TWI879236B - Apparatus and method for wafer bonding alignment and detection - Google Patents

Abstract

The present application relates to an apparatus and method for wafer bonding alignment and detection. In one embodiment of the present application, the apparatus for wafer bonding alignment and detection comprises: a light source configured to generate a light beam, the light beam being obliquely incident on a mark on a first wafer surface; and an imaging device configured to photograph the mark by receiving at least a portion of diffusely reflected light generated by the light beam at the mark.

Description

Apparatus and method for wafer bonding alignment and detection

This application relates to the field of semiconductor processing, and more particularly to devices and methods for wafer bonding alignment and detection.

Wafer bonding plays an increasingly important role in semiconductor chip production. Wafer bonding technology can combine two homogeneous or heterogeneous wafers into a whole by bonding their molecules under the action of external force.

For wafer bonding technology, wafer bonding alignment accuracy is an important characteristic parameter. With the development of chip technology, the integration of chips is getting higher and higher, and the requirements for wafer bonding alignment accuracy are gradually increasing. After the wafer bonding is completed, it is also necessary to detect the bonding alignment accuracy of the two wafers.

There are usually alignment marks on the bonding surface of the wafer. The surface where the alignment mark is located can also be called the "front side" of the wafer, and the surface without the mark opposite to the "front side" can also be called the "back side" of the wafer. Wafer bonding alignment and detection technology requires imaging of the alignment marks on the wafer surface. For example, this technology can capture and locate the alignment marks on the upper and lower wafers respectively, obtain the position difference of the two marks to align the wafer, and can capture and locate the two marks after bonding is completed to detect the degree of alignment deviation of the wafer.

When capturing and positioning images of the mark, backlight illumination can be used, but its application scenarios are limited. For example, when the back side of the wafer is coated with a film layer with low light transmittance, backlight illumination cannot be used. Bright field illumination can solve the above scene limitation problem, but when bright field illumination is used, the reflected light generated by the upper surface of the wafer and the reflected light generated by the bonding surface will enter the imaging device, and the intensity of the reflected light generated by the upper surface of the wafer is much greater than the intensity of the reflected light generated by the bonding surface, which will cause the imaging device to be unable to clearly image the alignment mark on the bonding surface.

Therefore, it is necessary to develop a device and method for wafer bonding alignment and detection to solve the above problems.

This application at least provides a device and method for wafer bonding alignment and detection to obtain clear imaging of wafer identification and the application scenarios are not limited.

Some embodiments of the present application provide a device for wafer bonding alignment and detection, comprising: a light source configured to generate a light beam, the light beam being obliquely incident on a mark on a first wafer surface; and an imaging device configured to photograph the mark by receiving at least a portion of diffusely reflected light generated by the light beam at the mark.

According to some embodiments of the present application, the light source is an infrared light source.

According to some embodiments of the present application, the device further comprises a converging lens or a converging lens set, and the converging lens or the converging lens set is configured to converge the light beam emitted from the light source.

According to some embodiments of the present application, the converged light beam is substantially focused on the mark.

According to some embodiments of the present application, the device further comprises a first polarizer and a second polarizer, wherein the light beam passes through the second wafer surface and then is emitted toward the mark, the first polarizer is configured to make the light beam incident on the second wafer surface linearly polarized light, and the second polarizer is configured to at least partially block the specular reflection light generated by the light beam on the second wafer surface from entering the imaging device.

According to some embodiments of the present application, the polarization direction of the second polarizer is perpendicular to the polarization direction of the mirror-reflected light.

According to some embodiments of the present application, the device further comprises one or more auxiliary light sources, which are configured to generate one or more corresponding auxiliary light beams, each of which is inclined toward the mark.

According to some embodiments of the present application, the one or more auxiliary light sources and the light source are arranged in a ring shape relative to the imaging device.

Some other embodiments of the present application provide a method for wafer bonding alignment and detection, which includes: providing a wafer having a mark on a first wafer surface; providing a light source configured to generate a light beam, the light beam being inclined toward the mark; and providing an imaging device configured to photograph the mark by receiving at least a portion of diffusely reflected light generated by the light beam at the mark.

According to some embodiments of the present application, the method further includes collecting the positioning information of the image of the above-mentioned mark after photographing the above-mentioned mark.

According to some embodiments of the present application, the wafer is a first wafer, the mark is a first mark, the light beam is a first light beam, and the method further includes: providing a second wafer having a second mark on a second wafer surface, wherein the second wafer surface is arranged opposite to the first wafer surface; generating a second light beam obliquely incident on the second mark by the light source; and receiving at least a portion of the diffusely reflected light generated by the second light beam at the second mark by the imaging device to photograph the second mark.

According to some embodiments of the present application, the method further includes: comparing the photographed first identification with the second identification; and adjusting the relative position of the first wafer and the second wafer based on the comparison result so that the first identification and the second identification are aligned with each other.

According to some embodiments of the present application, the wafers are the first wafer and the second wafer that have been bonded, the surface of the first wafer is the bonding surface between the first wafer and the second wafer, and the identification includes the first identification of the first wafer and the second identification of the second wafer.

According to some embodiments of the present application, the method further includes: comparing the photographed first identification with the second identification; and calculating the offset of the bonding alignment between the first wafer and the second wafer based on the comparison result.

According to some embodiments of the present application, the light source is an infrared light source.

According to some embodiments of the present application, the method further comprises providing a converging lens or a converging lens set so that the light beam is converged and directed toward the mark.

According to some embodiments of the present application, the converged light beam is substantially focused on the mark.

According to some embodiments of the present application, the method further includes providing a first polarizer and a second polarizer, wherein the light beam passes through the second wafer surface and then is directed toward the mark, the first polarizer is configured to make the light beam incident on the second wafer surface linearly polarized light, and the second polarizer is configured to at least partially block the specular reflection light generated by the light beam on the second wafer surface from entering the imaging device.

According to some embodiments of the present application, the polarization direction of the second polarizer is perpendicular to the polarization direction of the mirror-reflected light.

According to some embodiments of the present application, the method further includes providing one or more auxiliary light sources to generate corresponding one or more auxiliary light beams, each of the one or more auxiliary light beams being inclined toward the mark.

According to some embodiments of the present application, the one or more auxiliary light sources and the light source are arranged in a ring shape relative to the imaging device.

The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects and advantages will be apparent from the above description and drawings and the scope of the application.

100:System

101: First Wafer

101': First sign

102: Second wafer

102': Second sign

103: Membrane layer

104: Light source

104': Beam

105: Imaging device

200:System

201: First Wafer

201': First sign

202: Second wafer

2022: Upper surface

202': Second sign

203': Beam

203":Reflected light

204: Half-mirror

300: System

301: First wafer

301': First identification

302: Second wafer

302': Second identification

3022: Upper surface

303: Light source

303': Beam

304: Converging lens or/and converging lens group

304': Converging beam

304": Diffuse reflected light

304''': Mirror reflected light

305: Imaging device

306: Auxiliary light source

306a: first polarizer

306b: Second polarizer

307: Converging lens/converging lens set

307': Converging beams

401: Wafer

401': Identification

402: Wafer

402': Identification

403: Light source

404: Beam

405: Imaging device

The disclosures in this specification refer to and include the following figures: Figure 1 shows a schematic diagram of a backlight illumination system for wafer bonding alignment and detection.

Figure 2 shows a schematic diagram of a bright field illumination system used for wafer bonding alignment and detection.

FIG3A shows a schematic diagram of a wafer bonding alignment and detection system according to one embodiment of the present application.

FIG3B shows a schematic diagram of a wafer bonding alignment and detection system according to another embodiment of the present application.

FIG3C shows a schematic diagram of a wafer bonding alignment and detection system according to another embodiment of the present application.

Figures 4A and 4B show schematic diagrams of a wafer bonding alignment and detection method according to one embodiment of the present application.

As a rule, the various features illustrated in the drawings may not be drawn to scale. Therefore, the sizes of the various features may be arbitrarily enlarged or reduced for clarity. The shapes of the components illustrated in the drawings are exemplary shapes only and do not limit the actual shapes of the components. In addition, the implementation schemes illustrated in the drawings may be simplified for clarity. Therefore, the drawings may not illustrate all components of a given device or apparatus. Finally, the same reference numerals may be used throughout the specification and drawings to represent the same features.

In order to better understand the spirit of this application, the following is a further explanation of some of the embodiments of this application.

In this specification, unless otherwise specified or limited, relative terms (such as "central", "longitudinal", "lateral", "front", "rear", "right", "left", "inner", "outer", "lower", "higher", "horizontal", "vertical", "higher", "lower", "above", "below", "top", "bottom", etc.) and their derivative terms (such as "horizontally", "downwardly", "upwardly", etc.) should be interpreted as referring to the directions described in the discussion or depicted in the attached drawings. Such relative terms are used for convenience of description only and do not require that the present application be constructed or operated in a specific direction.

Various implementations of the present application are discussed in detail below. Although specific implementations are discussed, it should be understood that such implementations are for illustrative purposes only. Those skilled in the art will recognize that other components and configurations may be used without departing from the spirit and scope of protection of the present application. The implementation of the present application may not necessarily include all components or steps in the embodiments described in the specification, and the execution order of each step may be adjusted according to the actual application.

FIG1 shows a schematic diagram of a backlight illumination system for wafer bonding alignment and detection. As shown in FIG1 , the wafer bonding alignment and detection system 100 includes a first wafer 101 and a second wafer 102 to be subjected to bonding alignment or detection, wherein the first wafer 101 includes a first mark 101', and the second wafer 102 includes a second mark 102'. The first mark 101' is generally located on the upper surface of the first wafer 101, and the second mark 102' is generally located on the lower surface of the second wafer 102.

Furthermore, the wafer bonding alignment and detection system 100 includes a light source 104 located below the lower surface of the first wafer 101, and an imaging device 105 (such as a camera) located above the upper surface of the second wafer 102, wherein the light source 104 can emit a light beam 104' toward the lower surface of the first wafer 101, and the light beam sequentially illuminates the first mark 101' and the second mark 102', and finally emits from the upper surface of the second wafer 102 and reaches the imaging device 105, so as to allow the imaging device 105 to photograph the first mark 101' and the second mark 102', thereby implementing wafer bonding alignment or detection. Since the light beam 104' used for illumination is emitted from the back side of the first wafer 101, the illumination method shown in FIG. 1 can be called backlight illumination.

However, the application scenarios of backlighting are limited. For example, when the lower surface of the first wafer 101 is coated with a film layer 103 with low light transmittance (for example, at least low light transmittance within the wavelength range of the light source 104), the light beam 104' will not be able to penetrate the film layer 103, resulting in the imaging device 105 being unable to effectively form an image. Therefore, the backlighting shown in FIG. 1 cannot be used in this situation.

FIG2 shows a schematic diagram of a bright field illumination system for wafer bonding alignment and detection. As shown in FIG2 , the wafer bonding alignment and detection system 200 includes a first wafer 201 and a second wafer 202 to be subjected to bonding alignment or detection, wherein the first wafer 201 includes a first mark 201', and the second wafer 202 includes a second mark 202'. The first mark 201' is generally located on the upper surface of the first wafer 201, and the second mark 202' is generally located on the lower surface of the second wafer 202.

Different from the backlight illumination system shown in FIG. 1 , the wafer bonding alignment and detection system 200 shown in FIG. 2 does not include a backlight source, but a light source 203 is placed above the upper surface 2022 of the second wafer 202. The light beam 203' emitted from the light source 203 is reflected by the semi-reflective semi-transparent mirror 204 and then vertically incident on the upper surface 2022 of the second wafer 202.

A portion of the light incident on the upper surface 2022 of the second wafer 202 will penetrate the upper surface 2022 of the second wafer 202 and illuminate the second mark 202' and the first mark 201' and generate corresponding reflected light (not shown). The reflected light generated at the second mark 202' and the first mark 201' will be emitted from the upper surface 2022 of the second wafer 202 and further pass through the semi-reflective semi-transparent mirror 204 to reach the imaging device 205 (such as a camera), so that the imaging device 205 can take pictures of the first mark 201' and the second mark 202', thereby implementing wafer bonding alignment or detection. Another portion of the light incident on the upper surface 2022 of the second wafer 202 is directly reflected by the upper surface 2022 of the second wafer 202 to generate reflected light 203". The reflected light 203" passes through the semi-reflective and semi-transparent mirror 204 and enters the imaging device 205, which can generate a bright field of view in the imaging device 205. Therefore, the lighting method shown in FIG. 2 can be called bright field lighting. For the sake of clarity, FIG. 2 shows the reflected light 203" as being separated from the corresponding incident light by a certain distance. Those familiar with this technology should know the actual position and direction of the reflected light 203". The intensity of the reflected light generated at the upper surface 2022 of the second wafer 202 received by the imaging device 205 is much greater than the intensity of the reflected light generated at the first mark 201' and the second mark 202', which will cause the imaging device 205 to be unable to clearly image the first mark 201' and the second mark 202'.

Therefore, although the bright field illumination system shown in FIG. 2 can be applied to the alignment of wafers coated with a low-transmittance film on the back side, thereby breaking through the application scene limitation of the backlight illumination system shown in FIG. 1, it will be affected by the strong reflection of the upper surface 2022 of the second wafer 202 and cannot obtain clear imaging.

FIG3A shows a schematic diagram of a wafer bonding alignment and detection system according to one embodiment of the present application. As shown in FIG3A , the wafer bonding alignment and detection system 300 includes a first wafer 301 and a second wafer 302 to be subjected to bonding alignment or detection, wherein the first wafer 301 includes a first identification 301', and the second wafer 302 includes a second identification 302'. The first identification 301' is generally located on the upper surface of the first wafer 301, and the second identification 302' is generally located on the lower surface of the second wafer 302. Further, the wafer bonding alignment and detection system 300 includes a light source 303, which is located above the upper surface 3022 of the second wafer 302. The light source 303 is configured to emit a light beam 303' obliquely toward the second mark 302' on the second wafer 302. It should be understood that the oblique emission of the light beam 303' means that the angle between the light beam 303' and the upper surface 3022 of the second wafer 302 is not equal to 90 degrees.

In one embodiment, the obliquely emitted light beam 303' may be converged by a converging lens or a converging lens set 304, thereby generating a converging light beam 304', which may be substantially focused on the second mark 302'. However, it should be understood that the obliquely emitted light beam 303' may also be directly emitted to the second mark 302' without being converged by a converging lens or a converging lens set 304. In some embodiments, the light source 104 may be an infrared light source or any suitable light source for illumination.

Still referring to FIG. 3A , a portion of the convergent light beam 304' obliquely incident on the second mark 302' will penetrate the upper surface 3022 of the second wafer 302 and illuminate the second mark 302'. The second mark 302' has a scattering effect on light, thereby generating diffuse reflection light here (as shown by the dotted line in FIG. 3A ). Part of the diffuse reflection light 304" of this diffuse reflection light can penetrate the upper surface 3022 of the second wafer 302 to reach the imaging device 305 (e.g., a camera). Another portion of the convergent light beam 304' is obliquely reflected outward by the flat and smooth upper surface 3022 of the second wafer 302 to form mirror reflection light 304'". The imaging device 305 is generally aligned with the second mark 30 2', and the direction of light received is inconsistent with the propagation direction of the mirror-reflected light 304'''. For example, the direction of light received by the imaging device 305 can be substantially perpendicular to the upper surface 3022 of the second wafer 302. Although the light intensity of the mirror-reflected light 304''' is much greater than the light intensity of the diffusely reflected light 304" generated from the second mark 302', most or even all of it will not reach the imaging device 305 due to its oblique outward reflection, so it will not have an adverse effect on the clear imaging of the second mark 302'.

It should be understood that the position and/or orientation of the light source 303 and/or the converging lens or the converging lens group 304 can also be adjusted so that the obliquely emitted light beam 303' is obliquely emitted toward the first mark 301' on the first wafer 301 to generate diffusely reflected light, so that the imaging device 305 can shoot the first mark 301'. The imaging device 305 is generally aligned with the first mark 301'. Since the light beam 303' is obliquely emitted toward the first mark 301', most or even all of the mirror-reflected light formed by the light beam 303' being obliquely reflected outward by the upper surface 3022 of the second wafer 302 will not reach the imaging device 305, and thus will not have an adverse effect on the clear imaging of the first mark 301'.

FIG3B shows a schematic diagram of a wafer bonding alignment and detection system according to another embodiment of the present application. The wafer bonding alignment and detection system 300 shown in FIG3B is substantially similar to FIG3A, wherein the same components are represented by the same reference numerals. Compared with FIG3A, the wafer bonding alignment and detection system 300 shown in FIG3B further includes a first polarizer 306a and a second polarizer 306b.

The first polarizer 306a (also called a polarizer) may be located at the output of the light source 303 or the converging lens or the converging lens group 304, and may be configured so that the light beam 304' incident on the upper surface 3022 of the second wafer 302 is linearly polarized light. A portion of the light beam 304' is obliquely reflected outward by the upper surface 3022 of the second wafer 302 to form a mirror-reflected light 304''', which is still linearly polarized light. The second polarizer 306b (also called an analyzer) may be located between the second wafer 302 and the imaging device 305, and may be configured to at least partially block the mirror-reflected light 304''' (for example, by making the polarization direction of the second polarizer 306b perpendicular to the polarization direction of the mirror-reflected light 304''', the mirror-reflected light 304''' may be almost completely blocked; by making the polarization direction of the second polarizer 306b and the polarization direction of the mirror-reflected light 304''' form an angle greater than 0 degrees and less than 90 degrees, the mirror-reflected light 304''' may be partially blocked), thereby further reducing the mirror-reflected light 304''' entering the imaging device 305.

On the other hand, another part of the light beam 304' penetrates the upper surface 3022 of the second wafer 302 and irradiates the second mark 302' of the second wafer 302 (or the first mark 301' of the first wafer 301), and generates diffuse reflection light. The polarization characteristics of diffuse reflection light are similar to natural light, and can have polarization components in various directions. Therefore, the polarization component in the diffuse reflection light whose polarization direction is consistent with the polarization direction of the second polarizer 306b can pass through the second polarizer 306b to reach the imaging device 305 (such as the diffuse reflection light 304" shown in Figure 3B).

In this way, the wafer bonding alignment and detection system 300 shown in FIG. 3B can obtain a clearer imaging effect.

FIG3C shows a schematic diagram of a wafer bonding alignment and detection system according to another embodiment of the present application. The wafer bonding alignment and detection system 300 shown in FIG3C is substantially similar to FIG3A, wherein the same components are represented by the same reference numerals. Compared with FIG3A, the wafer bonding alignment and detection system 300 shown in FIG3C further includes an auxiliary light source 306 and an auxiliary converging lens or converging lens group 307 located above the upper surface 3022 of the second wafer 302. The auxiliary light source 306 and the auxiliary converging lens or converging lens group 307 can be placed on both sides of the imaging device 305 substantially symmetrically with the light source 303 and the converging lens or converging lens group 304.

Similar to the light source 303, the auxiliary light source 306 can be configured to obliquely emit a light beam toward the second mark 302' of the second wafer 302 (or the first mark 301' of the first wafer 301), and the light beam can be converged by the auxiliary converging lens or converging lens group 307 to generate a converging light beam 307', and the converging light beam 307' can be roughly focused on the second mark 302' of the second wafer 302 (or the first mark 301' of the first wafer 301). It should be understood that the light beam obliquely emitted by the auxiliary light source 306 can also be directly emitted to the second mark 302' (or the first mark 301') without being converged by the auxiliary converging lens or converging lens group 307.

It should still be understood that the light source 303 and the auxiliary light source 306 are not limited to being symmetrically distributed on both sides of the imaging device 305 as shown in FIG. 3C , but can be flexibly placed at any appropriate position, as long as it is ensured that the outgoing light beams of the light source 303 and the auxiliary light source 306 can be obliquely projected toward the second mark 302' (or the first mark 301') from different positions. Moreover, the number of light sources is not limited to the two shown in FIG. 3C , but can be any number. As an embodiment, a plurality of light sources can be arranged in a ring shape relative to the imaging device 305 to further increase the intensity of diffusely reflected light incident on the imaging device 305. In some embodiments, a corresponding converging lens or converging lens group can be provided for each light source. According to some embodiments of this application, the polarizer and analyzer shown in FIG. 3B can also be applied to an example with multiple light sources, for example, a corresponding polarizer can be set for each light source.

Figures 4A and 4B show schematic diagrams of a wafer bonding alignment and detection method according to an embodiment of the present application. The method can be implemented using the wafer bonding alignment and detection system shown in Figure 3A.

Referring to FIG. 4A , first, a wafer 402 is provided, which has a mark 402 ′ located on the lower surface of the wafer 402 .

Secondly, a light source 403 is provided above the upper surface of the wafer 402 to generate a light beam 404 that is obliquely directed toward the mark 402'. In some embodiments, a converging lens or a converging lens group may be further provided to converge the light beam 404 and direct it toward the mark 402'. In some embodiments, the converging light beam 404 may be substantially focused on the mark 402'.

Then, an imaging device 405 (such as a camera) is provided above the upper surface of the wafer 402 to receive diffuse reflection light generated at the marker 402', thereby photographing the marker 402'. Since the light beam 404 is directed toward the marker 402' in an inclined manner, the imaging device 405 is allowed to receive only diffuse reflection light from the marker 402', and not receive mirror reflection light generated from the upper surface of the wafer 402. As an embodiment, after photographing the marker 402', the image acquisition positioning information (such as (but not limited to) coordinates) of the marker 402' can be further obtained for subsequent alignment operations.

Further referring to FIG. 4B , a wafer 401 having a mark 401 'is provided below the wafer 402, wherein the mark 401 'is located at the upper surface of the wafer 401, and the upper surface of the wafer 401 is arranged opposite to the lower surface of the wafer 402. Although the wafer 401 is not shown in FIG. 4A , it should be understood that the wafer 401 may have been provided below the wafer 402 before the wafer 402 is photographed.

Next, the angle of the light source 403 is adjusted so that the light beam 404 is obliquely incident on the mark 401'. In some embodiments, the converging lens or converging lens group used to converge the light beam 404 can be further adjusted so that the light beam 404 is generally focused on the mark 401'. In some embodiments, it may not be necessary to adjust the angle of the light source 403 or adjust the converging lens or converging lens group.

Then, the imaging device 405 receives the diffuse reflected light generated at the marker 401' to photograph the marker 401'. As an embodiment, after photographing the marker 401', the image of the marker 401' can be further obtained to collect positioning information for subsequent alignment operations. In some embodiments, the marker 401' can be photographed first, and then the marker 402' can be photographed.

Subsequently, the photographed identification 402' is compared with the identification 401' (for example, the image acquisition positioning information of the identification 402' is compared with the image acquisition positioning information of the identification 401'), and the relative position of the wafer 402 and the wafer 401 is adjusted based on the comparison result, so that the identification 402' and the identification 401' are aligned with each other, and then the wafer 401 and the wafer 402 are bonded.

It should be understood that the above-mentioned wafer bonding alignment process is not limited to a single operation, but the relative position of the mark can be continuously adjusted by repeatedly performing the above-mentioned operation to finally achieve wafer alignment.

After wafer bonding is completed, the wafer bonding quality can also be detected by similar methods.

First, wafer 401 and wafer 402 that have been bonded are provided, wherein wafer 401 is below wafer 402, the lower surface of wafer 402 has a mark 402', and the upper surface of wafer 401 has a mark 401'. Next, a light source 403 is provided above the upper surface of wafer 402 to generate a light beam 404 that is obliquely incident on marks 401' and 402'. In some embodiments, a converging lens or a converging lens set may be further provided to converge light beam 404 and project it toward marks 401' and 402'. In some embodiments, the converging light beam 404 may be substantially focused on marks 401' and 402'. Then, an imaging device 405 (e.g., a camera) is provided above the upper surface of the wafer 402 to receive diffusely reflected light generated at the markers 401' and 402', thereby simultaneously photographing the markers 401' and 402'. As an embodiment, after photographing the markers 401' and 402', image acquisition positioning information (e.g., but not limited to, coordinates) of the markers 401' and 402' may be further obtained. Subsequently, the photographed identification 402' is compared with the identification 401' (for example, the image acquisition positioning information of the obtained identification 402' is compared with the image acquisition positioning information of the identification 401'), and the offset of the bonding alignment between the wafer 402 and the wafer 401 is calculated based on the comparison result.

It should be understood that the wafer bonding alignment and detection method shown in FIGS. 4A and 4B can also be implemented by using the wafer bonding alignment and detection system shown in FIG. 3B or FIG. 3C to further improve the imaging effect and promote the alignment and detection operation of wafer bonding. For example, the method may further include providing a first polarizer and a second polarizer, wherein the first polarizer is configured to make the light beam 404 incident on the upper surface of the second wafer 402 linearly polarized, and the second polarizer is configured to at least partially block the specular reflection light generated by the light beam 404 on the upper surface of the second wafer 402 from entering the imaging device 405. For another example, the method may further include providing one or more auxiliary light sources to generate one or more corresponding auxiliary light beams, each of which is inclined toward the mark 401' and/or the mark 402'. In addition, after the wafer bonding is completed in each embodiment shown in Figures 3A to 4B, the gap between the upper and lower wafers will no longer exist, and the two wafers will be combined into a whole.

The wafer bonding alignment and detection device and method provided in each embodiment of the present application allows the imaging device to receive only diffusely reflected light generated from the wafer mark, and not receive the obliquely reflected mirror light generated by the wafer surface. Therefore, the wafer bonding alignment and detection device and method provided in each embodiment of the present application can effectively eliminate the interference of mirror reflected light on wafer mark imaging, increase the signal-to-noise ratio and clarity of imaging, and thus obtain better wafer bonding alignment and detection accuracy. In addition, the wafer bonding alignment and detection device and method provided in each embodiment of this application can still be used normally when a low-transmittance film layer is coated on the back side of the wafer, and the application scenarios are not limited.

The technical content and technical features of this application have been described by the above-mentioned relevant embodiments, but the above-mentioned embodiments are only examples for implementing this application. Those familiar with this technology can still make various substitutions and modifications based on the teachings and disclosures of this application without departing from the spirit of this application. Therefore, the embodiments disclosed in this application do not limit the scope of this application. On the contrary, modifications and equivalent settings included in the spirit and scope of the patent application are included in the scope of this application.

300:System

301: First wafer

301': First identification

302: Second wafer

302': Second identification

3022: Upper surface

303: Light source

303': Beam

304: Converging lens or/and converging lens group

304': Converging beam

304": Diffuse reflected light

304''': Mirror reflected light

305: Imaging device

Claims (19)

A device for wafer bonding alignment and detection, comprising: a light source configured to generate a light beam, the light beam obliquely incident on a mark on a first wafer surface; an imaging device configured to photograph the mark by receiving at least a portion of diffuse reflection light generated by the light beam at the mark; and a first polarizer and a second polarizer, wherein the light beam passes through a second wafer surface and then incident on the mark, the first polarizer is configured to make the light beam incident on the second wafer surface linearly polarized light, and the second polarizer is configured to at least partially block the specular reflection light generated by the light beam on the second wafer surface from entering the imaging device. As in the device of claim 1, wherein the light source is an infrared light source. The device of claim 1 further comprises a converging lens or a converging lens set, wherein the converging lens or the converging lens set is configured to converge the light beam emitted from the light source. A device as claimed in claim 3, wherein the converged light beam is substantially focused on the mark. As in claim 1, the polarization direction of the second polarizer is perpendicular to the polarization direction of the mirror-reflected light. The device of claim 1 further comprises one or more auxiliary light sources, wherein the one or more auxiliary light sources are configured to generate one or more corresponding auxiliary light beams, each of the one or more auxiliary light beams being inclined toward the above-mentioned mark. As in claim 6, the one or more auxiliary light sources and the light source are arranged in a ring shape relative to the imaging device. A method for wafer bonding alignment and detection, comprising: providing a wafer having a mark on a first wafer surface; providing a light source configured to generate a light beam, the light beam being inclined toward the mark; providing an imaging device configured to photograph the mark by receiving at least a portion of diffuse reflection light generated by the light beam at the mark; and providing a first polarizer and a second polarizer, wherein the light beam passes through a second wafer surface and then is directed toward the mark, the first polarizer being configured to make the light beam incident on the second wafer surface linearly polarized light, and the second polarizer being configured to at least partially block the specular reflection light generated by the light beam on the second wafer surface from entering the imaging device. The method of claim 8 further includes collecting the positioning information of the image of the above-mentioned mark after photographing the above-mentioned mark. As in the method of claim 8, wherein the wafer is a first wafer, the mark is a first mark, and the light beam is a first light beam, the method further comprises: providing a second wafer having a second mark on a second wafer surface, wherein the second wafer surface is arranged opposite to the first wafer surface; generating a second light beam obliquely incident on the second mark by the light source; and receiving at least a portion of the diffusely reflected light generated by the second light beam at the second mark by the imaging device to photograph the second mark. The method of claim 10 further includes: comparing the photographed first identification with the second identification; and adjusting the relative position of the first wafer and the second wafer based on the comparison result so that the first identification and the second identification are aligned with each other. As in the method of claim 8, the wafers are the first wafer and the second wafer that have been bonded, the surface of the first wafer is the bonding surface between the first wafer and the second wafer, and the identification includes the first identification of the first wafer and the second identification of the second wafer. The method of claim 12 further includes: comparing the photographed first identification with the second identification; and calculating the offset of the bonding alignment between the first wafer and the second wafer based on the comparison result. As in the method of claim 8, wherein the light source is an infrared light source. The method of claim 8 further comprises providing a converging lens or a converging lens set so that the light beam is converged and directed toward the mark. A method as claimed in claim 15, wherein the converged light beam is substantially focused on the mark. As in the method of claim 8, the polarization direction of the second polarizer is perpendicular to the polarization direction of the mirror-reflected light. The method of claim 8 further comprises providing one or more auxiliary light sources to generate corresponding one or more auxiliary light beams, each of the one or more auxiliary light beams being inclined toward the above-mentioned mark. As in the method of claim 18, the one or more auxiliary light sources and the light source are arranged in a ring shape relative to the imaging device.