Wafer chamfering device and chamfering method

Abstract

A wafer chamfering device includes a crystal orientation measuring instrument (24) for measuring the crystal orientation of the wafer, and repeatedly grinding the edge of the wafer until the alignment mark of the wafer and the consistency of the crystal orientation meet a specified reference.

Description

Technical Field

[0001] This disclosure relates to chamfering devices and chamfering methods. Background Technology

[0002] The edges of a wafer are marked with alignment marks for positioning during processing steps. These marks include orientation planes and notches. In this specification, these marks are collectively referred to as alignment marks. In single-crystal wafers, alignment marks also function as references for indicating crystal orientation.

[0003] A single-crystal wafer is a wafer that should be composed entirely of a single crystal. However, at the wafer edges, also known as the edge portion, the crystal structure may sometimes be incomplete due to differences in cooling rates during crystal growth and machining processes. In the primary applications of single-crystal wafers, even in a small portion, disordered crystal structure is undesirable. Disordered crystal structure increases the risk of insulation breakdown. Therefore, the general manufacturing process of wafers, represented by single-crystal wafers, includes a chamfering step, which involves grinding the entire circumference of the edge, including the portion with alignment marks. Furthermore, chamfering is expected to prevent chipping or breakage. Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-170312 Summary of the Invention The technical problem to be solved by the invention

[0005] The chamfering conditions must also be set considering the grinding of the portion with alignment marks. Therefore, information related to the wafer shape, such as the position of the alignment marks, is obtained using photoelectric sensors and used for condition setting (Patent Document 1). Chamfering is typically performed by bringing a grinding stone against the wafer held on the grinding table. In this case, grinding conditions include, for example, the approach angle of the grinding stone relative to the wafer, the movement speed of the grinding table, the rotational speed of the grinding stone and the grinding table, and the relative position of the grinding stone and the grinding table.

[0006] Alignment marks are required to function as markers corresponding to any crystal orientation in a single-crystal wafer. Alignment marks are typically set before chamfering. Ideally, alignment marks should align with or form a specified angle with a given crystal orientation. This is referred to in this specification as "ensuring alignment mark consistency with crystal orientation." Furthermore, the consistency between alignment mark and crystal orientation is sometimes simply referred to as "consistency."

[0007] However, the wafers before chamfering are mostly not guaranteed to be consistent. Therefore, chamfering not only involves grinding the edges of the wafer, but also requires adjusting the relationship between the alignment marks and the crystal orientation. In other words, chamfering also requires considering the relationship with the crystal orientation to adjust the shape and position of the alignment marks. Furthermore, in this specification, the state of not ensuring consistency is sometimes referred to as "inconsistency".

[0008] However, the inventors have discovered that wafer W, after beveling using conventional methods, also exhibits inconsistencies in terms of the generation or residue.

[0009] In addition to silicon (Si), wafers made of materials such as sapphire, gallium arsenide (GaAs), indium phosphide (InP), and silicon carbide (SiC) are increasingly required in applications such as optics, high-speed electronic devices, and power components. These single-crystal wafers are more expensive than traditional ones, thus necessitating higher yields. Therefore, even a single experimental wafer should not be wasted. This is one of the technical challenges of traditional methods.

[0010] The inventors believe that inconsistencies after chamfering may have other causes besides those before chamfering, and therefore conducted research. As mentioned above, conventional wisdom dictates that grinding conditions that eliminate inconsistencies before chamfering within the same batch can be used to remove systematic errors, thereby obtaining wafers of sufficiently high quality, making further investigation difficult. However, in-depth investigation revealed new causes of inconsistencies after chamfering.

[0011] The reason is as follows: When determining the crystal orientation of the test wafer, acquiring shape-related information, and during grinding, if the test wafer is placed on different stages, occasional errors (random errors) related to the wafer's position will occur. These errors may include wafer transfer errors between the measurement stage and the transport mechanism, transport errors of the transport mechanism, and wafer transfer errors between the transport mechanism and the grinding stage. Furthermore, random errors also exist in the measurement of the crystal orientation measuring instrument, and the inventors have discovered the cause of this. Conventional methods have not considered the existence of these random errors and their correction; therefore, even within the same batch, unpredictable inconsistencies can occur, and this problem remains unresolved.

[0012] This disclosure can solve at least one of the technical problems of the prior art described above. This disclosure can provide a chamfering apparatus capable of solving the problem of misalignment between alignment marks and crystal orientation. Furthermore, this disclosure can provide a chamfering method capable of solving the problem of misalignment between alignment marks and crystal orientation. Technical solutions to solve technical problems

[0013] The first chamfering device disclosed herein is a wafer chamfering device, which includes a crystal orientation measuring instrument for measuring the crystal orientation of the wafer, and repeatedly grinds the edge of the wafer until the alignment mark of the wafer and the crystal orientation meet a specified reference.

[0014] The second chamfering apparatus disclosed herein, like the first chamfering apparatus, includes a sensor for measuring the position of the alignment mark, and for the wafer held on the same measuring stage, measures the crystal orientation and the position of the alignment mark respectively.

[0015] The third chamfering apparatus disclosed herein, like the second chamfering apparatus, includes a conveying mechanism for translating the measuring stage, the conveying mechanism moving the measuring stage to a first position for measuring the position of the alignment mark and a second position for measuring the crystal orientation.

[0016] The fourth chamfering device disclosed herein is similar to the third chamfering device, wherein the measuring stage rotates in the second position in such a manner that the alignment mark is oriented toward the crystal orientation measuring instrument, based on the measurement result of the position of the alignment mark.

[0017] The fifth chamfering device disclosed herein is similar to the third chamfering device, wherein the sensor measures the size of the wafer, and the conveying mechanism adjusts the amount of translational movement of the measuring stage from the first position to the second position according to the size.

[0018] The sixth chamfering apparatus disclosed herein is similar to the third chamfering apparatus, wherein the conveying mechanism moves the measuring stage to a third position for grinding the wafer.

[0019] The first chamfering method disclosed herein is a wafer chamfering method using a chamfering apparatus equipped with a crystal orientation measuring device for determining the crystal orientation of the wafer. The chamfering method includes the step of repeatedly grinding the edge of the wafer until the alignment marks of the wafer and the consistency of the crystal orientation meet a predetermined reference.

[0020] The second chamfering method disclosed herein is similar to the first chamfering method, wherein the chamfering device includes a sensor for determining the position of the alignment mark, and the chamfering method includes the steps of determining the crystal orientation and the position of the alignment mark for the wafer held on the same measuring stage. Invention Effects

[0021] This disclosure can solve at least one of the technical problems of the prior art described above. This disclosure can provide a chamfering apparatus capable of solving the problem of misalignment between alignment marks and crystal orientation. Furthermore, this disclosure can provide a chamfering method capable of solving the problem of misalignment between alignment marks and crystal orientation. Attached Figure Description

[0022] Figure 1 This is a hardware configuration diagram of the chamfering device in Embodiment 1. Figure 2 This is a schematic top view of the main part of the chamfering device in Embodiment 1. Figure 3 This is a front view of the crystal orientation measuring section and the measuring section of the chamfering device in Example 1. Figure 4 This is a side view of the grinding section of the chamfering device in Embodiment 1. Figure 5 This is a flowchart of the chamfering method performed by the chamfering device in Embodiment 1. Figure 6A This is an explanatory diagram illustrating how to adjust the rotation angle of the measuring stage. Figure 6B This is an explanatory diagram illustrating how to adjust the rotation angle of the measuring stage. Figure 6C This is an explanatory diagram illustrating how to adjust the rotation angle of the measuring stage. Figure 6D This is an explanatory diagram illustrating how to adjust the rotation angle of the measuring stage. Figure 7 This is an explanatory diagram illustrating information related to the consistency of alignment marks and crystal orientation. Figure 8 This is a hardware configuration diagram of the chamfering device in Embodiment 2. Figure 9 This is a schematic top view of the main part of the chamfering device in Embodiment 2. Detailed Implementation

[0023] Figure 1 This is a hardware configuration diagram of the chamfering device 10 in Embodiment 1. Figure 2 This is a schematic top view of the main part of the chamfering device 10. Figure 3 This is a front view of the crystal orientation measuring section 10-3 and measuring section 10-2 of the chamfering device 10. Furthermore, Figure 4 This is a side view of the grinding section 10-1 of the chamfering device 10.

[0024] The chamfering device 10 includes a controller 12, a grinding section 10-1, a measuring section 10-2, a crystal orientation measuring section 10-3, a first conveying mechanism 10-5, a second conveying mechanism 10-4, a storage section 10-6, and a measuring stage 20. In addition to the above, the chamfering device 10 may further include a cleaning / drying section for cleaning and drying the wafer W.

[0025] The controller 12 controls each part of the chamfering device 10. The controller 12 is a computer comprising a processor and memory. The memory stores pre-installed programs (instruction sets) for controlling each part. The processor executes the commands contained in the program and controls each part of the chamfering device 10. Furthermore, the controller 12 may include a touch-sensitive display or the like as an input / output interface.

[0026] The grinding unit 10-1 includes grinding stones 51 and 52. The grinding unit 10-1 uses grinding stones 51 and 52 to chamfer the wafer W held on the grinding table 50. Specifically, the grinding stones 51 and 52 and the wafer W rotate relative to each other while abutting. Furthermore, the number of grinding stones in the grinding unit 10-1 does not need to be two; it can be one or more than three. The number of grinding stones can be appropriately selected based on the chamfering method, etc.

[0027] The grinding table 50 is a disk-shaped device with a diameter smaller than that of the wafer W. The grinding table 50 holds the wafer W using depressurized suction. The grinding table 50 is rotatably supported by a spindle motor 53. Under the control of the controller 12, the grinding table 50 can rotate according to predetermined grinding conditions. The held wafer W can also rotate together with the grinding table 50.

[0028] Furthermore, the grinding table 50 is connected to a position adjustment mechanism (not shown in the figure). The position adjustment mechanism can translate the grinding table 50 according to the grinding conditions. This position adjustment mechanism is known technology; for example, paragraphs 0013 to 0019 of European Patent Application Publication No. 962282 (EP0962282(A1)) can be cited as examples. Figures 1 to 3 The contents described herein are incorporated herein by reference. Furthermore, the third position Pos-3 for grinding is the initial position for grinding. During chamfering, the position of the grinding table 50 can be appropriately adjusted by the position adjustment mechanism.

[0029] Grinding stones 51 and 52 are rotatably supported by spindle motors 54 and 55, respectively. Figure 4 Furthermore, spindle motors 54 and 55 are fixed to a support platform (not shown) in a vertically movable manner. This support platform is known technology; for example, paragraphs 0020 to 0021 of European Patent Application Publication No. 962282 (EP0962282(A1)) can be cited. Figure 1 The contents described herein are incorporated herein by reference.

[0030] Grinding stones 51 and 52 are both disc-shaped. Grinding grooves are provided on the outer periphery of grinding stones 51 and 52. These grooves abut against the edge (edge ​​portion) of the wafer W and chamfer it. Furthermore, grinding stone 51 is used for rough grinding (one-pass grinding) of the wafer W. The type of grinding stone is not particularly limited; metal-bonded grinding stones, where abrasive grains made of metal and / or inorganic compounds are held together by a metal-based binder, can be used. On the other hand, grinding stone 52 can have a smaller diameter than the wafer W. Grinding stone 52 is used for fine grinding (finishing grinding) of the wafer W. The type of grinding stone is also not particularly limited; resin-bonded grinding stones, etc., using resin as a binder, can be used. The rotation axis of grinding stone 52 can be tilted approximately 3 to 10° relative to the rotation axis of the wafer W. The technique of tilting the rotation axis and performing grinding is called "spiral grinding." Spiral grinding can improve the shape accuracy and surface finish of the wafer W after processing.

[0031] The measurement unit 10-2 includes a sensor unit 40. The sensor unit 40 comprises a laser sensor, a capacitance sensor, an air micro-sensor, an image sensor, and a photoelectric sensor. The sensor unit 40 can acquire information related to the shape of the wafer W, such as its size, thickness, eccentricity, and the position of the alignment mark AM, held on the measurement stage 20. In particular, the photoelectric sensor can be a sensor that illuminates the wafer W and receives the reflected light (reflective type), or a sensor that illuminates the wafer W and detects light path obstruction caused by the wafer W (transmissive type), thereby enabling more accurate acquisition of information related to the shape of the wafer W.

[0032] When the measuring stage 20 is in the first position Pos-1, the measuring unit 10-2 measures the wafer W. If the measuring stage 20 is in the first position Pos-1, the measurement timing can be appropriately selected. For example, the measurement timing could be after the first transport mechanism 10-5 has transferred the wafer W to the measuring stage 20 and before the measuring stage 20 is moved from the first position Pos-1 by the second transport mechanism 10-4, or before the first transport mechanism 10-5 receives the wafer W from the measuring stage 20. Preferably, the measurement is performed at least after the first transport mechanism 10-5 has transferred the wafer W to the measuring stage 20 and before the measuring stage 20 moves from the first position Pos-1. Furthermore, the sequence related to the movement of the measuring stage 20 is described below.

[0033] The crystal orientation measuring unit 10-3 includes a crystal orientation measuring device 24 based on X-ray diffraction. The crystal orientation measuring device 24 includes an X-ray generating unit 28 and an X-ray detecting unit 29. When the measuring stage 20 is in the second position Pos-2, the crystal orientation measuring device 24 irradiates X-rays near the alignment mark on the wafer W and detects the diffracted X-rays. The posture of the X-ray generating unit 28 and the X-ray detecting unit 29 can be adjusted by a posture adjustment mechanism not shown in the figure. Alternatively, it can be fixed according to the material of the wafer W, the relationship between the alignment mark AM and the crystal orientation. For example, when the orientation plane is set parallel to the (011) plane of the gallium arsenide wafer, the diffraction angle is 2θ = 45°. The incident angle and detection position can be adjusted accordingly.

[0034] The crystal orientation measuring unit 10-3 may further include a sensor unit 27. The sensor unit 27 may include the same sensor group as the sensor unit 40. Preferably, it includes a reflective photoelectric sensor. The sensor unit 27 can acquire shape-related information about the wafer on the measuring stage 20, which has moved to the second position Pos-2. Preferably, it detects the position of the alignment mark AM.

[0035] Furthermore, the crystal orientation measurement unit 10-3 may not include the sensor unit 27. Details are described below, but after the measurement is performed by the measurement unit 10-2, the rotation angle of the measurement stage 20 can be controlled to orient the alignment mark AM in a predetermined direction. Therefore, the crystal orientation can be determined even without re-measuring the orientation of the alignment mark AM on the transported wafer W. To detect the alignment mark AM, for example, the wafer W needs to be rotated once. Therefore, by avoiding repeated measurement of the alignment mark AM by the crystal orientation measurement unit 10-3, the entire process flow can be shortened.

[0036] The second conveying mechanism 10-4 moves the measuring stage 20 between a first position Pos-1 and a second position Pos-2. The first position Pos-1 is the measuring position of the measuring unit 10-2. The second position Pos-2 is the measuring position of the crystal orientation measuring unit 10-3. In other words, the second conveying mechanism 10-4 is a hardware assembly that has the function of sharing the measuring stage 20 between the measuring unit 10-2 and the crystal orientation measuring unit 10-3.

[0037] The measuring stage 20 is a disk-shaped support stage with a diameter smaller than that of the wafer W. The measuring stage 20 holds the wafer W. There is no particular limitation on the holding method; a method of holding by depressurized adsorption can be cited as an example. The measuring stage 20 can be rotated by a spindle motor 21 around a rotation axis parallel to the Z-axis.

[0038] according to Figure 3The second conveying mechanism 10-4 and its relationship with other parts are explained. The second conveying mechanism 10-4 includes a guide rail 23A, a ball screw 23B, a stepper motor 23C, and a linear slide rail 22, all fixed to the main body base 26. The actuator of the second conveying mechanism 10-4 is represented as a combination of the ball screw 23B and the stepper motor 23C, but it is not limited to this structure; servo motors or linear motors, etc., can be used as appropriate.

[0039] The ball screw 23B is driven to rotate by the stepper motor 23C. The rotation of the ball screw 23B causes the linear slide rail 22 to translate along the guide rail 23A (in the direction of arrow Ar-1). The measuring stage 20 is fixed within the linear slide rail 22 by the spindle motor 21. Therefore, the measuring stage 20 also translates along the guide rail 23A. The spindle motor 21 drives the measuring stage 20 to rotate around a rotation axis parallel to the Z-axis. These mechanisms enable the measuring stage 20 to translate and rotate. The translation and rotation of the measuring stage 20 are controlled by the controller 12.

[0040] The crystal orientation measuring device 24 is fixed on the stand 25. The stand 25 is connected to the main base 26. The second conveying mechanism 10-4 can move the wafer W received by the first conveying mechanism 10-5 to the second position Pos-2 from the first position Pos-1. Furthermore, the wafer W after measurement can be moved from the second position Pos-2 to the first position Pos-1, making it ready to be received by the first conveying mechanism 10-5. By separately setting the measurement positions of the measuring unit 10-2 and the crystal orientation measuring unit 10-3, the flexibility of device configuration can be further improved. In particular, since the crystal orientation measuring device 24 operates on the principle of X-ray diffraction, shielding mechanisms are sometimes used. By separating the crystal orientation measuring unit 10-3 from the measuring unit 10-2, the configuration of the shielding mechanism becomes easier. Furthermore, upgrading conventional chamfering devices is also simpler. Conventional chamfering devices do not have a crystal orientation measuring unit 10-3. However, by adding a second conveying mechanism 10-4, a crystal orientation measuring unit 10-3 can be easily added. This is one of the advantages of separately setting the measuring positions of the measuring unit 10-2 and the crystal orientation measuring unit 10-3. Furthermore, as will be described later, this is also advantageous in terms of measuring crystal orientation for wafers of various sizes.

[0041] Furthermore, in this embodiment, the sensor unit 40 is independent of the measuring stage 20 and fixed to the measuring unit 10-2. However, it can also be configured such that the sensor unit 40 is fixed to the linear slide rail 22 and moves together with the measuring unit 10-2 toward the crystal orientation measuring unit 10-3.

[0042] The first conveying mechanism 10-5 includes a rotatable and translatable arm 71. The arm 71 can remove the wafer W from the wafer cassette 70 of the storage section 10-6, transfer the wafer W between the measuring stage 20 and the grinding stage 50.

[0043] Arm 71 can be, for example, a 3-axis rotating arm. Furthermore, arm 71 may further include an adsorption pad for securing the wafer W. In this case, the adsorption pad can be brought into contact with the back of the wafer W and depressurized adsorption can be performed. Arm 71 can move back and forth, move up and down, and rotate while holding the wafer W. By combining these actions, wafer W can be removed from wafer cassette 70, wafer W can be stored in wafer cassette 70, and wafer W can be transferred between different stations. Furthermore, the first conveying mechanism 10-5 is controlled by controller 12.

[0044] Next, the chamfering method using chamfering device 10 will be explained. Figure 5 This is a flowchart of the chamfering method.

[0045] First, in step S10, the measuring unit 10-2 measures shape-related information of the wafer W placed on the measuring stage 20. Specifically, this may include the size, thickness, eccentricity relative to the center of the measuring stage 20, and position of the alignment mark of the wafer W. The shape-related information of the wafer W includes at least the position of the alignment mark. Furthermore, the wafer W may be a wafer removed from the wafer cassette 70 of the receiving unit 10-6 by the first transport mechanism 10-5 before the actual steps begin. The first transport mechanism 10-5 transfers the removed wafer W to the measuring stage 20.

[0046] Next, in step S11, the measuring stage 20 (and the wafer W) are conveyed to the crystal orientation measuring unit 10-3 by the second conveying mechanism 10-4. At this time, the wafer W is adjusted to face a predetermined direction on the measuring stage 20. Specifically, the rotation angle of the measuring stage 20 is adjusted so that the alignment mark faces the crystal orientation measuring device 24 according to shape-related information.

[0047] Figures 6A to 6D This is an explanatory diagram illustrating the method for adjusting the rotation angle of the measuring stage 20 using a top view of the second conveying mechanism 10-4. Figure 6A This indicates the state after the shape-related information is acquired by the measuring unit 10-2. At this time, the measuring stage 20 is located at the first position Pos-1. The wafer W is fixed on the measuring stage 20. The alignment mark AM is facing a certain direction. Furthermore, more specifically, the first position Pos-1 can be defined as the center position of the measuring stage 20 when acquiring shape information.

[0048] Next, the measuring stage 20 is rotated so that the alignment mark AM is oriented towards the measuring position Pos-X of the crystal orientation measuring instrument 24. The rotation amount (rotation angle) of the measuring stage 20 is controlled according to the eccentricity of the wafer W, the position of the alignment mark AM, and the direction of the measuring position Pos-X. Figure 6A In the middle, the measuring stage 20 is rotated in the direction of arrow Ar-3. After rotation, it is adjusted, for example, so that the alignment mark AM (X1 axis) is parallel to the X2 axis. Figure 6B This indicates the state of the wafer after rotation. Furthermore, the X1 and X2 axes do not necessarily need to be aligned parallel. It is preferable to adjust them in a way that makes the included angles between these axes within a certain range. The reasons are as follows.

[0049] The X2 axis is perpendicular to the Y1 axis, the moving axis of the measuring stage 20, and their intersection is the measuring position Pos-X. The second position Pos-2 is the position of the measuring stage 20 when measured by the crystal orientation measuring instrument 24. The second position Pos-2 is defined as the center position of the measuring stage 20. The second position Pos-2 is determined according to the measuring position Pos-X, the size of the wafer W, and the amount of eccentricity.

[0050] Next, the measuring stage 20 is moved along the Y1 axis in the direction of arrow Ar-4. The amount of movement is enough to align the X1 and X2 axes. In other words, it is enough to bring the alignment mark AM to the measuring position Pos-X. Therefore, it is not necessary to align the wafer W before crystal orientation measurement. This is because, based on the information obtained by the measuring unit 10-2, the rotation angle of the measuring stage 20 is pre-set to be suitable for crystal orientation measurement.

[0051] Figure 6C This indicates that the measuring stage 20 is in the second position Pos-2. The alignment mark AM was adjusted in the previous step to face the crystal orientation measuring device 24 (measuring position Pos-X), so the measuring stage 20 only needs to be moved a predetermined amount along the Y1 axis. This aligns the X1 and X2 axes. In other words, the alignment mark AM is located at the measuring position Pos-X of the crystal orientation measuring device 24. Furthermore, the position of the measuring stage 20 (second position Pos-2) is adjusted according to the size of the wafer W and the wafer's eccentricity.

[0052] Figure 6D This indicates that the measuring stage 20, on which the larger diameter wafer W2 is mounted, is in the second position, Pos-2. Figure 6C Similarly, the alignment mark AM is located at the measurement position Pos-X of the crystal orientation measuring instrument 24. At this time, the center of the measuring stage 20 is located on the Y1 axis, which is consistent with... Figure 6CThe measurements are the same, but in different positions. Specifically, the center of the measuring stage 20 is moved to the right of the Y1 axis by a distance corresponding to the radius difference of the wafer W. The figure shows the case without eccentricity, but the amount of eccentricity must be considered further.

[0053] By constructing the chamfering device 10 as described above, and especially by constructing the second conveying mechanism 10-4 and the measuring stage 20 supported thereon, the crystal orientation of wafers W of various sizes can be easily measured. In other words, since the chamfering device 10 has the second conveying mechanism 10-4, the crystal orientation can be measured regardless of the size of the wafer W.

[0054] Furthermore, by using the shape-related information obtained from the measuring unit 10-2, the measuring stage 20 is rotated only to position the alignment mark AM relative to the measuring position Pos-X, thus minimizing deviations in the relationship between the alignment mark AM and the measuring position Pos-X. While some methods use fixtures for positioning, this is also one of the causes of random errors in crystal orientation measurements. The chamfering device 10 positions the alignment mark AM relative to the measuring position Pos-X in a non-contact manner, thus suppressing the generation of random errors.

[0055] Furthermore, it is also important that the measurement stage 20 can be shared in both shape-related information acquisition and crystal orientation determination. Sharing the measurement stage 20 can eliminate the influence of wafer W junction or setup errors of different devices. By sharing the measurement stage 20 in both shape-related information acquisition and crystal orientation determination, the relationship between the alignment mark AM and the crystal orientation can be obtained with high precision.

[0056] Furthermore, the above is an example where it is not necessary to align the X1 and X2 axes before starting the crystal orientation measurement. As explained in the following steps, the wafer W can be rotated during the measurement. Therefore, the rotation angle can be considered, and the crystal orientation measurement can begin when the X1 and X2 axes form a certain angle. Generally, the angle of inconsistency is usually less than 10°. Therefore, this can also be considered when setting the angle between the X1 and X2 axes at the start of the crystal orientation measurement.

[0057] Back Figure 5 The flowchart shows that if wafer W is transported to the crystal orientation determination unit 10-3, the crystal orientation is determined in step S12. This obtains information about the consistency between the alignment mark AM and the crystal orientation. The crystal orientation is determined while wafer W is rotated. The intensity change of diffracted X-rays is detected while wafer W is rotated.

[0058] Figure 7 A diagram illustrating information related to the alignment of the AM marker with the crystal orientation. Figure 7This is an explanatory diagram using a top view of wafer W. The following explains the case where the alignment mark AM should ideally align with a certain crystal plane MP. If the alignment mark AM aligns with the crystal plane MP, then when X-rays are incident on the alignment mark AM from the X-ray generating unit 28 at a predetermined angle, stronger diffracted X-rays will be detected through Bragg reflection. Figure 7 In this case, the crystal plane MP deviates from the alignment mark AM by an angle θC. Angle θC can be determined based on the rotation angle of the wafer W and the intensity variation of the diffracted X-rays. This angle θC can represent information indicating the consistency between the alignment mark AM and the crystal orientation. Furthermore, the alignment mark AM and the crystal plane MP do not necessarily need to be aligned. For example, there are cases where the alignment mark AM and the crystal plane MP form a predetermined angle. In this case, the information indicating the consistency between the alignment mark AM and the crystal orientation can be the deviation (angle) of the crystal plane MP based on that angle.

[0059] Next, in step S13, the wafer W is transferred to the grinding section 10-1. Specifically, the first transfer mechanism 10-5 first receives the wafer W from the measuring stage 20. Then, the wafer is moved towards arrow Ar-2 by the rotation and translation of the arm 71. Figure 2 The grinding table 50 then moves in the following direction. Afterwards, the grinding table 50 receives the wafer W from the first conveyor mechanism 10-5.

[0060] The shape-related information of the wafer W measured in step S10 (especially the position of the alignment mark AM in the rotation direction of the measuring stage 20) can be maintained after the wafer W moves to the grinding stage 50. In other words, the wafer W moves towards the measuring stage 20, the first transport mechanism 10-5, and the grinding stage 50 based on the position information of the alignment mark AM. That is, the position information of the alignment mark AM can be maintained during the movement from the measuring stage 20 to the grinding stage 50.

[0061] Next, in step S14, the edge (edge ​​portion) of the wafer W on the grinding table 50 is ground (beveled). The grinding conditions are set according to the relationship between the alignment mark AM and the crystal orientation. That is, the shape of the alignment mark AM is corrected in a way that corrects the inconsistency between the alignment mark AM and the crystal orientation. Furthermore, the grinding method including the edge portion of the alignment mark AM is not particularly limited, and known methods can be applied. For example, paragraphs 0029 to 0039, paragraphs 0044 to 0057 of European Patent Application Publication No. 962282 (EP0962282(A1)) can be cited. Figure 4 (a) to Figure 4 (f) Figure 5 (a) to Figure 5 (e). This specification incorporates by reference the description in the aforementioned application specification.

[0062] Next, in step S15, the chamfered wafer W is transferred to the measurement unit. Specifically, the first transfer mechanism 10-5 first receives the wafer W from the grinding table 50. Then, the wafer is moved towards arrow Ar-2 by the rotation and translation of the arm 71. Figure 2 The wafer moves in the following direction. Afterwards, the measuring stage 20 receives the wafer W from the first conveying mechanism 10-5. During this movement, the position information of the alignment mark AM may not be maintained. The actual shape of the alignment mark AM may also change due to the chamfering. On the other hand, the position information of the alignment mark AM can also be maintained. In practical applications, the deviation of the alignment mark AM from the specified crystal orientation is mostly less than 10°. Therefore, significant changes in the shape of the wafer after chamfering are rare. That is, the new alignment mark AM after chamfering is mostly located in almost the same position as the (old) alignment mark AM before chamfering.

[0063] In this case, when the chamfered part is transferred to the measuring stage 20, the positional information of the initial alignment mark AM can be maintained, which can sometimes make subsequent steps more efficient. That is, when detecting the alignment mark AM in subsequent steps, the approximate position of the new alignment mark AM can be determined based on the positional information of the initial alignment mark AM, thus enabling efficient measurement.

[0064] Next, in step S16, the shape-related information of the wafer W placed on the measurement stage 20 is measured by the measurement unit 10-2. The measurement method can be the same as in step S10. On the other hand, in actual steps, as long as at least the eccentricity of the wafer W relative to the center of the measurement stage 20 and the position of the alignment mark AM are measured, other measurements can be omitted. Specifically, measurements such as the size and thickness of the wafer W can be omitted. By omitting these measurements, the process flow can be made faster. The shape-related information of the wafer W is stored in the memory of the controller 12. At this time, as the shape-related information of the wafer W, at least the eccentricity relative to the center of the measurement stage 20 and the position of the alignment mark can be updated in the information already stored in the memory. The information before the update is sometimes the information stored in step S10, and sometimes the information stored in step S16 after the second update. In addition, the information before the update can also be stored separately in the memory.

[0065] Next, in step S17, the measuring stage 20 (and the wafer W) are transported to the crystal orientation measuring unit 10-3 via the second conveying mechanism 10-4. At this time, the wafer W is adjusted to face a predetermined direction on the measuring stage 20. Specifically, the rotation angle of the measuring stage 20 is adjusted so that the alignment mark AM faces the crystal orientation measuring instrument 24, based on the updated shape-related information. The conveying method can be the same as in step S11.

[0066] Next, in step S18, the crystal orientation is determined. Information regarding the consistency between the alignment mark AM and the crystal orientation is obtained. This information is stored in the memory of the controller 12. At this time, the consistency information stored in the memory can be updated. The information before the update is sometimes the information stored in step S12, and sometimes the information stored in subsequent steps S18. Furthermore, the information before the update can also be additionally stored in the memory.

[0067] Next, in step S19, it is determined whether the consistency between the alignment mark AM and the crystal orientation meets the prescribed criteria. The processor executes the program stored in memory and performs the determination. The criteria may be, for example,... Figure 7 The allowable range of angle θC is the angle between the alignment mark AM and any crystal plane (or a line forming a specified angle with the crystal plane). For example, an angle θC range of -0.05° to +0.05° can be given. Furthermore, the allowable range can be appropriately determined based on the required quality, etc.

[0068] When the judgment result indicates that the consistency between the alignment mark AM and the crystal orientation does not meet the benchmark (step S19: NO), repeat steps S13 to S19. In this case, there is no need to discard or replace wafer W. Traditional chamfering methods would replace (i.e., discard) the test wafer. However, this is not necessary in this method. As mentioned earlier, the purpose of traditional methods is to eliminate inconsistencies between the alignment mark AM and the crystal orientation within the same batch as systematic errors. Therefore, multiple test wafers are used to determine the grinding conditions.

[0069] This method is based on the discovery that random errors arising from setting wafers W on various stages can unpredictably produce inconsistencies in the beveled wafers. By discovering a cause of error that has not been explored in traditional methods, beveling can be performed efficiently even on expensive wafers.

[0070] On the other hand, when the determination result is that the consistency between the alignment mark AM and the crystal orientation meets the prescribed benchmark (step S19: YES), the chamfering ends. If the chamfering ends, in the next step S20, the first conveying mechanism 10-5 houses the wafer W into the housing section 10-6.

[0071] Next, other embodiments of the chamfering device will be described. Figure 8 This is a hardware configuration diagram of the chamfering device 11 in Embodiment 2. Furthermore, Figure 9 This is a schematic top view of the main part of the chamfering device 11.

[0072] The grinding section 11-1 of the chamfering device 11 does not have a grinding table 50. The second conveying mechanism 10-4 of the chamfering device 11 has a guide rail 23A that extends to a third position Pos-3 for grinding. One of the features of the chamfering device 11 is that it shares a table for acquiring shape-related information of the wafer W, determining crystal orientation, and grinding (chamfering). By sharing a table, the generation of setting errors, etc., during wafer W handover can be suppressed. Therefore, inconsistencies can be corrected with high precision or the generation of inconsistencies can be further suppressed.

[0073] The chamfering method in chamfering device 11 can be based on the following: Figure 5 The process follows a similar flowchart. (And...) Figure 5 The process differs in that the wafer W transport in step S13 can be performed by moving the second transport mechanism 10-4 in the direction of arrow Ar-3. Furthermore, in the following step S14, the wafer on the measuring stage 20 is ground by grinding stones 51 and 52.

[0074] Subsequent steps also omit the wafer W handover between the grinding stage 50 and the first transport mechanism 10-5. In other words, instead of this handover, the measuring stage 20 moves between the first position Pos-1, the second position Pos-2, and the third position Pos-3. If the chamfering device 11 is used, the error caused by the wafer W handover can be further suppressed, resulting in high-precision correction of inconsistencies or further suppression of inconsistencies in the wafer W after chamfering.

[0075] Furthermore, both Embodiment 1 (beveling device 10) and Embodiment 2 (beveling device 11) are equipped with a second conveying mechanism 10-4. However, even beveling devices without a second conveying mechanism 10-4 can correct inconsistencies. For example, a crystal orientation measuring device 24 can be placed near the measuring section 10-2. In this case, the wafer located at the second position Pos-2 is rotated appropriately, and the alignment mark AM is moved to the measuring position of the crystal orientation measuring device 24. That is, the alignment mark AM is oriented towards the crystal orientation measuring device 24 mainly by rotating the wafer W. As described above, this makes the overall beveling device more compact. Explanation of reference numerals in the attached figures

[0076] 10, 11: Chamfering device; 10-1: Grinding section; 10-2: Measuring section; 10-3: Crystal orientation measuring section; 10-4: Second conveying mechanism; 10-5: First conveying mechanism; 10-6: Storage section; 12: Controller; 20: Measuring table; 24: Crystal orientation measuring device; 50: Grinding table.

Claims

1. A wafer chamfering device, wherein, The chamfering device includes a crystal orientation measuring instrument for determining the crystal orientation of the wafer. The chamfering device repeatedly grinds the edge of the wafer until the alignment marks of the wafer and the consistency of the crystal orientation meet the specified benchmark.

2. The chamfering device according to claim 1, wherein, The chamfering device includes a sensor for determining the position of the alignment mark. Furthermore, for the wafers held on the same measuring stage, the crystal orientation and the position of the alignment marks are measured respectively.

3. The chamfering device according to claim 2, wherein, The chamfering device includes a conveying mechanism for translating the measuring stage. The conveying mechanism moves the measuring stage to a first position for measuring the position of the alignment mark and a second position for measuring the crystal orientation.

4. The chamfering device according to claim 3, wherein, The measuring stage rotates in the second position, in a manner that aligns the alignment mark toward the crystal orientation measuring instrument, based on the measurement result of the position of the alignment mark.

5. The chamfering device according to claim 3, wherein, The sensor measures the size of the wafer. The conveying mechanism adjusts the amount of translation of the measuring platform from the first position to the second position according to the size.

6. The chamfering device according to claim 3, wherein, The conveying mechanism moves the measuring stage to a third position for grinding the wafer.

7. A chamfering method, which is a chamfering method for wafers using a chamfering apparatus, wherein, The chamfering device includes a crystal orientation measuring instrument for determining the crystal orientation of the wafer. The chamfering method includes the step of repeatedly grinding the edge of the wafer until the alignment marks of the wafer and the consistency of the crystal orientation meet a specified benchmark.

8. The chamfering method according to claim 7, wherein, The chamfering device includes a sensor for determining the position of the alignment mark. The chamfering method includes the steps of determining the crystal orientation and the position of the alignment mark for the wafer held on the same measuring stage.

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