processing device

Abstract

The present application provides a processing device that suppresses thickness deviation of a wafer after processing. The processing device includes a holding unit that attracts and holds a wafer, a processing unit that has a grinding wheel that grinds the wafer, and a processing liquid supply unit that supplies a processing liquid to the wafer. The holding unit has a chuck table that holds the wafer and a table base that supports the chuck table. The chuck table has a porous plate that has a suction surface that suctions the wafer, a frame that surrounds the outside of the suction surface, a cooling water path that is formed in the inside of the frame and that allows cooling water to pass through, a wafer attraction hole that is formed in the frame and that transmits an attraction force to the suction surface of the porous plate, and a bolt hole that is formed in the frame and that fixes the chuck table to the table base. The table base has a placement surface that places the lower surface side of the frame, a frame attraction hole that is formed in the placement surface and that suctions and holds the frame, and a cooling water supply hole that communicates with the cooling water path.

Description

Technical Field

[0001] The present invention relates to a processing apparatus comprising at least: a holding unit for attracting and holding a wafer; a processing unit having a grinding wheel for grinding the wafer held by the holding unit and the grinding wheel being rotatable; and a processing fluid supply unit for supplying processing fluid to the wafer. Background Technology

[0002] A wafer with multiple devices such as ICs and LSIs formed on its front side by dividing it by predetermined dividing lines is then processed to the desired thickness by grinding the back side. It is then divided into individual device chips by a cutting device and a laser processing device, and used in electronic devices such as mobile phones and personal computers.

[0003] The grinding apparatus includes at least: a holding unit for attracting and holding a wafer; a processing unit having a grinding wheel that is rotatable, the grinding wheel being annularly shaped with a grinding tool for grinding the wafer held by the holding unit; and a processing fluid supply unit for supplying grinding water as a processing fluid to the wafer, the grinding apparatus being capable of processing the wafer to a desired thickness (see, for example, Patent Document 1).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2005-153090

[0005] Furthermore, in the processing apparatus disclosed in Patent Document 1, free abrasive particles can be provided as a processing fluid to the back side of the wafer, and the back side of the wafer can be processed into a mirror surface using a polishing pad. Moreover, the holding unit for attracting and holding the wafer includes: a chuck stage for holding the wafer; and a stage base that supports the chuck stage in a detachable manner. The chuck stage is configured to include: a perforated plate having an adsorption surface for adsorbing the wafer; a frame surrounding the adsorption surface; a wafer attraction hole formed on the bottom surface of the frame to transmit attractive force to the adsorption surface of the perforated plate; and bolt holes formed in the frame and fixed to the stage base. This holding unit is configured to attract and hold the wafer.

[0006] In addition, when processing a wafer in the above-mentioned processing apparatus, the holding surface of the chuck table is ground in advance by the processing unit of the grinding apparatus, so that the shape of the holding surface of the chuck table is the same as the shape of the grinding surface of the wafer placed and held on the chuck table, thereby making the thickness of the wafer uniform throughout the entire area.

[0007] However, it has been established that even when the chuck stage's holding surface is adjusted as described above to perform grinding or polishing of the wafer, a slight thickness deviation (e.g., around 2μm to 3μm) will still occur when measuring the thickness of the processed wafer. In recent years, with wafers becoming extremely thin, such a small deviation has become a significant problem. Summary of the Invention

[0008] Therefore, the object of the present invention is to provide a processing apparatus that, compared with conventional processing apparatus, can suppress thickness deviations in the processed wafer.

[0009] According to one aspect of the present invention, a processing apparatus is provided, comprising: a holding unit for attracting and holding a wafer; a processing unit having a grinding wheel for grinding the wafer held by the holding unit and the grinding wheel being rotatable; and a processing fluid supply unit for supplying processing fluid to the wafer, the holding unit having: a chuck stage for holding the wafer; and a stage base for supporting the chuck stage for easy loading and unloading, the chuck stage having: a perforated plate having an adsorption surface for adsorbing the wafer; The frame surrounds the adsorption surface; a cooling water channel is formed inside the frame and provides cooling water throughout; a wafer attraction hole is formed in the frame to transfer attraction to the adsorption surface of the porous plate; and bolt holes are formed in the frame to fix the chuck stage to the stage base, the stage base having: a mounting surface that supports the lower surface of the frame; a frame attraction hole formed in the mounting surface to attract and hold the frame; and a cooling water supply hole communicating with the cooling water channel to supply cooling water to the cooling water channel.

[0010] Preferably, the wafer attraction hole is formed on the mounting surface of the frame for placing the porous board, and a connecting hole is formed on the mounting surface of the worktable base. The connecting hole communicates with the wafer attraction hole and transmits attraction independently relative to the frame attraction hole. Alternatively, the wafer attraction hole is formed on the side of the frame, and a connecting hole is formed on the side of the worktable base. The connecting hole communicates with the wafer attraction hole and transmits attraction independently relative to the frame attraction hole.

[0011] A processing apparatus according to one aspect of the present invention includes at least: a holding unit for attracting and holding a wafer; a processing unit having a grinding wheel for grinding the wafer held by the holding unit and the grinding wheel being rotatable; and a processing fluid supply unit for supplying processing fluid to the wafer. The holding unit includes: a chuck stage for holding the wafer; and a stage base for supporting the chuck stage for easy loading and unloading. The chuck stage includes: a perforated plate having an adsorption surface for adsorbing the wafer; a frame surrounding the adsorption surface; a cooling water channel formed inside the frame and permeating it with cooling water; and a wafer suction hole formed in the frame, leading to the wafer... The perforated plate's adsorption surface transmits the attractive force; and bolt holes are formed in the frame to fix the chuck stage to the stage base, which has: a mounting surface that supports the lower surface of the frame; a frame suction hole formed in the mounting surface to attract and hold the frame; and a cooling water supply hole communicating with the cooling water passage to supply cooling water. Therefore, in any case, whether grinding the adsorption surface of the perforated plate of the chuck stage or grinding the wafer, the entire area of ​​the chuck stage frame is reliably fixed to the stage base, and grinding of the processing unit is performed while maintaining a specified temperature by cooling water. Thus, the shape of the holding surface of the chuck stage, i.e., the adsorption surface of the perforated plate, is substantially consistent with the shape of the grinding surface of the wafer, which can suppress wafer thickness deviations after grinding. Attached Figure Description

[0012] Figure 1 This is an overall perspective view of the grinding apparatus according to the first embodiment.

[0013] Figure 2 (a) is Figure 1 The diagram shows a perspective view of the grinding apparatus, comprising the chuck, worktable, and worktable base of the holding unit. Figure 2 (b) is an exploded perspective view of the chuck table.

[0014] Figure 3 yes Figure 2 (a) and Figure 2 (b) is a top view of the lower frame that constitutes the retaining unit.

[0015] Figure 4 (a) is installed on Figure 1 A perspective view of the holding unit of the grinding device. Figure 4 (b) is Figure 4 (a) shows a partial schematic cross-sectional view of the retaining unit.

[0016] Figure 5 This is a perspective view showing the method of grinding the adsorption surface of the retaining unit.

[0017] Figure 6 It shows through Figure 1 A perspective view of the grinding apparatus used to grind the back side of a wafer.

[0018] Figure 7 (a) is a perspective view of the chuck table and table base constituting the holding unit of the second embodiment. Figure 7 (b) is an exploded perspective view of the chuck table.

[0019] Figure 8 (a) is Figure 7 (a) and Figure 7 The three-dimensional view of the retaining unit shown in (b) Figure 8 (b) is Figure 8 (a) shows a partial schematic cross-sectional view of the retaining unit.

[0020] Label Explanation

[0021] 1: Grinding apparatus (processing device); 2: Apparatus housing; 21: Main body; 22: Vertical wall; 3: Holding unit; 32: Chuck table; 320: Frame; 321: Perforated plate; 321a: Adsorption surface; 321b: Side side; 321c: Back side; 322: Upper frame; 322a: Upper surface of the frame; 322b: Plate mounting surface; 322c: Wafer suction hole; 322d: Outer periphery Stepped section; 322e: Bolt hole; 322f: Annular groove; 322g: Lower surface; 322h: Side wall; 323: Lower frame; 323a: Front; 323b: Cooling water passage; 323c: Cooling water supply hole; 323d: Cooling water spray hole; 323e: Through hole; 323f: Bolt hole; 323g: Lower surface; 34: Workbench base; 341: Mounting surface; 34 2: Frame suction hole; 343: Cooling water supply hole; 344: First connecting hole; 345: Bolt fastening hole; 3': Holding unit; 32': Chuck stage; 320': Frame; 322': Upper frame; 322a': Frame upper surface; 322b': Board mounting surface; 322c': Wafer suction hole; 322d': Outer peripheral stepped section; 322e': Bolt hole; 322f' 322g': Annular groove; 322h': Lower surface; 322h': Side wall; 34': Worktable base; 341': Mounting surface; 342': Frame suction hole; 343': Cooling water supply hole; 344': Second connecting hole; 345': Bolt fastening hole; 4: Grinding unit; 5: Processing fluid supply unit; 6a, 6b: Folded cover; 7: Grinding feed mechanism; 8: Bolt; 10: Wafer. Detailed Implementation

[0022] The inventors of this invention conducted an in-depth study on the cause of the slight thickness deviation of the processed wafer. As a result, it was found that in conventional grinding apparatuses, the shape of the frame constituting the chuck stage is slightly different when grinding the holding surface of the chuck stage and when the wafer is attracted and held on the holding surface of the chuck stage for processing. As a result, the thickness deviation of the wafer was found.

[0023] Furthermore, considering both the grinding of the holding surface of the chuck stage and the processing of the wafer by attracting and holding it on the holding surface of the chuck stage, the aforementioned problems can be solved by keeping the shape of the frame constituting the chuck stage as unchanged as possible, thus completing the present invention. Hereinafter, a detailed description of the processing apparatus according to an embodiment of the present invention will be provided with reference to the accompanying drawings.

[0024] exist Figure 1 The figure shows an overall perspective view of a grinding apparatus 1, exemplified as a first embodiment of a processing apparatus constructed according to the present invention. Figure 1 The grinding apparatus 1 shown includes: a holding unit 3, which attracts and holds a plate-shaped wafer 10, which is the workpiece in this embodiment; a grinding unit 4, which is a processing unit, and grinds the holding unit 3 and the wafer 10 attracted and held by the holding unit 3; and a processing fluid supply unit 5, which supplies processing fluid to the wafer 10.

[0025] The grinding apparatus 1 has an apparatus housing 2. The apparatus housing 2 has: a main body 21 in a generally rectangular parallelepiped shape; and an upright wall 22 provided at the rear end of the main body 21 and erected vertically in the vertical direction.

[0026] A holding unit 3 is disposed on the main body 21, and pleated covers 6a and 6b are disposed on both sides of the holding unit 3 in the X-axis direction indicated by arrow X. A moving mechanism (not shown) for moving the holding unit 3 in the X-axis direction is housed inside the main body 21. By operating this moving mechanism, the pleated covers 6a and 6b can be extended and retracted, and the holding unit 3 can be moved between the loading / unloading area near the front of the chuck table 32 where the unprocessed wafer 10 is placed and the processing area on the inner side of the chuck table 32 where processing is performed directly below the grinding unit 4.

[0027] Reference Figure 2 (a) and Figure 2 (b) More specifically, the holding unit 3 of this embodiment is described. The holding unit 3 includes at least: a chuck table 32; and a table base 34 that supports the chuck table 32 for easy loading and unloading. Figure 2As shown in (b), the chuck stage 32 has: a perforated plate 321 having an adsorption surface 321a for adsorbing the wafer 10; and a frame 320 surrounding the adsorption surface 321a of the perforated plate 321, i.e., surrounding the side surface 321b and the back surface 321c located on the opposite side of the adsorption surface 321a. Figure 2 As shown in (b), the frame 320 is decomposed into an upper frame 322 and a lower frame 323. The upper frame 322 is configured to include: an upper surface 322a; a side wall 322h that forms a side surface; a plate mounting surface 322b that mounts the back surface 321c of the porous plate 321; a plurality of wafer attraction holes 322c (two in this embodiment) that are formed to penetrate the plate mounting surface 322b and the lower surface 322g, transmitting attraction force (negative pressure) to the adsorption surface 321a of the porous plate 321; an outer peripheral stepped portion 322d that is formed along the side wall 322h; and a plurality of bolt holes 322e that are formed in the outer peripheral stepped portion 322d for fixing the frame 320 to the worktable base 34. The plurality of wafer attraction holes 322c that open on the plate mounting surface 322b are connected by an annular groove 322f. In this embodiment, four bolt holes 322e are formed at equal intervals on the outer peripheral stepped portion 322d (in Figure 2 (Only 3 are shown in the image). In addition, the lower surface 322g of the upper frame 322 is a flat surface except for the area where the aforementioned wafer attraction hole 322c is formed.

[0028] A cooling water channel 323b formed by a recess of a predetermined depth is formed on the front surface 323a of the lower frame 323. Multiple cooling water supply holes 323c (two in this embodiment) are formed in a predetermined area on the central side of the lower frame 323, extending vertically and supplying cooling water from a cooling water supply source (not shown) to the cooling water channel 323b. Furthermore, in the area of ​​the front surface 323a of the lower frame 323 where the cooling water channel 323b is not formed, corresponding to the wafer attraction hole 322c of the upper frame 322, a through hole 323e is formed vertically to transmit negative pressure. Additionally, in the outer peripheral region of the lower frame 323, bolt holes 323f are formed at positions corresponding to the bolt holes 322e formed in the upper frame 322. The lower surface 323g of the lower frame 323 is formed as a flat surface, except for the areas where the cooling water supply holes 323c, through holes 323e, etc., are formed. The upper frame 322 and the lower frame 323 are joined together to form a single unit, thereby forming a cooling water channel 323b inside the frame 320, and a cooling water spray hole 323d is formed at the outer peripheral end of the cooling water channel 323b. The porous plate 321 of this embodiment is formed, for example, from porous ceramic with air permeability, but it can also be formed from other materials that can be ground and have air permeability, such as aggregates of granular materials made of pumice, resin, or metal, without particular limitation.

[0029] like Figure 2 As shown in (a), the stage base 34 includes at least: a mounting surface 341 that mounts the frame 320; a frame suction hole 342 formed on the mounting surface 341 that transmits negative pressure from a suction source (not shown) to the lower surface 323g of the lower frame 323 constituting the frame 320; a cooling water supply hole 343 that supplies cooling water to the cooling water supply hole 323c of the lower frame 323; and a first connecting hole 344 that communicates with the wafer suction hole 322c formed on the upper frame 322 of the chuck stage 32 and is connected to a suction source (not shown) via a path independent of the frame suction hole 342. In this embodiment, the following are formed on the mounting surface 341: an enlarged diameter portion 342a surrounding the frame suction hole 342; an annular groove 343a connecting a plurality of cooling water supply holes 343; and an annular groove 344a connecting a plurality of first connecting holes 344.

[0030] like Figure 2 As shown in (a), in this embodiment, the frame suction hole 342 is formed in the central region of the mounting surface 341 of the workbench base 34. On the outer periphery of the mounting surface 341 of the workbench base 34, bolt fastening holes 345 are formed at positions corresponding to the bolt holes 322e of the upper frame 322 and the bolt holes 323f of the lower frame 323 of the chuck workbench 32.

[0031] exist Figure 3 The image shows a top view of the lower frame 323. Figure 3 It is understood that the cooling water passage 323b is formed on the entire front surface 323a of the lower frame 323, so that the cooling water supplied through the cooling water supply hole 343 of the worktable base 34 and the cooling water supply hole 323c of the lower frame 323 permeates the entire interior area of ​​the frame 320 and is discharged from the cooling water spray hole 323d. Furthermore, in this embodiment, the frame 320 is constructed by dividing it into an upper frame 322 and a lower frame 323, but the present invention is not limited to this; the frame 320 may also be integrally formed, with the cooling water passage formed inside the frame 320.

[0032] The fastening bolt 8 is inserted into and fastened to the bolt fastening hole 345 of the worktable base 34 through the bolt holes 322e and 323f formed in the frame 320 of the chuck worktable 32, thereby making the chuck worktable 32 and the worktable base 34 a single unit.

[0033] exist Figure 4 (a) shows the retaining unit 3 (refer to) on which the chuck table 32 is placed on the table base 34 and is integrally formed by bolts 8. Figure 2 The 3D diagram, in Figure 4 (b) shows the method used for... Figure 4A partial schematic cross-sectional view illustrating the internal structure of retaining unit 3, shown in (a). Additionally, Figure 4 (b) is not Figure 4 The actual cross-sectional view of retaining unit 3 shown in (a) is also included for ease of explanation, showing multiple paths that actually appear in different cross-sections.

[0034] like Figure 4 As shown in (b), the stage base 34 has a first attraction path 346 that transmits attraction force to the frame attraction hole 342 formed on the mounting surface 341 of the mounting frame 320. By activating the attraction source (not shown), even when the wafer 10 is not held on the holding unit 3, the lower surface 323g of the lower frame 323 constituting the holding unit 320 can be attracted by the first attraction force (negative pressure) Vm1. In addition, when the wafer 10 is placed on the adsorption surface 321a of the porous plate 321 for attraction and holding, the second attraction force (negative pressure) Vm2 can be transmitted to the adsorption surface 321a of the porous plate 321 through the first connecting hole 344 formed on the stage base 34, the through hole 323e of the lower frame 323, and the wafer attraction hole 322c of the upper frame 322 to attract and hold the wafer 10. Furthermore, the frame suction hole 342 and the first connecting hole 344 are connected to a suction source (not shown) via independent suction paths, so that even if the wafer 10 is not attracted and held on the chuck stage 32, the frame 320 can be attracted and held simply by being pulled toward the stage base 34.

[0035] return Figure 1 Continuing the description, the grinding unit 4 is disposed on the front surface of the vertical wall 22. The grinding unit 4 has a movable base 41 and a spindle unit 42 mounted on the movable base 41. The movable base 41 engages with a pair of guide rails 221, 221 disposed on the vertical wall 22 of the device housing 2 on its rear surface side, so as to be able to slide relative to the guide rails 221, 221 in the Z-axis direction (vertical direction).

[0036] The spindle unit 42 includes: a spindle housing 421 supported on a support portion 413 integrally formed with a movable base 41; a rotary spindle 422 rotatably held in the spindle housing 421; and a servo motor 423, which is provided as a rotary drive unit for rotating the rotary spindle 422. The lower end of the rotary spindle 422 protrudes towards the lower end of the spindle housing 421, and a mounting base 424 is provided at the lower end of the rotary spindle 422. A grinding wheel 425 is mounted on the lower surface of the mounting base 424, and a plurality of grinding tools 426 (see also) are arranged in a ring on the lower surface of the grinding wheel 425. Figure 5 ).

[0037] Figure 1 The grinding apparatus 1 shown has a grinding feed mechanism 7 that moves the grinding unit 4 along the pair of guide rails 221, 221 in a vertical direction (perpendicular to the holding surface of the chuck table described later). This grinding feed mechanism 7 has an externally threaded rod 71 disposed on the front surface of the vertical wall 22 and extending in the vertical direction. The upper and lower ends of the externally threaded rod 71 are rotatably supported on the vertical wall 22. A pulse motor 72, serving as a drive source for rotating the externally threaded rod 71, is disposed at the upper end of the externally threaded rod 71, and the output shaft of the pulse motor 72 is connected to the externally threaded rod 71. A threaded connection portion (not shown) is formed on the rear surface of the movable base 41, and an internally threaded hole extending in the vertical direction is formed in this connection portion, in which the externally threaded rod 71 is screwed. Such a grinding feed mechanism 7 can cause the pulse motor 72 to rotate forward so that the grinding unit 4 and the moving base 41 can descend together, and cause the pulse motor 74 to rotate in reverse so that the grinding unit 4 and the moving base 41 can rise together.

[0038] The grinding apparatus 1 is equipped with a machining fluid supply unit 5 that supplies grinding fluid L, such as grinding water, to the workpiece being ground on the holding unit 3. The machining fluid supply unit 5 includes: a machining fluid container 51 that stores the machining fluid L and has a pressure pump; a machining fluid supply path 52 that connects the machining fluid container 51 and the grinding unit 4; and an on / off valve 53 disposed on the machining fluid supply path 52 for opening and closing the machining fluid supply path 52. By activating the pressure pump of the machining fluid container 51 and opening the on / off valve 53, the machining fluid L can be supplied to the processing area via the grinding unit 4.

[0039] The grinding apparatus 1 of this embodiment has a structure generally as described above, and its functions and effects will be explained below.

[0040] As described above, when grinding the wafer 10 in the grinding apparatus 1, before processing the wafer 10, such as... Figure 5 As shown, the holding surface of the chuck table 32, i.e., the suction surface 321a of the perforated plate 321, is ground by the grinding unit 4. During this grinding process, firstly, according to... Figure 4 As explained in (b), the attraction source (not shown) is activated, thereby applying a first attraction force (negative pressure) Vm1 to the lower surface 323g of the lower frame 323 constituting the frame 320, attracting and holding the frame 320. At this time, the wafer 10 is not placed on the adsorption surface 321a of the chuck stage 32, so the second attraction force (negative pressure) Vm2 does not need to be transmitted through the first connecting hole 344 formed in the stage base 34 and the wafer attraction hole 322c and through hole 323e of the frame 320.

[0041] Next, the moving mechanism (not shown) is activated to position the chuck table 32 in the machining area below the grinding unit 4, i.e., as shown... Figure 5 The grinding wheel 426, positioned in the grinding unit 4, is located at the rotation center of the chuck table 32. Next, the spindle 422 of the grinding unit 4 is rotated at a predetermined speed (e.g., 4000 rpm) in the direction indicated by arrow R1, and a rotary drive unit (not shown) is activated to rotate the chuck table 32 at a predetermined speed (e.g., 300 rpm) in the direction indicated by arrow R2. At this time, the aforementioned cooling water supply source is activated, supplying cooling water W to the cooling water passage 323b formed inside the frame 320 via the cooling water supply hole 343 of the table base 34.

[0042] Next, the grinding feed mechanism 7 is activated, causing the grinding unit 4 to descend in the direction indicated by arrow R3. While supplying the machining fluid L (grinding water) to the adsorption surface 321a of the chuck table 32, the grinding tool 426, disposed on the lower surface of the grinding wheel 425, comes into contact with the perforated plate 321 of the chuck table 32, grinding the adsorption surface 321a of the perforated plate 321 at a predetermined descent speed (e.g., 0.1 μm / s). During this grinding process, the cooling water supply source continues to operate, and the cooling water W flows within the cooling water passage 323b formed inside the frame 320 and is discharged from the cooling water spray hole 323d, cooling the frame 320 to a predetermined temperature. Furthermore, if the holding surface of the chuck stage 32, namely the suction surface 321a of the perforated plate 321, and the upper frame surface 322a of the upper frame 322, are ground during a predetermined time or amount of grinding, the grinding feed mechanism 7 is stopped, and then idled for a predetermined time to complete the grinding process. Additionally, the processing fluid L supplied to the holding surface of the chuck stage 32 can be provided using the aforementioned processing fluid supply unit 5, and can be ejected from the suction surface 321a of the perforated plate 321 via the wafer suction hole 322c.

[0043] After grinding the suction surface 321a of the chuck table 32 as described above, as Figure 6 As shown, grinding is performed on the wafer 10. Furthermore, the grinding of the suction surface 321a of the chuck stage 32 is not performed every time the wafer 10 is ground, but rather approximately once a day, for example. As shown on the left side of the figure, the wafer 10 is divided by predetermined dividing lines 14, and multiple devices 12 are formed on its front side 10a. A protective tape T is attached to the front side 10a of the wafer 10 to form a single unit. The wafer 10 is flipped so that its back side 10b faces upward and the protective tape T faces downward, and placed on the chuck stage 32, which is moved to the loading / unloading area.

[0044] When performing grinding on the back surface 10b of wafer 10, firstly according to... Figure 4 As explained in (b), the attraction source (not shown) is activated, thereby applying a first attraction force (negative pressure) Vm1 to the lower surface 323g of the lower frame 323 of the frame 320, attracting and holding the frame 320. Additionally, a second attraction force (negative pressure) Vm2 is transmitted to the adsorption surface 321a of the porous plate 321 via the first connecting hole 344 formed in the stage base 34 and the wafer attraction hole 322c in the upper frame 322, attracting and holding the wafer 10 on the adsorption surface 321a of the chuck stage 32.

[0045] Next, the moving mechanism (not shown) is activated to position the chuck table 32 in the processing area below the grinding unit 4, specifically at the rotation center of the chuck table 32, which is held by the grinding wheel 426 of the grinding unit 4 by attraction. Then, the spindle 422 of the grinding unit 4 is rotated at a predetermined speed (e.g., 4000 rpm) in the direction indicated by arrow R4, and the rotation drive unit (not shown) is activated to rotate the chuck table 32 at a predetermined speed (e.g., 300 rpm) in the direction indicated by arrow R5. At this time, the cooling water supply source is activated, supplying cooling water W to the cooling water passage 323b formed inside the frame 320 via the cooling water supply hole 343 of the table base 34. Next, while operating the processing fluid supply unit 5, processing fluid L (grinding water) is supplied, and the grinding feed mechanism 7 is activated. The grinding unit 4 descends in the direction indicated by arrow R6 at a predetermined descent speed (e.g., 0.1 μm / s), bringing the grinding wheel 426 into contact with the back surface 10b of the wafer 10. While the thickness of the wafer 10 is detected by a thickness detection unit (not shown), grinding is performed to the desired thickness. During this grinding process, the cooling water supply source continues to operate, and cooling water W flows within the cooling water channel 323b formed inside the frame 320 and exits from the cooling water nozzle 323d, cooling the frame 320 to a predetermined temperature. Once this grinding has been performed, the grinding feed mechanism 7 is stopped, and the grinding process is complete.

[0046] According to the above embodiment, in any case, whether grinding the adsorption surface 321a of the perforated plate 321 of the chuck stage 32 or grinding the wafer 10, the entire area of ​​the frame 320 of the chuck stage 32 is reliably fixed on the stage base 34, and grinding by the grinding wheel 425 of the grinding unit 4 is performed while maintaining a predetermined temperature by cooling water W. Therefore, the shape of the holding surface of the chuck stage 32 is substantially consistent with the shape of the grinding surface of the wafer 10, which can suppress thickness deviations of the wafer 10 after grinding.

[0047] Furthermore, in the above embodiment, the wafer attraction hole 322c that transmits the attraction force to the adsorption surface 321a of the perforated plate 321 constituting the holding surface of the chuck stage 32 and the frame attraction hole 342 that attracts and holds the frame 320 of the chuck stage 32 to the mounting surface 341 of the stage base 34 are formed independently. Therefore, it is possible to prevent the processing fluid L mixed with grinding chips attracted from the perforated plate 321 of the chuck stage 32 from entering between the mounting surface 341 of the stage base 34 and the frame 320, and it is also possible to suppress the thickness deviation of the wafer 10 caused by the grinding chips.

[0048] Furthermore, after grinding the back surface 10b of the wafer 10, a mixture of air and water is supplied to the perforated plate 321 and ejected through the wafer suction hole 322c. When the wafer 10 is removed from the chuck stage 32, the processing fluid L mixed with grinding chips that has entered the wafer suction hole 322c can also be ejected. However, since the wafer suction hole 322c is independent of the frame suction hole 342, it is possible to prevent the processing fluid L mixed with grinding chips from entering between the mounting surface 341 of the stage base 34 and the frame 320. Similarly, the thickness deviation of the wafer 10 caused by the grinding chips can also be suppressed. In addition, even if the above processing apparatus is an apparatus that uses free abrasive particles to perform wafer grinding, it is possible to prevent free abrasive particles from reaching the mounting surface 341 of the stage base 34, and the thickness deviation of the wafer caused by free abrasive particles can also be suppressed. Furthermore, a cooling water channel 323b is formed inside the frame 320, thereby maintaining the chuck stage 32 at a specified temperature through the cooling water W, thereby suppressing the thermal expansion of the frame 320 and also suppressing the thickness deviation of the wafer 10.

[0049] Furthermore, the present invention is not limited to the processing apparatus of the first embodiment described above, but may also be the second embodiment described below. Additionally, reference is made below. Figure 7 of (a), Figure 7 (b) Figure 8 (a) and Figure 8 The second embodiment described in (b) is relative to the one based on Figure 1 The grinding apparatus 1 of the first embodiment described herein differs only in the structure of the retaining unit 3'. Therefore, the description of the grinding apparatus 1 as a whole is omitted, and the same reference numerals are used for structures that are the same as those of the retaining unit 3 described previously, and the description of such structures is omitted as appropriate.

[0050] like Figure 7 (a) and Figure 7 As shown in (b), the retaining unit 3' includes at least: a chuck table 32'; and a table base 34' that supports the chuck table 32' for easy loading and unloading. Figure 7As shown in (b), the chuck stage 32' has: a perforated plate 321 having an adsorption surface 321a for adsorbing the wafer 10; and a frame 320' surrounding the adsorption surface 321a of the perforated plate 321, i.e., surrounding the side surface 321b and the back surface 321c located on the opposite side of the adsorption surface 321a. Figure 7 As shown in (b), the frame 320' of this embodiment is decomposed into an upper frame 322' and a lower frame 323. Furthermore, the structure of the lower frame 323 in this embodiment is the same as that of the lower frame 323 used in the previously described embodiment. The upper frame 322' has an upper surface 322a' and is configured to include: a sidewall 322h' forming a side surface; a plurality of wafer attraction holes 322c' formed on the sidewall 322h' to transmit attraction force (negative pressure) to the adsorption surface 321a of the porous plate 321; an outer peripheral stepped portion 322d' formed along the sidewall 322h'; and a plurality of bolt holes 322e' formed on the outer peripheral stepped portion 322d' for fixing the frame 320' to the worktable base 34'.

[0051] In the upper frame 322', two vertical straight grooves 322f' are formed on the plate mounting surface 322b' of the back surface 321c of the perforated plate 321, which connect the four wafer attraction holes 322c' formed on the side wall 322h' of the upper frame 322'. In addition, the lower surface 322g' of the upper frame 322' is a flat surface.

[0052] like Figure 7 As shown in (a), the workbench base 34' includes at least: a mounting surface 341', which mounts the lower surface 323g of the frame 320' opposite to the mounting surface 322b' of the perforated plate 321; a frame suction hole 342', which, by actuating a suction source (not shown), attracts and holds the lower surface 323g of the lower frame 323 constituting the frame 320'; and a cooling water supply hole 343', which supplies cooling water to... Figure 7 (b) shows a cooling water supply hole 323c in the lower frame 323 that provides cooling water; and a second connecting hole 344' formed on the side of the stage base 34', communicating with a wafer suction hole 322c' formed in the upper frame 322', and connected to a suction source (not shown) via a path independent of the aforementioned frame suction hole 342'. In this embodiment, the stage base 34' has the following on its mounting surface 341': an enlarged diameter portion 342a' surrounding the frame suction hole 342'; and an annular groove 343a' that connects the plurality of cooling water supply holes 343' in an annular shape.

[0053] In this embodiment, the frame suction hole 342' is formed in the central region of the mounting surface 341' of the workbench base 34'. On the outer periphery of the mounting surface 341', a bolt fastening hole 345' is formed at a position corresponding to the bolt hole 322e' formed in the frame 320' of the chuck workbench 32'. Furthermore, in Figure 7 (a) and Figure 7 Based on (b) Figure 8 (a) can be understood that the fastening bolt 8 is inserted and fastened into the bolt fastening hole 345' formed on the mounting surface 341' of the worktable base 34' through the bolt hole 322e' formed on the frame 322' of the chuck worktable 32', thereby making the chuck worktable 32' and the worktable base 34' an integral unit, and the wafer suction hole 322c' and the second connecting hole 344' are connected through the connecting passage 346.

[0054] Additionally, refer to the partial schematic cross-sectional view showing the retaining unit 3'. Figure 8 As can be understood from (b), the second connecting hole 344' is connected to an attraction source (not shown) via a separate path relative to the aforementioned frame attraction hole 342'. Furthermore, to illustrate the connecting structure of the connecting path 346, Figure 8 The partial schematic cross-sectional view shown in (b) combines the views with... Figure 4 (b) Cross-sections at different locations.

[0055] according to Figure 7 of (a), Figure 7 (b) Figure 8 (a) and Figure 8 As shown in (b) as the holding unit 3' in the second embodiment, the stage base 34' has a frame attraction hole 342' formed on the mounting surface 341' of the lower surface 323g of the mounting frame 320'. Therefore, by activating the attraction source (not shown), a first attraction force (negative pressure) Vm1 can be applied to the lower surface 323g of the frame 320', attracting and holding the frame 320'. In addition, when the wafer 10 is placed on the adsorption surface 321a of the porous plate 321 for attraction and holding, the second attraction force (negative pressure) Vm2 is transmitted to the adsorption surface 321a of the porous plate 321 through the second connecting hole 344', the connecting path 346 and the wafer attraction hole 322c' formed in the stage base 34', which can attract and hold the wafer 10. Additionally, the cooling water supply source (not shown in the diagram) can be activated to supply cooling water W to the cooling water passage 323b formed inside the frame 320' via the cooling water supply hole 343' of the worktable base 34'.

[0056] exist Figure 7 of (a), Figure 7 (b) Figure 8 (a) and Figure 8 In the second embodiment shown in (b), the frame suction hole 342' and the second connecting hole 344' are connected to the suction source via independent suction paths, and a cooling water channel 323b is provided inside the frame 320', thus enabling it to function as described in the figure. Figure 2 of (a), Figure 2 (b) Figure 3 , Figure 4 (a) and Figure 4 The holding unit 3 described in (b) has the same effect as the first embodiment. In addition, according to this embodiment, the attraction force Vm2 transmitted to the adsorption surface 321a of the porous plate 321 held by the frame 322' is not provided by the mounting surface 341' of the worktable base 34' but through the wafer attraction hole 322c', the connecting path 346 and the second connecting hole 344' formed in the side wall 322h' of the frame 322'. Therefore, the problem of the processing fluid L mixed with grinding chips entering between the mounting surface 341' of the worktable base 34' and the frame 320' is more reliably avoided, and the thickness deviation of the wafer 10 caused by the grinding chips is further suppressed.

Claims

1. A processing apparatus, wherein, The processing apparatus includes: Holding unit, which attracts and holds the wafer; The processing unit has a grinding wheel for grinding the wafer held by the holding unit, and the grinding wheel is rotatable; and The processing fluid supply unit supplies processing fluid to the wafer. The holding unit has: A chuck stage that holds the wafer; and The worktable base supports the chuck worktable for easy loading and unloading. The chuck table has the following features: A porous plate having an adsorption surface for adsorbing wafers; A frame surrounding the adsorption surface; Cooling water channels are formed inside the frame and allow cooling water to permeate the space. A wafer attraction hole, formed in the frame, transmits an attractive force to the attraction surface of the porous plate; and Bolt holes, formed in the frame, secure the chuck worktable to the worktable base. The workbench base has the following features: The mounting surface is placed on the lower surface side of the frame; A frame suction hole, formed on the mounting surface, attracts and holds the frame; and A cooling water supply port, which communicates with the cooling water passage, supplies cooling water to the cooling water passage. The wafer attraction hole is formed on the plate mounting surface of the frame for mounting the porous plate. A connecting hole is formed on the mounting surface of the worktable base. The connecting hole communicates with the wafer attraction hole to attract and hold the wafer using a second attraction force. The frame attraction hole attracts and holds the frame using a first attraction force. The connecting hole for attracting the wafer transmits the attraction force independently of the frame attraction hole for attracting the frame. When no wafer is placed on the suction surface of the chuck stage, a second attraction force for attracting and holding the wafer is not generated through the connecting hole and the wafer attraction hole, but a first attraction force for attracting and holding the frame is generated through the frame attraction hole.

2. A processing apparatus, wherein, The processing apparatus includes: Holding unit, which attracts and holds the wafer; The processing unit has a grinding wheel for grinding the wafer held by the holding unit, and the grinding wheel is rotatable; and The processing fluid supply unit supplies processing fluid to the wafer. The holding unit has: A chuck stage that holds the wafer; and The worktable base supports the chuck worktable for easy loading and unloading. The chuck table has the following features: A porous plate having an adsorption surface for adsorbing wafers; A frame surrounding the adsorption surface; Cooling water channels are formed inside the frame and allow cooling water to permeate the space. A wafer attraction hole, formed in the frame, transmits an attractive force to the attraction surface of the porous plate; and Bolt holes, formed in the frame, secure the chuck worktable to the worktable base. The workbench base has: The mounting surface is placed on the lower surface side of the frame; A frame suction hole, formed on the mounting surface, attracts and holds the frame; and A cooling water supply port, which communicates with the cooling water passage, supplies cooling water to the cooling water passage. The chip suction hole is formed on the side of the frame. A connecting hole is formed on the side of the worktable base, which communicates with the wafer attraction hole and transmits attraction independently relative to the frame attraction hole.

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