Wafer chamfering device

Abstract

A wafer chamfering device, which trues (S4) an abrasive grinding wheel 16 by a truer 10 and grinds an edge portion of the outer circumference of a wafer W by using the abrasive grinding wheel 16 that has been trued (S4), comprises: a truer-creation grinding wheel 15 that creates an edge shape of the truer 10 in accordance with a truer machining program 50; a control unit 30 that controls the truer-creation grinding wheel 15 and a machining condition for the truer 10 and the abrasive grinding wheel 16; and a truer-creation grinding wheel evaluation unit 39 that evaluates the truer-creation grinding wheel 15 according to the result of measuring the edge shape of the truer 10. The chamfering device creates and updates the truer machining program 50 on the basis of the evaluation, and improves the delivery quality of the wafer pertaining to acceptable accuracy, variations, and the like, and extends and maximizes the service life of the truer-creation grinding wheel.

Description

Wafer chamfering equipment

[0001] The present invention relates to a wafer chamfering device that uses a truer to transfer (truing) a peripheral precision grinding wheel (grinding wheel) having a groove shape used in a chamfering device for the end face of a semiconductor wafer, and then uses the transferred peripheral precision grinding wheel to grind the peripheral edge portion of a wafer (semiconductor material substrate).

[0002] In recent years, there has been an increasing demand for higher precision and quality improvements in grinding wheels with groove shapes used in wafer chamfering, with the aim of achieving high-mix, low-volume production, improving wafer quality, and increasing yield.

[0003] In addition, semiconductors using materials that have a large band gap (UWBG) and strong bonds between the atoms that make up the crystal, such as SiC (silicon carbide), which is a compound of carbon (C) and silicon (Si), and materials that are not easily broken, such as GaN (gallium nitride), gallium oxide, AlGaN, and diamond, are expected to be smaller than silicon semiconductors, have lower power consumption, are highly efficient, and are semiconductor materials with excellent radiation resistance, and are being put into practical use. However, UWBG materials such as 4H-SiC are difficult to process, so there is a strong demand for higher precision and quality improvements in the groove shape of grinding wheels.

[0004] Chamfering in the manufacturing process of semiconductor wafers requires truing the grinding wheel with a truer and measuring the edge shape of the wafer after grinding, and this process must be repeated until the wafer achieves the desired shape.

[0005] Furthermore, in the finishing process of the outer peripheral chamfer of semiconductor wafers, it is known to perform so-called helical grinding, in which the grinding wheel is tilted relative to the wafer to grind the chamfer, in order to prevent the generation of grinding marks in the circumferential direction.However, helical grinding requires delicate adjustments for the formation of the shape by truing the grinding wheel, which is time-consuming and requires a skilled, dedicated person.

[0006] Patent Document 1 describes that in truing for helical grinding, in which grooves are formed using a truer, the upper or lower part of the groove formed in the grinding wheel is processed with a truer in order to improve the transfer rate and processability as well as the groove accuracy of the wafer grinding wheel formed by the truer.

[0007] Furthermore, Patent Document 2 describes forming the edge of the truer into a groove shape that is asymmetrical in the vertical direction, and forming the groove shape by grinding with the truer and a wafer grinding wheel tilted relative to each other.

[0008] JP 2018-167331 A JP 2007-165712 A

[0009] In the above-mentioned prior art, the one described in Patent Document 1 requires adjustments by a skilled, dedicated person to move the truer when truing the grinding wheel used for chamfering.

[0010] Furthermore, the method described in Patent Document 2 has a poor transfer rate due to the load on the truer in the vertical direction and deformation of the truer in the rotational direction, which affects the accuracy of the grooves formed and the truing time, resulting in a significant decrease in truing efficiency and is insufficient for improving the accuracy of the overall shape of a grinding wheel having a groove shape.

[0011] Furthermore, the above-mentioned conventional technology requires a truer-prepared grinding wheel that creates the edge of the truer using a truer processing program. However, if the truer-prepared grinding wheel continues to process a specific part of the grinding wheel groove using the same truer processing program, the grinding wheel groove will become deformed due to wear and will no longer be able to withstand the design value, which means that the grinding wheel will reach the end of its life sooner.

[0012] The object of the present invention is to solve the problems of the prior art described above, and to provide a wafer chamfering device which can improve the precision and quality of the shape of the groove-shaped grinding wheel used in the wafer chamfering device by improving the precision of truing, and ultimately improve the shipping quality of the wafer, such as the allowable precision and variation, even for difficult-to-process materials, and can extend and maximize the life of the grinding wheel made by the truing device.

[0013] In order to achieve the above-mentioned object, the present invention provides a wafer chamfering device that uses a truer to true a grinding wheel and grinds the outer peripheral edge of a wafer using the trued grinding wheel, the device comprising: a truer-making grinding wheel that creates the edge shape of the truer in accordance with a truer processing program; a control unit that controls the truer-making grinding wheel and the processing conditions for the truer and the grinding wheel; and a truer-making grinding wheel evaluation unit that measures the edge shape of the truer and evaluates the truer-making grinding wheel, and creates and updates the truer processing program based on the evaluation.

[0014] Furthermore, in the above-mentioned wafer chamfering device, it is preferable to include a shape measuring unit that measures the cross-sectional shape of the wafer, a processing condition database in which the shape of the wafer processed by the grinding wheel is measured by the shape measuring unit, compared with a target shape, and stored in association with processing conditions, and a learning model constructed from the processing condition database, and the Truer-prepared grinding wheel evaluation unit evaluates the Truer-prepared grinding wheel based on the learning model.

[0015] Furthermore, in the above-described wafer chamfering device, it is preferable that the truer manufacturing grindstone evaluation unit updates the truer processing program when it evaluates that the truer manufacturing grindstone is deformed due to wear.

[0016] Furthermore, in the above-mentioned wafer chamfering device, it is preferable that the truer processing program is created by combining both down-cutting and up-cutting tool paths for the truer manufacturing grindstone.

[0017] Furthermore, in the above-mentioned wafer chamfering device, the edge shape of the truer is formed by moving the work fixing part of the truer in the X-axis, Y-axis, and Z-axis directions and rotating the work fixing part along the rotation axis (θ ｗ ), and rotation about the pitch axis to perform grinding.

[0018] Furthermore, in the above-described wafer chamfering device, it is preferable that the truer processing program is updated by changing the processing procedure of the truer.

[0019] Furthermore, in the above-described wafer chamfering device, it is preferable that the Truer manufactured grindstone evaluation unit monitors the processing load, predicts and identifies unevenly worn portions of the Truer manufactured grindstone, and reflects the results in the Truer processing program.

[0020] Furthermore, in the above-mentioned wafer chamfering device, it is preferable that a motion program for uniformizing the processing use portion of the truer manufacturing grindstone is incorporated into the truer processing program.

[0021] According to the present invention, a truer processing program is created and updated to evaluate the truer manufacturing grinding wheel from the results of measuring the truer edge shape and to create the truer edge shape, thereby making it possible to obtain a wafer chamfering device that extends the life of the truer manufacturing grinding wheel and improves the precision and quality of the grinding wheel shape.

[0022] 1. Control flow chart of a wafer chamfering device according to one embodiment of the present invention. 2. Block diagram showing the overall system configuration of a chamfering device according to one embodiment. 3. Explanatory diagram showing the processing procedure for grinding the chamfered portion of a wafer edge. 4. Cross-sectional view of a truer and a grindstone for making the truer. 5. Side view showing the configuration of a machine axis in making the edge shape of a truer. 6. Explanatory diagram showing the making of the edge shape of a truer (Example 1 of making upper side surface width and lower side surface width). 7. Explanatory diagram showing the making of the edge shape of a truer (Example 2 of making upper side surface width and lower side surface width). 8. Explanatory diagram showing the making of the edge shape of a truer (Example 1 of making flat surface width). 1. Explanatory diagram showing shape creation (Example 2 of creation of flat width) Explanatory diagram showing edge shape creation of truer (Example 1 of creation of upper tip radius R1 and lower tip radius R2) Explanatory diagram showing edge shape creation of truer (Example 2 of creation of upper tip radius R1 and lower tip radius R2) Side cross-sectional view showing the processing state in edge shape creation of truer Explanatory diagram (Example 1) showing the processing procedure of truer 10 by truer processing program 50 Explanatory diagram (Example 2) showing the processing procedure of truer 10 by truer processing program 50 Explanatory diagram showing the state of grinding using the tip surface of the convex part of truer manufacturing grinding wheel 15

[0023] FIG. 1 is a control flowchart of a chamfering device for a wafer W according to one embodiment of the present invention, FIG. 2 is a block diagram showing the overall system configuration of the chamfering device according to one embodiment, and FIG. 3 is an explanatory diagram showing the processing procedure for grinding the chamfered portion of the wafer edge face.

[0024] 3, the chamfering is performed by grinding the edge shape of the truer 10 with a truer-making grindstone 15. The groove shape of the grinding wheel 16 is transferred (trued) by the truer 10, and then the outer peripheral shape of the wafer W is ground with the grinding wheel 16.

[0025] 3, the grinding wheel 16 is attached to a grinding wheel spindle 17 via a quill 18 and rotates. Because this is helical grinding, the truer 10 is ground with an upper surface angle θ1 and a lower surface angle θ2 on the end face, and the wafer W is ground with an upper surface angle θ1' and a lower surface angle θ2'.

[0026] Factors related to the machining accuracy during truing include bending, twisting, and vibration of the grinding wheel 16, the surface shape of the truer 10, the state of the abrasive grains, the force applied during shape transfer, deformation of the truer 10, processing heat and thermal expansion coefficient, and alignment of the truer 10 and grinding wheel 16. To improve machining accuracy, it is necessary to build a machining condition database 37 that analyzes the effect of deformation due to force, heat, etc. on machining accuracy, identify factors that have a strong influence on performance, and build a learning model 38 using machine learning for automation.

[0027] In particular, it is important to sense the positions of the truer 10 and the grinding wheel 16 in the grinding environment and align them based on measurements. Although not shown, truing requires the amount of cut into the grinding wheel 16 as a condition, so the wheel groove diameter D of the grinding wheel 16 is calculated sequentially.

[0028] Taking into consideration factors related to processing accuracy, the truer 10 is required to have an upper surface angle θ1 of the truer 10 < an upper surface angle θ1' of the wafer W, and a lower surface angle θ2 of the truer 10 < a lower surface angle θ2' of the wafer W. The allowable shape accuracy of the truer 10 is determined by the allowable shape accuracy (shipping quality) of the wafer W.

[0029] The edge shape of the truer 10 is created into a desired arbitrary shape by moving and grinding the edge portion of the truer 10 relative to the truer manufacturing grinding wheel 15 (using a machine axis attached to a table that fixes the workpiece). The environment in which the truer manufacturing grinding wheel 15 is installed is an environment where coolant, fallen abrasive grains, swarf, etc. are present, making it difficult to directly measure the shape of the grinding wheel grooves of the truer manufacturing grinding wheel 15. It is preferable to determine that the truer manufacturing grinding wheel 15 has reached the end of its life when it deviates from the allowable shape accuracy of the wafer W or the allowable shape accuracy of the truer 10.

[0030] The chamfering device according to one embodiment determines the change in shape of the grinding grooves of the truer-manufacturing grinding wheel 15 from the edge shape of the truer 10 that serves as the workpiece. The truer-manufacturing grinding wheel evaluation unit 39 evaluates the change in shape and surface roughness of the truer-manufacturing grinding wheel 15 due to wear, predicts (simulates) the life of the grinding grooves, and creates and updates the truer processing program 50 so as to maximize the life of the truer-manufacturing grinding wheel 15.

[0031] In other words, the chamfering device according to one embodiment evaluates and predicts deformation of the truer manufacturing grinding wheel 15 due to wear, etc., by using shape evaluation, etc., in which the edge shape of the truer 10 manufactured by the truer manufacturing grinding wheel 15 and the edge shape of the wafer W processed by the grinding wheel 16 transferred using the truer 10 are compared with the target shape.

[0032] Then, a truer processing program 50 is created to improve the life of the truer manufacturing grindstone 15 (step S1 in FIG. 1). The truer processing program 50 is created by constructing a learning model 38 by machine learning that defines the relationship between the edge shape of the truer 10, the grinding wheel 16, the edge shape of the wafer W, the life of the truer manufacturing grindstone 15, and the truer processing program 50.

[0033] Updating and creating the truer processing program 50 so as to maximize the life of the truer-prepared grinding wheel 15 reduces the frequency of replacement of the truer-prepared grinding wheel 15, and prevents the production line (operation) from being affected by the man-hours required for replacement and adjustment. This is particularly effective when the truer-prepared grinding wheel 15 is installed next to a grinding wheel for rough grinding of the outer periphery, where the number of grooves on the truer-prepared grinding wheel 15 is limited due to space constraints.

[0034] However, depending on the operating conditions, it may be preferable to operate the truer 10 without measuring the edge shape. In this case, evaluation of the change in the shape of the grinding wheel groove of the truer-made grinding wheel 15 and prediction of the lifespan may be performed by finding a correlation when creating the processing condition database 37 or as a result of learning.

[0035] 2, the control unit 30 controls, as processing conditions, the cutting depth, rotation speed, position, movement amount, processing load, etc. of the truer making grindstone 15, the truer 10, and the grinding stone 16. The shape measurement unit 35 is composed of a laser displacement meter, etc., and measures the two-dimensional cross-sectional shape and surface roughness, etc. of the truer 10, grinding stone 16, and wafer W, which are the workpieces (objects to be processed) of the chamfering device.

[0036] A grinding wheel 16 serving as a tool is attached to the grinding wheel spindle 17. Similarly, the truer-fabricated grinding wheel 15 may also be attached to the grinding wheel spindle 17. The truer-fabricated grinding wheel 15 may also be attached to another spindle. For example, as will be described later, it may be attached to another moving table 25-2. In this case, the truer-fabricated grinding wheel 15 may be provided together with other grinding wheels (for example, a rough grinding wheel, etc.) (on the same rotation axis). The wafer W and truer 10 serving as the workpiece are placed on the workpiece moving table 25 and fixed to a workpiece fixing unit 24 consisting of a vacuum chuck table, and are movable in the X-axis, Y-axis, and Z-axis directions and rotate around a rotation axis (θ ｗ ), and is capable of rotation about the pitch axis.

[0037] In addition, the system configuration preferably includes a displacement evaluation unit (not shown) that evaluates the deformation (displacement) of the truer 10 and grinding wheel 16 during machining. The displacement evaluation unit measures the deformation (displacement from no load) of the truer 10 and grinding wheel 16 during machining based on the modeled displacement conditions of the truer 10 and grinding wheel 16, and measures the vibration of the truer 10 and grinding wheel 16 during machining, and provides a rating (quantification based on standards).

[0038] The processing condition database 37 stores the results of monitoring the processing conditions of the truer 10 and the grinding wheel 16, such as the depth of cut, rotational speed, position, amount of movement, processing load, displacement, vibration, processing heat, etc., in association with the measurement results of the shape measuring unit 35 after truing.

[0039] The stored results are constructed as a learning model 38. The learning model 38 is obtained as a machining learning model 38-1, as shown in Fig. 1, and an analysis-based machining model 38-2 that reflects the shapes of the truer 10 and grinding wheel 16 measured before machining and the displacement conditions of the modeled truer 10 and grinding wheel 16.

[0040] In the control flowchart of Figure 1, the chamfering device optimizes the shape of the truer 10 so that the wafer W has the allowable shape accuracy of the target shape. The shape of the truer 10 is determined by taking into account the axial displacement conditions of the truer 10 that have been determined in advance, and a truer processing program 50 is created and updated with the upper surface angle θ1, lower surface angle θ2, chamfering angles, etc. of the end faces shown in Figure 3 (Step S1).

[0041] The truer processing program 50 reflects the cross-sectional shapes of the edge portions of the truer 10 and grinding wheel 16 measured by the shape measurement unit 35 (see Figure 2) before processing, the processing condition database 37, the processing learning model 38-1, the analysis-based processing model 38-2, and the evaluation results of the truer manufacturing grinding wheel evaluation unit 39.

[0042] The edge shape of the truer 10 is produced by grinding with the truer production grindstone 15 in accordance with the truer processing program 50. (Step S2) The shape measuring unit 35 measures the edge shape of the produced truer 10. (Step S3)

[0043] The groove shape of the grinding wheel 16 is transferred (trued) by the manufactured truer 10. (Step S4) If a displacement evaluation unit (not shown) is provided, the vibrations of the truer 10 and grinding wheel 16 during truing are monitored, and if a heat flow measurement unit or the like is provided, the temperature is also monitored.

[0044] The wafer W is ground by the grinding wheel 16 to which the shape has been transferred (step S5), and the shape measuring unit 35 determines whether the wafer W is acceptable or not with respect to a target shape, which is a design value (step S6).

[0045] If the wafer W ground by the grinding wheel 16 is not within the range of the allowable shape accuracy of the edge, the process returns to step S1. The processing conditions and the cross-sectional shape after processing are associated with each other and stored in a database as a processing condition database 37, and are reflected in the processing learning model 38, which is a processing learning model 38-1 and an analysis-based processing model 38-2 (step S7).

[0046] The processing condition database 37 stores the results of monitoring the processing conditions during truing (step S4) and during outer periphery grinding of the wafer W (step S5) in association with the truer processing program 50, the edge shape of the truer 10, the workpiece processing operating conditions, and the target workpiece shape. The processing learning model 38-1 is constructed from the processing condition database 37 stored in a database.

[0047] The Truer-manufactured grinding wheel evaluation unit 39 is constructed from a machining learning model 38-1, an analysis-based machining model 38-2, etc., which serve as the learning model 38, and evaluates the Truer-manufactured grinding wheel 15 based on the learning model 38. The Truer-manufactured grinding wheel evaluation unit 39 creates and updates the Truer-manufactured grinding wheel 15 based on an evaluation of a change in shape of the Truer-manufactured grinding wheel 15. For example, if the Truer-manufactured grinding wheel evaluation unit 39 evaluates that the Truer-manufactured grinding wheel 15 has been deformed due to wear or the like, it updates the Truer-manufactured grinding wheel 50.

[0048] The machining learning model 38-1 is a machine learning model that outputs the results of evaluation and judgment by a computer for the data that is the results accumulated in the machining condition database 37. The truer machining program 50 inputs a query to the machining learning model 38-1 as necessary to obtain the results of evaluation and judgment. In one embodiment, the learning model 38 is used to perform truing (step S2) and outer periphery grinding of the wafer W (step S5), thereby improving the accuracy and quality of the groove shape and suppressing shape variation.

[0049] 1 and 3 have been described as the transfer of the shape of the truer 10, but in order to achieve even higher precision, the upper or lower part of the groove to be formed in the grinding wheel 16 may be machined with the truer 10, and then the truer 10 may be ground one side at a time by lowering or raising it in the thickness direction relative to the grinding wheel 16.

[0050] The methods for evaluating the truer-prepared grinding wheel 15 by the truer-prepared grinding wheel evaluation unit 39 are: (1) a first method (without measuring the edge shape of the truer 10) in which judgment is made from the measurement results of the shape of the wafer W after grinding (step S6 in FIG. 1); and (2) a second method (without measuring the edge shape of the truer 10) in which judgment is made from the measurement results of the edge shape of the prepared truer (step S3 in FIG. 1). Either (1) or (2) or a combination of the first and second methods is implemented.

[0051] FIG. 4 shows a cross-sectional view of the truer 10 and the truer-making grindstone 15. The detailed shape of the truer 10 is the thickness t, the upper side width X1, the lower side width X2, the truer plane width X3, the upper tip radius R1, and the lower tip radius R2, and it is machined to have these dimensions. In the description of the present invention, the upper side width X1, the lower side width X2, the truer plane width X3, the upper tip radius R1, and the lower tip radius R2 may be used to refer to the surface of the truer 10 indicated by the dimension X1 in FIG. 4. The same applies to the lower side width X2, the truer plane width X3, the upper tip radius R1, the lower tip radius R2, and others. The truer 10 is pressed against the truer-making grindstone 15 as indicated by the arrows and ground.

[0052] The truer manufacturing grinding wheel 15 mainly has the upper side width X1 of the truer 10 corresponding to the upper inclined surface CX1 of the truer manufacturing grinding wheel 15, the lower side width X2 corresponding to the lower inclined surface CX2, the truer plane width X3 corresponding to the plane CX3, the upper tip radius R1 corresponding to the upper circular arc CR1, and the lower tip radius R2 corresponding to the lower circular arc CR2.

[0053] 5 is a side view showing the configuration of the machine axes in the edge shape creation (step S2 in FIG. 1) of the truer 10. The truer 10, which is the workpiece, is fixed to a workpiece fixing part 24, which is movable in the X-axis, Y-axis, and Z-axis directions and rotates around a rotation axis (θ ｗ ), and is installed on the workpiece moving stage 25-1 which can rotate around the pitch axis. However, the pitch axis is parallel to the Y axis, and the workpiece fixing part (workpiece) and the rotation axis θw rotate around the pitch axis, but at that time, the movement directions of the X axis and Z axis do not change. The truer making grindstone 15 is ｔ) axis as the rotation axis. The truer 10 side may have a four-axis configuration in which the pitch axis is omitted. Here, the up-down arrow K shown in FIG. 5 indicates that the tip of the truer 10 rotates up and down as indicated by the arrow as the truer 10 rotates around the pitch axis. The tip of the truer 10 on the side of the truer making grindstone 15 is indicated by an arrow as the truer tip.

[0054] 6 to 11 are explanatory diagrams showing the edge shape production of the truer 10. The grindstones used to grind the truer 10 shown here are the truer production grindstone 15 shown in FIG. 5 and its variation, the second truer production grindstone 19. In other words, it is shown that the truer 10 can be ground not only using the truer production grindstone 15 but also using the second truer production grindstone 19, which has a different shape. FIG. 6 shows Example 1 of production of the upper side width X1 and the lower side width X2 of the truer 10, FIG. 7 shows Example 2 of production of the upper side width X1 and the lower side width X2 of the truer 10, FIG. 8 shows Example 1 of production of the truer flat width X3, FIG. 9 shows Example 2 of production of the truer flat width X3, FIG. 10 shows Example 1 of production of the upper tip radius R1 and the lower tip radius R2, and FIG. 11 shows Example 2 of production of the upper tip radius R1 and the lower tip radius R2.

[0055] 6 shows a case where the truer 10 is not rotated around the pitch axis (see FIG. 5) of the truer 10, and shows that the upper side surface width X1 of the truer 10 is ground by the upper inclined surface CX1 of the truer making grindstone 15. At this time, the truer 10 is rotated by θ ｗ The Truer grinding wheel 15 rotates around the center of rotation, ｔ 6. Grinding is performed by rotating the truer 10 and truer-making grindstone 15 around the center of rotation, while the contact surfaces between them move relatively in the direction of the arrows in Figure 6. A similar method is also used when grinding the lower side width X2 with the lower slope CX2. The main grinding condition parameters are the cutting depth, rotation speed, rotation direction, spark-out time (when no cutting is performed at the end of the grinding process and only feed is applied or a small cutting is used to escape), and the movement speeds in X, Y, and Z.

[0056] 7 shows the grinding process when the truer 10 is rotated slightly around the pitch axis. As shown in this figure, by rotating the truer 10 slightly around the pitch axis, the upper side width X1 of the truer 10 can be processed not only on the upper inclined surface CX1 of the truer manufacturing grindstone 15, but also on any flat surface of the truer manufacturing grindstone 15.

[0057] Figure 8 shows grinding using a second truer making grinding stone 19, which is a grinding stone having a circular portion, by relatively moving the second truer making grinding stone 19 or the truer 10 so that the truer plane width X3 of the truer 10 moves in the direction of the arrow. In the case of a second truer making grinding stone 19 having a circular portion, the second truer making grinding stone 19 and the truer 10 can be relatively moved in the tangential direction at the contact point between the circular portion and the truer 10 to grind a flat portion of the truer plane width X3. Figure 9 shows that the same processing as in Figure 8 can also be performed on any flat portion of the truer making grinding stone 15. Also, Figure 9, like Figure 8, shows grinding by relatively moving the truer making grinding stone 15 and the truer 10 so that the truer plane width X3 of the truer 10 moves in the direction of the arrow.

[0058] FIG. 10 is a diagram showing the grinding of the upper tip radius R1 portion of the truer 10 using a second truer manufacturing grindstone 19 having a circular portion. As shown in FIG. 10, by slightly rotating the truer 10 about the pitch axis, the upper tip radius R1 portion of the truer 10 moves in the direction indicated by the arrow in the figure and is ground by the cylindrical portion of the second truer manufacturing grindstone 19. Note that a similar method is also used when grinding the lower tip radius R2 portion. FIG. 11 also shows that the same processing as in FIG. 10 can be performed. FIG. 11 shows that the grinding of the upper tip radius R1 portion of the truer 10 is performed by slightly rotating the truer 10 about the pitch axis in the direction indicated by the arrow, as in FIG. 10.

[0059] 12 is a side cross-sectional view showing a machining state in the creation of the edge shape of the truer 10. The creation of the edge shape of the truer 10 is performed in accordance with the truer machining program 50. The edge shape of the truer 10 is created by moving the truer 10 in the X-axis, Y-axis, and Z-axis directions of the workpiece fixing part 24, which serve as the machine axes, and rotating the truer 10 in the direction of the rotation axis (θ ｗ ), and grinding is performed by rotating the workpiece around the pitch axis.

[0060] For example, the truer machining program 50 may use the rotation axis (θ ｗ ) and the rotation axis (θ ｔ ) and the X and Z axes are rotated (down cut, up cut) while moving the X and Z axes by a predetermined amount at a predetermined position on the Y axis to create the shape of the truer 10. The main grinding condition parameters are the depth of cut, rotation speed, rotation direction (down / up), spark-out time, movement speeds of the X, Y, and Z axes, and rotation speed of the pitch axis.

[0061] The down cut is performed in the rotation direction D of the truer 10. ０ and the rotation direction D of the Truer manufactured grinding wheel 15 １ The grinding is performed by providing a speed difference at the contact portion (grinding portion) between the truer 10 and the truer manufacturing grindstone 15 while keeping the rotation direction D of the truer 10 the same. ０ The rotation direction D of the Truer manufactured grinding wheel 15 １ The truer machining program 50 creates a tool path TP of the truer manufacturing grinding wheel 15, which is the path along which the truer manufacturing grinding wheel 15 moves on the surface of the truer 10, by combining both down cutting and up cutting.

[0062] The tool path TP is optimized not only to shorten the movement time of the Truer-manufactured grinding wheel 15 but also to maximize the life of the grinding grooves of the Truer-manufactured grinding wheel 15 based on the evaluation by the Truer-manufactured grinding wheel evaluation unit 39. For example, the Truer-manufactured grinding wheel evaluation unit 39 monitors the machining load to predict and identify unevenly worn areas of the Truer-manufactured grinding wheel 15, and reflects the results in the Truer machining program 50 to maintain the design shape of the Truer-manufactured grinding wheel 15. In other words, a motion program that uniformly distributes the parts of the Truer-manufactured grinding wheel 15 used for machining is incorporated into the Truer machining program 50.

[0063] 13 and 14 are explanatory diagrams showing the machining procedure of the truer 10 according to the truer machining program 50. As explained in Fig. 6 to Fig. 11, the machining procedure of the truer 10 does not always have to be the same procedure, and can be changed as shown in Example 1 of Fig. 13 and Example 2 of Fig. 14. The machining procedure is changed based on the evaluation of the truer-made grindstone evaluation unit 39, and the portions of the truer-made grindstone 15 used for machining can be made uniform without being unevenly distributed.

[0064] 13, Example 1 will be described. The truer 10 is ground by feeding the truer plane width X3 (see FIG. 4) of the truer 10 as shown by the arrow with the plane CX3 (see FIG. 4) of the truer making grindstone 15. ｔ (Step 1) The upper tip radius R1 of the truer 10 (see FIG. 4) is prepared. (Step 2) The upper side width X1 of the truer 10 (see FIG. 4) is prepared. (Step 3) The shapes of the upper side width X1 and the upper tip radius R1 are adjusted and corrected. (Step 4) The diameter D of the truer 10 is adjusted and corrected. ｔ (Step 5) The lower tip radius R2 of the truer 10 (see FIG. 4) is created. (Step 6) The lower side width X2 of the truer 10 (see FIG. 4) is created. (Step 7) The shapes of the lower side width X2 and the lower tip radius R2 are adjusted and corrected. (Step 8) Steps 1 to 8 are repeated several times to create and finish the edge shape of the truer 10.

[0065] Example 2 of FIG. 14 will be explained. The upper tip of the truer 10 is fed in as shown by the arrow. (Step 1') The upper side width X1 of the truer 10 is created. (Step 2') The upper tip radius R1 of the truer 10 is created. (Step 3') The diameter D of the truer 10 is created. ｔ (Step 4') The lower tip radius R2 of the truer 10 is prepared. (Step 5') The lower side width X2 of the truer 10 is prepared. (Step 6') The shape of the lower side width X2 is adjusted and corrected. (Step 7') The lower tip radius R2, the diameter D ｔ The upper tip radius R1 and the upper side width X1 are adjusted and corrected (Step 8'). Steps 1' to 6' are repeated several times to create and finish the edge shape of the truer 10.

[0066] As described above, when manufacturing the edge shape of the truer 10 using the truer processing program 50, if a large number of wafers W are continuously machined using a specific portion of the grinding groove of the truer manufacturing grindstone 15, this specific portion will become deformed due to wear, etc., and it will no longer be possible to maintain the allowable shape accuracy of the truer 10 and the allowable shape accuracy of the wafers W, and the truer manufacturing grindstone 15 will reach the end of its service life beyond its usable limit.

[0067] However, the areas other than the worn portions remain usable. Therefore, the truer machining program 50 does not always machine the truer 10 using the same procedure, but instead varies the procedure to prevent uneven wear, thereby maximizing the life of the truer manufacturing grindstone 15. For example, if the procedure shown in FIG. 13 is normally performed and it is determined that the R1 and R2 portions of the truer manufacturing grindstone 15 (see FIG. 4) are deformed due to wear or other factors, steps (1) to (8) of FIG. 13 can be performed without steps (2) and (6), and CX1 and CX2 can be used instead of steps (2) and (6) to create R1 and R2 as shown in FIG. 11. Alternatively, as shown in the enlarged view of part A in FIG. 5 and FIG. 15, the truer 10 can be rotated around the pitch axis as indicated by the arrow, and R1 and R2 at the tip of the truer 10 can be pressed against the portion indicated by symbol e on the truer manufacturing grindstone 15, and grinding can be performed as shown in FIG. 11 to create R1 and R2. Here, in Fig. 5, the portion indicated by e in the enlarged view of part A is the tip surface of the convex portion of the truer manufacturing grinding stone 15. Fig. 15 is an explanatory diagram showing the state in which the R2 portion of the truer 10 is pressed against and ground at part e, which is the tip surface of the convex portion of the truer manufacturing grinding stone 15. Note that both Fig. 5 and Fig. 15 are explanatory diagrams, and are shown in shapes that differ from the actual dimensions and proportions for ease of viewing.

[0068] The prediction and identification of uneven wear areas of the truer-made grinding wheel 15 are performed by evaluation in the truer-made grinding wheel evaluation unit 39 based on a learning model 38 constructed from a processing condition database 37 that associates the processing conditions under which the processing load is monitored with the shapes of the truer 10 and grinding wheel 16 after processing.

[0069] The edge shape of the truer 10 is produced by the truer manufacturing grindstone 15 based on the truer processing program 50, so the life of the truer manufacturing grindstone 15 can be maximized by creating and updating the truer processing program 50 based on evaluation in the truer manufacturing grindstone evaluation unit 39.

[0070] DESCRIPTION OF SYMBOLS 10...Trua 15...Trua-prepared grinding wheel 16...Grinding wheel 17...Grinding wheel spindle 18...Quill 19...Second Truea-prepared grinding wheel 24...Workpiece fixing section 25...Workpiece moving table 25-1...Workpiece moving table 25-2...Moving table 30...Control section 35...Shape measuring section 37...Processing condition database 38...Learning model 38-1...Processing learning model 38-2...Analysis-based processing model 39...Trua-prepared grinding wheel evaluation section 50...Trua processing program W...Wafer

Claims

1. A wafer chamfering device that uses a truer to true a grinding wheel and grinds the outer peripheral edge of a wafer using the trued grinding wheel, comprising: a truer-making grinding wheel that makes the edge shape of the truer in accordance with a truer processing program; a control unit that controls the processing conditions of the truer-making grinding wheel, the truer, and the grinding wheel; and a truer-making grinding wheel evaluation unit that measures the edge shape of the truer and evaluates the truer-making grinding wheel, and creates and updates the truer processing program based on the evaluation.

2. A wafer chamfering device as described in claim 1, comprising: a shape measurement unit that measures the cross-sectional shape of the wafer; a processing condition database in which the shape of the wafer processed by the grinding wheel is measured by the shape measurement unit, compared with a target shape, and stored in association with processing conditions; and a learning model constructed from the processing condition database, wherein the Truer manufacturing grinding wheel evaluation unit evaluates the Truer manufacturing grinding wheel based on the learning model.

3. A wafer chamfering device as described in claim 1 or claim 2, characterized in that the truer manufacturing grinding wheel evaluation unit updates the truer processing program when it evaluates that the truer manufacturing grinding wheel has been deformed due to wear.

4. A wafer chamfering device according to claim 1 or 2, characterized in that the truer processing program is created by combining the tool path of the truer making grindstone with both down-cutting and up-cutting.

5. The edge shape of the truer is created by moving the workpiece fixing part of the truer in the X-axis, Y-axis, and Z-axis directions and rotating the truer along the rotation axis (θ ｗ 3. The wafer chamfering device according to claim 1, wherein grinding is performed by rotating the wafer about the pitch axis.

6. A wafer chamfering device according to claim 1 or 2, characterized in that the truer processing program is updated by changing the processing procedure of the truer.

7. A wafer chamfering device as described in claim 3, characterized in that the Truer manufacturing grindstone evaluation unit monitors the processing load to predict and identify uneven wear areas of the Truer manufacturing grindstone and reflects this in the Truer processing program.

8. The wafer chamfering device according to claim 3, wherein a motion program for uniformizing the processing use portion of the truer making grindstone is incorporated into the truer processing program.

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