Detection method and processing device

Abstract

To provide a method for accurately detecting a center of a mark formed on a wafer and indicating a crystal orientation.SOLUTION: A detection method for detecting a mark 8 formed at an outer peripheral edge of a semiconductor wafer 1 and indicating a crystal orientation includes: a first rotation step S11 of relatively rotating measurement light and the semiconductor wafer 1, receiving the measurement light, which is transmitted through or reflected by the mark 8, and detecting that a received light intensity of the measurement light exceeds a maximum value and starts falling; a second rotation step S13 of relatively rotating the measurement light and the semiconductor wafer in reverse directions after the first rotation step S11 and receiving the measurement light which is transmitted through or reflected by the mark 8; a mark center detection step S14 of determining a region, in which the received light intensity of the measurement light becomes the maximum value in the first rotation step S11 or the second rotation step S13, as a center of the mark 8; and a second rotation stop step S15 of stopping the rotation in the center of the mark 8 after the second rotation step S13.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a detection method and processing apparatus for detecting a mark that indicates a crystal orientation formed on the outer peripheral edge of a semiconductor wafer. [Background technology]

[0002] Wafers made of semiconductor materials such as silicon have notches, orientation flats, or other notches formed on the periphery of the wafer as marks indicating the crystal orientation, and devices are formed in accordance with this crystal orientation.

[0003] Furthermore, in order to increase the number of devices that can be formed on the wafer surface compared to notches or orientation flats, a method has been devised in which a flat portion is formed on the chamfered portion on the outer periphery of the wafer as a mark indicating the crystal orientation (see Patent Document 1). These crystal orientation marks are used for alignment when processing wafers in the manufacturing process of semiconductor devices. For this alignment, a photoelectric sensor is typically used, and the crystal orientation is detected when the amount of transmitted or reflected light received exceeds a threshold value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2007-189093 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the mark indicating the crystal orientation has a certain width, the amount of light received exceeds the threshold just before the center of the flat portion when using the notch or orientation flat described above, which poses the problem that only rough alignment is possible.

[0006] To solve this problem, one method that has been considered is to reduce the error by setting the threshold value closer to the peak value of the received light intensity, but this method has the risk of causing detection errors due to changes in the photoelectric sensor over time, etc.

[0007] The present invention provides a method and processing apparatus for accurately detecting the center of a mark that indicates crystal orientation formed on a wafer. [Means for solving the problem]

[0008] The present invention provides A detection method for detecting a mark indicating a crystal orientation formed on an outer peripheral edge of a semiconductor wafer, comprising: a first rotation step of relatively rotating the measurement light and the semiconductor wafer around a rotation axis passing through the center of the semiconductor wafer while irradiating the outer peripheral edge of the semiconductor wafer with measurement light, receiving the measurement light transmitted through or reflected by the mark, and detecting when the received light intensity of the measurement light exceeds a maximum value and starts to decrease; a second rotation step in which, after the first rotation step, the measurement light and the semiconductor wafer are relatively rotated in a direction opposite to the direction of rotation in the first rotation step, and the measurement light transmitted through or reflected by the mark is received; a mark center detection step of determining a region where the received light intensity of the measurement light is maximum as the center of the mark in the first rotation step or the second rotation step; After the second rotation step, a rotation stopping step is provided in which the relative rotation between the semiconductor wafer and the measurement light is stopped at the center of the mark.

[0009] The present invention also provides A processing device for detecting a mark indicating a crystal orientation formed on an outer peripheral edge of a semiconductor wafer, a holding table for holding the semiconductor wafer; a crystal orientation detection sensor having a light projecting unit that projects measurement light onto the mark on the semiconductor wafer and a light receiving unit that receives measurement light reflected by or transmitted through the mark; a rotation drive unit that rotates the holding table and the crystal orientation detection sensor relative to each other around a rotation axis that passes through the center of the holding table; a control unit, The control unit a rotation direction control unit that controls the direction of the relative rotation; a rotation stop control unit that stops the relative rotation; a mark center detection unit that determines a region where the received light intensity of the measurement light is maximum as the center of the mark, the rotation direction control unit changes the rotation direction of the relative rotation after detecting that the received light intensity of the measurement light exceeds a maximum value and starts to decrease while rotating the relative rotation in a predetermined direction; The rotation stop control unit changes the direction of the relative rotation, and then stops the relative rotation at the center of the mark. [Effects of the Invention]

[0010] According to the present invention, the center of a mark that indicates a crystal orientation formed on a wafer can be accurately detected, thereby improving positioning accuracy. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of a semiconductor wafer 1 according to an embodiment. [Figure 2] FIG. 2 is a plan view of the semiconductor wafer 1 of FIG. 1 in which the semiconductor chips 3 are sectioned. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line BB in FIG. [Figure 5] FIG. 5 is a conceptual diagram of a processing device for detecting a mark indicating the crystal orientation of a semiconductor wafer 1 according to one embodiment of the present invention. [Figure 6] FIG. 6 is a flow diagram of the detection method according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing the positions of the measurement light and the marks in the detection steps (A) to (F) in the first embodiment. [Figure 8] FIG. 8 is a graph showing the received light intensity of reflected light in the detection steps (A) to (F) in the first embodiment. [Figure 9] FIG. 9 is a flow diagram of a detection method according to the second embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing the positions of the measurement light and the marks in the detection steps (A) to (F) in the second embodiment. [Figure 11] FIG. 11 is a diagram showing a graph of the measurement light in each of the steps (A) to (F) in the second embodiment. [Figure 12] FIG. 12 is a perspective view of the semiconductor wafer 1 of the first modified example. [Figure 13] FIG. 13 is a perspective view of a semiconductor wafer 1 according to a second modified example. [Figure 14] FIG. 14 is a conceptual diagram of a processing device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the detection method and processing apparatus of the present invention will be described with reference to the drawings.

[0013] First, a semiconductor wafer 1, which is the processing target of the detection method and processing apparatus of the present invention, will be described with reference to Figures 1 to 4. Figure 1 is a perspective view of a semiconductor wafer according to one embodiment, Figure 2 is a plan view of the semiconductor wafer of Figure 1 in which semiconductor chips are partitioned and formed, Figure 3 is a cross-sectional view taken along line AA in Figure 2, and Figure 4 is a cross-sectional view taken along line BB in Figure 2.

[0014] A semiconductor wafer 1 (hereinafter referred to as a wafer) is a disk-shaped wafer having a crystalline orientation, such as single-crystal silicon. The thickness of the wafer 1 is, for example, about 600 μm. As shown in FIG. 2, rectangular semiconductor chips (devices) 3 are partitioned on the surface of the wafer 1 by grid-like division lines 2. Electronic circuits are formed on the surfaces of these semiconductor chips 3.

[0015] The outer peripheral edge of the wafer 1 is chamfered from the front side to the back side, thereby forming a chamfered portion 7 with an arc-shaped or tapered cross section between the perfectly circular front edge 6a and back edge 6b. The formation of the chamfered portion 7 prevents cracks, chips, or dust from being generated by an inadvertent impact. The chamfered portion 7 does not need to be chamfered across the entire area from the front edge 6a to the back edge 6b; it may include a portion that is not chamfered, for example, an intermediate portion between the front edge 6a and the back edge 6b. Therefore, the chamfered portion 7 can be considered to be the area that overlaps with the chamfered area when viewed from a direction perpendicular to the surface direction of the wafer 1 (the parallel front and back surfaces).

[0016] As shown in FIGS. 1 and 2, a mark 8 indicating the crystal orientation is formed at a predetermined location on the chamfered portion 7. This mark 8 is a minute flat mirror surface 8A formed by cutting out a portion of the outermost peripheral edge of the chamfered portion 7 so as to form a flat surface. The minute flat mirror surface 8A is formed to indicate the crystal orientation at a position where the line connecting the center of the wafer 1 and the mark 8 is parallel or perpendicular to the grid-like dividing lines 2. This mark 8 may be a notch 8B shown in FIG. 12 or an orientation flat 8C shown in FIG. 13. Compared to marks such as the notch 8B and the orientation flat 8C, the minute flat mirror surface 8A is advantageous in that it allows for an increase in the number of semiconductor chips.

[0017] Next, a processing apparatus 10 according to one embodiment of the present invention will be described with reference to Figure 5. In Figure 5, reference numeral 30 denotes a base frame of a mark detection mechanism. For example, the frame of a device forming apparatus or the like is used as the base frame 30. An AC servo motor 31 with a built-in encoder is attached to the base frame 30, and a rotary table 33 is attached to the output shaft of the AC servo motor 31 via a table post 32. A porous portion 34 is disposed on the upper surface of the rotary table 33. Meanwhile, holes communicating with the porous portion 34 are formed inside the table post 32 and the rotary table 33, and a vacuum suction device (not shown) is connected to the holes, thereby attracting the wafer 1 to the porous portion 34.

[0018] A bracket 42 is attached to the base frame 30 via a sensor post 41, and an optical sensor 43 is attached to the bracket 42. The optical sensor 43 has a light-emitting section and a light-receiving section, and their optical axes L face the side surface of the wafer 1, and the height of the optical axis L coincides with the center of the wafer 1 in the thickness direction. The height of the optical axis L and the angle of the optical sensor 43 can be changed as long as it can receive reflected light.

[0019] The processing device 10 further includes a control unit 50 and a motor driver 60. Light emitted from the light-emitting unit of the optical sensor 43 is reflected by the side surface of the wafer 1, and when the wafer 1 rotates and the mark 8 comes directly in front of the optical sensor 43, the intensity of the reflected light received by the light-receiving unit reaches a maximum. The control unit 50 is composed of a computer having an arithmetic processing unit having a microprocessor such as a CPU (central processing unit), a storage device having memory such as a ROM (read only memory) or RAM (random access memory), and an input / output interface device.

[0020] The control unit 50 receives received light intensity information corresponding to the received light intensity from the optical sensor 43, as well as encoder value information from the encoder of the AC servo motor 31. The control unit 50 includes a rotation direction control unit 51 that controls the rotation direction of the AC servo motor 31, a rotation stop control unit 52 that stops the rotation of the AC servo motor 31, a storage unit 53 that stores the received light intensity information and the encoder value in association with each other, a mark center detection unit 54 that determines the center of the mark 8 as the area where the received light intensity of the reflected light is maximum, and a rotation speed control unit 55 that controls the rotation speed of the AC servo motor 31. Note that the control unit 50 is not limited to these, and may not include some of the functional units, or may include other functional units. For example, although not required in the detection method of the first embodiment described below, it is preferable that the control unit 50 further includes a threshold setting unit 56 and a threshold detection unit 57 in the second embodiment.

[0021] The rotation direction control unit 51 controls the rotation direction of the AC servo motor 31, thereby controlling the rotation direction of the wafer 1 held on the rotary table 33. In a method for detecting the mark 8, which will be described later, the rotation direction control unit 51 reverses the rotation direction of the wafer 1 at least once.

[0022] The rotation stop control unit 52 stops the rotation of the AC servo motor 31, thereby stopping the rotation of the wafer 1 held on the rotary table 33. In the method of detecting the mark 8, which will be described later, the rotation stop control unit 52 stops the rotation of the wafer 1 at least twice. The first stop is when the rotation direction control unit 51 reverses the direction of rotation, and the second stop is when the wafer 1 is positioned. The orientation of the positioned wafer 1 becomes constant, and the wafer 1 is transported to a subsequent process while maintaining that orientation.

[0023] The storage unit 53 stores the received light intensity information and the encoder value while the wafer 1 is rotating in association with each other.

[0024] The mark center detection unit 54 determines the position where the received light intensity is maximum as the center of the mark 8 based on the received light intensity information during rotation of the wafer 1. If there is only one position where the received light intensity is maximum, the mark center detection unit 54 can determine that position as the center of the mark 8. Furthermore, if there are multiple positions where the received light intensity is maximum, the mark center detection unit 54 can determine any of the initial, middle, or final positions as the center of the mark 8. Note that, when actually detecting during measurement, the position where the received light intensity is maximum can include both the position where the received light intensity is maximum and the position where the received light intensity starts to decrease from the position where the received light intensity is maximum. Therefore, if these positions are referred to as regions where the received light intensity is maximum, the mark center detection unit 54 determines the region where the received light intensity is maximum as the center of the mark 8.

[0025] The rotation speed control unit 55 controls the rotation speed of the AC servo motor 31 , thereby controlling the rotation speed of the wafer 1 held on the rotation table 33 .

[0026] The threshold setting unit 56 sets a threshold in advance for the received light intensity of the measurement light. This threshold is a threshold for changing the rotation speed. Setting of the threshold (threshold setting step) is performed before the detection process starts.

[0027] The threshold detection unit 57 detects whether the received light intensity of the measurement light exceeds the threshold set by the threshold setting unit 56 .

[0028] Next, a method for detecting the mark 8 according to the first embodiment will be described with reference to FIGS. 6 to 8. FIG. 6 is a flow chart of the detection method according to the first embodiment of the present invention, FIG. 7 is a diagram showing the measurement light and the position of the mark 8 in the detection steps (A) to (F), and FIG. 8 is a graph showing the received light intensity of the reflected light in the detection steps (A) to (F). The dashed line in FIG. 7 is a line connecting the center O of the wafer 1 and the circumferential center of the mark 8. In FIGS. 7 and 8, arrows represent the rotation direction and rotation speed. That is, in FIG. 7, the direction of the arrow represents the rotation direction, and the length of the arrow represents the rotation speed. In FIG. 8, the open arrow and the filled arrow represent different rotation directions, and the length of the open arrow and the filled arrow represents the rotation speed. The longer the length of the arrow, the faster the rotation speed.

[0029] 6, the detection method of the first embodiment includes a holding step S10, a first rotation step S11, a first rotation and stopping step S12, a second rotation step S13, a mark center detection step S14, and a second rotation and stopping step S15. In the detection method of this embodiment, the mark center detection step S14 is performed in the second rotation step S13.

[0030] The holding step S10 is a process of holding the wafer 1 on the turntable 33. In the holding step S10, the wafer 1 is placed on the turntable 33 so that its center O coincides with the rotation axis P of the turntable 33, and is adsorbed to the turntable 33.

[0031] In the first rotation step S11, the turntable 33 holding the wafer 1 is rotated in one direction (hereinafter referred to as the normal direction). At this time, the AC servo motor 31 rotates, and the orientation of the turntable 33 is input to the control unit 50 as an encoder value. Also, the optical sensor 43 projects light from the light-projecting unit onto the side surface of the wafer 1, and the intensity of the reflected light received by the light-receiving unit is input to the control unit 50 as received light intensity information.

[0032] At the position shown in Figure 7A, the mark 8 is misaligned with the optical axis L of the optical sensor 43, so the intensity of the received reflected light is extremely small, as shown in Figure 8A. As the wafer 1 continues to rotate in the forward direction from Figure 7A, the mark 8 overlaps with the optical axis L of the optical sensor 43, so the intensity of the received light gradually increases, as shown in Figure 8. Note that the forward rotation is indicated by a counterclockwise arrow in Figure 7, and by a hollow arrow in Figure 8.

[0033] At the position of FIG. 7B, the center of the mark 8 coincides with the optical axis L of the optical sensor 43, so that the received light intensity of the reflected light reaches a maximum value, as shown in FIG. 8B.

[0034] As the rotation of the wafer 1 in the forward direction progresses further from (B) in Fig. 7, the center of the mark 8 deviates from the optical axis L of the optical sensor 43, and the intensity of the received light gradually decreases as shown in (C) in Fig. 8. That is, at the position of (C) in Fig. 7, although the mark 8 overlaps with the optical axis L of the optical sensor 43, the center of the mark 8 deviates from the optical axis L of the optical sensor 43, and therefore the intensity of the received reflected light decreases from its maximum value as shown in (C) in Fig. 8.

[0035] In the first rotation stop step S12, after it is detected that the received light intensity of the reflected light has exceeded the maximum value and has begun to decrease, the rotation of the wafer 1 in the forward direction is stopped. Figure 7(D) shows the state in which the rotation of the wafer 1 has stopped in the first rotation stop step S12. At the position of Figure 7(D), the center of the mark 8 is misaligned with the optical axis L of the optical sensor 43, so the received light intensity of the reflected light has decreased from the maximum value, as shown in Figure 8(D).

[0036] In the second rotation step S13, the turntable 33 holding the wafer 1 is rotated in a direction opposite to the forward direction in which it was rotated in the first rotation step S11 (hereinafter referred to as the reverse direction). At this time, the AC servo motor 31 also rotates, and the orientation of the turntable 33 is input to the control unit 50 as an encoder value. In addition, the optical sensor 43 projects light from the light-projecting unit onto the side surface of the wafer 1, and the intensity of the reflected light received by the light-receiving unit is input to the control unit 50 as received light intensity information. Note that the rotation in the reverse direction is indicated by a clockwise arrow in FIG. 7, and by a solid black arrow in FIG. 8.

[0037] At the position shown in (E) of Figure 7, although the mark 8 overlaps with the optical axis L of the optical sensor 43, the center of the mark 8 is shifted from the optical axis L of the optical sensor 43, so that the received light intensity of the reflected light drops from its maximum value as shown in (E) of Figure 8, but the received light intensity increases as the rotation in the opposite direction progresses.

[0038] In the mark center detection step S14, the area where the received light intensity of the reflected light is at its maximum is determined to be the center of the mark 8. In the second rotation step S13, the received light intensity increases as the rotation of the wafer 1 in the inversion direction progresses, so the mark center detection unit 54 determines the area where the received light intensity is at its maximum as the center of the mark 8.

[0039] In the second rotation stopping step S15, the rotation of the wafer 1 is stopped instantly after the center of the mark 8 is detected in the mark center detecting step S14. Fig. 7F shows the state in which the rotation of the wafer 1 has stopped in the second rotation stopping step S15. At the position of Fig. 7F, the center of the mark 8 coincides with the optical axis L of the optical sensor 43, and therefore, as shown in Fig. 8F, the received light intensity of the reflected light reaches a maximum value.

[0040] In this way, after detecting that the received light intensity of the light reflected by the mark 8 indicating the crystal orientation has exceeded its maximum value and begun to decrease, the wafer 1 is rotated in the opposite direction and stopped with the center of the mark 8 aligned with the measurement light, thereby reducing the error between the measurement light at the stopping position and the center of the mark 8. This improves positioning accuracy compared to the conventional method of stopping rotation when the threshold is exceeded.

[0041] In this embodiment, as described above, the inversion position is detected in the first rotation step S11, and the area where the received light intensity of the reflected light is maximum is determined as the center of the mark 8 in the second rotation step S13.

[0042] Here, in order to improve the detection accuracy of the mark 8, it is preferable to set the rotation speed of the wafer 1 in the second rotation step S13 to be slower than the rotation speed of the wafer 1 in the first rotation step S11. That is, when rotating the wafer 1 in the second rotation step S13, the rotation speed control unit 55 sets the rotation speed to be slower than the rotation speed of the wafer 1 in the first rotation step S11. This improves the detection accuracy in the mark center detection step S14 of the second rotation step S13, thereby improving the positioning accuracy of the wafer 1, and also makes it possible to rotate the wafer 1 faster in the first rotation step S11, thereby shortening the time until the detection process is completed.

[0043] Next, a method for detecting the mark 8 according to the second embodiment will be described with reference to FIGS. 9 to 11. FIG. 9 is a flow chart of the detection method according to the second embodiment of the present invention, FIG. 10 is a diagram showing the measurement light and the position of the mark 8 in the detection steps (A) to (F), and FIG. 11 is a graph showing the received light intensity of the reflected light in the detection steps (A) to (F). The dashed line in FIG. 10 is a line connecting the center O of the wafer 1 and the circumferential center of the mark 8. In FIGS. 10 and 11, arrows represent the rotation direction and rotation speed. That is, in FIG. 10, the direction of the arrow represents the rotation direction, and the length of the arrow represents the rotation speed. In FIG. 11, the open arrow and the filled arrow represent different rotation directions, and the length of the open arrow and the filled arrow represents the rotation speed. The longer the length of the arrow, the faster the rotation speed.

[0044] 9, the detection method of the second embodiment includes a holding step S10, a first rotation step S11, a threshold detection step S16, a mark center detection step S14, a first rotation stopping step S12, a second rotation step S13, and a second rotation stopping step S15. In the detection method of this embodiment, the mark center detection step S14 is performed in the first rotation step S11.

[0045] The holding step S10 is a process of holding the wafer 1 on the turntable 33. In the holding step S10, the wafer 1 is placed on the turntable 33 so that its center O coincides with the rotation axis P of the turntable 33, and is adsorbed to the turntable 33.

[0046] In the first rotation step S11, the turntable 33 holding the wafer 1 is rotated in one direction (hereinafter referred to as the normal direction). At this time, the AC servo motor 31 rotates, and the orientation of the turntable 33 is input to the control unit 50 as an encoder value. Also, the optical sensor 43 projects light from the light-projecting unit onto the side surface of the wafer 1, and the intensity of the reflected light received by the light-receiving unit is input to the control unit 50 as received light intensity information.

[0047] At the position shown in Figure 10(A), the mark 8 is misaligned with the optical axis L of the optical sensor 43, and therefore the received light intensity of the reflected light is extremely small, as shown in Figure 11(A). As the wafer 1 continues to rotate in the forward direction from Figure 10(A), the mark 8 overlaps with the optical axis L of the optical sensor 43, and the received light intensity gradually increases, as shown in Figure 11. Note that forward rotation is indicated by a counterclockwise arrow in Figure 10, and by a hollow arrow in Figure 11.

[0048] In threshold detection step S16, it is detected that the received light intensity of the reflected light exceeds a preset threshold. When threshold detection unit 57 detects that the received light intensity of the measurement light exceeds threshold T, rotation speed control unit 55 slows the rotation speed below the rotation speed before exceeding threshold T.

[0049] At the position of FIG. 10B, the center of the mark 8 coincides with the optical axis L of the optical sensor 43, so that the received light intensity of the reflected light reaches a maximum value, as shown in FIG.

[0050] In the mark center detection step S14, the area where the received light intensity of the reflected light is at its maximum is determined to be the center of the mark 8. In the first rotation step S11, the received light intensity increases as the rotation of the wafer 1 in the forward direction progresses, so the mark center detection unit 54 determines the area where the received light intensity is at its maximum as the center of the mark 8.

[0051] As the rotation of the wafer 1 in the forward direction progresses further from (B) in Figure 10, the center of the mark 8 deviates from the optical axis L of the optical sensor 43, and the intensity of the received light gradually decreases as shown in (C) in Figure 10. That is, at the position of (C) in Figure 10, although the mark 8 overlaps with the optical axis L of the optical sensor 43, the center of the mark 8 deviates from the optical axis L of the optical sensor 43, and therefore the intensity of the received reflected light decreases from its maximum value as shown in (C) in Figure 11.

[0052] In the first rotation stop step S12, after it is detected that the received light intensity of the reflected light has exceeded the maximum value and has begun to decrease, the rotation of the wafer 1 in the forward direction is stopped. Figure 10(D) shows the state in which the rotation of the wafer 1 has stopped in the first rotation stop step S12. At the position of Figure 10(D), the center of the mark 8 is misaligned with the optical axis L of the optical sensor 43, so the received light intensity of the reflected light has decreased from the maximum value, as shown in Figure 11(D).

[0053] In the second rotation step S13, the turntable 33 holding the wafer 1 is rotated in a reverse direction, which is the opposite direction to the forward direction in which it was rotated in the first rotation step S11. At this time, the AC servo motor 31 also rotates, and the orientation of the turntable 33 is input to the control unit 50 as an encoder value. In addition, the optical sensor 43 projects light from the light-projecting unit onto the side surface of the wafer 1, and the intensity of the reflected light received by the light-receiving unit is input to the control unit 50 as received light intensity information. Note that the rotation in the reverse direction is indicated by a clockwise arrow in FIG. 10 and by a solid black arrow in FIG. 11.

[0054] 10(E), although the mark 8 overlaps with the optical axis L of the optical sensor 43, the center of the mark 8 is misaligned with the optical axis L of the optical sensor 43, so that the received light intensity of the reflected light drops from its maximum value as shown in FIG. 11(E). However, as rotation in the opposite direction progresses, the received light intensity increases. The rotation speed in the second rotation step S13 does not need to be the same as the rotation speed after exceeding the threshold value T, but may be a relatively fast rotation speed, for example, a rotation speed approximately the same as the rotation speed before exceeding the threshold value T in the first rotation step S11. Note that the rotation speed in the second rotation step S13 may be the same as the rotation speed after exceeding the threshold value T.

[0055] In the second rotation stopping step S15, the rotation of the wafer 1 is stopped instantaneously at the position where the center of the mark 8 is detected in the mark center detecting step S14 performed in the first rotation step S11. Fig. 10(F) shows the state where the rotation of the wafer 1 has stopped in the second rotation stopping step S15. At the position of Fig. 10(F), the center of the mark 8 coincides with the optical axis L of the optical sensor 43, and therefore, as shown in Fig. 11(F), the received light intensity of the reflected light reaches a maximum value.

[0056] In this way, after detecting that the received light intensity of the light reflected by the mark 8 indicating the crystal orientation has exceeded its maximum value and begun to decrease, the wafer 1 is rotated in the opposite direction and stopped with the center of the mark 8 aligned with the measurement light, thereby reducing the error between the measurement light at the stopping position and the center of the mark 8. This improves positioning accuracy compared to the conventional method of stopping rotation when the threshold is exceeded.

[0057] Furthermore, in this embodiment, as described above, the area where the received light intensity of the reflected light is at its maximum value is determined as the center of mark 8 in the first rotation step S11, and then the mark 8 is returned to the position determined as the center of mark 8 in the second rotation step S13.

[0058] Here, in order to improve the detection accuracy of the mark 8, a threshold value T is detected in the threshold value detection step S16, and the rotation speed after it is detected that the threshold value T has been exceeded is set to be slower than the rotation speed before the threshold value T was exceeded. This improves the detection accuracy in the mark center detection step S14 of the second rotation step S13, and improves the positioning accuracy of the wafer 1. Conversely, because the wafer 1 can be rotated at a relatively high speed before the threshold value T is exceeded in the first rotation step S11 and in the second rotation step S13, the time until the detection process is completed can be shortened. Furthermore, this threshold value T is a threshold value for changing the rotation speed, unlike a conventional threshold value for detecting the mark 8, and does not require precise setting.

[0059] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0060] For example, the above-described embodiment exemplifies a processing device 10 in which the optical axis L of the light-emitting and light-receiving parts of the optical sensor 43 faces the side of the wafer 1, and the height of the optical axis L coincides with the center of the wafer 1 in the thickness direction, but this is not limited to this.

[0061] 14, in the processing apparatus 10 of the modified example, a pair of brackets 42 are attached to the base frame 30 via sensor posts 41, and an optical sensor 43 is attached to the pair of brackets 42. The optical sensor 43 includes a light-emitting unit attached to the upper bracket 42 and a light-receiving unit attached to the lower bracket 42, and their optical axes L are oriented in a direction perpendicular to the surface direction of the wafer 1 (the parallel front and back surfaces). Light emitted from the light-emitting unit of the optical sensor 43 is blocked by the wafer 1, and when the wafer 1 rotates and the mark 8 is directly below the optical sensor 43, the intensity of the transmitted light that passes through the wafer 1 and is received by the light-receiving unit reaches a maximum. Note that other configurations are similar to those of the processing apparatus 10 of the above-described embodiment, and therefore the same reference numerals are used in the drawings and their description will be omitted.

[0062] This specification describes at least the following items. Note that the components in parentheses correspond to those in the above-described embodiment, but are not limited to these.

[0063] (1) A detection method for detecting a mark (mark 8) indicating a crystal orientation formed on the outer periphery of a semiconductor wafer (semiconductor wafer 1), comprising: a first rotation step (first rotation step S11) of relatively rotating the measurement light and the semiconductor wafer around a rotation axis (rotation axis P) passing through the center of the semiconductor wafer while irradiating the outer circumferential edge of the semiconductor wafer with measurement light, receiving the measurement light transmitted through or reflected by the mark, and detecting when the received light intensity of the measurement light exceeds a maximum value and starts to decrease; a second rotation step (second rotation step S13) in which, after the first rotation step, the measurement light and the semiconductor wafer are relatively rotated in a direction opposite to the direction of rotation in the first rotation step, and the measurement light transmitted through or reflected by the mark is received; a mark center detection step (mark center detection step S14) of determining a region where the received light intensity of the measurement light is maximum in the first rotation step or the second rotation step as the center of the mark; and a rotation stopping step (second rotation stopping step S15) of stopping the relative rotation between the semiconductor wafer and the measurement light at the center of the mark after the second rotation step. Detection method.

[0064] According to (1), after detecting that the received light intensity of the measurement light transmitted through or reflected by the mark indicating the crystal orientation exceeds its maximum value and starts to decrease, the semiconductor wafer is stopped with the center of the mark aligned with the measurement light by rotating the semiconductor wafer relatively in the opposite direction, thereby reducing the error between the measurement light and the center of the mark at the stopping position. This improves positioning accuracy compared to the conventional method of stopping the relative rotation when the threshold is exceeded.

[0065] Furthermore, when setting a threshold as in the conventional method, it is important to set the threshold in order to reduce the error between the measurement light at the stop position and the center of the mark. However, according to (1), there is no need to set a threshold, and positioning accuracy can be improved.

[0066] (2) The detection method according to (1), In the second rotation step, a region where the received light intensity of the measurement light is maximum is determined as the center of the mark, and the measurement light and the semiconductor wafer are rotated relatively until the center of the mark is determined. Detection method.

[0067] According to (2), the positioning accuracy can be improved by detecting the inversion position in the first rotation step, determining the area where the received light intensity of the measurement light is maximum as the center of the mark in the second rotation step, and stopping the rotation at the center of the mark.

[0068] (3) The detection method according to (2), The rotation speed in the second rotation step is set to be slower than the rotation speed in the first rotation step. Detection method.

[0069] According to (3), in the second rotation step, in which the mark center detection step for determining the mark center is performed, the rotation speed is slowed down to improve the detection accuracy of the mark center and the wafer positioning accuracy. Also, in the first rotation step, the relative rotation is performed at a relatively high speed, which shortens the detection processing time.

[0070] (4) The detection method according to (1), In the first rotation step, a region where the received light intensity of the measurement light is maximum is determined as the center of the mark; In the second rotating step, the measurement light and the semiconductor wafer are rotated relative to each other until the measurement light is positioned at the center of the mark. Detection method.

[0071] According to (4), the center of the mark can be detected more accurately by determining the area where the received light intensity of the measurement light is at its maximum in the first rotation step, and then returning the area where the received light intensity of the measurement light is at its maximum in the second rotation step and stopping the rotation.

[0072] (5) The detection method according to (4), a threshold setting step of setting a threshold for the received light intensity of the measurement light; and a threshold detection step (threshold detection step S16) of detecting whether the received light intensity of the measurement light exceeds the threshold, In the first rotation step, when the received light intensity of the measurement light exceeds the threshold, the rotation speed is slowed down compared to the rotation speed before the received light intensity of the measurement light exceeded the threshold. Detection method.

[0073] According to (5), the detection processing time can be shortened by rotating the object at a relatively high speed until the threshold is exceeded in the first rotation step. After the threshold is exceeded, the rotation speed can be slowed down to improve the detection accuracy.

[0074] (6) The detection method according to any one of (1) to (5), The mark is a flat mirror surface portion (micro flat mirror surface portion 8A) formed at a position overlapping with the chamfered portion on the outer periphery of the semiconductor wafer when viewed from the rotation axis direction, In the first rotation step and the second rotation step, measurement light that is irradiated from the side of the semiconductor wafer and reflected by the flat mirror surface portion is received. Detection method.

[0075] According to (6), the mark indicating the crystal orientation is configured as a flat mirror surface formed at a position overlapping with the chamfered portion on the outer periphery of the semiconductor wafer, thereby maximizing the device area of ​​the semiconductor wafer and thereby increasing the number of devices produced per wafer. Furthermore, since the mark is a flat mirror surface perpendicular to the surface direction of the semiconductor wafer and accurately reflects light incident from the side, a non-contact optical reflection method that does not risk damaging the semiconductor wafer can be suitably adopted as a mark detection method.

[0076] (7) A processing device (processing device 10) for detecting a mark (mark 8) indicating a crystal orientation formed on the outer periphery of a semiconductor wafer (semiconductor wafer 1), a holding table (rotary table 33) for holding the semiconductor wafer; a crystal orientation detection sensor (optical sensor 43) having a light projecting unit that projects measurement light onto the mark on the semiconductor wafer and a light receiving unit that receives measurement light reflected by or transmitted through the mark; a rotation drive unit (AC servo motor 31) that rotates the holding table and the crystal orientation detection sensor relative to each other around a rotation axis (rotation axis P) that passes through the center of the holding table; a control unit (control unit 50), The control unit a rotation direction control unit (rotation direction control unit 51) that controls the direction of the relative rotation; a rotation stop control unit (rotation stop control unit 52) ​​that stops the relative rotation; a mark center detection unit (mark center detection unit 54) that determines the area where the received light intensity of the measurement light is maximum as the center of the mark, the rotation direction control unit changes the rotation direction of the relative rotation after detecting that the received light intensity of the measurement light exceeds a maximum value and starts to decrease while rotating the relative rotation in a predetermined direction; The rotation stop control unit stops the relative rotation at the center of the mark after changing the rotation direction of the relative rotation.

[0077] According to (7), the semiconductor wafer is stopped with the center of the mark indicating the crystal surrounding formed on the semiconductor wafer aligned with the measurement light, thereby improving the positioning accuracy, which simplifies or eliminates the alignment process for positioning in the subsequent process.

[0078] (8) The processing device according to (7), The control unit further includes a rotation speed control unit (rotation speed control unit 55) that controls the rotation speed of the relative rotation. Processing equipment.

[0079] According to (8), by varying the rotation speed of the relative rotation, it is possible to improve the detection accuracy while shortening the detection processing time.

[0080] (9) The processing device according to (8), the mark center detection unit detects the center of the mark while rotating the mark relative to the target object in a direction opposite to the predetermined direction; the rotation speed control unit makes the rotation speed when the relative rotation is caused in the opposite direction slower than the rotation speed when the relative rotation is caused in the predetermined direction. Processing equipment.

[0081] According to (9), the accuracy of detecting the mark center can be improved by slowing down the rotation speed in the opposite direction that determines the mark center, and the accuracy of wafer positioning can be improved. In addition, by rotating the wafer in the previous direction at a relatively high speed, the detection process time can be shortened.

[0082] (10) The processing device according to (8), The control unit a threshold setting unit (threshold setting unit 56) that sets a threshold for the received light intensity of the measurement light; a threshold detection unit (threshold detection unit 57) that detects whether the received light intensity of the measurement light exceeds the threshold, the mark center detection unit detects the center of the mark while causing the relative rotation in the predetermined direction; the rotation speed control unit, when the threshold detection unit detects that the received light intensity of the measurement light exceeds the threshold, reduces the rotation speed below the rotation speed before the threshold is exceeded. Processing equipment.

[0083] According to (10), the center of the mark can be determined as the area where the intensity of the measurement light is at its maximum when rotated in a predetermined direction, and then the rotation can be stopped by returning the area where the intensity of the measurement light is at its maximum when rotated in the reverse direction. This makes it possible to detect the center of the mark more accurately. [Explanation of symbols]

[0084] 1. Semiconductor wafer 8 marks 8A Micro flat mirror surface part (flat mirror surface part) 10 Processing equipment 31 AC servo motor (rotation drive unit) 33 Rotary table (holding table) 43 Optical sensor (crystal orientation detection sensor) 50 control section 51 Rotation direction control unit 52 Rotation stop control section 54 Mark center detection unit 55 Rotational speed control section 56 Threshold setting unit 57 Threshold detection unit S11 1st rotation step S13 2nd rotation step S14 Mark center detection step S15 Second rotation stop step (rotation stop step) S16 Threshold detection step P rotation axis

Claims

1. A detection method for detecting a mark indicating a crystal orientation formed on an outer peripheral edge of a semiconductor wafer, comprising: a first rotation step of relatively rotating the measurement light and the semiconductor wafer around a rotation axis passing through the center of the semiconductor wafer while irradiating the outer peripheral edge of the semiconductor wafer with measurement light, and receiving the measurement light transmitted through or reflected by the mark, and detecting when the received light intensity of the measurement light exceeds a maximum value and starts to decrease; a second rotation step in which, after the first rotation step, the measurement light and the semiconductor wafer are relatively rotated in a direction opposite to the direction of rotation in the first rotation step, and the measurement light transmitted through or reflected by the mark is received; a mark center detection step of determining a region where the received light intensity of the measurement light is maximum as the center of the mark in the first rotation step or the second rotation step; a rotation stopping step of stopping the relative rotation between the semiconductor wafer and the measurement light at the center of the mark after the second rotation step. Detection method.

2. 2. The detection method according to claim 1, In the second rotating step, a region where the received light intensity of the measurement light is maximum is determined as the center of the mark, and the measurement light and the semiconductor wafer are rotated relative to each other until the center of the mark is determined. Detection method.

3. 3. The detection method according to claim 2, The rotation speed in the second rotation step is set to be slower than the rotation speed in the first rotation step. Detection method.

4. 2. The detection method according to claim 1, In the first rotation step, a region where the received light intensity of the measurement light is maximum is determined as the center of the mark; In the second rotating step, the measurement light and the semiconductor wafer are rotated relative to each other until the measurement light is positioned at the center of the mark. Detection method.

5. 5. The detection method according to claim 4, a threshold setting step of setting a threshold for the received light intensity of the measurement light; a threshold detection step of detecting whether the received light intensity of the measurement light exceeds the threshold, In the first rotation step, when the received light intensity of the measurement light exceeds the threshold, the rotation speed is slowed down compared to the rotation speed before the received light intensity of the measurement light exceeded the threshold. Detection method.

6. The detection method according to any one of claims 1 to 5, the mark is a flat mirror surface portion formed at a position overlapping with a chamfered portion on the outer periphery of the semiconductor wafer when viewed from the rotation axis direction, In the first rotation step and the second rotation step, measurement light that is irradiated from a side of the semiconductor wafer and reflected by the flat mirror surface portion is received. Detection method.

7. A processing device for detecting a mark indicating a crystal orientation formed on an outer peripheral edge of a semiconductor wafer, a holding table for holding the semiconductor wafer; a crystal orientation detection sensor having a light projecting unit that projects measurement light onto the mark on the semiconductor wafer and a light receiving unit that receives measurement light reflected by or transmitted through the mark; a rotation drive unit that rotates the holding table and the crystal orientation detection sensor relative to each other around a rotation axis that passes through the center of the holding table; a control unit, The control unit a rotation direction control unit that controls the direction of the relative rotation; a rotation stop control unit that stops the relative rotation; a mark center detection unit that determines a region where the received light intensity of the measurement light is maximum as the center of the mark, the rotation direction control unit changes the rotation direction of the relative rotation after detecting that the received light intensity of the measurement light exceeds a maximum value and starts to decrease while rotating the relative rotation in a predetermined direction; The rotation stop control unit stops the relative rotation at the center of the mark after changing the rotation direction of the relative rotation.

8. 8. The processing device according to claim 7, The control unit further includes a rotation speed control unit that controls the rotation speed of the relative rotation. Processing equipment.

9. 9. The processing device according to claim 8, the mark center detection unit detects the center of the mark while rotating the mark relative to the target object in a direction opposite to the predetermined direction; the rotation speed control unit makes the rotation speed when the relative rotation is caused in the opposite direction slower than the rotation speed when the relative rotation is caused in the predetermined direction. Processing equipment.

10. 9. The processing device according to claim 8, The control unit a threshold setting unit that sets a threshold for the received light intensity of the measurement light; a threshold detection unit that detects whether the received light intensity of the measurement light exceeds the threshold, the mark center detection unit detects the center of the mark while causing the relative rotation in the predetermined direction; the rotation speed control unit, when the threshold detection unit detects that the received light intensity of the measurement light exceeds the threshold, reduces the rotation speed below the rotation speed before the threshold was exceeded. Processing equipment.

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