polishing Target 7,8 Torque Transmission Pin 9,11 Tube Joint 10 Vacuum Line Tube 12 Top Ring Cylinder 17 Polishing Abrasive Nozzle 20 Turn Table 21 axis 22 turntable ring 23 polishing cloth

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Riichiro Aoki 72 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Horikawa-cho factory (72) Hiroyuki Yano 72, Horikawa-cho, Kawasaki-shi, Kanagawa Incorporated in Toshiba Horikawa-cho Plant (72) Inventor Masako Kodera 72 Horikawa-cho, Saiwai-ku, Kawasaki City, Kanagawa Stock Company Incorporated Toshiba Horikawa-cho Plant (72) Inventor Atsushi Shigeta 72 Horikawa-cho, Kawasaki-shi, Kanagawa Company Toshiba Horikawa-cho factory (72) Inventor Yu Ishii 11-11 Haneda-Asahi-cho, Ota-ku, Tokyo Inside EBARA CORPORATION (72) Inventor Norio Kimura 11-11 Haneda-Asahi-cho, Ota-ku, Tokyo EBARA MFG. (72) Inventor Masayoshi Hirose 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Ebara Mfg. Co., Ltd. (72) Inventor Yukio Ikeda 11 Asahi-machi, Ota-ku, Tokyo The No. 1 Ebara Corporation

Claims (12)

[Claims] 1. A turntable having an upper surface covered with a polishing cloth and a top ring, wherein a polishing object is interposed between the turntable and the top ring to polish and flatten the surface of the polishing object. A polishing apparatus comprising: a turntable driving device that rotationally drives the turntable; a top ring driving device that rotationally drives the top ring; and a retaining ring for a polishing object provided on a lower surface of the top ring. , The bottom surface of the top ring that contacts the polishing object is formed smooth, and the inside diameter of the retaining ring is formed larger than the outside diameter of the polishing object, and the outer peripheral surface of the polishing object is disengaged by the rotation of the turntable. It comes into contact with the inner surface of the stop ring, and Wherein the latch ring polishing apparatus, characterized in that to the planetary motion to said polishing object by applying a rotational force to the polishing object. 2. The polishing apparatus according to claim 1, wherein the retaining ring is made of a resin material. 3. The top ring is provided with a plurality of suction ports, each of which has a tip opening on a lower surface of the top ring and communicates with a vacuum source, and the top ring is capable of vacuum-adsorbing an object to be polished. The polishing device according to claim 1. 4. The polishing apparatus according to claim 1, wherein the difference between the inner diameter of the retaining ring and the outer diameter of the object to be polished is 0.5 to 3 mm. 5. The polishing apparatus according to claim 1, wherein the polishing object is a semiconductor wafer, and an insulating film formed on the surface of the semiconductor wafer is polished. 6. The polishing apparatus according to claim 1, wherein the polishing object is a semiconductor wafer, and a conductive film formed on the surface of the semiconductor wafer is polished. 7. A turntable having an upper surface covered with a polishing cloth and a top ring, wherein a polishing object is interposed between the turntable and the top ring to polish and flatten the surface of the polishing object. In the polishing method, the step of rotating the turntable, the step of pressing the polishing object against the polishing cloth via the top ring, the step of rotating the top ring, and the polishing object by the rotation of the turntable. The outer peripheral surface of the top ring contacts the inner peripheral surface of the retaining ring which is provided on the lower surface of the top ring and forms a predetermined gap with the object to be polished, and the retaining ring is rotated to rotate the retaining ring. A step of imparting a rotational force to the object to cause the polishing object to make a planetary motion. Polishing method, characterized in that. 8. The outer diameter of the polishing object is D (m
m), the difference between the inner diameter of the retaining ring and the outer diameter of the object to be polished is d (mm), and the rotation speed of the top ring is r.
(Rpm) and polishing time is t (sec),
8. The polishing method according to claim 7, wherein the rotation speed r and the polishing time t are selected so that (d / D) .r.t ≧ 60. 9. A step of vacuum-adsorbing an object to be polished onto the lower surface of the top ring to carry it into a polishing position on the polishing cloth, and releasing the vacuum adsorption so that the object to be polished can freely move during the polishing step. The polishing method according to claim 7, further comprising: 10. The polishing method according to claim 9, further comprising a step of vacuum-adsorbing an object to be polished onto the lower surface of the top ring and carrying it out from the polishing cloth after the polishing is completed. 11. The polishing method according to claim 7, wherein the polishing object is a semiconductor wafer, and an insulating film formed on the surface of the semiconductor wafer is polished. 12. The polishing method according to claim 7, wherein the polishing object is a semiconductor wafer, and the conductive film formed on the surface of the semiconductor wafer is polished.