JP2021186951A - Polishing pad and polishing device - Google Patents

Abstract

To provide a polishing pad and a polishing device which enable detection of a temperature during polishing without causing unstable polishing.SOLUTION: A polishing device 10 includes: a chuck table 30 which has a lower surface 32 that is a holding surface for holding a wafer 1 and is rotated around a rotation axis 33 perpendicular to the lower surface 32; a polishing unit 20 which has a polishing pad 12 having a diameter larger than that of the chuck table 30 mounted on an upper surface 24 that is a mounting surface parallel to the lower surface 32 and is rotated around a rotation axis 25 perpendicular to the upper surface 24; and a control unit 100 for detecting a color of the polishing pad 12 during polishing of the wafer 1, and determines a state of the polishing. The polishing pad 12 contains a coating material whose color is reversibly changed according to the temperature. The control unit 100 compares the color of the polishing pad 12 during polishing of the wafer 1 with the color of the polishing pad 12 during previously registered normal polishing, determines whether or not the polishing is normal, and notifies a user of a determination result.SELECTED DRAWING: Figure 2

Description

The present invention relates to a polishing pad and a polishing apparatus for polishing a wafer.

Wafers such as silicon that form semiconductor device chips are polished (for example, Patent Document 1 and Patent Document 1) after the surface opposite to the surface on which the device is formed is ground with a grinding wheel as electronic components become lighter, thinner, shorter, and smaller. (Refer to Document 2), grinding marks are removed, and the chip is generally processed into a thin chip having high bending resistance.

In polishing, various processing methods such as CMP (Chemical Mechanical Polishing) processing using a polishing pad and a slurry solution and polishing using a polishing pad containing abrasive grains and an alkaline or acidic solution are used. In these polishings, it is common that a certain amount of processing heat is generated at the processing point in contact with the polishing pad of the wafer.

Japanese Unexamined Patent Publication No. 2019-102687 Japanese Patent No. 6192778

Therefore, various methods have been devised to monitor the processing status while measuring the temperature of the polishing pad during polishing. For example, a hole is made in a part of the polishing pad and a temperature sensor is placed there to perform polishing. May measure the heat of. However, processing is not performed on the temperature sensor part, which may cause processing instability. Further, since the temperature can be measured only in a certain part of the sensor, there is a problem that the entire area where the polishing pad and the wafer are in contact cannot be inspected.

The present invention has been made in view of such problems, and an object of the present invention is to provide a polishing pad and a polishing apparatus capable of detecting a temperature during polishing without causing instability of polishing. Is.

In order to solve the above-mentioned problems and achieve the object, the polishing pad of the present invention is a polishing pad that is pressed against the surface to be polished of the wafer to polish the wafer, and its color changes reversibly according to the temperature. It is characterized in that the temperature during polishing can be visually recognized by the color of the paint.

The polishing apparatus of the present invention is a polishing apparatus that polishes a wafer using the polishing pad, and has a holding surface for holding the wafer, and a chuck table that rotates on a rotation axis orthogonal to the holding surface, and the holding. A polishing pad having a diameter larger than that of the chuck table is mounted on a mounting surface parallel to the surface, and a polishing unit that rotates on a rotation axis orthogonal to the mounting surface and the color of the polishing pad that is polishing the wafer are detected. A determination unit for determining the polishing state is provided, and the determination unit includes a color of the polishing pad detected during polishing of the wafer and a color of the polishing pad at the time of normal or abnormal polishing registered in advance. It is characterized in that it is determined whether or not the polishing is normal by comparing with and, and the determination result is notified.

In the polishing apparatus, the determination unit may determine whether or not the region where the color of the polishing pad has changed is smaller than the preset region, and may notify the determination result.

The present invention has the effect of making it possible to detect the temperature during polishing without causing instability in polishing.

FIG. 1 is a perspective view showing an example of a wafer to be polished by the polishing apparatus according to the first embodiment. FIG. 2 is a side view showing a schematic configuration of the polishing apparatus according to the first embodiment. FIG. 3 is a plan view of the polishing apparatus shown in FIG. FIG. 4 is a plan view showing a polishing pad and the like immediately after the start of polishing of the polishing apparatus shown in FIG. FIG. 5 is a plan view showing an example of a polishing pad and the like during polishing of the polishing apparatus shown in FIG. FIG. 6 is a plan view showing another example such as a polishing pad during polishing of the polishing apparatus shown in FIG. FIG. 7 is a side view showing a schematic configuration of the polishing apparatus according to the second embodiment. FIG. 8 is a side view showing a schematic configuration of a polishing apparatus according to a modification of the first embodiment and the second embodiment.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

[Embodiment 1]
The polishing pad and the polishing apparatus according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a wafer to be polished by the polishing apparatus according to the first embodiment. FIG. 2 is a side view showing a schematic configuration of the polishing apparatus according to the first embodiment. FIG. 3 is a plan view of the polishing apparatus shown in FIG. FIG. 4 is a plan view showing a polishing pad and the like immediately after the start of polishing of the polishing apparatus shown in FIG. FIG. 5 is a plan view showing an example of a polishing pad and the like during polishing of the polishing apparatus shown in FIG. FIG. 6 is a plan view showing another example such as a polishing pad during polishing of the polishing apparatus shown in FIG.

The polishing apparatus 10 shown in FIG. 2 according to the first embodiment is a processing apparatus for polishing the wafer 1 shown in FIG. The wafer 1 to be polished by the polishing device 10 is a disk-shaped semiconductor wafer or an optical device wafer having silicon, sapphire, gallium arsenide, or the like as the substrate 2. In the first embodiment, the substrate 2 of the wafer 1 is made of single crystal silicon, and the wafer 1 is a single crystal silicon wafer.

As shown in FIG. 1, in the wafer 1, a grid-like division schedule line 4 is formed on the surface 3 of the substrate 2, and a device 5 is formed in each region partitioned by the division schedule line 4. The device 5 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).

The polishing apparatus 10 shown in FIG. 2 is a processing apparatus for polishing the back surface 6 (the surface on the back surface of the surface 3), which is the surface to be polished of the wafer 1. The polishing apparatus 10 shown in FIG. 2 is a processing apparatus for polishing the back surface 6 by bringing the polishing pad 12 into contact with the back surface 6 of the wafer 1 while supplying the polishing liquid 11 to the back surface 6 of the wafer 1, that is, polishing. This is a polishing device that polishes the wafer 1 using the pad 12.

As shown in FIG. 2, the polishing apparatus 10 includes a polishing unit 20, a chuck table 30, a polishing liquid supply nozzle 40, an image pickup unit 50, and a control unit 100 as a determination unit.

The polishing unit 20 includes a disk-shaped polishing wheel 21 having a diameter larger than the diameter of the wafer 1 and a spindle 22 having the polishing wheel 21 attached to the upper end. The polishing wheel 21 includes a wheel base 23 made of a metal such as stainless steel, and a polishing pad 12.

The wheel base 23 is formed in a disk shape having a diameter larger than the diameter of the wafer 1, and the upper surface 24, which is a mounting surface, is flat along the horizontal direction. The polishing pad 12 is pressed against the back surface 6 of the wafer 1 to polish the wafer 1. The polishing pad 12 is formed in a disk shape having a diameter larger than the diameter of the wafer 1 and smaller than the diameter of the wheel base 23, and is mounted on the upper surface 24 of the wheel base 23. The polishing pad 12 is formed in a disk shape having a constant thickness, and is arranged at a position coaxial with the wheel base 23.

The polishing wheel 21 has a wheel base 23 attached to the upper end of the spindle 22, and is rotatably provided around a rotation axis 25 parallel to the vertical direction orthogonal to the upper surface 24 by the spindle 22. In this way, the polishing unit 20 has the polishing pad 12 mounted on the upper surface 24 of the wheel base 23, and is rotated by the spindle 27 on the rotating shaft 25.

In the first embodiment, the polishing pad 12 is, for example, a fixed abrasive grain polishing pad shown in WO2003 / 101668, for example, the abrasive grains are dispersed and fixed in a resin material such as urethane foam. be. In the first embodiment, the abrasive grains of the polishing pad 12 are composed of, for example, a GC (Green Carbide) having a particle size of 0.2 μm or more and 1.5 μm or less. Further, the polishing pad 12 may contain GC abrasive grains in the non-woven fabric instead of urethane foam.

The abrasive grains may be any as long as they have a hardness higher than that of the wafer 1 and can damage the wafer 1. In the first embodiment, since the wafer 1 is a single crystal silicon wafer, a substance having a Mohs hardness of 5 or more is mainly used. The abrasive material used as the material is preferable, and for example, the abrasive grains such as diamond, alumina, ceria, and CBN may be used instead of the GC abrasive grains. In the polishing unit 20, the back surface 6 of the wafer 1 is placed on the polishing pad 12.

Further, the polishing pad 12 contains a paint whose color reversibly changes depending on the temperature in the resin material described above. The paint is a reversible paint that emits a predetermined color 124 at room temperature, decolorizes at a predetermined temperature when the temperature rises, and develops a predetermined color 124 when the temperature drops below the predetermined temperature. Since the polishing pad 12 contains the above-mentioned paint, the entire polishing pad 12 emits a predetermined color 124 at room temperature, the entire polishing pad 12 is decolorized at a predetermined temperature when the temperature rises, and the entire polishing pad 12 emits a predetermined color when the temperature drops below the predetermined temperature. Will develop a predetermined color 124. Therefore, the color of the polishing pad 12 changes when the wafer 1 is normally polished from the start of polishing.

As the paint, Metamocolor (registered trademark) manufactured by Pilot Ink Co., Ltd., Thermal Color (registered trademark) OR manufactured by Recording Material Research Institute Co., Ltd., or Thermal Color (registered trademark) ER can be used. In the first embodiment, the polishing pad 12 contains, for example, a paint having a predetermined temperature of 60 ° C., emits a predetermined color 124 at a predetermined temperature, decolorizes at 60 ° C. when the temperature rises, and has a temperature lower than 60 ° C. And the predetermined color 124 will be developed. The polishing pad 12 is obtained by mixing abrasive grains, a capsule slurry containing paint (a capsule containing a slurry containing paint), powder, or pellets, and molding the polishing pad 12 into a predetermined shape. The polishing pad 12 according to the first embodiment can visually recognize the temperature during polishing by changing the color of the paint contained in the resin material being polished.

The chuck table 30 has a disk shape, and as shown in FIG. 2, it is mounted on the lower end of the spindle 31 and the lower surface 32 faces the polishing pad 12. The diameter of the chuck table 30 is larger than the diameter of the wafer 1 and smaller than the diameter of the wheel base 23 of the polishing wheel 21 and the polishing pad 12. The chuck table 30 has a lower surface 32 that is flat along the horizontal direction and is a holding surface formed of porous ceramic or the like, and holds the wafer 1 on the lower surface 32. That is, the chuck table 30 has a holding surface parallel to the upper surface 24 which is a mounting surface. The chuck table 30 is connected to a vacuum suction source (not shown) and is sucked by the vacuum suction source to suck and hold the wafer 1 on the lower surface 32. In the first embodiment, the chuck table 30 sucks and holds the surface 3 side of the wafer 1.

The chuck table 30 is rotated by the spindle 31 around a rotation axis 33 parallel to the vertical direction and orthogonal to the lower surface 32 which is a holding surface. The chuck table 30 presses the wafer 1 sucked and held on the lower surface 32 against the polishing pad 12 along the vertical direction while rotating around the rotation shaft 33 by the spindle 31. The chuck table 30 causes the polishing pad 12 to polish the back surface 7 of the wafer 1 by pressing the wafer 1 sucked and held on the lower surface 32 along the vertical direction.

Further, in the first embodiment, the lower surface 32, which is the holding surface of the chuck table 30, faces the polishing pad 12 over the center of the polishing pad 12 and one end in the horizontal direction shown on the left side in FIG. Further, since the diameter of the chuck table 30 is smaller than the diameters of the wheel base 23 of the polishing wheel 21 and the polishing pad 12, the other end of the upper surface 121 of the polishing pad 12 in the horizontal direction is exposed during polishing. Will be. In this way, in the polishing apparatus 10 according to the first embodiment, the chuck table 30 that sucks and holds the wafer 1 is arranged above the polishing unit 20 so as to face the polishing pad 12 of the polishing unit 20 that polishes the back surface 6 of the wafer 1. ing.

The polishing liquid supply nozzle 40 supplies the polishing liquid 11 supplied from a polishing liquid supply source (not shown) onto the polishing pad 12 of the polishing unit 20. In the first embodiment, the polishing liquid supply nozzle 40 vertically faces the upper surface 121 of the polishing pad 12 of the polishing unit 20 and supplies the polishing liquid 11 to the upper surface 121 of the polishing pad 12.

In the first embodiment, the polishing liquid 11 is composed only of an alkaline polishing liquid (also referred to as a chemical liquid), that is, does not contain abrasive grains. The polishing liquid 11 is an alkaline aqueous solution having a pH (potential of Hydrogen) of 9 or more and 13 or less, and in the first embodiment, it is an alkaline aqueous solution having a pH of 10.0 or more and 11.4 or less.

The image pickup unit 50 faces the other end in the horizontal direction shown on the right side in FIGS. 2 and 3 of the polishing pad 12 of the polishing unit 20 in the vertical direction. The image pickup unit 50 includes an image pickup element that images the upper surface 121 of the polishing pad 12, except for the portion where the back surface 6 of the wafer 1 of the polishing pad 12 is polished. The image sensor is, for example, a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary MOS) image sensor. The image pickup unit 50 takes an image of the upper surface of the polishing pad 12 which is not in contact with the back surface 6 of the wafer 1 during polishing, and outputs the image obtained by taking the image to the control unit 100. The image acquired by the image pickup unit 50 is a so-called color image including the intensity of R (red) light, the intensity of G (green) light, and the intensity of B (blue) light.

The control unit 100 controls each of the above-mentioned components constituting the polishing apparatus 10. That is, the control unit 100 causes the polishing device 10 to perform a polishing operation on the wafer 1. The control unit 100 is a computer capable of executing a computer program. The control unit 100 includes an arithmetic processing unit having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input / output interface device. And have. The arithmetic processing unit of the control unit 100 executes a computer program stored in the storage device to generate a control signal for controlling the polishing device 10. The arithmetic processing unit of the control unit outputs the generated control signal to each component of the polishing device 10 via the input / output interface device.

Further, the control unit 100 includes a display unit 110 composed of a liquid crystal display device for displaying a processing operation state, an image, and the like, an input unit 120 used by an operator to register processing content information, and a notification unit 130. Is connected to. The input unit 120 is composed of at least one of a touch panel provided on the display unit 110 and an external input device such as a keyboard. The notification unit 130 emits at least one of sound and light to notify the operator.

Further, the control unit 100 includes a normal data storage unit 101 and a determination unit 102. The normal data storage unit 101 stores normal color data 103 indicating the color of the upper surface 121 of the polishing pad 12 which is normally maintained during polishing after a predetermined time has elapsed from the start of polishing the wafer 1. The normal color data 103 includes normal intensity, which is the intensity of R (red) light of an image obtained by imaging the upper surface 121 of the polishing pad 12 during normal polishing of wafer 1 by the image pickup unit 50, and G (green). ) Is the normal intensity of light, and B (blue) is the intensity of normal light.

The determination unit 102 determines the intensity of R (red) light, which is the color information of the polishing pad 12, and G from the image obtained by imaging the upper surface 121 of the polishing pad 12 while the wafer 1 is being polished by the image pickup unit 50. (Green) light intensity and B (blue) light intensity are detected. The determination unit 102 has R (red) light intensity, G, which is color information of the polishing pad 12 detected from an image obtained by imaging the upper surface 121 of the polishing pad 12 while the wafer 1 is being polished by the image pickup unit 50. The polishing state of the wafer 1 by the polishing pad 12 is determined by comparing the light intensity of (green) and the light intensity of B (blue) with the normal color data 103 stored in the normal data storage unit 101. do. In this way, the determination unit 102, that is, the control unit 100 detects the color of the polishing pad 12 while the wafer 1 is being polished, and determines the polishing state of the wafer 1 by the polishing pad 12.

At the time of determination, the determination unit 102 determines the intensity of the R (red) light and the intensity of the G (green) light detected from the image obtained by imaging the upper surface 121 of the polishing pad 12 while the wafer 1 is being polished by the image pickup unit 50. The intensity, the intensity of the B (blue) light, the normal intensity of the R (red) light of the normal color data 103 stored in the normal data storage unit 101, the normal intensity of the G (green) light, and the normal intensity of the G (green) light. Compare with the normal intensity of B (blue) light. Specifically, the determination unit 102 determines the difference between the intensity of the R (red) light detected from the image captured by the image pickup unit 50 and the normal intensity of the R (red) light of the normal color data 103. Is lower than the predetermined value stored in advance, and the intensity of the G (green) light detected from the image obtained by the image pickup unit 50 and the normal intensity of the G (green) light of the normal color data 103 The difference is lower than the predetermined value stored in advance, and the intensity of the B (blue) light detected from the image obtained by the image pickup unit 50 and the normal intensity of the B (blue) light of the normal color data 103. The area of the portion 123 (the portion shown by a white background in the polishing region 122 described later on the upper surface 121 of the polishing pad 12 in FIGS. 5 and 6) in which the difference between the two is lower than the predetermined value stored in advance is calculated. In the first embodiment, the portion 123 is not only the decolorized portion of the polishing pad 12 but also the region where the color of the polishing pad 12 has changed from the start of polishing after a lapse of a predetermined time from the start of polishing.

The determination unit 102 determines whether or not the calculated area of the portion 123 is smaller than the area (area) stored (set) in the storage device in advance. When the determination unit 102 determines that the calculated area of the portion 123 is not smaller than the area (area) stored (set) in the storage device in advance (that is, is equal to or larger than the area (area)), the wafer by the polishing pad 12 is used. It is determined that the polishing of 1 is normal, the determination result is displayed on the display unit 110, and the determination result is notified to the operator. Further, when the determination unit 102 determines that the calculated area of the portion 123 is smaller than the area (area) stored (set) in the storage device in advance, the determination unit 102 determines that the polishing of the wafer 1 by the polishing pad 12 is abnormal. The determination result is displayed on the display unit 110, and one of sound and light is emitted from the notification unit 130 to notify the operator of the determination result.

Thus, in the first embodiment, the determination unit 102, that is, the control unit 100 is maintained at the time of normal polishing after a predetermined time has elapsed from the color of the polishing pad 12 detected while polishing the wafer 1 and the start of polishing registered in advance. By comparing with the color of the polishing pad 12, it is determined whether or not the polishing is normal, and the determination result is notified. Further, in the first embodiment, the polishing pad 12 develops a predetermined color 124 at room temperature at the start of polishing, and the entire wafer 1 is decolorized after a predetermined time has elapsed from the start of polishing in a state where the wafer 1 is normally polished. In the determination unit 102, that is, the control unit 100, the portion 123 that has been decolorized after a predetermined time has elapsed from the start of polishing, which is the region where the color of the polishing pad 12 has changed, is smaller than the preset region. It is determined whether or not the polishing is normal, and the determination result is notified.

The function of the normal data storage unit 101 is realized by the above-mentioned storage device. The function of the determination unit 102 is realized by the above-mentioned arithmetic processing unit executing a computer program stored in the storage device.

In the polishing apparatus 10 according to the first embodiment, the wafer 1 is placed on the polishing pad 12, the lower surface 32 of the chuck table 30 is brought into contact with the surface 3 side of the wafer 1 on the polishing pad 12, and the operator provides processing content information. When the control unit 100 registers with the control unit 100 and the control unit 100 receives an instruction to start the machining operation from the operator, the polishing operation is started. In the polishing operation, in the polishing device 10, the control unit 100 controls the vacuum suction source to suck and hold the surface 3 side of the wafer 1 on the lower surface 32 of the chuck table 30.

In the polishing operation, in the polishing device 10, the control unit 100 rotates the polishing wheel 21 of the polishing unit 20 around the rotation axis 25 while supplying the polishing liquid 11 from the polishing liquid supply nozzle 40 to the upper surface 121 of the polishing pad 12, and chucks the polishing device 10. The table 30 is rotated around the rotation axis 33. Therefore, in the polishing operation, the polishing apparatus 10 makes the back surface 6 of the wafer 1 come into contact with the inside of the broken line shown in FIG. 3 on the outer peripheral side of the outer edge of the polishing pad 12 to polish. The area inside the broken line shown in FIG. 3 of the polishing pad 12 is hereinafter referred to as the polishing area 122 of the polishing pad 12.

In the polishing operation, the polishing apparatus 10 brings the wafer 1 close to the polishing unit 20 at a predetermined feed rate on the chuck table 30 while rotating the polishing wheel 21 and the chuck table 30 around the rotation shafts 25 and 33, whereby the polishing pad is used. The back surface 7 of the wafer 1 is polished with 12. The polishing liquid 11 supplied onto the polishing pad 12 moves on the polishing pad 12 in the outer peripheral direction of the polishing unit 20 due to the centrifugal force accompanying the rotation around the axis of the polishing unit 20, and the back surface 6 of the wafer 1 and the polishing pad. Infiltrate between 12 and 12.

Further, since the polishing pad 12 is at room temperature at the start of polishing, the polishing apparatus 10 emits a predetermined color 124 shaded in FIG. 4 as a whole including the polishing region 122. When the polishing device 10 polishes the wafer 1, the temperature of the polishing pad 12 rises and approaches a predetermined temperature, and when the temperature reaches a certain temperature lower than the predetermined temperature, the polishing pad 12 starts to be decolorized, and the polishing pad 12 starts to be decolorized. When the temperature reaches a predetermined temperature, the polishing pad 12 erases the predetermined color 124. In the first embodiment, the constant temperature is 5 ° C., which is lower than the predetermined temperature, but is not limited to 5 ° C. in the present invention.

In the first embodiment, in the polishing apparatus 10, when the polishing pad 12 normally polishes the wafer 1, after a predetermined time elapses from the start of polishing the wafer 1, the entire polishing pad 12 reaches a predetermined temperature, and FIG. As shown in the above, the entire inside of the polishing area 122 of the polishing pad 12 disappears and the predetermined color 124 disappears. Further, in the first embodiment, the polishing apparatus 10 keeps the entire polishing pad 12 at a predetermined temperature after a predetermined time has elapsed from the start of polishing the wafer 1, and the entire polishing pad 12 in the polishing region 122. Maintains the decolorized state.

Further, during polishing, when a predetermined time elapses from the start of polishing of the wafer 1, the control unit 100 controls the image pickup unit 50 to cause the image pickup unit 50 to take an image of the polishing pad 12. In the polishing device 10, the determination unit 102 of the control unit 100 captures the image obtained by the image pickup unit 50, and the intensity of the R (red) light, which is the color information of the polishing pad 12, and the light of G (green). And the intensity of B (blue) light are detected. In the polishing device 10, the determination unit 102 of the control unit 100 has R (red) light intensity, which is color information of the polishing pad 12 detected from the image obtained by the image pickup unit 50, and G (green). Light intensity, B (blue) light intensity, R (red) light intensity of normal color data 103 stored in the normal data storage unit 101, and G (green) light intensity. The normal intensity and the normal intensity of B (blue) light are compared, and the area of the portion 123 whose above-mentioned difference in intensity is lower than the predetermined value stored in advance is calculated.

The polishing device 10 determines whether or not the calculated area of the portion 123 is smaller than a predetermined area (area) stored (set) in the storage device in advance by the determination unit 102 of the control unit 100, and the polishing pad 12 determines. It is determined whether or not the polishing of the wafer 1 is normal. For example, in the polishing device 10, when the image obtained by the image pickup unit 50 is completely decolorized in the polishing area 122 of the polishing pad 12 as shown in FIG. 5, the calculated area of the portion 123 is predetermined. It is determined that the area is equal to or larger than the area (area), it is determined that the polishing of the wafer 1 by the polishing pad 12 is normal, the determination result is displayed on the display unit 110, and the determination result is notified to the operator.

Further, in the polishing apparatus 10, if there is a portion where the image obtained by the image pickup unit 50 emits a predetermined color 124 of the polishing pad 12 as shown in FIG. 6, the area of the calculated portion 123 is a predetermined region. It is determined that it is smaller than (area), it is determined that the polishing of the wafer 1 by the polishing pad 12 is abnormal, the determination result is displayed on the display unit 110, and one of sound and light is emitted from the notification unit 130. , Notify the operator of the determination result. The polishing apparatus 10 ends the polishing operation when the predetermined polishing of the back surface 6 of the wafer 1 is completed.

The polishing pad 12 according to the first embodiment described above contains a paint whose color changes reversibly according to the temperature in the resin material, so that the color changes according to the temperature during polishing. Therefore, the polishing pad 12 can recognize the temperature of the polishing pad 12 by visually recognizing the color of the polishing pad 12 during polishing. As a result, the polishing pad 12 can detect the temperature without making a hole in a part and arranging a temperature sensor there, and can detect the temperature during polishing without causing instability of polishing. It can be possible.

Further, since the polishing device 10 includes the polishing pad 12 described above, it is possible to detect the temperature during polishing without causing instability of polishing. Further, since the color of the polishing pad 12 and the polishing device 10 changes depending on the temperature during polishing, whether or not an appropriate type of polishing liquid 11 is used in polishing, that is, the polishing processing conditions are appropriate. It is possible to confirm whether or not the polishing liquid 11 has been changed to an appropriate one, and whether or not the polishing liquid 11 has been changed to an appropriate processing condition.

For example, as shown in Patent Document 2, the polishing pad 12 and the polishing device 10 generate different processing heat even if the polishing liquid is changed from an alkaline aqueous solution to pure water during polishing, so that the color of the polishing pad 12 is different. By the change, it can be confirmed whether or not the polishing liquid 11 is appropriately changed.

Further, the polishing apparatus 10 compares the color of the polishing pad 12 detected while polishing the wafer 1 with the color of the polishing pad 12 at the time of normal polishing registered in advance, and determines whether or not the polishing is normal. A determination unit 102, that is, a control unit 100, for determining and notifying the determination result is provided. As a result, the polishing apparatus 10 can recognize whether or not the polishing is normal during the polishing of the wafer 1.

Further, the polishing device 10 determines whether or not the determination unit 102, that is, the control unit 100, has a portion 123 that has been decolorized after a lapse of a predetermined time from the start of polishing, which is a region where the color of the polishing pad 12 has changed, smaller than a preset region. Since the determination is made to determine whether the polishing is normal and the determination result is notified, by recognizing the color of the polishing pad 12, whether the polishing pad 12 is properly in contact with the entire back surface 6 of the wafer 1 or not is polished. It can also be recognized whether the pads 12 are in contact with each other with a uniform pressure.

[Embodiment 2]
The polishing apparatus according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a side view showing a schematic configuration of the polishing apparatus according to the second embodiment. In FIG. 7, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the polishing apparatus 10 according to the second embodiment, as shown in FIG. 7, the control unit 100 includes an abnormal data storage unit 104 instead of the normal data storage unit 101, and the determination content of the determination unit 102 is different. Same as 1. The abnormality data storage unit 104 stores the abnormality color data 105 indicating the color of the upper surface 121 of the polishing pad 12 during polishing of the wafer 1 in an abnormal state. The abnormal color data 105 includes an abnormal intensity which is the intensity of R (red) light of an image obtained by imaging the upper surface 121 of the polishing pad 12 in which the wafer 1 is being polished in an abnormal state by the imaging unit 50, and G. It includes an abnormal intensity which is the intensity of (green) light and an abnormal intensity which is the intensity of B (blue) light.

Similar to the first embodiment, the determination unit 102 has R (red) light intensity and G (green) from the image obtained by the image pickup unit 50 taking an image of the upper surface 121 of the polishing pad 12 while the wafer 1 is being polished. ) And the light intensity of B (blue) are detected. The determination unit 102 determines the intensity of R (red) light, which is color information of the polishing pad 12 detected from the image obtained by imaging the upper surface 121 of the polishing pad 12 while the wafer 1 is being polished by the image pickup unit 50. The state of polishing of the wafer 1 by the polishing pad 12 by comparing the light intensity of G (green), the light intensity of B (blue), and the abnormal color data 105 stored in the abnormal data storage unit 104. Is determined.

At the time of determination, the determination unit 102 determines the intensity of the R (red) light and the intensity of the G (green) light detected from the image obtained by imaging the upper surface 121 of the polishing pad 12 while the wafer 1 is being polished by the image pickup unit 50. Intensity, B (blue) light intensity, R (red) light abnormal intensity of abnormal color data 105 stored in the abnormal data storage unit 104, G (green) light abnormal intensity, and Compare with the abnormal intensity of B (blue) light. Specifically, the determination unit 102 has a difference between the intensity of the R (red) light detected from the image captured by the imaging unit 50 and the abnormal intensity of the R (red) light of the abnormal color data 105. The difference between the intensity of G (green) light detected from the image obtained by the image pickup unit 50 and the intensity of G (green) light of the abnormal color data 105 at the time of abnormality is equal to or higher than a predetermined value stored in advance. The difference between the intensity of the B (blue) light detected from the image obtained by the image pickup unit 50 and the abnormal intensity of the B (blue) light of the abnormal color data 105 is equal to or higher than the predetermined value stored in advance. The area of the portion 123 (the portion shown by the white background in the polishing region 122 of the upper surface 121 of the polishing pad 12 in FIGS. 5 and 6) which is equal to or larger than the predetermined value stored in advance is calculated. In the first embodiment, the portion 123 is also a decolorized portion of the polishing pad 12 after a predetermined time has elapsed from the start of polishing.

The determination unit 102 determines whether or not the calculated area of the portion 123 is smaller than the area (area) stored (set) in the storage device in advance. When the determination unit 102 determines that the calculated area of the portion 123 is not smaller than the area (area) stored (set) in the storage device in advance (that is, is equal to or larger than the area (area)), the wafer by the polishing pad 12 is used. It is determined that the polishing of 1 is normal, the determination result is displayed on the display unit 110, and the determination result is notified to the operator. Further, when the determination unit 102 determines that the calculated area of the portion 123 is smaller than the area (area) stored (set) in the storage device in advance, the determination unit 102 determines that the polishing of the wafer 1 by the polishing pad 12 is abnormal. The determination result is displayed on the display unit 110, and one of sound and light is emitted from the notification unit 130 to notify the operator of the determination result.

Thus, in the first embodiment, the determination unit 102, that is, the control unit 100, compares the color of the polishing pad 12 detected while polishing the wafer 1 with the color of the polishing pad 12 at the time of abnormal polishing registered in advance. Then, it is determined whether or not the polishing is normal, and the determination result is notified. Further, in the first embodiment, the polishing pad 12 develops a predetermined color 124 at room temperature at the start of polishing, and the entire surface is decolorized when a predetermined time elapses from the start of polishing in a state where the wafer 1 is normally polished. The determination unit 102, that is, the control unit 100 determines whether or not the portion 123 that has been decolorized after a predetermined time has elapsed from the start of polishing, which is the region where the color of the polishing pad 12 has changed, is smaller than the preset region. Judgment is made, it is judged whether or not polishing is normal, and the judgment result is notified.

As in the first embodiment, the polishing pad 12 according to the second embodiment contains a paint whose color changes reversibly according to the temperature in the resin material, so that the color changes according to the temperature during polishing. In addition, it is possible to detect the temperature without making a hole in a part and placing a temperature sensor there, and it is possible to detect the temperature during polishing without causing instability of polishing. ..

Further, since the polishing device 10 is provided with the polishing pad 12 described above, it is possible to detect the temperature during polishing without causing instability of polishing, as in the first embodiment.

[Modification example]
The polishing apparatus according to the first and second embodiments of the present invention will be described with reference to the drawings. FIG. 8 is a side view showing a schematic configuration of a polishing apparatus according to a modification of the first embodiment and the second embodiment. In FIG. 8, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the polishing apparatus 10-1 according to the modified example, as shown in FIG. 8, the chuck table 30 that sucks and holds the wafer 1 is opposed to the polishing pad 12 of the polishing unit 20 that polishes the back surface 6 of the wafer 1, and is a polishing unit. It is placed below 20.

In the polishing unit 20 of the polishing apparatus 10-1 according to the modified example, the polishing wheel 21 is attached to the lower end of the spindle 27, the polishing pad 12 is attached to the lower surface 26 which is the mounting surface of the wheel base 23, and the polishing pad 12 is chucked. It is pressed along the vertical direction toward the wafer 1 attracted and held by the table 30.

The chuck table 30 of the polishing apparatus 10-1 according to the modified example is a holding surface in which the upper surface 34 faces the polishing pad 12 and sucks and holds the surface 3 of the wafer 1. The chuck table 30 of the polishing apparatus 10-1 according to the modified example is attached to the upper end of the spindle 31.

Further, the polishing apparatus 10-1 according to the modified example is provided at the center of the spindle 27 and the polishing wheel 21, and supplies the polishing liquid 11 through the polishing liquid supply passage 41 opened in the lower surface 125 of the polishing pad 12, and also deforms. The image pickup unit 50 of the polishing apparatus 10-1 according to the example is arranged below the lower surface 125 of the polishing pad 12, and images the lower surface 125 of the polishing pad 12.

Similar to the first and second embodiments, the polishing pad 12 and the polishing apparatus 10 according to the modified example include a paint whose color changes reversibly depending on the temperature in the resin material, so that the temperature during polishing can be adjusted. Since the color changes accordingly, it is possible to detect the temperature without making a hole in a part and placing a temperature sensor there, and to detect the temperature during polishing without causing instability of polishing. Can be made possible.

The present invention is not limited to the above embodiment. That is, it can be variously modified and carried out within a range that does not deviate from the gist of the present invention. For example, in the present invention, the polishing pad 12 may contain a plurality of paints having different temperatures at which the resin materials are decolorized from each other. In this case, in addition to the paint that the polishing pad 12 develops a predetermined color 124 at room temperature at the start of polishing and the entire surface is decolorized after a predetermined time has passed from the start of polishing in a state where the wafer 1 is normally polished, a predetermined color is specified at room temperature. It may contain a second paint that develops a second predetermined color different from the color 124 and erases the color at a second predetermined temperature higher than the predetermined temperature. In this case, when the polishing pad 12 maintains a predetermined temperature, the paint is decolorized and a second predetermined color of the second paint is developed. Therefore, the polishing is normal by detecting the color of the polishing pad 12. It is possible to determine whether or not the color is present, and the second paint is also decolorized when the temperature reaches a second predetermined temperature higher than the predetermined temperature. Therefore, by detecting the color of the polishing pad 12, the polishing pad 12 being polished It is also possible to detect abnormalities in polishing in which the temperature becomes higher than a predetermined temperature. Further, in the present invention, the polishing pad 12 may include a paint that does not develop a color at room temperature (before the start of polishing) but develops a predetermined color at a predetermined temperature in the resin material. That is, in the present invention, the polishing pad 12 may not develop color at room temperature (before the start of polishing).

In addition, the abnormality of polishing that the polishing pad 12 becomes higher than a predetermined temperature during polishing is that the polishing liquid 11 is insufficient, the temperature of the polishing liquid 11 is too high, or the pressing force of the wafer 1 of the polishing pad 12 is high. It is thought that it is caused by passing. Further, the reason why the polishing pad 12 during polishing becomes lower than a predetermined temperature is that the polishing liquid 11 is excessive, the temperature of the polishing liquid 11 is too low, or the pressing force of the wafer 1 of the polishing pad 12 is too low. Is thought to be the cause.

1 Wafer 6 Back side (polished surface)
10 Polishing device 11 Polishing liquid 12 Polishing pad 20 Polishing unit 24 Top surface (mounting surface)
25 Rotating shaft 26 Bottom surface (mounting surface)
30 Chuck table 32 Bottom surface (holding surface)
33 Rotating shaft 34 Top surface (holding surface)
100 Control unit (judgment unit)
123 parts (area where the color of the polishing pad changed)

Claims (3)

A polishing pad that is pressed against the surface to be polished of the wafer to polish the wafer.
A polishing pad that contains a paint whose color changes reversibly according to the temperature, and the temperature during polishing can be visually recognized by the color of the paint. A polishing apparatus for polishing a wafer using the polishing pad according to claim 1.
A chuck table having a holding surface for holding a wafer and rotating on a rotation axis orthogonal to the holding surface,
A polishing unit having a diameter larger than that of the chuck table mounted on a mounting surface parallel to the holding surface and rotating on a rotation axis orthogonal to the mounting surface, and a polishing unit.
A determination unit that detects the color of the polishing pad during polishing of the wafer and determines the polishing state is provided.
The determination unit compares the color of the polishing pad detected while polishing the wafer with the color of the polishing pad at the time of normal or abnormal polishing registered in advance, and determines whether or not the polishing is normal. A polishing device that notifies the judgment result. The polishing device according to claim 2, wherein the determination unit determines whether or not the region where the color of the polishing pad has changed is smaller than a preset region, and notifies the determination result.

Images