Wafer alignment device and wafer bonding method

Abstract

The invention discloses a wafer alignment device and a bonding method. The wafer alignment device comprises: an infrared light source for providing an infrared beam for aligning a first wafer and a second wafer; the confocal optical system is located on one side of the first wafer and used for transmitting the infrared light beams to the second surface of the first wafer and the first surface, opposite to the first surface, of the second wafer through the first wafer so as to obtain positioning of a first identifier on the second surface and positioning of a second identifier on the first surface respectively; and the movement mechanism is respectively connected with the first wafer and the second wafer, and moves the position of the first wafer and / or the second wafer based on the positioning of the first identifier and the second identifier, so that the first identifier and the second identifier are vertically aligned by means of an infrared beam. According to the invention, alignment errors caused by optical axis deviation of the two sets of optical systems and movement errors caused by avoidance of the movement platform in order to obtain the wafer identifier on the other side can be avoided, so that the alignment precision is improved, and the wafer bonding precision is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processes, and in particular to a wafer alignment device, a wafer bonding method, and a computer-readable storage medium. Background Art

[0002] Wafer bonding technology refers to a technology that combines two wafers with clean surfaces into a whole through external force. Among them, the alignment accuracy of the wafers is a key parameter in wafer bonding technology. Usually, during the wafer bonding process, the upper and lower visible light optical systems can be used to identify and locate the marks on the two wafers respectively, and then the two wafers can be aligned.

[0003] In the prior art, such as Figure 1 As shown, the two wafers used for bonding correspond to a set of optical systems respectively, that is, an optical system 103 is provided on one side of the lower wafer 101, and an optical system 104 is provided on one side of the upper wafer 102. In step S110, the lower wafer 101 is positioned by the optical system 103. Then, step S120 is executed to position the upper wafer 102 by the optical system 104. Then, step S130 is executed to perform alignment calibration through the positioning data of the lower wafer 101 and the upper wafer 102 obtained by the two sets of optical systems 103 and 104. Finally, step S140 is executed to bond the lower wafer 101 and the upper wafer 102.

[0004] However, since two sets of optical systems are currently required to align and bond the upper and lower wafers, there is a deviation between the optical axes of the upper and lower optical systems, and this deviation will change with the movement of each optical system, so it cannot be fully compensated. Figure 1 In the process, the visible light of the traditional alignment beam cannot penetrate the upper wafer 102 to image the mark of the lower wafer 101. Therefore, if only one set of optical systems is used to collect the mark images of the upper and lower wafers, the motion platform needs to be moved back and forth to avoid it so that the visible light can illuminate the other wafer and image its mark. The avoidance action of the motion platform will cause movement errors. These deviations will ultimately affect the alignment accuracy of the wafer. Whether it is the alignment error caused by the optical axis deviation of the two sets of optical systems or the movement error caused by the avoidance of the motion platform, it will cause the alignment accuracy of the wafer to decrease, thereby affecting the bonding accuracy of the wafer.

[0005] In order to solve the above-mentioned problems existing in the prior art, the art is in urgent need of a wafer alignment technology that can avoid the alignment error caused by the optical axis deviation of the two optical systems corresponding to the two wafers, and the movement error caused by the motion platform avoiding to obtain the wafer mark on the other side, thereby improving the positioning accuracy and further improving the accuracy of wafer bonding. Summary of the invention

[0006] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or decisive elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides a wafer alignment device, a wafer bonding method, and a computer-readable storage medium, which can avoid the alignment error caused by the optical axis deviation of the two optical systems corresponding to the two wafers, and the movement error caused by the motion platform avoiding to obtain the wafer mark on the other side, thereby improving the positioning accuracy and further improving the wafer bonding accuracy.

[0008] Specifically, the wafer alignment device provided according to the first aspect of the present invention includes: an infrared light source, providing an infrared light beam for aligning a first wafer and a second wafer; a confocal optical system, located on one side of the first wafer, for transmitting the infrared light beam through the first wafer to the second surface of the first wafer, and the first surface of the second wafer opposite thereto, so as to respectively obtain the positioning of a first mark on the second surface and a second mark on the first surface; and a motion mechanism, respectively connected to the first wafer and the second wafer, and based on the positioning of the first mark and the second mark, moving the position of the first wafer and / or the second wafer, so as to vertically align the first mark and the second mark with the help of the infrared light beam.

[0009] Furthermore, in some embodiments of the present invention, the infrared light source is an adjustable light source for switching infrared light beams of different wavelengths according to the type of thin film prepared on the surface of the wafer.

[0010] Furthermore, in some embodiments of the present invention, the second surface of the first wafer includes at least two of the first markings, and the first surface of the second wafer includes at least two of the second markings, and the at least two first markings and the at least two second markings are used to determine the moving deflection angle of the first wafer and / or the second wafer.

[0011] Furthermore, in some embodiments of the present invention, the wafer alignment device includes: at least two groups of the confocal optical systems and their corresponding infrared light sources, and the at least two groups of the confocal optical systems and their corresponding infrared light sources are distributed on the same side of the first wafer, and are used to image the first mark on the second surface of the first wafer and the second mark on the first surface of the second wafer.

[0012] Furthermore, in some embodiments of the present invention, at least two groups of the confocal optical systems and their corresponding infrared light sources are symmetrical about the center of the first wafer, and the at least two first marks on the first wafer are used as alignment references.

[0013] Furthermore, in some embodiments of the present invention, the confocal optical system includes a first aperture, a second aperture, and an image collector, wherein the first aperture and the second aperture are located on conjugate planes of the focal planes of the first wafer and the second wafer, wherein the first aperture is located in front of the image collector, and the second aperture is located in front of the infrared light source, and the infrared light beam emitted by the infrared light source passes through the second aperture to become a point light source, and is respectively focused on a first mark on the focal plane of the first wafer and a second mark on the focal plane of the second wafer, and the image collector only receives images of the first mark and the second mark formed by the light focused by the first aperture.

[0014] Furthermore, in some embodiments of the present invention, the confocal optical system includes a beam splitter located at the intersection of the optical axis of the infrared light source and the optical axis of the image display, so as to reflect the infrared light beam emitted by the infrared light source to the focal planes of the first wafer and the second wafer respectively, and the reflected light from the focal planes of the first wafer and the second wafer then passes through the beam splitter and reaches the image display to perform identification imaging of the first logo and the second logo.

[0015] Furthermore, in some embodiments of the present invention, the confocal optical system includes a second aperture and a collimating lens, wherein the second aperture is located between the infrared light source and the beam splitter, and the first lens is located between the second aperture and the beam splitter, and is used to filter the light source on the non-focused surface.

[0016] Furthermore, in some embodiments of the present invention, the motion mechanism includes a lateral moving part and a longitudinal moving part, and the lateral moving part is used to make the first wafer and / or the second wafer move laterally for identification search, and the longitudinal moving part is used to make the first wafer and / or the second wafer move longitudinally for identification focusing.

[0017] Furthermore, in some embodiments of the present invention, the longitudinal moving part also includes a rotation axis for rotating the first wafer and / or the second wafer at an angle to perform marking focusing.

[0018] In addition, the above-mentioned wafer bonding method provided according to the second aspect of the present invention includes the following steps: obtaining a first wafer; positioning the first mark on the second surface of the first wafer through the above-mentioned wafer alignment device provided by the first aspect of the present invention; obtaining a second wafer; obtaining the second mark on the first surface of the second wafer through the wafer alignment device for positioning; adjusting the relative positions of the first wafer and the second wafer based on the position difference between the first mark and the second mark; and in response to the vertical alignment of the first mark and the second mark, pressing the first wafer and the second wafer to complete wafer bonding.

[0019] In addition, according to the third aspect of the present invention, there is also provided a computer-readable storage medium on which computer instructions are stored. When the computer instructions are executed by a processor, the above-mentioned wafer bonding method provided by the second aspect of the present invention is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0021] Figure 1 It is a flow chart of a conventional wafer bonding process in the prior art;

[0022] Figure 2 A schematic structural diagram of a wafer alignment device provided according to some embodiments of the present invention is shown;

[0023] Figure 3 A schematic structural diagram of aligning a wafer with a wafer alignment device provided in some embodiments of the present invention is shown;

[0024] Figure 4 A schematic diagram showing a structure of a first identifier and a second identifier provided according to some embodiments of the present invention is shown;

[0025] Figure 5 A flowchart of a wafer bonding method provided according to some embodiments of the present invention is shown; and

[0026] Figure 6 A flow chart of a wafer bonding process provided according to some embodiments of the present invention is shown.

[0027] Reference numerals:

[0028] Steps S110 to S140;

[0029] 101 lower wafer;

[0030] 102 wafer loading;

[0031] 103, 104 optical system;

[0032] 200 Wafer alignment device;

[0033] 210 infrared light source;

[0034] 220 Confocal optical system;

[0035] 221 Spectroscope;

[0036] 222 first aperture;

[0037] 223 Image collector;

[0038] 224 Second aperture;

[0039] 225 Collimating lens;

[0040] 226 first lens;

[0041] 227 Second lens;

[0042] 310 First Wafer;

[0043] 311, 321 first surface;

[0044] 312 second surface;

[0045] 320 second wafer;

[0046] 330 First Identification;

[0047] 340 Second identification; and

[0048] Steps S410 to S460. DETAILED DESCRIPTION

[0049] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In addition, the terms "upper", "lower", "left", "right", "top", "bottom", "horizontal" and "vertical" used in the following description should be understood as the directions shown in the paragraph and the related drawings. Such relative terms are only used for the convenience of description and do not mean that the device described therein must be manufactured or operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0052] It is understood that although the terms "first", "second", "third", etc. may be used herein to describe various components, regions, layers and / or parts, these components, regions, layers and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers and / or parts. Therefore, the first component, region, layer and / or part discussed below may be referred to as a second component, region, layer and / or part without departing from some embodiments of the present invention.

[0053] As mentioned above, in the prior art, Figure 1 As shown, the two wafers used for bonding correspond to a set of optical systems respectively, that is, an optical system 103 is provided on one side of the lower wafer 101, and an optical system 104 is provided on one side of the upper wafer 102. In step S110, the lower wafer 101 is positioned by the optical system 103. Then, step S120 is executed to position the upper wafer 102 by the optical system 104. Then, step S130 is executed to perform alignment calibration through the positioning data of the lower wafer 101 and the upper wafer 102 obtained by the two sets of optical systems 103 and 104. Finally, step S140 is executed to bond the lower wafer 101 and the upper wafer 102.

[0054] However, since two sets of optical systems are currently required to align and bond the upper and lower wafers, there is a deviation between the optical axes of the upper and lower optical systems, and this deviation will change with the movement of each optical system, so it cannot be fully compensated. Figure 1In the process, the visible light of the traditional alignment beam cannot penetrate the upper wafer 102 to image the mark of the lower wafer 101. Therefore, if only one set of optical systems is used to collect the mark images of the upper and lower wafers, the motion platform needs to be moved back and forth to avoid it so that the visible light can illuminate the other wafer and image its mark. The avoidance action of the motion platform will cause movement errors. These deviations will ultimately affect the alignment accuracy of the wafer. Whether it is the alignment error caused by the optical axis deviation of the two sets of optical systems or the movement error caused by the avoidance of the motion platform, it will cause the alignment accuracy of the wafer to decrease, thereby affecting the bonding accuracy of the wafer.

[0055] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a wafer alignment device, a wafer bonding method, and a computer-readable storage medium, which can avoid the alignment error caused by the optical axis deviation of the two optical systems corresponding to the two wafers, and the movement error caused by the motion platform avoiding to obtain the wafer mark on the other side, thereby improving the positioning accuracy and further improving the wafer bonding accuracy.

[0056] In some non-limiting embodiments, the wafer alignment device provided by the first aspect of the present invention may be used to implement the wafer bonding method provided by the second aspect of the present invention.

[0057] Specifically, in some non-limiting embodiments, the computer-readable storage medium provided in the third aspect of the present invention stores computer instructions, which, when executed by a processor, can be used to implement the wafer bonding method provided in the second aspect of the present invention.

[0058] The working principle of the above-mentioned wafer alignment device will be described below in conjunction with some embodiments of the wafer bonding method. Those skilled in the art will understand that these embodiments of the wafer bonding method are only some non-limiting implementation methods provided by the present invention, which are intended to clearly demonstrate the main concept of the present invention and provide some specific solutions that are convenient for the public to implement, rather than to limit all working modes or all functions of the wafer alignment device. Similarly, the wafer alignment device is also only a non-limiting implementation method provided by the present invention, and does not constitute a limitation on the implementation subject of each step in these wafer bonding methods.

[0059] Please see Figure 2 , Figure 2 A schematic structural diagram of a wafer alignment device provided according to some embodiments of the present invention is shown.

[0060] like Figure 2As shown, in some embodiments of the present invention, the wafer alignment device 200 may mainly include an infrared light source 210, a confocal optical system 220, and a motion mechanism (not shown in the drawings). The infrared light source 210 may provide an infrared light beam that can penetrate the first wafer 310 and is used to align the first wafer 310 and the second wafer 320. The confocal optical system 220 may be located at the first wafer 310 (e.g. Figure 2 The motion mechanism is configured to transmit an infrared light beam through the first wafer 310 to the second surface of the first wafer 310 and the first surface of the second wafer 320 opposite thereto, so as to respectively obtain the positioning of the first mark on the second surface and the second mark on the first surface. The motion mechanism can be connected to the first wafer 310 and the second wafer 320 respectively, and based on the positioning of the first mark and the second mark, the position of the first wafer 310 and / or the second wafer 320 is moved to vertically align the first mark and the second mark with the help of the infrared light beam.

[0061] Specifically, the infrared light source 210 can be optionally used as an illumination light source, and an adjustable light source can be selected, so that infrared light beams of different bands can be switched according to the different types of thin films prepared on the surfaces of different product wafers to achieve the best lighting environment, thereby improving image quality and further improving alignment accuracy. In the actual semiconductor process, the thin films prepared on the surfaces of different product wafers are different, which will have different effects on the reflection of the infrared light beam. Therefore, if the same fixed light source is used, the best lighting environment cannot be obtained, which will affect the alignment accuracy of different product wafers.

[0062] Furthermore, since high-purity silicon can accurately control the amount of doping elements, the impact of impurities in the raw materials can be reduced, thereby improving the performance and reliability of the final product. Existing semiconductor equipment is mainly designed around silicon devices. In this embodiment, the first wafer 310 and / or the second wafer 320 can be made of high-purity silicon wafers to facilitate subsequent processing and preparation. However, traditional visible light cannot penetrate silicon wafers, even ultraviolet light cannot penetrate, therefore, in this embodiment, the infrared light source 210 can provide infrared light that can penetrate high-purity silicon wafers to perform identification alignment of the upper and lower wafers.

[0063] Please further combine Figure 3 Common understanding, Figure 3 A schematic diagram of the structure of a wafer alignment device aligning a wafer according to some embodiments of the present invention is shown. Figure 3As shown, when the infrared light source 210 uses a near-infrared light source, this wavelength band can be imaged through the silicon wafer. The infrared light beam emitted by the infrared light source 210 can pass through the first surface 311 of the first wafer 310 and be transmitted to the second surface 312 of the first wafer 310 and the first surface 321 of the second wafer 320 opposite thereto, so as to image the first mark 330 on the second surface 312 of the first wafer 310 and the second mark 340 on the first surface 321 of the second wafer 320 through the confocal optical system 220, thereby avoiding Figure 1 In the prior art shown in , a moving platform is required to avoid the mechanical error caused by the alignment beam. At the same time, before the wafers are bonded, the upper and lower wafers can also be identified and aligned with the alignment marks in real time.

[0064] Continue as Figure 3 As shown, in some embodiments of the present invention, the second surface 312 of the first wafer 310 may include a first mark 330, and the first surface 321 of the second wafer 320 may include a second mark 340. For example, the first mark 330 may be located at the center of the second surface 312 of the first wafer 310, and the second mark 340 may also be located at the center of the first surface 321 of the second wafer 320. The positions of the first wafer 310 and the second wafer 320 are adjusted by a motion mechanism so that the first mark 330 at the center of the first wafer 310 and the second mark 340 at the center of the second wafer 320 are aligned up and down, thereby achieving alignment of the first wafer 310 and the second wafer 320.

[0065] Further, in some preferred embodiments, the second surface 312 of the first wafer 310 may include at least two first marks 330, and the first surface 321 of the second wafer 320 may also include corresponding at least two second marks 340. Through the at least two first marks 330 on the first wafer 310 and the at least two second marks 340 on the second wafer 320, the movement deflection angle required to adjust the first wafer 310 and / or the second wafer 320 can be calculated during the wafer position adjustment process. For the convenience of calculation, preferably, the at least two first marks 330 in this embodiment can be symmetrical about the center of the first wafer 310, and similarly, the at least two second marks 340 can also be symmetrical about the center of the second wafer 320.

[0066] In this regard, the wafer alignment device 200 may include at least two sets of confocal optical systems 220 and their corresponding infrared light sources 210 ( Figure 3The at least two sets of confocal optical systems 220 and their corresponding infrared light sources 210 can be distributed on the same side of the first wafer 310 (or the second wafer 320). In this embodiment, multiple confocal optical systems 220 on one side are used to image the upper and lower wafers, which can reduce the number of confocal optical systems 220 and the number of second confocal optical systems 210. Figure 1 The alignment error caused by the optical axis deviation of the upper and lower optical systems used in the prior art shown in FIG.

[0067] Optionally, corresponding to the positions of the at least two first marks 330 and the at least two second marks 340 on the respective wafers in the above preferred embodiment, the at least two groups of confocal optical systems 220 and their corresponding infrared light sources 210 can be further symmetrical about the center of the first wafer 310, and the at least two first marks 330 on the first wafer 310 are used as alignment references, so as to adjust the position of the second wafer 320 so that the at least two second marks 340 on the second wafer 320 are aligned with the first marks 330. In some other embodiments, the at least two second marks 340 on the second wafer 320 can also be used as alignment references to adjust the position of the first wafer 310, or the positions of the first wafer 310 and the second wafer 320 can be adjusted together, as long as the first marks 330 on the first wafer 310 are vertically aligned one by one with the second marks 340 on the second wafer 320.

[0068] Please see Figure 4 , Figure 4 A structural schematic diagram representing a first identifier and a second identifier provided according to some embodiments of the present invention is shown.

[0069] The logo may include a variety of different types of features. Figure 4 As shown, the first mark 330 and the second mark 340 can be nested topographic patterns, which are easy to be acquired by the confocal optical system 220, and can also improve the alignment accuracy of the upper and lower wafers. For example, the distance between each edge of the second mark 340 and each edge of the corresponding first mark 330 can be used to determine whether the first mark 330 and the second mark 340 are aligned. Furthermore, the nested topographic patterns can also include bar patterns, ring patterns, etc.

[0070] Please continue to return Figure 2 For a conventional optical microscope, the reflected light from the deviated focus part will interfere and overlap with the focus imaging part, thus reducing the image contrast. In the invention, Figure 2The confocal optical system 220 shown can solve this problem well. In the preferred embodiment of the present invention, for the infrared light source 210, the confocal optical system 220 can specifically be an infrared light confocal microscope.

[0071] Specifically, combined Figure 2 and Figure 3 It is commonly understood that the confocal optical system 220 mainly includes a first aperture 222, a second aperture 224, and an image collector 223. The first aperture 222 and the second aperture 24 can be located at the conjugate plane of the focal plane of the first wafer 310 and the second wafer 320 (the object to be measured), wherein the first aperture 222 can be located in front of the image collector 223, and the second aperture 224 can be located in front of the infrared light source 210. Furthermore, a collimating lens 225 can be arranged in front of the second aperture 224, and the light source of the non-focusing surface can be filtered by the second aperture 224 and the collimating lens 225. The infrared light source 210, the second aperture 224 and the collimating lens 225 can be connected and fixed by a mechanical structure.

[0072] The working principle of the confocal optical system 220 is that the infrared light beam emitted by the infrared light source 210 can pass through the second aperture 224 to become a point light source, and be focused on the first mark 330 on the focal plane of the first wafer 310 and the second mark 340 on the focal plane of the second wafer 320, respectively, and the image collector 223 can only receive the images of the first mark 330 and the second mark 340 formed by the light focused by the first aperture 222.

[0073] like Figure 2 As shown, in this embodiment, when the first wafer 310 and the second wafer 320 (the object to be measured) are in the focal plane, the light intensity collected by the image collector 223 is the largest, and when the first wafer 310 and the second wafer 320 (the object to be measured) are in the defocused plane, the light spot of the image collector 223 is diffused and the light intensity decreases rapidly. Therefore, only the points located on the focal plane of the first wafer 310 and the focal plane of the second wafer 320, that is, the light emitted by the first mark 330 located on the focal plane of the first wafer 310 and the second mark 340 located on the focal plane of the second wafer 320 can pass through the second aperture 224, while the light emitted by the points located outside the focal plane of the first wafer 310 and the second wafer 320 is defocused in the plane of the second aperture 224 and cannot pass through the first aperture 222. Therefore, the first mark 330 and the second mark 340 on the focal plane are target observation points and are bright, while other non-target observation points are dark as the background, thereby increasing the contrast and forming a clearer pattern.

[0074] Combination Figure 3It is commonly understood that, compared with the prior art, the reflected light from other surfaces of the first wafer 310 (such as the first surface 311) will interfere with the contrast of the final identification imaging of the image collector 223. The confocal optical system 220 used in the present invention can almost completely remove the focus of the first wafer 310 and the second wafer 320, that is, the scattered light other than the first mark 330 and the second mark 340, so that an image with very high contrast can be obtained, thereby greatly reducing the reflected light from other surfaces of the first wafer 310 (such as the first surface 311) entering the image collector 223, improving the clarity of the identification imaging, and further improving the alignment accuracy of the wafer bonding.

[0075] Furthermore, the confocal optical system 220 may also include a beam splitter 221. The beam splitter 221 may be located at the intersection of the optical axis of the infrared light source 210 and the optical axis of the image collector 223, and is used to reflect the horizontal infrared light beam emitted by the infrared light source 210 through the second aperture 224 and the collimating lens 225 to the focal planes of the first wafer 310 and the second wafer 320, respectively, and the reflected light of the focal planes of the first wafer 310 and the second wafer 320 may also pass through the beam splitter 221 again, and finally reach the image collector 223 to perform identification imaging of the first mark 330 and the second mark 340.

[0076] Preferably, the confocal optical system 220 may also include other lens components, including a first lens 226 and a second lens 227 that converge light beams to improve the clarity of the identification imaging. Specifically, the second lens 227 is disposed between the beam splitter 221 and the first wafer 310 and the second wafer 320 (the object to be measured), and the first lens 226 is disposed between the beam splitter 221 and the image collector 223. The light reflected by the beam splitter 221 is focused on the first wafer 310 and the second wafer 320 respectively by the second lens 227, and the light passing through the beam splitter 221 can be focused on the image collector 223 by the first lens 226. In this embodiment, since the light passes through the second lens 227 twice during the identification acquisition process of the image collector 223, the point image acquired by the image collector 223 is sharper, and the resolution capability of the confocal optical system 220 is further improved.

[0077] Since the light source in some embodiments of the present invention is an infrared light source 210, correspondingly, each component in the above-mentioned confocal optical system 220 can also be selected to be a component that cooperates with infrared light. For example, the image collector 223 can be an infrared camera, and the second lens 227 can also be an infrared objective lens.

[0078] In some embodiments of the invention, the motion mechanism (not shown in the drawings) in the wafer alignment device 200 may include a lateral moving part and a longitudinal moving part. Through the lateral moving part, the first wafer 310 and / or the second wafer 320 can be displaced laterally, that is, moved in the XY axis direction, which can be used for identification search. Through the longitudinal moving part, the first wafer 310 and / or the second wafer 320 can be displaced longitudinally, that is, moved in the Z axis direction, which can be used for identification focusing. Optionally, the lateral moving part and the longitudinal moving part can also be integrated together.

[0079] Optionally, the longitudinal moving part may further include a rotating shaft, wherein the rotating shaft may be connected to an angle adjustment motor, and the first wafer 310 and / or the second wafer 320 may be rotated at an angle, thereby further achieving identification focusing. In this embodiment, the motion mechanism may be controlled to perform X, Y, and Z three-axis movement and angle rotation to adjust the relative position between the first wafer 310 and the second wafer 320.

[0080] Next, please refer to Figure 5 and Figure 6 , Figure 5 A flowchart of a wafer bonding method provided according to some embodiments of the present invention is shown. Figure 6 A flow chart of a wafer bonding process provided according to some embodiments of the present invention is shown.

[0081] like Figure 5 As shown, in some embodiments of the present invention, the wafer bonding method may include the following steps: First, step S510 may be performed: obtaining a first wafer.

[0082] Combination Figure 2 and Figure 6 It is commonly understood that in some optional embodiments, the first wafer 310 is placed on the wafer by a supporting mechanism. For example, a suction cup structure can be used to fix and adsorb the first wafer 310. The first wafer 310 can be located at the top as an upper wafer, or it can be located at the bottom as a lower wafer. When the first wafer 310 is used as the upper wafer, since the infrared light source 210 and the confocal optical system 220 in the wafer alignment device 200 are both located at the top, optionally, the supporting mechanism for fixing the upper wafer can be a hole-digging structure, or it can be a supporting mechanism made of near-infrared transparent material, that is, the structure of the supporting mechanism can allow the infrared light emitted by the infrared light source 210 located at the top to pass through, and there is no limitation here.

[0083] Afterwards, step S520 may be performed: positioning the first mark on the second surface of the first wafer by using a wafer alignment device.

[0084] Specifically, combined Figure 2 , Figure 3and Figure 6 As shown, the infrared light beam emitted by the infrared light source 210 can pass through the second aperture 224 and the collimating lens 225, and then be reflected to the second lens 227 through the beam splitter 221, and focus on the first mark 330 on the second surface 312 of the first wafer 310. Then, the reflected light of the first mark 330 on the second surface 312 of the first wafer 310 can pass through the beam splitter 221 again, and finally reach the image collector 223 to display the first mark 330. The scattered light other than the first mark 330 and the scattered light of the second lens 227 will not reach the image collector 223, so that an image of the first mark 330 with a very high contrast can be obtained. Then, the first mark 330 of the first wafer 310 can be positioned in combination with the processor.

[0085] Afterwards, step S530 may be performed: obtaining a second wafer.

[0086] Can be combined Figure 2 and Figure 6 It is commonly understood that, optionally, the second wafer 320 can be placed on the wafer by a supporting mechanism, for example, a suction cup structure can be used to fix and absorb the first wafer 310. When the second wafer 320 is used as the lower wafer, since the infrared light source 210 and the confocal optical system 220 in the wafer alignment device 200 are both located above, the structure of the supporting mechanism for fixing the lower wafer may not be constrained.

[0087] Afterwards, step S540 may be executed: using a wafer alignment device, a second mark on the first surface of the second wafer is obtained for positioning.

[0088] Specifically, it can be combined Figure 2 , Figure 3 and Figure 6 As shown, the infrared light source 210 emits an infrared light beam which passes through the second aperture 224 and the collimating lens 225, and then is reflected to the second lens 227 via the beam splitter 221, and is focused on the second mark 340 on the first surface 321 of the second wafer 320. Then, the reflected light of the second mark 340 on the first surface 321 of the second wafer 320 can pass through the beam splitter 221 again, and finally reach the image collector 223, and the second mark 340 is displayed and imaged. However, the scattered light other than the second mark 340 and the scattered light of the second lens 227 will not reach the image collector 223, so that an image of the second mark 340 with a very high contrast can be obtained. Then, the second mark 340 of the second wafer 320 can be positioned in combination with the processor.

[0089] Afterwards, step S550 may be performed: adjusting the relative position of the first wafer and the second wafer based on the position difference between the first mark and the second mark.

[0090] Specifically, it can be combined Figure 3 and Figure 6 As shown, based on the position difference between the first mark 330 and the second mark 340 calculated by the processor, the lateral moving part in the motion mechanism can be controlled to make the first wafer 310 and / or the second wafer 320 move laterally, that is, move in the XY axis direction, to find the mark. In addition, the longitudinal moving part in the motion mechanism can also be controlled to make the first wafer 310 and / or the second wafer 320 move longitudinally, that is, move in the Z axis direction, to focus the mark. Furthermore, the first wafer 310 and / or the second wafer 320 can also be rotated by the rotation axis to further achieve mark focusing.

[0091] Finally, step S560 may be performed: in response to the first mark and the second mark being vertically aligned, the first wafer and the second wafer are pressed together to complete wafer bonding.

[0092] like Figure 6 As shown, before wafer bonding, the first wafer 310 and the second wafer 320 can be identified and aligned in real time by the alignment marks. When the first mark 330 and the second mark 340 are vertically aligned, the first wafer 310 can be pressed down to bond the upper and lower wafers.

[0093] Although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or concurrently with other actions from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art.

[0094] In summary, the present invention provides a wafer alignment device, a wafer bonding device, and a computer-readable storage medium, which can avoid the alignment error caused by the optical axis deviation of the two optical systems corresponding to the two wafers, and the movement error caused by the motion platform avoiding to obtain the wafer mark on the other side, thereby improving the positioning accuracy and further improving the wafer bonding accuracy.

[0095] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wafer alignment device, characterized in that: include: an infrared light source, providing an infrared light beam for aligning the first wafer and the second wafer; a confocal optical system, located on one side of the first wafer, for transmitting the infrared light beam through the first wafer to the second surface of the first wafer and the first surface of the second wafer opposite thereto, so as to respectively obtain the positioning of the first mark on the second surface and the second mark on the first surface; as well as A motion mechanism is respectively connected to the first wafer and the second wafer, and based on the positioning of the first marker and the second marker, moves the position of the first wafer and / or the second wafer so as to vertically align the first marker and the second marker with the aid of the infrared light beam.

2. The wafer alignment device according to claim 1, characterized in that: The infrared light source is an adjustable light source, which is used to switch infrared light beams of different bands according to the type of thin film prepared on the surface of the wafer.

3. The wafer alignment device according to claim 1, characterized in that: The second surface of the first wafer includes at least two of the first markings, and the first surface of the second wafer includes at least two of the second markings, and the at least two first markings and the at least two second markings are used to determine the moving deflection angle of the first wafer and / or the second wafer.

4. The wafer alignment device according to claim 3, characterized in that: include: At least two groups of the confocal optical systems and their corresponding infrared light sources are distributed on the same side of the first wafer and are used to image the first mark on the second surface of the first wafer and the second mark on the first surface of the second wafer.

5. The wafer alignment device according to claim 4, characterized in that: At least two groups of the confocal optical systems and their corresponding infrared light sources are symmetrical about the center of the first wafer, and the at least two first marks on the first wafer are used as alignment references.

6. The wafer alignment device according to claim 1, characterized in that: The confocal optical system comprises a first aperture, a second aperture, and an image collector, wherein the first aperture and the second aperture are located at a conjugate plane of a focal plane of the first wafer and the second wafer, wherein the first aperture is located in front of the image collector, and the second aperture is located in front of the infrared light source. The infrared light beam emitted by the infrared light source becomes a point light source after passing through the second aperture and is respectively focused on the first mark on the focal plane of the first wafer and the second mark on the focal plane of the second wafer, and the image collector only receives images of the first mark and the second mark formed by the light focused by the first aperture.

7. The wafer alignment device according to claim 6, characterized in that: The confocal optical system includes a beam splitter located at the intersection of the optical axis of the infrared light source and the optical axis of the image display, so as to reflect the infrared light beam emitted by the infrared light source to the focal planes of the first wafer and the second wafer respectively. The reflected light from the focal planes of the first wafer and the second wafer then passes through the beam splitter and reaches the image display to perform identification imaging of the first mark and the second mark.

8. The wafer alignment device according to claim 7, characterized in that: The confocal optical system comprises a second aperture and a collimating lens, wherein the second aperture is located between the infrared light source and the beam splitter, and the collimating lens is located between the second aperture and the beam splitter, and is used to filter the light source of the non-focusing surface.

9. The wafer alignment device according to claim 1, characterized in that: The motion mechanism includes a lateral moving part and a longitudinal moving part. The lateral moving part can be used to laterally displace the first wafer and / or the second wafer for identification search, and the longitudinal moving part can be used to longitudinally displace the first wafer and / or the second wafer for identification focusing.

10. The wafer alignment device according to claim 9, characterized in that: The longitudinal moving part also includes a rotating shaft, which is used to rotate the first wafer and / or the second wafer at an angle to perform marking focusing.

11. A wafer bonding method, characterized in that: The following steps are involved: Obtaining a first wafer; positioning a first mark on the second surface of the first wafer by using the wafer alignment device according to any one of claims 1 to 10; obtaining a second wafer; Acquire a second mark on the first surface of the second wafer for positioning by the wafer alignment device; Adjusting the relative position of the first wafer and the second wafer based on the position difference between the first mark and the second mark; as well as In response to the first mark and the second mark being vertically aligned, the first wafer and the second wafer are pressed together to complete wafer bonding.

12. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the computer instructions are executed by a processor, the wafer bonding method according to claim 11 is implemented.

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