JP2018039079A - Polishing pad - Google Patents

Abstract

[Problem] To provide a polishing pad capable of suppressing polishing unevenness. [Solution] A polishing pad (100) according to the present invention has a polishing surface (101a) on which a plurality of grooves (101b) extending in the same direction are formed. The depth (H1) of the plurality of grooves (101b) is uniform, and the coefficient of variation for the width (D1) of the plurality of grooves (H1), calculated by the following [Equation 1], is 0.05 or more and 0.30 or less, and the land width (D2), which is the width of lands (101c) on the polishing surface (101a) between the plurality of grooves (101b) in a direction perpendicular to the extension direction of the grooves (101b), is constant. Coefficient of variation = (standard deviation of groove width (D1)) / (average value of groove width (D1)) [Equation 1] [Selected Figure] Figure 5

Description

  The present invention relates to a polishing pad used for polishing glass substrates, hard disk substrates, silicon wafers, semiconductor devices and the like.

  A polishing pad is used for polishing optical materials, semiconductor devices, hard disk substrates, and the like. The polishing pad is made of a hard pad made of a synthetic resin such as polyurethane, a soft suede pad, a non-woven fabric made of a synthetic fiber such as polyethylene terephthalate (PET), and the like, and has predetermined polishing characteristics depending on physical properties, distribution of voids, and the like.

  A groove for diffusing the polishing slurry may be formed on the surface of the polishing pad. However, a polishing pad having a plurality of grooves extending in the same direction has a regular shape that extends while maintaining a constant distance between the grooves, and the grooves or lands (areas where no grooves are formed) and the object to be polished Locations that come into contact with the object are synchronized with the polishing, and may be locally excessively polished or insufficiently polished.

  In contrast, for example, Patent Document 1 discloses a polishing apparatus that prevents synchronization by rotating and simultaneously revolving a polishing pad while rotating an object to be polished during polishing. Further, Patent Document 2 discloses a polishing pad having two types of grooves having different depths. By dispersing the groove volume, it is possible to suppress a change with time due to wear of the grooves. Further, Patent Document 3 discloses a grooved resin pad for processing semiconductor devices with an irregular groove pitch in order to suppress hydroplane due to polishing slurry.

JP 2012-143822 A JP 2006-346856 A JP 2002-184730 A

  However, the polishing apparatus described in Patent Document 1, polishing by shifting the rotation speed of the upper surface plate and the lower surface plate, sliding the holding surface plate side holding the object to be polished within a certain range, etc. Even if an attempt is made to cope with the structure of the polishing apparatus and the polishing method for reducing the transfer of the polishing pad groove shape, further adjustment is required to reduce the synchronization (for example, periodic waviness around 10 mm) while maintaining the polishing accuracy. In addition, it is necessary to adjust polishing conditions and the like every time the polishing pad is different.

  As described in Patent Document 2, when changing the groove depth for each groove while keeping the land width constant, the contact point between the groove or the land and the object to be polished does not change. It is enough. Furthermore, if the groove depth differs between the grooves, the amount of slurry supplied to the polishing surface differs, which may adversely affect the uniformity.

  Further, as in Patent Document 3, when the land width is irregular with the groove width being constant, the diffusibility of the polishing slurry becomes non-uniform. For example, since the amount of polishing slurry is relatively reduced at locations where the land width is wide and the amount of polishing slurry is relatively increased at locations where the land is narrow, it is not possible to reliably suppress the occurrence of polishing streaks and polishing unevenness. Similarly, there is a problem that the abrasive waste discharging property is relatively deteriorated in a portion having a wide land width.

  In view of the circumstances as described above, an object of the present invention is to provide a polishing pad that can suppress uneven polishing despite including a groove extending in the same direction.

In order to achieve the above object, a polishing pad according to one embodiment of the present invention has a plurality of grooves extending in the same direction on a polishing surface. The depth of the plurality of grooves is uniform, and the variation coefficient calculated by the following [Formula 1] for the width of the plurality of grooves is 0.05 or more and 0.30 or less. The land, which is the width in the direction perpendicular to the extending direction of the grooves, of the land, which is the polishing surface, is uniform.
Coefficient of variation = (standard deviation of groove width) / (average value of groove width) [Formula 1]

  According to this configuration, by controlling the variation of the groove width within a certain range, it is possible to effectively prevent periodic polishing unevenness due to synchronization between the polishing layer and the object to be polished. Further, by making the land width and groove depth uniform, the diffusibility and fluidity of the polishing slurry flowing through the groove become uniform, and in this respect as well, the occurrence of polishing unevenness can be suppressed.

  The plurality of grooves may be stripe grooves extending parallel to each other on the polishing surface.

  A lattice groove pattern in which two types of the stripe grooves are overlapped may be provided on the polished surface.

  The plurality of grooves may be concentric circular grooves that are concentric on the polishing surface.

  On the polishing surface, a plurality of groove patterns configured by stripe grooves in which the plurality of grooves extend in parallel with each other may be provided.

  On the polishing surface, a groove cutting pattern composed of 10 or more of the plurality of grooves may be repeatedly provided twice or more.

  As described above, according to the present invention, it is possible to provide a polishing pad capable of suppressing polishing unevenness.

1 is a perspective view of a polishing pad according to an embodiment of the present invention. It is a top view of the polishing pad. It is a schematic plan view of the polishing pad. It is sectional drawing of the same polishing pad. It is a typical sectional view of the polishing pad. It is a top view which shows the other groove shape of the polishing pad. It is a top view which shows the other groove shape of the polishing pad. It is a top view which shows the other groove shape of the polishing pad.

  A polishing pad according to an embodiment of the present invention will be described.

[Configuration of polishing pad]
FIG. 1 is a perspective view showing a polishing pad 100 according to this embodiment. As shown in the figure, the polishing pad 100 includes a polishing layer 101, an adhesive layer 102, and a cushion layer 103. Hereinafter, in each figure, three directions orthogonal to each other are defined as an X direction, a Y direction, and a Z direction.

  The polishing layer 101 is a layer that contacts the object to be polished and performs polishing. Hereinafter, the surface of the polishing layer 101 is referred to as a polishing surface 101a. A groove 101b is formed on the polishing surface 101a. A region between the grooves 101b in the polished surface 101a is referred to as a land 101c. Details of the groove 101b and the land 101c will be described later.

  The material of the polishing layer 101 is not particularly limited, and can be made of a synthetic resin such as a polyurethane resin. The polyurethane resin may be, for example, a mixture of a prepolymer that is an isocyanate compound and a polyol curing agent or a polyamine curing agent. Bubbles or the like for improving the polishing characteristics may be formed in the polishing layer 101. The bubbles can be formed by utilizing foaming using hollow fine particles, chemical foaming, mechanical foaming, or the like, and tear-type bubbles may be formed by a wet film forming method. The material of the polishing layer 101 is not limited to polyurethane resin, and can be made of a known material. For example, it may be composed of a nonwoven fabric, a woven fabric, a knitted fabric, or a substrate such as a nonwoven fabric impregnated with a synthetic resin such as a polyurethane resin, and a known abrasive grain, pigment, dye, additive, etc. It may be included. However, if the Shore A hardness of the polishing layer 102 is 20 or more, preferably 60 or more, the structure of the grooves and lands described later is less likely to change during polishing, and the effects of the present invention tend to be obtained stably. On the other hand, if the Shore D hardness of the polishing layer 102 is 99 or less, preferably 80 or less, excessive scratches tend to be suppressed.

  The adhesive layer 102 is a layer that adheres the polishing layer 101 and the cushion layer 103, and is, for example, an adhesive tape.

  The cushion layer 103 is a layer that makes the contact of the polishing layer 101 with the object to be polished uniform. The cushion layer 103 can be made of a flexible material such as a nonwoven fabric or a synthetic resin. Of course, you may have a hard support layer.

  The polishing pad 100 is attached to the polishing apparatus with an adhesive tape or the like disposed on the cushion layer 103. The size (diameter) of the polishing pad 100 can be determined according to the size of the polishing apparatus and the like, and can be, for example, a disk shape having a diameter of about 10 cm to 2 m. Note that the shape of the polishing pad 100 is not limited to a disk shape, and may be a rectangular shape, a belt shape, or the like.

  In addition, the polishing pad 100 only needs to have at least the polishing layer 101, and may be one without the adhesive layer 102 and the cushion layer 103, or one in which the polishing layer 101 is directly laminated on the cushion layer 103.

  The polishing pad 100 is rotationally driven while being pressed against the object to be polished by the polishing apparatus, and polishes the object to be polished. At that time, a polishing slurry is supplied between the polishing pad 100 and the object to be polished. The polishing slurry is supplied to the polishing surface 101a through the groove 101b and discharged.

[About the structure of grooves and lands]
FIG. 2 is a plan view of the polishing layer 101, and FIG. 3 is a schematic enlarged plan view of the polishing layer 101. 4 is a cross-sectional view of the polishing layer 101, and FIG. 5 is a schematic cross-sectional view of the polishing layer 101.

  As shown in FIG. 2, the polishing surface 101a has a plurality of grooves 101b extending in the same direction. The grooves 101b can be stripe grooves extending parallel to each other on the polishing surface 101a. In FIG. 3, the extending direction of the groove 101b is shown as a line L1, and the direction orthogonal to the extending direction (line L1) of the groove 101b is shown as a line L2. The number of grooves 101b is not particularly limited.

  As shown in FIG. 4, the groove 101b is formed in the polishing layer 101 from the polishing surface 101a to a certain depth. The cross-sectional shape of the groove 101b is not particularly limited, but can be rectangular as shown in FIG.

  As shown in FIG. 5, the width of the groove 101b is defined as a groove width D1, and the depth of the groove 101b from the polishing surface 101a is defined as a groove depth H1. The groove width D1 is a width along a direction (line L2) orthogonal to the extending direction (line L1) of the groove 101b. Here, the groove depth H1 is uniform in each of the grooves 101b, and the groove depth H1 is uniform among the plurality of grooves 101b.

  As shown in FIGS. 3 and 5, the width of the land 101c along the direction (line L2) perpendicular to the extending direction (line L1) of the groove 101b is defined as a width D2. The width D2 of each land 101c is uniform.

  The polishing layer 101 according to this embodiment is configured such that a coefficient of variation (CV) calculated by the following [Equation 1] is 0.05 or more and 0.30 or less.

  Variation coefficient = (standard deviation of groove width D1) / (average value of groove width D1) [Formula 1]

  As described above, the coefficient of variation is made dimensionless by dividing the standard deviation unit by the average value, and can be applied without depending on the average value of the groove width D1. In order to increase the coefficient of variation, the variation (standard deviation) between the groove widths D1 may be increased, and to decrease, the variation (standard deviation) may be decreased. The groove width D1 is not particularly limited, but in consideration of slurry fluidity, polishing rate, etc., it is preferably set within a range of 0.2 mm to 10 mm, more preferably 0.2 mm to 5 mm. More preferably, it is 0.3 mm or more and 3 mm or less.

  The coefficient of variation is set to 0.05 or more and 0.30 or less, that is, by controlling the variation in the groove width D1 within a certain range, the polishing layer 101 and the object to be polished are synchronized (the specific portion of the polishing layer 101 is the position of the object to be polished) It is possible to effectively prevent periodic polishing unevenness due to continuous sliding at a specific location), and to achieve both prevention of synchronization and suppression of polishing unevenness due to variations in the groove width D1. Note that the coefficient of variation is preferably set to 0.05 or more and 0.20 or less from the viewpoint of more surely suppressing polishing unevenness due to variations in the groove width D1. Here, in order to more surely eliminate regularity and prevent synchronization, it is preferable that the minimum unit for repeating the groove is 10 or more. For the same reason, it is preferable that the minimum unit width of the groove is 50 mm or more.

  With regard to the variation between the groove widths D1, the effect of the present invention can be obtained more reliably if the regularity is eliminated, but industrially, for example, 5, 10, or 20 irregular groove widths D1. The manufacturing cost can be reduced by repeatedly providing the groove cutting pattern having 2 or more times. Here, if the minimum unit of repeating grooves is 9 or less, regularity becomes strong, and therefore, uneven polishing may occur due to synchronization. Here, in order to more surely eliminate regularity and prevent synchronization, it is preferable that the minimum unit for repeating the groove is 10 or more. For the same reason, it is preferable that the minimum unit width of the groove is 50 mm or more.

  In addition, by making the land width D2 and the groove depth H1 uniform, the diffusibility and fluidity of the polishing slurry become uniform in each land 101c and groove 101b, and also in this respect, the occurrence of polishing unevenness can be suppressed. it can. For example, if the land width D2 and the groove depth H1 are both within the average value ± 0.2 mm, more preferably within the average value ± 0.1 mm, the effects of the present invention can be obtained more reliably. it can. The land width D2 is not particularly limited, but in consideration of the polishing rate and the like, it is preferably set within a range of 0.3 mm to 30 mm, more preferably 0.5 mm to 20 mm, and 1.0 mm to 10 mm. The following is more preferable. The groove depth H1 is not particularly limited, but is preferably set within a range of 0.5 mm or more and 3 mm or less in consideration of slurry fluidity and polishing rate. Note that the present invention is particularly effective for secondary polishing (finish polishing) in which polishing dust discharge (scratch suppression) and polishing accuracy are important.

  From the viewpoint of achieving both suppression of synchronization between the polishing layer 101 and the object to be polished and suppression of polishing unevenness due to variations in the groove width D1, it is preferable to keep the variation in the groove width D1 within a certain range. Specifically, with respect to the maximum value D1max and the minimum value D1min of the groove width D1 of the plurality of grooves, the ratio D1max / D1min is preferably 1.1 or more and 3.0 or less, and 1.1 or more and 2 or less. More preferably, it is 0.0 or less. For the same reason, D1max is preferably less than twice the average value of D1, and D1min is preferably more than half of the average value of D1.

  The groove width D1 and the land width D2 can be measured by using a caliper, and for each groove or land, the points excluding the intersection part of the groove, the through-hole processed part, the bubble part, etc. are obtained. Can do. When calipers cannot be used because the polishing layer is soft, the image may be analyzed from the image of the polishing surface, and the sample is perpendicular to the polishing surface and in the extending direction of the groove 101b (line L1). Image analysis may be performed from an image of a cross section cut in an orthogonal direction (line L2), or a laser displacement meter may be used. In addition, when the cross-sectional shape of a groove | channel contains slopes, such as a trapezoid, the numerical value in the grinding | polishing surface surface is made into groove width D1 or land width D2. By measuring the groove width D1 and the land width D2 for all the grooves in the region and applying the [Formula 1], the coefficient of variation CV in the region can be calculated. Here, if the coefficient of variation CV is 0.05 or more and 0.30 or less in a region where the plurality of grooves 101b are preferably 10 or more, more preferably 20 or more, both synchronization and prevention of uneven polishing can be more reliably achieved. it can. The groove depth H1 can be calculated by image analysis from an image of a cross section obtained by cutting the sample perpendicular to the polished surface, but a laser displacement meter may be used. Each groove can be obtained by measuring a portion excluding a through-hole processed portion, a bubble portion and the like. In addition, when the cross-sectional shape of a groove | channel contains slopes, such as a trapezoid, the numerical value in the deepest place is made into groove depth H1. For example, if the cross-sectional shape of the groove is trapezoidal, the height from the upper base to the lower base is the groove depth H1, and if it is V-shaped or U-shaped, the height from the upper base to the apex of the bottom. Is the groove depth H1. The measurement location only needs to be able to measure the groove width D1, the land width D2, and the groove depth H1, and for example, on the virtual straight line in the direction orthogonal to the extending direction of the plurality of grooves, the intersection of the grooves and the through-hole processed portion It can be a place excluding a bubble part.

[About groove shape]
The shape of the groove 101b is not limited to the stripe groove as described above. 6 to 8 are plan views of the polishing layer 101 showing various shapes of the groove 101b.

  As shown in FIG. 6, the groove 101b may be a concentric groove that is concentric on the polishing surface 101a. In this shape, the land width D2 is a width along a straight line passing through the center of the concentric circular groove. The shape of the polishing layer 101 is not limited to a disk shape as shown in the figure, and may be a rectangular shape or the like. In addition, the shape of the groove 101b may be a concentric arc shape or a wavy line shape, and can be set according to desired polishing conditions. Further, another groove may be superimposed on the groove 101b. For example, it may be a groove shape in which concentric circular grooves and radiation grooves are combined, or a lattice shape in which two types of stripe grooves are combined. Taking as an example a groove in which concentric circular grooves and radial grooves are combined, the fluctuation coefficient of the concentric circular grooves is set to 0.05 or more and 0.30 or less, thereby effectively preventing periodic polishing unevenness derived from the concentric circular grooves. can do. In the case of a groove formed by combining two or more kinds of grooves extending in the same direction, such as a lattice-like groove, the variation coefficient of at least one kind of groove is set to 0.05 or more and 0.30 or less. Although polishing unevenness can be suppressed, it is preferable that periodic polishing unevenness can be effectively prevented by setting the coefficient of variation between 0.05 and 0.30 in any groove.

  Further, as shown in FIGS. 7 and 8, the polishing pad 100 may have a configuration in which a plurality of groove patterns are provided on the polishing surface 101a. The groove pattern can be a stripe groove in which the grooves 101b extend parallel to each other. Further, the groove pattern may be a groove pattern composed of arcuate or wavy grooves 101b.

  Further, a plurality of polishing pads 100 may be combined. In a general polishing process, a plurality of polishing pads may be used in combination in a band shape, a tile shape, a concentric shape, or the like. The polishing pad of the present invention can also be applied to such a method of use. For example, by arranging the grooves so as to be connected, it is possible to correspond to a large polishing apparatus.

  The polishing pad shown in FIGS. 7 and 8 can also be formed by arranging a plurality of polishing pads 100 in a tile shape. As shown in FIG. 7, the plurality of polishing pads 100 in which stripe grooves are formed in a tile shape. It can be arranged to make a pseudo radiation groove. In the drawing, an example in which the square polishing pads 100 are arranged in a tile shape has been described. However, the fan-shaped polishing pads 100 may be arranged in a circular shape.

  Further, as shown in FIG. 8, a plurality of polishing pads 100 in which stripe grooves are formed may be arranged in a tile shape at different angles. The shape of the polishing pad 100 and the arrangement at the time of use can be set according to desired polishing conditions.

  The intervals between the plurality of polishing pads 100 can also be set according to desired polishing conditions. For example, as shown in FIG. 7, the grooves 101b may be separated by lands 101c, or may be in contact with each other between adjacent polishing pads 100 as shown in FIG. When the polishing pads 100 are arranged so as to be in contact with each other, a slight step is generated at the joint portion, which may adversely affect the polishing. The steps may be eliminated by means such as dressing the entire polishing pads 100, the joints may be cut, and the polishing pads 100 may be spaced apart.

  The polishing pad 100 only needs to include a plurality of grooves 101b extending in the same direction having a coefficient of variation of 0.05 or more and 0.30 or less, and the effect of the present invention can be obtained for that region. For example, the groove may be formed so that the variation coefficient is 0.05 or more and 0.30 or less only in a region where polishing accuracy is particularly required. As one embodiment, there is a polishing pad 100 having a groove 101b having a coefficient of variation of 0.05 to 0.30 only in the central region of the polishing surface 101a and no groove in the end region. It is done. As another embodiment, grooves are formed in the central region of the polishing surface 101a so that the variation coefficient is 0.05 or more and 0.30 or less, and the end region is equally spaced (the variation coefficient is 0.00). A polishing pad 100 in which grooves are formed so that Here, if the variation coefficient CV is 0.05 or more and 0.30 or less in a region where the plurality of grooves 101b are preferably 10 or more, more preferably 20 or more, synchronization can be more reliably prevented.

[Groove formation method]
The method for forming the groove 101b in the polishing layer 101 is not particularly limited, but the groove 101b can be formed by cutting the polishing layer 101 with a cutting tool in which blades are arranged in parallel. The width of the groove 101b can be adjusted by the width of the blade and the like, and the variation coefficient can be in the above range. Alternatively, the groove 101b may be formed by embossing.

  A polishing test was performed on the polishing pad according to the example and the polishing pad according to the comparative example using a single-side polishing apparatus under the following conditions. After the polishing test, the polished surface of the object to be polished was irradiated with a high-intensity halogen lamp, and the appearance was visually evaluated for the presence or absence of polishing unevenness with different shadows and textures.

Polishing speed (rotation speed): 30 rpm
Processing pressure: 80 g / cm ²
Polishing slurry: Cerium oxide slurry Polishing pad: Fujibow Atago Co., Ltd. POLYPAS FX-7L
Object to be polished: Glass plate (400mm x 400mm)
Polishing time: 30 min
Number of sheets: 1 sheet x 3 batches

  The following [Table 1] is a table showing the configuration of the polishing pad according to Examples and Comparative Examples. The polishing pad according to the example includes a circular polishing layer having a diameter of 1200 mm having the stripe groove formed of the straight groove shown in the above embodiment, and the coefficient of variation (CV) shown in the above [Equation 1] is 0.059, 0. 105, 0.191 and 0.296 were prepared. A polishing pad according to a comparative example was provided with a polishing layer having a stripe groove formed of a linear groove and having a coefficient of variation of 0.015 and 0.699, respectively, shown in the above [Equation 1]. Specifically, the average groove width is 2.0 mm, the groove depth is 1.0 mm, the land width is 4.0 mm, and a stripe groove including a total of 200 linear grooves obtained by repeating 10 grooves 20 times is shown in Table 1. Thus, the polishing pad which concerns on an Example and a comparative example was created by forming groove width.

  In the polishing pad (CV = 0.015) according to Comparative Example 1, polishing unevenness was confirmed. In addition, in the polishing pad (CV = 0.699) according to Comparative Example 2, polishing unevenness was confirmed. On the other hand, polishing unevenness did not occur in the polishing pad according to the example (CV = 0.599, CV = 0.105, CV = 0.191, CV = 0.296).

  From the above, it can be said that a polishing pad having a coefficient of variation (CV) of 0.05 or more and 0.30 or less can suppress polishing unevenness.

DESCRIPTION OF SYMBOLS 100 ... Polishing pad 101 ... Polishing layer 101a ... Polishing surface 101b ... Groove 101c ... Land 102 ... Adhesive layer 103 ... Cushion layer

Claims (6)

A polishing pad formed with a plurality of grooves extending in the same direction on the polishing surface,
The depth of the plurality of grooves is uniform;
Regarding the width of the plurality of grooves, the coefficient of variation calculated by the following [Formula 1] is 0.05 or more and 0.30 or less,
The land that is the width of the land that is the polishing surface between the plurality of grooves in a direction perpendicular to the extending direction of the grooves is uniform.
Polishing pad.
Coefficient of variation = (standard deviation of groove width) / (average value of groove width) [Formula 1] The polishing pad according to claim 1,
The plurality of grooves are stripe grooves extending parallel to each other on the polishing surface. The polishing pad according to claim 2,
A polishing pad provided with a lattice groove pattern in which two kinds of stripe grooves are superimposed on the polishing surface. The polishing pad according to claim 1,
The plurality of grooves are concentric circular grooves that are concentric on the polishing surface. The polishing pad according to claim 1, wherein a plurality of groove patterns each including a plurality of stripe grooves in which the plurality of grooves extend in parallel with each other are provided on the polishing surface. The polishing pad according to any one of claims 1 to 5, wherein a groove cutting pattern composed of ten or more grooves is repeatedly provided on the polishing surface two or more times. .

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