Processing method of the workpiece

Abstract

To provide a processing method which enables reduction of processed waste adhering to a polished surface of a workpiece after polishing of the workpiece.SOLUTION: A workpiece processing method includes: a processing step in which a polishing pad 26, a processing tool which grinds or polishes, is placed in contact with a workpiece 100 held by a holding table to process the workpiece while being pressed; and a retreat step in which the polishing pad 26, the processing tool, and the workpiece 100 are relatively separated from each other in a horizontal direction at a predetermined speed in a state that the polishing pad 26, the processing tool, is in contact with the workpiece 100 to reduce a contact area, where the polishing pad 26, the processing tool, contacts with the workpiece 100, gradually.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a processing method for polishing a workpiece. [Background technology]

[0002] BACKGROUND ART A polishing method for polishing a workpiece is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-166861 Summary of the Invention [Problem to be solved by the invention]

[0004] When a workpiece is polished with a polishing pad, there is a problem that processing debris (polishing debris) adheres to the polished surface of the workpiece during the polishing process. In particular, when a workpiece is polished with a dry polishing pad, there is a problem that processing debris easily adheres to the workpiece.

[0005] The present invention has been made in view of the above problems, and its object is to provide a processing method that can reduce processing debris adhering to the polished surface of a workpiece after the workpiece has been polished. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, a method for processing a workpiece of the present invention is a method for processing a workpiece, comprising: a processing step of bringing a grinding or polishing tool into contact with the workpiece held on a holding table and processing the workpiece while pressing the tool against the workpiece; After the processing step is performed, With the machining tool in contact with the workpiece, the machining tool and the workpiece are moved relatively apart in the horizontal direction at a predetermined speed, gradually reducing the contact area where the machining tool comes into contact with the workpiece. Then, the workpiece on the holding table is separated from the machining tool, and machining is completed. and an evacuation step.

[0007] The retracting step may be performed while relatively adjusting the vertical distance between the holding table and the machining tool so that the load caused by the pressing of the machining tool on the contact area becomes a desired load. [Effects of the Invention]

[0008] The present invention can reduce the amount of processing debris adhering to the polished surface of a workpiece after the workpiece has been polished. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing an example of the configuration of a processing device for carrying out a method for processing a workpiece according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a main part of the processing apparatus of FIG. [Figure 3] FIG. 3 is a flowchart showing an example of a processing procedure of the method for processing a workpiece according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view illustrating the retracting step of FIG. [Figure 5] FIG. 5 is a graph illustrating a method for processing a workpiece according to the second embodiment. [Figure 6] FIG. 6 is a graph illustrating a method for processing a workpiece according to the second embodiment. [Figure 7] FIG. 7 is a diagram showing an example of retraction step control data used in the method for machining a workpiece according to the second embodiment. [Figure 8] FIG. 8 is a diagram illustrating the effects of the method for processing a workpiece according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0011] [Embodiment 1] A method for processing a workpiece according to a first embodiment of the present invention will be described with reference to the drawings. First, a processing apparatus 1 for performing the method for processing a workpiece according to the first embodiment will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of the configuration of the processing apparatus 1 for performing the method for processing a workpiece according to the first embodiment. FIG. 2 is a cross-sectional view showing a main part of the processing apparatus 1 of FIG. 1. The processing apparatus 1 is a polishing apparatus for polishing a workpiece 100, and as shown in FIG. 1, includes a holding table 10, a processing unit 20, a table moving unit 30, a processing feed unit 40, a load sensor 50, and a control unit 60.

[0012] In the first embodiment, the workpiece 100 to be polished by the processing apparatus 1 is, for example, a disk-shaped semiconductor device wafer or optical device wafer made of a base material such as silicon, sapphire, silicon carbide (SiC), or gallium arsenide. The workpiece 100 may or may not have dividing lines or devices formed on its front surface 101. The workpiece 100 has a back surface 102 opposite the front surface 101 as the surface to be processed (the surface to be polished), and a protective member for protecting the front surface 101 may be attached to the back surface 101. The present invention is not limited to this, and the workpiece 100 may also be a rectangular package substrate having a plurality of devices sealed with resin, a ceramic plate, a glass plate, or the like.

[0013] As shown in FIGS. 1 and 2 , the holding table 10 includes a disk-shaped frame 11 having a recess formed therein and a disk-shaped suction unit 12 fitted into the recess. The frame 11 is formed in a disk shape from stainless steel or the like. The suction unit 12 is formed from a porous ceramic containing alumina and has numerous porous holes. The suction unit 12 is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The upper surface of the suction unit 12 of the holding table 10 is a holding surface 13 on which a workpiece 100 is placed and which suction-holds the placed workpiece 100. The holding surface 13 suction-holds the front surface 101 of the placed workpiece 100, for example, with the back surface 102, which is the surface to be processed, facing upward.

[0014] In embodiment 1, as shown in FIG. 2, the holding surface 13 of the holding table 10 and the upper surface of the frame body 11 are formed into a conical shape with a slightly lower outer periphery and a vertex at the center 14, which is the center of rotation of the holding table 10, but the present invention is not limited to this and they may be formed flat.

[0015] The holding table 10 is provided so as to be movable in the Y-axis direction, which is one horizontal direction, by a table moving unit 30. The holding table 10 is connected to a rotary drive source (not shown), and is provided so as to be rotatable around a predetermined rotation axis passing through the center 14 of the holding table 10 by the rotary drive source (not shown).

[0016] Further, below the holding table 10, a tilt adjustment unit 15 is provided which tilts the rotation axis of the holding table 10 with respect to the Z-axis direction which is parallel to the vertical direction. The tilt adjustment unit 15 provided on the holding table 10 is used when adjusting the tilt of the holding surface 13 of the holding table 10. In the first embodiment, the tilt adjustment units 15 are arranged at a plurality of locations (e.g., three locations) at equal intervals (e.g., 120-degree intervals) in the circumferential direction. The tilt adjustment unit 15 is formed, for example, by an electric cylinder or an air cylinder in which a rod can move in the Z-axis direction from within the cylinder, but the present invention is not limited to this and may be formed, for example, by a piezoelectric element which expands and contracts in the Z-axis direction.

[0017] The processing unit 20 is a polishing unit that polishes the workpiece 100 held on the holding table 10, and as shown in Figures 1 and 2, it comprises a polishing pad 26 attached to a mount 21, which is an example of a processing tool according to the present invention, a spindle 22, a spindle housing 23, a holder 24, and a polishing liquid supply source 25.

[0018] The polishing pad 26 is an example of a processing tool according to the present invention. The mount 21 is formed in a disk shape, and the polishing pad 26 for polishing the workpiece 100 is disposed on one surface. The spindle 22 is formed in a cylindrical shape, and the mount 21 is fixed to the lower end thereof, and the polishing pad 26 is attached to the lower surface of the mount 21. The spindle 22 rotates about an axis parallel to the Z-axis direction, which is the vertical direction. The mount 21 attached to the lower end of the spindle 22 is rotated by the spindle 22 about an axis parallel to the Z-axis direction, and the polishing pad 26 contacts and presses against the back surface 102 of the workpiece 100 held on the holding table 10, thereby polishing the back surface 102 of the workpiece 100 with the polishing pad 26. The polishing liquid supply source 25 supplies polishing liquid to the polishing pad 26 through a polishing liquid flow path (not shown) extending in the Z-axis direction from the inside of the mount 21 to the inside of the spindle 22.

[0019] In the first embodiment, the polishing pad 26 is made of, for example, a nonwoven fabric or an elastic resin such as urethane. The polishing pad 26 may or may not contain a fixed abrasive. In the first embodiment, the processing unit 20 may polish the back surface 102 of the workpiece 100 using the polishing pad 26 while supplying a slurry containing abrasive grains as the polishing liquid from the polishing liquid supply source 25. Alternatively, the polishing pad 26 containing fixed abrasive grains may polish the back surface 102 of the workpiece 100 while supplying pure water as the polishing liquid from the polishing liquid supply source 25. Alternatively, the polishing pad 26 may perform chemical mechanical polishing (CMP) while supplying an alkaline polishing liquid as the polishing liquid from the polishing liquid supply source 25. Alternatively, the polishing pad 26 may perform dry polishing of the back surface 102 of the workpiece 100 without supplying a polishing liquid from the polishing liquid supply source 25.

[0020] The spindle housing 23 exposes the lower end of the spindle 22 and accommodates the entire spindle 22 except for the lower end, allowing the spindle 22 to be inserted therethrough. The spindle housing 23 supports the spindle 22 rotatably about an axis parallel to the Z-axis direction. The holder 24 supports and accommodates the spindle housing 23. A processing feed unit 40 is connected to the side of the holder 24. The mount 21, spindle 22, spindle housing 23, and polishing pad 26 of the processing unit 20 are provided so as to be movable in the Z-axis direction, which is the processing feed direction (polishing feed direction), by the processing feed unit 40 via the holder 24.

[0021] The table moving unit 30 is provided below the holding table 10 and extends in the Y-axis direction. By moving the holding table 10 along the Y-axis direction relative to the processing unit 20, the processing unit 20 including the polishing pad 26 and the workpiece 100 held on the holding table 10 are moved relatively toward or away from each other in the horizontal direction at a predetermined speed. The processing feed unit 40 moves the mount 21, spindle 22, spindle housing 23, and polishing pad 26 of the processing unit 20 via the holder 24 along the processing feed direction, thereby moving the polishing pad 26 relatively toward or away from the workpiece 100 held on the holding table 10 in the vertical direction at a predetermined speed. Note that this vertical direction also includes the direction perpendicular to the holding surface 13 of the holding table 10.

[0022] The table moving unit 30 and the processing feed unit 40 each include a well-known ball screw rotatably mounted about its axis, a well-known pulse motor that rotates the ball screw about its axis, and a well-known guide rail that supports the holding table 10 or the processing unit 20 so that it can move freely in the Y-axis or Z-axis direction. The table moving unit 30 and the processing feed unit 40 each include a well-known position detector that detects the position of the holding table 10 or the processing unit 20 in the Y-axis or Z-axis direction, and outputs the position detected by the position detector to the control unit 60.

[0023] As shown in FIGS. 1 and 2, the load sensor 50 includes a table load sensor 51 and a holder load sensor 52. The table load sensor 51 is attached to the underside of the frame 11 of the holding table 10 by screwing it via a ring member. The table load sensors 51 are attached to a plurality of locations (e.g., three locations) at equal intervals (e.g., 120-degree intervals) around the circumferential direction of the holding table 10. The holder load sensor 52 is attached to the underside of the holder 24 of the processing unit 20 by screwing it via a ring member. The holder load sensors 52 are attached to a plurality of locations (e.g., three locations) at equal intervals (e.g., 120-degree intervals) around the circumferential direction of the holder 24. The table load sensor 51 and the holder load sensor 52 measure the loads acting on the holding table 10 and the processing unit 20, respectively, when the polishing pad 26 is pressed against the workpiece 100 on the holding surface 13 of the holding table 10 by the polishing feed of the processing feed unit 40, and output the measured values of the loads (actual measured values) to the control unit 60. The table load sensor 51 and the holder load sensor 52 are configured, for example, with a dynamometer using a piezoelectric element. It is sufficient to have at least one of the table load sensor 51 and the holder load sensor 52.

[0024] The control unit 60 controls the operation of each component of the processing apparatus 1 to cause the processing apparatus 1 to perform a polishing process by the processing unit 20, including the workpiece processing method according to the first embodiment. Based on the position of the holding table 10 in the Y-axis direction acquired from the table moving unit 30, the control unit 60 calculates the relative positional relationship between the polishing pad 26 attached to the mount 21 and the back surface 102 of the workpiece 100 on the holding table 10 in a direction parallel to the holding surface 13, and calculates the area of the contact region between the polishing pad 26 and the back surface 102 of the workpiece 100 when they are in contact with each other, based on the size of the polishing pad 26 and the size of the workpiece 100, both of which have been registered in advance in the control unit 60.

[0025] Based on the position of the processing unit 20 in the Z-axis direction acquired from the processing feed unit 40, the control unit 60 calculates the relative positional relationship (vertical distance) in the vertical direction between the polishing pad 26 attached to the mount 21 and the back surface 102 of the workpiece 100 on the holding table 10. The relative relationship in the vertical direction refers to the distance between the surface of the polishing pad 26 attached to the mount 21 and the back surface 102 of the workpiece 100. After performing processing step 1001, which will be described later, the lower surface of the polishing pad 26 is in contact with the back surface 102 of the workpiece 100. Therefore, even if the processing feed unit 40 performs processing feed in the Z-axis direction, the distance between the lower surface of the polishing pad 26 and the back surface 102 of the workpiece 100 does not change, and the polishing pad 26 is distorted by its elastic force and pressed into the workpiece 100, thereby changing the load.

[0026] Based on the polishing conditions input by the operator from the input unit, the control unit 60 calculates the position of the processing unit 20 in the Z-axis direction when the load caused by the pressure of the polishing pad 26 attached to the mount 21 applied to the contact area between the polishing pad 26 and the back surface 102 of the workpiece 100 when the polishing pad 26 polishes the back surface 102 of the workpiece 100 becomes a desired load. Note that, since the temperature of the space where polishing is performed, the state of the mount 21, the polishing liquid, the thickness of the workpiece 100, etc. change depending on the polishing conditions, the control unit 60 calculates the position of the processing unit 20 in the Z-axis direction taking these into consideration.

[0027] In the first embodiment, the control unit 60 includes a computer system. The computer system included in the control unit 60 includes an arithmetic processing device having a microprocessor such as a CPU (Central Processing Unit), a storage device having memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an input / output interface device. The arithmetic processing device of the control unit 60 performs arithmetic processing in accordance with a computer program stored in the storage device of the control unit 60, and outputs control signals for controlling the machining device 1 to each component of the machining device 1 via the input / output interface device of the control unit 60.

[0028] The processing apparatus 1 further includes a cassette placement section (not shown) and a transport unit (not shown). The cassette placement section is a placement table on which a cassette 70, which is a container for accommodating a plurality of workpieces 100, is placed. The transport unit (not shown) transports the workpieces 100 before processing from inside the cassette 70 onto the holding surface 13 of the holding table 10, and transports the processed workpieces 100 from the holding surface 13 of the holding table 10 into the cassette 70.

[0029] The processing device 1 further includes a display unit (not shown). The display unit (not shown) is provided on a cover (not shown) of the processing device 1 with the display surface facing outward, and displays a screen for setting the processing conditions of the processing device 1, a screen showing the processing results, etc., so that the operator can see them. The display unit is configured with a liquid crystal display device or the like. The display unit is provided with an input unit (not shown) that the operator uses to input command information related to the processing conditions of the processing device 1 and the display of images. The input unit provided on the display unit is configured with at least one of a touch panel provided on the display unit and a keyboard or the like.

[0030] Next, this specification will explain the processing of a workpiece processing method according to embodiment 1 with reference to the drawings. The processing of the workpiece processing method according to embodiment 1 is performed by a processing device 1. FIG. 3 is a flowchart showing an example of the processing procedure of the workpiece processing method according to embodiment 1. FIG. 4 is a cross-sectional view illustrating the retraction step 1002 in FIG. 3. As shown in FIG. 3, the workpiece processing method according to embodiment 1 includes a processing step 1001 and a retraction step 1002.

[0031] In the processing step 1001, the control unit 60 brings the polishing pad 26 side of the rotating mount 21 into contact with the workpiece 100 held on the holding table 10 and performs polishing while pressing the workpiece 100.

[0032] In processing step 1001, first, the control unit 60 controls the transport unit (not shown) to remove the workpiece 100 before polishing from the cassette 70 and transport it onto the holding surface 13 of the holding table 10 with the back surface 102, which is the surface to be polished, facing upward. Negative pressure is then introduced onto the holding surface 13 of the holding table 10 from a vacuum suction source (not shown) via a vacuum suction path (not shown), and the front surface 101 side of the workpiece 100 before polishing is suction-held by the holding surface 13 of the holding table 10.

[0033] In the processing step 1001, the control unit 60 then controls the tilt adjustment unit 15 to adjust the tilt of the holding surface 13 of the holding table 10, and then controls the rotary drive source to rotate the holding table 10 and the workpiece 100 on the holding table 10 around a predetermined rotation axis, while rotating the spindle 22 to rotate the mount 21 attached to the lower end of the spindle 22, and then the polishing pad 26 attached to the mount 21 is brought into contact with the workpiece 100 on the holding table 10 by the processing feed unit 40 and pressed against it, thereby polishing the back surface 102 of the workpiece 100 with the polishing pad 26.

[0034] In processing step 1001, the control unit 60 uses the processing feed unit 40 to position the processing unit 20 at a position in the Z-axis direction calculated based on the polishing processing conditions and load setting values input in advance by the operator from the input unit, and presses the polishing pad 26 against the back surface 102 of the workpiece 100 to perform polishing. In processing step 1001, the control unit 60 acquires a load measurement value from the load sensor 50, and controls the position of the processing unit 20 in the Z-axis direction using the processing feed unit 40 so that the load measurement value acquired from the load sensor 50 approaches the load setting value, thereby adjusting the vertical distance between the upper surface of the polishing pad 26 and the workpiece 100 on the holding table 10, and adjusting the load pressing the polishing pad 26 against the back surface 102 of the workpiece 100.

[0035] The retreat step 1002 is a step in which, after the processing step 1001 has been performed for a predetermined time, the control unit 60 gradually moves the polishing pad 26 attached to the mount 21 and the workpiece 100 away from each other in the horizontal direction at a predetermined speed while the polishing pad 26 is in contact with the workpiece 100 held on the holding table 10, thereby gradually reducing the contact area between the polishing pad 26 and the workpiece 100.

[0036] Here, the predetermined speed may be any speed that is sufficiently faster than a speed that is too slow to significantly reduce the efficiency of the polishing process, and yet sufficiently slower than a speed that is too fast to generate large amounts of frictional heat or significantly adversely affect the quality of the polishing process between the polishing pad 26 attached to the mount 21 and the back surface 102, which is the surface to be polished, of the workpiece 100. In the retraction step 1002, the speed at which the polishing pad 26 and the workpiece 100 are moved relatively apart in the horizontal direction may be changed, but it is preferable to perform the retraction step 1002 at a generally constant speed, as this stabilizes the effect brought about by the retraction step 1002.

[0037] 4, in the retracting step 1002, the control unit 60 controls the rotation drive source subsequent to the processing step 1001 to rotate the holding table 10 and the workpiece 100 on the holding table 10 around a predetermined rotation axis, and rotates the spindle 22 to rotate the mount 21 attached to the lower end of the spindle 22, while moving the holding table 10 by the table moving unit 30 in the direction away from the polishing pad 26 along the Y-axis direction (the retracting direction). In the retracting step 1002, as shown in FIG. 4, the contact area of the polishing pad 26 with the back surface 102, which is the surface to be polished of the workpiece 100 held by the holding table 10, gradually decreases.

[0038] In the retraction step 1002, after the control unit 60 has completely or by a predetermined distance moved the workpiece 100 on the holding table 10 away (retracted) from the polishing pad 26, i.e., after the contact area between the polishing pad 26 and the workpiece 100 on the holding table 10 has decreased to zero or a predetermined amount, the control unit 60 stops the movement of the holding table 10 by the table moving unit 30, further raises the polishing pad 26 vertically by the processing feed unit 40 so as not to interfere when the workpiece 100 is transported from the holding table 10, stops the rotation of the holding table 10 and the workpiece 100 on the holding table 10 by the rotary drive source, and terminates the polishing processing by the processing unit 20.

[0039] In the processing method of the workpiece according to the first embodiment having the above-described configuration, by performing the retraction step 1002, the polishing pad 26 is positioned above the workpiece 100 even after the processing step 1001 is completed, thereby reducing the possibility that the adhering processing debris (polishing debris) will fall onto and adhere to the back surface 102, which is the surface to be polished of the workpiece 100. In addition, the polishing pad 26 moves relatively in the outer circumferential direction of the workpiece 100 while rubbing the surface to be polished of the workpiece 100 with the polishing pad 26 moving away from the workpiece 100, so that the processing debris (polishing debris) adhering to the surface to be polished can be removed. Therefore, no matter what polishing pad 26 or polishing liquid is used for polishing, and particularly even when the workpiece 100 is polished dry without using a polishing liquid and using a polishing pad 26 to which processing debris (polishing debris) is likely to adhere in conventional methods, the effect of being able to reduce the processing debris (polishing debris) adhering to the back surface 102, which is the surface to be polished of the workpiece 100, after polishing the workpiece 100 is achieved.

[0040] [Embodiment 2] A method for processing a workpiece according to a second embodiment of the present invention will be described with reference to the drawings. Figures 5 and 6 are graphs illustrating the method for processing a workpiece according to the second embodiment. Figure 7 is a diagram showing an example of retraction step control data 210 used in the method for processing a workpiece according to the second embodiment. In Figures 5, 6, and 7, the same parts as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0041] FIG. 5 is a graph showing the retraction step 1002 of the first embodiment. The dashed line 201 indicates the load measured by the load sensor 50 being maintained constant during the retraction step 1002. The solid line 202 indicates the area of the contact region between the polishing pad 26 and the rear surface 102 of the workpiece 100 and the value of the load acting on the contact region during the retraction step 1002. As shown by the solid line 202 in FIG. 5, the load acting on the contact region between the polishing pad 26 and the rear surface 102 of the workpiece 100 is such that the measured load value increases as the area of the contact region decreases. Here, the area of the contact region on the horizontal axis of FIG. 5 is expressed as a relative ratio, with the area of the contact region during the processing step 1001 being set to 100%. Note that the solid line 202 in FIG. 5 is an example of the correlation between the area of the contact region and the measured load, and varies depending on the polishing processing conditions, etc.

[0042] In other words, if the value measured by the load sensor 50 is controlled to be constant during the retraction step 1002, as in the normal processing step 1001, the contact area of the polishing pad 26 in contact with the workpiece 100 is reduced, and the load applied to the contact area actually increases. Depending on the polishing conditions, even if the load applied to the contact area increases, there may be cases where surface burning or tape burning (protective member burning), which would burn the polished surface of the workpiece 100, does not occur, and in such cases, there is no problem with embodiment 1.

[0043] 6 is a graph showing a second embodiment in which the load measurement value of the load sensor 50 is reduced when the retraction step 1002 is performed. The dashed line 204 shows the gradual reduction in the load measured by the load sensor 50 during the retraction step 1002. The solid line 203 shows the value of the load applied to the contact area between the polishing pad 26 and the rear surface 102 of the workpiece 100 during the retraction step 1002. The load applied to the contact area between the polishing pad 26 and the rear surface 102 of the workpiece 100, shown by the solid line 203, is maintained constant even as the area of the contact area decreases, as shown by the solid line 203, because the processing feed unit 40 increases the vertical distance between the polishing pad 26 and the workpiece 100 and weakens the pressing force against the workpiece 100 so that the load measurement value of the load sensor 50 gradually decreases.

[0044] In this way, the retracting step 1002 according to the second embodiment is performed by the control unit 60 of the processing apparatus 1 while adjusting the vertical distance between the holding table 10 and the polishing pad 26 to relatively widen so that the load measurement value by the load sensor 50 decreases in accordance with a decrease in the area of the contact region. For example, in the retracting step 1002 according to the second embodiment, the control unit 60 of the processing apparatus 1 adjusts the vertical distance between the holding table 10 and the polishing pad 26 of the mount 21 to relatively widen when the load acting on the contact region exceeds a predetermined threshold, thereby controlling the load acting on the contact region to be equal to or less than the threshold.

[0045] Furthermore, in the retracting step 1002 according to the second embodiment, the control unit 60 of the processing apparatus 1 can relatively adjust the vertical distance between the holding table 10 and the polishing pad 26 so that the load applied to the contact area becomes a desired constant load from the time when the processing step 1001 is performed until the completion of the retracting step 1002. For example, the retracting step 1002 according to the second embodiment can be performed by the control unit 60 of the processing apparatus 1 controlling the load applied by the processing feed unit 40 pressing the polishing pad 26 so that the load measurement value by the load sensor 50 gradually decreases from the time when the processing step 1001 is performed and the area of the contact area becomes approximately zero.

[0046] In the second embodiment, the storage unit of the control unit 60 of the machining apparatus 1 stores the retraction step control data 210 shown in Fig. 7, which is the processing condition for the retraction step 1002. As shown in Fig. 7, the retraction step control data 210 is data that compares the position of the holding table 10 in the Y-axis direction with the position of the machining unit 20 in the Z-axis direction so that the load applied to the contact area is constant for each elapsed time from the start of the retraction step 1002.

[0047] 7, the control unit 60 of the processing apparatus 1 controls the table moving unit 30 to control the position of the processing unit 20 in the Z-axis direction by the processing feed unit 40 in accordance with a reduction in the area of the contact region between the polishing pad 26 and the back surface 102 of the workpiece 100, thereby adjusting the vertical distance between the upper surface of the polishing pad 26 and the workpiece 100 on the holding table 10, thereby controlling the load due to the pressure of the polishing pad 26. This makes it possible to control the load applied to the contact region during the execution of the retraction step 1002 to a desired load.

[0048] The method for generating the retraction step control data 210 is, for example, as follows. First, the area of the contact region that changes in accordance with the movement of the machining unit 20 in the Y-axis direction is calculated, and the optimal measurement value of the load sensor 50 is determined in accordance with the Y-axis position of the machining unit 20, for example, by setting the load measurement value of the load sensor 50 to be halved when the contact area is halved. Next, a machining step 1001 in which the workpiece 100 is actually machined and a retraction step 1002 are performed while monitoring the measurement value of the load sensor 50. In the retraction step 1002, the position in the Z-axis direction is adjusted as needed during machining so that the optimal measurement value of the load sensor 50 is obtained in accordance with the position of the machining unit 20 in the Y-axis direction. Through this experiment, the Z-axis position of the machining unit 20 is obtained for each elapsed time since the start of the retraction step 1002.

[0049] Alternatively, the retraction step control data 210 may not record the Z-axis position of the machining unit 20 for each elapsed time since the start of the retraction step 1002, but may define only the correlation between the Y-axis position of the machining unit 20 and the corresponding optimal measurement value of the load sensor 50. In this case, the Z-axis position of the machining unit 20 for each elapsed time since the start of the retraction step 1002 is adjusted while the retraction step 1002 is being performed so that the measurement value of the load sensor 50 becomes the load defined in the retraction step control data 210.

[0050] The workpiece processing method according to the second embodiment having the above-described configuration has the same functions as those of the first embodiment, and further includes the following: the retraction step 1002 is performed by the control unit 60 of the processing apparatus 1 while adjusting the vertical distance between the holding table 10 and the polishing pad 26 so that the load caused by the pressure of the polishing pad 26 on the contact area becomes a desired load. Therefore, the workpiece processing method according to the second embodiment has the same effects as those of the first embodiment, and further reduces the risk of the load pressing the polishing pad 26 against the back surface 102 of the workpiece 100 increasing and becoming excessive. This reduces the risk of surface burn on the back surface 102 of the workpiece 100 that may occur if the load becomes excessive, and prevents tape burn (protective member burn) if an adhesive tape (protective member) is attached to the front surface 101 of the workpiece 100.

[0051] Next, the inventors of the present invention confirmed the effects of the method for processing a workpiece according to embodiment 1. Fig. 8 is a diagram for explaining the effects of the method for processing a workpiece according to embodiment 1. Fig. 8 summarizes the results obtained when the effects were confirmed.

[0052] The right column of "Comparative Example" in Figure 8 shows a schematic diagram of the processing debris (polishing debris) adhering to the back surface of the workpiece, which is the surface to be polished, when a conventional grinding method for a workpiece is performed, in which only the workpiece is polished, without performing the retraction step 1002 of the workpiece processing method according to embodiment 1, in which the processing debris (polishing debris) is indicated by black dots. The right column of "Example" in Figure 8 shows a schematic diagram of the processing debris (polishing debris) adhering to the back surface of the workpiece, which is the surface to be polished, when the method for processing a workpiece according to embodiment 1, which includes the retraction step 1002, is performed, in which the processing debris (polishing debris) is indicated by black dots. Note that in both the "Comparative Example" and "Example" in Figure 8, a dry polishing process was performed using a polishing pad and no polishing liquid.

[0053] As shown in Fig. 8, the results showed that the amount of processing debris (polishing debris) adhering to the back surface, which is the surface to be polished, of the workpiece was significantly reduced when the method for processing a workpiece according to embodiment 1 including the retraction step 1002 was performed, compared to when a conventional grinding method for a workpiece was performed in which only polishing of the workpiece was performed without performing the retraction step 1002 of the method for processing a workpiece according to embodiment 1. This revealed that in the example shown in Fig. 8, by performing the retraction step 1002, it was possible to reduce the amount of processing debris (polishing debris) adhering to the back surface, which is the surface to be polished, of the workpiece after polishing.

[0054] Furthermore, Figure 8 shows a case where a dry polishing process was performed using a polishing pad without using a polishing liquid, but even when any other combination of polishing pads and polishing liquids was used, for example, polishing pads with or without fixed abrasive grains, polishing methods such as dry polishing without a polishing liquid or wet polishing with a polishing liquid were used, and polishing liquids such as slurry containing abrasive grains, pure water containing no abrasive grains, or alkaline polishing liquid were used, the results showed a similar tendency to the example shown in Figure 8, that is, when the retraction step 1002 was performed, the processing debris (polishing debris) adhering to the polished surface of the workpiece was significantly reduced.

[0055] The present invention is not limited to the above-described embodiments. In other words, various modifications can be made without departing from the gist of the present invention. In the first and second embodiments, the workpiece processing method is described as polishing the workpiece 100 with the polishing pad 26 disposed on one surface of the mount 21, which is a processing tool, in processing step 1001. However, the present invention is not limited to this. Alternatively, the workpiece processing method may be such that the workpiece 100 is ground with a grinding wheel disposed in a circular shape on one surface of a grinding tool, which is a processing tool, in the processing step. [Explanation of symbols]

[0056] 1 Processing equipment 10 Holding table 20 Processing Unit 21 Mount 26 Polishing pad (an example of a processing tool according to the present invention) 30 Table moving unit 40 Processing feed unit 50 Load Sensor 60 Control Unit 100 Workpiece

Claims

1. A method for processing a workpiece, comprising: a processing step in which a grinding or polishing tool is brought into contact with the workpiece held on the holding table and pressed against the workpiece; a retraction step in which, after the machining step is performed, the machining tool and the workpiece are moved relatively apart in a horizontal direction at a predetermined speed while the machining tool is in contact with the workpiece, thereby gradually reducing the contact area between the machining tool and the workpiece, and the workpiece on the holding table is moved away from the machining tool, after which machining is terminated; A method for processing a workpiece, comprising:

2. 2. The method for processing a workpiece according to claim 1, wherein the retraction step is performed while relatively adjusting the vertical distance between the holding table and the processing tool so that the load caused by the pressing force of the processing tool on the contact area becomes the desired load.

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