JP7724141B2 - Processing method of workpiece - Google Patents

Description

The present invention relates to a processing method for polishing a workpiece.

A polishing method for polishing a workpiece is known (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2005-166861

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

The present invention was made in consideration of these problems, and its purpose is to provide a processing method that can reduce the amount of processing debris that adheres to the polished surface of a workpiece after polishing the workpiece.

In order to solve the above-mentioned problems and achieve the object, the method for processing a workpiece of the present invention is a method for processing a workpiece, which comprises a processing step in which a grinding or polishing tool is brought into contact with the workpiece held on a holding table and processed while pressing, and a retraction step in which , after performing the processing step, while the processing tool is in contact with the workpiece, the processing tool and the workpiece are moved horizontally apart relatively at a predetermined speed, gradually reducing the contact area where the processing tool comes into contact with the workpiece , and the workpiece on the holding table is moved away from the processing tool, and then the processing is terminated .

The retraction step may be performed while adjusting the vertical distance between the holding table and the machining tool relative to one another so that the load exerted on the contact area by the pressing force of the machining tool becomes the desired load.

The present invention can reduce the amount of machining debris that adheres to the polished surface of a workpiece after it has been polished.

FIG. 1 is a perspective view showing an example of the configuration of a processing apparatus for carrying out a method for processing a workpiece according to a first embodiment. FIG. 2 is a cross-sectional view showing a main part of the processing apparatus of FIG. FIG. 3 is a flowchart showing an example of a processing procedure of the method for processing a workpiece according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the retracting step of FIG. FIG. 5 is a graph illustrating a method for processing a workpiece according to the second embodiment. FIG. 6 is a graph illustrating a method for processing a workpiece according to the second embodiment. 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. FIG. 8 is a diagram illustrating the effects of the method for processing a workpiece according to the first embodiment.

Modes for carrying out the present invention (embodiments) 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 would be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications to the configuration can be made without departing from the spirit of the present invention.

[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.

In embodiment 1, 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 planned division lines or devices formed on its surface 101. The workpiece 100 has a back surface 102 opposite the surface 101 as the surface to be polished (the surface to be polished), and a protective member for protecting the surface 101 may be attached to the back surface 101. Furthermore, the workpiece 100 is not limited to this in the present invention, and may also be a rectangular package substrate having multiple devices sealed with resin, a ceramic plate, a glass plate, or the like.

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

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

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

Furthermore, the holding table 10 is provided with a tilt adjustment unit 15 below it that 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 to adjust the tilt of the holding surface 13 of the holding table 10. In embodiment 1, the tilt adjustment units 15 are arranged in multiple locations (e.g., three locations) at equal intervals (e.g., 120-degree intervals) around the circumference. The tilt adjustment unit 15 is, for example, composed of an electric cylinder or air cylinder in which the rod can move in the Z-axis direction from within the cylinder, but the present invention is not limited to this and may also be composed of, for example, a piezoelectric element that expands and contracts in the Z-axis direction.

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 includes 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.

The polishing pad 26 is an example of a machining tool according to the present invention. The mount 21 is disc-shaped, with the polishing pad 26 for polishing the workpiece 100 disposed on one surface. The spindle 22 is cylindrical, with the mount 21 fixed to its lower end, and the polishing pad 26 attached to its underside. The spindle 22 rotates around an axis parallel to the vertical Z-axis direction. The mount 21 attached to the lower end of the spindle 22 is rotated around an axis parallel to the Z-axis direction by the spindle 22, causing the polishing pad 26 to come into contact with and press 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 interior of the mount 21 to the interior of the spindle 22.

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 fixed abrasive grains. In the first embodiment, the processing unit 20 may polish the rear 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; may polish the rear surface 102 of the workpiece 100 using the polishing pad 26 containing fixed abrasive grains while supplying pure water as the polishing liquid from the polishing liquid supply source 25; may perform chemical mechanical polishing (CMP) using the polishing pad 26 while supplying an alkaline polishing liquid from the polishing liquid supply source 25; or may perform dry polishing of the rear surface 102 of the workpiece 100 using the polishing pad 26 without supplying a polishing liquid from the polishing liquid supply source 25.

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 pass through. The spindle housing 23 supports the spindle 22 so that it can rotate around 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 movable in the Z-axis direction, which is the processing feed direction (polishing feed direction), via the holder 24 by the processing feed unit 40.

The table movement unit 30 is provided below the holding table 10, extending 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 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 toward or away from the workpiece 100 held on the holding table 10 in the vertical direction at a predetermined speed relative to the workpiece 100. Note that this vertical direction also includes the direction perpendicular to the holding surface 13 of the holding table 10.

The table movement unit 30 and the processing feed unit 40 each include a well-known ball screw rotatable 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 processing unit 20 so that it can move freely in the Y-axis or Z-axis direction. The table movement unit 30 and the processing feed unit 40 each also include a well-known position detector that detects the position of the holding table 10 or 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.

As shown in Figures 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 multiple locations (e.g., three locations) at equal intervals (e.g., 120-degree intervals) around the circumference 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 multiple locations (e.g., three locations) at equal intervals (e.g., 120-degree intervals) around the circumference of the holder 24. The table load sensor 51 and holder load sensor 52 measure the load 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 unit 40, and output the measured load value (actual measurement value) to the control unit 60. The table load sensor 51 and holder load sensor 52 are composed of, for example, 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.

The control unit 60 controls the operation of each component of the processing device 1, causing the processing device 1 to perform a polishing process using the processing unit 20, including the workpiece processing method according to embodiment 1. Based on the position of the holding table 10 in the Y-axis direction obtained from the table movement 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, 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.

Based on the Z-axis position of the processing unit 20 obtained from the processing feed unit 40, the control unit 60 calculates the relative vertical positional relationship (vertical distance) 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 vertical relative relationship 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 processing step 1001 (described below) is performed, the underside 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 underside of the polishing pad 26 and the back surface 102 of the workpiece 100 does not change. Instead, the polishing pad 26 distorts due to its elasticity, and is pressed into the workpiece 100, changing the load.

Based on the polishing processing conditions input by the operator from the input unit, the control unit 60 calculates the Z-axis position of the processing unit 20 when the load exerted by the pressure of the polishing pad 26 attached to the mount 21 on the contact area between the polishing pad 26 and the back surface 102 of the workpiece 100 when the polishing pad 26 is used to polish the back surface 102 of the workpiece 100 becomes the desired load. Note that, since the polishing processing conditions change the temperature of the space where polishing is performed, the state of the mount 21, the polishing liquid, the thickness of the workpiece 100, and other factors, the control unit 60 takes these factors into account when calculating the Z-axis position of the processing unit 20.

In embodiment 1, 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 ROM (Read Only Memory) or 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 processing device 1 to each component of the processing device 1 via the input/output interface device of the control unit 60.

The processing device 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 holding multiple 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.

The processing device 1 further includes a display unit (not shown). The display unit (not shown) is mounted on a cover (not shown) of the processing device 1 with its display surface facing outward, and displays a screen for setting the processing conditions of the processing device 1, a screen showing the processing results, and other screens that can be viewed by the operator. The display unit is configured with a liquid crystal display device or the like. The display unit is also 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.

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 processing apparatus 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 retraction step 1002 in FIG. 3. As shown in FIG. 3, the workpiece processing method according to embodiment 1 comprises processing step 1001 and retraction step 1002.

Processing step 1001 is a step in which 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.

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 (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 of the workpiece 100 before polishing is suction-held on the holding surface 13 of the holding table 10.

In 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. The polishing pad 26 attached to the mount 21 is then brought into contact with and pressed against the workpiece 100 on the holding table 10 by the processing feed unit 40, thereby polishing the back surface 102 of the workpiece 100 with the polishing pad 26.

In processing step 1001, the control unit 60 uses the processing feed unit 40 to position the processing unit 20 in the Z-axis direction calculated based on the polishing processing conditions and load setting values previously input by the operator via 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 Z-axis position of the processing unit 20 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.

In the retraction step 1002, 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.

Here, the predetermined speed may be any speed that is sufficiently faster than a speed that is so slow that it significantly reduces the efficiency of the polishing process, but is also sufficiently slower than a speed that is so fast that it generates significant frictional heat between the polishing pad 26 attached to the mount 21 and the back surface 102 (the surface to be polished) of the workpiece 100, or that it has a significant adverse effect on the quality of the polishing process. 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.

In the retraction step 1002, as shown in FIG. 4, the control unit 60 continues from the processing step 1001 by controlling the rotation 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 causes the table movement unit 30 to move the holding table 10 along the Y-axis direction in a direction away from the polishing pad 26 (the retraction direction). In the retraction 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.

In the retraction step 1002, after the control unit 60 has completely or a predetermined distance removed (retracted) the workpiece 100 on the holding table 10 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 movement unit 30, causes the processing feed unit 40 to further raise the polishing pad 26 vertically to prevent interference when the workpiece 100 is removed from the holding table 10, and stops the rotation of the holding table 10 and the workpiece 100 on the holding table 10 by the rotary drive source, thereby completing the polishing process by the processing unit 20.

The workpiece processing method according to embodiment 1, which has the above-described configuration, performs retraction step 1002, thereby positioning polishing pad 26 above workpiece 100 even after processing step 1001 is completed, thereby reducing the possibility of adhering processing debris (polishing debris) falling onto and adhering to back surface 102, the surface to be polished, of workpiece 100. Furthermore, since polishing pad 26 moves relatively toward the periphery of workpiece 100 while rubbing the surface to be polished of workpiece 100 as it moves away from workpiece 100, processing debris (polishing debris) adhering to the surface to be polished can be removed. Therefore, regardless of the polishing pad 26 or polishing liquid used for polishing, even when polishing workpiece 100 using a dry polishing pad 26 without polishing liquid, which is prone to adhesion of processing debris (polishing debris) in conventional methods, the effect of reducing processing debris (polishing debris) adhering to back surface 102, the surface to be polished, of workpiece 100 after polishing is achieved.

[Embodiment 2]
A method for machining 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 machining 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 machining 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.

Figure 5 is a graph showing the retraction step 1002 of embodiment 1. The dashed line 201 indicates how the load measured by the load sensor 50 is 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 Figure 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 increases as the area of the contact region decreases. Here, the area of the contact region on the horizontal axis of Figure 5 is expressed as a relative ratio, with the area of the contact region during processing step 1001 being set to 100%. Note that the solid line 202 in Figure 5 is an example of the correlation between the area of the contact region and the measured load, and varies slightly depending on the polishing processing conditions, etc.

In other words, if the load sensor 50 is controlled to maintain a constant measurement value during the retraction step 1002, as in the normal processing step 1001, the contact area of the polishing pad 26 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, surface burning or tape burning (protective member burning), which would burn the polished surface of the workpiece 100, may not occur, and in such cases, embodiment 1 will pose no problem.

Figure 6 is a graph showing embodiment 2 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, remains 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 force pressing against the workpiece 100 so that the load measurement value measured by the load sensor 50 gradually decreases.

In this way, the retraction 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 increase the distance so that the load measured by the load sensor 50 decreases in accordance with the decrease in the area of the contact area. For example, in the retraction 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 increase the distance when the load acting on the contact area exceeds a predetermined threshold, thereby controlling the load acting on the contact area to be equal to or less than the threshold.

Furthermore, in the retraction 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 is a desired constant load from the time when processing step 1001 is performed until the completion of retraction step 1002. For example, the retraction step 1002 according to the second embodiment can be performed by the control unit 60 of the processing apparatus 1 by controlling the load applied by the processing feed unit 40 to press the polishing pad 26 so that the load measurement value measured by the load sensor 50 gradually decreases from the time when processing step 1001 is performed and the area of the contact area becomes approximately zero at the time the load measurement value becomes approximately zero.

In embodiment 2, the memory unit of the control unit 60 of the processing device 1 stores the evacuation step control data 210 shown in FIG. 7, which is the processing condition for the evacuation step 1002. As shown in FIG. 7, the evacuation step control data 210 is data that compares the Y-axis position of the holding table 10 and the Z-axis position of the processing unit 20 with each other so that the load on the contact area is constant for each elapsed time since the start of the evacuation step 1002.

In the retraction step 1002 according to the second embodiment, the control unit 60 of the processing apparatus 1 references the retraction step control data 210 shown in FIG. 7 and controls the table movement unit 30 to control the position of the processing unit 20 in the Z-axis direction using the processing feed unit 40 in accordance with the 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 and controlling the load caused by the pressure of the polishing pad 26. This allows the load applied to the contact region during the retraction step 1002 to be controlled to the desired load.

The retraction step control data 210 is generated, for example, as follows. First, the area of the contact region, which changes as the machining unit 20 moves in the Y-axis direction, is calculated, and the optimal load sensor 50 measurement value is determined according to 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 load sensor 50 measurement value. In the retraction step 1002, the Z-axis position is adjusted as needed during machining so that the optimal load sensor 50 measurement value is obtained according to the machining unit 20's position 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.

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.

The workpiece processing method of embodiment 2 having the above configuration, in addition to the functions of embodiment 1, further performs the retraction step 1002 by adjusting the vertical distance between the holding table 10 and the polishing pad 26 using the control unit 60 of the processing apparatus 1 so that the load caused by the pressure of the polishing pad 26 on the contact area becomes the desired load. Therefore, in addition to the same effects as embodiment 1, the workpiece processing method of embodiment 2 can also reduce the risk of the load pressing the polishing pad 26 against the back surface 102 of the workpiece 100 increasing and becoming excessive. This prevents surface burns on the back surface 102 of the workpiece 100, which may occur if the load becomes excessive, and prevents tape burns (protective material burns) if adhesive tape (protective material) is attached to the front surface 101 of the workpiece 100.

Next, the inventors of the present invention confirmed the effects of the method for processing a workpiece according to embodiment 1. Figure 8 is a diagram illustrating the effects of the method for processing a workpiece according to embodiment 1. Figure 8 summarizes the results obtained when confirming the effects.

The column to the right of "Comparative Example" in Figure 8 shows a schematic diagram of the processing debris (polishing debris) adhering to the back surface (the surface to be polished) of a workpiece 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. The column to the right of "Example" in Figure 8 shows a schematic diagram of the processing debris (polishing debris) adhering to the back surface (the surface to be polished) of a workpiece when the method for processing a workpiece according to embodiment 1, which includes the retraction step 1002, is performed. 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.

As shown in Figure 8, when compared to a conventional workpiece grinding method in which only the workpiece is polished without performing the retraction step 1002 of the workpiece processing method according to embodiment 1, the method for processing a workpiece according to embodiment 1, which includes the retraction step 1002, results showed that the amount of processing debris (polishing debris) adhering to the back surface, which is the surface to be polished, was significantly reduced. This demonstrates that, in the example shown in Figure 8, performing the retraction step 1002 makes it 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.

Although Figure 8 shows a dry polishing process using a polishing pad and no polishing liquid, other combinations of polishing pads and polishing liquids were used, such as polishing pads with or without fixed abrasives, polishing methods such as dry polishing without polishing liquid or wet polishing with polishing liquid, and polishing liquids such as abrasive-containing slurry, pure water without abrasives, or alkaline polishing liquid. Even when performing the same comparative examples and examples as those shown in Figure 8, results were obtained showing a similar tendency to the example shown in Figure 8, in that the amount of processing debris (polishing debris) adhering to the polished surface of the workpiece was significantly reduced when the retraction step 1002 was performed.

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 exemplified by polishing the workpiece 100 with a polishing pad 26 arranged 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 in a processing step using a grinding wheel arranged in a ring shape on one surface of a grinding tool, which is a processing tool.

1 Processing device 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 (2)

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: The method for machining a workpiece according to claim 1, characterized in that the retraction step is performed while relatively adjusting the vertical distance between the holding table and the machining tool so that the load caused by the pressure of the machining tool on the contact area becomes the desired load.