attachment

Abstract

This invention provides an attachment for use with a processing device that planes a workpiece to a desired thickness. [Solution] The attachment 37 applied to the processing apparatus 1 that plane-machines a non-circular workpiece W with a grinding wheel 21 is detachably provided on the outer circumference side of the suction body 33 of the chuck table 31 that houses the suction body 33 capable of holding the workpiece W by suction. Furthermore, the attachment 37 is made of a material that is more difficult to machine than the suction body 33, is capable of contacting the grinding wheel 21 during self-grinding to grind the suction body 33, and is provided on the outer circumference side of the suction body 33 in a region where the machining pressure at which the grinding wheel 21 grinds the workpiece W is relatively low during plane machining of the workpiece W.

Description

Technical Field

[0005]

[0001] The present invention relates to an attachment applied to a processing apparatus for planar processing of a workpiece.

Background Art

[0002] In the semiconductor manufacturing field, a processing apparatus for thinly and flatly planar processing of a semiconductor workpiece such as a silicon wafer (hereinafter referred to as "workpiece") is known.

[0003] Patent Document 1 discloses a grinding apparatus that contacts a rotating grindstone with the upper surface of a rectangular workpiece held on a chuck table and grinds the rectangular workpiece to a predetermined thickness.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when planar processing a workpiece, due to the influence of the fixing surface accuracy of the workpiece and the mounting accuracy of processing tools such as grindstones, there is a risk of thickness variation occurring in the processed workpiece. In order to eliminate such thickness variation, conventionally, it has been necessary to reassemble or adjust the fixing surface of the workpiece and the processing tool.

[0006] Furthermore, when infeed machining workpieces with shapes other than circular or workpieces with orientation flats (hereinafter collectively referred to as "non-circular workpieces"), the contact area between the grinding wheel and the workpiece is not constant for each predetermined rotation of the chuck table. In areas with a relatively large contact area, the amount of material removed from the workpiece tends to be small, while in areas with a relatively small contact area, the amount of material removed tends to be large. In other words, the thickness of the workpiece varies depending on the size of the contact area between the grinding wheel and the workpiece during machining, resulting in the problem that the workpiece cannot be finished to the desired thickness.

[0007] Therefore, a technical challenge arises in order to machine a workpiece to a desired thickness, and the present invention aims to solve this challenge. [Means for solving the problem]

[0008] To achieve the above objective, the attachment according to the present invention is an attachment applied to a processing apparatus for planar machining a non-circular workpiece with a grinding wheel, and is detachably provided on the outer circumference side of a chuck table that houses a suction body capable of holding the workpiece by suction, is made of a material that is more difficult to machine than the suction body, is capable of contacting the grinding wheel during self-grinding to grind the suction body, and is provided on the outer circumference side of the suction body in a region where the machining pressure at which the grinding wheel grinds the workpiece during planar machining is relatively low.

[0009] Furthermore, in order to achieve the above objective, the attachment according to the present invention is an attachment applied to a processing apparatus for planar machining of a non-circular workpiece with a grinding wheel, and is detachably provided on the outer circumference side of a chuck table that houses a rectangular suction body capable of holding the workpiece by suction, is made of a material that is more difficult to machine than the suction body, is capable of contacting the grinding wheel during self-grinding to grind the suction body, and is provided on the outer circumference side of the four corners of the suction body. [Effects of the Invention]

[0010] This invention can reduce variations in the thickness of a workpiece after planar machining, which are caused by the shape of the workpiece. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic diagram showing a processing apparatus relating to one embodiment of the present invention. [Figure 2] A perspective view showing a chuck table. [Figure 3] Figure 2 shows the chuck table, where (a) is a plan view and (b) is a cross-sectional view of AA within (a). [Figure 4] A schematic diagram illustrating the process of self-grinding. [Figure 5] A plan view comparing the contact area between the workpiece and the grinding wheel at two locations within the workpiece. [Figure 6] Schematic diagram showing the thickness of the workpiece after planar machining at two locations, as shown in Figure 5. [Figure 7] A plan view showing the positional relationship of the attachment to the adsorbent. [Figure 8] (a) is a schematic diagram showing the thickness after self-grinding at two locations within the adsorbent body, and (b) is a schematic diagram showing the thickness after planar machining at two locations within the workpiece. [Figure 9] A perspective view showing a chuck table applied to a processing apparatus according to a modified example of the present invention. [Figure 10] Figure 9 shows the chuck table, where (a) is a plan view and (b) is a cross-sectional view of the BB in (a). [Modes for carrying out the invention]

[0012] One embodiment of the present invention will be described with reference to the drawings. In the following, when referring to the number, numerical values, quantities, ranges, etc., of components, unless specifically indicated or clearly limited to a particular number in principle, the number is not limited to that particular number and may be greater than or less than that number.

[0013] In addition, when referring to the shape, positional relationship, etc. of components, etc., unless otherwise specifically stated or it is considered not to be so clearly in principle, it includes those that are substantially approximated or similar to the shape, etc.

[0014] In addition, the drawings may be exaggerated, such as by enlarging characteristic parts to make the features easier to understand, and the dimensional ratios of components, etc. are not necessarily the same as in reality. Also, in sectional views, in order to make the sectional structure of components easier to understand, the hatching of some components may be omitted.

[0015] In addition, in this embodiment, expressions indicating directions such as up and down, left and right, etc. are not absolute. They are appropriate when each component is in the posture depicted in the drawing, but when the posture changes, they should be interpreted as being changed according to the change in posture.

[0016] The machining device 1 performs grinding on the workpiece W. As shown in FIG. 1, the machining device 1 includes a machining unit 2 and a holding unit 3.

[0017] The machining unit 2 includes a grindstone 21, a grindstone spindle 22, and an infeed mechanism 23.

[0018] The grindstone 21 is, for example, a cup-shaped grindstone and is attached to the lower end of the grindstone spindle 22.

[0019] The grindstone spindle 22 is rotatable around the rotation axis 2a, and the grindstone 21 and the grindstone spindle 22 are configured to be integrally rotatable.

[0020] The infeed mechanism 23 raises and lowers the grindstone spindle 22 in the vertical direction. The infeed mechanism 23 has a known configuration and is, for example, composed of a plurality of linear guides for guiding the moving direction of the grindstone spindle 22 and a ball screw slider mechanism for raising and lowering the grindstone spindle 22. The infeed mechanism 23 is interposed between the grindstone spindle 22 and the column 24.

[0021] The holding unit 3 comprises a chuck table 31 and a chuck spindle 32.

[0022] The chuck table 31 is equipped with an adsorbent 33 made of a porous material such as alumina on its upper surface, and a dense body 34 in which the adsorbent 33 is embedded approximately in the center.

[0023] The chuck table 31 is equipped with a conduit (not shown) that runs through its interior and extends to its surface. The conduit is connected to a vacuum source, a compressed air source, or a water source via a rotary joint (not shown). When the vacuum source is activated, a negative pressure is created between the workpiece W placed on the adsorbent body 33 and the upper surface (adsorption surface 33a) of the adsorbent body 33, causing the workpiece W to be adsorbed and held by the adsorption surface 33a. When the compressed air source or water source is activated, the adsorption between the workpiece W and the adsorbent body 33 is released.

[0024] The adsorbent 33 is formed in a shape corresponding to the rectangular workpiece W when viewed from a plane.

[0025] The chuck spindle 32 is configured to rotate the chuck table 31 around the rotation axis 3a. The drive source for the chuck spindle 32 could be, for example, a servo motor.

[0026] As shown in Figure 2, the chuck table 31 has an annular recess 35 formed around the suction body 33. Multiple bolt holes 36 are formed at the bottom of the annular recess 35. Note that the annular recess 35 does not need to be formed around the entire circumference of the suction body 33, but may be formed locally in the area where the attachment 37 described later can be attached.

[0027] An attachment 37 is mounted in the annular recess 35. Specifically, as shown in Figure 3(a), the attachment 37 is positioned to block the space between the four corners of the suction body 33 and the outer edge of the chuck table 31, along the radial direction of the chuck table 31 when viewed from above. The attachment 37 can be made of a hard-to-machine material with higher hardness than the suction body 33, for example, the same material as the dense body 34. Also, as shown in Figure 3(b), when the attachment 37 is mounted on the chuck table 31, the suction surface 33a and the upper surface (contact surface 37a) of the attachment 37 are substantially flush.

[0028] The attachment 37 has a bolt hole 38 formed through its top and bottom. The attachment 37 is detachably fastened to the chuck table 31 via a bolt 39. Preferably, the corners of the contact surface 37a are chamfered to suppress chipping by the grinding wheel 21.

[0029] The operation of the processing apparatus 1 is controlled by a control unit (not shown). The control unit controls each of the components that make up the processing apparatus 1. The control unit is composed of, for example, a CPU, memory, etc. The functions of the control unit may be realized by control using software or by operation using hardware.

[0030] Next, the self-grinding function of processing device 1 will be explained based on the drawings.

[0031] Self-grinding, as shown in Figure 4, is a process in which the grinding wheel 21 is brought close to the chuck table 31 by the infeed mechanism 23, and the suction surface 33a of the suction body 33 is ground with the grinding wheel 21. Self-grinding is performed as needed to maintain the suction surface 33a in the desired shape, and is generally performed prior to the planar machining of the workpiece W when the chuck table 31 is replaced.

[0032] When the processing device 1 performs planar machining on a non-circular workpiece W by bringing the machining surface of the grinding wheel 21 into parallel contact with the workpiece W, the amount of material removed (grinding amount) of the workpiece W may not be stable within the plane. The reason for this will be explained below with reference to Figure 5. In the following explanation, a square-shaped workpiece W in plan view will be used as an example, but the shape of the workpiece W is not limited to this.

[0033] As shown in Figure 5, when comparing the contact area A1 between the workpiece W and the grinding wheel 21 when the machining surface of the grinding wheel 21 contacts the workpiece W so as to pass through the corner of the workpiece W and the rotation center O of the chuck table 31, with the contact area A2 between the workpiece W and the grinding wheel 21 when the machining surface of the grinding wheel 21 contacts the workpiece W so as to pass through the center of the edge of the workpiece W and the rotation center O, it can be seen that the contact area A1 is about twice as wide as the contact area A2.

[0034] When the grinding wheel 21 is brought into uniform contact with the entire surface of the workpiece W, as the contact area between the workpiece W and the grinding wheel 21 increases, the amount of grinding removed from the workpiece W decreases, and the workpiece W becomes thicker after processing. In other words, comparing the thickness of the workpiece W after grinding in contact areas A1 and A2, as shown in Figure 6, the workpiece W in contact area A2 is formed to be thicker than the workpiece W in contact area A1. For example, in the case of a 280 mm square workpiece W, the end P2 of contact area A2 is ground to be about 4 μm thinner than the end P1 of contact area A1.

[0035] Therefore, in the processing device 1, the amount of self-grinding is locally increased or decreased within the adsorbent 33 in order to counteract the change in the thickness of the workpiece W that corresponds to the change in the contact area between the workpiece W and the grinding wheel 21 during planar machining.

[0036] Specifically, as shown in Figure 7, a first machining region R1 in which the amount of grinding of the workpiece W is relatively small and a second machining region R2 in which the amount of grinding of the workpiece W is relatively large are assumed, and an attachment 37 is placed on the outer circumference of the adsorbent 33 in the first machining region R1.

[0037] In this embodiment, the first processing area R1 is set in a sector shape with a central angle of ±15 degrees centered on the diagonal of the adsorbent 33, and the second processing area R2 is set in a roughly sector shape with a central angle of 60 degrees between adjacent first processing areas R1. The size of each processing area R1 and R2 may be appropriately changed according to the processing conditions of the workpiece W.

[0038] Furthermore, because the attachment 37 is made of a more difficult-to-machine material than the adsorbent 33, as shown in Figure 8(a), the amount of grinding of the adsorbent 33 in the first machining region R1 during self-grinding is less than the amount of grinding of the adsorbent 33 in the second machining region R2, so that the adsorbent 33 in the first machining region R1 is locally ground thicker.

[0039] Then, when the workpiece W is machined on a flat surface, as shown in Figure 8(b), the amount of grinding removed from the workpiece W in the first machining area R1 during flat surface machining is less than the amount of grinding removed from the workpiece W in the second machining area R2. Therefore, the workpiece W in the first machining area R1 is machined to be thicker than the workpiece W in the second machining area R2.

[0040] In this way, the difference in the amount of grinding between the first machining area R1 and the second machining area R2 during planar machining is offset by the difference in thickness between the first machining area R1 and the second machining area R2 within the adsorbent 33, thereby reducing the thickness variation of the workpiece W after planar machining.

[0041] Furthermore, the suction body 33 and attachment 37 are not limited to the shapes described above. For example, when the chuck table 31 suctions and holds a workpiece W on which an orientation flat OF has been formed, the suction body 33 may be formed in a circular shape when viewed from above, and the attachment 37 may be formed in an annular fan shape when viewed from above, as shown in Figures 9, 10(a), and (b).

[0042] In this manner, the processing apparatus 1 according to this embodiment is a processing apparatus 1 for planar machining of a workpiece W with a grinding wheel 21, and comprises a suction body 33 capable of adsorbing and holding the workpiece W, and an attachment 37 provided on the outer circumference of the suction body 33, made of a material that is more difficult to machine than the suction body 33, and capable of contacting the grinding wheel 21 during self-grinding to grind the suction body 33.

[0043] With this configuration, when the grinding wheel 21 performs planar machining on the workpiece W, the thickness of the adsorbent 33 after self-grinding in the first machining region R1 where the grinding wheel 21 contacts the adsorbent 33 and attachment 37 becomes thicker than the thickness of the adsorbent 33 after self-grinding in the second machining region R2 where the grinding wheel 21 contacts the adsorbent 33, thereby reducing variations in the thickness of the workpiece W after planar machining. This is achieved by offsetting the variation in the thickness of the workpiece W after planar machining.

[0044] Furthermore, in this embodiment, the processing apparatus 1 is configured such that the attachment 37 is detachably provided on the chuck table 31 that houses the suction body 33.

[0045] With this configuration, the position of the attachment 37 relative to the adsorbent 33 can be changed, so the shape of the adsorbent 33 after self-grinding can be changed according to the shape of the workpiece W and the processing conditions.

[0046] Furthermore, the processing apparatus 1 according to this embodiment is configured such that the workpiece W is formed in a non-circular shape.

[0047] This configuration makes it possible to reduce variations in the thickness of the workpiece W after planar machining, which can be caused by the shape of the workpiece W.

[0048] Furthermore, the present invention can be modified in various ways other than those described above, as long as it does not depart from the spirit of the invention, and it goes without saying that the present invention extends to such modifications. In addition, the embodiments and modifications described above may be combined with each other. [Explanation of Symbols]

[0049] 1: Processing equipment 2: Processing section 21: Sharpening stone 22: Grinding wheel spindle 23: Infeed mechanism 24: Column 3: Holding part 31: Chuck Table 32: Chuck Spindle 33: Adsorbent 33a: Adsorption surface 34 : Dense body 35: Annular recess 36: Bolt hole (in a dense material) 37: Attachment 37a: Contact surface 38: Bolt holes (of the attachment) 39: Bolt R1: First machining area R2: Second machining area W: Work

Claims

1. An attachment applied to a processing device that performs planar machining on a non-circular workpiece using a grinding wheel, A chuck table containing an adsorbent capable of adsorbing and holding the workpiece is provided, detachably attached to the outer circumference of the adsorbent, The adsorbent is made of a difficult-to-machine material, The adsorbent is capable of contacting the grinding wheel during self-grinding, An attachment provided on the outer circumference of the adsorbent body in a region where the machining pressure at which the grinding wheel grinds the workpiece during planar machining of the workpiece is relatively low.

2. An attachment applied to a processing device that performs planar machining on a non-circular workpiece using a grinding wheel, A chuck table that houses a rectangularly shaped adsorbent capable of adsorbing and holding the aforementioned workpiece is provided, detachably on the outer circumference side of the adsorbent, The adsorbent is made of a difficult-to-machine material, The adsorbent is capable of contacting the grinding wheel during self-grinding, Attachments provided on the outer circumference of the four corners of the aforementioned adsorbent.

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