JP2001170857A - Dressing device and method for wafer polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent gradual progressing of inner and outer scraping of a polishing pad at dressing to improve uniformity in each process for wafer polishing and to diminish clogging of a dresser effectively to uniformly dress the polishing pad, improving machining accuracy of a wafer. SOLUTION: When the dresser 3 is pressed against the polishing pad 2 from upward for rotating the dresser 3 in the same direction as the polishing pad 2 by frictional force generated between the dresser 3 and the polishing pad 2 to dress surface of the polishing pad 2, circumference of the dresser 3 including a dressing face 3a is stuck out of upper side of the polishing pad 2 to outward of radial direction of the polishing pad 2 by a fixed length to a placed thereon. A cleaning device 6 for cleaning circumference of the dresser 3 stuck out of the polishing pad 2 is mounted on side of the polishing pad 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dressing apparatus and a dressing method for a polishing pad used in a wafer polishing apparatus.

[0002]

2. Description of the Related Art Generally, in a rotary wafer polishing apparatus for polishing a surface of a semiconductor wafer, a wafer polishing head for holding the wafer and a platen on which a polishing pad is attached are arranged to face each other, and the surface of the wafer is polished. The wafer is polished by rotating the polishing pad and rotating the wafer polishing head while planetary rotation or swinging on the polishing pad while supplying the slurry containing abrasive grains while pressing the pad against the pad.

[0003] In the above-mentioned wafer polishing apparatus, it has been found that when the wafer is repeatedly polished, the roughness of the polishing pad surface is reduced and the polishing performance is gradually reduced.
Therefore, each time the wafer is polished, the polishing pad is dressed using a polishing pad dressing apparatus as shown in FIG.

In FIG. 11, the dressing apparatus includes a dresser 11 attached to a dresser support portion 10 and an arm 12 for supporting the dresser 11 in a circumferential direction so that the dressing surface 11a faces downward. ing. A ball joint (not shown) is provided at a connection portion between the arm 12 and the dresser support portion 10, and the dressing surface 11 a of the dresser 11 is kept parallel to the polishing pad 14 regardless of the angle of the arm 12. It has become. Also,
The dresser 11 is moved vertically and horizontally toward and away from the polishing pad 14 attached to the platen 13 by the operation of an arm lifting / lowering mechanism and an arm advancing / retracting mechanism (both not shown) connected to the base end of the arm 12. It has become.

In the above dressing apparatus, the dresser 11
When the polishing pad 14 is rotated while pressing the polishing pad 14 against the polishing pad 14, the dresser 11 rotates in the same direction as the polishing pad 14 due to a frictional force generated between the dresser 11 and the polishing pad 14, and slides on the surface of the polishing pad 14. Sharpening is performed.

By the way, in a conventional dressing apparatus,
There is a tendency that the amount of dress (dressing amount) per dressing increases slightly toward the center of the polishing pad, though slightly. That is, each time the dressing is performed, the polishing pad is shaved in a mortar shape toward the center, and the degree of medium shaving gradually increases.

[0007] This is considered to be due to the fact that the dresser is arranged so as to fit within the area of the radius R of the polishing pad when viewed from vertically above. Incidentally, the dressing amount of the polishing pad is determined by the sliding length of the dresser abrasive grains at each position of the polishing pad when the contact pressure of the dresser is made uniform as in the following formula (I). z (x) = kL (x) P (x) (I) z (x): Dress amount at a distance x from the center of the polishing pad k: Proportional coefficient L (x): Center of the polishing pad Length of the abrasive grains at a distance x from the surface P (x): contact pressure of the dresser at a distance x from the center of the polishing pad

[0008] The sliding length L (x) is determined by the dresser rotation speed, the dresser abrasive grain surface shape, and the dresser abrasive grain density. Usually, the sliding length L (x) has a characteristic that it becomes longer at a portion near the center of the polishing pad.

[0009]

In the conventional dressing apparatus, the contact pressure of the dresser on the polishing pad becomes almost uniform by arranging the dresser so as to fit within the area of the radius R on the polishing pad. As can be seen from the formula (I), the amount of dressing on the inner peripheral side of the polishing pad having a relatively long sliding length of the abrasive grains increases, causing a phenomenon of medium shaving. Therefore, when dressing is repeatedly performed, the surface shape of the polishing pad gradually increases the negative gradient from the outer peripheral portion toward the center to increase the degree of the mortar shape, and as a result, the uniformity of each wafer polishing process is reduced. There is a problem of being damaged.

The variation in the uniformity of each process as described above has been small enough to be sufficiently tolerated in the past, but in recent years, the requirement for the uniformity has become strict.

To cope with this problem, the polishing pad is frequently replaced, for example, but the operating cost is increased.
Secondary problems have also arisen, such as the need to temporarily suspend operation for replacement.

Further, in the conventional dressing apparatus, when dressing the polishing pad, the dressing surface of the dresser is clogged with pad debris or slurry particles shaved off by the dresser, so that the dressing of the polishing pad becomes uneven. As a result, the processing accuracy of the wafer polished by the polishing pad decreases. Therefore, at present, dressing is dressed by spraying pure water on the dressing surface, or by washing the dresser in water and rinsing the dressing surface. At present, it is impossible to eliminate some clogging.

The present invention has been made in view of the above-mentioned circumstances, and keeps the dressing amount of the polishing pad uniform at each radial position to prevent the gradual and internal cutting of the polishing pad from progressing. It is another object of the present invention to provide a dressing apparatus and a dressing method for a wafer polishing pad, which can increase the uniformity of each wafer polishing process. It is another object of the present invention to provide a dressing apparatus and a dressing method for a wafer polishing pad that can effectively eliminate clogging of the dresser, uniformize the dress of the polishing pad, and improve the processing accuracy of the wafer.

[0014]

As a means for solving the above-mentioned problems, it is desirable to employ a dressing apparatus for a wafer polishing pad as described below. That is, in the present invention, a substantially disc-shaped dresser is pressed against a circular polishing pad rotating in the circumferential direction from above, and the dresser is rotated in the same direction as the polishing pad by a frictional force generated between the polishing pad and the polishing pad. What is claimed is: 1. A dressing apparatus for a wafer polishing pad for sharpening a pad surface, comprising: an arm for rotatably supporting the dresser and pressing the dresser from above against the polishing pad; and And a control unit for controlling the driving of the arm so as to protrude a predetermined length outward in the radial direction of the arm.

When the dresser is pressed against the polishing pad, a reaction force is applied from the polishing pad to each of the dressing surfaces of the dresser. However, the dresser is polished while maintaining a state in which a part of the annular area requiring the dressing is covered. If the pad shifts radially outward and the peripheral edge protrudes from the polishing pad by a predetermined length, the balance of the reaction force acting on the dresser is broken, and the dresser has a vertical position including the radial direction of the polishing pad. A moment acts to push up the peripheral edge located at the center side of the polishing pad in the plane upwards, and the ball joint provided between the arm and the dresser also works, resulting in the dresser becoming a polishing pad. Slightly inclined with the peripheral edge located on the center side of the upper side facing upward. When the dresser is tilted in this manner, the contact pressure of the dresser on the polishing pad surface increases from the center of the polishing pad toward the outer peripheral portion.

According to the present invention, the characteristic that the surface shape of the polishing pad gradually increases the negative gradient from the outer peripheral portion toward the center every time the dressing is repeated is changed by the contact pressure of the dresser from the center of the polishing pad toward the outer peripheral portion. By progressively increasing. As a result, the dress amount of the polishing pad is kept uniform.

By the way, the protruding amount (length) of the dresser
As the amount of reaction increases, the balance of the reaction force acting on the dresser breaks down, and the inclination of the dresser becomes tight, and the gradient seen in the contact pressure distribution of the dresser becomes unnecessarily large. Is cut into an umbrella shape toward the center (cut outside).

From this, it can be understood that the dresser disposed so as to protrude from the polishing pad has an appropriate position. Therefore, in the present invention, by setting the protruding amount to an appropriate size, the middle and outer shavings of the polishing pad are prevented from gradually progressing, and the dress amount is kept uniform.

In the dressing device for a wafer polishing pad according to the present invention, the dresser may be a dresser having a dressing surface provided below the peripheral portion, and the dresser may be disposed on a side of the polishing pad at a peripheral portion protruding from the polishing pad. A cleaning device that sprays a cleaning liquid and cleans the cleaning liquid may be used. This allows Dresser's
The dressing surface provided on the peripheral portion protruding from the polishing pad can be cleaned to eliminate clogging of the dressing dressing surface accumulated in the dress.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a dressing apparatus and a dressing method for a wafer polishing head according to the present invention will be described with reference to FIGS. In FIG.
1 is a platen, 2 is a polishing pad, 3 is a dresser, 4
Denotes an arm, 5 denotes a control unit, and 6 denotes a cleaning device. The polishing pad 2 is affixed on the platen 1 so that the central axes are aligned,
It rotates around the axis. The dresser 3 is rotatably supported in the circumferential direction at the tip of the arm 4 with the dressing surface 3a facing downward. Here, the dresser 3 is formed such that the inner peripheral side of the lower surface is formed in a concave shape, and a dressing surface 3 a is formed below the peripheral portion of the dresser 3. The control unit 5 controls the operation of an arm elevating mechanism and an arm advancing / retracting mechanism (not shown), and arranges the dresser 3 at a predetermined position so as to approach and separate vertically and horizontally from the polishing pad 2. The cleaning device 6 supplies a cleaning liquid supplied from a cleaning liquid supply source 6 a, in this embodiment, pure water, to a peripheral portion (a dressing surface 3) of the dresser 3 protruding from the polishing pad 2 beside the polishing pad 2.
a) and a cleaning nozzle 6b for spraying pure water onto the cleaning nozzle 6b.

In FIG. 1, R is the outer radius of the polishing pad 2, w is the radial width of the polishing pad 2 in an annular area (hereinafter referred to as a dressing area) A requiring polishing, r
Is the center radius of the dressing area A, D is the outer diameter of the dresser 3, a
Is the distance between the centers of the polishing pad 2 and the dresser 3.

With respect to the polishing pad 2 and the dresser 3, the sizes and positions to be arranged are determined under the following conditions when dressing is performed. w ≦ D (II) | ar | <| (D−w) / 2 | (III) R <a + D / 2 (IV) D / 2 <a (V)

The condition (II) is provided so as not to leave an unsharpened portion in the sharpening area A. Condition (III)
Is given so that the dresser 3 does not deviate from the dressing area A. The condition (IV) is given so that the peripheral portion of the dresser 3 protrudes outward from the polishing pad 2 in the radial direction. Condition (V) is that the periphery of the dresser 3 is the polishing pad 2
Given to not cover the center of the.

Next, a description will be given of a process of a dressing process for the polishing pad 2 after the wafer polishing process. When the wafer polishing process is completed, a wafer polishing head (not shown) holding the wafer retreats from above the polishing pad 2, and the dresser 3 supported by the arm 4 moves onto the polishing pad 2 instead.

At this time, the dresser 3 controls the driving of the arm 4 by the control unit 5 so that the conditions (II) and (II)
While maintaining the state of satisfying (I), (IV), and (V) and covering a part of the dressing region A in the range of the width w, the peripheral edge thereof is radially outward from the polishing pad 2 by a length Δ. It is arranged to protrude.

The periphery of the dresser 3 is placed on the polishing pad 2 from above.
As shown in FIG.
Center C of sa3_DPosition radially inward of the polishing pad 2
Placed part is center C_DPart located more radially outward than
Dresser 3
The balance of the reaction force F acting on the surface is broken. This allows
The dresser 3 has a vertical surface including the radial direction of the polishing pad 2.
Center C of polishing pad 2 _PPush the peripheral part located on the
The lifting moment M acts, and the arm and the
The ball joint provided between the 3
As a result, the dresser 3 is located on the center side of the polishing pad 2 as a result.
It is slightly inclined with the peripheral edge located upward. This
When the dresser 3 tilts, the dresser 3
The contact pressure P of the dresser 3 is from the center of the polishing pad 2 to the outer periphery.
It becomes bigger toward the section.

If a positive gradient is generated in the distribution of the contact pressure P of the dresser 3 from the center of the polishing pad 2 toward the outer peripheral portion, the characteristic that the surface shape of the polishing pad 2 produces a negative gradient from the outer peripheral portion toward the center is canceled. Thus, the dress amount at each location in the radial direction of the polishing pad 2 shows a close value.

By the way, when the amount of protrusion Δ of the dresser 3 is increased, the balance of the reaction force acting on the dresser 3 is broken, and the inclination of the dresser 3 becomes sharp. As a result, the distribution of the contact pressure P is observed. The positive gradient also becomes unnecessarily large, so that the polishing pad 2 is finally shaved. As can be seen from the equation (I), if an appropriate amount of protrusion Δ is given, the dress amount shows a substantially constant value.

Therefore, in order to find an appropriate value of the amount of protrusion Δ, the dresser 3 is shifted stepwise to the outside of the polishing pad 2 in the radial direction, and the dressing 3 is shifted to the outside of the polishing pad 2 in the radial direction at each amount of protrusion Δ. The gradient of the speed (the amount of dress per unit time) was measured. The result is shown in FIG. The arrangement conditions at this time are: D = 405 mm, R = 45
0 mm, rotation speed of polishing pad 2 25 rpm, dresser 3
Is 25 rpm. Here, the shape of the dressing surface 3a of the dresser 3 is a simple ring shape in which the dressing surface 3a is formed on the entire lower periphery of the dresser 3.

According to FIG. 3, when the protrusion amount Δ is set to 3 mm, the dressing speed becomes large on the inner peripheral side of the polishing pad 2 and becomes smaller on the outer peripheral side, and a negative gradient is generated outward in the radial direction. When the protrusion amount Δ is set to 15 mm, the dressing speed becomes substantially uniform (no gradient) at each radial position of the polishing pad 2. When the protrusion amount Δ is set to 50 mm, the dress amount becomes smaller on the inner peripheral side of the polishing pad 2 and becomes larger on the outer peripheral side, and a positive gradient is generated outward in the radial direction.

From this, it is understood that the appropriate protrusion amount Δ of the dresser 3 in this case is about 15 ± 2 mm. That is, by setting the protruding amount Δ within the above range, it is possible to prevent the inside and outside shavings of the polishing pad 2 from gradually progressing, and to make the dress amount uniform at each location in the radial direction of the polishing pad 2. You can keep it.

FIG. 4 shows that the amount of protrusion Δ of the dresser 3 is 3
The results of measuring the dressing speed on the surface of the polishing pad 2 at each protrusion amount Δ when the values are set to mm, 15 mm, and 50 mm are shown. In FIG. 4, the horizontal axis of the graph is the distance from the center of the polishing pad 2, and the vertical axis is the dressing speed.

FIG. 4 shows that when the protrusion amount Δ is 3 mm, the dressing speed on the surface of the polishing pad 2 has a negative gradient toward the outside in the radial direction, and a phenomenon of medium scraping has occurred. When the amount of protrusion Δ is set to 15 mm, the dressing speed is substantially uniform at each position of the polishing pad 2 in the radial direction. Then, the protrusion amount Δ is set to 5
When the distance is set to 0 mm, the dressing speed on the surface of the polishing pad 2 has a negative gradient toward the outside in the radial direction, which causes the phenomenon of external shaving.

Next, FIG. 5 shows the results of measurement of the state of undulation of the surface of the polishing pad 2 after an elapse of an arbitrary time after setting the protrusion amount Δ of the dresser 3 to 15 mm which is considered to be an optimum value. In FIG. 5, the horizontal axis of the graph is the distance from the center of the polishing pad 2, and the vertical axis is the height of the polishing pad 2 from the upper surface of the platen 1. The measurement was performed by setting an arbitrary polishing pad state to a state before the start of the dressing, 70 minutes from the start of the dressing, and 19 minutes.
Each test was performed after 0 min.

According to FIG. 5, although the surface of the polishing pad 2 has a slight negative gradient outward in the radial direction, the gradient is 70 min.
After the dressing was performed at 90 min., There was almost no change. This shows that the shape of the surface of the polishing pad 2 is kept constant even if the dressing is repeatedly performed.

For comparison with FIG. 5, FIG. 6 shows the result of measurement of the undulation of the surface of the polishing pad 2 after an arbitrary time has passed without the dresser 3 protruding (the protrusion amount Δ is set to 0 mm). (In FIG. 6, as the dresser 3,
D shows data when a dresser of 305 mm is used). The measurement was carried out before the start of the dressing, and after 80 min. And 280 min. From the start of the dressing, with an arbitrary polishing pad being in a state before the start of the dressing.

According to FIG. 6, the surface of the polishing pad 2 before the start of the dressing had a negative gradient toward the outside in the radial direction, but the surface of the polishing pad 2 after a lapse of 80 min. It has been stolen. 280 from the start of dressing
After the elapse of min., the surface of the polishing pad 2 has a positive gradient outward in the radial direction, indicating that the medium is polished.

Next, a description will be given of a measurement result obtained when the same measurement is performed when the dresser 3 has a different shape from the previous dresser under the same conditions as those described above. The shape of the dressing surface 3a of the dresser 3 used at this time is not a simple ring shape but a special shape for finishing the surface shape of the polishing pad 2 flat.
When viewed from the lower surface of the, it has a shape like the contour of a four-leaf clover.

According to FIG. 7, the protrusion amount Δ is 0 mm, 1
When it is set to 5 mm, the dressing speed is large on the inner peripheral side of the polishing pad 2 and becomes smaller on the outer peripheral side, and a negative gradient is generated outward in the radial direction. When the protrusion amount Δ is set to 25 mm, the dressing speed is substantially uniform (no gradient) at each radial position of the polishing pad 2. When the protrusion amount .DELTA. Is set to 35 mm or 70 mm, the dress amount becomes smaller on the inner peripheral side of the polishing pad 2 and becomes larger on the outer peripheral side, and a positive gradient is generated outward in the radial direction.

From this, it is understood that the appropriate protrusion amount Δ of the dresser 3 in this case is about 25 ± 2 mm. That is, by setting the protruding amount Δ within the above range, it is possible to prevent the inside and outside shavings of the polishing pad 2 from gradually progressing, and to make the dress amount uniform at each location in the radial direction of the polishing pad 2. You can keep it.

FIG. 8 shows that the amount of protrusion Δ of the dresser 3 is set to 0.
The results of measuring the dressing speed on the surface of the polishing pad 2 at each protrusion amount Δ when the values are set to mm, 25 mm, and 35 mm are shown. 8, the horizontal axis of the graph is the distance from the center of the polishing pad 2, and the vertical axis is the dressing speed.

FIG. 8 shows that when the amount of protrusion Δ is 0 mm, the dressing speed on the surface of the polishing pad 2 has a negative gradient toward the outside in the radial direction, and a phenomenon of medium scraping has occurred. When the protrusion amount Δ is set to 25 mm, the dressing speed is substantially uniform at each radial position of the polishing pad 2. Then, the protrusion amount Δ is set to 3
When the thickness is set to 5 mm, the dressing speed on the surface of the polishing pad 2 has a negative gradient toward the outside in the radial direction, and the phenomenon of external shaving has occurred.

Next, FIG. 9 shows the result of measurement of the state of undulation of the surface of the polishing pad 2 after an elapse of an arbitrary time after setting the protrusion amount Δ of the dresser 3 to 25 mm which is considered to be an optimum value. In FIG. 9, the horizontal axis of the graph is the distance from the center of the polishing pad 2, and the vertical axis is the height of the polishing pad 2 from the upper surface of the platen 1. The measurement was performed by setting the state of an arbitrary polishing pad to a state before the start of dressing, and 30 minutes (minutes) and 60 minutes after the start of the dressing.
After each elapse of min.

According to FIG. 9, the surface of the polishing pad 2 has a slight negative gradient toward the outside in the radial direction, but the gradient is 30 min.
0min. And hardly changed after dressing. This shows that the shape of the surface of the polishing pad 2 is kept constant even if the dressing is repeatedly performed.

For comparison with FIG. 9, FIG. 10 shows the result of measurement of the undulation of the surface of the polishing pad 2 after an elapse of an arbitrary time without the dresser 3 protruding (the protruding amount Δ was set to 0 mm). Show. Note that the measurement was performed by setting an arbitrary polishing pad state to a state before the start of dressing, and 40 min. And 70 min. Before the start of the dressing.
, 100 minutes.

According to FIG. 10, the surface of the polishing pad 2 before the start of dressing had a negative gradient toward the outside in the radial direction, but the surface of the polishing pad 2 after the passage of 40 min. It has been stolen. And 70 from the start of dressing
After a lapse of min., the surface of the polishing pad 2 has a positive gradient in the radially outward direction, and after a lapse of 100 min., the gradient is further strengthened.

Here, when polishing the polishing pad 2,
The dressing surface 3a of the dresser 3, which is rotated while protruding with an appropriate protruding amount as described above, is cleaned by the cleaning device 6.
(See FIG. 2). As a result, the clogging of the dressing surface 3a of the dresser 3 that accumulates during the dressing can be eliminated, so that the dressing of the polishing pad 2 is uniform even during the dressing, and the processing accuracy of the wafer polished by the polishing pad 2 is improved. Can be improved.

The shape of the dressing surface 3a of the dresser 3 is the same as the shape described in the above embodiment, and the lower surface is formed in a flat or complicated pattern, and the entire lower surface or a part thereof is the dressing surface 3a. It may be.

[0049]

As described above, according to the present invention,
By arranging the peripheral portion of the dresser so as to protrude from the polishing pad by a predetermined length to the outside in the radial direction of the polishing pad, the distribution of the contact pressure of the dresser from the center of the polishing pad toward the outer peripheral portion has a positive gradient. Is generated, and the characteristic that the surface shape of the polishing pad produces a negative gradient from the outer peripheral portion toward the center is canceled. By this, the dressing amount of the polishing pad is kept uniform at each location in the radial direction, and the inside and outside shavings of the polishing pad are prevented from gradually progressing,
The uniformity of each wafer polishing process can be improved.

Further, according to the present invention, when the gradient of the initial surface shape of the polishing pad is not flat, for example, when the polishing pad has a positive gradient from the outer peripheral portion toward the center, the protrusion amount is set to a value smaller than the optimum value. If the dressing is performed with a negative gradient from the outer periphery toward the center, the amount of protrusion is set to a value larger than the optimum value, and dressing is performed in each case to obtain a flat surface shape with a gradient. After that, by setting the amount of protrusion to the optimum value and performing dressing, not only the uniformity of each wafer polishing process but also the uniformity of the wafer polishing itself can be improved.

Further, according to the present invention, since the clogging of the dressing surface of the dresser which accumulates in the dress can be eliminated, the dress of the polishing pad can be made uniform even during the dress, and the wafer to be polished by the polishing pad can be made uniform. Processing accuracy can be improved.

The dressing apparatus described in the present embodiment is a system in which the dresser is rotated by a frictional force generated between the dresser and the rotating polishing pad when the dresser is pressed against the polishing pad. It is needless to say that the same effect as described above can be obtained even if a method of controlling the number by a motor or the like is adopted.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is a schematic view showing an arrangement of a dresser and a cleaning device with respect to a polishing pad.

FIG. 2 is a state explanatory view showing a balanced state of forces acting between a polishing pad and a dresser, and showing a cleaning state of a dresser by a cleaning device.

[Figure 3] Using a dresser whose dressing surface is substantially ring-shaped,
4 is a table showing a gradient of a dress amount with respect to a radial outside of a polishing pad in each protrusion amount given to a dresser.

Fig. 4 Using a dresser whose dressing surface is substantially ring-shaped,
4 is a table showing the difference in dress speed distribution on the polishing pad surface for each protrusion amount Δ when the protrusion amount of the dresser is set to each of 3 mm, 15 mm, and 50 mm.

FIG. 5: Using a dresser having a substantially ring-shaped dressing surface,
FIG. 9 is a table showing the state of the undulation of the polishing pad surface after an elapse of an arbitrary time after the amount of protrusion of the dresser is set to 15 mm which is considered to be an optimum value.

FIG. 6: Using a dresser having a substantially ring-shaped dressing surface,
4 is a chart showing the state of undulation of the polishing pad surface after an arbitrary time has elapsed without protruding the dresser.

FIG. 7 is a chart showing a gradient of a dress amount with respect to a radially outward direction of a polishing pad at each protrusion amount given to the dresser, using a dresser having a contoured surface shaped like a contour of a four-leaf clover. is there.

FIG. 8 shows the relationship between the amount of protrusion Δ when the amount of protrusion of the dresser is set to each of 0 mm, 25 mm, and 35 mm using a dresser whose sharpening surface is shaped like the contour of a four-leaf clover. 4 is a chart showing a difference in dress speed distribution on the polishing pad surface.

FIG. 9: Using a dresser whose sharpening surface is shaped like a contour line of a four-leaf clover, setting the amount of protrusion of the dresser to 25 mm which is considered to be an optimum value, and polishing after elapse of an arbitrary time. It is a chart which shows the state of undulation of the pad surface.

FIG. 10 is a chart showing a state of undulation of the polishing pad surface after elapse of an arbitrary time without using a dresser having a dressing surface shaped like a contour of a four-leaf clover.

FIG. 11 is a side sectional view showing a configuration of a conventional dressing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Platen 2 Polishing pad 3 Dresser 3a Dressing surface 4 Arm 5 Control part 6 Cleaning device Δ Extrusion amount A Dressing area

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masato Komazaki 1-297 Kitabukuro-cho, Omiya-shi, Saitama Prefecture Mitsubishi Materials Research Institute (72) Inventor Jiro Sano 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materials Hiroyuki Kobayashi (72) Inventor Hiroyuki Kobayashi 1-297 Kitabukuro-cho, Omiya-shi, Saitama F-term (reference) Mitsubishi Materials Corporation Research Laboratory 3C047 AA21 AA34 BB01 3C058 AA09 AA19 AC04 DA17

Claims (4)

[Claims] 1. A polishing method in which a generally disc-shaped dresser is pressed against a circular polishing pad rotating in a circumferential direction from above, and the dresser is rotated in the same direction as the polishing pad by a frictional force generated between the polishing pad and the polishing pad. A dressing device for a wafer polishing pad for sharpening a pad surface, comprising: an arm for rotatably supporting the dresser and pressing the dresser from above against the polishing pad; and a peripheral portion of the dresser from above the polishing pad. A control unit for controlling the driving of the arm so as to protrude outward by a predetermined length in the radial direction of the wafer polishing pad. 2. A dresser having a dressing surface provided below a peripheral portion of the dresser, and a cleaning solution is sprayed on a side of the polishing pad on a peripheral portion of the dresser protruding from the polishing pad to clean the dresser. The dressing device for a wafer polishing pad according to claim 1, further comprising a cleaning device. 3. A polishing method in which a generally disc-shaped dresser is pressed against a circular polishing pad rotating in a circumferential direction from above, and the dresser is rotated in the same direction as the polishing pad by frictional force generated between the polishing pad and the polishing pad. A dressing method for a wafer polishing pad for sharpening a pad surface, wherein a peripheral portion of the dresser is arranged so as to protrude from the polishing pad by a predetermined length outward in a radial direction of the polishing pad. Dressing method for wafer polishing pad. 4. A dresser having a dressing surface provided below a peripheral portion as the dresser, wherein a cleaning solution is sprayed on a peripheral portion of the dresser protruding from the polishing pad to clean the peripheral portion. A dressing method for a wafer polishing pad as described in the above.