Truer molding method

Abstract

To provide a truer molding method that achieves reduction in time and cost required for formation of a truer and quality homogenization, and improves a trueing transfer rate, processability, and accuracy of a groove formed in the truer, in particular, further improves accuracy of an edge shape of the truer.SOLUTION: A truer molding method in trueing for forming a groove in a grindstone for grinding a chamfer part of a wafer by a disk-like truer includes: a process A in which a diameter and a rough shape of the truer are adjusted by a master grindstone for molding the truer; and a process B in which an edge of the truer is molded into a target shape. The process A and the process B are performed by use of each of a plurality of master grooves which have different shapes and are formed in the master grindstone, or the process A and the process B are performed by use of each of portions with different shapes in at least one master groove which is formed in the master grindstone.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to truing of a high-precision chamfering device on the end faces of various materials such as silicon, sapphire, compounds, and glass, particularly plate-shaped workpieces such as semiconductor wafers and glass panels, and to a truer forming method in truing to form processing grooves in a grinding wheel that chamfer-grinds plate-shaped workpieces. [Background technology]

[0002] Conventionally, chamfer grinding of plate-shaped workpieces such as semiconductor wafers is performed by pressing a grinding wheel against the outer periphery of the plate-shaped workpiece. Typically, a groove having a shape and dimensions corresponding to the target shape of the plate-shaped workpiece is formed on the outer periphery of the grinding wheel. The outer periphery of the plate-shaped workpiece is then ground by inserting the outer periphery of the plate-shaped workpiece into the groove and grinding the groove using the inner periphery of the groove. Repeated chamfering operations can cause the inner periphery of the groove to wear or break, changing the shape and dimensions and reducing the processing accuracy.

[0003] When chamfering is performed over a long period of time, the grinding wheel needs to be replaced or reshaped. Therefore, the grinding wheel is processed using a truing wheel (truer), i.e., truing is performed. The truing wheel is produced by abutting the master wheel, which has a formed groove corresponding to the target shape of the plate-shaped workpiece, on the inner peripheral surface of the groove and grinding it. The grinding wheel used for actual chamfering of the workpiece is then abutted against the outer peripheral surface of the truing wheel, forming a formed groove similar to that of the master wheel and forming the desired shape and dimensions. The truing wheel is made of a material (e.g., a GC wheel) harder than the grinding wheel used for chamfering (e.g., a resin-bonded wheel), and the master wheel is made of a material (e.g., a metal-bonded wheel) harder than the truing wheel.

[0004] In order to easily true the groove shape of a chamfering grindstone used in a chamfering device for plate-like objects to a desired shape, it is known to transfer the groove shape of a master grindstone to the outer periphery of a truing grindstone, and then transfer the outer periphery shape of this truing grindstone to the chamfering grindstone, thereby forming grooves in the chamfering grindstone, as described, for example, in Patent Document 1.

[0005] In addition, in normal grinding, the chamfered portion is ground with the main surface of the wafer perpendicular to the rotation axis of the resin grinding wheel, but in this case, grinding marks in the circumferential direction tend to occur in the chamfered portion. Therefore, it is known to perform so-called helical grinding, in which the chamfered portion of the wafer is ground by tilting, for example, a resin bond grinding wheel relative to the wafer.

[0006] When performing helical grinding, if a truer with an edge formed to be symmetrical up and down is used to form or correct (truing) grooves on a resin grinding wheel, the inclination of the resin grinding wheel causes the truer to twist, resulting in the grooves in the resin grinding wheel being machined to have an asymmetrical shape up and down.For this reason, Patent Document 2 describes a method in which the upper or lower part of the planned groove position is machined with a truer whose thickness is smaller than the width of the groove in the grinding wheel used to grind the chamfered part of the wafer, and then the truer is lowered or raised in the thickness direction relative to the grinding wheel to perform the machining, thereby improving the truing transfer rate and processability, as well as improving the accuracy of the grooves formed by the truer.

[0007] Furthermore, in order to perform chamfering easily, efficiently and with high precision, to simplify the mechanism for supporting and driving the workpiece and grinding wheel, and to facilitate shaping of the grinding wheel, Patent Document 3 describes that the grinding wheel is moved relative to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped part of the grinding wheel at the contact point between the convex grinding part on the outer periphery of the grinding wheel and the workpiece. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-153085 [Patent Document 2] Japanese Patent Application Publication No. 2018-167331 [Patent Document 3] Patent Publication No. 2021-181151 Summary of the Invention [Problem to be solved by the invention]

[0009] In the above-mentioned prior art, the method described in Patent Document 1 involves cutting the truer directly into the groove of a master grinding wheel, which is a grinding wheel for forming the truer, and transferring the groove shape to the edge of the truer. Therefore, only one type of shape can be accommodated per groove of the master grinding wheel. Therefore, it is difficult to change the shape of the truer, and it is not possible to accommodate changes in the processing conditions of the chamfering device, such as the setting of the rotation axis of the grinding wheel.

[0010] The methods described in Patent Documents 2 and 3 make it possible to change the shape of the truer, but they are not sufficient for making fine corrections to approximate the desired processed shape or for further improving the accuracy of the truer edge shape.

[0011] The object of the present invention is to solve the problems of the prior art described above, to reduce the time and cost required to create truers, and to standardize quality, while improving the truing transfer rate, workability, and accuracy of the grooves formed in the truers, and in particular to further improve the accuracy of the edge shape of the truer, and to improve not only the dimensional accuracy of the groove shape of the outer peripheral precision grinding wheel to which the shape is transferred, but also the accuracy of the final chamfered shape by preventing the groove angle and end corners from being rounded. [Means for solving the problem]

[0012] In order to achieve the above object, the present invention is configured as follows.

[0013] [1] A truer forming method for truing, in which a groove in a grinding wheel that grinds a chamfered portion of a wafer is formed using a disk-shaped truer, comprising: a step A of adjusting the diameter and rough shape of the truer using a master grinding wheel that forms the truer; and a step B of shaping the edge of the truer into a target shape, wherein the steps A and B are performed using each of a plurality of master grooves of different shapes that the master grinding wheel has, or the steps A and B are performed using each of differently shaped portions of at least one master groove that the master grinding wheel has. [2] The truer forming method according to [1], wherein the steps A and B are performed using a first groove and a second groove, which are master grooves of different shapes that the master grindstone has. [3] A method for forming a truer according to [2], characterized in that after the truer is processed in the first groove, an edge processing process is performed using the tip of the second groove. [4] A truer forming method according to [2], characterized in that the tip of the second groove has a larger radius of the R-shaped portion than the tip of the first groove. [5] A method for forming a truer according to any one of [2] to [4], characterized in that when chamfering the truer in the master groove, the chamfering is performed in the direction in which the truer is pulled. [6] A method for forming a truer lure according to [3], characterized in that corner R processing, which reduces the travel distance of the truer lure and processes the shape, radius, and roundness of the corners, is performed using the tip of the second groove. [7] A true molding method according to [6], characterized in that the corner R processing of the lower surface (lower surface) is performed after the corner R processing of the upper surface (upper surface) is completed. [8] A truer forming method according to [7], characterized in that the parameters of the movement start point (entrance point, entry speed), processing speed, escape position, escape speed, rotation speed of the truer, processing start point, and processing end point are performed by taking two sets of values for the corner R processing (upper surface) and the corner R processing (lower surface). [9] A truss forming method according to [8], characterized in that the amplitude, the processing speed, the spark-out time, and the number of reciprocating motions are set independently for each processing as a traverse operation.

[10] The truer forming method described in [1], wherein the steps A and B are carried out using differently shaped portions of at least one master groove of the master grinding wheel, and the step B is carried out using the tip of the master groove.

[11] The truer molding method according to

[10] , wherein step A is carried out using the bottom of the master groove. [Effects of the Invention]

[0014] According to the present invention, the time and cost required to create truers can be reduced and quality can be standardized, and the truing transfer rate, processability, and accuracy of the grooves formed in the truers are improved. In particular, the accuracy of the edge shape of the truer is further improved, and not only is the dimensional accuracy of the groove shape of the outer peripheral precision grinding wheel, which is the object to which the shape is transferred, improved, but the accuracy of the final chamfered shape can also be improved by preventing the groove angle and end corners from being rounded. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a front view showing a main part of a chamfering device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a side view illustrating a truing process according to an embodiment. [Figure 3] 10 is a side view showing a state in which a wafer W is processed by a grinding wheel 55 having a concave groove in one embodiment. FIG. [Figure 4] 10A and 10B are side views showing a method for forming a truer 41 in one embodiment. [Figure 5] FIG. 10 is a side view showing high-precision machining of the second groove 62 in one embodiment. [Figure 6] 4 is a flowchart showing a procedure for forming a truer 41 according to an embodiment. [Figure 7] 7 is a flowchart showing the procedure of the edge processing process in FIG. 6 according to one embodiment. [Figure 8] 10 is an explanatory diagram showing a procedure for forming a truer 41 in one embodiment (second embodiment) of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] (First embodiment) An embodiment (first embodiment) of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a front view showing the main parts of a wafer chamfering apparatus according to one embodiment of the present invention. The wafer chamfering apparatus 10 is composed of a wafer feed unit 20, a grindstone rotation unit 50, a wafer supply / storage unit (not shown), a wafer cleaning / drying unit, a wafer transport means, and a controller for controlling the operation of each part of the wafer chamfering apparatus.

[0017] The wafer feed unit 20 has an X-axis base 21 placed on the main body base 11, two X-axis guide rails 22, four X-axis linear guides 23, and an X-table 24 that is moved in the X direction in the figure by an X-axis drive mechanism 25 consisting of a ball screw and a stepping motor.

[0018] The X table 24 incorporates a Y table 28 that is moved in the Y direction in the figure by a Y-axis drive mechanism consisting of two Y-axis guide rails 26, four Y-axis linear guides 27, a ball screw and a stepping motor (not shown).

[0019] The Y table 28 incorporates a Z table 31 that is guided by two Z-axis guide rails 29 and four Z-axis linear guides (not shown) and moved in the Z direction in the figure by a Z-axis drive mechanism 30 consisting of a ball screw and a stepping motor.

[0020] The Z table 31 incorporates a θ-axis motor 32 and a θ-spindle 33, and a wafer table 34 for suction-mounting a wafer W (a plate-shaped workpiece) is attached to the θ-spindle 33. The wafer table 34 rotates in the θ direction in the figure around the wafer table rotation axis CW.

[0021] The wafer W and the truer 41 are rotated in the θ direction in the drawing and moved in the X, Y, and Z directions by the wafer feed unit 20.

[0022] The grinding wheel rotation unit 50 has a peripheral grinding wheel spindle 51 to which a peripheral rough grinding wheel 52 is attached and which is rotated around its axis by a peripheral grinding wheel motor (not shown), a peripheral fine grinding spindle 54 attached to a turntable 53 located above, and a peripheral fine grinding motor 56.

[0023] A grinding wheel 55, which is a chamfering wheel used to finish grind the outer periphery of the wafer W, is attached to the outer periphery precision grinding spindle 54. The outer periphery precision grinding spindle 54 performs finish processing of the outer periphery chamfer of the wafer W with its rotation axis tilted at an angle of 3 to 15°, preferably 6 to 10°, relative to the rotation axis of the wafer W. This performs helical grinding, and although weak grinding marks are left in the diagonal direction on the chamfered portion of the wafer W, it has the effect of improving the surface roughness of the chamfered portion compared to normal grinding.

[0024] The wafer processing process is carried out in the following order: slicing → chamfering → lapping → etching → donor killer → fine chamfering, with various cleaning procedures used between processes to remove dirt. Materials such as silicon are hard and brittle, and if the edge of the wafer remains sharp during slicing, it can easily crack or chip during handling in subsequent processing steps such as transport and alignment, and the fragments can scratch or contaminate the wafer surface. To prevent this, in the chamfering process, the edge of the cut wafer is chamfered using a diamond-coated chamfering wheel.

[0025] The grinding wheel 55 is made of a metal powder such as Fe, Cr, Cu, or the like, mixed with diamond abrasive grains and molded. The material is preferably made of a phenolic resin, epoxy resin, polyimide resin, polystyrene resin, polyethylene resin, or the like, mixed with diamond abrasive grains or cubic boron nitride abrasive grains.

[0026] The grinding wheel 55 is a resin-bonded diamond abrasive wheel with a diameter of 50 mm and a grit size of #3000. The outer periphery precision grinding spindle 54 is a spindle driven by a built-in motor using an air bearing, and rotates at a rotational speed of 35,000 rpm.

[0027] 2 is a side view showing the truing process, in which a chamfering groove is formed in a grinding wheel 55 by a truing tool 41. The disk-shaped truing tool 41 is attached to the bottom of the wafer table 34 concentrically with the wafer table rotation axis, and is rotated by the wafer table 34. The outer periphery of the truing tool 41 is chamfered in advance using a master grinding tool (see FIG. 3). In other words, a chamfering groove is formed in the grinding wheel 55 using a truing tool 41 whose outer periphery has been transferred with the cross-sectional shape of a master groove (see FIG. 3).

[0028] The material of the truer 41 is preferably abrasive grains made of silicon carbide, for example, which are bound with phenolic resin, with fillers added as necessary, and molded into a disk-shaped truer 41. The truer 41 may also be a disk-shaped GC (Green silicon carbide) grinding wheel or WA (White fused alumina) grinding wheel having an outer diameter equal to or smaller than that of the wafer W to be processed and the same thickness, and the grain size of the grinding wheel is preferably about #320.

[0029] 3 shows a side view of a wafer W being processed with a grinding wheel 55 having a concave groove. When a convex grinding wheel, as described in Patent Document 3, is used to process the straight line portion, the processing is performed by point contact, which results in uneven wear of the grinding wheel, leaving streaks as the processing trace, resulting in poor surface roughness, and a long processing time. Furthermore, point contact processing using a convex grinding wheel results in a long processing time and a release of processing stress, making it difficult to form the target shape.

[0030] On the other hand, when the rough shape is formed using a concave groove (concave grinding wheel) as shown in Figure 3(a), the stresses on the upper and lower slopes are offset, reducing the escape of processing stress, and the shape is less likely to become irregular even when processing straight sections. Furthermore, when machining with a concave groove, the straight sections also undergo line contact, so machining time is short, no streaks are left, the surface roughness is improved, the machining load is reduced, and the life of the grinding wheel is dramatically improved.

[0031] FIG. 3(b) shows that the tip of the grinding wheel 55, indicated by arrow A (arrow A; shown as a straight line in the figure, but may also have a curve (surface)), which does not contribute to the processing of the diameter or rough shape, is used to process the desired finished shape. This allows for more accurate processing of the shape, radius, roundness, etc. of corners. In this case, pulling the wafer W as indicated by arrow B increases the contact area between the wafer W and the grinding wheel 55, thereby reducing the processing load and extending the grinding wheel's life. Furthermore, if the difference between the shape before processing and the target shape is large, the amount of grinding at the tip increases, resulting in greater wear on the grinding wheel 55. Therefore, it is preferable to previously approximate the groove shape of the grinding wheel 55 to the target shape.

[0032] 4(a) is a side view showing a method for forming the truer 41. The master grindstone 60 for forming the truer 41 has a plurality of grooves (first groove 61, second groove 62) as master grooves. The first groove 61 is for adjusting the diameter and rough shape of the truer 41 (adjusting the diameter and rough shape). The first groove 61 may be a forming groove, and the adjustment of the diameter and rough shape by the first groove 61 may be achieved by transferring the groove shape of the first groove 61 to the truer 41. On the other hand, the second groove 62 is used to adjust the edge of the truer 41 to a target shape (any desired cross-sectional shape). The second groove 62 has a rounded portion with a larger radius at its tip (opening). In other words, the first groove 61 and the second groove 62 have different shapes. By using the rounded portion of the second groove, a truer 41 with any cross-sectional shape can be obtained that cannot be obtained by simply transferring the groove shape.

[0033] 4(b) is an enlarged view of the second groove 62. The second groove 62 has a straight portion 81 that is approximately parallel to the thickness direction (Z direction) of the master grindstone 60, upper and lower inclined portions 82 that extend from the ends of the straight portion 81, and upper and lower rounded portions 83 that have curves that extend from the ends of the inclined portions 82 to the openings. Although the second groove 62 in FIG. 4(b) has a straight portion 81, an inclined portion 82, and an R-shaped portion 83, it is not limited to the above, and the second groove 62 may have any portion as long as it has a straight portion 81 and an R-shaped portion 83. In addition, in the drawing, the straight portion 81 and the inclined portion 82 are depicted as straight lines (in cross section), but are not limited to the above and may have curved lines (curved surfaces).

[0034] The master grindstone 60 is rotated at a rotational speed of, for example, 8000 rpm. In this state, the Z-table 31 is moved by the Z-axis drive mechanism 30, and the truer 41 is positioned at a height that matches the height of each groove of the master grindstone 60.

[0035] Next, the Y table 28 is moved toward the master grindstone 60. As the Y table 28 moves in the Y direction, the outer periphery of the truer 41 is cut into the master groove of the master grindstone 60, and the wafer table 34 is rotated slowly one revolution by the θ-axis motor 32. Then, the outer periphery of the truer 41 is chamfered, and the shape of the master groove is transferred to the outer periphery of the truer 41. Next, the truer 41 is moved in a direction away from the master grindstone 60, and the transfer of the cross-sectional shape of the master groove to the cross-sectional shape of the outer periphery of the truer 41 is completed.

[0036] The method of transferring the master groove to the truer 41, that is, the molding process of the truer 41, involves cutting the outer periphery of the truer 41 into the first groove 61 as shown by arrow D as described above, and processing the diameter and roughly adjusting the shape of the truer 41. Next, edge processing is performed using mainly the R-shaped portion 83 of the second groove 62 with high precision, including adjustment to an arbitrary cross-sectional shape.

[0037] Figure 5 is a side view showing high-precision processing using the second groove 62, Figure 6 is a flowchart showing the steps of the molding processing of the truer 41, and Figure 7 is a flowchart showing the detailed steps of the edge processing processing in Figure 6 (step 4 in Figure 6). The outline of the method for forming the truer 41 according to Figure 6 is as follows: (1) inputting various conditions (Step 1), (2) calculating the processing conditions (processing start point and processing end point) by the chamfering device based on the input various conditions, (3) forming the truer 41 mainly by diameter processing (Step 3), and (4) edge processing (Step 4).

[0038] (Steps 1 and 2) The various conditions to be input are parameters such as diameter, chamfering angle, tip shape (straight line length of end face m, face width n, size of corner R), movement start point (entry point, entry speed), chamfering processing speed, corner R processing speed, escape position, escape speed, rotation speed of truer 41, and rotation speed of master grinding wheel 60.

[0039] The chamfering method using this chamfering device includes not only transferring the shape of the master groove in step 3 described below, but also adjusting the master groove (second groove) to a desired shape using the R-shaped portion in step 4. Therefore, an example of the conditions to be input in this step may be data on an arbitrary and desired cross-sectional shape. The desired cross-sectional shape is preferably smaller than the cross-sectional shape after grinding by the first groove 61, which may be a formed groove, and can be any shape regardless of the groove shapes of the first groove 61 and the second groove 62. The machining conditions calculated by the chamfering device are mainly the machining start point and machining end point.

[0040] (Step 3: Process A) Step 3 is a process for adjusting the diameter and rough shape of the truer (Step A). This step is performed using the first groove 61. In this step, the master grinding wheel 60 is rotated at a rotational speed of, for example, 8000 rpm. Processing begins by positioning the truer 41 at a height that matches the master groove (first groove 61) of the master grinding wheel 60. The truer 41 is moved toward the master grinding wheel 60 as indicated by arrow D, and the outer periphery of the truer 41 is cut into the master groove (first groove 61) of the master grinding wheel 60, mainly chamfering the end face of the outer periphery of the truer 41. The diameter processing process has two processing conditions as parameters: corner R processing (upper surface) and corner R processing (lower surface). In one mode, corner R processing (upper surface) is performed first, followed by corner R processing (lower surface).

[0041] As mentioned above, in this method, the diameter and rough shape are adjusted using concave grooves, which makes it difficult for the master grinding wheel and truer to come into point contact, making it difficult for processing stress to escape, and as a result, grinding can be performed efficiently.

[0042] (Step 4: In detail, steps 401 to 407: Process B) Step 4 is a process of forming the edge of the truer into a target shape (Process B). The processing in this step is performed using a second groove 62 having a (cross-sectional) shape different from that of the first groove 61. "A second groove 62 having a shape different from that of the first groove 61" means, as one form, that the second groove 62 has an R-shaped portion at the tip (the portion close to the opening), and any other form may be used as long as it is different in shape from the portion used in Process A. Returning to the flow, specifically, after the diameter and rough shape are machined in the first groove 61, the truer 41 is moved to the movement starting point that coincides with the height of the second groove 62 shown in Figure 5(a) (step 401).

[0043] The chamfering device sets parameters for the machining conditions based on the previously input conditions (data such as the desired cross-sectional shape) (step 402). Next, the truer 41 moves to the approach point at a predetermined approach speed (step 403). The truer 41 starts rotating (step 404) and chamfers the portion indicated by the bold line in Figure 5(b) at a predetermined chamfering angle (step 405). At this time, since the second groove 62 is a concave groove, machining is performed by line contact, which shortens the machining time, leaves no streaks, improves surface roughness, and reduces the machining load. It is also desirable to perform the chamfering in the direction of pulling the truer 41, as indicated by arrow B in Figure 5(c), to reduce the machining load.

[0044] After the chamfering, the travel distance of the truer 41 (i.e., the processing feed amount) is reduced, and corner R processing is performed to process the finer details, specifically the shape, radius, roundness, etc. of the corners (step 406). Corner R processing (upper surface) is performed using the tip with the R-shaped portion indicated by arrow A, which does not contribute to the diameter processing of the second groove 62. The tip of the second groove 62 has a larger radius of the R-shaped portion than the tip of the first groove 61. Therefore, the shape, radius, roundness, etc. of the corners of the truer 41 are processed with higher precision, without leaving any streaks, and the surface roughness is improved.

[0045] After the corner R machining (upper surface) is completed, the corner R machining (lower surface) is performed, so in step 401 the machine moves to the corresponding movement start point, and steps 401 to 405 are similarly repeated. Also, parameters such as the movement start point (entrance point, entry speed), escape position, machining speed, escape speed, rotation speed of the tool 41, machining start point, machining end point, etc. are performed by taking two sets of values for corner R machining (upper surface) and corner R machining (lower surface).

[0046] For each process, it is preferable to set the amplitude, processing speed, spark-out time, and number of reciprocations as a traverse operation independently to improve the surface roughness. Spark-out refers to the process of continuing grinding without cutting at the end of the grinding process, and the processing proceeds in small increments.

[0047] Truing involves using a truer 41 to appropriately correct the grooves in the grinding wheel 55 when the specified outer peripheral surface width, outer peripheral angle, and outer peripheral shape are no longer met due to a decrease in grinding ability. Truing according to the present invention not only increases the number of wafers that can be processed per truing, but also extends the life of even resin grinding wheels, allowing more wafers to be processed with one resin grinding wheel. This also reduces the cost of semiconductor wafer manufacturing.

[0048] According to this embodiment, even when the grinding wheel 55 is changed to another shape, there is no need to use a different truer forming grinding wheel (groove). Therefore, this embodiment not only improves the accuracy of the grinding wheel 55, but also eliminates the need to replace the grinding wheel or to manufacture a new grinding wheel, which not only reduces the cost compared to manufacturing a new grinding wheel, but also shortens the time from ordering from the grinding wheel manufacturer to delivery of the grinding wheel.

[0049] (Second embodiment) Hereinafter, a second embodiment will be described in which the second groove 62 is used to process the diameter and rough shape, and to adjust to a desired shape (edge processing). Note that the wafer chamfering device used is the same as that in the first embodiment, and therefore a description thereof will be omitted. The following description will focus on the differences from the first embodiment.

[0050] FIG. 8 is an explanatory diagram showing the procedure of the molding process of the truer 41 in this embodiment, which is performed using the second groove 62. 8(a) shows the state before processing of the truer 41. In the following steps, first, the diameter and rough shape of this truer 41 are adjusted to have a cross-sectional shape 84.

[0051] It should be noted that the drawings are schematic, and the shapes are exaggerated in order to clearly illustrate the difference in shape between before and after processing of the truer 41. In addition, in FIG. 8, the object to be processed (object to be ground) is the truer 41, but this method is not limited to the truer 41 and can also be applied to grinding wafers and the like.

[0052] 8(b) shows how the truer 41 is cut into the rotating master grindstone 60 to adjust the diameter and rough shape of the truer 41 to a cross-sectional shape 84 (step A). At this time, the end of the truer 41 comes into contact with the straight portion 81 and the sloped portion 82, which are the bottom of the second groove 62 of the master grindstone, and is ground. In other words, in this embodiment, step A is performed using the straight portion 81 and the sloped portion 82, which are the bottom of the second groove. The straight portion 81 and the inclined portion 82 have the same function as a concave groove such as the first groove 61 already described, and can adjust the diameter and rough shape of the truer 41 mainly in a line contact state while preventing stress from escaping.

[0053] After the rough shape adjustment is completed and the cross-sectional shape of the truer 41 is in the state of 84, edge processing is then performed using the R-shaped portion 83 (step B). This step B is performed using a portion of the second groove 62 that is different in shape from the portion used in the processing of step A. Specifically, it is performed using the R-shaped portion 83 at the tip end (the tip end in the opening direction) of the second groove 62.

[0054] As already explained, the straight line portion 81 and the inclined surface portion 82 used in the process A function as a concave groove, and can more efficiently adjust the rough shape without releasing stress by making line contact with the truer 41. In other words, the groove shape can be easily transferred to the truer 41.

[0055] On the other hand, the R-shaped portion 83 used in process B has a different shape, that is, it is convex toward the inside of the groove, while the straight portion 81 and the sloped portion 82 are configured in a straight line. When the truer 41 is brought into contact with this, it can be machined into any shape depending on the position and the way of contact.

[0056] Returning to the explanation of the process, once the adjustment of the diameter and rough shape is completed, the truer 41 moves in the Z(-) direction while moving away from the straight portion 81 and the inclined portion 82 (to change the position of use) so as to follow the R-shaped portion 83 in the Z(-) direction of the second groove 62. The arrow in Figure 8(b) indicates the movement direction of the truer 41.

[0057] The edge of the truer 41 is processed while moving along the R-shaped portion 83. Figures 8(c) and 8(d) show the state of edge processing by the R-shaped portion 83. In this process, the edge shape and the like are adjusted while moving the truer 41 (reciprocating as necessary) along the R-shaped portion 83 based on the data of the desired cross-sectional shape received in step 1 of Figure 6 already described. Typically, when adjusting the diameter and rough shape (step A), it is preferable that the R-shaped portion 83 is not in contact with the truer 41. Because the R-shaped portion 83 has a curved shape, its cross-sectional shape can be easily adjusted as desired by changing the way the truer 41 is applied, i.e., by changing the way the truer 41 is moved in the Y- and Z-axis directions (step B).

[0058] Next, in the same manner, as shown in Figures 8(e) and 8(f), the shape of the (mainly) upper end side of the truer 41 is adjusted by moving the truer 41 along the R-shaped portion 83 on the upper (Z(+)) side of the second groove 62. In this embodiment, the lower side of the truer 41 is processed first, but as already explained, the upper side of the truer 41 may be processed first.

[0059] 8(g) shows the truer 41 after edge processing is completed. The cross-sectional shape 85 of the truer 41 after adjustment in this manner may be different from the shape 84 after the diameter and rough shape have been adjusted by the straight portion 81 and the sloped portion 82. In other words, according to this method, the diameter and rough shape can be adjusted using the second groove 62, and further, any cross-sectional shape can be obtained.

[0060] Conventionally, in forming truers using a master grindstone, the shape of each master groove corresponds to the cross-sectional shape of each truer in order to transfer the shape of the master groove to the truer. Therefore, when adjusting multiple truers to have different cross-sectional shapes, methods have been adopted in which multiple master grindstones are prepared and exchanged to transfer the shapes, or a master grindstone having multiple master grooves is used to transfer the shapes of different master grooves to each.

[0061] However, according to the present method, the cross-sectional shape of the truer can be adjusted arbitrarily using a master groove having an R-shaped portion at the opening, without using a master grindstone or a plurality of master grooves. [Explanation of symbols]

[0062] 10...Wafer chamfering device 11...Main body base 20...Wafer feeding unit 21...X-axis base 22...X-axis guide rail 23...X-axis linear guide 24...X table 25...X-axis drive mechanism 26...Y-axis guide rail 27...Y-axis linear guide 28...Y table 29...Z-axis guide rail 30...Z-axis drive mechanism 31...Z table 32...θ-axis motor 33...θ spindle 34...Wafer table 41...True lure 50...Grinding stone rotation unit 51...Periphery grinding wheel spindle 52...Periphery rough grinding wheel 53...Turntable 54...Periphery precision grinding spindle 55...Grinding wheel 56...Periphery precision motor 60...Master grindstone 61…1st groove 62…Second groove 81...Straight section 82...Sloped section 83...R-shaped part 84…Cross-sectional shape 85…Cross-sectional shape CW: Wafer table rotation axis GC…disk shape W...wafer n…Surface width

Claims

1. A method for forming a truer groove of a grinding wheel for chamfering a wafer by transferring the shape of the truer groove to the wafer, comprising: The method includes molding the disk-shaped truer by bringing it into contact with a master groove of a rotating master grindstone, The method for molding a truer, wherein the master groove has an R-shaped portion that is convex toward the inside of the master groove.

2. 2. The method for forming a truer according to claim 1, wherein in forming the truer, the shape of the edge of the truer is adjusted by moving the truer along the R-shaped portion while keeping the edge in contact with the R-shaped portion.

3. 3. The method for molding a truer lure according to claim 2, wherein the master groove has, in a cross-sectional view, a linear bottom portion, linear inclined portions extending radially from both ends of the bottom portion, and the R-shaped portions continuing to each of the inclined portions.

4. 4. The method for forming a truer according to claim 3, wherein in forming the truer, the diameter and / or the rough shape of the truer is adjusted by bringing the truer into contact with the bottom and the inclined surface.

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