Grinding apparatus and grinding method

Abstract

To realize efficient grinding work by suppressing consumption of a grinding wheel.SOLUTION: A grinder (1) includes an irradiator (22) that irradiates a workpiece (Q) with light having wavelengths equal to or shorter than that of 385nm, and a grinding machine (15) that grinds the workpiece irradiated with the light by the irradiator.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a grinding apparatus and a grinding method for grinding a workpiece. [Background technology]

[0002] In the manufacture of semiconductor devices, improving processability is an issue when grinding or polishing workpieces that have high hardness and chemical stability.

[0003] Patent Document 1 proposes a method for dry polishing a workpiece, in which a processing member made of a light-transmitting metal oxide is brought into contact with the workpiece, ozone gas containing water or an alkaline solution is supplied to the contact site, and ultraviolet light is irradiated onto the workpiece from the side of the processing member opposite to the side that contacts the workpiece. This processing method improves the polishing efficiency by utilizing a chemical reaction in which the processing surface of the workpiece is oxidized by irradiation with ultraviolet light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-131301 Summary of the Invention [Problem to be solved by the invention]

[0005] In a grinding device that grinds a workpiece by contacting a grinding wheel, there is a problem that the grinding wheel wears out rapidly when the workpiece is made of a hard-to-grind material that is high in hardness and has a high grinding load. The processing method in Patent Document 1 is applied to polishing a workpiece, and since the device configuration and processing content are different from grinding, there is a need for improved processability that is optimized for grinding.

[0006] An object of the present invention is to provide a grinding device and a grinding method that can suppress wear of the grinding wheel and achieve efficient grinding processing. [Means for solving the problem]

[0007] One aspect of the present invention is a grinding device comprising an irradiation unit that irradiates a workpiece with light having a wavelength of 385 nm or less, and a grinding unit that grinds the workpiece irradiated with the light by the irradiation unit.

[0008] In one embodiment, the grinding unit has a grinding wheel fixed to an annular base, and the irradiation unit is disposed on the inner periphery of the annular base.

[0009] It is preferable that the grinding unit is positioned opposite the workpiece so that a portion of the grinding surface of the workpiece is exposed, and that the irradiation unit irradiates the light onto the grinding surface in the area exposed from the grinding unit.

[0010] The irradiation unit is preferably disposed so as to extend in the radial direction of the workpiece.

[0011] A liquid supply unit may be provided that supplies liquid to the area of ​​the workpiece that is irradiated with the light.

[0012] One aspect of the present invention is a grinding method comprising the steps of irradiating a workpiece with light having a wavelength of 385 nm or less, and grinding an area of ​​the grinding surface of the workpiece that has been modified by irradiating the light. [Effects of the Invention]

[0013] According to the grinding device and grinding method of the above aspect, wear of the grinding wheel can be suppressed and efficient grinding processing can be achieved. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 3 is a side view showing the stage of air cutting in the grinding device of the first embodiment. [Figure 2] 3 is a side view showing an irradiation step and a grinding step in the grinding device of the first embodiment. FIG. [Figure 3]FIG. 2 is a plan view showing the arrangement of irradiation units in the grinding device of the first embodiment. [Figure 4] FIG. 10 is a side view showing an irradiation step and a grinding step in the grinding device of the second embodiment. [Figure 5] FIG. 10 is a plan view showing the arrangement of irradiation units in a grinding device according to a second embodiment. [Figure 6] FIG. 10 is a plan view showing the arrangement of irradiation units in a modified example of the second embodiment. [Figure 7] FIG. 1 is a side view showing a grinding apparatus equipped with a liquid supply unit. [Figure 8] FIG. 1 is a side view showing a grinding apparatus equipped with a liquid supply unit. [Figure 9] FIG. 1 is a side view showing a grinding apparatus equipped with a liquid supply unit. [Figure 10] FIG. 10 is a perspective view showing a grinding device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The grinding apparatus in each of the following embodiments performs grinding on a workpiece Q such as a disk-shaped wafer. The Z-axis direction is the vertical direction of the grinding apparatus, with the +Z direction side being the top and the -Z direction side being the bottom. The grinding apparatus in each of the embodiments is controlled by a control unit (not shown) to automatically perform grinding processing on the workpiece Q. The control unit is equipped with a processor and memory, and the processor performs processing according to a program stored in the memory to control each part of the grinding apparatus. The operation of the grinding apparatus described below is performed under the control of the control unit.

[0016] The grinding machine 1 of the first embodiment shown in FIGS. 1 to 3 includes a holding table 10. The upper surface of the holding table 10 is a holding surface 11 capable of holding a workpiece Q. Air is sucked in using a suction mechanism 12 connected to a suction path within the holding table 10, creating a negative pressure on the holding surface 11 to suction-hold the workpiece Q. The holding surface 11 is a conical surface with a slight inclination that is imperceptible to the naked eye. The angle of the holding table 10 is set so that a predetermined radial line extending from the center of the holding surface 11 to the periphery is horizontal. The holding table 10 is rotated about an axis passing through the center of the holding surface 11 by a table rotation mechanism 13 equipped with a drive source such as a motor. A protective member P is attached to the surface (lower surface) of the workpiece Q that is placed on the holding surface 11, and the workpiece Q is held on the holding surface 11 via the protective member P.

[0017] The holding table 10 can change the angle of the holding surface 11 with respect to the Z-axis direction by a table tilt adjustment mechanism (not shown). The table tilt adjustment mechanism supports the support unit of the holding table 10, including the table rotation mechanism 13, at three or more fulcrums, and can change the relative height positions of these fulcrums to change the tilt direction and angle of the holding table 10. The table tilt adjustment mechanism is configured to be able to change the height positions of at least two fulcrums using a motor-driven feed screw unit or the like.

[0018] A grinding unit 15 is disposed above the holding table 10. The grinding unit 15 includes a disk-shaped mounter 17 at the lower end of a spindle 16, which is a rotation axis extending in the Z-axis direction, and an annular base 18 is attached to the underside of the mounter 17. In this embodiment, the portion including the mounter 17 and the annular base 18 is referred to as a grinding wheel W. The annular base 18 is an annular member disposed on the periphery of the mounter 17 and has the cross-sectional shape shown in FIG. 7. A plurality of grinding wheels 19 are disposed in an annular shape on the underside of the annular base 18. Note that while FIG. 3 depicts the arrangement of the grinding wheels 19 as an annular shape, in reality, a plurality of grinding wheels 19 are arranged at predetermined intervals around the annular base 18 within this annular arrangement.

[0019] The spindle 16 is rotated about an axis in the Z-axis direction by a spindle rotation mechanism 20. The spindle rotation mechanism 20 includes a bearing that rotatably supports the spindle 16, and a spindle motor that applies a driving force to rotate the spindle 16. When the spindle 16 is rotated by the spindle rotation mechanism 20, the grinding wheel W rotates, and the multiple grinding stones 19 move in the rotational direction in accordance with the rotation of the grinding wheel W. The grinding unit 15 is moved in the Z-axis direction by an elevator mechanism 21. The elevator mechanism 21 is composed of a ball screw unit including a ball screw and a motor, an air cylinder unit, etc.

[0020] When grinding the workpiece Q using the grinding device 1, the workpiece Q is transported to the position of the holding table 10 and held on the holding surface 11 via the protective member P. The suction mechanism 12 is operated to place the holding surface 11 in a state in which it holds the workpiece Q by suction. The table rotation mechanism 13 is operated to rotate the holding table 10 holding the workpiece Q. In the grinding unit 15, the spindle rotation mechanism 20 is operated to rotate the spindle 16, and the lifting mechanism 21 is operated to lower the grinding unit 15. These operations cause the grinding wheel 19 and the workpiece Q to rotate relatively, and the grinding wheel 19 comes into contact with the grinding surface Qa, which is the upper surface of the workpiece Q, to grind the workpiece Q. During grinding, the holding table 10 rotates in the rotation direction Ra shown by the arrow in FIG. 3, and the grinding wheel W and the grinding stone 19 on its underside rotate in the rotation direction Rb shown by the arrow in FIG.

[0021] As shown in FIG. 3, during grinding, the relative positions of the holding table 10 and the grinding unit 15 are set so that the grinding wheel 19 passes through the center C of the holding table 10 in a plan view. The bottom surface of the grinding wheel 19 contacts and grinds the grinding surface Qa of the workpiece Q in an arc-shaped grinding region Ea, one end of which is the center C of the holding table 10. The grinding wheel 19 grinds the workpiece Q by moving in the rotation direction Rb from a contact start position D on the outer periphery of the workpiece Q toward the center C. Because the workpiece Q is held in a shape that conforms to the conical holding surface 11, the grinding wheel 19 moving in the rotation direction Rb contacts the workpiece Q in the grinding region Ea from the contact start position D to the center C, but the workpiece Q is separated from the bottom surface of the grinding wheel 19 in the non-grinding region Eb beyond. The workpiece Q held on the holding table 10 rotates in the rotation direction Ra as the holding table 10 rotates, so that the circumferential position of the workpiece Q relative to the grinding area Ea changes continuously, and by rotating the holding table 10 one or more times, the entire circumferential direction of the workpiece Q can be brought into sequential contact with the grinding wheel 19. In this way, the entire grinding surface Qa of the workpiece Q is ground by contact with the grinding wheel 19.

[0022] In recent years, there has been an increasing demand for so-called wide-gap semiconductors, which have wide bandgaps and are made from materials such as SiC (silicon carbide) and GaN (gallium nitride). When the workpiece Q is made of a hard, difficult-to-grind material such as SiC or GaN, grinding the workpiece Q without any processing presents a problem of wear on the grinding wheel 19. For example, to grind a workpiece Q made of a hard-to-grind material to a thickness of 1 μm, the grinding wheel 19 is removed by approximately 2 μm in the thickness direction. Furthermore, grinding a workpiece Q made of a hard-to-grind material requires a long time. Therefore, there is a need to efficiently grind even hard workpieces Q while minimizing wear on the grinding wheel 19. The type of workpiece Q to be ground is not limited to semiconductor wafers made of SiC or GaN, but may also be wafers of other hard materials.

[0023] The grinding apparatus 1 of this embodiment includes an irradiation unit 22 that irradiates light onto the workpiece Q held on the holding table 10. The irradiation unit 22 is positioned above the workpiece Q on the holding table 10 and irradiates light downward. The light irradiated by the irradiation unit 22 has a wavelength of 385 nm or less. That is, the irradiation unit 22 irradiates ultraviolet light or light (electromagnetic waves) with a wavelength shorter than ultraviolet light. The range of light shorter than ultraviolet light may include X-rays and gamma rays. The workpiece Q has the ability to absorb such short-wavelength light. When the irradiation unit 22 irradiates the workpiece Q with the light, the workpiece Q is excited. A photochemical reaction occurs on the grinding surface Qa, causing oxidation in an oxygen-containing atmosphere. This results in the formation of an oxide film on the grinding surface Qa, resulting in surface modification. This oxide film is less hard than the original workpiece Q, making grinding relatively easy, thereby reducing the grinding load when grinding the grinding surface Qa. As a result, wear of the grinding wheel 19 is reduced, and it becomes possible to grind the grinding surface Qa in a shorter time than before.

[0024] 3, the irradiation unit 22 is disposed in a position different from the grinding area Ea directly below the grinding wheel 19 in the rotation direction of the holding table 10. Then, when the grinding surface Qa is ground by the grinding wheel 19, the irradiation unit 22 continuously irradiates the grinding surface Qa with light at a position different from the grinding area Ea. As a result, a cycle including a step of irradiating the workpiece Q with light having a wavelength of 385 nm or less to modify the grinding surface Qa (modification step), a step of grinding the area of ​​the grinding surface Qa modified by irradiating it with light (grinding step), and a step of modifying the unmodified grinding surface Qa exposed by grinding by irradiating it with light (modification step) is automatically and continuously repeated, so that the grinding surface Qa is always ground in a modified state in the grinding area Ea. Therefore, grinding can be continuously performed with a reduced grinding load on the workpiece Q until the workpiece Q reaches the desired thickness, thereby improving the processing efficiency of the workpiece Q while suppressing wear on the grinding wheel 19. The above cycle is realized simply by supplementing the irradiation of light from the irradiation unit 22 at a position different from the grinding wheel 19, without changing the general grinding operation of pressing the grinding wheel 19 against the workpiece Q and rotating the workpiece Q and the grinding wheel 19 relative to each other. Therefore, the operational control of the grinding unit 15 during grinding is not complicated, and there is no need to ensure a standby time for irradiating the workpiece Q with light.

[0025] The grinding unit 15 is disposed opposite the workpiece Q so that a portion of the grinding surface Qa is exposed. Specifically, as shown in Fig. 2, when the grinding unit 15 grinds the workpiece Q, the portions of the grinding unit 15 other than the grinding wheel 19 do not come into contact with the grinding surface Qa, exposing the grinding surface Qa. For example, the mounter 17 and a portion of the annular base 18 of the grinding wheel W face the grinding surface Qa, but there is a gap in the Z-axis direction between the lower surface of the mounter 17 or the lower surface of the annular base 18 and the grinding surface Qa, so that the grinding surface Qa is exposed. 3, the grinding unit 15 is disposed so that the grinding wheel 19 passes through the center C of the holding table 10 in a plan view, and therefore in the radially outer region of the mounter 17 and the annular base 18 (the region to the left of the mounter 17 and the annular base 18 in FIG. 3), the grinding unit 15 including the grinding wheel 19 is not disposed above the grinding surface Qa, and the grinding surface Qa is widely exposed. The irradiation unit 22 then irradiates the region of the grinding surface Qa that is exposed from the grinding unit 15 with light for surface modification.

[0026] By irradiating light from the irradiation unit 22 toward the exposed area of ​​the grinding surface Qa of the workpiece Q that is not covered by the grinding unit 15 or the like, oxidation is promoted using oxygen contained in the air surrounding the grinding surface Qa, and the grinding surface Qa can be efficiently modified. Furthermore, since a processing unit such as a grinding unit is not disposed immediately above the workpiece Q and the grinding surface Qa of the workpiece Q is exposed, the irradiation unit 22 can be disposed in a position close to the grinding surface Qa, and the light emitted from the irradiation unit 22 can be efficiently irradiated onto the grinding surface Qa.

[0027] In the grinding apparatus 1, the grinding surface Qa is contacted by a circularly arranged grinding wheel 19, and the grinding surface Qa is exposed in areas other than the grinding wheel 19. In other words, the grinding apparatus 1 of this embodiment differs from polishing apparatuses in which a processing member such as a polishing pad is placed in close contact with the workpiece over a wide area. For example, the processing method described in Patent Document 1, which is intended for polishing a workpiece, irradiates the workpiece surface with ultraviolet light passing through the processing member while the processing member is in close contact with the workpiece surface over a wide area. This presents problems such as difficulty in promoting oxidation of the workpiece surface and difficulty in efficiently irradiating the workpiece surface with ultraviolet light. The inventors of the present application focused on the unique configuration of grinding apparatuses, which differ from polishing apparatuses, and discovered that by positioning the irradiation unit 22 facing the grinding surface Qa without overlapping with the grinding wheel 19, the grinding surface Qa can be efficiently modified with a simple configuration.

[0028] In the grinding device 1 of the first embodiment shown in FIGS. 1 to 3, an irradiation unit 22 is disposed in a region radially outward of the grinding wheel W. The irradiation unit 22 is configured by arranging a plurality of light sources 23 in a linear manner, and can irradiate a linear region downward with light. The arrangement direction of the plurality of light sources 23 is the longitudinal direction of the irradiation unit 22. For example, each light source 23 is an ultraviolet light-emitting diode (LED) that emits light with a center wavelength of 385 nm or less. Note that the configuration of the irradiation unit 22 is not limited to the above example, and a tubular excimer lamp having a cylindrical light irradiation surface may also be used as the light source 23.

[0029] The irradiation unit 22 is disposed to extend in the radial direction of the workpiece Q. The longitudinal length of the irradiation unit 22 is equal to the radius of the workpiece Q. As shown in FIG. 3 , in a plan view, one longitudinal end of the irradiation unit 22 is located near the center C of the holding table 10, and the other longitudinal end is located near the outer edge of the workpiece Q. When the holding table 10 is rotated by the table rotation mechanism 13, the workpiece Q held on the holding table 10 moves in the rotational direction below the irradiation unit 22. The relative rotation between the workpiece Q and the irradiation unit 22 allows the light from the irradiation unit 22 to irradiate the entire circumferential area of ​​the grinding surface Qa. In other words, by using the irradiation unit 22 extending in the radial direction of the workpiece Q and moving the irradiation unit 22 relative to the holding table 10 as the holding table 10 rotates, it is possible to modify substantially the entire grinding surface Qa even if the irradiation unit 22 does not cover the entire grinding surface Qa.

[0030] The center of the workpiece Q is included in the grinding area Ea with which the grinding wheel 19 contacts during grinding, and is therefore always in contact with the grinding wheel 19. Therefore, if the irradiation unit 22 is positioned directly above the center of the workpiece Q, there is a possibility that the grinding wheel 19 will interfere with the irradiation unit 22. For this reason, in the arrangement of the irradiation unit 22 shown in FIG. 3, one longitudinal end of the irradiation unit 22 is set at a position slightly shifted radially outward from the center C of the holding table 10 to prevent interference between the grinding wheel 19 and the irradiation unit 22. With this arrangement, the light irradiated from the irradiation unit 22 may not reach the central region of the workpiece Q. However, most of the workpiece Q excluding the central region is included in the target area for surface modification of the ground surface Qa by irradiation with light from the irradiation unit 22, and therefore a sufficient effect of improving processability during grinding can be obtained. Furthermore, since the central region of the workpiece Q is always in contact with the grinding wheel 19 during grinding, the grinding rate is higher and grinding progresses more easily than in other regions, so even if modification is not performed by irradiating light from the irradiation section 22, a balance in grinding efficiency can be maintained between the central region and the surrounding modified regions.

[0031] As shown in FIGS. 1 and 2, the irradiation unit 22 is supported by an irradiation unit support mechanism 24. The irradiation unit support mechanism 24 has a support arm 26 extending horizontally from a base 25 supported on a base (not shown) of the grinding apparatus 1, and the irradiation unit 22 is attached to the lower end of the support arm 26. The irradiation unit support mechanism 24 includes a horizontal movement mechanism 27 that moves the support arm 26 horizontally relative to the base 25, and an elevating mechanism 28 that moves the support arm 26 up and down (in the Z-axis direction) relative to the base 25. The horizontal movement mechanism 27 can change the position of the irradiation unit 22 at least in the radial direction of the workpiece Q and is configured as a linear movement mechanism that moves the irradiation unit 22 linearly in the horizontal direction. Detailed structures of the horizontal movement mechanism 27 and the elevating mechanism 28 are not shown, but for example, a well-known ball screw unit including a ball screw and a motor, or an air cylinder unit can be used.

[0032] The position of the irradiation unit 22 in the Z-axis direction is controlled by the lifting mechanism 28, and light is irradiated from the irradiation unit 22 toward the grinding surface Qa while maintaining a predetermined distance between the irradiation unit 22 and the grinding surface Qa. The distance between the irradiation unit 22 and the grinding surface Qa is preferably set to approximately 1 mm to 20 mm. This setting ensures that the light emitted by the irradiation unit 22 reaches the grinding surface Qa directly below, and promotes oxidation of the grinding surface Qa by oxygen in the air between the irradiation unit 22 and the grinding surface Qa, thereby efficiently modifying the grinding surface Qa.

[0033] During a loading operation in which the workpiece Q before grinding is placed on the holding surface 11 of the holding table 10, or during a carrying-out operation in which the workpiece Q after grinding is carried out from the holding table 10, the horizontal movement mechanism 27 may be operated to move the irradiation unit 22 to a retracted position on the radially outer side of the holding table 10 (a position where the irradiation unit 22 and the holding surface 11 do not face each other in the Z-axis direction). This allows the workpiece Q to be carried in and out without being obstructed by the irradiation unit 22.

[0034] FIG. 1 shows the air-cutting stage in the grinding apparatus 1. During the air-cutting stage, the lifting mechanism 21 is operating to lower the grinding unit 15 toward the workpiece Q, and the grinding wheel 19 is not in contact with the grinding surface Qa. The spindle rotation mechanism 20 has started to rotate the spindle 16, and the table rotation mechanism 13 has started to rotate the holding table 10. During the air-cutting stage, the horizontal movement mechanism 27 and the lifting mechanism 28 may be operated to move the irradiation unit 22 toward and close to the grinding surface Qa, and light irradiation from the irradiation unit 22 toward the grinding surface Qa may begin. In other words, the irradiation step may be performed first. As described above, the grinding surface Qa is modified by the irradiation of light from the irradiation unit 22, making it easier to grind. On the grinding surface Qa, the area that has been modified by irradiating it with light from the irradiation unit 22 maintains its modified state even after a certain amount of time has passed. Therefore, by starting to modify the grinding surface Qa from the air cutting stage, the next grinding step can be started quickly, improving time efficiency.

[0035] During the air cutting stage, the grinding wheel 19 does not yet overlap the central region of the workpiece Q, and there is space above the central region. Therefore, the horizontal movement mechanism 27 may be operated to move the irradiation unit 22 toward the center in the radial direction of the workpiece Q to modify the ground surface Qa in the central region of the workpiece Q. In this case, once the grinding unit 15 descends and approaches the workpiece Q to a predetermined distance or closer, the horizontal movement mechanism 27 may be operated to move the irradiation unit 22 slightly toward the outside in the radial direction of the workpiece Q to prevent interference between the grinding wheel 19 and the irradiation unit 22. Note that the holding table 10 may be equipped with a horizontal movement mechanism, and the holding table 10 may be moved relative to the irradiation unit 22 to change the irradiation range of light from the irradiation unit 22 onto the workpiece Q.

[0036] 2 shows the irradiation step and grinding step in the grinding apparatus 1. In the irradiation step, as described above, the workpiece Q is irradiated with light from the irradiation unit 22 to modify the grinding surface Qa. In the grinding step, as described above, the grinding wheel 19 is brought into contact with the grinding surface Qa in the grinding region Ea shown in FIG. 3, and the grinding surface Qa is ground by the grinding wheel 19 while the workpiece Q and the grinding wheel 19 are rotated relative to each other. The region of the grinding surface Qa that has been modified by irradiating it with light from the irradiation unit 22 moves to the grinding region Ea by the rotation of the holding table 10 and is ground, thereby reducing the grinding load and suppressing wear on the grinding wheel 19.

[0037] Because the light irradiation area in the irradiation step and the grinding area Ea in the grinding step are in different positions, the operation of the grinding device 1 can be performed by continuously rotating the holding table 10 and the spindle 16 while simultaneously irradiating light from the irradiation unit 22 and grinding with the grinding wheel 19, which is highly time-efficient. Note that when the area of ​​the grinding surface Qa that has been modified in the irradiation step moves with the rotation of the holding table 10 and reaches the grinding area Ea, it becomes the target for grinding in the grinding step and is ground. Therefore, when each area of ​​the grinding surface Qa of the workpiece Q is used as a reference, there is a time difference between the implementation of the irradiation step and the implementation of the grinding step, and a relationship is established in which the grinding step is performed after the irradiation step.

[0038] In the irradiation step, light from the irradiation unit 22 may be irradiated onto the central region of the workpiece Q, which is normally covered by the grinding wheel 19, to modify the ground surface Qa in the central region. Specifically, the grinding wheel W and the holding table 10 of the grinding unit 15 are moved relatively in the horizontal direction by the width of the grinding wheel 19 to expose the central region of the workpiece Q, and light is irradiated from the irradiation unit 22 toward the exposed central region. As a first mode for exposing the central region of the workpiece Q, when the grinding wheel W is movable in the horizontal direction and the holding table 10 is not movable in the horizontal direction, the grinding wheel W is moved to expose the central region of the workpiece Q, and the horizontal movement mechanism 27 is operated to move the irradiation unit 22 above the exposed portion, and light is irradiated from the irradiation unit 22. As a second form of exposing the central region of the workpiece Q, when the holding table 10 is movable horizontally and the grinding wheel W does not move horizontally, the position of the irradiation unit 22 is fixed, the holding table 10 is moved so that the central region of the workpiece Q is positioned below the irradiation unit 22, and light is irradiated from the irradiation unit 22.

[0039] In the grinding apparatus 2 of the second embodiment shown in FIGS. 4 and 5, an irradiation unit 29 is provided in the grinding unit 15. Similar to the irradiation unit 22 of the first embodiment, the irradiation unit 29 is configured by arranging a plurality of light sources 23 in a linear manner, and is capable of irradiating a linear area downward with light. The irradiation unit 29 is fixed to a desired location in the grinding unit 15 at a position on the underside of the grinding wheel W, and is disposed on the inner periphery of the grinding stone 19. The irradiation unit may also be fixed to a desired location in the grinding unit 15 at a position outside the grinding wheel W.

[0040] The irradiation section 29 of the grinding apparatus 2 of this embodiment has the same effect as the irradiation section 22 of the grinding apparatus 1 of the first embodiment described above, and a detailed description of the effect will be omitted. By attaching the irradiation section 29 to the grinding unit 15, there is an advantage that a dedicated support mechanism such as the irradiation section support mechanism 24 of the first embodiment is not required, and the structure is simplified.

[0041] In order to irradiate the grinding surface Qa evenly with light overall, the irradiation unit 29 is preferably fixed and extends in a direction from the center outward in the radial direction of the grinding wheel W, as shown in Fig. 5. In other words, in a plan view, the irradiation unit 29 preferably extends in a direction connecting the center C of the holding table 10 and the center of the grinding wheel W at a specific position (Fig. 5) in the rotation direction of the grinding wheel W. According to the configuration in Fig. 5, the amount of light irradiated from the irradiation unit 29 to the grinding surface Qa can be made uniform within the rotation range of the grinding wheel W in which the irradiation unit 29 faces the workpiece Q.

[0042] Note that even if the light is not evenly irradiated onto the grinding surface Qa and only a portion of the grinding surface Qa is modified, the grinding load is reduced, and a certain degree of effect can be obtained. From this perspective, the arrangement of the irradiation unit provided in the grinding unit 15 may be different from that shown in FIG. 5. For example, as in the modified example shown in FIG. 6, the irradiation unit 29 provided in the grinding unit 15 may extend in a direction that does not pass through the center of the grinding wheel W in a plan view. As shown in FIG. 6, the irradiation unit 29 extends in a direction outward from the center C of the holding table 10 at a specific position in the rotation direction of the grinding wheel W, and in this state, light can be irradiated onto a radial region of the workpiece Q.

[0043] This embodiment differs from the first embodiment in that, when the grinding wheel W is rotated, the irradiation unit 29 attached to the grinding unit 15 rotates along with the grinding wheel W, and the irradiation unit 29 does not face the workpiece Q within a certain range in the rotation direction of the grinding wheel W. However, when the workpiece Q is ground, the grinding wheel W and the workpiece Q rotate relatively to each other, and the range of the grinding surface Qa facing the grinding wheel W changes continuously, so that the light from the irradiation unit 29 can be irradiated onto the entire circumferential direction of the grinding surface Qa (excluding the central region of the grinding surface Qa with which the grinding stone 19 is always in contact).

[0044] As a method for efficiently irradiating the grinding surface Qa with light from the irradiation unit 29, the grinding unit 15 may be set to an irradiation position as shown in FIGS. 5 and 6 , where substantially the entire irradiation unit 29 faces the grinding surface Qa. At the irradiation position, the grinding wheel W may be temporarily stopped from rotating while the holding table 10 is rotated. The workpiece Q may be rotated one or more times below the fixed irradiation unit 29 to modify the grinding surface Qa. The grinding wheel W may then be rotated to grind the workpiece Q with the grinding wheel 19. That is, in the irradiation step, the grinding surface Qa can be efficiently modified by rotating the holding table 10 while the grinding unit 15 is maintained at the irradiation position without rotating the grinding wheel W. When the grinding unit 15 is held at the irradiation position, the grinding unit 15 may be moved upward in the Z-axis direction to move the grinding wheel 19 away from the grinding surface Qa. Subsequently, after the grinding surface Qa has been modified, in the grinding step, the grinding wheel W is rotated to bring the grinding stone 19 into contact with the grinding surface Qa to perform grinding.

[0045] As another method for efficiently irradiating the grinding surface Qa with light, an irradiation unit with a larger light-emitting area than the illustrated irradiation unit 29 may be mounted on the grinding unit 15 so that the irradiation unit always faces the grinding surface Qa regardless of changes in the position in the rotational direction of the grinding wheel W. For example, by attaching an irradiation unit with a wide light-emitting surface facing the grinding surface Qa (an irradiation unit whose light-emitting surface is a circular range on the inner periphery of the grinding wheel 19) via a separate member below the mounter 17, it is possible to efficiently irradiate the entire grinding surface Qa with light while grinding is being performed without temporarily stopping the rotation of the grinding wheel W.

[0046] 7 to 9 show the grinding apparatus 1 of the first embodiment, further including a liquid supply unit that supplies liquid to the area of ​​the workpiece Q that is irradiated with light from the irradiation unit 22. The liquid supplied from the liquid supply unit is, for example, pure water. When water is in contact with the grinding surface Qa, oxygen molecules in the water act as an oxidation source, making the grinding surface Qa more susceptible to oxidation than areas that are in contact with the air. Therefore, by supplying a liquid that has the property of promoting oxidation, such as water, to the area that is irradiated with light from the irradiation unit 22, the effect of modifying the grinding surface Qa can be improved.

[0047] The liquid supply unit 30 of the first example shown in FIG. 7 is configured to allow liquid delivered from a liquid supply source 31 to flow into an internal flow path 32 formed inside the grinding unit 15 and then supply the liquid from a supply port 33 provided on the underside of the annular base 18. The liquid supply source 31 includes a tank for storing liquid and a pump for delivering the liquid from the tank at a predetermined pressure. The internal flow path 32 includes a flow path extending vertically inside the spindle 16, a radial flow path connected to the lower end of the vertical flow path and extending radially inside the mounter 17, and multiple outlet flow paths extending downward from the radial flow path and vertically penetrating the annular base 18. The lower ends of the multiple outlet flow paths each constitute a supply port 33. That is, multiple supply ports 33 are formed on the underside of the annular base 18 at different positions circumferentially. Each supply port 33 is located on the inner periphery of the grinding wheel 19 and is disposed near the grinding wheel 19.

[0048] The liquid delivered from the liquid supply source 31 passes through the internal flow path 32 and flows downward from the supply port 33. During grinding, the spindle 16, the mounter 17, and the annular base 18 are rotated, so the liquid supplied from the supply port 33 to the inner periphery of the grinding wheel 19 tries to move toward the outer periphery due to centrifugal force, and flows toward the outer periphery of the grinding wheel 19 through the gap between the underside of the grinding wheel 19 and the grinding surface Qa and through the circumferential gaps set between the multiple grinding wheels 19. As a result, the liquid is supplied to the gap between the irradiation unit 22 arranged on the outer periphery of the grinding wheel 19 and the grinding surface Qa.

[0049] 8 has a structure in which liquid delivered from a liquid supply source 36 is supplied from a liquid supply nozzle 37 disposed on the inner periphery of the grinding wheel 19. The liquid supply unit 35 includes a tank for storing the liquid, a pump for delivering the liquid from the tank at a predetermined pressure, and the like. The liquid supply nozzle 37 includes a flow path extending from the center to the outer periphery in the radial direction of the annular base 18, and the tip of the flow path serves as a supply port 38. The supply port 38 is located opposite the inner periphery of the grinding wheel 19.

[0050] The liquid delivered from the liquid supply source 36 passes through a liquid supply nozzle 37 and is sprayed from a supply port 38 toward the vicinity of the processing point where the grinding wheel 19 is in contact with the grinding surface Qa, and flows to the outer periphery of the grinding wheel 19 through the gap between the lower surface of the grinding wheel 19 and the grinding surface Qa and through circumferential gaps set between the multiple grinding wheels 19. This allows the liquid to be supplied to the gap between the irradiation unit 22 arranged on the outer periphery of the grinding wheel 19 and the grinding surface Qa.

[0051] The liquid supply unit 40 of the third example shown in FIG. 9 is configured to allow liquid delivered from a liquid supply source 41 to flow into a flow path 42 connected to the irradiation unit 22 and supply the liquid to the underside of the irradiation unit 22. The liquid supply source 41 includes a tank for storing the liquid and a pump for delivering the liquid from the tank at a predetermined pressure. The liquid delivered from the liquid supply source 41 passes through the flow path 42 and is supplied to the gap between the irradiation unit 22 and the grinding surface Qa. Because the liquid is supplied directly to the underside of the irradiation unit 22, it is possible to easily and reliably modify the grinding surface Qa with a small amount of liquid.

[0052] As described above, in any of the liquid supply units 30, 35, and 40, liquid can be supplied to the gap between the irradiation unit 22 and the grinding surface Qa, thereby promoting the modification of the grinding surface Qa when light is irradiated from the irradiation unit 22. Because the liquid supply area is near the processing point (grinding area Ea) where the grinding wheel 19 contacts the grinding surface Qa, the liquid can be used as a grinding fluid supplied during grinding to cool the area near the processing point and remove processing debris. In other words, the grinding fluid supplied near the processing point can be used as a medium to promote the modification of the grinding surface Qa. In particular, the liquid supply unit 30 shown in FIG. 7 and the liquid supply unit 35 shown in FIG. 8 utilize a grinding fluid supply structure configured to supply grinding fluid to the area near the processing point as a target. This allows for efficient modification of the grinding surface Qa while utilizing the structure of a typical grinding machine.

[0053] 7 to 9 is a configuration in which a liquid supply unit is provided in the grinding apparatus 1 of the first embodiment, but a similar liquid supply unit may also be provided in the grinding apparatus 2 of the second embodiment (FIGS. 4 to 6). When applied to the grinding apparatus 2, by providing a liquid supply nozzle that sprays liquid from the outer periphery side toward the inner periphery side of the grinding wheel 19, opposite to the liquid supply nozzle 37 shown in FIG. 8, it becomes easier to supply liquid between the irradiation unit 29 provided on the inner periphery side of the grinding wheel 19 and the grinding surface Qa.

[0054] When grinding a workpiece to different surface roughnesses in stages using multiple types of grinding wheels with different abrasive grain sizes, finish grinding using a grinding wheel with finer abrasive grains is more difficult to perform than rough grinding using a grinding wheel with coarser abrasive grains, and the grinding load is more likely to increase. Therefore, the grinding apparatus and grinding method disclosed herein are particularly useful for finish grinding. Focusing on this point, FIG. 10 shows a grinding apparatus 3 according to a third embodiment as an example of application to a grinding apparatus equipped with multiple grinding units. The grinding apparatus 3 is controlled by a control unit (not shown) and performs a series of operations, such as transport, grinding, and cleaning, for the workpiece Q, fully automatically.

[0055] The first grinding unit 50 of the grinding device 3 is a grinding unit for rough grinding. The first grinding unit 50 has a grinding wheel formed by attaching an annular base 53 via a disk-shaped mounter 52 to the lower end of a spindle 51 extending in the Z-axis direction, and a plurality of grinding wheels 54 are arranged in an annular shape on the underside of the annular base 53. The spindle 51 is rotated by a motor provided in a spindle unit 55. The first grinding unit 50 is supported by an elevating mechanism 56 consisting of a ball screw unit so as to be movable up and down (in the Z-axis direction).

[0056] The second grinding unit 60 of the grinding device 3 is a grinding unit for finish grinding. The second grinding unit 60 has a grinding wheel formed by attaching an annular base 63 via a disk-shaped mounter 62 to the lower end of a spindle 61 extending in the Z-axis direction, and a plurality of grinding wheels 64 are arranged in an annular shape on the underside of the annular base 63. The abrasive grains contained in the grinding wheels 64 have a smaller grain size than the abrasive grains contained in the grinding wheel 54. The spindle 61 is rotated by a motor provided in the spindle unit 65. The second grinding unit 60 is supported by an elevator mechanism 66 consisting of a ball screw unit so as to be movable up and down (in the Z-axis direction).

[0057] Three holding tables 71 are supported on a turntable 70. Each holding table 71 has a structure similar to that of the holding table 10 in the grinding apparatus 1 of the first embodiment. A turntable rotation mechanism 72 equipped with a motor rotates the turntable 70 by 120°, thereby sequentially moving the three holding tables 71 to a first processing area, a second processing area, and a transfer area. The first processing area is an area where the workpiece Q held on the holding table 71 is roughly ground by the first grinding unit 50 and is located below the first grinding unit 50. The second processing area is an area where the workpiece Q held on the holding table 71 is finish ground by the second grinding unit 60 and is located below the second grinding unit 60. The transfer area is an area where the workpiece Q is transported to and from the holding table 71 by a first transport unit 73 and a second transport unit 74.

[0058] An irradiation section 75 is disposed near the second grinding unit 60. A support arm 77 extends horizontally from a base section 76 supported on a base 80 of the grinding apparatus 3, and the irradiation section 75 is supported at the tip end of the support arm 77. The irradiation section 75 has the same structure and function as the irradiation section 22 in the grinding apparatus 1 of the first embodiment described above. The support arm 77 can be moved horizontally (in the longitudinal direction of the irradiation section 75) relative to the base section 76 by a horizontal movement mechanism (not shown). The irradiation section 75 can be moved up and down (in the Z-axis direction) by an elevation mechanism 78 provided between the support arm 77 and the irradiation section 75.

[0059] The workpiece Q is stored in a cassette 81 and transported to the grinding device 3, and the cassette 81 is placed on a cassette stage 82. The workpiece Q before grinding is drawn out of the cassette 81 by a transport robot 83 and transported to a positioning table 84. The positioning table 84 positions the workpiece Q. The positioned workpiece Q is transported by the first transport unit 73 from the positioning table 84 to the holding table 71 in the transport area, and is held by suction on the holding surface of the holding table 71.

[0060] The turntable 70 is rotated to move the holding table 71 holding the unground workpiece Q from the transfer area to the first processing area. In the first processing area, the first grinding unit 50 performs rough grinding on the workpiece Q. The spindle 51 is rotated, and the lifting mechanism 56 is operated to lower the first grinding unit 50. The holding table 71 is also rotated. Then, the rotating grinding wheel 54 is brought into contact with the grinding surface Qa of the rotating workpiece Q to perform rough grinding. Once rough grinding is complete, the lifting mechanism 56 is operated to raise the first grinding unit 50, and the grinding wheel 54 is separated from the workpiece Q.

[0061] Next, the turntable 70 is rotated to move the holding table 71 holding the workpiece Q after rough grinding from the first processing area to the second processing area. In the second processing area, the second grinding unit 60 performs finish grinding on the workpiece Q. The spindle 61 is rotated, and the lifting mechanism 66 is operated to lower the second grinding unit 60. The holding table 71 is also rotated. Then, the rotating grinding wheel 64 is brought into contact with the grinding surface Qa of the rotating workpiece Q to perform finish grinding. Once finish grinding is completed, the lifting mechanism 66 is operated to raise the second grinding unit 60, and the grinding wheel 64 is separated from the workpiece Q.

[0062] During finish grinding, the irradiation unit 75 is positioned above the workpiece Q and irradiates light downward, modifying the grinding surface Qa and reducing the grinding load. The irradiation unit 75 is disposed on the outer periphery of the grinding wheel 64 of the second grinding unit 60 and extending radially from the holding table 71 in the second processing area, with one longitudinal end of the irradiation unit 75 positioned above the center of the holding table 71. The position of the irradiation unit 75 is adjusted by a horizontal movement mechanism built into the base 76 and an elevating mechanism 78 provided between the irradiation unit 75 and the support arm 77, and is maintained in an optimal position for irradiating light toward the grinding surface Qa. Note that, since the workpiece Q is not attached to or detached from the holding table 71 in the second processing area, the irradiation unit 75 may remain in the same position after finish grinding without retracting from above the holding table 71, provided that the rotation of the turntable 70 and the elevation movement of the second grinding unit 60 are not impeded.

[0063] Next, the turntable 70 is rotated to move the holding table 71 holding the workpiece Q after finish grinding from the second processing area to the transfer area. The workpiece Q after finish grinding held on the holding table 71 moved to the transfer area is transferred to the cleaning unit 85 by the second transfer section 74. In the cleaning unit 85, the workpiece Q is cleaned. The cleaned workpiece Q is transferred from the cleaning unit 85 to the cassette 81 by the transfer robot 83 and stored in the cassette 81.

[0064] In this way, a series of processes are performed on the workpiece Q in the grinding device 3. Light is irradiated onto the workpiece Q from the irradiation unit 75, and finish grinding is performed in a state in which the grinding surface Qa has been surface-modified. This improves the processing efficiency of finish grinding, which tends to have a higher grinding load compared to rough grinding because it uses a grinding wheel containing abrasive grains with a smaller particle size, and also reduces wear on the grinding wheel 64. Note that an irradiation unit similar to the irradiation unit 75 may also be installed in the first processing region, and light may be irradiated onto the workpiece Q from the irradiation unit during rough grinding to modify the grinding surface Qa.

[0065] As described above, according to the grinding device and grinding method of each embodiment, the grinding surface Qa of the workpiece Q is oxidized and modified by irradiating it with light of a short wavelength of 385 nm or less, and then grinding the workpiece Q with a grinding wheel, thereby reducing the grinding load and suppressing wear on the grinding wheel. Furthermore, since the irradiation unit is positioned opposite the exposed portion of the grinding surface Qa of the workpiece Q and light is directly irradiated from the irradiation unit toward the exposed area of ​​the grinding surface Qa, the grinding surface Qa can be efficiently modified.

[0066] The embodiments of the present invention are not limited to the above-described embodiments and modifications, and may be variously changed, substituted, or modified without departing from the spirit of the technical idea of ​​the present invention. Furthermore, if the technical idea of ​​the present invention can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention. [Industrial Applicability]

[0067] The grinding device and grinding method of the present invention can reduce wear on the grinding wheel and achieve efficient grinding, which greatly contributes to improving the manufacturing efficiency and reducing the manufacturing costs of semiconductor devices and other devices that use workpieces made of difficult-to-grind materials as their base material. [Explanation of symbols]

[0068] 1: Grinding equipment 2: Grinding equipment 3: Grinding equipment 10: Holding table 15: Grinding unit 16: Spindle 19: Grinding wheel 22: Irradiation unit 23:Light source 24: Irradiation part support mechanism 25: Base part 26: Support arm 29: Irradiation unit 30:Liquid supply section 33: Supply port 35:Liquid supply section 37: Liquid supply nozzle 38: Supply port 40:Liquid supply section 50: First grinding unit 54: Grinding wheel 60: Second grinding unit 64: Grinding wheel 70: Turntable 71: Holding table 75: Irradiation unit 76: Base part 77: Support arm Q: Workpiece Qa: Grinding surface W: Grinding wheel

Claims

1. an irradiation unit that irradiates the workpiece with light having a wavelength of 385 nm or less; a grinding unit that grinds the workpiece irradiated with the light by the irradiation unit; A grinding device comprising:

2. The grinding unit has a grinding wheel fixed to an annular base; The irradiation unit is disposed on the inner periphery side of the annular base.

2. The grinding device according to claim 1.

3. the grinding unit is disposed opposite the workpiece so that a portion of the grinding surface of the workpiece is exposed; The irradiation unit irradiates the light onto the grinding surface in the area exposed from the grinding unit.

2. The grinding device according to claim 1.

4. The irradiation unit is disposed so as to extend in the radial direction of the workpiece.

2. The grinding device according to claim 1.

5. A liquid supply unit is provided to supply liquid to the area of ​​the workpiece where the light is irradiated.

2. The grinding device according to claim 1.

6. Irradiating the workpiece with light having a wavelength of 385 nm or less; grinding the region of the grinding surface of the workpiece that has been modified by irradiating it with light; A grinding method comprising:

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