Wafer alignment measuring device, wafer alignment measuring method, bonding device and semiconductor structure

Abstract

The embodiment of the invention provides a wafer alignment measuring device, a wafer alignment measuring method, a bonding device and a semiconductor structure. The wafer alignment measuring device comprises a light source assembly, a light splitting part, a polarization part and an imaging assembly, the light source assembly is used for providing original light propagating in the second direction. The beam splitter is used for reflecting original light based on the polarization direction; wherein the reflected light is a first light with a first polarization direction; the first light is propagated to a first alignment mark located on the first wafer through the polarization piece in the first direction, and is propagated to a second alignment mark located on the second wafer through the first wafer; the second light reflected by the first alignment mark and the second alignment mark has a second polarization direction after passing through the polarization piece; the second light with the second polarization direction is transmitted to the imaging assembly along the third direction through the light splitting part; the imaging assembly is used for collecting first moire fringes formed by the second light; the first moire fringe is used for determining whether the first alignment mark and the second alignment mark are aligned.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of integrated circuit technology, and in particular, to a wafer alignment measurement device, a measurement method, a bonding device, and a semiconductor structure. Background Art

[0002] In the field of chip packaging, in order to further reduce the chip area and improve the integration density, the bonding technology is usually used to realize the bonding connection between wafers during the manufacturing process. To ensure the bonding quality, reduce the influence of the bonding process on the electrical signal transmission between chips, and ensure the reliability of the electrical signal transmission, the alignment deviation of the bonding must be strictly controlled within a small size range.

[0003] Precisely measuring the position deviation between wafers, thereby improving the bonding accuracy, is beneficial to further realizing high-density and high-performance chip stacking. Summary of the Invention

[0004] In view of this, embodiments of the present application provide a wafer alignment measurement device, a measurement method, a bonding device, and a semiconductor structure.

[0005] To achieve the above object, the technical solution of the embodiments of the present application is realized as follows: Embodiments of the present application provide a wafer alignment measurement device, including: a light source component, a beam splitter, a polarizer, and an imaging component; wherein, the imaging component, the beam splitter, and the polarizer are arranged in sequence along a first direction; the light source component and the beam splitter are arranged along a second direction; wherein, the first direction and the second direction have a first included angle; The light source component is used to provide an original light ray propagating along the second direction; The beam splitter is used to reflect the original light ray based on the polarization direction; wherein, the reflected light ray is a first light ray having a first polarization direction; The first light ray propagates along the first direction through the polarizer to a first alignment mark on a first wafer, and transmits through the first wafer to a second alignment mark on a second wafer; The second light ray reflected by the first alignment mark and the second alignment mark has a second polarization direction after passing through the polarizer; the second polarization direction is different from the first polarization direction; The second light ray having the second polarization direction transmits through the beam splitter along a third direction to the imaging component; wherein, the third direction is opposite to the first direction; the imaging component is used to collect a first Moiré fringe formed by the second light ray; the first Moiré fringe is used to determine whether the first alignment mark and the second alignment mark are aligned.

[0006] In some embodiments, the alignment measurement device further includes: A data processing device is connected to the imaging component. The data processing device is configured to determine whether the first alignment mark and the second alignment mark are aligned based on the first Moiré fringe and a preset second Moiré fringe.

[0007] In some embodiments, the imaging component includes a tube lens and an image sensor; The tube lens is located between the beam splitter and the image sensor and is configured to converge the second light beam that has passed through the beam splitter. The image sensor is configured to collect the first Moiré fringe formed by the second light beam.

[0008] In some embodiments, the alignment measurement device further includes: An objective lens assembly is located between the polarizer and the first wafer. The objective lens assembly is configured to focus light to a preset position between the first alignment mark and the second alignment mark.

[0009] In some embodiments, the light source assembly includes a laser emitter; The laser emitter is configured to emit the original light beam with a wavelength greater than the wavelength of visible light.

[0010] In some embodiments, the first alignment mark includes a plurality of first grating stripes arranged along a fourth direction, or the first alignment mark includes a plurality of first grating annular stripes arranged in concentric circles; the fourth direction is parallel to the surface of the first wafer; And / or, the second alignment mark includes a plurality of second grating stripes arranged along a fifth direction, or the second alignment mark includes a plurality of second grating annular stripes arranged in concentric circles; the fifth direction is parallel to the surface of the second wafer.

[0011] In some embodiments, along the fourth direction, the first grating stripes are arranged according to a first period; Along the fifth direction, the second grating stripes are arranged according to a second period; The absolute value of the difference between the first period and the second period is greater than 0 and less than or equal to a preset first threshold.

[0012] In some embodiments, along the first direction, there is a first distance between the first alignment mark and the second alignment mark; The difference between the width of the first grating stripe and the first distance is less than a preset second threshold; the difference between the width of the first grating annular stripe and the first distance is less than a preset third threshold; And / or The difference between the width of the second grating stripe and the first distance is less than the second threshold; the difference between the width of the first grating ring and the first distance is less than the third threshold.

[0013] In some embodiments, the material of the first grating stripe and / or the material of the second grating stripe includes a metallic material.

[0014] An embodiment of the present application provides a bonding device, including the alignment measurement device and the control component described in any one of the above, The control component is configured to move the first wafer and / or the second wafer to be bonded according to the measurement information of the alignment measurement device, so that the first alignment mark and the second alignment mark are aligned.

[0015] An embodiment of the present application provides a semiconductor structure, including a first wafer; The first wafer includes a first alignment mark; the first alignment mark includes a plurality of first grating stripes arranged along a fourth direction, or the first alignment mark includes a plurality of first grating rings arranged in concentric circles; The first alignment mark is configured to jointly reflect light with a second alignment mark located on a second wafer to form a first Moiré fringe; the first Moiré fringe is used to determine whether the first alignment mark and the second alignment mark are aligned.

[0016] In some embodiments, the first wafer further includes a first silicon substrate and at least one first transmissive layer; The first alignment mark is located on a side of the first transmissive layer close to the first silicon substrate; or the first alignment mark is located on a side of the first transmissive layer away from the first silicon substrate; The transmittance of the first transmissive layer to light is greater than or equal to a preset first transmittance; The transmittance of the first silicon substrate to light is greater than or equal to a preset second transmittance.

[0017] In some embodiments, the first transmittance is greater than or equal to 85%; and / or, the second transmittance is greater than or equal to 50%.

[0018] In some embodiments, the semiconductor structure further includes the second wafer; The first wafer is bonded to the second wafer; The second alignment mark includes a plurality of second grating stripes arranged along a fifth direction, or the second alignment mark includes a plurality of second grating rings arranged in concentric circles.

[0019] In some embodiments, the second wafer further includes a second silicon substrate and at least one second transmissive layer; the second alignment mark is located on a side of the second transmissive layer close to the second silicon substrate, or the second alignment mark is located on a side of the second transmissive layer away from the second silicon substrate; The light transmittance of the second transmissive layer is greater than or equal to the first transmittance; The light transmittance of the second silicon substrate is greater than or equal to the second transmittance.

[0020] In some embodiments, the first transmissive layer includes a silicon dioxide material and / or a silicon nitride material.

[0021] In some embodiments, the first wafer includes a plurality of first chip regions and a dicing street region located between the first chip regions; the first alignment mark is located within the dicing street region.

[0022] An embodiment of the present application provides a wafer alignment measurement method, including: Using a light source assembly to provide original light propagating in a second direction; After being reflected by a beam splitter, the original light propagates along a first direction through a polarizer to a first alignment mark on a first wafer, and then propagates through the first wafer to a second alignment mark on a second wafer; Wherein, the light reflected by the beam splitter is a first light having a first polarization direction; the light reflected by the first alignment mark and the second alignment mark is a second light, and the second light has a second polarization direction after passing through the polarizer; the second polarization direction is different from the first polarization direction; Using an imaging assembly to collect a first Moiré fringe formed by the second light having the second polarization direction after passing through the beam splitter; the first Moiré fringe is used to determine whether the first alignment mark and the second alignment mark are aligned; Wherein, the imaging assembly, the beam splitter, and the polarizer are arranged in sequence along the first direction, and the light source assembly and the beam splitter are arranged along the second direction; the first direction and the second direction have a first included angle.

[0023] In some embodiments, the alignment measurement method further includes: Determining a translation offset between the first alignment mark and the second alignment mark according to the first Moiré fringe and a preset second Moiré fringe; Horizontally moving the first wafer and / or the second wafer according to the translation offset so that the first alignment mark is aligned with the second alignment mark.

[0024] In some embodiments, the alignment measurement method further includes: Determine the offset angle between the first alignment mark and the second alignment mark according to the normal vectors of the first alignment mark and the second alignment mark; Adjust the horizontal rotation angle of the first wafer and / or the second wafer according to the offset angle, so that the first alignment mark and the second alignment mark are parallel to the same plane.

[0025] The wafer alignment measurement device provided by the embodiments of the present application, on the one hand, uses light with better penetrability relative to the first wafer or the second wafer, so that it can propagate through the first wafer to the second alignment mark on the second wafer, and it is possible to directly observe or measure whether the first alignment mark and the second alignment mark are aligned, which simplifies the alignment recognition steps and can reduce the measurement error caused by separate observations. On the second hand, by using the first light and the second light with different polarization directions, the transmission and reflection selection of the incident light and the reflected light of the alignment mark (the first alignment mark or the second alignment mark) can be realized, and the imaging component collects all the reflected second light, which can increase the imaging quality of the first Moiré fringe and is beneficial to improving the extraction of alignment information. On the third hand, by using the first Moiré fringe, the deviation between the alignment marks can be amplified, which is beneficial to improving the accuracy of alignment measurement. Description of the Drawings

[0026] Figure 1 is the wafer alignment measurement device provided by the embodiments of the present application Figure 1 ; Figure 2 is the wafer alignment measurement device provided by the embodiments of the present application Figure 2 ; Figure 3 is the wafer alignment measurement device provided by the embodiments of the present application Figure 3 ; Figure 4 is the wafer alignment measurement device provided by the embodiments of the present application Figure 4 ; Figure 5A is the schematic diagram of the first alignment mark provided by the embodiments of the present application Figure 1 ; Figure 5B is the schematic diagram of the first alignment mark provided by the embodiments of the present application Figure 2 ; Figure 6 is the schematic diagram of the first alignment mark provided by the embodiments of the present application Figure 3 ; Figure 7 is the comparison diagram of the first alignment mark and the second alignment mark in the embodiments of the present application; Figure 8 is the schematic diagram of the first Moiré fringe provided by the embodiments of the present application; Figure 9Schematic diagram of the wafer position provided by the embodiment of the present application; Figure 10 Figure 5 of the wafer alignment measurement device provided by the embodiment of the present application; Figure 11 Schematic diagram of the signal curve provided by the embodiment of the present application; Figure 12 Schematic diagram of the steps of the wafer alignment measurement method provided by the embodiment of the present application; Figure 13 Schematic diagram of the bonding device structure provided by the embodiment of the present application; Figure 14 Schematic diagram of the structure of the semiconductor structure provided by the embodiment of the present application Figure 1 ; Figure 15A Schematic diagram of the structure of the semiconductor structure provided by the embodiment of the present application Figure 2 ; Figure 15B Schematic diagram of the structure of the semiconductor structure provided by the embodiment of the present application Figure 3 ; Figure 16A Schematic diagram of the structure of the semiconductor structure provided by the embodiment of the present application Figure 4 ; Figure 16B Figure 5 of the schematic diagram of the structure of the semiconductor structure provided by the embodiment of the present application. Detailed implementation manners

[0027] Next, in combination with the embodiments of the present application and the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0028] In the following description, a large number of specific details are given to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known to the art are not described; that is, not all features of the actual embodiments are described here, and the well-known functions and structures are not described in detail.

[0029] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present application. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, identify the presence of the specified features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the related listed items.

[0030] To thoroughly understand the present application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solutions of the present application. The preferred embodiments of the present application are described in detail below. However, in addition to these detailed descriptions, the present application may have other embodiments.

[0031] In the bonding alignment technology, generally, a high-precision optical microscope or imaging device is used to take pictures of specific alignment mark patterns pre-designed on the wafer surface respectively, and then the alignment deviation is calculated based on the center positions of the two alignment mark patterns.

[0032] However, this alignment method is limited by the resolution of the optical system and the recognition accuracy of the image processing algorithm. To further improve the diffraction resolution limit of the optical system, it is necessary to further reduce the light source wavelength to reduce the diffraction limit and improve the resolution of the optical system. However, the shorter the light source wavelength, the higher its energy, which is easily absorbed or scattered by substances, and it is also difficult to obtain sufficient effective optical signals and high-quality images.

[0033] In view of this, an embodiment of the present application provides a wafer alignment measurement device, as Figure 1 shown, the wafer alignment measurement device 100 includes: a light source assembly 101, a beam splitter 102, a polarizer 103 and an imaging assembly 104; wherein, the imaging assembly 104, the beam splitter 102 and the polarizer 103 are arranged in sequence along a first direction (negative Z-axis direction); the light source assembly 101 and the beam splitter 102 are arranged along a second direction; wherein, the first direction and the second direction have a first included angle; The light source assembly 101 is used to provide an original light ray L0 propagating along the second direction; The beam splitter 102 is used to reflect the original light ray L0 based on the polarization direction; wherein, the reflected light ray is a first light ray L1 having a first polarization direction; The first light ray L1 propagates along the first direction through the polarizer 103 to the first alignment mark 106 on the first wafer 105, and passes through the first wafer 105 to the second alignment mark 108 on the second wafer 107; The second light ray reflected by the first alignment mark 106 and the second alignment mark 108 has a second polarization direction after passing through the polarizer 103; the second polarization direction is different from the first polarization direction; The second light ray L2 with the second polarization direction transmits through the beam splitter 102 along the third direction (the positive direction of the Z axis) and propagates to the imaging component 104; wherein, the third direction is opposite to the first direction; the imaging component 104 is used to collect the first Moiré fringe formed by the second light ray L2; the first Moiré fringe is used to determine whether the first alignment mark and the second alignment mark are aligned.

[0034] That is to say, the propagation path of the light ray is successively the light source component 101 - the beam splitter 102 - the polarizer 103 - the first alignment mark 106 / the second alignment mark 108 - the polarizer 103 - the beam splitter 102 - the imaging component 104.

[0035] Among them, the beam splitter 102 can separate the light ray into polarized lights with different polarization directions, reflect the light rays with some polarization directions, and transmit the light rays with other polarization directions, thereby realizing the separation of the light rays. The original light ray L0 can be natural light (or other light rays without a specific polarization direction), or can be light rays with one or several polarization directions. Exemplarily, the original light ray L0 is natural light, and after passing through the beam splitter 102, it can be divided into two beams of light, namely a transmitted light and a reflected light. Among them, the reflected light is the first light ray L1 with the first polarization direction. The original light ray L0 can also be a light ray containing the first polarization direction, such as a light ray only containing the first polarization direction or a light ray also containing one or more polarization directions. If the original light ray L0 does not contain polarized light that can transmit through the beam splitter 102, then there is no transmitted light after the original light ray passes through the beam splitter 102, and only the reflected first light ray L1 is included.

[0036] The polarizer 103 can change the polarization direction or polarization state of the light ray, that is, the polarization direction or polarization state of the light ray passing through the polarizer 103 is different from that of the light ray before passing through the polarizer 103. In this way, the reflected second light ray can have a second polarization direction after passing through the polarizer 103, and the second polarization direction is different from the first polarization direction, can transmit through the beam splitter 102, and propagate along the third direction to the imaging component 104. It can be understood that the first light ray L1 changes its polarization direction or polarization state once after passing through the polarizer 103, and the reflected second light ray changes its polarization direction or polarization state once again after passing through the polarizer 103. The specific form of change of the polarizer 103 during these two light transmissions is not limited here, only the second light ray has a second polarization direction that can transmit through the beam splitter 102 after passing through the polarizer 103. In this way, the first light ray L1 can be reflected by the beam splitter 102, while the second light ray L2 transmits through the beam splitter 102 and is collected by the imaging component 104 without being interfered by the original light ray L0 or the first light ray L1.

[0037] The imaging component 104 collects the reflected second light ray L2 to form a first Moiré fringe. The Moiré fringe is an interference phenomenon observed in optical experiments, and its optical principle is related to the wave nature of light and light interference. When two sets of parallel periodic fringes are superimposed, a new fringe pattern with alternating bright and dark areas is generated, and this pattern is called a Moiré fringe. The Moiré fringe can magnify a small relative displacement, and it has high sensitivity, which is beneficial to improving the accuracy of alignment measurement. In the embodiment of the present application, through the first Moiré fringe formed by the second light ray reflected by the first alignment mark and the second alignment mark, it is possible to directly determine whether the first alignment mark 106 and the second alignment mark 108 are aligned, and calculate the alignment deviation between the first alignment mark 106 and the second alignment mark 108.

[0038] It can be understood that the above-mentioned first alignment mark and second alignment mark can be any shape that can reflect light to form a Moiré fringe, such as a bar-shaped or circular grating shape.

[0039] In addition, the above-mentioned first light ray L1 needs to pass through the first wafer 105 and irradiate the second wafer 107 and be reflected by the second alignment mark 108 and then pass through the first wafer 105 again. Therefore, the first light ray L1 has a certain transmittance. For example, its wavelength belongs to the wavelength range that can pass through the wafer. Taking a silicon wafer as an example, the first light ray can be an infrared light or a ray with a wavelength greater than infrared light, which is collectively referred to as a light ray in the embodiment of the present application. It can be understood that in order to obtain the first light ray L1 with the above-mentioned transmittance, the light source component 101 needs to provide an original light ray L0 with this characteristic.

[0040] It should be emphasized that the wafers to be measured can be the first wafer and the second wafer before bonding connection, or the first wafer and the second wafer that have been bonded.

[0041] The wafer alignment measurement device provided by the embodiment of the present application, on the one hand, uses a light ray with good penetrability relative to the first wafer 105 or the second wafer 107, so that it can pass through the first wafer 105 and propagate to the second alignment mark 108 of the second wafer, and it is possible to directly observe or measure whether the first alignment mark 106 and the second alignment mark 108 are aligned, simplifying the alignment recognition steps and reducing the measurement error caused by separate observation. On the second hand, by using the first light ray L1 and the second light ray L2 with different polarization directions, it is possible to realize the transmission and reflection selection of the incident light and the reflected light of the alignment mark (the first alignment mark or the second alignment mark). The imaging component collects all the reflected second light rays, which can increase the imaging quality of the first Moiré fringe and is beneficial to improving the extraction of alignment information. On the third hand, by using the first Moiré fringe, the deviation between the alignment marks can be magnified, which is beneficial to improving the accuracy of alignment measurement.

[0042] In some embodiments, as Figure 2 shown, the alignment measurement device 100 further includes: A data processing device 201, connected to the imaging component 104, is configured to determine whether the first alignment mark and the second alignment mark are aligned according to the first Moiré fringe and a preset second Moiré fringe.

[0043] For the determined first alignment mark 106 and second alignment mark 108, a Moiré fringe with a fixed pattern corresponding to the alignment state can be obtained, that is, the preset second Moiré fringe. The preset second Moiré fringe can be stored in the data processing device 201, and it can be obtained through prior calibration or simulation. When the first Moiré fringe collected by the imaging component is consistent with the second Moiré fringe, it indicates that the first alignment mark and the second alignment mark are already aligned.

[0044] It can be understood that Figure 2 the data processing 201 shown distributed along the X-axis with the imaging component 104 is only for illustrative purposes, and the embodiments of the present application do not limit the specific position of the data processing component.

[0045] In some embodiments, as Figure 3 shown, the imaging component includes a tube lens 301 and an image sensor 302; The tube lens 301 is located between the beam splitter 102 and the image sensor 302, and is configured to converge the second light beam passing through the beam splitter 102; The image sensor 302 is configured to collect the first Moiré fringe formed by the second light beam.

[0046] The tube lens 301 converges the second light beam passing through the beam splitter 102 and focuses the second light beam onto the imaging plane, so that a clear image of the first Moiré fringe can be formed on the image sensor 302.

[0047] The specific type of the image sensor 302 can be reasonably selected according to the wavelength band of the original light beam L0 emitted by the light source component 101 to further improve the sensitivity and response ability of the image sensor 302 under this light condition.

[0048] In some embodiments, continuing to refer to Figure 3 , the alignment measurement device 100 further includes: An objective lens assembly 303, located between the polarizer 103 and the first wafer 105, is configured to focus the light beam to a preset position between the first alignment mark and the second alignment mark.

[0049] That is, the focusing plane position of the objective lens assembly 303 can be set at a preset position between the first alignment mark 106 and the second alignment mark 108, so that in the third direction (the positive direction of the Z axis), both the first alignment mark 106 and the second alignment mark 108 are within the depth of field of the objective lens assembly 303. Here, the preset position can be any position between the position where the first alignment mark 106 is located and the position where the second alignment mark 108 is located. In practical applications, the position with the best imaging effect can be found through multiple tests as the above-mentioned preset position.

[0050] In this way, through one-time focusing, the first light ray L1 can be reflected on the surfaces of the first alignment mark 106 and the second alignment mark 108, and the corresponding first Moiré fringe can be obtained.

[0051] In some embodiments, as Figure 4 shown, the light source assembly 101 includes a laser emitter 401; The laser emitter 401 is used to emit an original light ray L0 with a wavelength longer than the visible light wavelength.

[0052] Light rays within the visible light range (for example, with a wavelength less than 780 nm) cannot penetrate the silicon wafer, and it is not possible to effectively observe or measure the stacked silicon wafers using visible light. Generally, the longer the wavelength of the original light ray L0, the stronger its penetration performance. By extending the wavelength band of the original light ray to the infrared band (for example, with a wavelength greater than 1200 nm), the light ray can propagate to the surfaces of the first alignment mark and the second alignment mark, enabling direct observation of the alignment state of the wafer. Moreover, the stronger the penetration performance, the more light rays reflected by the alignment marks, which is more conducive to improving the imaging quality of the imaging assembly.

[0053] In some embodiments, the light source assembly 101 may further include a beam expander, which can be disposed between the laser emitter 401 and the beam splitter 102 to modulate the light ray into parallel light. Parallel light can provide a uniform illumination effect, increase the consistency of the brightness distribution, and is conducive to improving the imaging quality of the first Moiré fringe.

[0054] Furthermore, a filter, a polarizer, and a half-wave plate can be added between the beam expander and the beam splitter to adjust the bandwidth, polarization, and energy of the parallel light respectively. Parallel light can better cooperate with components such as the filter, the polarizer, and the half-wave plate, further ensuring that the performance of these optical components is fully exerted.

[0055] It can be understood that the embodiments of the present application do not limit the specific positions of components such as the laser emitter, the beam expander, the filter, the polarizer, and the half-wave plate, as long as the first light ray L1 reflected by the beam splitter 102 propagates along the first direction.

[0056] In some embodiments, asFigure 5A As shown, the first alignment mark 106 includes a plurality of first grating stripes 501 arranged along a fourth direction, or as Figure 5B shown, the first alignment mark 106 includes a plurality of first grating annular patterns 502 in the form of concentric circles; wherein, the fourth direction is parallel to the surface of the first wafer; And / or, the second alignment mark includes a plurality of second grating stripes arranged along a fifth direction, or the second alignment mark includes a plurality of second grating annular patterns in the form of concentric circles; wherein, the fifth direction is parallel to the surface of the second wafer.

[0057] The plurality of first grating stripes 501 arranged along the fourth direction can be used to achieve the alignment of the wafer in the fourth direction. The plurality of second grating stripes arranged along the fifth direction can be used to achieve the alignment of the wafer in the fifth direction. It should be noted that the arrangement directions of the first grating stripes and the second grating stripes in the alignment state are the same, that is, the fourth direction is parallel to the fifth direction.

[0058] In some embodiments, as Figure 6 shown, to achieve the alignment of the first wafer and the second wafer in the XOY plane, a set of first grating stripes can be respectively arranged on the first wafer along the X-axis and the Y-axis directions. Similarly, a set of second grating stripes can be respectively arranged on the second wafer along the X-axis and the Y-axis directions. It should be noted that the arrangement along the X-axis and the Y-axis directions is only for illustrative purposes, and the embodiments of the present application do not limit the arrangement directions of the two sets of grating stripes, as long as their arrangement directions are not parallel to each other. Moreover, the two sets of first grating stripes in different directions do not affect each other and can be set independently.

[0059] In some embodiments, along the fourth direction, the first grating stripes are arranged according to a first period P1; along the fifth direction, the second grating stripes are arranged according to a second period P2; The absolute value of the difference between the first period P1 and the second period P2 is greater than 0 and less than or equal to a preset first threshold.

[0060] Wherein, the first threshold can be determined according to the first period or the second period. Exemplarily, the first threshold can be determined as one-half of the first period. In practical applications, by reducing the difference between the first period and the second period, the pitch of the first Moiré fringe can be increased, and the resolution of the alignment measurement can be improved.

[0061] Figure 7 shows a comparison schematic diagram of the first alignment mark and the second alignment mark. As Figure 7As shown, the first grating stripe 501 is a rectangle with a width of a1. A plurality of first grating stripes 501 are arranged along the positive direction of the X-axis, and the distance between any two adjacent first grating stripes 501 is b1. Then the first period P1 is the sum of the width a1 and the distance b1. Similarly, the second grating stripe 503 is a rectangle with a width of a2. A plurality of second grating stripes 503 are arranged along the positive direction of the X-axis, and the distance between any two adjacent second grating stripes 503 is b2. Then the second period P2 is the sum of the width a2 and the distance b2. Then the absolute value of the difference between the first period P1 and the second period P2 is |a1 + b1 - a2 - b2|.

[0062] Figure 8 The first Moiré fringe in different alignment states is shown, where (a) is the first Moiré fringe when the first alignment mark and the second alignment mark are in the aligned state, and (b) is the first Moiré fringe when the first alignment mark and the second alignment mark are in the unaligned state. When two grating stripes with similar periods and a small deviation coincide, that is, when the first alignment mark 106 and the second alignment mark 108 coincide, a first Moiré fringe with dark stripes 801 of different widths will be generated due to the period deviation. If there is a relative shift between the two grating stripes, the bright and dark positions of the first Moiré fringe (such as the position of the dark stripe 801) will also change. By comparing the measured first Moiré fringe with the second Moiré fringe in the aligned state, the relative shift amount and the shift direction between the two grating stripes can be deduced inversely.

[0063] In some embodiments, as Figure 9 shown, along the first direction, there is a first distance Z1 between the first alignment mark 106 and the second alignment mark 108; The difference between the width of the first grating stripe and the first distance is less than a preset second threshold; the difference between the width of the first grating ring pattern and the first distance is less than a preset third threshold; and / or The difference between the width of the second grating stripe and the first distance is less than the second threshold; the difference between the width of the first grating ring pattern and the first distance is less than the third threshold.

[0064] The second threshold can be determined according to the width or the first period of the grating stripe (the first grating stripe or the second grating stripe), and the third threshold can be determined according to the width or the period of the grating ring pattern (the first grating ring pattern or the second grating ring pattern). Exemplarily, the first distance Z1 and the width of the grating stripe can belong to the same order of magnitude range, or the first distance Z1 and the width of the grating ring pattern belong to the same order of magnitude range. Or the difference between the width of the first grating stripe and the first distance Z1 is less than the first period P1. Taking the case where both the first distance Z1 and the width of the grating stripe are in the micrometer level as an example, at this time, the light reflected by the first alignment mark and the second alignment mark can be regarded as the 0th order diffracted light, reducing the influence of the first Moiré fringe by the "Talbot" effect, total reflection effect, diffraction effect, etc. Among them, the "Talbot" effect refers to the phenomenon that the grating forms a self-imaging at a specific distance. Total reflection refers to the phenomenon that when light travels from an optically denser medium to an optically thinner medium, when the incident angle is greater than the critical angle, the light is completely reflected back to the optically denser medium. The diffraction effect refers to the phenomenon that light deviates from the straight-line propagation when it encounters an obstacle or passes through a slit.

[0065] In some embodiments, the material of the first grating stripe and / or the material of the second grating stripe includes a metal material.

[0066] Similarly, the material of the first grating ring pattern and / or the material of the second grating ring pattern also includes a metal material.

[0067] For example, metal materials such as copper or aluminum have good reflection performance. Exemplarily, in the infrared light range, the reflectivity of aluminum can exceed 90%. A grating with good reflection performance can significantly reduce the loss of light energy and further improve the performance of alignment measurement.

[0068] This application also provides the following embodiments: Such as Figure 10As shown, the first wafer 105 and the second wafer 107 are both placed on the sample stage 1001 of the alignment measurement device 100. The wafer alignment measurement device 100 determines whether the first wafer and the second wafer are aligned based on the first alignment mark 106 on the first wafer 105 and the second alignment mark 108 on the second wafer 107. Specifically, the light source assembly 101 of the wafer alignment measurement device 100 can provide infrared light, and the infrared light propagates along the negative X-axis direction to the beam splitter 102. The beam splitter 102 separates the infrared light into a first linearly polarized light with a first polarization direction (i.e., a first light ray L1 with a first polarization direction) and a second linearly polarized light with a second polarization direction. The plane where the beam splitter 102 is located forms a 45° angle with the XOY plane. The first light ray L1 is reflected by the beam splitter 102 and propagates along the negative Z-axis direction to the polarization element. That is, the first angle between the original light ray L0 incident on the beam splitter and the first light ray L1 is 90°. The polarization element is a quarter-wave plate 113. The first light ray L1 with a first polarization direction becomes a first circularly polarized light C1 after passing through the quarter-wave plate 113. The first circularly polarized light C1 forms a second circularly polarized light C2 after being reflected by the first alignment mark 106 and the second alignment mark 108. The propagation directions of the first circularly polarized light C1 and the second circularly polarized light C2 are opposite. Since the chirality of the circularly polarized light will be reversed after reflection, that is, the chirality of the first circularly polarized light C1 and the second circularly polarized light C2 is opposite. When the second circularly polarized light C2 propagates upward along the positive Z-axis direction and passes through the quarter-wave plate 113, it becomes a second light ray L2 with a second polarization direction. Among them, the first polarization direction and the second polarization direction are perpendicular to each other. The second light ray L2 with a second polarization direction can pass through the beam splitter 102 smoothly and is collected by the image sensor 302 after being focused by the tube lens 301.

[0069] The data processing component 201 is connected to the image sensor 302, analyzes and compares the first Moiré fringe collected by the image sensor 302 with a preset second Moiré fringe, and determines the offset situation between the first alignment mark 106 and the second alignment mark 108. Exemplarily, as Figure 11 shown, according to the first Moiré fringe, a measured signal curve is extracted, and by comparing the measured signal curve with the theoretical signal curve corresponding to the second Moiré fringe, the offset situation between the first alignment mark 106 and the second alignment mark 108 can be determined.

[0070] Specifically, by comparing the measured signal curve corresponding to the first Moiré fringe with the theoretical signal curve corresponding to the second Moiré fringe, the offset Δ at the peak positions of the two curves is obtained. Among them, the positive and negative signs of the offset Δ can be defined by the offset direction. Then, the actual translational offset δ between the first alignment mark 106 and the second alignment mark 108 can be determined through the following magnification formula (1): δ = Δ / (M f * M opt ) (1) Among them, M opt represents the magnification of the imaging component, and M f represents the magnification of the Moiré fringe.

[0071] It should be noted that the magnification M of the imaging component opt includes the magnification of the image processing and the magnification of the optical lens groups such as the objective lens assembly 303 and the tube lens 301. The magnification M of the Moiré fringe f refers to the magnification of the Moiré fringe displacement relative to the relative displacement between the grating fringes.

[0072] The number of unilateral sampling points N and the field of view FOV of the image sensor 302 can be determined according to the following formulas (2) and (3) respectively: N = M opt / η CCD (2) FOV = W / η CCD (3) Among them, η CCD represents the resolution of the image sensor 302, and W represents the image plane width of the image sensor 302.

[0073] In practical applications, the magnification M of the Moiré fringe can be controlled by adjusting the specific parameters of the first alignment mark 106 and the second alignment mark 108, such as adjusting the difference between the first period P1 of the first grating fringe and the second period P2 of the second grating fringe. f Specifically, the magnification M of the Moiré fringe f can be determined according to the following formula (4): M f =(P1 + P2) / (P1 - P2) (4) At this time, the displacement resolution η of the alignment measurement device can be determined according to the magnification M of the imaging component opt , the magnification M of the Moiré fringe f and the resolution η of the image sensor 302 CCD . Specifically, the displacement resolution η of the alignment measurement device can be determined according to the following formula (5): η = η CCD / (M f *M opt ) (5) In addition, the effective alignment range of the first Moiré fringe, that is, the maximum displacement range that can achieve precise alignment, can also be controlled by adjusting the first period P1 and the second period P2. Specifically, the effective alignment range R can be determined according to the following formula (6): R = ±P F / 4 = ±(P1 * P2) / (4(P1 - P2)) (6) Based on the same inventive concept, an embodiment of the present application provides a wafer alignment measurement method, as Figure 12 shown, the wafer alignment measurement method includes the following steps: Step S101: Use a light source assembly to provide original light propagating in the second direction.

[0074] Step S102: After the original light is reflected by the beam splitter, it propagates in the first direction through the polarizer to the first alignment mark on the first wafer, and then passes through the first wafer and propagates to the second alignment mark on the second wafer.

[0075] Among them, the light reflected by the beam splitter is the first light with a first polarization direction; the light reflected by the first alignment mark and the second alignment mark is the second light, and the second light has a second polarization direction after passing through the polarizer; the second polarization direction is different from the first polarization direction.

[0076] Step S103: Use an imaging assembly to collect the first Moiré fringe formed by the second light with the second polarization direction after the beam splitter.

[0077] Among them, the first Moiré fringe is used to determine whether the first alignment mark and the second alignment mark are aligned.

[0078] The imaging assembly, the beam splitter, and the polarizer are arranged in sequence in the first direction, and the light source assembly and the beam splitter are arranged in the second direction; the first direction and the second direction have a first included angle.

[0079] In some embodiments, the alignment measurement method further includes the following steps: Determine the translational offset between the first alignment mark and the second alignment mark according to the first Moiré fringe and a preset second Moiré fringe; Horizontally move the first wafer and / or the second wafer according to the translational offset so that the first alignment mark is aligned with the second alignment mark.

[0080] Since there is a strict correspondence between the movement amount and movement direction of the first Moiré fringe and the translational offset and offset direction between the first alignment mark and the second alignment mark, according to the first Moiré fringe and the preset second Moiré fringe, it can be determined how to adjust the direction and movement distance of the wafer to be moved so that the first alignment mark is aligned with the second alignment mark.

[0081] In some embodiments, the alignment measurement method further includes the following steps: Determine the offset angle between the first alignment mark and the second alignment mark according to the normal vector of the first alignment mark and the normal vector of the second alignment mark; Adjust the horizontal rotation angle of the first wafer and / or the second wafer according to the offset angle so that the first alignment mark and the second alignment mark are parallel to the same plane.

[0082] Based on the same inventive concept, an embodiment of the present application provides a bonding device. As Figure 13 shown, the bonding device 200 includes the alignment and measurement device 100 and the control component 300 of any one of the above, and the control component 300 is configured to move the first wafer 105 and / or the second wafer 107 to be bonded according to the measurement information of the alignment and measurement device 100, so that the first alignment mark 106 and the second alignment mark 108 are aligned.

[0083] It should be noted that manual alignment or automatic alignment can be performed according to the measurement information of the alignment and measurement device, so that the first wafer and the second wafer meet the alignment accuracy requirements for bonding.

[0084] In some embodiments, the control component 300 is connected to the data processing component 201 in the alignment and measurement device 100, and moves the wafers to be bonded according to the measurement information output by the data processing component 201, so that the collected first Moiré fringe is the same as the preset second Moiré fringe, that is, the first alignment mark and the second alignment mark are aligned.

[0085] Based on the same inventive concept, an embodiment of the present application provides a semiconductor structure. As Figure 14 shown, the semiconductor structure 400 includes a first wafer 105; The first wafer 105 includes a first alignment mark 106; the first alignment mark 106 includes a plurality of first grating stripes arranged in a fourth direction, or the first alignment mark 106 includes a plurality of first grating rings in a concentric circle; The first alignment mark 106 is configured to jointly reflect light with a second alignment mark located on the second wafer to form a first Moiré fringe; the first Moiré fringe is used to determine whether the first alignment mark 106 and the second alignment mark are aligned.

[0086] For the relevant details of the first alignment mark 106 and the second alignment mark 108, reference can be made to the above, and details will not be repeated here.

[0087] In some embodiments, as Figures 15A to 15B shown, the first wafer 105 further includes a first silicon substrate 1501 and at least one first transmissive layer 1502; The first alignment mark 106 is located on a side of the first transmissive layer 1502 close to the first silicon substrate 1501; or the first alignment mark 106 is located on a side of the first transmissive layer 1502 away from the first silicon substrate 1501; The light transmittance of the first transmissive layer 1502 is greater than or equal to a preset first transmittance; The light transmittance of the first silicon substrate 1501 is greater than or equal to a preset second transmittance.

[0088] Along the light incident direction (e.g., along the first direction), if there is a material with high reflection characteristics such as metal above the first alignment mark, the pattern generated by the alignment mark will be shielded. If there is a material with high reflection characteristics such as metal below the second alignment mark, redundant reflected light will be generated, resulting in background noise. By providing a first transmissive layer on the upper or lower side of the first alignment mark, it can be ensured that there are no other metal wiring patterns in the upper or lower area of the first alignment mark, which will not affect the acquisition of the first Moiré fringe.

[0089] It can be understood that the light in the "light transmittance" refers to the light within the range of the original light wavelength. A first transmissive layer can be provided on both the upper and lower sides of the first alignment mark 106.

[0090] In some embodiments, the first transmittance is greater than or equal to 85%; and / or, the second transmittance is greater than or equal to 50%.

[0091] In some embodiments, as Figure 16A or Figure 16B shown, the semiconductor structure 400 further includes a second wafer 107; The first wafer 105 is bonded to the second wafer 107; The second alignment mark 108 includes a plurality of second grating stripes arranged along the fifth direction, or the second alignment mark includes a plurality of second grating ring patterns in the form of concentric circles.

[0092] In some embodiments, continuing to refer to Figure 16A and Figure 16B , the second wafer 107 further includes a second silicon substrate 1601 and at least one second transmissive layer 1602; the second alignment mark 108 is located on the side of the second transmissive layer 1602 close to the second silicon substrate 1601, or the second alignment mark 108 is located on the side of the second transmissive layer 1602 away from the second silicon substrate 1601; The light transmittance of the second transmissive layer 1602 is greater than or equal to the first transmittance; The light transmittance of the second silicon substrate 1601 is greater than or equal to the second transmittance.

[0093] In some embodiments, after the bonding connection, there is a first transmissive layer and / or a second transmissive layer between the first alignment mark and the second alignment mark. It can be understood that in these semiconductor structures after the bonding connection, the patterns of the first alignment mark and the second alignment mark will not be affected by the wafer bonding process, and alignment measurement can also be performed according to the first alignment mark and the second alignment mark after the bonding connection.

[0094] In other embodiments, the upper surface of the first alignment mark is the upper surface of the first wafer, and the upper surface of the second alignment mark is the upper surface of the second wafer. AsFigure 16B As shown, after the bonding connection, the first alignment mark 106 contacts and abuts against the second alignment mark 108.

[0095] In some embodiments, the first transmissive layer includes a silicon dioxide material and / or a silicon nitride material.

[0096] Similarly, the second transmissive layer includes a silicon dioxide material and / or a silicon nitride material.

[0097] Light can be transmitted through the silicon dioxide material and / or the silicon nitride material to the surface of the first alignment mark or the second alignment mark. Among them, the transmittance of the silicon dioxide material and the silicon nitride material in the near-infrared light range is better than that in the far-infrared light. Selecting near-infrared light as the original light can further improve the quality of the first Moiré fringe.

[0098] It should be noted that the silicon dioxide material and / or the silicon nitride material are only used for illustrative purposes. The embodiments of the present application do not limit the specific materials of the first transmissive layer or the second transmissive layer, as long as light can be transmitted through them to the surfaces of the first alignment mark and the second alignment mark.

[0099] In some embodiments, the first wafer includes a plurality of first chip regions and a scribe lane region located between the first chip regions; the first alignment mark is located within the scribe lane region.

[0100] Similarly, the second wafer includes a plurality of first chip regions and a scribe lane region located between the first chip regions; the second alignment mark is located within the scribe lane region of the second wafer.

[0101] The scribe lane region is a region on the wafer (the first wafer or the second wafer) used for cutting and separating chips. Setting the alignment mark (the first alignment mark or the second alignment mark) on the scribe lane region will not interfere with the device structure and function of the chip region of the wafer, and can ensure the integrity and reliability of the chip region.

[0102] In addition, since the scribe lane region can divide the wafer relatively evenly, multiple alignment marks (multiple first alignment marks or multiple second alignment marks) can be set in different scribe lane regions. By analyzing the offset conditions of the alignment marks located at different positions, the overall alignment status of the first wafer and the second wafer can be judged more accurately, and the alignment measurement accuracy of the wafer can be further improved.

[0103] In addition, since both the first alignment mark and the second alignment mark are located within the dicing street area and will be removed during the dicing process, there is no need to specifically consider the bonding quality of the wafer interface within the dicing street area. Even if both the first alignment mark and the second alignment mark are provided on the wafer surface, different metal materials can be used to form the first alignment mark and the second alignment mark. That is to say, even if the first alignment mark and the second alignment mark cannot be bonded and connected during the bonding process, it will not affect the quality of the final chip or product.

[0104] The various embodiments / implementations provided in this application can be combined with each other without contradiction.

[0105] The above are only the preferred embodiments of this application and are not used to limit this application. For those skilled in the art, this application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims

1. A wafer alignment measurement device, characterized in that: include: A light source assembly, a beam splitter, a polarizing element, and an imaging assembly; wherein the imaging assembly, the beam splitter, and the polarizing element are sequentially arranged along a first direction; the light source assembly and the beam splitter are arranged along a second direction; wherein the first direction and the second direction have a first angle; The light source assembly is used to provide original light propagating along the second direction; The beam splitter is used to reflect the original light based on the polarization direction; wherein the reflected light is a first light with a first polarization direction; The first light propagates along the first direction through the polarizing element to a first alignment mark located on the first wafer, and propagates through the first wafer to a second alignment mark located on the second wafer; The second light reflected by the first alignment mark and the second alignment mark has a second polarization direction after passing through the polarizer; the second polarization direction is different from the first polarization direction; The second light with a second polarization direction transmits the beam splitter along a third direction and propagates to the imaging component; wherein the third direction is opposite to the first direction; the imaging component is used to collect the first moiré fringes formed by the second light; the first moiré fringes are used to determine whether the first alignment mark and the second alignment mark are aligned.

2. The alignment measurement device according to claim 1, characterized in that: Also includes: A data processing device is connected to the imaging component, and is used to determine whether the first alignment mark and the second alignment mark are aligned according to the first moiré fringes and preset second moiré fringes.

3. The alignment measurement device according to claim 1, characterized in that: The imaging assembly includes a tube lens and an image sensor; The tube lens is located between the beam splitter and the image sensor, and is used to converge the second light passing through the beam splitter; The image sensor is used to collect the first moiré fringes formed by the second light.

4. The alignment measurement device according to claim 1, characterized in that: Also includes: An objective lens assembly is located between the polarizing element and the first wafer, and is used to focus light to a preset position between the first alignment mark and the second alignment mark.

5. The alignment measurement device according to claim 1, characterized in that: The light source assembly includes a laser emitter; The laser emitter is used to emit the original light with a wavelength greater than that of visible light.

6. The alignment measurement device according to claim 1, characterized in that: The first alignment mark includes a plurality of first grating stripes arranged along a fourth direction, or the first alignment mark includes a plurality of first grating rings in the form of concentric circles; the fourth direction is parallel to the surface of the first wafer; And / or, the second alignment mark includes a plurality of second grating stripes arranged along a fifth direction, or the second alignment mark includes a plurality of second grating rings in the form of concentric circles; and the fifth direction is parallel to the surface of the second wafer.

7. The alignment measurement device according to claim 6, characterized in that: Along the fourth direction, the first grating stripes are arranged according to a first period; Along the fifth direction, the second grating stripes are arranged according to a second period; An absolute value of a difference between the first period and the second period is greater than 0 and less than or equal to a preset first threshold.

8. The alignment measurement device according to claim 6, characterized in that: Along the first direction, there is a first distance between the first alignment mark and the second alignment mark; The difference between the width of the first grating stripe and the first distance is smaller than a preset second threshold; the difference between the width of the first grating ring pattern and the first distance is smaller than a preset third threshold; and / or The difference between the width of the second grating stripes and the first distance is smaller than the second threshold; the difference between the width of the first grating rings and the first distance is smaller than the third threshold.

9. The alignment measurement device according to claim 6, characterized in that: The material of the first grating stripes and / or the material of the second grating stripes include a metal material.

10. A bonding device, characterized in that: comprising the alignment measurement device and control assembly according to any one of claims 1 to 9, The control component is used for moving the first wafer and / or the second wafer to be bonded according to the measurement information of the alignment measurement device, so that the first alignment mark and the second alignment mark are aligned.

11. A semiconductor structure, characterized in that: including a first wafer; The first wafer includes a first alignment mark; the first alignment mark includes a plurality of first grating stripes arranged along a fourth direction, or the first alignment mark includes a plurality of first grating rings in the form of concentric circles; The first alignment mark is used to reflect light together with the second alignment mark located on the second wafer to form a first moiré fringe; the first moiré fringe is used to determine whether the first alignment mark and the second alignment mark are aligned.

12. The semiconductor structure according to claim 11, characterized in that: The first wafer also includes a first silicon substrate and at least one first transmission layer; The first alignment mark is located on a side of the first transmission layer close to the first silicon substrate; or the first alignment mark is located on a side of the first transmission layer far from the first silicon substrate; The transmittance of the first transmission layer to light is greater than or equal to a preset first transmittance; The transmittance of the first silicon substrate to light is greater than or equal to a preset second transmittance.

13. The semiconductor structure according to claim 12, characterized in that: The first transmittance is greater than or equal to 85%; and / or the second transmittance is greater than or equal to 50%.

14. The semiconductor structure according to claim 12, characterized in that: Also comprising the second wafer; The first wafer is bonded to the second wafer; The second alignment mark includes a plurality of second grating stripes arranged along a fifth direction, or the second alignment mark includes a plurality of second grating rings in the form of concentric circles.

15. The semiconductor structure according to claim 14, characterized in that: The second wafer further includes a second silicon substrate and at least one second transmission layer; the second alignment mark is located on a side of the second transmission layer close to the second silicon substrate, or the second alignment mark is located on a side of the second transmission layer away from the second silicon substrate; The transmittance of the second transmission layer to light is greater than or equal to the first transmittance; The transmittance of the second silicon substrate to light is greater than or equal to the second transmittance.

16. The semiconductor structure according to claim 11, characterized in that The first transmission layer includes silicon dioxide material and / or silicon nitride material.

17. The semiconductor structure according to claim 11, characterized in that The first wafer includes a plurality of first chip regions and a scribe line region between the first chip regions; and the first alignment mark is located in the scribe line region.

18. A wafer alignment measurement method, characterized in that: include: Using the light source assembly to provide original light propagating along a second direction; After being reflected by the beam splitter, the original light propagates along a first direction through the polarizer to a first alignment mark located on the first wafer, and propagates through the first wafer to a second alignment mark located on the second wafer; The light reflected by the beam splitter is a first light with a first polarization direction; the light reflected by the first alignment mark and the second alignment mark is a second light, and the second light has a second polarization direction after passing through the polarizer; the second polarization direction is different from the first polarization direction; Using an imaging component to collect first moiré fringes formed by the second light having a second polarization direction after passing through the beam splitter; the first moiré fringes are used to determine whether the first alignment mark and the second alignment mark are aligned; The imaging component, the beam splitter and the polarizing component are sequentially arranged along a first direction, and the light source component and the beam splitter are arranged along a second direction; the first direction and the second direction have a first angle.

19. The alignment measurement method according to claim 18, characterized in that: Also includes: Determining a translation offset between a first alignment mark and a second alignment mark according to the first moiré fringe and a preset second moiré fringe; The first wafer and / or the second wafer is horizontally moved according to the translation offset so that the first alignment mark is aligned with the second alignment mark.

20. The alignment measurement method according to claim 18, characterized in that: Also includes: Determining an offset angle between the first alignment mark and the second alignment mark according to a normal vector of the first alignment mark and a normal vector of the second alignment mark; The horizontal rotation angle of the first wafer and / or the second wafer is adjusted according to the offset angle, so that the first alignment mark and the second alignment mark are parallel to the same plane.

Images