CMP grinding equipment

Abstract

To provide a CMP polishing device, which can remove machining chips adhering to a holding surface without grinding the holding surface, so as to keep in-plane thicknesses of a machined wafer uniform.SOLUTION: A CMP polishing device 1, which is provided with a chuck table 10, a polishing pad 35 that polishes an upper surface of a wafer 100 by rotating and a slurry supply part 50 that supplies slurry to an upper surface of the wafer 100 from a center O2 of the polishing pad 35, is further provided with an irrotational cylindrical tube 60 arranged to surround the polishing pad 35 and a plurality of air jet ports 641 and 651, arranged on an inner peripheral surface of the cylindrical tube 60, which jets air in a direction from a lower surface of an outer periphery of the polishing pad 35 toward a center, where the inner peripheral surface of the cylindrical tube 60 receives slurry spattered from an outer periphery of the polishing pad 35 to outside in a radial direction by centrifugal force of the polishing pad 35 which is rotating, so that the slurry is caused to adhere to the polishing pad 35, by air jetted from the air jet ports 641 and 651 opening to the inner peripheral surface.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a CMP polishing apparatus for polishing a wafer while supplying a slurry.

Background Art

[0002] When grinding the back surface of a wafer by pressing it while rotating a grinding wheel, grinding marks remain on the back surface of the wafer, and these grinding marks cause a decrease in the flexural strength of the wafer.

[0003] Therefore, it is performed to remove the grinding marks by polishing the back surface of the wafer with a polishing apparatus. The polishing of the wafer by this polishing apparatus is performed, for example, by a method called CMP (Chemical Mechanical Polishing). Specifically, while supplying a slurry (polishing liquid) containing free abrasive grains to the polishing surface of a polishing pad, the back surface of the wafer is polished by pressing the rotating polishing pad against the back surface of the wafer.

[0004] In the polishing of a wafer by a CMP polishing apparatus as described above, it is necessary to continuously supply a slurry between the wafer and the polishing pad. However, if a new slurry is always supplied, there arises a problem that the processing cost increases.

[0005] Therefore, for example, in Patent Documents 1 and 2, there have been proposed polishing apparatuses in which the slurry used for polishing is stored in a container, and the stored slurry is sprayed onto the polishing pad by air and reattached to the polishing pad, thereby suppressing the amount of slurry used.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

[0007] However, in the polishing apparatus proposed in Patent Documents 1 and 2, the slurry used for polishing is collected in a container and reattached to the polishing pad, which leads to a problem in that the polishing rate (amount of polishing per unit time) gradually decreases over time.

[0008] Furthermore, when the polishing rate decreases, it becomes necessary to replace the slurry stored in the container with fresh slurry. This means that the slurry cannot reattach to the polishing pad until the required amount of slurry has accumulated in the container, which leads to the problem of longer polishing times.

[0009] Therefore, CMP polishing equipment faces the challenge of reducing slurry consumption and shortening polishing time without causing a decrease in the polishing rate. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides a chuck table that holds a wafer on a holding surface and rotates the wafer around its center as an axis, and the holding surface rotates around a position offset from the rotation center of the held wafer as an axis to cover the upper surface of the wafer. polished surface A CMP polishing apparatus comprising a polishing pad and a slurry supply unit that supplies slurry from the center of the polishing pad to the upper surface of a wafer held by the holding surface, further comprising a non-rotating annular cylinder arranged to surround the polishing pad and a plurality of air nozzles arranged on the inner surface of the annular cylinder that spray air from the lower outer surface of the polishing pad toward the center, characterized in that the slurry scattered radially outward from the outer surface of the polishing pad by the centrifugal force of the rotating polishing pad is received on the inner surface of the annular cylinder, and the slurry is adhered to the polishing pad by air sprayed from the air nozzles opening on the inner surface. If the device includes a crescent-shaped lower plate connected to the lower end of the annular cylinder and facing a crescent-shaped overhang area where a portion of the polishing surface of the polishing pad protrudes from the wafer held on the holding surface, the slurry is made to adhere to the polishing pad by the air sprayed from the air nozzle, flowing along the upper surface of the lower plate. The polishing pad has an area that covers the entire upper surface of the wafer and may include an overhang area. [Effects of the Invention]

[0011] According to the present invention, during wafer polishing with a polishing pad, the slurry supplied to the contact surface between the polishing pad and the wafer and used for polishing the wafer is scattered radially outward by centrifugal force and caught by the inner surface of the annular cylinder. The slurry caught by the inner surface of the annular cylinder is then blown toward the lower surface of the polishing pad by air injected from an air nozzle opening on the inner surface of the annular cylinder, adheres to the lower surface of the polishing pad, and is reused for wafer polishing.

[0012] In this invention, the slurry that is scattered radially outward by the centrifugal force caused by the rotation of the wafer and polishing pad includes material that was not used to polish the wafer. However, in this invention, the slurry, including the material that was previously wasted and not used for polishing, is blown onto the polishing pad with air to be used for polishing the wafer. As a result, the amount of slurry consumed can be reduced without lowering the polishing rate.

[0013] Furthermore, by receiving the scattered slurry on the inner surface of the annular cylinder and blowing this received slurry onto the polishing pad with air to adhere it, the wafer can be continuously polished without replacing the slurry with a new one. As a result, the polishing work can be carried out continuously without interruption, and the polishing time can be shortened. [Brief explanation of the drawing]

[0014] [Figure 1] This is a cross-sectional perspective view of a CMP polishing apparatus according to the first embodiment of the present invention. [Figure 2] It is a broken side view of the main part of the CMP polishing apparatus according to the first embodiment of the present invention. [Figure 3] It is a broken side view showing an enlarged view of the main part of FIG. 2. [Figure 4] It is an enlarged detailed view of part A of FIG. 3. [Figure 5] It is an enlarged detailed view of part B of FIG. 3. [Figure 6] It is a plan view schematically showing the positional relationship of the chuck table, wafer, annular cylinder, and air injection port in the CMP polishing apparatus according to the first embodiment of the present invention. [Figure 7] It is a broken side view of the main part of the CMP polishing apparatus according to the second embodiment of the present invention. [Figure 8] It is a broken side view showing an enlarged view of the main part of FIG. 7. [Figure 9] It is an enlarged detailed view of part C of FIG. 8. [Figure 10] It is a plan view schematically showing the positional relationship of the chuck table, wafer, annular cylinder, and air injection port in the CMP polishing apparatus according to the second embodiment of the present invention. [Figure 11] It is a broken side view showing an enlarged view of the main part of the CMP polishing apparatus according to the third embodiment of the present invention. [Figure 12] It is an enlarged detailed view of part D of FIG. 11. [Embodiments for Carrying Out the Invention]

[0015] [First Embodiment] [Basic Configuration of CMP Polishing Apparatus] The illustrated CMP polishing apparatus 1 is a device for polishing a disc-shaped wafer 100 (see Figures 2, 3, and 6) which is the object to be polished, and comprises a chuck table 10 that holds the wafer 100 on its upper circular holding surface 11, a horizontal movement mechanism 20 that moves the chuck table 10 in the front-back direction (Y-axis direction), a polishing mechanism 30 that polishes the wafer 100 which is held by suction on the holding surface 11 of the chuck table 10, a lifting mechanism 40 that moves the polishing mechanism 30 up and down in the Z-axis direction (up and down direction), a slurry supply unit 50 that supplies slurry to the upper surface of the wafer 100 from the center of the polishing pad 35 of the polishing mechanism 30, and a non-rotating annular cylinder 60 that is arranged to surround the outer circumference of the polishing pad 35.

[0016] Here, wafer 100 is made of a single-crystal silicon matrix, and in the state shown in Figure 1, multiple devices (not shown) are formed on the downward-facing surface, and these devices are protected by protective tape (not shown) attached to the surface of wafer 100. The wafer 100 is held by suction on its surface (bottom surface in Figure 1) to the holding surface 11 of the chuck table 10, and its back surface (top surface in Figure 1) is polished by the polishing pad 35 of the polishing mechanism 30 while receiving slurry from the slurry supply unit 50.

[0017] The chuck table 10 is a disc-shaped member, and a disc-shaped porous member 13 made of porous ceramic or the like is incorporated into a circular recess 12 formed in its center. The upper surface of the porous member 13 constitutes a holding surface 11 that sucks and holds the disc-shaped wafer 100. The porous member 13 is connected to a suction source (not shown), such as a vacuum pump.

[0018] As shown in Figure 2, the chuck table 10 is attached to the upper end of a rotatable base member 14, and the base member 14 is rotatably supported via a bearing 16 on an annular support member 15 fixed to a slider 21. A large-diameter driven pulley 2 is also attached to the outer circumference of the small-diameter lower end of the base member 14.

[0019] Furthermore, a motor 4 is mounted vertically on the slider 21 via a stay 3, and a small-diameter drive pulley 6 is attached to the end of an output shaft (motor shaft) 5 that extends vertically upward from the motor 4. An endless transmission belt 7 is wound between the drive pulley 6 and the driven pulley 2.

[0020] As shown in Figure 1, the CMP polishing apparatus 1 according to this embodiment is equipped with a rectangular box-shaped base 70 that is long in the Y-axis direction (front-to-back direction), and a rectangular block-shaped internal base 71 is housed inside this base 70. A horizontal movement mechanism 20 is provided on this internal base 71 for moving the wafer 100, which is held by suction on the holding surface 11 of the chuck table 10, along the Y-axis direction (front-to-back direction). This horizontal movement mechanism 20 is equipped with a block-shaped slider 21, and this slider 21 is slidable in the Y-axis direction along a pair of left and right guide rails 22 that are arranged parallel to each other along the Y-axis direction (front-to-back direction). Therefore, the chuck table 10 supported by this slider 21 and the rotational drive mechanism including the motor 4 shown in Figure 2 are slidable along the Y-axis direction together with the slider 21.

[0021] A rotatable ball screw shaft 23 extending in the Y-axis direction (front-to-back direction) is positioned between a pair of left and right guide rails 22 on the internal base 71. One end of the ball screw shaft 23 in the Y-axis direction (the left end in Figure 1) is connected to a reversible motor 24, which is the drive source. The other end of the ball screw shaft 23 in the Y-axis direction (the right end in Figure 1) is rotatably supported by a bearing 25 erected on the internal base 71. As shown in Figure 2, a nut member 26 protruding downward from the slider 21 is screwed onto this ball screw shaft 23.

[0022] Therefore, when the motor 24 rotates the ball screw shaft 23 in forward and reverse directions, the nut member 26, which is screwed onto the ball screw shaft 23, slides along the ball screw shaft 23 in the Y-axis direction (forward and backward direction) together with the slider 21. As a result, the chuck table 10 also moves integrally along the Y-axis direction along with the slider 21. Consequently, the wafer 100, which is the workpiece to be polished and is held by suction on the holding surface 11 of the chuck table 10 (see Figures 2 and 3), also moves along the Y-axis direction.

[0023] Furthermore, as shown in Figure 1, a rectangular opening 27, elongated in the Y-axis direction, is formed on the upper surface of the base 70, and the chuck table 10 is housed in this opening 27. The area around the chuck table 10 in the opening 27 that opens on the upper surface of the base 70 is covered by a rectangular plate-shaped cover 28, and the front and rear portions of the cover 28 (in the -Y direction and +Y direction) of the opening 27 are covered by bellows-shaped expandable covers 29 that move and expand together with the cover 28. Therefore, no matter what position the chuck table 10 is in in the Y-axis direction, the opening 27 is covered by the expandable cover 29, preventing foreign matter from entering the interior of the base 70 through the opening 27.

[0024] The polishing mechanism 30 comprises a spindle 31 having a rotational axis in the Z-axis direction, a housing 32 that rotatably supports the spindle 31, a spindle motor 33 that rotationally drives the spindle 31, a mount 34 connected to the lower end of the spindle 31, and a disc-shaped polishing pad 35 detachably attached to the lower surface of the mount 34. The polishing pad 35 is constructed by bonding a disc-shaped pad material 352, such as nonwoven fabric or urethane, to the lower surface of a disc-shaped base 351.

[0025] Here, as shown in Figures 2, 3, and 6, the polishing pad 35 has an area that covers the wafer 100 held on the holding surface 11 of the chuck table 10 (see Figure 1) from above. Specifically, the outer diameter of the polishing pad 35 is preferably set to be larger than the outer diameter of the wafer 100. When polishing the wafer 100, the polishing pad 35 is positioned to cover the upper surface of the wafer 100 and have a crescent-shaped overhang area extending outward from the outer circumference of the wafer 100. The outer diameter of the polishing pad 35 may be set to be larger than the radius of the wafer 100, and may have an area that covers at least the radial portion of the wafer 100 from above and has a crescent-shaped overhang area extending outward from the outer circumference of the wafer 100.

[0026] As shown in Figure 1, a rectangular box-shaped column 72 is erected vertically on the +Y-axis end (rear end) of the upper surface of the base 70, and a lifting mechanism 40 is provided on the -Y-axis end face (front) of this column 72. This lifting mechanism 40 moves the polishing mechanism 30 up and down in a direction perpendicular to the holding surface 11 of the chuck table 10 (Z-axis direction), and moves a rectangular plate-shaped lifting plate 41 attached to the back of the housing 32 up and down in the Z-axis direction along a pair of left and right guide rails 42, together with the housing 32 and the spindle 31, spindle motor 33, polishing pad 35, etc. held in the housing 32. Here, the pair of left and right guide rails 42 are arranged perpendicular and parallel to each other on the front surface of the column 72.

[0027] As shown in Figure 1, a rotatable ball screw shaft 43 is erected vertically along the Z-axis direction (up and down direction) between a pair of left and right guide rails 42, and the upper end of the ball screw shaft 43 is connected to a motor 44 that can rotate in both forward and reverse directions, which is the drive source. The lower end of the ball screw shaft 43 is rotatably supported by a bearing 45 on a column 72, and as shown in Figure 2, a nut member 46 that protrudes horizontally toward the rear (+Y-axis direction) from the back of the lifting plate 41 is screwed onto this ball screw shaft 43.

[0028] The slurry supply unit 50 supplies slurry from the center of the polishing pad 35 of the polishing mechanism 30 to the upper surface of the wafer 100. As shown in Figure 2, it supplies slurry from the slurry supply source 51 to the upper surface of the wafer 100 via a small-diameter first supply passage 52 that runs vertically through the axis centers of the spindle motor 33, spindle 31, and mount 34, and a large-diameter second supply passage 53 that runs vertically through the axis center of the polishing pad 35. Here, the first supply passage 52 and the second supply passage 53 are in communication with each other, and the second supply passage 53 opens to the lower end surface of the polishing pad 35. The upper end of the first supply passage 52 is connected to the slurry supply source 51 via a rotary joint 54.

[0029] As described above, the annular cylinder 60 is a non-rotating, two-stage cylindrical member of different diameters, arranged to surround the outer circumference of the polishing pad 35. The first cylindrical portion 61 on the smaller diameter side and the second cylindrical portion 62 on the larger diameter side located below it are connected by a horizontal annular upper plate 63 to form a single unit. As shown in Figures 2 and 3, the upper end of the annular cylinder 60 is attached to the lower end of the housing 32 by multiple bolts 9 (only two are shown in Figures 2 and 3) via an annular fixing member 8, and the second cylindrical portion 62 opens downward in a circular hole shape.

[0030] As shown in Figure 6, the annular cylinder 60 is divided into two parts: a first cylindrical portion 601 located in a short arc-shaped first region R1 close to the wafer 100 and polishing pad 35, and a second cylindrical portion 602 located in a long arc-shaped region R2 far from the wafer 100 and polishing pad 35. As shown in Figures 2, 3, and 6, the first cylindrical portion 601, the second cylindrical portion 602, and the fixing member 8 have multiple crank-shaped first air passages 64 and second air passages 65 formed at equal angular pitches in the circumferential direction. As shown in Figures 4 and 5, these first and second air passages 64 and 65 open as air injection ports 641 and 651, respectively, on the inner circumferential surface of the annular cylinder 60 (first cylindrical portion 601 and second cylindrical portion 602).

[0031] Here, as shown in Figures 2 and 3, the height of the second cylindrical portion 62 is set higher than the height of the first cylindrical portion 61, and the lower end of the second cylindrical portion 62 extends below the lower surface of the polishing pad 35. The air nozzle 641 of the first air passage 64 formed in the first cylindrical portion 601 of the annular cylinder 60 opens horizontally toward the lower surface of the polishing pad 35, as shown in Figure 4, and the air nozzle 651 of the second air passage 65 formed in the second cylindrical portion 602 opens at an angle upward toward the lower surface of the polishing pad 35, as shown in Figure 5.

[0032] As shown in Figure 2, the annular cylinder 60 and the multiple first air passages 64 and second air passages 65 formed in the fixing member 8 are connected to an air source 68 such as a compressor via a joint 66 and an air pipe 67.

[0033] [Operation and Effects of CMP Polishing Equipment] Next, we will describe the polishing process of the wafer 100 using the CMP polishing apparatus 1 configured as described above.

[0034] When polishing the wafer 100, the wafer 100 is placed face down on the holding surface 11 of the chuck table 10. Then, when a suction source (not shown) is driven to create a vacuum in the porous member 13, negative pressure is generated in the porous member 13, and the wafer 100 placed on the holding surface 11 is attracted and held on the holding surface 11 by the negative pressure.

[0035] From the above state, the horizontal movement mechanism 20 shown in Figure 1 is driven to move the chuck table 10 in the +Y axis direction (rearward), positioning the wafer 100, which is held by suction on the chuck table 10, below the polishing pad 35 of the polishing mechanism 30. That is, when the motor 24 is started and the ball screw shaft 23 rotates, the slider 21, to which a nut member 26 that is screwed onto the ball screw shaft 23 is attached, slides along the pair of left and right guide rails 22 in the +Y axis direction together with the chuck table 10, etc., so that the wafer 100 held on the holding surface 11 of the chuck table 10 is positioned below the polishing pad 35 of the polishing mechanism 30.

[0036] Furthermore, the motor 4 shown in Figure 2 is driven to rotate the chuck table 10 at a predetermined rotational speed (for example, 300 rpm) in the direction of arrow 10a (counterclockwise) in Figure 6. That is, when the motor 4 is driven, the rotation of the output shaft 5 of the motor 4 is transmitted to the base member 14 and the chuck table 10 via the drive pulley 6, the transmission belt 7 and the driven pulley 2, and the wafer 100 held on the holding surface 11 of the chuck table 10 is driven to rotate at a predetermined speed. At the same time, the spindle motor 33 of the polishing mechanism 30 is started to rotate the polishing pad 35 at a predetermined speed (for example, 1000 rpm) in the direction of arrow 35a (counterclockwise, the same direction as the rotation of the wafer 100) in Figure 6.

[0037] As described above, with the wafer 100 and polishing pad 35 rotating, the lifting mechanism 40 is driven to lower the polishing pad 35 in the -Z axis direction. That is, when the motor 44 is driven and the ball screw shaft 43 rotates, the lifting plate 41, which is provided with a nut member 46 that screws onto the ball screw shaft 43, descends in the -Z axis direction together with the housing 32 and the polishing pad 35. As a result, the lower surface (polishing surface) of the polishing pad 35 comes into contact with the entire upper surface (back surface) of the wafer 100. At this time, slurry is supplied from the slurry supply source 51 shown in Figure 2 to the contact surface between the polishing pad 35 and the wafer 100 from the first supply passage 52 which penetrates the axis centers of the spindle motor 33, spindle 31 and mount 34, and the second supply passage 53 which penetrates the axis center of the polishing pad 35. As a result, the chemical action of the slurry and the mechanical action of the polishing pad 35 work together to polish the upper surface of the wafer 100, removing any remaining grinding marks and increasing the flexural strength of the wafer 100.

[0038] Furthermore, during the polishing process of the wafer 100, high-pressure air is supplied from the air source 68 shown in Figure 2 through the air piping 67 to a plurality of first and second air passages 64 and 65, respectively. This air is then sprayed toward the lower surface of the polishing pad 35 from a plurality of air nozzles 641 and 651 that open to the inner circumferential surfaces of the first cylindrical portion 601 and the second cylindrical portion 602, respectively.

[0039] During the polishing of the wafer 100 by the polishing pad 35, the slurry supplied to the contact surface between the polishing pad 35 and the wafer 100 and used for polishing the wafer 100, as well as the slurry that was not used for polishing, are scattered radially outward by centrifugal force and caught by the annular cylinder 60 (first cylindrical section 601 and second cylindrical section 602). The slurry caught on the inner surface of the annular cylinder 60 is then blown toward the lower surface of the polishing pad 35 by air injected from a plurality of air injection ports 641, 651 opening on the inner surface of the annular cylinder 60 (first cylindrical section 601 and second cylindrical section 602), respectively, and adheres to the lower surface of the polishing pad 35, where it is reused for polishing the wafer 100.

[0040] The slurry that is scattered radially outward by the centrifugal force generated by the rotation of the wafer 100 and the polishing pad 35 includes some that was not used to polish the wafer 100. However, in this embodiment, the slurry, including the parts that were not used for polishing which were previously wasted, is blown onto the polishing pad 35 with air and used to polish the wafer 100. As a result, the amount of slurry consumed can be reduced without lowering the polishing rate.

[0041] Furthermore, by receiving the scattered slurry on the inner surface of the annular cylinder 60 and blowing this received slurry onto the polishing pad 35 with air to adhere it, the slurry can be continuously used to polish the wafer 100 without replacing it with a new one. As a result, the polishing work can be carried out continuously without interruption, and the polishing time can be shortened.

[0042] Furthermore, it is possible to increase the slurry's concentration by heating the air and blowing hot air onto the slurry to evaporate the moisture, or conversely, to decrease the slurry's concentration by blowing cold air onto the slurry.

[0043] <Second Embodiment> Next, a second embodiment of the present invention will be described below with reference to Figures 7 to 10.

[0044] Since the basic configuration of the CMP polishing apparatus according to this embodiment is the same as that of the CMP polishing apparatus 1 according to the first embodiment, only the characteristic configuration of this embodiment will be described. Accordingly, in Figures 7 to 10, the same reference numerals are used for elements that are the same as those shown in Figures 1 to 6, and further explanation of them will be omitted below.

[0045] In this embodiment, as shown in Figures 7 and 8, the lower end of the second cylindrical portion 602 of the annular cylinder 60 is bent at a right angle inward (to the left in Figures 7 and 8) along the lower end surface of the polishing pad 35 to form a lower plate 69, and multiple air passages 691 are formed radially toward the polishing pad 35 on this lower plate 69 (see Figure 10).

[0046] Here, as shown in Figure 10, the lower plate 69 formed in the second cylindrical portion 602 of the annular cylinder 60 is formed in a crescent shape so as to face the crescent-shaped overhang area R where the polishing pad 35 extends beyond the wafer 100 held on the holding surface 11 of the chuck table 10. The inner circumferential surface of this lower plate 69 is an arc-shaped curved surface that follows the outer circumference of the polishing pad 35, and a plurality of air passages 691 open on this inner circumferential surface as air nozzles 691a. Here, as shown in Figure 9, the plurality of air nozzles 691a open at an angle upward toward the lower surface of the polishing pad 35. The air nozzles 641 of the plurality of first air passages 64 formed in the first cylindrical portion 601 open horizontally along the lower surface of the polishing pad 35 (see Figure 4).

[0047] In the CMP polishing apparatus according to this embodiment, similar to the CMP polishing apparatus 1 according to the first embodiment, the wafer 100 is polished while a slurry is supplied. However, the slurry supplied to the contact surface between the polishing pad 35 and the wafer 100 and used to polish the wafer 100, as well as the slurry that was not used for polishing, are scattered radially outward by the centrifugal force caused by the rotation of the wafer 100 and the polishing pad 35, and are caught by the annular cylinder 60 (first cylindrical portion 601 and second cylindrical portion 602).

[0048] The slurry received by the inner circumferential surface of the first cylindrical portion 601 of the annular cylinder 60 is blown by air injected from the air injection port 641 toward the corners between the side and bottom surfaces of the polishing pad 35 and toward the outer circumference of the wafer 100, preventing the slurry from adhering to the outer edge of the wafer 100. The slurry is blown along the outer circumference of the wafer 100, causing it to adhere to the bottom surface of the polishing pad 35 and continue to be used for polishing the wafer 100. The slurry received by the inner circumferential surface of the second cylindrical portion 602 falls along the inner circumferential surface of the second cylindrical portion 602 and is received by the upper surface of the lower plate 69. The slurry, received by the upper surface of the lower plate 69, is drawn by the negative pressure generated by the air jets from multiple air jets 691a opening on the inner circumferential surface of the lower plate 69 toward the polishing pad 35, and flows along the upper surface of the lower plate 69 toward the polishing pad 35. As it falls from the arc-shaped inner edge along the outer circumference of the polishing pad 35 of the lower plate 69, it is blown toward the lower surface of the polishing pad 35 by the air jets 6911, adheres to the lower surface of the polishing pad 35, and continues to be used for polishing the wafer 100.

[0049] Therefore, in this embodiment as well, similar to the first embodiment, the slurry, including material that was previously wasted and not used for polishing, is blown onto the polishing pad 35 with air and used for polishing the wafer 100. As a result, the amount of slurry consumed can be reduced without lowering the polishing rate.

[0050] Furthermore, by receiving the scattered slurry on the inner surface of the annular cylinder 60 and blowing this received slurry onto the polishing pad 35 with air to adhere it, the slurry can be continuously used to polish the wafer 100 without replacing it with a new one. As a result, the polishing work can be carried out continuously without interruption, and consequently, the polishing time can be shortened.

[0051] <Third Embodiment> Next, a third embodiment of the present invention will be described below with reference to Figures 11 and 12.

[0052] The polishing pad 35a shown in Figure 11 is formed to be smaller in diameter than the wafer 100, and the overhang area R shown in Figures 6 and 10 is not formed. The non-rotating annular cylinder 60a surrounding the polishing pad 35a is integrally constructed by connecting a large-diameter first cylindrical portion 61a and a second cylindrical portion 62a located below it and smaller in diameter than the first cylindrical portion 61a with a horizontal annular upper plate 63a. The upper end of this annular cylinder 60a is attached to the lower end of the housing 32 by multiple bolts 9 (only two are shown in Figure 11) via an annular fixing member 8, and the second cylindrical portion 62a opens downward in a circular hole shape.

[0053] The lower end of the second cylindrical portion 62a is located slightly above the lower surface of the polishing pad 35a. As shown in Figure 12, the air nozzle 641a of the air passage 64a formed in the second cylindrical portion 62a opens horizontally toward the side surface of the pad material 352a of the polishing pad 35a.

[0054] During the polishing of the wafer 100, the slurry supplied to the contact surface between the polishing pad 35a and the wafer 100 and used for polishing the wafer 100, as well as the slurry that was not used for polishing, are scattered radially outward by the centrifugal force caused by the rotation of the wafer 100 and the polishing pad 35a. On the other hand, an annular air layer is formed around the polishing pad 35a by the air sprayed from the air nozzle 641a. This air layer prevents the slurry from being discharged outside the annular cylinder 60a, while the rotation of the wafer 100 causes the slurry to enter the underside of the pad material 352a of the polishing pad 35a, allowing the wafer 100 to be polished with a small amount of slurry without reducing the polishing rate.

[0055] Furthermore, since the slurry can be continuously used to polish wafer 100 without being replaced with a new one, the polishing process can be carried out continuously without interruption, resulting in a reduction in polishing time.

[0056] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the technical idea described in the claims, specification, and drawings. [Explanation of Symbols]

[0057] 1: CMP polishing and grinding equipment, 2: driven pulley, 3: stay, 4: motor, 5: Output shaft, 6: Drive pulley, 7: Transmission belt, 8: Fixing member, 9: Bolt, 10: Chuck table, 11: Holding surface, 12: Recess, 13: Porous member, 14: Base member, 15: Support member, 16: Bearing, 17: Motor, 18: Output shaft, 20: Horizontal movement mechanism, 21: Slider, 22: Guide rail, 23: Ball shaft, 24: Motor, 25: Bearing, 26: Nut component, 27: Opening, 28: Cover, 29: Extendable cover, 30: Polishing mechanism, 31: Spindle, 32: Housing, 33: Spindle motor, 34: Mount, 35, 35a: Polishing pad, 351, 351a: base, 352, 352a: pad material, 40: lifting mechanism, 41: Lifting plate, 42: Guide rail, 43: Ball screw shaft, 44: Motor, 45: Bearing, 46: Nut component, 50: Slurry supply unit, 51: Slurry supply source, 52: First supply path, 53: Second supply channel, 54: Rotary joint, 60, 60a: Annular cylinder, 601: First cylinder part, 602: Second cylinder part, 61, 61a: First cylindrical section, 62, 62a: Second cylindrical section, 63, 63a: Upper plate, 64, 64a: First air passage, 641, 641a: Air nozzle, 65: Second air passage, 651: Air nozzle, 66: Joint, 67: Air piping, 68: Air source, 69: Bottom plate, 691: Air passage, 6911: Air nozzle, 70: Base, 71: Internal base, 72: Column, 100: Wafer, R: Overhang area, R1: First area, R2: 2nd area

Claims

1. A CMP polishing apparatus comprising: a chuck table that holds a wafer on a holding surface and rotates the wafer about its center as an axis; a polishing pad that rotates about an axis offset from the rotation center of the wafer held by the holding surface to polish the upper surface of the wafer with a polishing surface; and a slurry supply unit that supplies slurry from the center of the polishing pad to the upper surface of the wafer held by the holding surface, The device comprises a non-rotating annular cylinder positioned to surround the polishing pad, and a plurality of air nozzles arranged on the inner circumferential surface of the annular cylinder, which spray air from the lower outer surface of the polishing pad toward the center. A CMP polishing apparatus that collects the slurry scattered radially outward from the outer circumference of the polishing pad by the centrifugal force of the rotating polishing pad on the inner surface of the annular cylinder, and adheres the slurry to the polishing pad by air injected from an air nozzle opening on the inner surface.

2. The CMP polishing apparatus according to claim 1, comprising a crescent-shaped lower plate connected to the lower end of the annular cylinder and facing a crescent-shaped overhang area where a portion of the polishing surface of the polishing pad protrudes from the wafer held on the holding surface, wherein air sprayed from the air nozzle causes the slurry to travel along the upper surface of the lower plate and adhere to the polishing pad.

3. The CMP polishing apparatus according to claim 2, wherein the polishing pad has an area that covers the entire upper surface of the wafer and includes an overhang area.

Images