Grinding equipment

Abstract

To provide a grinding device capable of efficiently cleaning a workpiece held on a chuck table and suppressing scattering of cleaning water around.SOLUTION: This grinding device for grinding the surface of a workpiece comprises: a grinding unit provided with a grinding wheel having an annularly disposed grindstone at the tip of a spindle; a chuck table having a holding surface on which the workpiece can be held; a process-feeding mechanism for moving the chuck table and the grinding unit relative to each other in a process-feeding direction; and a nozzle which is connected to a liquid supply source and a gas supply source and through which grinding water can be supplied to the workpiece held on the chuck table. Through the nozzle, water supplied from the liquid supply source and a mixed fluid mixing the water supplied from the liquid supply source and a gas supplied from the gas supply source can be switched to be injected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a grinding device for grinding a workpiece. [Background technology]

[0002] The device chip manufacturing process uses a wafer in which devices are formed in multiple areas defined by multiple intersecting streets (planned division lines). By dividing this wafer along the streets, multiple device chips, each equipped with a device, are obtained. The device chips are incorporated into various electronic devices, such as mobile phones and personal computers.

[0003] In recent years, the miniaturization of electronic devices has led to a demand for thinner device chips. To address this demand, a process of thinning wafers by grinding them using a grinding device is sometimes carried out. The grinding device includes a chuck table with a holding surface for holding the workpiece, and a grinding unit for grinding the workpiece. The grinding unit includes a spindle, the tip of which is fitted with a grinding wheel containing multiple grinding stones.

[0004] When grinding a workpiece such as a wafer using a grinding device, the relative positions of the chuck table and grinding unit are adjusted so that the center of the workpiece held by the chuck table overlaps the trajectory of the grinding wheel. Then, while the chuck table and grinding wheel are rotated, the grinding wheel is lowered along a processing feed direction (vertical direction) that is roughly parallel to the rotation axis of the spindle. This brings the bottom surface of the grinding wheel into contact with the top surface of the workpiece, grinding it. This type of grinding method is called in-feed grinding.

[0005] Meanwhile, a grinding method called creep feed grinding is sometimes used to grind workpieces. In creep feed grinding, the grinding wheel is positioned outside the workpiece, and the positional relationship between the chuck table and the grinding unit is adjusted so that the bottom surface of the grinding wheel is positioned below the top surface of the workpiece. Then, while rotating the grinding wheel, the chuck table is moved along a processing feed direction (horizontal direction) that is approximately perpendicular to the rotation axis of the spindle. As a result, the side of the grinding wheel comes into contact with the workpiece, grinding the top of the workpiece (see Patent Document 1).

[0006] When a grinding wheel comes into contact with a workpiece and grinds it, the grinding wheel and the workpiece wear out, generating chips. Furthermore, processing heat is generated at the point of contact between the grinding wheel and the workpiece. Therefore, grinding machines are equipped with nozzles that spray a liquid called grinding water near the point of contact between the grinding wheel and the workpiece, and by spraying the grinding water from the nozzle near the point of contact, the processing heat and chips are removed.

[0007] The grinding machine also has a box-shaped cover member called a water case that prevents the grinding water sprayed onto the workpiece from splashing around. The water case covers the area where the workpiece is ground. In the grinding machine, the chuck table that holds the workpiece is sent inside the water case, the workpiece is ground inside the water case, and then the chuck table is sent out of the water case. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-28550 Summary of the Invention [Problem to be solved by the invention]

[0009] If grinding water that has absorbed machining debris remains on the surface of the workpiece, the workpiece may dry outside the water case, causing the machining debris to adhere to the workpiece. To address this issue, a possible solution is to provide a nozzle in the grinding machine near the outer edge of the water case that sprays cleaning water onto the workpiece held on the chuck table. In this case, the workpiece can be cleaned by spraying cleaning water from the nozzle onto it as the chuck table moves from inside the water case to the outside.

[0010] However, it is not easy to install nozzles capable of spraying cleaning water in the limited space inside the water case. Furthermore, installing the nozzles is costly. Furthermore, the water case is open at least along the path of the chuck table. Because the workpiece held by the chuck table is sprayed with cleaning water while moving out of the water case, the cleaning water is prone to splashing outside, unlike grinding water, which is supplied to an area firmly covered by the water case.

[0011] The present invention has been made in consideration of such problems, and aims to provide a grinding device that can efficiently clean workpieces held on a chuck table while suppressing the scattering of cleaning water into the surrounding area. [Means for solving the problem]

[0012] According to one aspect of the present invention, a grinding device for grinding the surface of a workpiece includes a grinding unit having a grinding wheel with grinding stones arranged annularly at the tip of a spindle, a chuck table having a holding surface capable of holding the workpiece, a processing feed mechanism for relatively moving the chuck table and the grinding unit in a processing feed direction, and a nozzle connected to a liquid supply source and a gas supply source and capable of supplying a fluid to the workpiece held by the chuck table, wherein the nozzle can selectively spray water supplied from the liquid supply source and a mixed fluid of water supplied from the liquid supply source and gas supplied from the gas supply source. When the workpiece held by the chuck table is being ground by the grinding unit, grinding water is sprayed as the fluid from the nozzle, and when the workpiece is not being ground by the grinding unit, the mixed fluid is sprayed from the nozzle toward the holding surface to clean the workpiece or the holding surface. The present invention provides a grinding device characterized by the above.

[0013] Preferably, the processing feed direction is a direction parallel to the holding surface, or the processing feed direction is a direction perpendicular to the holding surface.

[0014] Preferably, when the workpiece held by the chuck table is being ground by the grinding unit, grinding water is sprayed as the fluid from the nozzle, and when the workpiece is not being ground by the grinding unit, the mixed fluid is sprayed from the nozzle toward the holding surface to clean the workpiece or the holding surface.

[0016] Preferably, the nozzle is disposed outside the grinding unit, and the nozzle has a jet opening disposed along a direction intersecting the processing feed direction.

[0017] More preferably, the apparatus further comprises a lifting mechanism for raising and lowering the grinding unit, and the lifting mechanism is operated to lower the grinding unit and move the grinding wheel in front of the nozzle, and the liquid or mixed fluid is sprayed from the nozzle onto the grinding wheel to clean the grinding wheel, and the gas is sprayed from the nozzle onto the grinding wheel to dry the grinding wheel. [Effects of the Invention]

[0018] A grinding apparatus according to one aspect of the present invention includes a nozzle connected to a liquid supply source and a gas supply source and capable of supplying grinding water to a workpiece held by a chuck table. The nozzle can switch between spraying water and a mixture of water and gas. Therefore, when grinding the workpiece, the nozzle can spray grinding water to supply the grinding water to the workpiece. After grinding of the workpiece is completed, the mixture of water and gas can be supplied to the workpiece on the spot to clean the workpiece.

[0019] In this case, there is no need to install a new nozzle just for spraying the mixed fluid in addition to the nozzle for supplying grinding water, which eliminates unnecessary costs. Furthermore, the space inside the water case is not constricted. Furthermore, the mixed fluid can be sprayed from the nozzle onto the workpiece in the area inside the water case where grinding is performed. In other words, because the mixed fluid is sprayed in an area firmly covered by the water case, the water contained in the mixed fluid is less likely to splash outside the water case.

[0020] Therefore, according to one aspect of the present invention, a grinding device is provided that can efficiently clean a workpiece held by a chuck table and also suppresses the scattering of cleaning water into the surrounding area. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a perspective view schematically showing a grinding device. [Figure 2] FIG. 2 is a cross-sectional side view schematically showing a part of the grinding device. [Figure 3] FIG. 2 is a side view schematically showing the chuck table and the grinding unit before grinding is performed. [Figure 4] FIG. 2 is a side view schematically showing a grinding unit that grinds a workpiece. [Figure 5] FIG. 5(A) is a side view schematically showing a nozzle spraying a mixed fluid onto a workpiece, and FIG. 5(B) is a side view schematically showing a nozzle spraying a gas onto a workpiece. [Figure 6] FIG. 6(A) is a side view schematically showing a nozzle spraying a mixed fluid onto the holding surface of a chuck table, and FIG. 6(B) is a side view schematically showing a nozzle spraying a mixed fluid onto a grinding wheel. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of the present invention will be described below with reference to the accompanying drawings. First, a configuration example of a grinding device according to this embodiment will be described. In particular, a grinding device capable of performing creep feed grinding on a workpiece will be described as an example, but the grinding device according to this embodiment is not limited to this and may also be a grinding device capable of performing in-feed grinding on a workpiece.

[0023] Fig. 1 is a perspective view showing a grinding device 2. In Fig. 1, the X-axis direction (processing feed direction, first horizontal direction, front-rear direction) and the Y-axis direction (second horizontal direction, left-right direction) are perpendicular to each other. Also, the Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0024] The grinding device 2 includes a base 4 that supports or houses each of the components that make up the grinding device 2. A rectangular parallelepiped opening 4a is provided on the top surface of the base 4, with its longitudinal direction aligned with the X-axis direction. Furthermore, a rectangular parallelepiped support structure 6 is provided on the rear end of the top surface of the base 4, aligned with the Z-axis direction.

[0025] A chuck table (holding table) 8 is provided inside the opening 4a to hold a workpiece that is an object to be processed by the grinding device 2. The upper surface of the chuck table 8 is a flat surface that is roughly parallel to the horizontal plane (XY plane) and forms a holding surface 8a that holds the workpiece. In addition, a processing feed mechanism (moving unit) 10 that moves the chuck table 8 along the processing feed direction (X-axis direction) is connected to the chuck table 8.

[0026] Fig. 2 is a partial cross-sectional side view showing the grinding device 2. Note that Fig. 2 does not show some of the components of the grinding device 2. As shown in Fig. 2, the processing feed mechanism 10 is provided inside the opening 4a of the base 4.

[0027] The processing feed mechanism 10 includes a flat movable plate 12 that supports a chuck table 8. A nut portion 14 is provided on the back side (lower surface side) of the movable plate 12. A ball screw 16 arranged along the X-axis direction is threadedly engaged with the nut portion 14. A pulse motor 18 that rotates the ball screw 16 is connected to the end of the ball screw 16. The chuck table 8 is mounted on the front side (upper surface side) of the movable plate 12. When the pulse motor 18 rotates the ball screw 16, the chuck table 8 and the movable plate 12 move along the X-axis direction.

[0028] The grinding device 2 may move a grinding unit 36, which will be described later, along the X-axis direction instead of the chuck table 8. In other words, the grinding device 2 has a processing feed mechanism that moves the chuck table 8 and the grinding unit 36 ​​relatively in the processing feed direction (X-axis direction).

[0029] Furthermore, a rotation drive source (not shown) such as a motor that rotates the chuck table 8 around a rotation axis that is substantially perpendicular to the holding surface 8a (a rotation axis that is substantially parallel to the Z-axis direction) may be connected to the chuck table 8. In this case, the rotation axis of the chuck table 8 is set along a direction perpendicular to the holding surface 8a.

[0030] 1, a table cover 20 is provided around the chuck table 8 to surround the chuck table 8. In addition, accordion-shaped dust-proof and drip-proof covers 22 that are extendable and contractible along the X-axis direction are provided in front and behind the table cover 20. The table cover 20 and the dust-proof and drip-proof covers 22 cover the components of the processing feed mechanism 10 provided inside the opening 4a.

[0031] An elevation mechanism (movement unit) 24 is provided on the front side of the support structure 6. The elevation mechanism 24 includes a pair of guide rails 26 arranged along the Z-axis direction. A flat moving plate 28 is attached to the pair of guide rails 26 so as to be slidable along the guide rails 26.

[0032] A nut portion (not shown) is provided on the back surface (rear surface) side of the moving plate 28. A ball screw 30, which is disposed along the Z-axis direction between the pair of guide rails 26, is threadedly engaged with this nut portion. A pulse motor 32 that rotates the ball screw 30 is connected to the end of the ball screw 30. When the ball screw 30 is rotated by the pulse motor 32, the moving plate 28 moves (moves up and down) along the guide rails 26 in the Z-axis direction.

[0033] A support member 34 is fixed to the movable plate 28, protruding forward from the surface (front surface) of the movable plate 28. The support member 34 supports a grinding unit 36 ​​that performs grinding on the workpiece 11. The grinding unit 36 ​​includes a cylindrical housing 38 supported by the support member 34. The housing 38 also houses a cylindrical spindle 40 that is arranged generally along the Z-axis direction.

[0034] The tip (lower end) of the spindle 40 protrudes downward from the lower surface of the housing 38. A disk-shaped mount 42 made of metal or the like is fixed to the tip of the spindle 40. A rotation drive source (not shown), such as a motor, that rotates the spindle 40 is connected to the base (upper end) of the spindle 40.

[0035] An annular grinding wheel 44 for grinding the workpiece 11 is attached to the underside of the mount 42. For example, the grinding wheel 44 is fixed to the mount 42 by a fastener (not shown) such as a bolt. As a result, the grinding wheel 44 is attached to the tip of the spindle 40 via the mount 42.

[0036] The grinding wheel 44 includes an annular wheel base 46 and a plurality of grinding stones 48 fixed to the wheel base 46. The wheel base 46 is made of a metal such as stainless steel or aluminum, or a resin, and is formed to have approximately the same diameter as the mount 42. The plurality of grinding stones 48, each formed in the shape of a rectangular parallelepiped, are arranged on the underside of the wheel base 46 in an annular shape at approximately equal intervals along the outer periphery of the wheel base 46.

[0037] The grinding wheel 48 includes abrasive grains made of diamond, cBN (cubic boron nitride), or the like, and a bonding material (bond material) that secures the abrasive grains. Bonds that can be used include metal bonds, resin bonds, and vitrified bonds. However, there are no limitations on the material, shape, structure, size, etc., of the grinding wheel 48, and the number of grinding wheels 48 fixed to the wheel base 46 can be set as desired.

[0038] The grinding wheel 44 rotates around a rotation axis that is roughly parallel to the Z-axis direction by power transmitted from the rotation drive source via the spindle 40 and the mount 42. In other words, the rotation axis of the grinding wheel 44 is set along a direction parallel to the rotation axis of the spindle 40.

[0039] A columnar nozzle 50 is provided in front of the grinding unit 36 ​​to supply liquid (grinding water) such as pure water to the grinding unit 36. The nozzle 50 is positioned above the opening 4a of the base 4 so as to overlap with the movement path of the chuck table 8.

[0040] The nozzle 50 is configured, for example, by a pipe, tube, or the like whose length is approximately the same as the diameter of the holding surface 8a of the chuck table 8, and is arranged generally along the width direction (Y-axis direction) of the opening 4a (a direction intersecting the processing feed direction). However, the nozzle 50 does not need to be strictly parallel to the Y-axis direction, nor does it need to be linear. The nozzle 50 may be aligned in a direction that does not coincide with the Y-axis direction, or may be curved or arc-shaped. In particular, if the nozzle 50 is shaped like an arc that equidistantly surrounds part of the outer periphery of the mount 42, the fluid can be supplied uniformly to a predetermined area.

[0041] The nozzle 50 has an outlet 50d on the side facing the grinding unit 36. The outlets 50d are, for example, arranged at predetermined intervals along a direction intersecting the processing feed direction and are configured as a plurality of fine holes or slits provided in the nozzle 50. Alternatively, the outlet 50d may be configured as a linear opening that is long in the direction intersecting the processing feed direction. There are no particular limitations on the shape and configuration of the outlet 50d, as long as the shape and configuration allow the fluid ejected from the outlet 50d to travel through the air with a predetermined force. There are also no particular limitations on the position of the outlet 50d.

[0042] The fluid is sprayed in a strip or columnar shape from the nozzle 50d. As a result, the grinding water 50a is supplied from the outside of the grinding wheel 44 to the area (processing area) where the workpiece 11 and the grinding wheel 48 come into contact with each other, as will be described later with reference to Fig. 4. This cools the workpiece 11 and the grinding wheel 48, and also washes away chips (processing chips) generated by the grinding process.

[0043] Furthermore, there are no limitations on the method of installing the nozzle 50. For example, the nozzle 50 is fixed to the upper surface of the base 4 or the grinding unit 36 ​​via a predetermined connecting member (not shown). Alternatively, the nozzle 50 does not need to be provided outside the grinding unit 36, but may be arranged in an area inside the annularly arranged grinding wheels 48 and have an injection hole facing the grinding wheels 48. Below, an example will be described in which the nozzle 50 is arranged outside the grinding unit 36.

[0044] The nozzle 50 is connected to a liquid supply source 54 via a valve 52. For example, an electromagnetic valve is used as the valve 52. The liquid supply source 54 is, for example, factory equipment (liquid supply equipment) installed in a factory where the grinding apparatus 2 is installed, and supplies a liquid such as pure water to be used as grinding water. The liquid supplied from the liquid supply source 54 may contain additives or the like having predetermined functions. The flow rate of the liquid supplied from the liquid supply source 54 to the nozzle 50 is adjusted by controlling the opening / closing or the degree of opening of the valve 52.

[0045] The nozzle 50 is connected to a gas supply source 58 via a valve 56. For example, an electromagnetic valve is used as the valve 56. The gas supply source 58 is, for example, factory equipment (gas supply equipment) such as a pump or a cylinder provided in the factory where the grinding apparatus 2 is installed, and supplies high-pressure gas such as air, dry air, nitrogen, or a rare gas. By controlling the opening / closing or opening degree of the valve 56, the flow rate of the gas supplied from the gas supply source 58 to the nozzle 50 is adjusted.

[0046] When only valve 52 is opened, only the liquid supplied to nozzle 50 from liquid supply source 54 reaches nozzle 50 and is ejected from outlet 50d. When only valve 56 is opened, only the gas supplied to nozzle 50 from gas supply source 58 reaches nozzle 50 and is ejected from outlet 50d. When valves 52 and 56 are opened, a mixed fluid of the liquid supplied from liquid supply source 54 and the gas supplied from gas supply source 58 reaches nozzle 50 and is ejected from outlet 50d.

[0047] Next, a specific example of a method for grinding a workpiece using the grinding device 2 will be described. As an example, creep feed grinding will be described below, in which the chuck table 8 and the grinding wheel 44 are moved relatively in a direction parallel to the holding surface 8a (X-axis direction) to grind the workpiece.

[0048] First, the workpiece 11 is held by the chuck table 8 (holding step). Fig. 3 is a side view showing the chuck table 8 and the grinding unit 36 ​​in the holding step.

[0049] For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as silicon, and has a front surface 11a and a back surface 11b that are generally parallel to each other. The workpiece 11 is divided into a plurality of rectangular regions by a plurality of streets (planned division lines) that are arranged in a grid pattern so as to intersect with each other. Furthermore, devices such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed on the front surface 11a side of each of the regions divided by the streets.

[0050] A plurality of device chips each equipped with a device are manufactured by dividing the workpiece 11 along the streets by cutting, laser processing, etc. Furthermore, if the workpiece 11 is ground and thinned by the grinding device 2 before being divided, thinned device chips can be obtained.

[0051] However, there are no limitations on the type, material, size, shape, structure, etc. of the workpiece 11. For example, the workpiece 11 may be a disk-shaped wafer (substrate) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of devices, and the workpiece 11 does not necessarily have to have any devices formed thereon.

[0052] For example, the workpiece 11 is placed on the chuck table 8 so that the front surface 11a faces the holding surface 8a and the back surface 11b is exposed upward. The holding surface 8a of the chuck table 8 is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like formed inside the chuck table 8. When the suction force (negative pressure) of the suction source is applied to the holding surface 8a, the workpiece 11 is sucked and held by the chuck table 8.

[0053] A protective member may be attached to the front surface 11a of the workpiece 11 to protect devices and the like formed on the front surface 11a of the workpiece 11. In this case, the workpiece 11 is held by the chuck table 8 via the protective member.

[0054] For example, a tape (protective tape) formed into a circle having approximately the same diameter as the workpiece 11 is used as the protective member. The protective tape includes a film-like substrate and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. The adhesive layer may also be made of an ultraviolet-curable resin that hardens when exposed to ultraviolet light.

[0055] Next, the workpiece 11 is ground with the grinding stone 48 of the grinding wheel 44 (grinding step). In the grinding step, first, the positional relationship between the chuck table 8 and the grinding unit 36 ​​is adjusted so that the workpiece 11 held by the chuck table 8 and the grinding stone 48 are spaced apart from each other in the processing feed direction (X-axis direction) and the lower surface of the grinding stone 48 is positioned a predetermined distance below the upper surface (rear surface 11b) of the workpiece 11.

[0056] Specifically, the position of the chuck table 8 in the X-axis direction is adjusted by the processing feed mechanism 10 (see FIGS. 1 and 2) so that the workpiece 11 is positioned in front of the grinding wheel 44 (on the left side of the paper in FIG. 3) without overlapping with the grinding wheel 44. In addition, the position of the grinding unit 36 ​​in the Z-axis direction is adjusted by the lifting mechanism 24 (see FIG. 1) so that the lower surface of the grinding wheel 48 is positioned lower than the upper surface of the workpiece 11. The difference ΔH in height (position in the Z-axis direction) between the upper surface of the workpiece 11 and the lower surface of the grinding wheel 48 at this time corresponds to the target value of the grinding amount of the workpiece 11 (the difference in thickness of the workpiece 11 before and after grinding).

[0057] Next, the chuck table 8 and the grinding unit 36 ​​are moved relatively along the processing feed direction (X-axis direction) while rotating the grinding wheel 44, and the workpiece 11 is ground from one end side to the other end side by the grinding stone 48. Specifically, first, the spindle 40 is rotated to rotate the grinding wheel 44 around the rotation axis of the spindle 40. As a result, each of the multiple grinding stones 48 rotates along an annular orbit (movement path). The rotation speed of the grinding wheel 44 is set to, for example, 1000 rpm or more and 3000 rpm or less.

[0058] Then, with the grinding wheel 44 rotating and the chuck table 8 not rotating, the chuck table 8 is moved at a predetermined speed along the X-axis direction by the processing feed mechanism 10 (see FIGS. 1 and 2). As a result, the chuck table 8 and the grinding wheel 44 move relatively at the predetermined processing feed speed along the processing feed direction perpendicular to the rotation axis of the spindle 40, and approach each other. The movement speed (processing feed speed) of the chuck table 8 is set, for example, to be equal to or greater than 1 mm / s and equal to or less than 20 mm / s.

[0059] 4 is a side view showing the grinding unit 36 ​​that grinds one end of the workpiece 11. When the chuck table 8 moves and one end of the workpiece 11 (the front end in the movement direction of the workpiece 11, the right end on the paper in FIG. 4) reaches the orbit of the grinding wheel 48, the one end of the workpiece 11 is ground away by the grinding wheel 48.

[0060] As the chuck table 8 moves, each area of ​​the workpiece 11 comes into contact with the grinding wheel 48 in turn, and grinding of the workpiece 11 progresses. Then, the workpiece 11 is ground from one end side to the other end side by the grinding wheel 48, and the entire workpiece 11 is thinned.

[0061] Furthermore, grinding of the workpiece 11 is repeated until the thickness of the workpiece 11 reaches the final target thickness (finish thickness). The number of times creep feed grinding is performed (the number of times the grinding step is performed) can be set appropriately depending on the material of the workpiece 11, the amount of grinding, etc.

[0062] While the workpiece 11 is being ground, grinding water 50a such as pure water is supplied to the workpiece 11 and the grinding wheel 48 from the outlet 50d of the nozzle 50. Grinding dust and processing heat generated when the workpiece 11 is ground by the grinding wheel 48 are removed by the grinding water 50a. However, if the grinding water 50a supplied to the workpiece 11, etc., splashes inside and outside the grinding device 2, it can cause contamination, so the grinding device 2 is provided with a water case (not shown) that prevents the scattering of the grinding water 50a.

[0063] The water case covers, for example, the grinding area where grinding wheel 48 contacts workpiece 11 and grinding is performed, and largely closes off the internal space except for the movement path of chuck table 8. Workpiece 11 to be ground is placed on chuck table 8 outside the water case, and is carried into the water case while held by chuck table 8 and ground. Then, after grinding is completed, workpiece 11 is carried out of the water case while held by chuck table 8.

[0064] The workpiece 11, which has been held on the chuck table 8 and ground, is washed (washing step). However, since grinding water containing grinding debris remains on the back surface 11b of the workpiece 11 immediately after grinding, if the grinding water dries before the workpiece 11 is washed outside the water case, the grinding debris will adhere to the back surface 11b. Therefore, it is conceivable to provide a washing unit inside the water case to wash the workpiece 11. However, it is not easy to provide a washing unit in the limited internal space.

[0065] For example, it is conceivable to provide a cleaning nozzle on the outer edge of the internal space of the water case, and supply cleaning water from the cleaning nozzle to the workpiece 11 as the chuck table 8 moves from this internal space to the outside. However, if cleaning water is sprayed from the outer edge of the internal space of the water case, it is likely to splash out from the opening of the water case and cause contamination. Cleaning water composed of a mixture of water and high-pressure air is particularly prone to splashing. Furthermore, installing additional cleaning nozzles inside the water case is costly.

[0066] Therefore, the grinding device 2 according to this embodiment uses a nozzle 50 capable of spraying water as grinding water 50a onto the grinding area to wash the workpiece 11 held on the chuck table 8. The procedure (washing step) for washing the workpiece 11 held on the chuck table 8 will be described. Fig. 5(A) includes a side view that schematically shows the workpiece 11 being washed.

[0067] 5(A), when grinding of the workpiece 11 is completed, the lifting mechanism (moving unit) 24 is operated to raise the grinding unit 36. Then, the valves 52 and 56 (see FIG. 1) are opened, and a mixed fluid 50b of a liquid such as water supplied from a liquid supply source 54 and a gas supplied from a gas supply source 58 is sprayed as cleaning water from the outlet 50d of the nozzle 50. Thereafter, the processing feed mechanism (moving unit) 10 is operated to move the chuck table 8 back and forth along the processing feed direction, while spraying the mixed fluid 50b onto the back surface 11b of the workpiece 11.

[0068] When the mixed fluid 50b is forcefully sprayed onto the back surface 11b of the workpiece 11, the grinding water containing grinding debris is removed from the back surface 11b. Therefore, even if the workpiece 11 dries thereafter, the grinding debris will not adhere to the back surface 11b of the workpiece 11. The mixed fluid 50b is sprayed from the nozzle 50 onto the workpiece 11 in the vicinity of the grinding area where grinding was performed. Because the grinding area is sufficiently covered by the water case, even if the mixed fluid 50b is sprayed forcefully onto the workpiece 11, the water contained in the mixed fluid 50b is unlikely to splash out of the water case.

[0069] Furthermore, in the case where creep feed grinding is performed in stages by passing the workpiece 11 below the rotating grinding wheel 44 while sequentially lowering the grinding units 36 in the grinding apparatus 2, the workpiece 11 may be washed with the mixed fluid 50b at each grinding stage. That is, the workpiece 11 is ground while the chuck table 8 is fed in the forward processing feed direction, and the mixed fluid 50b is sprayed onto the workpiece 11 while the chuck table 8 is fed in the reverse processing feed direction to wash the workpiece 11. Then, the grinding unit 36 ​​is lowered, and the next stage is performed.

[0070] Cleaning the workpiece 11 in this manner at each stage of creep feed grinding, which is performed in stages, prevents situations such as grinding chips remaining on the back surface 11b of the workpiece 11 becoming caught between the grinding wheel 48 and the workpiece 11 and damaging the workpiece 11. In conventional creep feed grinding performed in stages, the chuck table 8 has been moved back and forth, but in the grinding device 2 according to this embodiment, the workpiece 11 can be cleaned during this reciprocating movement. Therefore, the number of operations of the chuck table 8 does not increase, and the time required for grinding does not increase.

[0071] Furthermore, in the grinding device 2 according to this embodiment, cleaning can be performed at each stage of creep feed grinding without having to sequentially remove the workpiece 11 from the water case for cleaning, so that the workpiece 11 can be efficiently cleaned while being ground to a high quality.

[0072] Furthermore, the nozzle 50 can be used to dry the cleaned workpiece 11 (drying step). FIG. 5(B) includes a side view that schematically shows the workpiece 11 being dried. In the drying step, only the valve 56 (see FIG. 1) is opened, and high-pressure gas 50c supplied from the gas supply source 58 is sprayed from the nozzle 50d. Thereafter, the processing feed mechanism (moving unit) 10 is operated to move the chuck table 8 back and forth along the processing feed direction, while spraying the gas 50c onto the back surface 11b of the workpiece 11.

[0073] If the workpiece 11 is dried, when the workpiece 11 is carried out of the chuck table 8 outside the water case, the water contained in the mixed fluid 50b used for washing will not drip from the workpiece 11 and become a source of contamination. In addition, there is no need to wash and dry the workpiece 11 outside the grinding device 2.

[0074] To summarize the functions utilizing the nozzle 50 of the grinding device 2 according to this embodiment described so far, the grinding device 2 sprays water or the like as grinding water from the nozzle 50 when the workpiece 11 held by the chuck table 8 is being ground by the grinding unit 36.

[0075] Furthermore, the grinding device 2 sprays the mixed fluid 50b from the nozzle 50 toward the holding surface 8a to clean the workpiece 11 when the workpiece 11 is not being ground by the grinding unit 36. Furthermore, the grinding device 2 sprays the gas 50c from the nozzle 50 toward the workpiece 11 from the nozzle 50 to dry the workpiece 11 when the workpiece 11 held by the chuck table 8 is not being ground by the grinding unit 36.

[0076] In the grinding apparatus 2 according to this embodiment, there is no need to provide a new nozzle for spraying the mixed fluid 50b in addition to the nozzle 50 for supplying grinding water, which eliminates unnecessary costs. Furthermore, the space inside the water case is not constricted. According to one aspect of the present invention, a grinding apparatus 2 is provided that can efficiently clean the workpiece 11 held by the chuck table 8 and also suppresses the scattering of cleaning water around the workpiece 11.

[0077] In the above embodiment, the case where the fluid such as the grinding water 50a, the mixed fluid 50b, or the gas 50c is sprayed from the nozzle 50 outlet 50d of the nozzle 50 onto the workpiece 11 held on the chuck table 8 has been described, but one aspect of the present invention is not limited to this. That is, the fluid sprayed from the nozzle 50 may be supplied to the target of the workpiece 11.

[0078] For example, the grinding device 2 may clean the holding surface 8a by spraying the mixed fluid 50b from the ejection port 50d of the nozzle 50 onto the holding surface 8a of the chuck table 8 that is not holding the workpiece 11. Fig. 6(A) is a side view that schematically shows how the holding surface 8a of the chuck table 8 is cleaned.

[0079] When the grinding device 2 grinds the workpieces 11 one after another, grinding chips may accumulate on the outer periphery of the holding surface 8a that is not covered by the workpieces 11. Then, as the workpieces 11 are repeatedly loaded and unloaded onto the chuck table 8, the accumulated grinding chips may scatter toward the center of the holding surface 8a. In this case, the grinding chips are caught between the workpiece 11 and the holding surface 8a, and the workpiece 11 is held on the chuck table 8 in an inclined state. If the back surface 11b of the workpiece 11 is ground in this state, an inappropriate inclination of the back surface 11b occurs.

[0080] Therefore, it is necessary to periodically clean the holding surface 8a of the chuck table 8. The grinding device 2 according to this embodiment can clean the holding surface 8a by moving the chuck table 8 back and forth using the processing feed mechanism 10 while spraying the fluid mixture 50b from the nozzle 50. Therefore, it is not necessary to provide a nozzle that is used only for cleaning the holding surface 8a of the chuck table 8.

[0081] Furthermore, the grinding device 2 may spray the mixed fluid 50b from the outlet 50d of the nozzle 50 onto the grinding wheel 44 attached to the grinding unit 36 ​​to clean the grinding wheel 44. Fig. 6(B) is a side view schematically showing how the grinding wheel 44 is cleaned. In the grinding device 2, the grinding stone 48 wears out as the workpiece 11 is repeatedly ground, so the grinding wheel 44 needs to be replaced periodically.

[0082] However, as the workpiece 11 is repeatedly ground, chips adhere to the spaces between the grinding wheels 48 and to the wheel base 46. Then, in the process of removing the grinding wheel 44 with the chips adhered thereto from the grinding unit 36 ​​and carrying it out of the grinding device 2, the chips may fall off the grinding wheel 44 and contaminate the inside and outside of the grinding device 2.

[0083] Therefore, by washing the grinding wheel 44 with the mixed fluid 50b before removing the grinding wheel 44 from the grinding device 2, contamination caused by falling off of machining debris when the used grinding wheel 44 is removed from the grinding device 2 can be suppressed.

[0084] When cleaning the grinding wheel 44, the lifting mechanism (moving unit) 24 is operated to lower the grinding unit 36 ​​and move the grinding wheel 44 in front of the nozzle 50. Then, the liquid or mixed fluid 50b supplied from the liquid supply source 54 is sprayed from the nozzle 50 onto the grinding wheel 44, thereby cleaning the grinding wheel 44. At this time, by rotating the spindle 40 to rotate the grinding wheel 44 and operating the lifting mechanism 24 to repeatedly raise and lower the grinding wheel 44, the entire grinding wheel 44 can be cleaned uniformly.

[0085] Furthermore, after cleaning the grinding wheel 44, the grinding device 2 can dry the grinding wheel 44 by spraying the gas 50c supplied from the gas supply source 58 from the nozzle 50 onto the grinding wheel 44. In this case, the water contained in the mixed fluid 50b remains on the surface of the grinding wheel 44, and the water falls from the grinding wheel 44 when the grinding wheel 44 is transported from the grinding device 2, which can cause contamination.

[0086] Furthermore, in the above embodiment, the grinding device 2 is described as an example that performs creep feed grinding in which the processing feed direction is parallel to the holding surface 8a of the chuck table 8, but this aspect of the present invention is not limited to this. That is, the grinding device according to one aspect of the present invention may be a grinding device that performs in-feed grinding in which the processing feed direction is perpendicular to the holding surface 8a of the chuck table 8.

[0087] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0088] 11 Workpiece 11a surface 11b Back side 2 Grinding equipment 4 Foundation 4a aperture 6 Support structure 8 Chuck table 8a Holding surface 10 Processing feed mechanism 12 Moving Plate 14 Nut part 16,30 ball screw 18,32 Pulse motor 20 Table Cover 22 Dustproof and water-resistant cover 24 Lifting mechanism 26 Guide rail 28 Moving Plate 34 Support member 36 Grinding unit 38 Housing 40 spindles 42 Mount 44 Grinding Wheel 46 Wheel base 48 Grinding Wheel 50 nozzles 50a Grinding water 50b mixed fluid 50c gas 50d spout 52,56 Valve 54 Liquid Source 58 Gas Supply Source

Claims

1. A grinding device for grinding a surface of a workpiece, comprising: a grinding unit provided with a grinding wheel having grinding stones arranged in a circular pattern at the tip of a spindle; a chuck table having a holding surface capable of holding the workpiece; a processing feed mechanism that moves the chuck table and the grinding unit relatively in a processing feed direction; a nozzle connected to a liquid supply source and a gas supply source and capable of supplying a fluid to the workpiece held by the chuck table; the nozzle can switch between injecting a liquid supplied from the liquid supply source and a mixed fluid of the liquid supplied from the liquid supply source and a gas supplied from the gas supply source, When the workpiece held by the chuck table is being ground by the grinding unit, grinding water is sprayed as the fluid from the nozzle; a grinding device for cleaning the workpiece or the holding surface by spraying the mixed fluid from the nozzle toward the holding surface when the workpiece is not being ground by the grinding unit;

2. 2. The grinding device according to claim 1, wherein the processing feed direction is a direction parallel to the holding surface.

3. 2. The grinding device according to claim 1, wherein the processing feed direction is a direction perpendicular to the holding surface.

4. the nozzle is further capable of injecting the gas supplied from the gas source; 2. The grinding apparatus according to claim 1, wherein the gas is sprayed from the nozzle onto the workpiece to dry it when the workpiece held by the chuck table is not being ground by the grinding unit.

5. 5. The grinding device according to claim 1, wherein the nozzle is disposed outside the grinding unit.

6. 6. The grinding device according to claim 5, wherein the nozzle has a jet port arranged along a direction intersecting the processing feed direction.

7. further comprising a lifting mechanism for lifting and lowering the grinding unit; The grinding device according to claim 5 or 6, characterized in that the lifting mechanism is operated to lower the grinding unit and move the grinding wheel in front of the nozzle, and the liquid or the mixed fluid is sprayed from the nozzle onto the grinding wheel to clean the grinding wheel, and the gas is sprayed from the nozzle onto the grinding wheel to dry the grinding wheel.

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