JP2022056816A - Polishing pad and polishing pad manufacturing method - Google Patents

Abstract

To provide a polishing pad capable of suppressing variations in light transmittance.SOLUTION: A polishing pad 1 has a translucent member 4 and a polishing layer 2, in which the polishing layer has a polishing surface for polishing a polished object, the polishing pad has a through hole 5 penetrating to a surface opposite to the polishing surface from the polishing surface, the translucent member is arranged so that the translucent member exists in the through hole when viewed in a polishing pad thickness direction from the polishing surface side of the polishing pad, and a water contact angle on the surface on the polishing surface side of the translucent member is 80 degrees or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a polishing pad and a method for manufacturing the same, and more particularly to a polishing pad for chemical mechanical polishing (CMP) having a light transmitting region and a method for manufacturing the same. More specifically, the present invention relates to a polishing pad provided with an end point detection window in which the polishing end point can be optically detected.

A chemical mechanical polishing (hereinafter referred to as "CMP") method is used in a semiconductor manufacturing process (particularly, flattening of an interlayer insulating film, metal plug formation, or embedded wiring formation in a multilayer wiring forming process). CMP is a technique for polishing using a slurry in which abrasive grains are dispersed in a state where the surface to be polished of the wafer is pressed against the polished surface of the polishing pad. The polishing pads used for CMP are roughly classified into hard polishing pads and soft polishing pads. The hard polishing pads are a dry molding method in which a curable composition containing a urethane prepolymer is cast into a mold and cured. The wet film forming method in which a urethane resin solution is formed in a coagulation bath and dried is the mainstream. In recent years, low defects and step elimination properties of the object to be polished have been highly required, and the number of cases where a soft polishing pad is used in a finish polishing process or the like is increasing.
In recent years, the number of layers and high definition of semiconductor devices has dramatically increased, and the yield and throughput (yield) of semiconductor devices have been required to be further improved. Sex is required. In order to satisfy these requirements and perform high-precision CMP, it is necessary to determine the polishing end point, and it is necessary to detect the time when the desired surface characteristics and flat state are reached, and the end point is detected by optical measurement. Has been done.

Optical measurement is a method of observing the surface of a wafer through a measurement window provided in a polishing pad. When a window for measurement is provided on the polishing pad for optical measurement, since the polishing pad is generally not transparent, it is necessary to arrange a transparent material different from the polishing pad in the portion to be the window. The light transmittance of this transparent material decreases due to various factors such as scratches on the surface during polishing and dew condensation on the back surface of the transparent material due to the slurry leaking from the gap between the polished region and the transparent material. Therefore, it is difficult to maintain high accuracy in determining the polishing end point from the initial stage of polishing to the final stage of polishing. Further, when a soft polishing pad is used in a finish polishing process or the like, when the polishing pad is pressed against the wafer, the window protrudes to the polishing surface, and the window having no protruding polishing ability hits the wafer, causing polishing scratches. There is a possibility.

As a polishing pad for solving the problem of reduced light transmittance, Patent Document 1 describes that the back surface of the light transmitting region is hydrolyzed so that the slurry can be formed from the seam between the polishing region and the light transmitting region to the light transmitting region. A polishing pad has been proposed that prevents moisture derived from the slurry from condensing on the back surface of the light transmittance region even if it leaks to the back surface side, and prevents a decrease in light transmittance.
Similarly, in Patent Document 2, a polishing pad capable of preventing the slurry from leaking from the gap during polishing by adhering and fixing the light transmitting region to the inner wall of the through hole provided in the polishing substrate with a light curing adhesive. Has been proposed.
According to Patent Document 3, the surface of the light transmitting region on the polished surface side is roughened in advance by sandblasting or the like, so that the light transmittance decreases from the initial stage of polishing to the final stage of polishing. Polishing pads that prevent the occurrence of end point detection errors have been proposed.

Further, as a polishing pad for improving the problem of scratches, Patent Document 4 states that by lowering the window surface from the polishing surface of the polishing layer to have a recess, the window does not hit the wafer and the window surface is damaged. Polishing pads that can prevent or reduce polishing scratches on wafers have been proposed.

Japanese Unexamined Patent Publication No. 2008-221367 Japanese Unexamined Patent Publication No. 2004-343090 Japanese Patent No. 4931133 Japanese Unexamined Patent Publication No. 2014-104521

However, the polishing pads of Patent Documents 1 and 2 both focus on solving the problem of dew condensation caused by leakage to the side surface or the back surface of the translucent member, and are on the surface of the translucent member. We do not pay attention to the variation in light transmittance due to the presence or absence of slurry.
Similarly, with respect to the polishing pad of Patent Document 3, attention is not paid to the variation in light transmittance due to the presence or absence of slurry on the surface of the translucent member. Further, since the polishing pad of Patent Document 3 roughens the window surface, it is difficult to obtain high light transmittance in the first place, and the roughening of the window surface due to the slurry, abrasive grains, dressing, etc. during polishing is different. Therefore, there is also a problem that it is difficult to keep the light transmittance constant at all times.
Since the polishing pad of Patent Document 4 has a recess, most of the slurry that has entered the recess is moved to the side surface of the recess by centrifugal force and then discharged from the groove provided on the polishing surface, and is particularly applied to a soft polishing pad. In that case, the flow of the slurry due to the soft polishing layer is likely to occur, and when the light-transmitting member is irradiated with light, the slurry is likely to be present on the surface of the translucent member and when it is not. However, Cited Document 4 is unaware of this problem and does not mention how to solve it.

The present invention has been made in view of the above, and an object of the present invention is to provide a polishing pad capable of suppressing variations in light transmittance due to the presence of slurry on the surface of a translucent member.

The present inventors have different light transmittances depending on whether the slurry is present or not on the surface of the translucent member, which causes variation in the light transmittance and makes it difficult to determine the polishing end point with high accuracy. The present invention was completed by solving the problem by reducing the water contact angle of the surface of the translucent member on the polished surface side.
That is, the present invention provides the following.

[1] A polishing pad having a translucent member and a polishing layer.
The polishing layer includes a polishing surface for polishing an object to be polished, and the polishing pad has a through hole penetrating from the polishing surface to the opposite surface thereof.
The translucent member is arranged so that the translucent member exists in the through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad, and the translucent member is arranged. The polishing pad having a water contact angle of 80 degrees or less on the surface on the polishing surface side.
[2] The polishing pad according to [1], wherein the uppermost portion of the translucent member is lower than the polishing surface when the polishing surface is the upper surface and the opposite surface is the lower surface.
[3] The polishing pad according to [1] or [2], wherein the water contact angle of the surface of the translucent member opposite to the polishing surface side is more than 80 degrees.
[4] The polishing pad according to any one of [1] to [3], wherein the visible light transmittance when the translucent member is irradiated with light having a wavelength of 380 nm to 780 nm is 60% or more.
[5] The polishing pad according to any one of [1] to [4], wherein the polishing surface has a groove.
[6] The polishing pad according to [5], wherein the groove is an embossed groove.
[7] When the polished surface is the upper surface and the opposite surface is the lower surface, the uppermost portion of the translucent member is at the same position as or lower than the lowermost portion of the groove, [5] or [6]. ] The polishing pad described in.
[8] The polishing pad according to any one of [1] to [7], wherein the shape of the through hole is circular when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad.
[9] When the through hole of the polishing layer is used as the first through hole, the polishing pad further includes another layer having a second through hole having a diameter corresponding to a circle smaller than that of the first through hole.
The other layer is located on the side opposite to the polishing surface of the polishing layer.
When the polishing pad is viewed from the polishing surface side in the thickness direction, the first through hole and the second through hole overlap at least partially.
When viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad, the translucent member is arranged so that the translucent member exists in the first through hole, [1] to The polishing pad according to any one of [8].
[10] A step of preparing a polishing layer and a translucent member having a water contact angle of at least one surface of 80 degrees or less.
The translucent member is arranged so that the translucent member exists in the through hole in the step of providing the through hole in the polishing layer and when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. Step, where the translucent member is arranged such that one surface thereof is on the polished surface side.
The method for manufacturing a polishing pad according to any one of [1] to [9], which comprises.

According to the present invention, it is possible to provide a polishing pad capable of suppressing variations in light transmittance. As a result, the polishing end point can be determined with high accuracy.

FIG. 1 is a perspective view seen in the thickness direction from the polished surface of the polishing pad of one aspect of the present invention. FIG. 2 is a schematic cross-sectional view (cut end face) in the thickness direction of the polishing pad according to one aspect of the present invention. FIG. 3 is a schematic cross-sectional view (cut end face) in the thickness direction of the polishing pad according to one aspect of the present invention. FIG. 4 is a schematic cross-sectional view (cut end face) in the thickness direction of the polishing pad according to one aspect of the present invention. FIG. 5 is a schematic cross-sectional view (cut end face) in the thickness direction of the polishing pad according to one aspect of the present invention. FIG. 6 is a schematic cross-sectional view (cut end face) in the thickness direction of the polishing pad according to one aspect of the present invention.

Hereinafter, embodiments for carrying out the present invention will be described.

<< Polishing Pad >>
The polishing pad of the present invention is a polishing pad having a translucent member and a polishing layer, the polishing layer includes a polishing surface for polishing an object to be polished, and the polishing pad is the opposite of the polishing surface. The translucent member has a through hole penetrating to the surface, and the translucent member exists in the through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. The polishing pad is arranged so as to be used, and the water contact angle of the surface of the translucent member on the polishing surface side is 80 degrees or less.

In the present specification and claims, the polishing layer is a layer having a surface (polished surface) that comes into contact with the object to be polished and is polished when the object to be polished such as a semiconductor device is polished. The object to be polished is not particularly limited, and examples thereof include a product substrate including a plurality of memory dies or processor dies, a test substrate, a bare substrate, and a gate substrate. The substrate can be from various stages of integrated circuit manufacturing, for example, the substrate can be a bare wafer, or it can be one or more deposition layers and / or pattern forming layers.

<Translucent member>
The polishing pad of the present invention has a translucent member, that is, a window member. By irradiating the object to be polished with light through the translucent member, it is possible to detect the time when the object to be polished reaches the desired surface characteristics or flat state. A visible light (white light) laser, lamp, or the like is used for optical end point detection.
The translucent member is arranged so that the translucent member exists in the through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. Here, "they are arranged so that the translucent member exists in the through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad" means that the thickness is from the polishing surface of the polishing pad. It is intended that the translucent member is arranged so that the translucent member can be confirmed when the inside of the through hole is viewed in the vertical direction. (1) The translucent member is a polishing layer as shown in FIGS. When it is arranged so as to be in contact with (or adhere to) the side surface (side wall) of the through hole provided in (2), it corresponds to the circle of the through hole of the polishing layer in the lower layer of the polishing layer as shown in FIG. When another layer having a through hole having a diameter equivalent to a circle smaller than the diameter is provided, and the translucent member is arranged on the exposed portion 7 caused by the difference in size between the through hole of the polishing layer and the through hole of the other layer. Or (3) when the translucent member is sandwiched between the polishing layer and another layer as shown in FIG. 5, and a part of the translucent member is arranged so as to be exposed in the through hole. (4) As shown in FIG. 6, through holes are provided in both the polishing layer and the other layer, and the translucent member is arranged so as to be in contact with (or adhere to) the side surface of either or both of the through holes. It is a concept including the case where there is. Among these, (1), (2) or (4) is preferable, (1) or (2) is more preferable, and (2) is even more preferable.

The translucent member is preferably a transparent resin member. The transparent resin member is not particularly limited as long as it has transparency enough to transmit light, and for example, heat of a polyurethane resin, a polyester resin, a phenol resin, a urea resin, a melamine resin, an epoxy resin, an acrylic resin, or the like. Curable resin, polyurethane resin, polyester resin, polyamide resin, cellulose resin, acrylic resin, polycarbonate resin, halogen resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene resin, and olefin resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.) Thermoplastic resins such as polyethylene and polypropylene), rubbers such as butadiene rubber and isoprene rubber, photocurable resins that are cured by light such as ultraviolet rays and electron beams, and photosensitive resins can be used. Among these, acrylic resin, polyurethane resin, polyester resin, and polystyrene resin are preferable, and acrylic resin is more preferable.

The surface of the translucent member on the polished surface side is preferably hydrophilized. The translucent member may be hydrophilized not only on the surface on the polished surface side but also on the surface (back surface) and the side surface opposite to the polished surface, but it is costly to hydrophilize the back surface and the side surface as well. However, since the hydrophilization of the back surface and the side surface is not related to the effect of the present invention, it is preferable that only the surface surface on the polished surface side is hydrophilized. By hydrophilizing the surface on the polished surface side, it becomes easy to obtain a translucent member having a water contact angle of 80 degrees or less on the surface on the polished surface side.
Examples of the means for hydrophilization include physicochemical treatment such as plasma treatment and ultraviolet irradiation treatment, mechanical treatment such as roll blast treatment and embossing treatment, and chemical treatment such as chemical treatment and surface grafting treatment. Be done. Among these, plasma treatment or roll blast treatment is preferable, and plasma treatment is more preferable.
Plasma processing is a process of hitting the surface of a material with a plasma beam emitted from a rod called an electrode using a high-voltage power supply. On the surface of the material, ions and electrons emitted by the beam break the chemical bonds of the molecules on the resin surface, and depending on the type of resin, hydrophilic functional groups (OH (hydroxyl group), CO (carbonyl group), COOH (carboxyl group) Group) etc.) are generated.
The roll blasting process is a process of rotating a roll with abrasive grains at high speed to modify the surface.

In the polishing pad of the present invention, when the polishing surface is the upper surface and the opposite surface is the lower surface, the uppermost portion of the translucent member may be at the same height as the polishing surface or lower than the polishing surface. It is preferably lower than the polished surface (Fig. 2). Since the uppermost portion of the translucent member is lower than the polished surface, it is possible to prevent the occurrence of polishing scratches due to the translucent member that is harder than the polishing layer. Further, when the uppermost portion of the translucent member is lower than the polished surface, the slurry enters the recess surrounded by the translucent member and the side surface of the through hole, and most of the slurry moves to the side surface of the through hole by centrifugal force to form a groove. Since it is discharged through the light-transmitting member, a small amount of slurry may or may not remain on the surface of the translucent member. However, when a conventional polishing pad is used, the light transmittance differs between the case where a small amount of slurry remains in the translucent member and the case where it does not remain, so that the polishing end point is determined with high accuracy. It's difficult. On the other hand, the polishing pad of the present invention has a hydrophilic surface of the translucent member, which makes it more compatible with the slurry, and even if a small amount of slurry is present, it spreads evenly on the window surface. The fluctuation of the light transmittance is reduced from the initial stage to the final stage of polishing, and even if the uppermost portion of the translucent member is located lower than the polishing surface, the uppermost portion 4'of the translucent member is particularly the lowermost portion 8 of the groove. Even if it is at the same position as or lower than that, the polishing end point can be determined with high accuracy.

(Water contact angle)
The polishing pad of the present invention has a water contact angle of 80 degrees or less on the surface of the translucent member on the polishing surface side. The water contact angle is preferably 5 to 80 degrees, more preferably 5 to 50 degrees, even more preferably 5 to 30 degrees, and even more preferably 5 to 20 degrees. When the water contact angle is within the above range, it is possible to suppress the variation in the light transmittance due to the presence or absence of the slurry on the surface of the translucent member. This makes it possible to determine the polishing end point with higher accuracy.
Window members used in conventional polishing pads generally have a water contact angle of more than 80 degrees. When a window having a hydrophilicity of 80 degrees or less is used, the slurry may swell and deform the window, peel off from the polished area, or cause slurry leakage. Therefore, the window member is preferably hydrophobic with a water contact angle of more than 80 degrees, and in the present invention, it is preferable to hydrophilize only the surface on the polished surface side so that the water contact angle is 80 degrees or less. In the present invention, there is no particular limitation on the method of setting the water contact angle of the surface of the translucent member on the polished surface side to 80 degrees or less, but the surface on the polished surface side is hydrophilized and the water on the surface on the polished surface side is treated. It is preferable to use one having a contact angle of 80 degrees or less. Examples of the hydrophilization treatment means include the above.
As the translucent member, the water contact angle on the surface on the polished surface side may be 80 degrees or less, and the water contact angle on the back surface or the side surface is not particularly limited. Therefore, the water contact angle on the back surface and the side surface may be more than 80 degrees. That is, the back surface and the side surface of the translucent member may not be hydrophilized.

(Transmittance)
The polishing pad of the present invention has a visible light transmittance (sometimes referred to simply as light transmittance in the present specification) when the translucent member is irradiated with light having a wavelength of 380 nm to 780 nm, which is 60% or more. It is preferably 62% or more, more preferably 65% or more, even more preferably 70% or more, further preferably 75% or more, and even more preferably 80% or more. Is even more preferable, and 85% or more is even more preferable.
In the polishing pad of the present invention, the light transmittance when water is adhered to the surface of the translucent member is preferably 60% or more, more preferably 62% or more, and more preferably 65% or more. It is even more preferably 70% or more, even more preferably 75% or more, and even more preferably 80% or more.
In the polishing pad of the present invention, the light transmittance when water is not adhered to the surface of the translucent member is preferably 60% or more, more preferably 62% or more, and more preferably 65% or more. It is even more preferably 70% or more, even more preferably 75% or more, even more preferably 80% or more, and even more preferably 85% or more.
In the polishing pad of the present invention, the difference between the light transmittance when water is not attached to the surface of the translucent member and the light transmittance when water is attached to the surface of the translucent member is It is preferably within 30%, more preferably within 20%, even more preferably within 15%, even more preferably within 10%, and even more preferably within 8%. It is preferably within 6%, even more preferably within 5%. When the difference in light transmittance is within the above range, the difference in light transmittance is less likely to occur between the case where the slurry is present on the surface of the translucent member and the case where there is no slurry, and the determination of the polishing end point is made with high accuracy. Can be done.
The light transmittance can be measured by measuring a transmission spectrum having a wavelength of 300 to 1000 nm with a spectrophotometer and determining it as the visible light transmittance (%) of the Japanese Industrial Standards (JIS A5759: 2008). That is, the transmittance of each wavelength in the range of 380 to 780 nm is measured, and the weight obtained from the spectral distribution of CIE (International Lighting Commission) daylight D65, the wavelength distribution of CIE bright adaptation standard relative visibility, and the wavelength interval. It is the transmittance obtained by multiplying the transmittance at each wavelength by the weight coefficient and averaging the valence coefficient.
Further, the measurement of the light transmittance when water is adhered to the surface of the translucent member is 0.01 for a translucent member cut out to a size of 9 mm × 50 mm by a spray. (Approximately 0.03 mL) of water was adhered to the entire surface of the translucent member on the polished surface side, and then the translucent member was placed perpendicular to the ground and allowed to stand for 60 seconds to drain water. This can be done using a light member.

(Through hole)
The through hole is a hole that penetrates from the polishing surface to the opposite surface when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. The through hole preferably penetrates the polishing layer parallel to the thickness direction or perpendicular to the polishing surface.
One through hole may be provided in the polishing layer, or two or more through holes that are separated from each other and independent of each other may be provided.
Examples of the shape of the through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad or the shape of the through hole on the polishing surface include a circle, an ellipse, a triangle, a quadrangle, a hexagon, and an octagon. .. Alternatively, the same or different shapes may be a shape in which the same or different shapes partially overlap each other. Among these, a circular shape that does not form a corner where polishing debris easily collects is particularly preferable.

(Diameter equivalent to a circle)
In the present specification and claims, the circle-equivalent diameter is the diameter of a perfect circle corresponding to the area of the figure to be measured.
The circle-equivalent diameter of the through hole is the circle-equivalent diameter of the through hole when viewed from the polishing surface side of the polishing pad in the polishing pad thickness direction, and when viewed from the polishing surface side of the polishing pad in the polishing pad thickness direction. When the shape of the through hole is circular, it corresponds to the diameter.
The equivalent circle diameter of the through hole is not particularly limited, but is preferably 5 to 40 mm, more preferably 5 to 30 mm, and even more preferably 10 to 28 mm.
The area of the through holes on the polished surface is preferably 0.003 to 0.5%, more preferably 0.004 to 0.4%, based on the total area of the polished surface. Even more preferably, it is 003 to 0.3%.

(Structure of polishing layer)
The resin constituting the polishing layer includes polyurethane resins such as polyurethane and polyurethane polyurea; acrylic resins such as polyacrylate and polyacrylonitrile; vinyl resins such as polyvinyl chloride, polyvinyl acetate and polyvinylidene fluoride; polysulfone and poly. Examples thereof include polysulfone-based resins such as ether sulfone; acylated cellulose-based resins such as acetylated cellulose and butyrylated cellulose; polyamide-based resins; and polystyrene-based resins. Among these, polyurethane resin is more preferable in consideration of compression characteristics and flexibility.
The polishing layer may be composed of one kind of resin or may be made of two or more kinds of resins.
Further, the polishing layer preferably has open cells. The open bubbles referred to here refer to foaming having a space in which adjacent bubbles are connected to each other by communication holes. Specifically, a resin by a wet film forming method, a dry molding, or a foam by injection molding may be used. It is preferably a wet film forming method, and good bending and stretching motion can be expected.
In the present specification, the resin formed by the wet film forming method means a resin (preferably polyurethane resin) formed by the wet film forming method. The wet film forming method is a method in which a resin to be formed is dissolved in an organic solvent, the resin solution is applied to a sheet-shaped substrate, and then the resin is passed through a coagulating liquid to coagulate the resin. The wet-formed resin generally has a plurality of teardrop-shaped bubbles (a shape having anisotropy and a structure having a large diameter from the polished surface to the bottom of the polishing pad). Therefore, the wet-formed resin can be rephrased as a resin having a plurality of tear-shaped bubbles. The plurality of tear-shaped bubbles are preferably in the form of open cells.

(groove)
The polishing pad of the present invention preferably has a groove on the polished surface of the polishing layer. The groove does not penetrate the polishing layer and can be distinguished from the through hole.
Examples of the groove include an embossed groove obtained by embossing the polished surface and a cutting groove obtained by cutting with a cutting tool. Of these, the embossed groove is preferable. By providing a groove such as an embossed groove, burrs are less likely to appear on the polished surface, and a polishing pad suitable for finish polishing can be obtained.
The depth of the groove is not particularly limited as long as it is smaller than the thickness of the polishing layer, but is preferably 50 to 90%, more preferably 60 to 80% of the thickness of the polishing layer. When the groove disappears due to the polishing of the object to be polished, the flow discharge property of the polishing slurry is lost and the polishing performance is deteriorated. Therefore, the polishing pad has reached the end of its life. Therefore, it is preferable that the groove depth is deep. On the other hand, in order to increase the groove depth of the embossed groove, it is necessary to increase the processing pressure or the processing temperature, which causes deformation of the base material (PET) on the back surface of the polishing layer and deterioration of the surface of the polishing layer. there is a possibility. When the groove depth is within the above range, these problems are unlikely to occur.
The cross-sectional shape of the groove is not particularly limited, and may be an arc shape, a U shape, a V shape, a rectangular shape, a trapezoidal shape, or another polygonal shape, and a combination of these two or more shapes. It may be. Further, the number and shape of the grooves are not particularly limited, and the number and shape of the grooves may be appropriately adjusted according to the purpose of use of the polishing pad and the like. Examples of the shape include a grid shape, a radial shape, a concentric circle shape, a honeycomb shape, and the like, and these may be combined.
Further, in the polishing pad of the present invention, the surface of the polishing layer may be opened by grinding (buffing) or may be sliced.

In the polishing pad of the present invention, when the polishing surface is the upper surface and the opposite surface is the lower surface, even if the uppermost portion 4'of the translucent member is higher than the lowermost portion 8'of the groove, the lowermost portion 8' It may be in the same position as or lower than the bottom 8', but it is preferably in the same position as or lower than the bottom 8'of the groove, and the translucent member. It is more preferred that the top 4'is lower than the bottom 8'of the groove. Polishing pads generally end their life when polished to the point where the grooves on the polished surface are gone, but the grooves disappear when the top of the translucent member is at or below the bottom of the groove. Up to can use polishing pads.
Further, in the conventional polishing pad, if the uppermost portion 4'of the translucent member is located at the same position as or lower than the lowermost portion 8'of the groove, the slurry and the polishing debris are less likely to be discharged from the groove. , There may be a problem that the light transmittance decreases with time. On the other hand, in the polishing pad of one aspect of the present invention (polishing pad of FIG. 4), the slurry and polishing debris that have entered the recess in the first through hole are placed on the side surface of the first through hole by the centrifugal force during the polishing process. Since it moves and becomes difficult to see from the second through hole having a small equivalent circle diameter, it is possible to prevent a decrease in light transmittance. Furthermore, even if only a small amount of slurry is present on the surface of the translucent member after most of the slurry has moved to the side surface of the recess, the light transmittance is unlikely to decrease due to the slurry, so that stable light detection is possible. Is possible.

(Shore A hardness)
In the present specification, the shore A hardness means a value measured according to the Japanese Industrial Standards (JIS K7311).
In the polishing pad of the present invention, the shore A hardness of the polishing layer is preferably 5 to 70 degrees (°), more preferably 8 to 65 degrees. When the shore A hardness of the polishing layer is within the above range, excessive contact of the polishing debris with the object to be polished is suppressed, so that scratches are less likely to occur.
Further, in the polishing pad of the present invention, the polishing layer is preferably softer than the translucent member, and more preferably the shore A hardness is lower than that of the translucent member.

(Compression modulus and compressive elastic modulus)
In the present specification, the compressibility is an index of softness, and the compressive elastic modulus is an index of ease of return to compressive deformation.
The compressibility and compressive elastic modulus can be determined by using a shopper type thickness measuring instrument (pressurized surface: circular with a diameter of 1 cm) in accordance with Japanese Industrial Standards (JIS L1021). Specifically, it is as follows.
The thickness t ₀ after the initial load is applied for 30 seconds from the unloaded state is measured, and then the thickness t ₁ after the final load is applied for 5 minutes from the state of the thickness t ₀ is measured. Next, all the loads are removed from the state of the thickness t ₁ , and after leaving for 5 minutes (with no load), the initial load is applied again for 30 seconds, and then the thickness t _0'is measured.
The compression rate can be calculated by the formula of compression rate (%) = 100 × (t ₀ − t ₁ ) / t ₀ (note that the initial load is 100 g / cm ² and the final load is 1120 g / cm ² ). ).
The compressive elastic modulus can be calculated by the formula of compressive elastic modulus (%) = 100 × (t _0' -t ₁ ) / (t ₀ -t ₁ ) (the initial load is 100 g / cm ² and the final load is 100 g / cm 2). The load is 1120 g / cm ² ).
The compressibility of the polishing layer is preferably 1 to 60%, more preferably 3 to 50%. The compressive elastic modulus of the polishing layer is preferably 50 to 100%, more preferably 60 to 98%. When the compression modulus and the compressive elastic modulus are within the above ranges, the polishing layer is compressed when the object to be polished passes over the through hole, and the polishing property is excellent in recovery after being pushed by the object to be polished. The bending and stretching motion of the layer creates a flow of slurry inside the through hole, the slurry circulates without staying in the through hole, and the polishing debris that has entered the through hole together with the slurry is discharged to the outside of the through hole by the operation of compression and recovery. It will be easier. This makes it easier to prevent the polishing debris from accumulating in the through holes.

(Thickness)
The thickness can be determined by using a shopper type thickness measuring instrument (pressurized surface: circular with a diameter of 1 cm) in accordance with Japanese Industrial Standards (JIS K6505). Specifically, it is as follows.
Prepare a sample of 10 cm square in length and width. Place the sample on the measuring instrument with the surface facing up. A pressurized surface with a load of 100 g / cm ² is placed on the sample, and the thickness after 5 seconds is measured. Measure 5 points per sheet and use the average value as the thickness. If a 10 cm square sample cannot be obtained, the average of 5 locations is used.
The thickness of the polishing layer is not particularly limited, but is preferably 0.5 to 2 mm, and even more preferably 0.75 to 1.55 mm.

(Layer other than the polishing layer)
The polishing pad of the present invention may have a layer (other layer) other than the polishing layer. The other layer may be one layer or two or more layers on the surface of the polishing layer opposite to the polishing surface. The other layer has through holes like the polished layer.
Further, the shapes of the through holes of the polishing layer and the through holes of other layers may be the same or different, but when the polishing pad is viewed from the polishing surface side in the thickness direction, the polishing layer may be different. It is preferable that the through-holes of the above and the through-holes of other layers are at least partially overlapped with each other. As a result, when the light is applied to the translucent member, the light is transmitted through the translucent member.

As one aspect of the present invention, when the polishing pad has another layer, the other having a through hole (second through hole) having a diameter equivalent to a circle smaller than the through hole (first through hole) existing in the polishing layer. It may have a layer (Fig. 4). The other layer is a layer located on the side opposite to the polishing surface of the polishing layer.
In the polishing pad of this aspect, it is preferable that the first through hole and the second through hole are at least partially overlapped when viewed from the polishing surface side in the thickness direction. Further, it is preferable that the translucent member is arranged so that the translucent member exists in the first through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad.

In the polishing pad of this embodiment, when viewed in the thickness direction from the polishing surface side of the polishing pad, the outer peripheral portion of the first through hole 5 covers a part or all of the outer peripheral portion of the second through hole 6. It is preferable that the first through hole 5 is provided so that the outer peripheral portion thereof covers the entire outer peripheral portion of the second through hole 6, and the first through hole 5 and the second through hole 5 are provided. It is even more preferable that both the holes 6 have a cylindrical shape, and the central axis of the cylinder of the first through hole 5 and the central axis of the cylinder of the second through hole 6 coincide with each other (see FIG. 4).

Here, when the first through hole and the second through hole are at least partially overlapped when viewed in the thickness direction from the polished surface side, the first through hole is when viewed in the thickness direction from the polished surface side. 1 It means that the opening position of the through hole and the opening position of the second through hole are at least partially coincident with each other. The polishing pad of this embodiment has the same as the first through hole because the opening position of the first through hole and the opening position of the second through hole are at least partially coincident when viewed in the thickness direction. The second through hole is connected in the thickness direction of the polishing pad. When the positions of the first through hole and the second through hole are at least partially overlapped when viewed from the polished surface side in the thickness direction, the translucent member provided in the first through hole is interposed. Light can be transmitted from the second through-hole side to the first through-hole side, and the surface state of the object to be polished during the polishing process can be optically detected.

In the polishing pad of this embodiment, the translucent member is arranged so that the translucent member 4 exists in the first through hole 5 when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. Is preferable. Further, it is preferable that the translucent member 4 is provided in the first through hole 5.
Here, when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad, it is said that the translucent member is arranged so that the translucent member exists in the first through hole. It means that the translucent member can be confirmed when the inside of the first through hole is viewed from the polishing surface side of the pad in the thickness direction of the polishing pad.
Further, the first through hole 5 is a part of the other layer 3 (hereinafter referred to as an exposed portion 7 of the other layer) and the second through hole when the polishing pad 1 is viewed from the polishing surface side in the thickness direction. It is preferable to arrange so that at least a part of 6 is exposed. Thereby, the translucent member 4 can be arranged in the first through hole 5 and on the second through hole 6 and the exposed portion 7 of the other layer 3. Preferably, the first through hole 5 is arranged so that a part of the other layer 3 and all of the second through hole 6 are exposed when the first through hole 5 is viewed from the polished surface side. .. Further, it is preferable that the translucent member 4 is provided in the first through hole 5 and is adhered to the exposed portion 7 of the other layer 3.
Referring to FIG. 4, in the thickness direction cross section of the polishing pad 1 of the present invention, the first through hole 5 is provided in the second through hole 6 and the polishing layer 2 on the exposed portion 7. It should be noted that a further layer may be provided between the other layer 3 provided with the exposed portion 7 and the polishing layer 2. In this case, the through holes existing in the further layer may be the polishing layer 2. It has the same cross-sectional shape as the through hole (first through hole) (cross-sectional shape in the horizontal direction with the polished surface), and completely overlaps with the first through hole 5 when viewed in the thickness direction from the polished surface. Is preferable. It is preferable that the translucent member 4 is arranged on the second through hole 6 and the exposed portion 7 and inside the first through hole 5 of the polishing layer 2 and the through hole of another layer.

One second through hole may be provided in the other layer, or two or more through holes that are separated from each other and independent of each other may be provided. It is preferable that the number of first through holes and the number of second through holes are equal. When a plurality of first through holes and a plurality of second through holes are provided, each first through hole shall be provided on each second through hole provided in another layer and its exposed portion. Is preferable.

The second through hole preferably penetrates the other layer parallel to the thickness direction or perpendicular to the polished surface.
The polishing pad of the present invention has a different shape even if the cross-sectional shape of the first through hole and the cross-sectional shape of the second through hole when cut perpendicular to the thickness direction have the same shape. It may have the same shape, but it is preferable.
The shape of the second through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad, the cross-sectional shape of the second through hole when cut perpendicular to the thickness direction of the polishing pad, and / or Examples of the shape of the second through hole on the surface of the other layer include a circle, an ellipse, a triangle, a quadrangle, a hexagon, an octagon, and a shape in which these shapes are combined. Alternatively, the same or different shapes may be a shape in which the same or different shapes partially overlap each other. Of these, a circular shape is particularly preferable.

(Diameter equivalent to a circle)
Within the scope of the present specification and patent claims, the circle-equivalent diameter of the second through hole is the circle-equivalent diameter of the second through hole when viewed from the polishing surface side of the polishing pad in the polishing pad thickness direction, and is the polishing pad. When the shape of the second through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad is circular, it corresponds to the diameter.
It is preferable that the equivalent circle diameter of the first through hole is larger than the equivalent circle diameter of the second through hole. As long as the equivalent circle diameter of the first through hole is larger than the equivalent circle diameter of the second through hole, the equivalent circle diameter of the second through hole is not particularly limited, but the equivalent circle diameter of the second through hole is preferably 1 to 20 mm. 2 to 18 mm is more preferable, and 5 to 15 mm is even more preferable. Further, the difference between the equivalent circle diameter of the first through hole and the equivalent circle diameter of the second through hole is not particularly limited, but the equivalent circle diameter of the first through hole is 5 to 30 mm from the equivalent circle diameter of the second through hole. Larger is preferable, 6 to 25 mm larger is more preferable, and 7 to 20 mm larger is even more preferable.
Further, when viewed in the thickness direction from the polishing surface side of the polishing pad, the outer peripheral portion of the first through hole is provided so as to cover the entire outer peripheral portion of the second through hole, and the first through hole is provided. The equivalent circle diameter is preferably 5 to 30 mm larger than the equivalent circle diameter of the second through hole, more preferably 6 to 25 mm larger, even more preferably 7 to 20 mm larger, and even more preferably 8 to 20 mm larger. Preferably, it is 9 to 20 mm larger, even more preferably 10 to 20 mm larger.
Further, when viewed in the thickness direction from the polishing surface side of the polishing pad, the outer peripheral portion of the first through hole is provided so as to cover the entire outer peripheral portion of the second through hole, and the first through hole is provided. The equivalent circle diameter of the second through hole is preferably 1.5 to 4 times, more preferably 2 to 4 times, and even more preferably 2.5 to 3 times the equivalent circle diameter of the second through hole. preferable.

Further, when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad, the shortest distance between the outer peripheral portion of the second through hole and the outer peripheral portion of the first through hole (that is, the outer peripheral portion of the second through hole). The shortest distance between an arbitrary point and an arbitrary point on the outer peripheral portion of the first through hole) is preferably larger than 0, the shortest distance is more preferably 2 to 15 mm, and the shortest distance is 3 to 12 mm. It is even more preferable that the distance is 4 to 10 mm.
If the difference in size between the first through hole and the second through hole is within the above range, the slurry and polishing debris that have entered the recess in the first through hole will be removed from the first through hole by the centrifugal force during the polishing process. Since it moves to the outer peripheral side and becomes difficult to see from the second through hole having a small diameter equivalent to a circle, it is possible to prevent the optical path from being blocked by the polishing debris when the translucent member is irradiated with light. Therefore, excellent light transmittance can be maintained, and stable end point detection signal intensity can be obtained during polishing. Further, since the area of the exposed portion is sufficiently large, the adhesive strength between the translucent member and another layer can be maintained, and the translucent member can be prevented from peeling off.
Further, even if most of the slurry moves to the side surface of the recess and only a small amount of slurry is present on the surface of the translucent member, the polishing pad of the present invention has a variation in light transmittance depending on the presence or absence of the slurry. Since it is difficult, stable light detection is possible.

Further, as another aspect, when the polishing pad of the present invention contains another layer, a sheet-shaped translucent member is sandwiched between the polishing layer and the other layer, and a part of the translucent member is a through hole. It may be arranged so as to be exposed inside (FIG. 5). At this time, when viewed in the thickness direction from the polishing surface side, the through hole existing in the other layer (second through hole) and the through hole existing in the polishing layer (first through hole) are at least partially. It is preferable that they overlap, and it is more preferable that they completely overlap. At this time, the polishing layer preferably has open cells having communication holes.
When the polishing layer has open cells having communication holes, open bubbles also open on the side surface of the first through hole provided in the polishing layer, so that a part of the open cells communicates with the polishing surface or the groove region. As a result, the slurry and polishing debris that have entered the first through hole during polishing move to the side surface of the first through hole due to the centrifugal force generated during the polishing process, and pass through the open air bubbles having the communication holes to the polishing surface and the groove. Since it is discharged to the region, it is possible to prevent a decrease in the light transmittance over time due to the accumulation of polishing debris in the first through hole, which leads to a longer life of the polishing pad.

In addition, as another aspect, when the polishing pad of the present invention contains another layer, through holes are provided in both the polishing layer and the other layer provided under the polishing layer, and the side surfaces of either or both of the through holes ( The translucent member may be arranged so as to be in contact with (or adhere to) the side surface of another layer (FIG. 6). At this time, when viewed in the thickness direction from the polishing surface side, the through hole existing in the other layer (second through hole) and the through hole existing in the polishing layer (first through hole) are at least partially. It is preferable that they overlap, and it is more preferable that they completely overlap. The translucent member is preferably adhered to the side surface of the second through hole. Further, it is preferable that the translucent member does not exist in the first through hole.
Since the translucent member is adhered to the side surface of the second through hole of the other layer, the thickness of the polishing layer that can be used for polishing is maximized, and even if the polishing surface is scraped by wear during dressing or polishing. The translucent member does not protrude from the polished surface, and the occurrence of scratches can be reduced. In general, the softer the polishing layer of the polishing pad, the higher the risk that the polishing pad will sink due to the polishing pad being pressed against the wafer and the translucent member will protrude, and the polishing pad with the protrusion will be covered. It cannot be used for polishing polished materials. Since the polishing pad of this aspect can prevent the translucent member from protruding, the life of the polishing pad can be extended. Further, if the translucent member is not bonded to the polishing layer but is arranged so as to adhere to the side surface of the second through hole, the polishing debris that has entered the first through hole is easily discharged to the groove or the polishing surface. Even if the layer is provided with an expansion / contraction mechanism, distortion is unlikely to occur at the bonded portion of the translucent member, whereby peeling of the translucent member can be suppressed.

(Structure of other layers)
Materials constituting the other layer include polyethylene (PE), polypropylene (PP), polyethylene-based sheets such as ethylene / propylene copolymer, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN). ) Etc., polyester-based sheets, vinyl chloride-based sheets, vinyl acetate-based sheets, polyimide-based sheets, polyamide-based sheets, fluororesin-based sheets, resin-impregnated non-woven fabrics, non-woven fabrics, woven fabrics, and the like. Further, the other layer is preferably a non-porous sheet in which the slurry does not penetrate into the inside. Among these, it is a non-porous sheet in which the slurry does not penetrate inside, and the other layers are polyester from the viewpoint of physical properties (for example, dimensional stability, thickness accuracy, processability, tensile strength), economy, and the like. Based sheets are more preferable, and among them, polyethylene terephthalate (hereinafter abbreviated as PET) sheets are particularly preferable.
As a method of bonding the other layer to the polishing layer or a method of bonding the other layer to another layer, for example, a sheet such as a PET sheet coated with an adhesive on one side or both sides is used as another layer. The other layer can be adhered to the polishing layer or another layer via this pressure-sensitive adhesive. A sheet such as a PET sheet to which no adhesive is applied is prepared as another layer, and a polishing layer or another layer and an adhesive are prepared separately from this, and the other layer is prepared via the adhesive. Can also be adhered to the polishing layer or another layer.

(advantage)
In the polishing pad of the present invention, the water contact angle of the surface of the translucent member on the polishing surface side is 80 degrees or less, so that the presence or absence of slurry on the surface of the translucent member on the polishing surface side determines the light transmittance. Has little effect. As a result, the polishing end point can be determined with high accuracy.
Further, in the polishing pad of the present invention, when the polishing surface is the upper surface and the opposite surface is the lower surface, the translucent member is lower than the polishing surface even if the translucent member is at the same height as the polishing surface. The effect is exhibited even if it is in a position, but it is more effective especially when the translucent member is in a position lower than the polished surface. That is, when the translucent member is located at a position lower than the polished surface, there is a recess (for example, a columnar recess) surrounded by the surface of the translucent member and the side surface of the through hole. Slurry enters. Most of the slurry that has entered the recess moves to the side surface under the influence of centrifugal force and is discharged through the embossed groove, so the slurry exists in the region where the laser light on the surface of the translucent member is transmitted over time. There may be a timing at which the slurry flows into the recess (a timing at which a large amount of slurry flows into the recess, a timing at which the slurry cannot be discharged, etc.) and a timing at which the slurry does not exist. When the water repellency of the surface of the translucent member is high, the slurry adheres in the form of water droplets or streaks on the window surface without being familiar, so that the parallel light transmittance when the slurry does not exist in the region through which the laser light is transmitted. On the other hand, the parallel light transmittance when the slurry is present is significantly reduced due to the scattering of light by the water droplet-like slurry, and the light transmittance during the polishing process tends to vary. In the polishing pad of the present invention, by lowering (hydrophilizing) the water contact angle of the surface of the translucent member on the polishing surface side, the slurry can be wetted and spread on the window surface without forming water droplets. It is possible to suppress the scattering of light and reduce the fluctuation of the light transmittance depending on whether the slurry is attached or not, and thereby it is possible to suppress the variation in the light transmittance during the polishing process.
The polishing pad of the present invention can be manufactured, for example, by the following method.

<< Manufacturing method of polishing pad >>
In the manufacturing method of the present invention, a step of preparing a polishing layer and a translucent member having a water contact angle of at least one surface of 80 degrees or less, a step of providing a through hole in the polishing layer, and the translucent member are described above. A method for manufacturing a polishing pad, which comprises a step of arranging the translucent member so as to be visible in the through hole (here, the one surface of the translucent member is arranged so as to be on the polishing surface side). ..
Each process will be described.

<1. Step of preparing a polishing layer and a translucent member having a water contact angle of at least one surface of 80 degrees or less>
In this step, a polishing layer and a translucent member having a water contact angle of at least one surface of 80 degrees or less are prepared.
As the polishing layer and the translucent member, the above-mentioned ones can be used respectively. As the polishing layer and the translucent member, commercially available ones may be used or manufactured ones may be used. Commercially available translucent members include "Diafoil T910E" and "Diafoil T600E" manufactured by Mitsubishi Chemical Co., Ltd., "Cosmo Shine A4300", "Cosmo Shine A2330" and "Cosmo Shine TA017" manufactured by Toyo Spinning Co., Ltd. , "Cosmo Shine TA015", "Cosmo Shine TA042", "Cosmo Shine TA044", "Cosmo Shine TA048", "Soft Shine TA009", "Acryplen HBXN47" made by Mitsubishi Chemical Co., Ltd. HBS010 ", Teijin Kasei Co., Ltd." Panlight Film PC-2151 ", Kaneka Co., Ltd." Sanduren SD009 "," Sanduren SD010 ", Sumitomo Chemical Co., Ltd." C000 "made of polycarbonate resin, Teijin Kasei Co., Ltd." Upiron H-3000 ", Sumitomo Chemical Co., Ltd." C001 "made of acrylic resin / polycarbonate resin, Sumitomo Chemical Co., Ltd." S000 "," S001G "," S014G "made of acrylic resin, Mitsubishi Chemical Co., Ltd." Acryplen ""HBS006","ZeonoaZF14" made by Nippon Zeon Co., Ltd., "Zeonoa ZF16" made of alicyclic polyolefin resin, "Arton film" manufactured by JSR Corporation, etc. can be obtained as commercial products. When the polishing layer is manufactured, for example, it can be manufactured by forming a wet film of a polyurethane resin with reference to Japanese Patent No. 5421635 and Japanese Patent No. 5844189 and laminating it with a flexible sheet made of PET resin.

The production method of the present invention may further include a step of hydrophilizing at least one surface (preferably only the surface on the polished surface side) of the translucent member. This makes it possible to obtain a translucent member having a water contact angle of 80 degrees or less on the surface on the polished surface side. Examples of the method for hydrophilization treatment include the above.

<2. Process of providing through holes in the polishing layer>
In this step, a through hole is provided in the polishing layer. The through hole is a hole penetrating from the polished surface of the polishing layer to the opposite surface thereof. As a method of providing a through hole in the polishing layer, for example, a through hole is provided by making a hole in the thickness direction of the polishing layer using a die such as a circle, an ellipse, or a polygon (preferably a circular die). Can be done. By using a die, the equivalent circle diameter of the through hole in any polishing layer cross section obtained by cutting the polishing layer of the polishing pad perpendicular to the thickness direction is the diameter of the through hole in any other polishing layer cross section. It can be the same as the diameter equivalent to a circle.

<3. Step of arranging the translucent member so that the translucent member exists in the through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad>
In this step, the translucent member is arranged so that the translucent member exists in the through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. At this time, the translucent member is arranged so that one surface thereof is on the polished surface side.
As a method of arranging the translucent member so that the translucent member exists in the through hole, for example, as shown in (1) FIGS. A method of arranging the translucent member so as to be in contact with (or adhere to) the side surface, or (2) another layer having a through hole having a smaller equivalent circle diameter is provided in the lower layer of the polishing layer as shown in FIG. By arranging the translucent member on the exposed part caused by the difference in size between the through hole of the polishing layer and the through hole of the other layer, the translucent member is arranged so that the translucent member can be seen inside the through hole. (3) A method of sandwiching a translucent member between the polishing layer and another layer as shown in FIG. 5, and a method of exposing a part of the translucent member into the through hole, and (4) Fig. 6 A through hole having the same shape is provided in both the polishing layer and the other layer provided under the polishing layer, and the translucent member is provided in contact with (or adheres to) the side surface of either or both of the through holes. The method of arranging it can be mentioned. Among these, (1), (2) or (4) is preferable, (1) or (2) is more preferable, and (2) is even more preferable.

The manufacturing method of the present invention may include a step of preparing a layer other than the polishing layer, or may include a step of laminating a layer (other layer) other than the polishing layer and the polishing layer. The other layer has the same or different through-holes as the through-holes of the polished layer. The through hole in the other layer may be provided before the other layer is bonded to the polishing layer, or may be provided after the other layer is bonded to the polishing layer. Examples of the other layer and the through hole include the same as described above.
Further, the manufacturing method of the present invention may include a step of providing a second through hole having a diameter equivalent to a circle smaller than the through hole (first through hole) provided in the polishing layer in another layer.

When the polishing pad of the present invention is used, the polishing pad is attached to the polishing surface plate of the polishing machine so that the polishing surface of the polishing layer faces the object to be polished. Then, while supplying the slurry, the polishing surface plate is rotated to polish the processed surface of the object to be polished.
Examples of the object to be polished processed by the polishing pad of the present invention include bare silicon and semiconductor devices. Above all, the polishing pad of the present invention is suitable for polishing semiconductor devices, particularly finish polishing, and is preferable.
As the slurry, any slurry containing water (aqueous slurry) can be used without particular limitation. For example, colloidal silica slurry, cerium oxide slurry and the like can be mentioned.

Using the polishing pad of the present invention, for example, by irradiating a wafer through the polishing pad with a light beam through a translucent member in a through hole during the CMP polishing process and monitoring the interference signal generated by the reflection thereof. While polishing the object to be polished, it is possible to optically detect the surface characteristics of the object to be polished such as a semiconductor wafer and the time when a flat state is reached.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[Example 1]
A 20 cm × 20 cm transparent acrylic resin film (manufactured by Mitsubishi Chemical Corporation, Acryprene HBS006, thickness 150 μm) was prepared, and one surface of the film was hydrophilized by plasma processing. As a result, the translucent member of Example 1 was obtained.

[Example 2]
A 20 cm × 20 cm transparent acrylic resin film (manufactured by Mitsubishi Chemical Corporation, Acryprene HBS006, thickness 150 μm) was prepared, and one surface of the film was hydrophilized by roll blasting. As a result, the translucent member of Example 2 was obtained.

[Comparative Example 1]
A 20 cm × 20 cm transparent acrylic resin film (manufactured by Mitsubishi Chemical Corporation, Acryprene HBS006, thickness 150 μm) was prepared, and this was used as a translucent member of Comparative Example 1.

<Water contact angle measurement>
The water contact angles of the translucent members of Examples 1 and 2 and Comparative Example 1 were measured by the following method using an automatic contact angle meter DropMaster DM500 (manufactured by Kyowa Interface Science Co., Ltd.).
(1) Put distilled water in a syringe, attach a dispenser, and set it in DM500.
(2) Cut the measurement sample into a size of 5 mm x 50 mm and attach it to the stage.
(3) Launch the analysis software, select the contact angle measurement [droplet method], and set each parameter.
Waiting time until measurement: 1000ms
Measurement time interval: 1000ms
Number of continuous measurements: 180 times (4) Set the amount of droplets to be measured and the position of the injection needle on the image monitor, and optimize the focus value of the image monitor.
(5) Droplets are applied to the sample to start the measurement, and the water contact angle 20 seconds after the start of the measurement is read.
The results of the water contact angle measurement test are shown in Table 1.

<Measurement of transmittance>
The visible light transmittances of the translucent members of Examples 1 and 2 and Comparative Example 1 were measured by the following method using an ultraviolet-visible near-infrared spectrophotometer V-770 (manufactured by JASCO Corporation). The visible light transmittance is measured under two conditions, one is when water is attached to the surface of the translucent member (the surface processed for Examples 1 and 2) and the other is when water is not attached. gone.
1. 1. Measurement when water is attached (1) Insert a quartz glass cell and measure the blank.
(2) The translucent members of Examples 1 and 2 and Comparative Example 1 are cut out to a size of 9 mm × 50 mm.
(3) Place the translucent member on the Kimwipe and spray (capacity) on the surface of the translucent member (only the processed surface for Examples 1 and 2 and only one surface for Comparative Example 1) from a position 20 cm away. Spray purified water 3 times with 50 ml (PP bottle) (spray amount per spray: about 0.160 to 0.165 ml, application amount on the surface of translucent member after 3 sprays: about 0.01-0.03 ml). After spraying, the translucent member was placed in a vertical state and allowed to stand for 60 seconds. A translucent member is installed in the quartz glass cell so that the surface not sprayed with water and the inner surface of the quartz glass cell come into contact with each other.
(3) A translucent member is arranged on the inner wall of the quartz glass cell so that the surface treatment surface faces the surface opposite to the light source and the translucent member is in full contact with the light source side of the quartz cell.
(4) Using an ultraviolet-visible near-infrared spectrophotometer V-770 (manufactured by JASCO Corporation), the straight transmittance for light of 250 nm to 1000 nm is measured.
(5) Calculate the visible light transmittance for wavelengths of 380 to 780 nm based on JIS A 5759: 2008.

2. 2. Measurement when water does not adhere (1) Insert a quartz glass cell and measure the blank.
(2) The translucent members of Examples 1 and 2 and Comparative Example 1 are cut out to a size of 9 mm × 50 mm.
(3) A translucent member is arranged on the inner wall of the quartz glass cell so that the surface treatment surface faces the surface opposite to the light source and the translucent member is in full contact with the light source side of the quartz cell.
(4) Using an ultraviolet-visible near-infrared spectrophotometer V-770 (manufactured by JASCO Corporation), the straight transmittance for light of 250 nm to 1000 nm is measured.
(5) Calculate the visible light transmittance for wavelengths of 380 to 780 nm based on JIS A 5759: 2008.

By the above method, the visible light transmittances of the translucent members of Examples 1 and 2 and Comparative Example 1 were determined for each of the cases where water was attached to the surface and the cases where water was not attached. The results are shown in Table 1.

Since the water contact angle of the surface of the translucent member of Comparative Example 1 is more than 80 degrees, there is a large difference in the visible light transmittance between the case where the surface has water and the case where there is no water. On the other hand, since the water contact angle of the surface of the translucent member of Examples 1 and 2 is 80 degrees or less, there is almost a difference in the visible light transmittance between the case where the surface has water and the case where there is no water. It did not occur. Therefore, in the polishing pad including the translucent member of Examples 1 and 2, the visible light transmittance does not vary depending on whether the slurry is present or not on the surface, and the determination of the polishing end point is made more accurately. It can be carried out.

<Manufacturing example 1>
To 100 parts by mass of a solution containing 100% modulus 7.8 MPa polyester polyurethane resin (30 parts by mass) and DMF (70 parts by mass), 60 parts by mass of DMF and 5 parts by mass of water are separately added and mixed to contain the resin. A solution was obtained.
The insoluble component was removed by filtering the obtained resin-containing solution. The solution was cast on a polyester film using a knife coater so that the coating thickness was 0.8 mm. Then, the polyester film cast with the resin-containing solution is immersed in a coagulation bath (the coagulation liquid is water) to coagulate the resin-containing solution, and then the polyester film is peeled off, washed and dried to form a teardrop shape inside. A polyurethane resin film having a plurality of bubbles and having the plurality of bubbles connected to each other and communicated with each other was obtained. The surface of the obtained polyurethane resin film is buffed to a thickness of 0.73 mm, and then a PET resin base material having a thickness of 0.188 μm is bonded to the side opposite to the buffed surface with an adhesive to form a polyurethane resin film. The surface was embossed from the surface side of the above, and grooves having a rectangular cross section with a groove width of 1 mm, a groove spacing of 4 mm, and a groove depth of 0.45 mm were provided on the surface. Make three holes at equal intervals with a circular die with a diameter of 18 mm on a concentric circle at a position that is 1/2 of the radius of the polishing pad from the center position of the polishing pad on the groove processing surface side, and make the first through hole. Provided. Adhere a double-sided tape with a release paper on one side to the side where the polyurethane resin film of the resin base material is not attached, fit a circular die with a diameter of 9 mm into the first through hole with a diameter of 18 mm, and penetrate the double-sided tape and the release paper. A second through hole was opened so as to allow. At this time, drilling was performed so that the center of the first through hole and the center of the second through hole were substantially the same. As a translucent member, prepare an acrylic resin film (manufactured by Mitsubishi Chemical Co., Ltd., acrylicplen HBS006, thickness 150 μm) with one side plasma-treated, cut out three sheets to a diameter of 17 mm, and form a ring in the first through hole. A polishing pad was manufactured by adhering the exposed double-sided tape and the translucent member so that the surface-treated surface side of the translucent member was the polished surface side.

<Manufacturing example 2>
To 100 parts by mass of a solution containing 100% modulus 7.8 MPa polyester polyurethane resin (30 parts by mass) and DMF (70 parts by mass), 60 parts by mass of DMF and 5 parts by mass of water are separately added and mixed to contain the resin. A solution was obtained.
The insoluble component was removed by filtering the obtained resin-containing solution. The solution was cast on a polyester film using a knife coater so that the coating thickness was 0.8 mm. Then, the polyester film cast with the resin-containing solution is immersed in a coagulation bath (the coagulation liquid is water) to coagulate the resin-containing solution, and then the polyester film is peeled off, washed and dried to form a teardrop shape inside. A polyurethane resin film having a plurality of bubbles and having the plurality of bubbles connected to each other and communicated with each other was obtained. The surface of the obtained polyurethane resin film is buffed to a thickness of 0.73 mm, and then a PET resin base material having a thickness of 0.188 μm is bonded to the side opposite to the buffed surface with an adhesive to form a polyurethane resin film. The surface was embossed from the surface side of the above, and grooves having a rectangular cross section with a groove width of 1 mm, a groove spacing of 4 mm, and a groove depth of 0.45 mm were provided on the surface. Double-sided tape with a thickness of about 0.1 mm (PET base material thickness 0.023 mm, adhesiveness on the front and back surfaces of the PET base material) with a release paper on one side on the side where the polyurethane resin film of the resin base material is not attached. The component thickness was 0.04 mm). A circular die with a diameter of 20 mm is used at equal intervals so that the release paper of the double-sided tape can be penetrated on the concentric circles from the center of the polishing pad on the grooved surface side to the position that is 1/2 of the radius of the polishing pad. A hole was made and a first through hole was provided. Peel off the release paper of the double-sided tape, and prepare an acrylic resin film (manufactured by Mitsubishi Chemical Co., Ltd., Acryprene HBS006, thickness 150 μm) having the same diameter as the polishing layer with plasma treatment on one side as a translucent member, and adhere the double-sided tape. The portion and the surface-treated surface side of the translucent member were bonded together. As another layer, prepare a double-sided tape with a thickness of about 0.1 mm (PET substrate thickness 0.023 mm, adhesive component thickness on the front and back surfaces of the PET substrate is 0.04 mm) with a release paper on one side. When viewed in the thickness direction, a second through hole is provided by drilling three holes at positions that overlap with the first through hole, and the translucent member is adhered to the surface side that has not been surface-treated for polishing. Manufactured the pad.

<Manufacturing example 3>
To 100 parts by mass of a solution containing 100% modulus 7.8 MPa polyester polyurethane resin (30 parts by mass) and DMF (70 parts by mass), 60 parts by mass of DMF and 5 parts by mass of water are separately added and mixed to contain the resin. A solution was obtained.
The insoluble component was removed by filtering the obtained resin-containing solution. The solution was cast on a polyester film using a knife coater so that the coating thickness was 0.8 mm. Then, the polyester film cast with the resin-containing solution is immersed in a coagulation bath (the coagulation liquid is water) to coagulate the resin-containing solution, and then the polyester film is peeled off, washed and dried to form a teardrop shape inside. A polyurethane resin film having a plurality of bubbles and having the plurality of bubbles connected to each other and communicated with each other was obtained. The surface of the obtained polyurethane resin film is buffed to a thickness of 0.73 mm, and then a PET resin base material having a thickness of 0.188 μm is bonded to the side opposite to the buffed surface with an adhesive to form a polyurethane resin film. The surface was embossed from the surface side of the above, and grooves having a rectangular cross section with a groove width of 1 mm, a groove spacing of 4 mm, and a groove depth of 0.45 mm were provided on the surface. Another layer was bonded to the surface side where the polyurethane resin film of the resin base material was not bonded via a heat-meltable adhesive. As the other layer, a non-woven fabric produced by a needle punch method from a polyester fiber having a fineness of 2 dtex and a fiber length of 51 mm was used, and the thickness was 0.50 mm and the density was 0.35 g / cm ³ . A double-sided tape having a release paper on one side was adhered to the side on which the non-woven polyurethane resin film was not bonded. A circular die with a diameter of 20 mm is used at equal intervals so that the polishing pad penetrates from the polishing surface to the double-sided tape on a concentric circle at a position that is 1/2 of the radius of the polishing pad from the center position of the polishing pad on the grooved surface side. A hole was made and a first through hole and a second through hole were provided. As a translucent member, three acrylic resin / polycarbonate resin sheets (Technoloy C001, thickness 500 μm, manufactured by Sumitomo Chemical Co., Ltd.) with one side plasma-treated were cut out to a diameter of 20 mm and placed on the side surface of the circular translucent member. A polishing pad was manufactured by applying a hot melt adhesive and adhering the surface-treated surface side of the translucent member to the side surface in the second through hole so that the surface side was the polished surface side.
Since the light transmittance of the polishing pads of Production Examples 1 to 3 does not fluctuate greatly depending on the presence or absence of the aqueous slurry, the polishing end point can be detected with high accuracy.

According to the present invention, it is possible to provide a polishing pad capable of suppressing variations in light transmittance. Therefore, the polishing pad of the present invention is extremely useful in industry.

1 ... Polishing pad 2 ... Polishing layer 3 ... Other layers 4 ... Translucent member 4'... Top 5 of the translucent member ... Through hole (first through hole)
6 ... 2nd through hole 7 ... Exposed part 8 ... Groove 8'... Bottom of groove

Claims (10)

A polishing pad having a translucent member and a polishing layer.
The polishing layer includes a polishing surface for polishing an object to be polished, and the polishing pad has a through hole penetrating from the polishing surface to the opposite surface thereof.
The translucent member is arranged so that the translucent member exists in the through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad, and the translucent member is arranged. The polishing pad having a water contact angle of 80 degrees or less on the surface on the polishing surface side. The polishing pad according to claim 1, wherein the uppermost portion of the translucent member is lower than the polishing surface when the polishing surface is the upper surface and the opposite surface is the lower surface. The polishing pad according to claim 1 or 2, wherein the water contact angle of the surface of the translucent member opposite to the polishing surface side is more than 80 degrees. The polishing pad according to any one of claims 1 to 3, wherein the visible light transmittance when the translucent member is irradiated with light having a wavelength of 380 nm to 780 nm is 60% or more. The polishing pad according to any one of claims 1 to 4, wherein the polishing surface has a groove. The polishing pad according to claim 5, wherein the groove is an embossed groove. The polishing according to claim 5 or 6, wherein the uppermost portion of the translucent member is at the same position as or lower than the lowermost portion of the groove when the polished surface is the upper surface and the opposite surface is the lower surface. pad. The polishing pad according to any one of claims 1 to 7, wherein the shape of the through hole is circular when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. When the through hole of the polishing layer is a first through hole, the polishing pad further includes another layer having a second through hole having a diameter equivalent to a circle smaller than that of the first through hole.
The other layer is located on the side opposite to the polishing surface of the polishing layer.
When the polishing pad is viewed from the polishing surface side in the thickness direction, the first through hole and the second through hole overlap at least partially.
Claims 1 to 1, wherein the translucent member is arranged so that the translucent member exists in the first through hole when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. Item 8. The polishing pad according to any one of 8. A step of preparing a polishing layer and a translucent member having a water contact angle of at least one surface of 80 degrees or less.
The translucent member is arranged so that the translucent member exists in the through hole in the step of providing the through hole in the polishing layer and when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. Step, where the translucent member is arranged such that one surface thereof is on the polished surface side.
The method for manufacturing a polishing pad according to any one of claims 1 to 9, wherein the polishing pad is manufactured.

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