Polishing head, polishing device and polishing method

Abstract

To provide a polishing head, a polishing device and a polishing method which enable one polishing head to perform front-face reference polishing and rear-face reference polishing and can reduce downtime, reduce facility costs and downsize and simplify a facility, and further prevent an adsorption mark from remaining on a work-piece and a foreign matter from mixing in the polishing head.SOLUTION: A polishing head 12 comprises: a backing material 48 having an adsorption surface 48a corresponding to an upper surface of a work-piece W and a press surface 48b at the opposite side of the adsorption surface; a work-piece pressurizing plate 36 at a center part of the press surface 48b; and a first fluid chamber 50 arranged between the work-piece pressurizing plate 36 and the backing material 48. A control part 72 switches between front-face reference polishing which the inside of the first fluid chamber 50 is pressurized to polish the work-piece W with the work-piece pressurizing plate 36 separated from the backing material 48 and rear-face reference polishing which the inside of the first fluid chamber 50 is vacuumized or opened to the atmosphere and downward force is applied to the work-piece pressurizing plate 36 to polish the work-piece W with the work-piece pressurizing plate 36 contacted with the backing material 48.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a polishing head, a polishing apparatus, and a polishing method. [Background technology]

[0002] In a polishing apparatus, a polishing head is known that is provided to be movable up and down and rotatable, and holds and rotates a workpiece while pressing it against a polishing pad to polish it. Also, a polishing apparatus is known in which a workpiece held on the lower surface of the polishing head provided above a base plate is pressed against a polishing pad attached to the upper surface of the base plate, and the base plate and the polishing head are rotated to slide relative to each other to polish the workpiece. The polishing apparatus is a single-sided polishing apparatus that polishes one side of the workpiece.

[0003] As described in Patent Document 1 (Patent Publication No. 5629594), there are usually two polishing methods for polishing using a single-sided polishing device (see Patent Document 1: Figure 5). One is back-side reference polishing, which is a method in which the back side of the workpiece (the upper surface, which is the surface not to be polished) is fixed to a relatively hard and flat surface and polished. In this case, the front side of the workpiece (the lower surface, which is the polished surface) is polished according to the shape of the back side, i.e., the shape of the above-mentioned flat surface of the polishing head. On the other hand, the other is front-side reference polishing, which is a method in which the back side of the workpiece is fixed to a relatively soft elastic surface and polished. In this case, the front side of the workpiece is polished according to the shape of the front side. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5629594 Summary of the Invention [Problem to be solved by the invention]

[0005] The workpiece is polished by using either front surface reference polishing or back surface reference polishing depending on the purpose.

[0006] However, since the conventional polishing heads for performing front surface reference polishing and back surface reference polishing have different basic configurations, it was necessary to replace the polishing head or install multiple polishing devices according to each polishing method, which resulted in problems such as downtime due to the replacement of the polishing head, increased equipment costs due to the use of multiple polishing heads or polishing devices, and larger and more complicated equipment.

[0007] In addition, in conventional polishing heads (polishing devices), when the back surface of a workpiece is fixed to a relatively soft elastic surface, the soft material is formed porous as suction holes, through which air is sucked in to suction and fix the workpiece. Therefore, there is a risk of suction marks being left on the workpiece when the workpiece is fixed or picked up. In addition, there is a risk that water, slurry, and other foreign matter may be sucked into the polishing head together with air through the suction holes during pickup, causing malfunction of the polishing head. [Means for solving the problem]

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a polishing head, polishing device, and polishing method that can perform both front surface reference polishing and back surface reference polishing with a single polishing head, reduce downtime, reduce equipment costs, and make the equipment smaller and simpler, and further prevent suction marks on the workpiece and the intrusion of foreign matter into the polishing head.

[0009] The present invention solves the above problems by the solution means described below as one embodiment.

[0010] The polishing head according to the present invention is a polishing head that is fixed to a head shaft that is movable up and down and rotatable, and that holds and rotates a workpiece while pressing it against a polishing pad to polish it. The polishing head comprises a backing material having an adsorption surface that faces the upper surface of the workpiece and a press surface on the opposite side of the adsorption surface, a workpiece pressure plate that is movable up and down and is provided in the center of the press surface so as to be able to approach and separate from the press surface, a first fluid chamber provided between the workpiece pressure plate and the backing material, and a first pressure adjustment mechanism that adjusts the pressure in the first fluid chamber, and a control unit controls the pressurization in the first fluid chamber to adjust the pressure in the first fluid chamber. The present invention is characterized by controlling the control to switch between front surface reference polishing, in which the workpiece is pressed from above while the lower surface of the work pressure plate and the press surface of the backing material are separated and the upper surface of the workpiece and the suction surface of the backing material are in contact, and back surface reference polishing, in which the workpiece is pressed from above while the lower surface of the work pressure plate and the press surface of the backing material are in contact and the upper surface of the workpiece and the suction surface of the backing material are in contact, by making the first fluid chamber a vacuum or opening it to the atmosphere and controlling the application of a downward force to the work pressure plate.

[0011] This allows both front surface reference polishing and back surface reference polishing to be performed with one polishing head. Also, since the workpiece pressure plate can be separated from the backing material to form a gap, the backing material can be used as a suction cup to fix and pick up the workpiece. Therefore, there is no need to provide suction holes in the backing material, and as a result, suction marks on the workpiece and the intrusion of foreign matter into the polishing head can be prevented.

[0012] In addition, the polishing head of the present invention further includes a retainer provided on the outer periphery of the suction surface, and a retainer pressure unit provided on the outer periphery of the press surface and capable of moving up and down, and the control unit applies forces in opposite directions relative to the retainer pressure unit and the work pressure plate, so that in the front surface reference polishing, polishing is performed in a state where the lower end surface of the work pressure plate is positioned relatively higher than the lower end surface of the retainer pressure unit, and in the back surface reference polishing, polishing is performed in a state where the lower end surface of the work pressure plate and the lower end surface of the retainer pressure unit are horizontally aligned, or the lower end surface of the work pressure plate is positioned relatively lower than the lower end surface of the retainer pressure unit.

[0013] In addition, it is preferable that the polishing head of the present invention is provided with a pressing portion that abuts the work pressure plate and the retainer pressure portion to fix them relative to each other, and that the pressing portion functions as a stopper that regulates the movement of the work pressure plate and the retainer pressure portion in a predetermined direction when polishing the work, thereby creating a relative positional relationship.

[0014] As an example of the positional relationship, a gap may be formed between the retainer and the polishing pad when the workpiece is pressed against the polishing pad with the workpiece pressure plate and the retainer pressure portion in contact with each other via the pressing portion during the backside reference polishing. This makes it possible to prevent contact between the retainer and the polishing pad during the backside reference polishing and to prevent wear of the retainer.

[0015] Moreover, it is preferable that the workpiece pressure plate is composed of two layers consisting of an upper plate and a lower plate, and further includes a second fluid chamber between the upper plate and the lower plate, and a second pressure adjustment mechanism for adjusting the pressure in the second fluid chamber, and the lower plate has a flow path that communicates the first fluid chamber and the second fluid chamber. According to this, when the workpiece pressure plate and the backing material are brought into contact with each other and integrated during the back surface reference polishing, the second fluid chamber is evacuated, so that air bubbles between the workpiece pressure plate and the backing material can be removed from the flow path through the second fluid chamber, thereby further improving the adhesion between them. As an example, the flow path can be formed by making the lower plate from a porous material.

[0016] Alternatively, the workpiece pressure plate preferably has a passage that communicates the first fluid chamber with the first passage in which the first pressure adjustment mechanism is provided. With this, when the workpiece pressure plate and the backing material are brought into contact with each other and integrated during back surface reference polishing, the first fluid chamber is evacuated, so that air bubbles between the workpiece pressure plate and the backing material can be removed from the passage through the first passage, thereby further improving the adhesion between them. As an example, the passage can be formed as a groove on the lower surface of the workpiece pressure plate.

[0017] Alternatively, it is preferable that the workpiece pressure plate has a passage that communicates with the first fluid chamber and a fifth passage in which a fifth pressure adjustment mechanism is provided, and the fifth pressure adjustment mechanism is configured to be able to evacuate at least the passage through the fifth passage. According to this, when the workpiece pressure plate and the backing material are brought into contact with each other and integrated during the back surface reference polishing, the passage is evacuated through the fifth passage by the fifth pressure adjustment mechanism, so that air bubbles between the workpiece pressure plate and the backing material can be removed from the passage through the fifth passage, thereby further improving the adhesion between them.

[0018] The polishing head according to the present invention may further include a head base portion fixed to the head shaft, the work pressure plate is fixed to the head base portion and moves up and down by driving the head shaft, and the control portion may be configured to control the application of a downward force to the work pressure plate by applying a driving force to lower the work pressure plate via the head shaft during the back surface reference polishing. Alternatively, the polishing head according to the present invention may further include a head base portion fixed to the head shaft, the work pressure plate is suspended or slidably attached to the head base portion, and moves up and down by adjusting the pressure in a third fluid chamber provided between the head base portion and the work pressure plate by a third pressure adjustment mechanism, and the control portion may be configured to control the application of a downward force to the work pressure plate by pressurizing the third fluid chamber during the back surface reference polishing.

[0019] A polishing apparatus according to the present invention is characterized by including the polishing head according to the present invention.

[0020] In addition, a polishing method according to the present invention is a polishing method in which a workpiece held by a polishing head is pressed against a polishing pad to be polished, the polishing head including a backing material having an adsorption surface facing the upper surface of the workpiece and a press surface opposite the adsorption surface, and a workpiece pressure plate provided in the center of the press surface so as to be able to approach and separate from the press surface and capable of moving up and down, the polishing method being characterized in that it switches between front surface reference polishing in which the workpiece is pressed from above in a state in which the lower surface of the workpiece pressure plate and the press surface of the backing material are separated and the upper surface of the workpiece and the adsorption surface of the backing material are brought into contact by raising the workpiece pressure plate to form an enclosed space between the backing material and the workpiece pressure plate and pressurizing the enclosed space, and back surface reference polishing in which the workpiece is pressed from above in a state in which the lower surface of the workpiece pressure plate and the press surface of the backing material are brought into contact and the upper surface of the workpiece and the adsorption surface of the backing material are brought into contact by opening the enclosed space to a vacuum or the atmosphere and applying a downward force to the workpiece pressure plate.

[0021] In addition, by using the polishing head further including a retainer provided on the outer periphery of the suction surface and a retainer pressure section provided on the outer periphery of the press surface and capable of moving up and down, in the front surface reference polishing, the retainer pressure section can be lowered to press the polishing pad around the workpiece with the retainer, and in the back surface reference polishing, a gap can be formed between the lower end surface of the retainer and the polishing pad. Effect of the Invention

[0022] According to the present invention, both front surface reference polishing and back surface reference polishing can be performed with one polishing head. This can reduce downtime, reduce equipment costs, and simplify the size of the equipment. In addition, since the workpiece pressure plate can be separated from the backing material to form a gap, the backing material can be used as a suction cup to fix and pick up the workpiece. This eliminates the need to provide suction holes in the backing material, and as a result, it is possible to prevent suction marks on the workpiece and the intrusion of foreign matter into the polishing head. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a schematic view (front view) showing an example of a polishing head according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic view (front sectional view) showing an example of a polishing head according to an embodiment of the present invention, illustrating an example of a state during surface-reference polishing. [Diagram 3] FIG. 2 is a schematic view (front sectional view) showing an example of a polishing head according to an embodiment of the present invention, illustrating an example of a state during back surface reference polishing. [Figure 4] 4 is a schematic view (front sectional view) showing another example of the polishing head shown in FIG. [Diagram 5] 4 is a schematic view (front sectional view) showing another example of the polishing head shown in FIG. [Figure 6] 4 is a schematic view (front sectional view) showing another example of the polishing head shown in FIG. [Figure 7] 3 is a schematic view (front sectional view) showing another example of the polishing head shown in FIG. 2. [Figure 8] 3 is a schematic view (front sectional view) showing another example of the polishing head shown in FIG. 2. [Figure 9] 3 is a schematic view (front sectional view) showing another example of the polishing head shown in FIG. 2. [Figure 10] 4 is an explanatory diagram for explaining an example of surface finishing processing of the polishing head shown in FIG. 3. [Figure 11] 11A is an explanatory diagram for explaining an example of a polishing method according to the present embodiment, and FIG 11B and FIG 11C are explanatory diagrams for explaining the back surface reference polishing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] (Polishing head) Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram (front view) showing an example of the polishing head 12 according to this embodiment. Also, FIG. 2 and FIG. 3 are schematic diagrams (front cross-sectional views) showing an example of the polishing head 12 according to this embodiment. Of these, FIG. 2 shows an example of a state during front surface reference polishing, and FIG. 3 shows an example of a state during back surface reference polishing, but the configurations are the same. Therefore, for the explanation of the configuration, refer to FIG. 1 and FIG. 3, and also refer to FIG. 2 as appropriate. Also, FIG. 4 to FIG. 9 are schematic diagrams (front cross-sectional views) showing other examples of the polishing head 12 according to this embodiment, and these drawings will also be referred to as appropriate. Of these, FIG. 4 to FIG. 6 show other examples of the polishing head 12 shown in FIG. 3, and FIG. 7 to FIG. 9 show other examples of the polishing head 12 shown in FIG. 2. Note that, since the polishing head 12 is a device of the polishing device 10, FIG. 1 to FIG. 9 are also schematic diagrams of the polishing device 10 according to this embodiment, showing peripheral members such as the surface plate 14 and the polishing pad 16.

[0025] 1 and 3, the polishing head 12 according to this embodiment has the function of vertically moving and rotating the workpiece W with its polishing surface Wa facing downward while holding it horizontally on its lower surface, and in the polishing apparatus 10, while rotating the workpiece W, presses it from above against a polishing pad 16 attached to the upper surface of a base 14 rotating in a horizontal plane, thereby polishing the polishing surface Wa of the workpiece W. The workpiece W is a flat (particularly disc-shaped) object to be polished, made of, for example, a semiconductor material or a glass material. The polishing surface Wa of the workpiece W is the front surface Wa, which corresponds to the lower surface Wa, and the non-polished surface Wb of the workpiece W is the back surface Wb, which corresponds to the upper surface Wb.

[0026] The polishing head 12 has a head base part 20 at its upper part. The head base part 20 has a disk-shaped head base top plate part 20a, a cylindrical head upper side wall part 20b protruding downward from the outer end part of the head base top plate part 20a, and a shaft part 20c protruding downward from the center part of the lower surface of the head base top plate part 20a. As a result, the head base part 20 protects the upper part of the polishing head 12 by covering it with a lid. In addition, the center part of the upper surface (upper surface of the head base top plate part 20a) of the head base part 20 is fixed to a head shaft 18 that can move up and down and rotate. The head shaft 18 moves up and down by a vertical movement drive mechanism (not shown) of the drive part. Therefore, the head base part 20 moves up and down together with the head shaft 18. In addition, the head shaft 18 rotates around its axis by a rotation drive mechanism (not shown) of the drive part. Therefore, the head base part 20 rotates around the head shaft 18. Thus, the polishing head 12 is provided so as to be movable up and down and rotatable by driving the head shaft 18. The up and down movement drive mechanism and the rotation drive mechanism of the drive unit can both be constructed of known mechanisms. Specific examples will be described later.

[0027] Next, as shown in Fig. 1 and Fig. 3, the polishing head 12 is provided with a retainer pressure part 22 at its lower part (below the head base part 20). The retainer pressure part 22 is provided with a retainer pressure top plate part 22a located inside the polishing head 12 and below the head base top plate part 20a, a head lower side wall part 22b protruding downward from the outer end part of the retainer pressure top plate part 22a, and a widening part 22c that expands to a predetermined width on the inner circumferential side on the lower surface of the head lower side wall part 22b. As a result, the retainer pressure part 22 protects the lower outer periphery of the polishing head 12 by having the head lower side wall part 22b cover it. In addition, a retainer 24 that presses the polishing pad 16 around the workpiece W is provided on the lower surface (lower surface of the widening part 22c) of the retainer pressure part 22 with a backing material 48 described later sandwiched therebetween.

[0028] 3, the retainer pressure section 22 (retainer pressure top plate section 22a) is suspended on the inner periphery side via a suspension member 26a from the outer periphery of the shaft section 20c of the head base section 20. Also, on the outer periphery side, the retainer pressure section 22 is suspended on the inner periphery of the head upper side wall section 20b of the head base section 20 via a suspension member 26b. These suspension members 26a and 26b may be integrally formed as shown in FIG.

[0029] In this manner, the retainer pressure applying portion 22 is suspended from the head base portion 20 via the suspending members 26a and 26b. The suspending members 26a and 26b according to this embodiment are both formed from diaphragms made of a rubber material, and the retainer pressure applying portion 22 is configured to move up and down with respect to the head base portion 20 via changes in the shape of the suspending members 26a and 26b. When the head base portion 20 rotates, the rotational force is transmitted via the suspending members 26a and 26b, causing the head base portion 20 to rotate. The suspending members 26a and 26b are not limited in configuration or material as long as they can suspend the retainer pressure applying portion 22 so that it can move up and down as described above. That is, they are not limited to diaphragms, and may be, for example, bellows. They are also not limited to rubber materials, and may be resin materials, metal materials, or the like.

[0030] Here, a fourth fluid chamber 28 is provided between the lower surface of the head base portion 20 (the lower surface of the head base top plate portion 20a) and the upper surface of the retainer pressurizing portion 22 (the upper surface of the retainer pressurizing top plate portion 22a) (and the hanging members 26a, 26b). A fluid can be supplied to and discharged from the fourth fluid chamber 28 through a fourth flow path 30 in which a fourth pressure adjustment mechanism 32 is provided. This allows the retainer pressurizing portion 22 (retainer 24) to be lowered by creating a positive pressure in the fourth fluid chamber 28 formed as a sealed space, or the retainer pressurizing portion 22 (retainer 24) to be raised by creating a negative pressure in the fourth fluid chamber 28. In this embodiment, the fluid is air, and the air pressure in the fourth fluid chamber 28 is adjusted, but this is not limited to this configuration, and the fluid may be water, oil, or the like. The fourth flow path 30, which is composed of a supply path and a discharge path, may be provided as the same pipe line or as separate pipe lines. That is, the number of pipes constituting the fourth flow path 30 and other forms are not limited. The fourth pressure adjustment mechanism 32 is exemplified by a fluid compressor or a solenoid valve, and is driven and controlled by a control unit 72. The control unit 72 provided at a predetermined location in the polishing apparatus 10 is composed of a CPU and a memory, and performs a predetermined operation based on a preset operation program and / or a setting signal input from an operation unit (not shown). A plurality of fourth pressure adjustment mechanisms 32 may be provided.

[0031] In this way, by adjusting the pressure in the fourth fluid chamber 28, the retainer pressurizing portion 22 moves up and down, and the vertical position of the retainer 24 can be adjusted. Therefore, when the workpiece W is polished (when the front surface is polished), the retainer 24 is lowered to press the polishing pad 16 around the workpiece W, thereby preventing over-polishing of the edge of the workpiece W and otherwise affecting the polished shape of the workpiece W, and the so-called retainer effect can be provided, and the pressing force can be adjusted as desired. On the other hand, even when the workpiece W is polished (when the back surface is polished), the retainer 24 is lowered to press the polishing pad 16 around the workpiece W, thereby preventing over-polishing of the edge of the workpiece W and otherwise affecting the polished shape of the workpiece W, and the so-called retainer effect can be provided. In addition, a gap can be generated between the retainer 24 and the polishing pad 16 to prevent wear of the retainer 24.

[0032] As another example, as shown in Fig. 5, the retainer pressure unit 22 (retainer pressure top plate 22a) may be provided in slidable contact with the shaft 20c and the head upper side wall 20b of the head base unit 20 via seal members 34a and 34b such as O-rings, respectively, instead of the hanging members 26a and 26b. The "contact" here requires that the retainer pressure unit 22 is in close contact with the head base unit 20 to such an extent that the retainer pressure unit 22 can slide up and down relative to the head base unit 20 by adjusting the pressure in the fourth fluid chamber 28 with the fourth pressure adjustment mechanism 32. As a result, the seal members 34a and 34b can exert the same effect as the hanging members 26a and 26b, and can replace the hanging members 26a and 26b. In addition, on the inner and outer periphery sides of the retainer pressure top plate portion 22a, the hanging members 26a and 26b may be provided on one side, and the seal members 34a and 34b may be provided on the other side (not shown). In addition to the seal members 34a and 34b, a rotational force transmission mechanism (for example, a rotational force transmission pin) that assists in transmitting the rotational force of the head base portion 20 may be provided.

[0033] Next, as shown in FIG. 3, the polishing head 12 is provided with a workpiece pressure plate 36 below the head base portion 20 (shaft portion 20c) and on the inner peripheral side of the retainer pressure portion 22 (head lower side wall portion 22b). The workpiece pressure plate 36 is composed of two layers consisting of an upper plate 38 and a lower plate 40. The workpiece pressure plate 36 corresponds to a hard member that fixes the workpiece W during back surface reference polishing, so as an example, both the upper plate 38 and the lower plate 40 are composed of ceramics or the like, but one or both may be composed of other materials having a certain degree of flexibility. In this embodiment, as shown in FIG. 3, the upper plate 38 has an upper edge portion 38a that protrudes upward from the outer end portion thereof, and the upper plate 38 has a circular tray shape with a rim as a whole. In addition, the head base portion 20 has a lower plate portion 20d that extends to a predetermined width on the outer peripheral side on the lower surface of the shaft portion 20c. By utilizing this configuration, the work pressure plate 36 (upper edge portion 38a) is suspended on the inner periphery side from the lower plate portion 20d of the head base portion 20 via the suspension member 26c, but is not limited to this configuration. Also, on the outer periphery side, it is suspended on the head lower side wall portion 22b of the retainer pressure portion 22 via the suspension member 26d. These suspension members 26c, 26d may be configured as one unit, as shown in FIG. 4.

[0034] In this way, the work pressure plate 36 is suspended from the head base part 20 (and the retainer pressure part 22) via the suspension members 26c and 26d. The suspension members 26c and 26d according to this embodiment are both formed from diaphragms made of rubber material, and the work pressure plate 36 is configured to move up and down relative to the head base part 20 (and the retainer pressure part 22) via changes in shape of the suspension members 26c and 26d. In addition, when the head base part 20 rotates, the rotational force is transmitted via the suspension member 26c, causing the work pressure plate 36 to rotate. The configuration and material of the suspension members 26c and 26d are not limited as long as they can suspend the work pressure plate 36 so that it can move up and down as described above. That is, they are not limited to diaphragms, and may be, for example, bellows. In addition, they are not limited to rubber materials, and may be resin materials, metal materials, and the like.

[0035] Here, a third fluid chamber 42 is provided between the lower surface of the head base portion 20 (the lower surface of the lower plate portion 20d) and the upper surface of the workpiece pressure plate 36 (the upper surface of the upper plate 38) (and the hanging member 26c). A fluid can be supplied to and discharged from the third fluid chamber 42 through a third flow path 44 in which a third pressure adjustment mechanism 46 is provided. This allows the workpiece pressure plate 36 to be lowered by creating a positive pressure in the third fluid chamber 42 formed as a sealed space, or the workpiece pressure plate 36 to be raised by creating a negative pressure in the third fluid chamber 42. In this embodiment, the fluid is air, and the air pressure in the third fluid chamber 42 is adjusted, but this is not limited to this configuration, and the fluid may be water, oil, or the like. The third flow path 44, which is composed of a supply path and a discharge path, may be provided as the same pipe path or as separate pipe paths. In other words, the number of pipe paths constituting the third flow path 44 and other forms are not limited. In this embodiment, as an example, the inside of the shaft portion 20c is formed to be hollow as shown in Fig. 3. This hollow portion 45 may be conceptually understood as a part of the third fluid chamber 42 or as a part of the third flow path 44. The third pressure adjustment mechanism 46 is exemplified by a fluid compression device or an electromagnetic valve, and is driven and controlled by the control unit 72. A plurality of third pressure adjustment mechanisms 46 may be provided.

[0036] As another example, as shown in Fig. 5, the workpiece pressure plate 36 (upper edge 38a) may be provided to slidably adhere to the lower plate 20d of the head base part 20 and the head lower side wall part 22b of the retainer pressure part 22 via the seal members 34c, 34d similar to the above-mentioned seal members 34a, 34b, instead of the suspending members 26c, 26d. Also, on the inner and outer circumferential sides of the upper edge 38a, a suspending member (26c or 26d) may be provided on one side, and a seal member (34c or 34d) may be provided on the other side (not shown). Also, in addition to the seal members 34c, 34d, a rotational force transmission mechanism (for example, a rotational force transmission pin) that assists in transmitting the rotational force of the head base part 20 may be provided.

[0037] As another example of the above-described configuration in which the work pressure plate 36 moves up and down by adjusting the pressure in the third fluid chamber 42 as shown in Fig. 3, the work pressure plate 36 may be fixed to the head base portion 20 (the lower plate portion 20d in Fig. 6 is an example) as shown in Fig. 6, so that the work pressure plate 36 moves up and down and rotates together with the up and down movement and rotation of the head base portion 20 driven by the head shaft 18. In this example, as shown in Fig. 6, the third fluid chamber 42 as a pressure adjustment space does not necessarily have to be provided. Also, the head base portion 20 and the work pressure plate 36 (particularly the upper plate 38) may be integrally configured (not shown).

[0038] The polishing head 12 also includes a backing material 48 below the workpiece pressure plate 36. The peripheral portion of the backing material 48 is fixed by being sandwiched between the lower surface of the retainer pressure portion 22 (the lower surface of the widened portion 22c) and the upper surface of the retainer 24. The backing material 48 corresponds to a soft member that fixes the workpiece W during surface reference polishing, and also corresponds to a buffer member that contacts and protects the workpiece W when polishing or transporting the workpiece W. For this reason, as one example, it is configured as a sheet body made of a flexible resin material, rubber material, or the like.

[0039] The backing material 48 has an adsorption surface 48a facing the upper surface Wb of the workpiece W, and a press surface 48b, which is the surface opposite to the adsorption surface 48a and faces the workpiece pressure plate 36. When the configuration of the polishing head 12 is described with the backing material 48 at the center, a retainer 24 is provided on the outer periphery of the adsorption surface 48a, a retainer pressure part 22 that can move up and down is provided on the outer periphery of the press surface 48b, and a workpiece pressure plate 36 that can move up and down is provided in the center of the press surface 48b so as to be able to approach and separate from the press surface 48b (see FIGS. 11A, 11B, and 11C).

[0040] Also, although not visible in FIG. 3, referring to FIG. 2, a first fluid chamber 50 is provided between the lower surface of the work pressurizing plate 36 (the lower surface of the lower plate 40) and the upper surface of the backing material 48 (the press surface 48b). A fluid can be supplied to and discharged from the first fluid chamber 50 through a first flow path 52 in which a first pressure adjustment mechanism 54 is provided. In this embodiment, the fluid is air, and the air pressure in the first fluid chamber 50 is adjusted, but this is not limited to the configuration, and the fluid may be water, oil, or the like. The first flow path 52, which is composed of a supply path and a discharge path, may be provided as the same pipe path, or may be provided as separate pipe paths. In other words, the number of pipe paths constituting the first flow path 52 and other forms are not limited. The first pressure adjustment mechanism 54 is exemplified by a fluid compression device, a solenoid valve, etc., and is driven and controlled by the control unit 72. A plurality of first pressure adjustment mechanisms 54 may be provided.

[0041] As described above, the form of the first flow passage 52 is not limited, but in this embodiment, as shown in Fig. 3, the first flow passage 52 is configured to continue from the first fluid chamber 50 sandwiched between the lower surface of the lower plate 40 and the upper surface of the backing material 48 through a gap region 51 formed between the side surface (outer periphery side) of the lower plate 40 and the side surface (inner periphery side) of the retainer pressure portion 22 (widened portion 22c). The gap width of this gap region 51 can be adjusted by adjusting the radial width (diameter) of the lower plate 40 and / or the radial width of the retainer pressure portion 22 (widened portion 22c), and the region of the backing material 48 corresponding to this gap region 51 is a clearance region that does not correspond to either the retainer pressure portion 22 (retainer 24) or the work pressure plate 36 (lower plate 40). Therefore, this region is not directly pressed by the retainer pressure portion 22 and the work pressure plate 36 (lower plate 40), but is connected to the first fluid chamber 50, and is subjected to pressure adjustment by the first pressure adjustment mechanism 54 together with the first fluid chamber 50. However, the first flow path 52 may be connected to the first fluid chamber 50 without passing through the gap region 51, and the gap region 51 itself may not be provided (both are not shown). A configuration in which the gap region 51 itself is not provided may be, for example, a configuration in which the side surface (outer circumferential side) of the lower plate 40 and the side surface (inner circumferential side) of the retainer pressure portion 22 (widened portion 22c) are provided in slidable close contact with each other via seal members similar to the above-mentioned seal members 34a and 34b (not shown).

[0042] 2, when polishing the workpiece W, the control unit 72 creates a vacuum in the third fluid chamber 42, raises the workpiece pressure plate 36, forms a first fluid chamber 50 between the workpiece pressure plate 36 and the backing material 48, and then pressurizes the first fluid chamber 50. As a result, polishing pressure can be applied to the workpiece W with the back surface Wb of the workpiece W fixed to the soft backing material 48, thereby performing front surface reference polishing.

[0043] On the other hand, as shown in Fig. 3, the control unit 72 pressurizes the third fluid chamber 42 to lower the workpiece pressure plate 36, contacting the workpiece pressure plate 36 with the backing material 48, and also evacuates or opens the first fluid chamber 50 to the atmosphere to bring the workpiece pressure plate 36 into close contact with the backing material 48, and then further pressurizes the third fluid chamber 42. Alternatively, in the configuration of the embodiment shown in Fig. 6, the head shaft 18 is driven to lower the workpiece pressure plate 36, contacting the workpiece pressure plate 36 with the backing material 48, and also evacuates or opens the first fluid chamber 50 to the atmosphere to bring the workpiece pressure plate 36 into close contact with the backing material 48, and then applies a driving force to further lower the workpiece pressure plate 36 via the head shaft 18. As a result, polishing pressure is applied to the workpiece W in a state in which the back surface Wb of the workpiece W is substantially fixed to the hard workpiece pressure plate 36, and back surface reference polishing can be performed.

[0044] Here, as shown in FIG. 3, a pressing portion 23 is provided that, when the workpiece pressing plate 36 is lowered, brings the workpiece pressing plate 36 into contact with the retainer pressing portion 22 to relatively fix the workpiece pressing plate 36. The pressing portion 23 according to this embodiment is formed on an inclined surface 23a inclined with respect to the horizontal and vertical directions at a predetermined portion (the upper surface of the widened portion 22c) of the retainer pressing portion 22 and a corresponding predetermined portion (the outer end of the lower surface of the upper plate 38) of the workpiece pressing plate 36, but is not limited to this configuration. As another example, the pressing portion 23 may be formed on a spherical surface or an arc surface having a center on the rotation axis of the workpiece pressing plate 36 and the retainer pressing portion 22. This allows the entire polishing head 12 to have a more stable structure due to the centering effect. Of course, the pressing portion 23 may be formed on a horizontal surface. In addition, in this embodiment, the portion relating to the pressing portion 23 of the retainer pressure applying portion 22 is formed from a separate member from the main body of the retainer pressure applying portion 22, but the upper surface of the widening portion 22c may be processed into a predetermined shape and formed as part of the main body of the retainer pressure applying portion 22.

[0045] The pressing portion 23 functions as a stopper that restricts the movement of the workpiece pressing plate 36 and the retainer pressing portion 22 in a predetermined direction during polishing of the workpiece W, and creates a relative positional relationship between the workpiece pressing plate 36, the retainer pressing portion 22, and ultimately the components in their vicinity. As an example, in this embodiment, when the lower surface of the upper plate 38 (upper edge portion 38a) of the workpiece pressing plate 36 and the upper surface of the widened portion 22c of the retainer pressing portion 22 come into contact with each other via the pressing portion 23 formed on the inclined surface 23a during polishing of the workpiece W (during back surface reference polishing), the lower surface of the workpiece pressing plate 36 (the lower surface of the lower plate 40) comes into contact with the upper surface (press surface 48b) of the backing material 48, the gap between them disappears, and the first fluid chamber 50 appears to disappear. In this state, the vertical and horizontal movements of the workpiece pressure plate 36 and the retainer pressure part 22 are restricted, and the lower end surface IIIB of the retainer 24 is positioned above the lower end surface IIIA of the workpiece W fixed to the backing material 48, so that a predetermined gap is created between the retainer 24 and the polishing pad 16. Specifically, as shown in Fig. 3, the lower end surface IIIE of the retainer pressure part 22 and the lower end surface IIIC (the lower end surface IIID of the lower plate 40) of the workpiece pressure plate 36 are set to coincide in the horizontal direction, so that the lower end surface IIIB of the retainer 24, which is thinner than the workpiece W, is positioned above the lower end surface IIIA of the workpiece W. This makes it possible to avoid contact between the retainer 24 and the polishing pad 16 and prevent wear of the retainer 24.

[0046] On the other hand, the relative positional relationship between the retainer 24 and the workpiece W can be freely set by appropriately adjusting the shapes (particularly, thickness) of the retainer 24, the widening portion 22c, the pressing portion 23, and / or the upper plate 38 (upper edge portion 38a) of the workpiece pressing plate 36. Therefore, as another example, when the lower surface of the upper plate 38 (upper edge portion 38a) of the workpiece pressing plate 36 and the upper surface of the widening portion 22c of the retainer pressing portion 22 come into contact with each other via the pressing portion 23 during polishing of the workpiece W (when polishing the back surface as a reference), the lower end surface IIIB of the retainer 24 can be set so as to horizontally coincide with the lower end surface IIIA of the workpiece W or to be located lower than the lower end surface IIIA of the workpiece W. In this way, the pressing portion 23 accurately creates the height position of the retainer 24, particularly the relative positional relationship with the workpiece W, and contributes to accurately polishing the workpiece W into a set shape.

[0047] The pressing portion 23 also functions as a stopper for relatively positioning the work pressure plate 36 and the retainer pressure portion 22 during preliminary surface finishing processing of the work pressure plate 36 and the retainer pressure portion 22 to create the above-mentioned positional relationship. In this embodiment, as shown in Fig. 10, the work pressure plate 36 and the retainer pressure portion 22 are ground while being abutted and relatively fixed via the pressing portion 23, thereby making it possible to surface the lower end surface XE of the retainer pressure portion 22 and the lower end surface XC of the work pressure plate 36 (the lower end surface XD of the lower plate 40) so as to coincide in the horizontal direction. The details of the structure will be described later, but in a configuration in which the second fluid chamber 56 between the upper plate 38 and the lower plate 40 is connected by the first flow path 62 as shown in FIG. 10, but in a configuration in which the second fluid chamber 56 is sealed as shown in FIG. 8, the lower end surface XD of the lower plate 40 may be formed into a shape different from the horizontal plane by performing surface finishing processing by pressurizing the second fluid chamber 56 or by evacuating it or opening it to the atmosphere.

[0048] As another example, the pressing portion 23 may be configured with a positioning pin 23b erected on a horizontal surface and an insertion hole 23c into which the positioning pin 23b is inserted, at a predetermined portion (upper surface of the widened portion 22c) of the retainer pressing portion 22 and a corresponding predetermined portion (outer end of the lower surface of the upper plate 38) of the work pressing plate 36, as shown in FIG. 7 (however, FIG. 7 shows another example of the polishing head 12 shown in FIG. 2). In this example, as shown in FIG. 7, the positioning pin 23b is fixed to the retainer pressing portion 22 side, and the insertion hole 23c is provided on the work pressing plate 36 side, but conversely, the positioning pin 23b may be fixed to the work pressing plate 36 side, and the insertion hole 23c may be provided on the retainer pressing portion 22 side. In this example, as in the present embodiment, the movement of the work pressing plate 36 and the retainer pressing portion 22 in a predetermined direction (particularly, the horizontal direction) can be restricted, and a predetermined gap can be generated between the retainer 24 and the polishing pad 16. Furthermore, according to this embodiment, since the circumferential (horizontal) deviation between the retainer pressure portion 22 and the work pressure plate 36 can be effectively suppressed, especially during the surface finishing process, the lower end surface XE of the retainer pressure portion 22 and the lower end surface XC of the work pressure plate 36 (the lower end surface XD of the lower plate 40) can be matched with higher accuracy. The size, shape, number, and other configurations of the positioning pins 23b are not limited. Also, by forming the pressing portion 23 into an undulating surface or an uneven surface, etc., and configuring the work pressure plate 36 and the retainer pressure portion 22 to fit together, the circumferential (horizontal) deviation between the retainer pressure portion 22 and the work pressure plate 36 can be effectively suppressed, especially during the surface finishing process, and the same effect as that of this embodiment (positioning pins 23b) can be obtained.

[0049] As shown in FIG. 3, the second fluid chamber 56 is provided between the lower surface of the upper plate 38 and the upper surface of the lower plate 40 of the work pressure plate 36, which is configured with two layers. In this embodiment, the lower plate 40 has an upper edge portion 40a protruding upward from its outer end portion, similar to the upper plate 38, and is formed into a circular tray shape with a rim as a whole, thereby forming a space that defines the second fluid chamber 56, but this is not limited to this form. For example, the lower surface of the upper plate 38 or the upper surface of the lower plate 40 may be formed into a concave lens shape to form a space. The second fluid chamber 56 is capable of supplying and discharging fluid through a second flow path 58 in which a second pressure adjustment mechanism 60 is provided. In this embodiment, the fluid is air, and the air pressure in the second fluid chamber 56 is adjusted, but this is not limited to this configuration, and the fluid may be water, oil, or the like. The second flow path 58, which is composed of a supply path and a discharge path, may be provided as the same pipe or as separate pipes. That is, there is no limitation on the number of pipes constituting the second flow path 58 and other forms. The second pressure adjustment mechanism 60 is exemplified by a fluid compression device, a solenoid valve, etc., and is driven and controlled by the control unit 72. A plurality of second pressure adjustment mechanisms 60 may be provided.

[0050] Here, the lower plate 40 according to the present embodiment is formed porously as shown in FIG. 3, and the first fluid chamber 50 and the second fluid chamber 56 communicate with each other through a plurality of fine flow paths 62 (first flow paths 62). As a result, when the workpiece pressure plate 36 and the backing material 48 are brought into contact with each other and integrated during polishing of the workpiece W (during back surface reference polishing), the second fluid chamber 56 is evacuated, and air bubbles between the workpiece pressure plate 36 and the backing material 48 are removed from the first flow path 62 through the second fluid chamber 56, so that the adhesion between them can be further improved. The first flow path 62 may be formed by the lower plate 40 being made of a porous material, or may be provided by design in a non-porous material. The size, shape, number, and other forms of the first flow paths 62 are not limited. In addition, the first flow path 62 formed by the lower plate 40 being made of a porous material may also be connected to the first flow path 52 through the gap region 51, but the first flow path 62 designed into a non-porous material may also be configured to be connected to the first flow path 52 or not.

[0051] On the other hand, as another example, as shown in FIG. 8, instead of the first communication flow path 62, a communication flow path 64 (second communication flow path 64) that communicates the first fluid chamber 50 and the first flow path 52 may be provided in the work pressure plate 36 (lower plate 40) (however, FIG. 8 shows another example of the polishing head 12 shown in FIG. 2). In this way, by creating a vacuum in the first fluid chamber 50, air bubbles between the work pressure plate 36 and the backing material 48 can be removed from the second communication flow path 64 through the first flow path 52, thereby further improving the adhesion between them. For example, in FIG. 8, the second communication flow path 64 may be a groove 64a that passes through the lower surface of the lower plate 40, or a hole 64b that passes from the lower surface of the lower plate 40 to the inside of the lower plate 40. However, unlike the first communication flow path 62, the second communication flow path 64 does not communicate the first fluid chamber 50 and the second fluid chamber 56. The size, shape, number, and other forms of the second communication flow path 64 are not limited. Of course, both the first communication flow path 62 and the second communication flow path 64 may be provided.

[0052] As another example, as shown in Fig. 9, instead of the first communication flow path 62 and the second communication flow path 64, a communication flow path 66 (third communication flow path 66) that communicates the first fluid chamber 50 with a fifth flow path 68 in which a fifth pressure adjustment mechanism 70 is provided may be provided in the work pressure plate 36 (lower plate 40) (however, Fig. 9 shows another example of the polishing head 12 shown in Fig. 2). In this way, too, by evacuating the third communication flow path 66 via the fifth flow path 68 with the fifth pressure adjustment mechanism 70, air bubbles between the work pressure plate 36 and the backing material 48 can be removed from the third communication flow path 66 through the fifth flow path 68, thereby further improving the adhesion between them.

[0053] In this example, the fifth pressure adjustment mechanism 70 may be configured to be able to exhaust fluid from at least the third flow path 66 through the fifth flow path 68 to create a vacuum, but may also be configured to supply fluid to the third flow path 66 to pressurize it. In that case, it is of course possible to open it to the atmosphere. For example, the fifth flow path 68 consisting of a supply path and a discharge path may be provided as the same pipe line, or may be provided as separate pipe lines. In other words, the number of pipe lines constituting the fifth flow path 68 and other forms are not limited. The fifth pressure adjustment mechanism 70 is exemplified by a fluid compression device or an electromagnetic valve, and is driven and controlled by the control unit 72. A plurality of fifth pressure adjustment mechanisms 70 may be provided. In addition, the fluid is not limited, and may be water, oil, etc., for example, but when the same fluid as the fluid flowing through the first flow path 52 is selected and applied to this embodiment, it is air.

[0054] In this example, since the third flow passage 66 does not communicate with the first flow passage 52, the first pressure adjustment mechanism 54 creates a vacuum or opens the first fluid chamber 50 to the atmosphere to bring the workpiece pressure plate 36 (lower plate 40) and the backing material 48 into close contact, and then the fifth pressure adjustment mechanism 70 brings them into further close contact, so that the region of the first fluid chamber 50 corresponding to the lower plate 40 is almost eliminated, and the region is almost separated from the gap region 51. The same is true when the first flow passage 62 is configured not to communicate with the first flow passage 52, and the second pressure adjustment mechanism 60 brings the workpiece pressure plate 36 (lower plate 40) and the backing material 48 into further close contact, so that the region of the first fluid chamber 50 corresponding to the lower plate 40 is almost eliminated, and the region is almost separated from the gap region 51. This makes it possible to adjust the pressure in the gap region 51 by the first pressure adjustment mechanism 54 separately and independently of the first fluid chamber 50. Therefore, from the above state, the first pressure adjustment mechanism 54 can further pressurize, evacuate, or open the gap region 51 to the atmosphere through the first flow path 52, thereby adjusting the pressing force applied to the region corresponding to the gap region 51, mainly from the edge portion (outer periphery) of the work W to the periphery of the work W. The region corresponding to the gap region 51 can be arbitrarily set by adjusting the radial width (diameter) of the lower plate 40, the gap width of the gap region 51, and / or the radial width of the retainer pressurizing portion 22 (widened portion 22c). For example, it can include a region closer to the center of the work W, or conversely, it can be expanded from the periphery of the work W to the surrounding region. In this way, by utilizing the configuration related to the third flow path 66 or the first flow path 62 that does not communicate with the first flow path 52, the pressing force applied to the region corresponding to the gap region 51 from the edge portion of the work W to the periphery of the work W can be desiredly affected on the polished shape of the work W.

[0055] In addition, by adjusting the thickness of the upper plate 38 and / or the lower plate 40, forming them using a material with a certain degree of flexibility, or forming the upper plate 38 and / or the lower plate 40 (particularly their lower surfaces) into a special shape such as a concave lens or convex lens, it becomes possible to warp the upper plate 38 and / or the lower plate 40 upward and / or downward to change the shape by adjusting the pressure in the third fluid chamber 42 and the second fluid chamber 56. Details will be described later.

[0056] Next, a description will be given of the drive unit (not shown) of the polishing head 12. As described above, the drive unit is composed of a vertical movement drive mechanism (not shown) and a rotation drive mechanism (not shown) that are driven and controlled by the control unit 72, and moves the polishing head 12 up and down and rotates the polishing head 12 by moving the head shaft 18 up and down and rotating the head shaft 18. Both the vertical movement drive mechanism and the rotation drive mechanism of the drive unit can be constructed of known mechanisms.

[0057] Specifically, motors such as servo motors can be used as the drive sources for the vertical movement drive mechanism and the rotation drive mechanism, and spline mechanisms such as ball screw spline mechanisms and rotary ball spline mechanisms can be used as the linear motion device and the rotation device. Alternatively, a linear motor in which the drive source and the linear motion device are integrated may be used, and a linear motor actuator in which the guide mechanism for the linear motion device is also integrated may be used. In this case, a spindle may be used as the rotation device, or a linear motor actuator with a built-in rotation device may be used (neither is shown).

[0058] In addition, a current detector that detects the load on the motor, an encoder that detects the rotation speed and rotation angle, and a length measuring sensor that detects the vertical distances between the head base portion 20, retainer pressure portion 22, retainer 24, etc. and the vertical distances between these and the polishing pad 16 as the height position of the polishing head 12 are appropriately provided, and the height position of the polishing head 12 can be adjusted according to these detection values, enabling high-precision control (all not shown).

[0059] (polishing equipment) Next, as shown in FIG. 3, the polishing apparatus 10 of this embodiment is a one-sided polishing apparatus that presses a workpiece W held on the underside of the polishing head 12 of this embodiment, which is provided above a base plate 14, against a polishing pad 16 attached to the upper surface of the base plate 14, and rotates the base plate 14 and the polishing head 12 to slide relative to each other, thereby polishing the underside Wa of the workpiece W.

[0060] The surface plate 14 is formed in a disk shape in a plan view, and a polishing pad 16 is attached to the upper surface (see FIG. 3). The surface plate 14 is provided with a rotation drive mechanism (not shown) and configured to be rotatable around an axis in a horizontal plane. Also, a slurry supply unit (not shown) is provided for supplying a slurry for polishing onto the polishing pad 16. Therefore, when polishing the workpiece W, the workpiece W is supplied with slurry, and the polishing head 12 and the surface plate 14 are rotated relative to each other, so that the workpiece W and the polishing pad 16 slide relative to each other to polish the lower surface Wa of the workpiece W. The polishing pad 16 is formed of, for example, a polyurethane sheet, a nonwoven fabric sheet impregnated with polyurethane, or the like, but is not limited thereto.

[0061] (polishing method) Next, the polishing method according to this embodiment will be described using an example in which the polishing head 12 according to this embodiment (the polishing head 12 shown in FIGS. 2 and 3) is used.

[0062] First, in the front surface reference polishing, the control unit 72, as shown in FIG. 2, evacuates the third fluid chamber 42 to float the workpiece pressure plate 36 upward, forming a first fluid chamber 50 between the workpiece pressure plate 36 and the backing material 48. This first fluid chamber 50 acts as an enclosed space for pressurizing the workpiece W, and the control unit 72 then pressurizes the first fluid chamber 50. As a result, in a state in which the lower surface of the workpiece pressure plate 36 and the press surface 48b of the backing material 48 are separated from each other, and in a state in which the upper surface of the workpiece W and the suction surface 48a of the backing material 48 are in contact with each other, the workpiece W can be pressed from above to apply polishing pressure to the workpiece W. As a result, the back surface Wb of the workpiece W is fixed to the soft backing material 48, and the front surface reference polishing can be performed. Here, the control unit 72 further pressurizes the fourth fluid chamber 28 to lower the retainer 24, and the retainer 24 presses the polishing pad 16 around the workpiece W. This provides a guide ring effect to prevent the workpiece W from sliding sideways (jumping out in the radial direction), and a retainer effect to correct the deflection of the polishing pad 16 to prevent over-polishing of the edge portion, or to change the tension of the backing material 48 to have a desired effect on the polished shape of the workpiece W. In this embodiment, since the workpiece W is fixed via the backing material 48, the guide ring effect is indispensable regardless of the type of polishing method.

[0063] 2, in a configuration in which the first fluid chamber 50 and the second fluid chamber 56 communicate with each other, the control unit 72 pressurizes the second fluid chamber 56 to the same pressure as the first fluid chamber 50. On the other hand, in a configuration in which the first fluid chamber 50 and the second fluid chamber 56 do not communicate with each other as shown in FIG. 8, for example, the second fluid chamber 56 is sealed or opened to the atmosphere. In this way, deformation of the lower plate 40 is prevented.

[0064] By the above control, during front surface reference polishing according to this embodiment, the control unit 72 raises the work pressure plate 36 and lowers the retainer pressure part 22, applying forces in the vertically opposite directions to both components, thereby creating a characteristic positional relationship in which the lower end surface XIA of the work pressure plate 36 is positioned relatively higher than the lower end surface XIB of the retainer pressure part 22, as shown in Fig. 11A. The vertical movement drive mechanism for the work pressure plate 36 may of course be one that is driven by the head shaft 18 shown in Fig. 6 (vertical movement drive mechanism of the drive part) (however, Fig. 6 is an example of a state during back surface reference polishing).

[0065] With each of the fluid chambers 28, 42, 50, 56 in the above-mentioned state, the first fluid chamber 50 can be evacuated to a vacuum, thereby making it possible to pick up (lift up) the workpiece W. On the other hand, to unload (peel off) the workpiece W, air can be introduced again into the first fluid chamber 50. That is, according to this embodiment, the backing material 48 can be used as a suction disk to fix (hold) and pick up the workpiece W, and is not formed porous as in the conventional configuration. Therefore, when picking up and unloading, it is possible to prevent suction marks on the workpiece W and the intrusion of foreign matter into the polishing head 12.

[0066] Next, during the back surface reference polishing, as shown in FIG. 3, the control unit 72 pressurizes the third fluid chamber 42 to lower the workpiece pressure plate 36 and bring the workpiece pressure plate 36 into contact with the backing material 48. In this state, the first fluid chamber 50 appears to disappear, but the control unit 72 evacuates the first fluid chamber 50 or opens it to the atmosphere to bring the workpiece pressure plate 36 and the backing material 48 into close contact, and then applies a downward force to the workpiece pressure plate 36. Specifically, in the present embodiment shown in FIG. 3, the third fluid chamber 42 is further pressurized to apply a downward force to the workpiece pressure plate 36. Also, in the configuration of the embodiment shown in FIG. 6, the head shaft 18 is driven to lower the workpiece pressure plate 36, and as described above, the workpiece pressure plate 36 and the backing material 48 are brought into contact with each other, and then the first fluid chamber 50 is evacuated or opened to the atmosphere to bring the workpiece pressure plate 36 and the backing material 48 into close contact. Next, a driving force is applied via the head shaft 18 to further lower the workpiece pressure plate 36, thereby applying a downward force to the workpiece pressure plate 36. As a result, in a state in which the lower surface of the workpiece pressure plate 36 is in contact with the press surface 48b of the backing material 48 and in a state in which the upper surface of the workpiece W is in contact with the suction surface 48a of the backing material 48, the workpiece W can be pressed from above to apply a polishing pressure to the workpiece W. As a result, the back surface Wb of the workpiece W is substantially fixed to the hard workpiece pressure plate 36, and back surface reference polishing can be performed.

[0067] At this time, according to the present embodiment, as described above, when the workpiece pressure plate 36 is lowered, the workpiece pressure plate 36 comes into contact with the retainer pressure portion 22, and the workpiece pressure plate 36 comes into contact with the backing material 48. In this state, when performing back surface reference polishing, as shown in FIG. 3, the lower end surface IIIB of the retainer 24 is located above the lower end surface IIIA of the workpiece W fixed to the backing material 48, so that a predetermined gap is generated between the retainer 24 and the polishing pad 16. In the back surface reference polishing, polishing is performed according to the shape of the hard member created on the upper surface Wb, which is the back surface Wb of the workpiece W, so that the requirement for the retainer effect to prevent over-polishing of the edge portion of the workpiece W due to the deflection of the polishing pad 16 is relatively low, while wear of the retainer 24 due to the contact of the retainer 24 with the polishing pad 16 is likely to be an issue. In contrast, according to the present embodiment, contact between the retainer 24 and the polishing pad 16 can be avoided, and wear of the retainer 24 can be prevented. Also, since the gap between the retainer 24 and the polishing pad 16 can be set to a minute gap that can prevent wear of the retainer 24, a guide ring effect can be obtained as a matter of course. On the other hand, by placing importance on the influence of the retainer effect on the polished shape of the workpiece W, it is also possible to perform polishing while the retainer 24 is in contact (pressed) with the polishing pad 16 without creating a gap between the retainer 24 and the polishing pad 16, thereby polishing to a desired polished shape.

[0068] In this embodiment, the control unit 72 maintains the contact state between the workpiece pressure plate 36 and the retainer pressure portion 22 by adjusting the pressure in the fourth fluid chamber 28 to an extent that supports the retainer pressure portion 22 (its own weight). Specifically, the workpiece pressure plate 36 abuts against the retainer pressure portion 22 from above, applying a predetermined pressure. Therefore, the control unit 72 normally reduces the pressure in the fourth fluid chamber 28 appropriately so as not to impede the pressing force of the workpiece pressure plate 36 and to maintain the contact state between the workpiece pressure plate 36 and the retainer pressure portion 22. This allows a predetermined gap to be generated between the retainer 24 and the polishing pad 16, as described above.

[0069] In addition, in a configuration in which the lower plate 40 has the first communication flow path 62 and the first fluid chamber 50 and the second fluid chamber 56 are in communication with each other, the control unit 72 evacuates the second fluid chamber 56. This allows air bubbles between the workpiece pressure plate 36 and the backing material 48 to be removed from the first communication flow path 62 through the second fluid chamber 56, thereby further improving the adhesion between them. At this time, in a configuration in which the first communication flow path 62 also communicates with the first flow path 52, the first fluid chamber 50 is also evacuated. In addition, in a configuration in which the lower plate 40 has the second communication flow path 64 and the first fluid chamber 50 and the second fluid chamber 56 are not in communication with each other, the control unit 72 evacuates the first fluid chamber 50. This allows air bubbles between the workpiece pressure plate 36 and the backing material 48 to be removed from the second communication flow path 64 through the first flow path 52, thereby further improving the adhesion between them. At this time, the second fluid chamber 56 may be either a vacuum or open to the atmosphere. In addition, in a configuration in which the lower plate 40 has a third flow passage 66 and the first fluid chamber 50 communicates with a fifth flow passage 68 in which a fifth pressure adjustment mechanism 70 is provided via the third flow passage 66, the control unit 72 evacuates the third flow passage 66 by the fifth pressure adjustment mechanism 70. This allows air bubbles between the workpiece pressure plate 36 and the backing material 48 to be removed from the third flow passage 66 through the fifth flow passage 68, thereby further improving the adhesion between them. At this time, the inside of the second fluid chamber 56 may be either a vacuum or open to the atmosphere. In this way, air pockets between the workpiece pressure plate 36 and the backing material 48 are removed, so that the two can be sufficiently adhered to each other without unevenness. As a result, the back surface Wb of the workpiece W can be more precisely aligned to the shape of the hard workpiece pressure plate 36 (lower plate 40) to perform accurate back surface reference polishing.

[0070] In addition, in a configuration having the first flow path 62 or the third flow path 66 which is not connected to the first flow path 52, while maintaining a state in which the work pressure plate 36 and the backing material 48 are sufficiently in close contact with each other, the first pressure adjustment mechanism 54 pressurizes, evacuates, or opens the gap region 51 to the atmosphere through the first flow path 52, thereby adjusting the pressing force applied to the region from the edge of the work W to the periphery of the work W, which corresponds to the gap region 51, and the like, thereby achieving the desired effect on the polished shape of the work W.

[0071] By the above control, during the back surface reference polishing according to this embodiment, the control unit 72 applies forces in the directions that lower the workpiece pressure plate 36 and raise the retainer pressure part 22, and applies forces in the vertically opposite directions to both components, thereby creating a characteristic positional relationship in which the lower end surface XIA of the workpiece pressure plate 36 and the lower end surface XIB of the retainer pressure part 22 are horizontally aligned as shown in Fig. 11B, or the lower end surface XIA of the workpiece pressure plate 36 is positioned relatively lower than the lower end surface XIB of the retainer pressure part 22 as shown in Fig. 11C. The vertical movement of the workpiece pressure plate 36 may of course be driven by the head shaft 18 shown in Fig. 6 (the vertical movement drive mechanism of the drive part).

[0072] As mentioned above, by adjusting the thickness of the upper plate 38 and / or the lower plate 40, forming them using a material having a certain degree of flexibility, or forming the upper plate 38 and / or the lower plate 40 (particularly their lower surfaces) into a special shape such as a concave lens or convex lens shape, it becomes possible to change the shape of the upper plate 38 and / or the lower plate 40 by bending them upward and / or downward by adjusting the pressure in the third fluid chamber 42 and the second fluid chamber 56.

[0073] As a result, during back surface reference polishing, for example, the second fluid chamber 56 can be evacuated to form the lower plate 40 into a desired shape, and polishing can be performed by having it follow the back surface Wb of the workpiece W. In addition, for example, the third fluid chamber 42 can be evacuated to form the upper plate 38 into a desired shape, and the second fluid chamber can be evacuated to adsorb the lower plate 40 to the upper plate 38 whose shape has been changed, so that the shape of the lower plate 40 follows the shape of the upper plate 38, and thus polishing can be performed by having it follow the back surface Wb of the workpiece W. When the third fluid chamber 42 is used to change the shape of the workpiece pressure plate 36 (upper plate 38), the up and down movement of the workpiece pressure plate 36 may be configured to be performed by driving the head shaft 18 shown in FIG. 6 (up and down movement drive mechanism of the drive unit).

[0074] In this way, by combining a change in the shape of the central part of the workpiece W by changing the configuration such as the shape of the upper plate 38 and / or the lower plate 40 with a change in the shape of the outer periphery of the workpiece W by utilizing the first flow path 62 or the third flow path 66 which are not connected to the aforementioned first flow path 52, and the gap area 51, it is possible to change the polishing shape of the workpiece W in an extremely diverse manner, thereby making it possible to accurately polish the workpiece W to the desired shape.

[0075] According to the present invention, both front surface reference polishing and back surface reference polishing can be performed with one polishing head. This can reduce downtime, reduce equipment costs, and simplify the size of the equipment. In addition, since the workpiece pressure plate can be separated from the backing material to form a gap, the backing material can be used as a suction cup to fix and pick up the workpiece. This eliminates the need to provide suction holes in the backing material, and as a result, it is possible to prevent suction marks on the workpiece and the intrusion of foreign matter into the polishing head. [Explanation of symbols]

[0076] 10 Polishing equipment 12 Polishing head 14 Fixed Plate 16 Polishing Pad 18 Head axis 20 Head base part 22 Retainer pressure section 23 Pressing section 23a Slope 24 Retainer 28 4th fluid chamber 30 4th Stream 32 Fourth pressure adjustment mechanism 36 Work pressure plate 38 Upper Plate 40 Lower plate 42 Third fluid chamber 44 3rd Stream 46 Third pressure adjustment mechanism 48 Backing material 48a Adsorption surface 48b Press surface 50 1st fluid chamber 51 Gap Area 52 First Channel 54 First pressure adjustment mechanism 56 2nd fluid chamber 58 Second Stream 60 Second pressure adjustment mechanism 62 1st flow path 64 2nd flow path 66 Third flow path 68 5th Stream 70 5th pressure adjustment mechanism 72 Control section Double work Wa polished surface, top surface, bottom surface Wb non-polished surface, back surface, top surface

Claims

1. A polishing head is fixed to a head shaft that can move up and down and rotate, and is provided so as to be movable up and down and rotatable, and holds a workpiece and presses it against a polishing pad while rotating the workpiece, A backing material having an adsorption surface facing the upper surface of the workpiece and a press surface opposite to the adsorption surface; A work pressure plate is provided at the center of the press surface so as to be movable toward and away from the press surface and is movable up and down; A first fluid chamber provided between the workpiece pressure plate and the backing material; a first pressure adjustment mechanism that adjusts the pressure in the first fluid chamber, The control unit: a surface reference polishing step in which the workpiece is pressed from above while the lower surface of the workpiece pressure plate and the pressing surface of the backing material are separated from each other and the upper surface of the workpiece and the suction surface of the backing material are brought into contact with each other by controlling the pressure in the first fluid chamber; a back surface reference polishing process in which the workpiece is pressed from above while the lower surface of the workpiece pressure plate is in contact with the pressing surface of the backing material and the upper surface of the workpiece is in contact with the suction surface of the backing material by controlling the inside of the first fluid chamber to be vacuum or open to the atmosphere and applying a downward force to the workpiece pressure plate; The polishing head is characterized by:

2. a retainer provided on an outer periphery of the attraction surface; A retainer pressure unit is provided on the outer periphery of the press surface and is movable up and down. The control unit applies forces in the vertically opposite directions to the retainer pressure unit and the workpiece pressure plate, In the surface reference polishing, polishing is performed in a state in which the lower end surface of the workpiece pressure plate is positioned relatively higher than the lower end surface of the retainer pressure portion, In the back surface reference polishing, polishing is performed in a state in which the lower end surface of the workpiece pressure plate and the lower end surface of the retainer pressure part are horizontally aligned, or in a state in which the lower end surface of the workpiece pressure plate is positioned relatively lower than the lower end surface of the retainer pressure part.

2. The polishing head according to claim 1,

3. A pressing portion that abuts the work pressure plate and the retainer pressure portion to fix them relatively, The pressing portion functions as a stopper that restricts the movement of the work pressing plate and the retainer pressing portion in a predetermined direction to create a relative positional relationship during polishing of the work.

3. The polishing head according to claim 2,

4. During the back surface reference polishing, when the workpiece is pressed against the polishing pad in a state in which the workpiece pressure plate and the retainer pressure portion are in contact with each other via the pressing portion, a gap is formed between the retainer and the polishing pad.

4. The polishing head according to claim 3,

5. The work pressure plate is composed of two layers consisting of an upper plate and a lower plate, a second fluid chamber between the upper plate and the lower plate; A second pressure adjustment mechanism that adjusts the pressure in the second fluid chamber, The lower plate has a flow passage that communicates between the first fluid chamber and the second fluid chamber.

3. The polishing head according to claim 1 or 2, wherein:

6. The flow passage is formed by making the lower plate from a porous material.

6. The polishing head according to claim 5,

7. The workpiece pressing plate has a communication passage that communicates the first fluid chamber with a first passage in which the first pressure adjustment mechanism is provided.

3. The polishing head according to claim 1 or 2, wherein:

8. The flow passage is a groove formed on the lower surface of the work pressure plate.

8. The polishing head according to claim 7,

9. the workpiece pressure plate has a communication passage that communicates the first fluid chamber with a fifth passage in which a fifth pressure adjustment mechanism is provided, The fifth pressure adjustment mechanism is configured to be able to evacuate at least the communication passage through the fifth passage.

3. The polishing head according to claim 1 or 2, wherein:

10. A head base portion fixed to the head shaft is further provided, The work pressure plate is fixed to the head base portion and moves up and down by driving the head shaft, The control unit performs control to apply a downward force to the workpiece pressure plate by applying a driving force to lower the workpiece pressure plate via the head shaft during the back surface reference polishing. or the work pressure plate is suspended from or slidably attached to the head base portion, and the pressure in a third fluid chamber provided between the head base portion and the work pressure plate is adjusted by a third pressure adjustment mechanism, whereby the work pressure plate moves up and down; The control unit performs control to apply a downward force to the workpiece pressure plate by pressurizing the third fluid chamber during the back surface reference polishing.

3. The polishing head according to claim 1 or 2, wherein:

11. A polishing apparatus comprising the polishing head according to claim 1 or 2.

12. A backing material having an adsorption surface facing the upper surface of the workpiece and a press surface opposite to the adsorption surface; a workpiece pressure plate provided at a center of the press surface so as to be movable toward and away from the press surface and movable up and down; and a polishing head including a polishing pad and a workpiece held by the polishing head, the polishing pad being pressed against the workpiece, the polishing pad comprising: a surface reference polishing step in which the workpiece is pressed from above in a state in which the lower surface of the workpiece pressure plate is separated from the press surface of the backing material by raising the workpiece pressure plate to form an enclosed space between the workpiece pressure plate and the backing material and pressurizing the enclosed space, and in which the upper surface of the workpiece is brought into contact with the suction surface of the backing material; a back surface reference polishing in which the workpiece is pressed from above in a state in which the lower surface of the workpiece pressure plate is in contact with the press surface of the backing material and in a state in which the upper surface of the workpiece is in contact with the suction surface of the backing material by applying a downward force to the workpiece pressure plate while making the sealed space a vacuum or opening it to the atmosphere; A polishing method characterized by the above.

13. a retainer provided on an outer periphery of the attraction surface; By using the polishing head further including a retainer pressure unit provided on the outer periphery of the press surface and movable up and down, In the surface reference polishing, the retainer pressurizing part is lowered to press the polishing pad around the workpiece with the retainer, In the back surface reference polishing, a gap is formed between the lower end surface of the retainer and the polishing pad. The polishing method according to claim 12, characterized in that

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