Polishing head, polishing apparatus, and polishing method

Abstract

The invention provides a polishing head, a polishing apparatus, and a polishing method. According to the present invention, the front surface reference grinding and the back surface reference grinding can be performed with one grinding head, downtime reduction, equipment cost reduction and equipment miniaturization and simplification can be realized, and adsorption marks and foreign matters on a workpiece can be prevented from being mixed into the grinding head. The polishing head includes a backing material having a suction surface facing the upper surface of the workpiece and a press surface on the opposite side, a workpiece pressing plate positioned in the center of the press surface, and a first fluid chamber between the workpiece pressing plate and the backing material, and the control unit switches between front-surface reference polishing and back-surface reference polishing, in the front-surface reference polishing, in the back-surface reference polishing, in the back-surface reference polishing, in the back-surface reference polishing. In the back surface reference polishing, a downward force is applied to the workpiece pressing plate while the interior of the first fluid chamber is vacuumized or opened to the atmosphere, and the workpiece pressing plate is pressed while the workpiece pressing plate and the backing material are separated from each other, and in the back surface reference polishing, a downward force is applied to the workpiece pressing plate while the interior of the first fluid chamber is vacuumized or opened to the atmosphere. As a result, the workpiece is polished while the workpiece pressing plate is brought into contact with the backing material.

Description

Technical Field

[0001] The invention relates to a grinding head, a grinding device and a grinding method. Background Art

[0002] In a grinding device, there is a known grinding head: the grinding head is arranged to be able to move up and down and rotate, and while holding a workpiece to rotate it, the workpiece is pressed against a grinding pad to grind it. In addition, there is a known grinding device: the workpiece is held on the lower surface of the grinding head arranged above a platform, and while the workpiece is pressed against a grinding pad attached to the upper surface of the platform, the platform and the grinding head are rotated and relatively slid to grind the workpiece. The grinding device is a single-sided grinding device that grinds a single side of a workpiece.

[0003] As described in Patent Document 1 (Japanese Patent No. 5629594), there are generally two polishing methods using a single-side polishing device (see Patent Document 1: Figure 5 ). One method is back reference grinding, which is a method of grinding by fixing the back side of the workpiece (the upper surface as the non-grinding surface) to a relatively hard and flat surface. In this case, the front side of the workpiece (the lower surface as the grinding surface) is ground according to the shape of the back side, that is, the shape of the above-mentioned flat surface of the grinding head. On the other hand, another method is front reference grinding, which is a method of grinding by fixing the back side of the workpiece to a relatively soft elastic surface. In this case, the front side of the workpiece is ground according to the shape of the front side.

[0004] Patent Document 1: Japanese Patent No. 5629594

[0005] The grinding of the workpiece is carried out by using front reference grinding and back reference grinding according to the purpose.

[0006] However, the existing grinding heads for performing front reference grinding and back reference grinding have different basic structures, so it is necessary to replace the grinding head according to each grinding method, or to install multiple grinding devices. Therefore, downtime caused by replacing the grinding head, increase in equipment cost, and enlargement and complexity of the equipment caused by using multiple grinding heads or grinding devices have become problems.

[0007] Furthermore, in the existing grinding head (grinding device), when the back side of the workpiece is fixed to a relatively soft elastic surface, the soft component is formed into a porous adsorption hole, and air is sucked from the hole to adsorb and fix the workpiece. Therefore, it is possible that adsorption marks are generated on the workpiece due to the fixation or picking up of the workpiece. Furthermore, when picking up, water, slurry, and other foreign matter may also be sucked into the grinding head from the adsorption hole together with air, causing the grinding head to have a malfunction. Summary of the invention

[0008] The present invention has been completed in view of the above situation, and its purpose is to provide the following grinding head, grinding device and grinding method: one grinding head can be used to perform both front reference grinding and back reference grinding, which can achieve reduction in downtime, reduction in equipment costs, and miniaturization and simplification of equipment, and can also prevent adsorption marks and foreign matter on the workpiece from mixing into the interior of the grinding head.

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

[0010] The grinding head of the present invention is fixed to a head shaft that can move up and down and rotate and is arranged to be able to move up and down and rotate. The grinding head holds the workpiece to rotate the workpiece while pressing the workpiece against the grinding pad to grind. It is characterized in that the grinding head comprises: a backing material, which has an adsorption surface opposite to the upper surface of the workpiece and a stamping surface on the opposite side of the adsorption surface; a workpiece pressure plate, which is arranged at the central part of the stamping surface in a manner that can contact and separate from the stamping surface and can move up and down; a first fluid chamber, which is arranged between the workpiece pressure plate and the backing material; and a first pressure adjustment mechanism, which adjusts the pressure inside the first fluid chamber, and a control unit switches between front reference grinding and back reference grinding. Quasi-grinding control, in the front reference grinding, the interior of the first fluid chamber is controlled to be pressurized, thereby pressing the workpiece from above with the lower surface of the workpiece pressure plate separated from the stamping surface of the backing material and the upper surface of the workpiece in contact with the adsorption surface of the backing material, and in the back reference grinding, the interior of the first fluid chamber is controlled to be vacuous or open to the atmosphere and a downward force is applied to the workpiece pressure plate, thereby pressing the workpiece from above with the lower surface of the workpiece pressure plate in contact with the stamping surface of the backing material and the upper surface of the workpiece in contact with the adsorption surface of the backing material.

[0011] Thus, one grinding head can be used for both front reference grinding and back reference grinding. In addition, the workpiece pressing plate can be separated from the backing material to form a gap, so the backing material can be used as an adsorption plate to fix and pick up the workpiece. Therefore, there is no need to provide adsorption holes in the backing material, and as a result, adsorption marks and foreign matter on the workpiece can be prevented from being mixed into the inside of the grinding head.

[0012] In addition, the grinding head of the present invention also includes: a retainer, which is arranged on the outer periphery of the adsorption surface; and a retainer pressure portion, which is arranged on the outer periphery of the stamping surface and can move up and down. The grinding head is configured such that, by the control portion applying forces in opposite directions to the retainer pressure portion and the workpiece pressure plate relative to each other, in the front reference grinding, grinding is performed in a state where the lower end face of the workpiece pressure plate is located relatively above the lower end face of the retainer pressure portion, and in the back reference grinding, grinding is performed in a state where the lower end face of the workpiece pressure plate is horizontally consistent with the lower end face of the retainer pressure portion, or the lower end face of the workpiece pressure plate is located relatively below the lower end face of the retainer pressure portion.

[0013] Furthermore, preferably, the grinding head of the present invention has an abutment portion that causes the workpiece pressure plate and the retainer pressure portion to abut and relatively fix each other, and the abutment portion functions as a stopper that limits the movement of the workpiece pressure plate and the retainer pressure portion in a specified direction to form a relative positional relationship when grinding the workpiece.

[0014] Furthermore, as an example of the positional relationship, when the workpiece is pressed against the polishing pad in a state where the workpiece pressing plate and the retainer pressing portion are in contact with each other via the contact portion during the back reference polishing, a gap is formed between the retainer and the polishing pad. Thus, during the back reference polishing, the retainer can be prevented from contacting with the polishing pad, thereby preventing the retainer from being worn.

[0015] Furthermore, preferably, the workpiece pressure plate is composed of two layers including an upper plate and a lower plate, and the polishing head further comprises: a second fluid chamber located between the upper plate and the lower plate; and a second pressure adjustment mechanism that adjusts the pressure inside the second fluid chamber, and the lower plate has a flow path that connects the first fluid chamber with the second fluid chamber. Thus, during back reference polishing, when the workpiece pressure plate and the backing material are brought into contact and integrated, by making the interior of the second fluid chamber a vacuum, 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 their closeness. As an example, the flow path can be formed by the lower plate being composed of a porous material.

[0016] Alternatively, the workpiece pressurizing plate preferably has a flow passage that connects the first fluid chamber to the first flow passage provided with the first pressure adjusting mechanism. Thus, during back reference grinding, when the workpiece pressurizing plate and the backing material are brought into contact and integrated, bubbles between the workpiece pressurizing plate and the backing material can be removed from the flow passage via the first flow passage by making the interior of the first fluid chamber evacuated, thereby further improving their close adhesion. As an example, the flow passage can be formed as a groove on the lower surface of the workpiece pressurizing plate.

[0017] Alternatively, the workpiece pressurizing plate preferably has a flow passage that connects the first fluid chamber with a fifth flow passage provided with a fifth pressure regulating mechanism, and the fifth pressure regulating mechanism is configured to be able to make at least the flow passage a vacuum through the fifth flow passage. Thus, during back reference grinding, when the workpiece pressurizing plate and the backing material are brought into contact and integrated, the flow passage is made a vacuum through the fifth flow passage by using the fifth pressure regulating mechanism, so that bubbles between the workpiece pressurizing plate and the backing material can be removed from the flow passage through the fifth flow passage, thereby further improving their close adhesion.

[0018] Furthermore, the grinding head of the present invention may be configured as follows: the grinding head further includes a head base portion fixed to the head shaft, the workpiece pressure plate is configured to be fixed to the head base portion and move up and down by the drive of the head shaft, and the control unit performs the following control: during the back reference grinding, a downward force is applied to the workpiece pressure plate by applying a driving force to lower the workpiece pressure plate via the head shaft. Alternatively, the grinding head of the present invention may be configured as follows: the grinding head further includes a head base portion fixed to the head shaft, the workpiece pressure plate is configured to be suspended from the head base portion or slidably fit with the head base portion, the workpiece pressure plate moves up and down by adjusting the pressure inside the third fluid chamber provided between the head base portion and the workpiece pressure plate by the third pressure adjustment mechanism, and the control unit performs the following control: during the back reference grinding, a downward force is applied to the workpiece pressure plate by pressurizing the inside of the third fluid chamber.

[0019] Furthermore, the polishing device of the present invention is characterized in that the polishing device includes the polishing head of the present invention.

[0020] Furthermore, the grinding method of the present invention presses a workpiece held by a grinding head against a grinding pad for grinding, and the grinding head comprises: a backing material, which has an adsorption surface opposite to the upper surface of the workpiece and a stamping surface on the opposite side of the adsorption surface; and a workpiece pressure plate, which is arranged at the central part of the stamping surface in a manner capable of contacting and separating with the stamping surface and can move up and down, and is characterized in that the grinding method switches between front reference grinding and back reference grinding, and in the front reference grinding, the workpiece pressure plate is raised to form a closed space between the workpiece pressure plate and the backing material, and the workpiece pressure plate is pressed against the backing material. The enclosed space is pressurized, thereby pressing the workpiece from above with the lower surface of the workpiece pressure plate separated from the stamping surface of the backing material and the upper surface of the workpiece in contact with the adsorption surface of the backing material. During the back-side reference grinding, the enclosed space is made into a vacuum or opened to the atmosphere, and a downward force is applied to the workpiece pressure plate, thereby pressing the workpiece from above with the lower surface of the workpiece pressure plate in contact with the stamping surface of the backing material and the upper surface of the workpiece in contact with the adsorption surface of the backing material.

[0021] Furthermore, the grinding head may also include: a retainer, which is arranged on the periphery of the adsorption surface; and a retainer pressing portion, which is arranged on the periphery of the stamping surface and can move up and down. The grinding method is performed by using the grinding head, and in the front reference grinding, the retainer pressing portion is lowered and the retainer is used to press the grinding pad around the workpiece, and in the back reference grinding, a gap is formed between the lower end surface of the retainer and the grinding pad.

[0022] According to the present invention, one grinding head can be used for both front reference grinding and back reference grinding. Therefore, it is possible to reduce downtime, reduce equipment costs, and miniaturize and simplify equipment. In addition, the workpiece pressure plate can be separated from the backing material to form a gap, so the backing material can be used as an adsorption disk to fix and pick up the workpiece. Therefore, it is not necessary to provide adsorption holes in the backing material, and as a result, it is possible to prevent adsorption marks and foreign matter on the workpiece from mixing into the interior of the grinding head. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram (front view) showing an example of a polishing head according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram (front cross-sectional view) showing an example of a polishing head according to an embodiment of the present invention, and shows an example of a state during front reference polishing.

[0025] Figure 3It is a schematic diagram (front cross-sectional view) showing an example of a polishing head according to an embodiment of the present invention, and shows an example of a state during back surface reference polishing.

[0026] Figure 4 It is shown Figure 3 A schematic diagram (front cross-sectional view) of another example of the polishing head shown.

[0027] Figure 5 It is shown Figure 3 A schematic diagram (front cross-sectional view) of another example of the polishing head shown.

[0028] Figure 6 It is shown Figure 3 A schematic diagram (front cross-sectional view) of another example of the polishing head shown.

[0029] Figure 7 It is shown Figure 2 A schematic diagram (front cross-sectional view) of another example of the polishing head shown.

[0030] Figure 8 It is shown Figure 2 A schematic diagram (front cross-sectional view) of another example of the polishing head shown.

[0031] Fig. 9 It is shown Figure 2 A schematic diagram (front cross-sectional view) of another example of the polishing head shown.

[0032] Fig.10 Yes Figure 3 An explanatory diagram for explaining an example of face straightening processing by the polishing head shown.

[0033] FIG. 11A to FIG. 11C This is an explanatory diagram for explaining an example of the polishing method according to the present embodiment. Fig.11A This is an explanatory diagram for explaining front reference grinding. Fig. 11B and Fig. 11C This is an explanatory diagram for explaining back side reference grinding. DETAILED DESCRIPTION

[0034] (Grinding head)

[0035] Hereinafter, a mode for carrying out the present invention will be described in detail with reference to the drawings. Figure 1 : is a schematic diagram (front view) showing an example of the polishing head 12 of this embodiment. Figure 2 and Figure 3 : is a schematic diagram (front cross-sectional view) showing an example of the polishing head 12 of this embodiment. Figure 2 An example of the state during front reference grinding is shown. Figure 3The example of the state when the back side is ground is shown, but the structure is the same. Therefore, in the description of the structure, reference is made to Figure 1 and Figure 3 , and also refer to Figure 2 .and, Figures 4 to 9 1 is a schematic diagram (front cross-sectional view) showing another example of the polishing head 12 of this embodiment, and reference is also made to these drawings as appropriate. Figures 4 to 6 Show Figure 3 Other examples of the grinding head 12 shown, Figures 7 to 9 Show Figure 2 Other examples of the grinding head 12 shown. In addition, the grinding head 12 is a device of the grinding device 10. Figures 1 to 9 This is also a schematic diagram of the polishing device 10 according to this embodiment, which also shows peripheral components such as the platen 14 and the polishing pad 16 .

[0036] like Figure 1 and Figure 3 As shown, the grinding head 12 of this embodiment is a device that has the function of moving up and down and rotating while keeping the grinding surface Wa of the workpiece W facing the bottom in a horizontal state. In the grinding device 10, the workpiece W is rotated while pressing the workpiece W from above to the grinding pad 16 attached to the upper surface of the platform 14 rotating in the horizontal plane, thereby grinding the grinding surface Wa of the workpiece W. In addition, the workpiece W is, for example, a flat plate (especially a circular plate) grinding object made of semiconductor material or glass material. The grinding surface Wa of the workpiece W is the front surface Wa, which is equivalent to the lower surface Wa, and the non-grinding surface Wb of the workpiece W is the back surface Wb, which is equivalent to the upper surface Wb.

[0037] The grinding head 12 has a head base 20 at the upper part. The head base 20 has: a disc-shaped head base top plate 20a; a cylindrical head upper side wall 20b, which protrudes downward from the outer end of the head base top plate 20a; and a shaft 20c, which protrudes downward from the central part of the lower surface of the head base top plate 20a. Thus, the head base 20 is protected by covering the upper part of the grinding head 12 with a cover. In addition, the central part of the upper surface of the head base 20 (the upper surface of the head base top plate 20a) is fixed to the head shaft 18 that can move up and down and rotate. The head shaft 18 moves up and down by means of a vertical movement driving mechanism (not shown) of the driving part. Therefore, the head base 20 moves up and down together with the head shaft 18. In addition, the head shaft 18 rotates around the axis line by means of a rotation driving mechanism (not shown) of the driving part. Therefore, the head base 20 rotates around the head shaft 18. Thus, the polishing head 12 is provided so as to be able to move up and down and rotate by the drive of the head shaft 18. The up and down movement drive mechanism and the rotation drive mechanism of the driving unit can be constituted by known mechanisms. Specific examples will be described later.

[0038] Then, if Figure 1 and Figure 3 As shown, the grinding head 12 has a retainer pressurizing portion 22 at the lower part (below the head base portion 20). The retainer pressurizing portion 22 has: a retainer pressurizing top plate portion 22a, which is located inside the grinding head 12 and below the head base top plate portion 20a; a head lower side wall portion 22b, which protrudes downward from the outer end of the retainer pressurizing top plate portion 22a; and a widening portion 22c, which expands a predetermined width toward the inner peripheral side on the lower surface of the head lower side wall portion 22b. Thus, the retainer pressurizing portion 22 is protected in a manner that the head lower side wall portion 22b covers the lower periphery of the grinding head 12. In addition, on the lower surface of the retainer pressurizing portion 22 (the lower surface of the widening portion 22c), a retainer 24 for pressing the grinding pad 16 around the workpiece W is provided with a backing material 48 described later.

[0039] And, if Figure 3 As shown in FIG. 1 , the retainer pressurizing portion 22 (retainer pressurizing top plate portion 22a) is suspended on the outer periphery of the shaft portion 20c of the head base portion 20 via the suspension member 26a on the inner periphery side. Also, it is suspended on the inner periphery of the head upper side wall portion 20b of the head base portion 20 via the suspension member 26b on the outer periphery side. Figure 4 As shown, the suspension components 26a and 26b are formed as one body.

[0040] In this way, the retainer pressurizing portion 22 is suspended from the head base portion 20 via the suspension components 26a and 26b. The suspension components 26a and 26b of the present embodiment are both formed of a diaphragm of a rubber material, and the retainer pressurizing portion 22 is configured to move up and down relative to the head base portion 20 via the shape change of the suspension components 26a and 26b. Furthermore, when the head base portion 20 rotates, its rotational force is transmitted to the retainer pressurizing portion 22 via the suspension components 26a and 26b to rotate it. The structure and material of the suspension components 26a and 26b are not limited as long as they can suspend the retainer pressurizing portion 22 so that it can move up and down as described above. That is, it is not limited to a diaphragm, and it may be, for example, a bellows, etc. Furthermore, it is not limited to a rubber material, and it may be a resin material, a metal material, etc.

[0041] 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 parts 26a, 26b). The fourth fluid chamber 28 can supply and discharge fluid via the fourth flow path 30 provided with the fourth pressure adjustment mechanism 32. Thus, the retainer pressurizing portion 22 (retainer 24) can be lowered by making the fourth fluid chamber 28 formed as a closed space positively pressurized, and on the other hand, the retainer pressurizing portion 22 (retainer 24) can be raised by making the fourth fluid chamber 28 negatively pressurized. In the present embodiment, the fluid is set to air and the air pressure in the fourth fluid chamber 28 is adjusted, but the present invention is not limited to this structure. For example, the fluid may be water, oil, etc. The supply path and the discharge path of the fourth flow path 30 composed of the supply path and the discharge path may be provided as the same pipeline or different pipelines. That is, the number of pipes constituting the fourth flow path 30 and other forms are not limited. The fourth pressure regulating mechanism 32 can be exemplified by a fluid compression device or an electromagnetic valve, etc., which is driven and controlled by the control unit 72. The control unit 72 provided at a predetermined position in the polishing device 10 is composed of a CPU and a memory, and performs a predetermined operation according to a preset action program and / or a setting signal input from an operation unit (not shown). A plurality of the fourth pressure regulating mechanisms 32 may be provided.

[0042] In this way, the retainer pressurizing portion 22 can be moved up and down by adjusting the pressure in the fourth fluid chamber 28, thereby adjusting the up and down position of the retainer 24. Therefore, when grinding the workpiece W (front reference grinding), the retainer 24 is lowered, and the retainer 24 presses the grinding pad 16 around the workpiece W, which can provide a so-called retainer effect that prevents the edge of the workpiece W from being over-grinded and affects the grinding shape of the workpiece W, and the pressing force can be adjusted to a desired pressing force. On the other hand, when grinding the workpiece W (back reference grinding), the retainer 24 is also lowered, and the retainer 24 presses the grinding pad 16 around the workpiece W, which can prevent the edge of the workpiece W from being over-grinded and affects the grinding shape of the workpiece W. In addition, a gap can be generated between the retainer 24 and the grinding pad 16 to prevent the retainer 24 from being worn.

[0043] In addition, as another example, Figure 5As shown in the figure, the retainer pressurizing part 22 (retainer pressurizing top plate part 22a) replaces the hanging parts 26a and 26b and is slidably and closely attached to the shaft part 20c and the head upper side wall part 20b of the head base part 20 via sealing parts 34a and 34b such as O-rings, respectively. The "closely attached" mentioned here requires that the retainer pressurizing part 22 and the head base part 20 are closely attached to the extent that the retainer pressurizing part 22 can slide up and down relative to the head base part 20 by adjusting the pressure in the fourth fluid chamber 28 by the fourth pressure adjustment mechanism 32. Thus, the sealing parts 34a and 34b have the same effect as the hanging parts 26a and 26b, and can replace the hanging parts 26a and 26b. In addition, the hanging parts 26a and 26b may be provided on one of the inner peripheral side and the outer peripheral side of the retainer pressurizing top plate part 22a, and the sealing parts 34a and 34b may be provided on the other side (not shown). Furthermore, a rotation force transmission mechanism (for example, a rotation force transmission pin) or the like that assists in the transmission of the rotation force of the head base portion 20 may be provided together with the sealing members 34 a and 34 b .

[0044] Then, if Figure 3 As shown, the grinding head 12 has 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 including an upper plate 38 and a lower plate 40. The workpiece pressure plate 36 is equivalent to a hard component for fixing the workpiece W during back reference grinding. Therefore, as an example, the upper plate 38 and the lower plate 40 are both made of ceramics, etc., but it is also possible that one or both are made of other materials with a certain degree of flexibility. In this embodiment, as Figure 3 As shown, it has an upper edge portion 38a protruding upward from the outer end portion of the upper plate 38, and the upper plate 38 as a whole is in the shape of a disk with an edge. In addition, the head base portion 20 has a lower disk portion 20d that expands to a predetermined width toward the outer peripheral side on the lower surface of the shaft portion 20c. With this form, the workpiece pressure plate 36 (upper edge portion 38a) is suspended on the lower disk portion 20d of the head base portion 20 via the suspension component 26c on the inner peripheral side, but is not limited to this form. In addition, it is suspended on the head lower side wall portion 22b of the retainer pressure portion 22 on the outer peripheral side via the suspension component 26d. It can also be as follows Figure 4 As shown, the hanging parts 26c and 26d are formed as one body.

[0045] In this way, the workpiece pressure plate 36 is suspended on the head base portion 20 (and the retainer pressure portion 22) via the suspension components 26c and 26d. The suspension components 26c and 26d of the present embodiment are both formed of a diaphragm of a rubber material, and the workpiece pressure plate 36 is configured to move up and down relative to the head base portion 20 (and the retainer pressure portion 22) via the shape change of the suspension components 26c and 26d. Furthermore, when the head base portion 20 rotates, its rotational force is transmitted to the workpiece pressure plate 36 via the suspension component 26c to rotate it. The suspension components 26c and 26d are not limited in structure and material as long as they can suspend the workpiece pressure plate 36 so that it can move up and down as described above. That is, it is not limited to a diaphragm, and it may be, for example, a bellows, etc. Furthermore, it is not limited to a rubber material, and it may be a resin material, a metal material, etc.

[0046] Here, a third fluid chamber 42 is provided between the lower surface of the head base portion 20 (the lower surface of the lower disk portion 20d) and the upper surface of the workpiece pressure plate 36 (the upper surface of the upper plate 38) (and the hanging part 26c). The third fluid chamber 42 can supply and discharge fluid via the third flow path 44 provided with a third pressure adjustment mechanism 46. As a result, the third fluid chamber 42 formed as a closed space can be made to have a positive pressure to lower the workpiece pressure plate 36. On the other hand, the third fluid chamber 42 can be made to have a negative pressure to raise the workpiece pressure plate 36. In the present embodiment, the structure is used in which the fluid is set to air and the air pressure in the third fluid chamber 42 is adjusted, but it is not limited to this structure. For example, the fluid may also be water, oil, etc. The supply path and the discharge path of the third flow path 44 composed of a supply path and a discharge path may be set to the same pipeline or to different pipelines. That is, the number of pipelines constituting the third flow path 44 and other forms are not limited. In the present embodiment, as Figure 3 As shown, as an example, the interior of the shaft portion 20c is formed to be hollow. The hollow portion 45 can be conceptually understood as a part of the third fluid chamber 42, and can also be understood as a part of the third flow path 44. The third pressure regulating mechanism 46 can be exemplified as a fluid compression device or an electromagnetic valve, etc., which is driven and controlled by the control unit 72. A plurality of third pressure regulating mechanisms 46 can also be provided.

[0047] In addition, as another example, Figure 5As shown, the workpiece pressurizing plate 36 (upper edge portion 38a) is provided in a slidable and close manner on the lower plate portion 20d of the head base portion 20 and the head lower side wall portion 22b of the retainer pressurizing portion 22 via sealing members 34c and 34d similar to the aforementioned sealing members 34a and 34b instead of the hanging members 26c and 26d. In addition, a hanging member (26c or 26d) may be provided on one of the inner circumference and the outer circumference of the upper edge portion 38a, and a sealing member (34c or 34d) may be provided on the other (not shown). In addition, a rotational force transmission mechanism (for example, a rotational force transmission pin) or the like that assists in the transmission of the rotational force of the head base portion 20 may be provided together with the sealing members 34c and 34d.

[0048] And, as Figure 3 The above-mentioned different example of the structure in which the workpiece pressing plate 36 is moved up and down by adjusting the pressure in the third fluid chamber 42 as shown in FIG. Figure 6 As shown, the workpiece pressing plate 36 is fixedly arranged on the head base portion 20 (in Figure 6 As an example, the lower plate portion 20d) is moved up and down and rotated together with the up and down movement and rotation of the head base portion 20 driven by the head shaft 18. In this example, it is also possible to Figure 6 As shown, the third fluid chamber 42 as the pressure adjustment space is not necessarily provided. Furthermore, the head base 20 and the workpiece pressing plate 36 (particularly the upper plate 38) may be integrally formed (not shown).

[0049] Furthermore, the grinding head 12 has a backing material 48 below the workpiece pressing plate 36. The backing material 48 is fixed in a manner such that the peripheral portion is sandwiched between the lower surface of the retainer pressing portion 22 (the lower surface of the widened portion 22c) and the upper surface of the retainer 24. The backing material 48 is equivalent to a soft component that fixes the workpiece W during the front reference grinding, and is equivalent to a buffer component that contacts and protects the workpiece W during grinding or conveying the workpiece W. Therefore, as an example, it is configured as a sheet body composed of a flexible resin material or rubber material.

[0050] The backing material 48 has: an adsorption surface 48a, which is opposite to the upper surface Wb of the workpiece W; and a pressing surface 48b, which is the surface on the opposite side of the adsorption surface 48a and is opposite to the workpiece pressing plate 36. When the structure of the grinding head 12 is described with the backing material 48 as the center, the retainer 24 is provided on the outer periphery of the adsorption surface 48a, the retainer pressing portion 22 that can move up and down is provided on the outer periphery of the pressing surface 48b, and the workpiece pressing plate 36 that can move up and down is provided in the central part of the pressing surface 48b so as to be able to contact and separate from the pressing surface 48b (see Fig.11A , Fig. 11B , Fig. 11C ).

[0051] And, although in Figure 3 It cannot be confirmed visually, but refer to Figure 2 A first fluid chamber 50 is provided between the lower surface of the workpiece pressure plate 36 (the lower surface of the lower plate 40) and the upper surface of the backing material 48 (the stamping surface 48b). The first fluid chamber 50 can supply and discharge fluid via the first flow path 52 provided with a first pressure adjustment mechanism 54. In the present embodiment, the fluid is set to air and the air pressure in the first fluid chamber 50 is adjusted, but it is not limited to this structure. For example, the fluid can also be water, oil, etc. The supply path and the discharge path of the first flow path 52 composed of a supply path and a discharge path can be set to the same pipeline or different pipelines. That is, the number of pipelines constituting the first flow path 52 and other forms are not limited. Regarding the first pressure adjustment mechanism 54, it can be exemplified as a fluid compression device or an electromagnetic valve, etc., which is driven and controlled by the control unit 72. A plurality of first pressure adjustment mechanisms 54 can also be provided.

[0052] In addition, as described above, the form of the first flow path 52 is not limited, but in the present embodiment, Figure 3 As shown, the first flow path 52 is configured to extend 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 peripheral side) of the lower plate 40 and the side surface (inner peripheral side) of the retainer pressurizing portion 22 (widened portion 22c). The gap width of the 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 pressurizing portion 22 (widened portion 22c), and the region of the backing material 48 corresponding to the gap region 51 is a clearance region that does not correspond to either the retainer pressurizing portion 22 (retainer 24) or the workpiece pressurizing plate 36 (lower plate 40). Therefore, this area is an area that is not directly pressed by the retainer pressurizing portion 22 and the workpiece pressurizing plate 36 (lower plate 40), but is connected to the first fluid chamber 50 and receives 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 area 51, and the gap area 51 itself may not be provided (both are not shown). Regarding the structure in which the gap area 51 itself is not provided, for example, the following structure can be considered: a sealing member similar to the aforementioned sealing members 34a and 34b is slidably and tightly provided on the side surface (outer peripheral side) of the lower plate 40 and the side surface (inner peripheral side) of the retainer pressurizing portion 22 (widened portion 22c) (not shown).

[0053] According to the above structure, when grinding the workpiece W, Figure 2As shown, the control unit 72 makes the third fluid chamber 42 a vacuum and raises the workpiece pressurizing plate 36, thereby forming the first fluid chamber 50 between the workpiece pressurizing plate 36 and the backing material 48, and then pressurizing the first fluid chamber 50. Thus, the back surface Wb of the workpiece W can be fixed to the soft backing material 48 while applying a grinding pressure to the workpiece W to perform front reference grinding.

[0054] On the other hand, Figure 3 As shown, the control unit 72 pressurizes the inside of the third fluid chamber 42 to lower the workpiece pressurizing plate 36, so that the workpiece pressurizing plate 36 contacts the backing material 48, and makes the inside of the first fluid chamber 50 vacuous or open to the atmosphere so that the workpiece pressurizing plate 36 and the backing material 48 are in close contact, and then further pressurizes the inside of the third fluid chamber 42. Alternatively, Figure 6 In the case of the structure of the embodiment shown, the head shaft 18 is driven to lower the workpiece pressing plate 36 so that the workpiece pressing plate 36 contacts the backing material 48, and the first fluid chamber 50 is evacuated or opened to the atmosphere so that the workpiece pressing plate 36 and the backing material 48 are in close contact, and then a driving force is applied via the head shaft 18 to further lower the workpiece pressing plate 36. Thus, the back side reference grinding can be performed by applying grinding pressure to the workpiece W while the back side Wb of the workpiece W is substantially fixed to the hard workpiece pressing plate 36.

[0055] Here, if Figure 3 As shown, a contact portion 23 is provided to fix the workpiece pressing plate 36 and the retainer pressing portion 22 relatively to each other when the workpiece pressing plate 36 is lowered. The contact portion 23 of the present embodiment is formed as an inclined surface 23a inclined relative to the horizontal direction and the vertical direction at a predetermined position of the retainer pressing portion 22 (the upper surface of the widened portion 22c) and a corresponding predetermined position of the workpiece pressing plate 36 (the outer end of the lower surface of the upper plate 38), but is not limited to this structure. As another example, the contact portion 23 can also be formed as 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. As a result, the grinding head 12 as a whole can be made into a more stable structure through the centering effect. In addition, the contact portion 23 can of course also be formed as a horizontal surface. Furthermore, in the present embodiment, the portion of the retainer pressing portion 22 involving the abutment portion 23 is formed by a component different from the retainer pressing portion 22 body, but may be formed as a part of the retainer pressing portion 22 body by processing the upper surface of the widened portion 22c into a predetermined shape.

[0056] The abutment portion 23 functions as a stopper that restricts movement of the workpiece pressing plate 36 and the retainer pressing portion 22 in a predetermined direction when grinding the workpiece W, and forms a relative positional relationship between the workpiece pressing plate 36 and the retainer pressing portion 22, and further, the structures in the vicinity thereof. As an example, in the present embodiment, when grinding the workpiece W (back reference grinding), when the lower surface of the upper plate 38 (upper edge portion 38a) of the workpiece pressing plate 36 abuts against the upper surface of the widened portion 22c of the retainer pressing portion 22 via the abutment portion 23 formed on the inclined surface 23a, the lower surface of the workpiece pressing plate 36 (lower surface of the lower plate 40) contacts the upper surface (pressing surface 48b) of the backing material 48, and the gap therebetween disappears, and the first fluid chamber 50 disappears in appearance. In this state, the vertical and horizontal movements of the workpiece pressing plate 36 and the retainer pressing portion 22 are restricted, 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, and a predetermined gap is generated between the retainer 24 and the polishing pad 16. Specifically, Figure 3 As shown in FIG. 1 , the lower end surface IIIE of the retainer pressing portion 22 is set to coincide with the lower end surface IIIC of the workpiece pressing plate 36 (the lower end surface IIID of the lower plate 40) in the horizontal direction, so that the lower end surface IIIB of the retainer 24 thinner than the workpiece W is located above the lower end surface IIIA of the workpiece W. Thus, the retainer 24 is prevented from contacting with the polishing pad 16, and the retainer 24 is prevented from being worn.

[0057] 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 the thickness) of the retainer 24, the widened portion 22c, the abutment portion 23, and / or the upper plate 38 (upper edge portion 38a) of the workpiece pressing plate 36. Therefore, as another example, when grinding the workpiece W (back reference grinding), when the lower surface of the upper plate 38 (upper edge portion 38a) of the workpiece pressing plate 36 abuts against the upper surface of the widened portion 22c of the retainer pressing portion 22 via the abutment portion 23, the lower end face IIIB of the retainer 24 is aligned with the lower end face IIIA of the workpiece W in the horizontal direction, or is located below the lower end face IIIA of the workpiece W. In this way, the abutment portion 23 helps to accurately form the height position of the retainer 24, especially the relative positional relationship with the workpiece W, and the workpiece W is accurately ground into a set shape.

[0058] Furthermore, during the pre-surfacing of the workpiece pressing plate 36 and the retainer pressing portion 22 to form the above-mentioned positional relationship, the abutment portion 23 also functions as a stopper for positioning the workpiece pressing plate 36 and the retainer pressing portion 22 relative to each other. Fig.10As shown, by grinding in a state where the workpiece pressing plate 36 and the retainer pressing portion 22 are in contact with each other via the contact portion 23 and are relatively fixed, the lower end surface XE of the retainer pressing portion 22 can be trimmed so that the lower end surface XC of the workpiece pressing plate 36 (the lower end surface XD of the lower plate 40) is aligned in the horizontal direction. The details of the structure will be described later, but it is not Fig.10 The second fluid chamber 56 between the upper plate 38 and the lower plate 40 is connected via the first flow passage 62 as shown in FIG. Figure 8 In the case of a sealed structure of the second fluid chamber 56 as shown, the second fluid chamber 56 may be pressurized or evacuated or opened to the atmosphere for surface finishing, thereby forming the lower end surface XD of the lower plate 40 into a shape different from the horizontal plane.

[0059] In addition, regarding the abutment portion 23, as another example, it is also possible to Figure 7 As shown, at a predetermined position of the retainer pressurizing portion 22 (the upper surface of the widened portion 22c) and a corresponding predetermined position of the workpiece pressurizing plate 36 (the outer end of the lower surface of the upper plate 38), a positioning pin 23b vertically arranged on a horizontal surface and an embedding hole 23c for the positioning pin 23b to be embedded are formed (wherein, Figure 7 As Figure 2 In this example, as shown in FIG. Figure 7 As shown in the figure, a positioning pin 23b is fixed on the side of the retainer pressurizing portion 22, and an embedding hole 23c is provided on the side of the workpiece pressurizing plate 36, but it is also possible to fix the positioning pin 23b on the side of the workpiece pressurizing plate 36, and to provide an embedding hole 23c on the side of the retainer pressurizing portion 22. According to this example, the movement of the workpiece pressurizing plate 36 and the retainer pressurizing portion 22 in a specified direction (particularly in the horizontal direction) can be restricted in the same manner as in the present embodiment, so that a specified gap is generated between the retainer 24 and the polishing pad 16. Moreover, according to this example, the circumferential (horizontal) deviation of the retainer pressurizing portion 22 and the workpiece pressurizing plate 36 can be effectively suppressed, especially during the trimming process, so that the lower end surface XE of the retainer pressurizing portion 22 can be made to coincide with the lower end surface XC of the workpiece pressurizing plate 36 (the lower end surface XD of the lower plate 40) with higher precision. In addition, the size, shape, number, and other forms of the positioning pin 23b are not limited. Furthermore, by forming the abutment portion 23 into an undulating surface or a concave-convex surface, etc., so as to enable the workpiece pressure plate 36 and the retainer pressure portion 22 to be interlocked, the circumferential (horizontal) displacement of the retainer pressure portion 22 and the workpiece pressure plate 36 can be effectively suppressed, especially during the surface finishing process, and the same effect as in the present example (locating pin 23b) can be obtained.

[0060] And, if Figure 3As shown, a 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 workpiece pressurizing plate 36 composed of two layers. In the present embodiment, the lower plate 40 has an upper edge portion 40a protruding upward from the outer end portion similarly to the upper plate 38, and is formed as a whole in a circular basin shape with an edge, thereby forming a space for dividing the second fluid chamber 56, but the present invention is not limited to this form. For example, the space may be formed by forming the lower surface of the upper plate 38 or the upper surface of the lower plate 40 into a concave lens shape or the like. The second fluid chamber 56 can be supplied and discharged through the second flow path 58 provided with the second pressure adjustment mechanism 60. In the present embodiment, the fluid is set as air and the air pressure in the second fluid chamber 56 is adjusted, but the present invention is not limited to this structure, and the fluid may also be water, oil, etc. The supply path and the discharge path of the second flow path 58 composed of the supply path and the discharge path may be set as the same pipeline or different pipelines. That is, the number of pipes and other forms constituting the second flow path 58 are not limited. The second pressure regulating mechanism 60 may be a fluid compression device or a solenoid valve, etc., and is driven and controlled by the control unit 72. A plurality of second pressure regulating mechanisms 60 may be provided.

[0061] Here, if Figure 3 As shown, the lower plate 40 of the present embodiment is formed porous, and the first fluid chamber 50 and the second fluid chamber 56 are connected through a plurality of fine flow passages 62 (first flow passages 62). Therefore, when the workpiece W is ground (back reference grinding), when the workpiece pressing plate 36 and the backing material 48 are brought into contact and integrated, the air bubbles between the workpiece pressing plate 36 and the backing material 48 can be removed from the first flow passage 62 through the second fluid chamber 56 by making the second fluid chamber 56 vacuous, thereby further improving their closeness. The first flow passage 62 can be formed by the lower plate 40 being made of a porous material (porous material), or can be set in a non-porous material in design. The size, shape, number, and other forms of the first flow passage 62 are not limited. In addition, the first flow path 62 formed by the lower plate 40 being composed of a porous material is sometimes connected to the first flow path 52 via the gap area 51, and the first flow path 62 designed to be arranged in a non-porous material can also be configured to be connected to the first flow path 52 or not.

[0062] On the other hand, as another example, Figure 8 As shown, a flow passage 64 (second flow passage 64) that connects the first fluid chamber 50 with the first flow passage 52 is provided on the workpiece pressing plate 36 (lower plate 40) instead of the first flow passage 62 (wherein, Figure 8 As Figure 212 is shown in the figure). Thus, it is also possible to remove the bubbles between the workpiece pressurizing plate 36 and the backing material 48 from the second flow passage 64 through the first flow passage 52 by making the first fluid chamber 50 evacuated, thereby further improving their close adhesion. Figure 8 In the embodiment, the second flow passage 64 may be a groove 64a passing through the lower surface of the lower plate 40, or a hole 64b passing through the interior of the lower plate 40 from the lower surface of the lower plate 40. However, the second flow passage 64 is different from the first flow passage 62, and does not connect the first fluid chamber 50 with the second fluid chamber 56. The size, shape, number, etc. of the second flow passage 64 are not limited. In addition, of course, both the first flow passage 62 and the second flow passage 64 may be provided.

[0063] And, as another example, Fig. 9 As shown, a flow passage 66 (third flow passage 66) is provided on the workpiece pressurizing plate 36 (lower plate 40) to connect the first fluid chamber 50 with the fifth flow passage 68 provided with the fifth pressure regulating mechanism 70, instead of the first flow passage 62 and the second flow passage 64 (wherein, Fig. 9 As Figure 2 Thus, the bubbles between the workpiece pressurizing plate 36 and the backing material 48 can be removed from the third flow passage 66 via the fifth flow passage 68 by using the fifth pressure adjustment mechanism 70 to evacuate the third flow passage 66 via the fifth flow passage 68, thereby further improving their close adhesion.

[0064] In this example, it is sufficient to be configured so that the fluid can be discharged from at least the third flow passage 66 via the fifth flow passage 68 by utilizing the fifth pressure regulating mechanism 70 to make it a vacuum, but it is also possible to supply fluid to the third flow passage 66 and pressurize it. In this case, it is of course also possible to open to the atmosphere. For example, the supply passage and the discharge passage of the fifth flow passage 68 composed of the supply passage and the discharge passage can be set to the same pipeline or to different pipelines. That is, the number of pipelines and other forms constituting the fifth flow passage 68 are not limited. Regarding the fifth pressure regulating mechanism 70, it can be exemplified as a compression device or an electromagnetic valve of the fluid, etc., which is driven and controlled by the control unit 72. The fifth pressure regulating mechanism 70 can also be provided in multiple numbers. In addition, the fluid is not limited, for example, the fluid can also be water, oil, etc., but when the same fluid as the fluid circulating in the first flow passage 52 is selected and applied to the present embodiment, it is set to air.

[0065] Furthermore, in this example, since the third flow passage 66 is not communicated with the first flow passage 52, after the first fluid chamber 50 is evacuated or opened to the atmosphere by the first pressure adjustment mechanism 54 to make the workpiece pressurizing plate 36 (lower plate 40) and the backing material 48 close to each other, the fifth pressure adjustment mechanism 70 is used to make them close to each other, so that the area of ​​the first fluid chamber 50 corresponding to the lower plate 40 can be almost eliminated and the area can be almost separated from the gap area 51. Moreover, in the case where the first flow passage 62 is not communicated with the first flow passage 52, the second pressure adjustment mechanism 60 is used to make the workpiece pressurizing plate 36 (lower plate 40) and the backing material 48 close to each other, so that the area of ​​the first fluid chamber 50 corresponding to the lower plate 40 can be almost eliminated and the area can be almost separated from the gap area 51. Thus, the pressure in the gap area 51 can be adjusted separately from the first fluid chamber 50 by the first pressure adjustment mechanism 54. Therefore, from the above-mentioned state, the first pressure adjustment mechanism 54 can be further used to pressurize the gap area 51 through the first flow path 52 or make the gap area 51 vacuous or open to the atmosphere, so as to adjust the pressing force applied to the area corresponding to the gap area 51, mainly from the edge (peripheral part) of the workpiece W to the surrounding area of ​​the workpiece W. In addition, the area corresponding to the gap area 51 can be arbitrarily set by adjusting the radial width (diameter) of the lower plate 40, the gap width of the gap area 51, and / or the radial width of the retainer pressurizing portion 22 (widening portion 22c), for example, it can also include an area closer to the center of the workpiece W, and it can also be expanded from the surrounding area of ​​the workpiece W. In this way, the pressing force applied to the area corresponding to the gap area 51, such as from the edge of the workpiece W to the surrounding area of ​​the workpiece W, can be adjusted by using the structure of the third flow path 66 or the first flow path 62 not connected to the first flow path 52, thereby bringing a desired influence on the grinding shape of the workpiece W.

[0066] Furthermore, by adjusting the thickness of the upper plate 38 and / or the lower plate 40, or 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 a convex lens, the upper plate 38 and / or the lower plate 40 can be warped upward and / or downward to change their shape by adjusting the pressure in the third fluid chamber 42 and the second fluid chamber 56. The details will be described later.

[0067] Next, the driving unit (not shown) of the grinding head 12 is described. As described above, the driving unit is composed of a vertical movement driving mechanism (not shown) and a rotation driving mechanism (not shown) driven and controlled by the control unit 72, and the grinding head 12 is moved up and down and rotated by moving the head shaft 18 up and down and rotating. Both the vertical movement driving mechanism and the rotation driving mechanism of the driving unit can be composed of well-known mechanisms.

[0068] Specifically, as the driving source of these up-and-down moving drive mechanisms and the rotating drive mechanisms, motors such as servo motors can be used, and as the direct-acting device and the rotating device, spline mechanisms such as ball screw spline mechanisms and rotating ball spline mechanisms can be used. Alternatively, a linear motor in which the driving source and the direct-acting device are integrated can be used, and a linear motor actuator in which the guiding mechanism of the direct-acting device is also integrated can also be used. In this case, a spindle can be used as a rotating device, or a linear motor actuator with a built-in rotating device can be used (both not shown).

[0069] In addition, by appropriately setting a current detector for detecting the load on the motor, an encoder for detecting the rotation speed or rotation angle, a length measuring sensor for detecting the upper and lower intervals of the head base 20, the retainer pressure portion 22, the retainer 24, etc., or the upper and lower intervals between them and the polishing pad 16 as the height position of the polishing head 12, and adjusting the height position of the polishing head 12 based on these detection values, high-precision control can be achieved (not shown in the figure).

[0070] (Grinding device)

[0071] Next, if Figure 3 As shown, the grinding device 10 of the present embodiment is a single-sided grinding device as follows: the workpiece W is held on the lower surface of the grinding head 12 of the present embodiment arranged above the platform 14, and while the workpiece W is pressed against the grinding pad 16 attached to the upper surface of the platform 14, the platform 14 and the grinding head 12 are rotated and relatively slid to grind the lower surface Wa of the workpiece W.

[0072] The platform 14 is formed in a disk shape when viewed from above, and a polishing pad 16 (see Figure 3 ). The platform 14 is provided with a rotation drive mechanism (not shown) and is configured to be rotatable in a horizontal plane around an axis. In addition, a slurry supply unit (not shown) is provided to supply a grinding slurry to the grinding pad 16. Therefore, when grinding the workpiece W, while supplying slurry to the workpiece W, the workpiece W and the grinding pad 16 can be made to slide relative to each other by rotating the grinding head 12 and the platform 14 relative to each other, thereby grinding the lower surface Wa of the workpiece W. As an example, the grinding pad 16 is formed of a polyurethane sheet, a non-woven fabric sheet impregnated with polyurethane, etc., but is not limited thereto.

[0073] (Grinding method)

[0074] Next, the polishing head 12 ( Figure 2 and Figure 3 The polishing method of this embodiment is described with reference to an example of the polishing head 12 shown in FIG.

[0075] First, when grinding the front reference, Figure 2 As shown, the control unit 72 makes the third fluid chamber 42 a vacuum so that the workpiece pressing plate 36 floats upward, and forms a first fluid chamber 50 between the workpiece pressing plate 36 and the backing material 48. The first fluid chamber 50 functions as a closed space for pressurizing the workpiece W, and the control unit 72 then pressurizes the first fluid chamber 50. As a result, the workpiece W can be pressed from above and polishing pressure can be applied to the workpiece W in a state where the lower surface of the workpiece pressing plate 36 is separated from the punching surface 48b of the backing material 48 and the upper surface of the workpiece W is in contact with the suction surface 48a of the backing material 48. As a result, the back surface Wb of the workpiece W can be fixed to the soft backing material 48 and the front 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. Thus, as a guide ring effect, the lateral sliding (radial flying) of the workpiece W can be prevented, and as a retainer effect, the deflection of the polishing pad 16 can be corrected to prevent excessive polishing of the edge portion, or the tension of the backing material 48 can be changed to have a desired effect on the polished shape of the workpiece W. In addition, in the present 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.

[0076] And, if Figure 2 As shown in FIG. 1 , in the case of a structure in which the first fluid chamber 50 and the second fluid chamber 56 are connected, the control unit 72 pressurizes the second fluid chamber 56 to the same pressure as that in the first fluid chamber 50. Figure 8 In the case of a structure in which the first fluid chamber 50 and the second fluid chamber 56 are not communicated with each other as shown, for example, the second fluid chamber 56 is sealed or opened to the atmosphere. In this way, the shape of the lower plate 40 is prevented from changing.

[0077] Through the above control, during the front reference grinding of this embodiment, the control unit 72 raises the workpiece pressing plate 36 and lowers the retainer pressing unit 22, and applies forces in opposite directions to the two structures, thereby Fig.11A As shown in FIG. 1 , a characteristic positional relationship is formed in which the lower end surface XIA of the workpiece pressing plate 36 is located relatively above the lower end surface XIB of the retainer pressing portion 22. The up-and-down movement driving mechanism of the workpiece pressing plate 36 can also be based on Figure 6 The drive of the head shaft 18 shown (the up and down movement drive mechanism of the drive unit) (wherein, Figure 6 This is an example of the state during back-side reference grinding).

[0078] In addition, when each fluid chamber 28, 42, 50, 56 is in the above-mentioned state, by making the first fluid chamber 50 evacuated, the workpiece W can be picked up (adsorbed and lifted up). On the other hand, to unload (peel off) the workpiece W, it is sufficient to introduce air into the first fluid chamber 50 again. That is, according to this embodiment, the backing material 48 can be used as an adsorption disk to fix (hold) and pick up the workpiece W, and it is not formed as a porous material as in the previous structure. Therefore, when picking up and unloading, it is possible to prevent adsorption marks and foreign matter on the workpiece W from mixing into the inside of the polishing head 12.

[0079] Next, during the back reference grinding, if Figure 3 As shown, the control unit 72 pressurizes the inside of the third fluid chamber 42 to lower the workpiece pressurizing plate 36, so that the workpiece pressurizing plate 36 contacts the backing material 48. In this state, the first fluid chamber 50 disappears on the surface, but the control unit 72 makes the inside of the first fluid chamber 50 evacuated or open to the atmosphere so that the workpiece pressurizing plate 36 contacts the backing material 48, and then applies a downward force to the workpiece pressurizing plate 36. Specifically, in Figure 3 In the embodiment shown in FIG. 1 , the third fluid chamber 42 is further pressurized to apply a downward force to the workpiece pressurizing plate 36 . Figure 6 In the case of the structure of the embodiment shown, the head shaft 18 is driven to lower the workpiece pressing plate 36. As described above, after the workpiece pressing plate 36 is brought into contact with the backing material 48, the first fluid chamber 50 is made into a vacuum or opened to the atmosphere to make the workpiece pressing plate 36 and the backing material 48 close to each other. Next, a driving force is applied via the head shaft 18 to further lower the workpiece pressing plate 36, thereby applying a downward force to the workpiece pressing plate 36. As a result, the workpiece W can be pressed from above and a grinding pressure can be applied to the workpiece W in a state where the lower surface of the workpiece pressing plate 36 is brought into contact with the punching surface 48b of the backing material 48 and the upper surface of the workpiece W is brought into contact with the suction surface 48a of the backing material 48. As a result, the back surface Wb of the workpiece W can be substantially fixed to the hard workpiece pressing plate 36 to perform back reference grinding.

[0080] At this time, according to the present embodiment, as described above, when the workpiece pressing plate 36 is lowered, the workpiece pressing plate 36 abuts against the retainer pressing portion 22 and the workpiece pressing plate 36 contacts the backing material 48. In this state, when the back reference grinding is performed, as shown in FIG. Figure 3As shown, the lower end face IIIB of the retainer 24 is located above the lower end face IIIA of the workpiece W fixed to the backing material 48, and a predetermined gap is generated between the retainer 24 and the polishing pad 16. Regarding the back reference grinding, in the nature of grinding according to the shape of the hard component formed on the back side Wb of the workpiece W, that is, the upper surface Wb, the retainer effect of preventing excessive grinding of the edge of the workpiece W caused by the deflection of the polishing pad 16 is relatively low. On the other hand, the wear of the retainer 24 caused by the contact between the retainer 24 and the polishing pad 16 is easy to become a problem. In this regard, according to the present embodiment, the contact between the retainer 24 and the polishing pad 16 can be avoided, and the wear of the retainer 24 can be prevented. In addition, the gap between the retainer 24 and the polishing pad 16 can be set to a small gap to the extent that the wear of the retainer 24 can be prevented, so of course, the guide ring effect can also be obtained. On the other hand, attention is paid to the influence of the retainer effect on the polishing shape of the workpiece W. The retainer 24 is constructed so that no gap is generated between the polishing pad 16. The retainer 24 and the polishing pad 16 are brought into contact (pressed) while polishing, so that the desired polishing shape can be achieved.

[0081] In the present embodiment, the control unit 72 maintains the contact state between the workpiece pressurizing plate 36 and the retainer pressurizing portion 22 by adjusting the pressure in the fourth fluid chamber 28 to a degree that supports the retainer pressurizing portion 22 (self-weight). Specifically, the workpiece pressurizing plate 36 abuts against the retainer pressurizing portion 22 from above to apply a predetermined pressure. Therefore, the control unit 72 usually appropriately depressurizes the fourth fluid chamber 28 in a manner that does not hinder the pressing force of the workpiece pressurizing plate 36 and can maintain the contact state between the workpiece pressurizing plate 36 and the retainer pressurizing portion 22. As a result, a predetermined gap can be generated between the retainer 24 and the polishing pad 16 as described above.

[0082] Furthermore, in the case where the lower plate 40 has a structure in which the first flow passage 62 and the first fluid chamber 50 and the second fluid chamber 56 are connected, the control unit 72 makes the second fluid chamber 56 a vacuum. Thus, bubbles between the workpiece pressurizing plate 36 and the backing material 48 can be removed from the first flow passage 62 via the second fluid chamber 56, and their closeness can be further improved. At this time, in the case of a structure in which the first flow passage 62 is also connected to the first flow passage 52, the first fluid chamber 50 is also made a vacuum. Furthermore, in the case of a structure in which the lower plate 40 has a second flow passage 64 and the first fluid chamber 50 and the second fluid chamber 56 are not connected, the control unit 72 makes the first fluid chamber 50 a vacuum. Thus, bubbles between the workpiece pressurizing plate 36 and the backing material 48 can be removed from the second flow passage 64 via the first flow passage 52, and their closeness can be further improved. At this time, the second fluid chamber 56 can be either a vacuum or open to the atmosphere. Furthermore, in the case where the lower plate 40 has a third flow passage 66, and the first fluid chamber 50 is connected to the fifth flow passage 68 provided with the fifth pressure adjustment mechanism 70 via the third flow passage 66, the control unit 72 uses the fifth pressure adjustment mechanism 70 to make the third flow passage 66 a vacuum. Thus, the bubbles between the workpiece pressurizing plate 36 and the backing material 48 can be removed from the third flow passage 66 via the fifth flow passage 68, further improving their closeness. At this time, the second fluid chamber 56 can be either a vacuum or open to the atmosphere. In this way, by removing the air accumulation between the workpiece pressurizing plate 36 and the backing material 48, the two can be fully close without bumps. As a result, the back side Wb of the workpiece W can be more precisely ground along the shape of the hard workpiece pressurizing plate 36 (lower plate 40) and accurately ground to the back side reference.

[0083] In addition, in the case of a structure having a first flow passage 62 or a third flow passage 66 that is not connected to the first flow passage 52, while maintaining a sufficiently close fit between the workpiece pressure plate 36 and the backing material 48, the first pressure adjustment mechanism 54 is further used to pressurize the gap area 51 through the first flow passage 52 or to make the gap area 51 a vacuum or open to the atmosphere, thereby adjusting the pressing force applied to the area from the edge of the workpiece W to the surrounding area of ​​the workpiece W corresponding to the gap area 51, thereby achieving a desired effect on the grinding shape of the workpiece W.

[0084] Through the above control, during the back reference grinding of this embodiment, the control unit 72 applies force in the direction of lowering the workpiece pressing plate 36 and raising the retainer pressing unit 22, and applies forces in opposite directions to the two structures, thereby forming Fig. 11B As shown in FIG. 1 , the lower end surface XIA of the workpiece pressing plate 36 is aligned with the lower end surface XIB of the retainer pressing portion 22 in the horizontal direction, or Fig. 11CAs shown in FIG. 1 , the lower end surface XIA of the workpiece pressing plate 36 is located relatively below the lower end surface XIB of the retainer pressing portion 22. The vertical movement of the workpiece pressing plate 36 can also be based on Figure 6 The head shaft 18 shown is driven (the vertical movement driving mechanism of the driving part).

[0085] In addition, as described above, by adjusting the thickness of the upper plate 38 and / or the lower plate 40 or using a material with a certain flexibility to form them, or forming the upper plate 38 and / or the lower plate 40 (especially their lower surfaces) into a special shape such as a concave lens or a convex lens, the upper plate 38 and / or the lower plate 40 can be warped upward and / or downward to change their shape by adjusting the pressure in the third fluid chamber 42 and the second fluid chamber 56.

[0086] Thus, during back-side reference grinding, for example, after the second fluid chamber 56 is evacuated and the lower plate 40 is in a desired shape, grinding is performed following the back side Wb of the workpiece W. Furthermore, for example, after the third fluid chamber 42 is evacuated and the upper plate 38 is in a desired shape, the lower plate 40 is adsorbed onto the upper plate 38 whose shape has changed due to the evacuation of the second fluid chamber, so that the shape of the lower plate 40 follows the shape of the upper plate 38, and grinding can also be performed following the back side Wb of the workpiece W. When the third fluid chamber 42 is used to change the shape of the workpiece pressurizing plate 36 (upper plate 38), as long as the workpiece pressurizing plate 36 is configured to move up and down through the upper plate 38, the lower plate 40 can be ground. Figure 6 The head shaft 18 shown in the figure may be driven (the vertical movement driving mechanism of the driving section).

[0087] In this way, when the shape change on the central side of the workpiece W brought about by applying structural changes to the shape of the upper plate 38 and / or the lower plate 40 and the shape change on the peripheral side of the workpiece W brought about by utilizing the first flow passage 62 or the third flow passage 66 that are not connected to the aforementioned first flow passage 52 and the gap area 51 are combined, the grinding shape of the workpiece W can be changed extremely variously, so that it can be ground into the desired shape more accurately.

[0088] According to the present invention, one grinding head can be used for both front reference grinding and back reference grinding. Therefore, it is possible to reduce downtime, reduce equipment costs, and miniaturize and simplify equipment. In addition, the workpiece pressure plate can be separated from the backing material to form a gap, so the backing material can be used as an adsorption disk to fix and pick up the workpiece. Therefore, it is not necessary to provide adsorption holes in the backing material, and as a result, it is possible to prevent adsorption marks and foreign matter on the workpiece from mixing into the interior of the grinding head.

Claims

1. A grinding head, which is fixed to a head shaft that can move up and down and rotate and is arranged to be able to move up and down and rotate, and the grinding head grinds the workpiece while holding the workpiece to rotate the workpiece and pressing the workpiece against a grinding pad, characterized in that: The grinding head has: A backing material having an adsorption surface facing the upper surface of the workpiece and a stamping surface on the opposite side of the adsorption surface; a workpiece pressing plate, which is disposed at the center of the pressing surface in a manner capable of contacting and separating from the pressing surface and capable of moving up and down; a first fluid chamber disposed between the workpiece pressing plate and the backing material; and a first pressure regulating mechanism for regulating the pressure inside the first fluid chamber, The control unit controls the switching between the front reference grinding and the back reference grinding. In the front reference grinding, the interior of the first fluid chamber is pressurized, thereby pressing the workpiece from above in a state where the lower surface of the workpiece pressing plate is separated from the punching surface of the backing material and the upper surface of the workpiece is in contact with the adsorption surface of the backing material. During the back-side reference grinding, the interior of the first fluid chamber is made into a vacuum or opened to the atmosphere and a downward force is applied to the workpiece pressure plate, thereby pressing the workpiece from above with the lower surface of the workpiece pressure plate in contact with the stamping surface of the backing material and the upper surface of the workpiece in contact with the adsorption surface of the backing material.

2. The grinding head according to claim 1, characterized in that: The grinding head also has: a retainer disposed on the outer periphery of the adsorption surface; and A retainer pressing portion, which is disposed on the outer periphery of the punching surface and is movable up and down, The grinding head is configured such that, by the control unit applying forces in opposite directions upward and downward to the retainer pressure portion and the workpiece pressure plate, grinding is performed in a state where the lower end face of the workpiece pressure plate is located relatively above the lower end face of the retainer pressure portion in the front reference grinding, and grinding is performed in a state where the lower end face of the workpiece pressure plate is horizontally aligned with the lower end face of the retainer pressure portion, or the lower end face of the workpiece pressure plate is located relatively below the lower end face of the retainer pressure portion in the back reference grinding.

3. The grinding head according to claim 2, characterized in that: The grinding head has an abutment portion for abutting and relatively fixing the workpiece pressing plate and the retainer pressing portion, and the abutment portion functions as a stopper that restricts movement of the workpiece pressing plate and the retainer pressing portion in a predetermined direction to form a relative positional relationship when grinding the workpiece.

4. The grinding head according to claim 3, characterized in that: The polishing head is configured such that, during the back surface reference polishing, when the workpiece is pressed against the polishing pad in a state where the workpiece pressing plate and the holder pressing portion are in contact with each other via the contact portion, a gap is formed between the holder and the polishing pad.

5. The grinding head according to claim 1 or 2, characterized in that: The workpiece pressure plate is composed of two layers including an upper plate and a lower plate. The grinding head also has: a second fluid chamber located between the upper plate and the lower plate; and a second pressure regulating mechanism for regulating the pressure inside the second fluid chamber, The lower plate has a flow path that connects the first fluid chamber and the second fluid chamber.

6. The grinding head according to claim 5, characterized in that: The flow path is formed by the lower plate being made of a porous material.

7. The grinding head according to claim 1 or 2, characterized in that: The workpiece pressing plate has a flow passage that connects the first fluid chamber and a first flow passage provided with the first pressure regulating mechanism.

8. The grinding head according to claim 7, characterized in that: The flow passage is a groove formed on the lower surface of the workpiece pressing plate.

9. The grinding head according to claim 1 or 2, characterized in that: The workpiece pressing plate has a flow passage that connects the first fluid chamber with a fifth flow passage provided with a fifth pressure regulating mechanism. The fifth pressure regulating mechanism is configured to be able to evacuate at least the flow channel via the fifth flow channel.

10. The grinding head according to claim 1 or 2, characterized in that: The grinding head also has a head base portion fixed to the head shaft. The workpiece pressing plate is fixed to the head base portion and moves up and down by the driving of the head shaft. The control unit controls the workpiece pressing plate to be forced downward by applying a driving force for lowering the workpiece pressing plate via the head shaft during the back surface reference grinding. or, The workpiece pressure plate is configured to be suspended from the head base or slidably fitted to the head base, and the workpiece pressure plate moves up and down by adjusting the pressure inside the third fluid chamber provided between the head base and the workpiece pressure plate by a third pressure adjustment mechanism. The control unit performs control so as to apply a downward force to the workpiece pressing plate by pressurizing the interior of the third fluid chamber during the back surface reference grinding.

11. A grinding device comprising the grinding head according to claim 1 or 2.

12. A grinding method, wherein a workpiece held by a grinding head is pressed against a grinding pad for grinding, wherein the grinding head comprises: a backing material having an adsorption surface opposite to the upper surface of the workpiece and a pressing surface on the opposite side of the adsorption surface; and a workpiece pressing plate, which is arranged at the central part of the pressing surface in a manner capable of contacting and separating with the pressing surface and can move up and down, It is characterized in that This grinding method switches between front reference grinding and back reference grinding. In the front reference grinding, the workpiece pressing plate is raised to form a closed space between the workpiece pressing plate and the backing material, and the closed space is pressurized, thereby pressing the workpiece from above in a state where the lower surface of the workpiece pressing plate is separated from the punching surface of the backing material and the upper surface of the workpiece is in contact with the adsorption surface of the backing material. In the back-side reference grinding, the enclosed space is made into a vacuum or opened to the atmosphere, and a downward force is applied to the workpiece pressure plate, thereby pressing the workpiece from above with the lower surface of the workpiece pressure plate in contact with the stamping surface of the backing material and the upper surface of the workpiece in contact with the adsorption surface of the backing material.

13. The grinding method according to claim 12, characterized in that: The grinding head also has: a retainer disposed on the outer periphery of the adsorption surface; and A retainer pressing portion, which is disposed on the outer periphery of the punching surface and is movable up and down, The grinding method uses the grinding head, during the front reference grinding, the retainer pressing portion is lowered to press the grinding pad around the workpiece with the retainer, and during the back reference grinding, a gap is formed between the lower end surface of the retainer and the grinding pad.

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