Optical alignment apparatus for die bonding and method of alignment thereof

Abstract

The application relates to the technical field of chip bonding, and particularly discloses an optical alignment device for chip bonding and an alignment method thereof, wherein the device comprises a DUV laser, a first mirror group, a second mirror group, an inner two-way reflection prism, a first DUV objective lens, a second DUV objective lens and an imaging assembly; the device significantly improves the optical resolution of the system by introducing a DUV laser light source and a matching DUV objective lens, and meets the demand for high-precision alignment; meanwhile, the device innovatively adopts the inner two-way reflection prism to combine two DUV objective lenses to construct a double-path light path structure, effectively solves the problem of simultaneous alignment of upper and lower surfaces, and improves the adaptability of the system to handle the double-surface alignment working condition; and the imaging assembly of the device synchronously collects two-way sample light signals, one-time obtains the images of a wafer and a chip, and completely eliminates the influence of time drift and motion factors on alignment accuracy, so that the overall improvement of alignment accuracy is guaranteed at the hardware level.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chip bonding, in particular to an optical alignment device for chip bonding and an alignment method thereof. BACKGROUND

[0002] Chip bonding optical alignment technology plays a key role in the fields of semiconductor manufacturing, 3D integration and MEMS, especially in direct D2W bonding process, which promotes the development of microelectronics industry towards miniaturization and high integration. The current trend focuses on using image recognition and special lasers to improve alignment accuracy and speed to meet the needs of advanced processes, promote the optimization of packaging process and cost reduction.

[0003] However, the existing optical alignment system faces significant challenges in the D2W bonding process: the system is not adaptable enough to effectively handle the top-down alignment condition, which limits the alignment accuracy, and generally uses two imaging components to capture images of the chip and wafer respectively for position positioning and alignment, which is easily affected by time drift and motion, resulting in poor alignment accuracy. In addition, these systems generally use visible or infrared light illumination for image acquisition, which is constrained by optical resolution and cannot achieve nanometer-level precision requirements, affecting the bonding quality and yield.

[0004] At present, there is no effective technical solution to the above problems. SUMMARY

[0005] The purpose of the present application is to provide an optical alignment device for chip bonding and an alignment method thereof to improve the alignment accuracy of the bonding process and avoid the influence of time drift and motion on the alignment accuracy.

[0006] In a first aspect, the present application provides an optical alignment device for chip bonding for simultaneously acquiring wafer and chip positions for alignment bonding, comprising: a DUV laser, a first mirror group, a second mirror group, an internal two-way reflective prism, a first DUV objective lens, a second DUV objective lens and an imaging assembly.

[0007] The output ends of the DUV laser are connected to the first mirror group and the second mirror group through two light guide fibers respectively to transmit laser to the first mirror group and the second mirror group respectively;

[0008] The first DUV objective lens and the second DUV objective lens are arranged on the two sides of the internal two-way reflective prism respectively and face opposite directions;

[0009] The internal two-way reflective prism is used to reflect the laser output by the first mirror group and the second mirror group to the first DUV objective lens and the second DUV objective lens respectively to project onto the sample;

[0010] The inner bidirectional reflecting prism is also used for reflecting sample light received by the first DUV objective lens and the second DUV objective lens to the first mirror group and the second mirror group respectively, so that the first mirror group and the second mirror group reflect the sample light to the imaging assembly.

[0011] By introducing a DUV laser light source and a matching DUV objective lens, the optical resolution of the system is significantly improved to meet the demand for high-precision alignment. Meanwhile, the inner bidirectional reflecting prism is innovatively combined with two DUV objective lenses to construct a double-path light path structure, effectively solving the problem of simultaneous alignment of the upper and lower surfaces and improving the adaptability of the system to handle double-surface alignment conditions. The imaging assembly synchronously collects two-way sample light signals, and the images of the wafer and the chip are obtained at one time, completely eliminating the influence of time drift and motion factors on alignment accuracy, thereby ensuring the overall improvement of alignment accuracy at the hardware level.

[0012] The optical alignment device for chip bonding, wherein the first mirror group and the second mirror group each include a fiber coupling collimating mirror, a first reflecting prism, a lens group, and a first light splitting prism arranged in sequence according to the laser transmission direction, the first light splitting prism is used for outputting laser to the inner bidirectional reflecting prism and reflecting the sample light to the imaging assembly.

[0013] Through the above design, the device of the present application ensures that the laser output from the DUV laser can be effectively processed into a light beam with the required size and characteristics and projected onto the sample. At the same time, this structure ensures that the sample light reflected from the sample can be efficiently transmitted and reflected to the imaging assembly.

[0014] The optical alignment device for chip bonding, wherein the device further includes a collimating assembly, and the first mirror group and the second mirror group further include a second light splitting prism arranged between the first reflecting prism and the lens group, the second light splitting prism is also used for reflecting part of the light of the sample light through the first light splitting prism and the lens group to the collimating assembly.

[0015] The optical alignment device for chip bonding, wherein the collimating assembly includes a third light splitting prism, a relay lens group, and a collimator camera arranged in sequence according to the light transmission direction.

[0016] The optical alignment device for chip bonding, wherein the first mirror group and the second mirror group are symmetrically arranged on both sides of the inner bidirectional reflecting prism.

[0017] The optical alignment device for chip bonding, wherein the imaging assembly includes a low-pass filter, an imaging tube lens, and a DUV area array camera arranged in sequence according to the sample light transmission direction.

[0018] The optical alignment device for chip bonding, wherein the imaging assembly further comprises a double-face reflecting prism and two second reflecting prisms, the two second reflecting prisms are respectively used for reflecting the sample light reflected by the first mirror group and the second mirror group to two reflecting surfaces of the double-face reflecting prism, so that the double-face reflecting prism reflects the two sample lights in parallel to the low-pass filter.

[0019] The optical alignment device for chip bonding, wherein the DUV area array camera is divided into imaging areas respectively used for receiving the two sample lights for imaging.

[0020] The optical alignment device for chip bonding, wherein the first DUV objective lens and the second DUV objective lens are symmetrically arranged on the upper and lower sides of the inner two-way reflecting prism.

[0021] In a second aspect, the present application further provides an alignment method of the optical alignment device for chip bonding provided in the first aspect, the optical alignment device for chip bonding is installed in a bonder, the first DUV objective lens and the second DUV objective lens are respectively used for upwardly collecting sample light of a chip as a sample and downwardly collecting sample light of a wafer as a sample.

[0022] The alignment method comprises the following steps:

[0023] S1, simultaneously collecting image data containing alignment marks on the chip and the wafer based on the imaging assembly;

[0024] S2, analyzing the alignment mark in the image data to locate the positions of the chip and the wafer, and calculating the coordinate deviation between the two, so that the bonder adjusts the positions of the chip and / or the wafer according to the coordinate deviation.

[0025] The method of the present application utilizes the simultaneous imaging capability of the optical alignment device, realizes the synchronous acquisition of the chip and wafer image data at the method level, thereby eliminating the error introduced by the different synchronization of the acquisition time or the position change in the motion process when calculating the position deviation, effectively overcoming the adverse effects of time drift and motion on the alignment effect, and improving the alignment precision of chip bonding.

[0026] From the above, the application provides an optical alignment device for chip bonding and an alignment method thereof. The device of the application introduces a DUV laser light source and a matching DUV objective lens, which significantly improves the optical resolution of the system and meets the demand for high-precision alignment. Meanwhile, the device innovatively adopts an inner two-way reflecting prism combined with two DUV objective lenses to construct a double-path light path structure, effectively solving the problem of simultaneous alignment of the upper and lower surfaces and improving the adaptability of the system to handle double-sided alignment conditions. The imaging assembly of the device synchronously collects two light signals of the sample and obtains the images of the wafer and the chip at one time, completely eliminating the influence of time drift and motion factors on the alignment accuracy, thereby ensuring the overall improvement of the alignment accuracy at the hardware level. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 and Figure 2 A downward sectional structure schematic diagram of the optical alignment device for chip bonding provided by the embodiments of the application.

[0028] Figure 3 A forward sectional structure schematic diagram of the optical alignment device for chip bonding provided by the embodiments of the application.

[0029] Figure 4 A region division schematic diagram of a target surface of a DUV area array camera.

[0030] Figure 5 A flowchart of the alignment method provided by some embodiments of the application.

[0031] Figure 6 A flowchart of the alignment method provided by some embodiments of the application.

[0032] Reference signs: 1, DUV laser; 2, first mirror group; 3, second mirror group; 4, inner two-way reflecting prism; 5, first DUV objective lens; 6, second DUV objective lens; 7, imaging assembly; 8, collimation assembly; 11, light guide optical fiber; 21, optical fiber coupling collimation mirror; 22, first reflecting prism; 23, lens group; 24, first light splitting prism; 25, second light splitting prism; 81, third light splitting prism; 82, relay lens group; 83, collimator camera; 71, low-pass filter; 72, imaging tube mirror; 73, DUV area array camera; 74, double-sided reflecting prism; 75, second reflecting prism; 731, imaging region; 732, target surface; 733, illumination region. DETAILED DESCRIPTION

[0033] Embodiments of the present application are described below in detail with reference to the accompanying drawings, wherein the same or similar components are denoted by the same or similar reference numerals, and thus repeated description is omitted. The embodiments described below are examples for explaining the present application, and are not intended to limit the present application.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate the orientation or positional relationship shown in the drawings, and are merely used for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0035] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "under", "below" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0037] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplification, the elements of the particular examples are described in the following disclosure. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application can repeatedly refer to reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides various specific examples of processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0038] In a first aspect, refer to Figures 1-4 Some embodiments of the present application provide an optical alignment device for chip bonding, which is used to simultaneously obtain the positions of a wafer and a chip for alignment bonding, and the device comprises a DUV laser 1, a first mirror group 2, a second mirror group 3, an internal two-way reflecting prism 4, a first DUV objective lens 5, a second DUV objective lens 6 and an imaging assembly 7.

[0039] The output end of the DUV laser 1 respectively transmits laser to the first mirror group 2 and the second mirror group 3 through two light guide fibers 11 respectively;

[0040] The first DUV objective lens 5 and the second DUV objective lens 6 are respectively arranged on the two sides of the internal two-way reflecting prism 4 and face opposite directions;

[0041] The internal two-way reflecting prism 4 is used to reflect the laser output by the first mirror group 2 and the second mirror group 3 to the first DUV objective lens 5 and the second DUV objective lens 6 respectively to project on a sample;

[0042] The internal two-way reflecting prism 4 is also used to reflect the sample light received by the first DUV objective lens 5 and the second DUV objective lens 6 to the first mirror group 2 and the second mirror group 3 respectively, so that the first mirror group 2 and the second mirror group 3 reflect the sample light into the imaging assembly 7.

[0043] Specifically, the DUV laser 1 refers to a light source that outputs deep ultraviolet band laser, which can be implemented by using a quasi-molecule laser or a solid laser frequency multiplication, etc., and is mainly used to provide a short-wavelength light source and improve the optical resolution of the system; the internal two-way reflective prism 4 refers to an optical prism with two reflecting surfaces, which can simultaneously process and reflect light from two directions to other directions, and is used to reflect two incident lights to different directions and reflect two return lights to the same direction, so as to realize sharing of the two light paths; the DUV objective lens refers to an objective lens with a working wavelength in the deep ultraviolet range, which can be implemented by using a DUV transmission material such as fused quartz, calcium fluoride, etc., and special design, and is mainly used to image the sample or project light onto the sample under high resolution; the imaging assembly 7 refers to an assembly for receiving light and converting it into image data, which can be implemented by using a filter, an imaging lens, a camera, etc., and is mainly used to receive two sample lights and simultaneously image them to obtain sample position information.

[0044] Specifically, the laser emitted by the DUV laser 1 is guided to the first mirror group 2 and the second mirror group 3 through two light guide fibers 11. The first mirror group 2 and the second mirror group 3 process the received laser, for example, shape or expand the beam. The internal two-way reflective prism 4 receives the light beams from the first mirror group 2 and the second mirror group 3, and reflects them to the first DUV objective lens 5 and the second DUV objective lens 6, respectively. The first DUV objective lens 5 and the second DUV objective lens 6 project light onto the wafer and the chip as samples, respectively. The light reflected by the samples (sample light) enters the internal two-way reflective prism 4 again through the respective DUV objective lenses. The internal two-way reflective prism 4 reflects the sample light from the first DUV objective lens 5 and the second DUV objective lens 6 back to the first mirror group 2 and the second mirror group 3. The first mirror group 2 and the second mirror group 3 reflect the sample light to the imaging assembly 7. The imaging assembly 7 receives the sample light from the two light paths and simultaneously images them, thereby obtaining image data of the wafer and the chip. By analyzing these simultaneously obtained image data, the positions of the wafer and the chip can be determined, the deviation between them can be calculated, and alignment adjustment can be performed.

[0045] The device of the present application significantly improves the optical resolution of the system by introducing a DUV laser light source and a matching DUV objective lens, and meets the demand for high-precision alignment. At the same time, the internal two-way reflective prism 4 is innovatively used in combination with two DUV objective lenses to construct a double-path light path structure, effectively solving the problem of simultaneous alignment of the upper and lower surfaces and improving the adaptability of the system to handle double-sided alignment conditions. Through the imaging assembly 7, the two sample light signals are synchronously collected, and the images of the wafer and the chip are obtained at one time, thereby completely eliminating the influence of time drift and motion factors on the alignment accuracy, and thus ensuring the overall improvement of the alignment accuracy at the hardware level.

[0046] In some preferred embodiments, the first lens group 2 and the second lens group 3 both include a fiber-coupled collimator 21, a first reflecting prism 22, a lens group 23, and a first beam splitter prism 24, which are arranged in sequence according to the laser transmission direction. The first beam splitter prism 24 is used to output the laser to the internal bidirectional reflection prism 4, and to reflect the sample light into the imaging component 7.

[0047] Specifically, the fiber-coupled collimator 21 is an optical component used to convert a light beam with a certain divergence angle output from an optical fiber into a parallel light beam; the first reflecting prism 22 is an optical element used to change the propagation direction of the light beam; the lens group 23 is an optical system composed of one or more lenses, used to focus, diverge, collimate or change the size of the light beam, etc., which can be achieved by a complex structure composed of multiple single lenses, doublets or triplets;

[0048] Specifically, based on the above-described device structure, laser light output from a DUV laser 1 via a light-guiding optical fiber 11 enters the first and second lens groups 2 and 3. Within each lens group, the laser light is first received by a fiber-coupled collimator 21 and processed into a parallel, collimated beam. This parallel beam then enters the first reflecting prism 22, where the optical path is bent 90°, changing the beam's propagation direction. The bent beam then passes through a lens group 23 and a first beam-splitting prism 24. The lens group 23 and the first beam-splitting prism 24 cooperate to expand the laser light to achieve a spot size and beam characteristics suitable for projecting onto the sample. After passing through the first beam-splitting prism 24, the processed laser light is directed to an internal bidirectional reflection prism 4. The internal bidirectional reflection prism 4 reflects this portion of the laser light to the corresponding DUV objective lens, ultimately projecting it onto the sample, thereby illuminating the sample. The sample light reflected from the sample passes through the corresponding DUV objective lens and the internal bidirectional reflection prism 4 before re-entering the first beam-splitting prism 24. Another function of the first beam splitter prism 24 is to reflect this portion of sample light toward the imaging assembly 7. By arranging these optical components in a specific order, the lens assembly not only effectively processes the incident laser light, ensuring the quality of the illumination beam and the characteristics of the light spot projected onto the sample, but also efficiently receives and guides the sample light toward the imaging assembly 7. This structural design provides a stable and reliable optical path for the entire optical alignment device, ensuring precise alignment of the illumination and imaging light paths, thereby enabling the device to achieve high-precision alignment. This specific optical path design resolves optical performance issues caused by an ambiguous lens assembly structure, enabling the entire device to effectively process DUV laser light and sample light, meeting the requirements of high-precision alignment.

[0049] Through the above design, the device of the present application ensures that the laser light output from the DUV laser 1 can be effectively processed into a beam with the required size and characteristics and projected onto the sample. At the same time, this structure ensures that the sample light reflected from the sample can be efficiently transmitted and reflected to the imaging component 7.

[0050] In some preferred embodiments, the device further comprises a collimation assembly 8, and the first mirror group 2 and the second mirror group 3 further comprise a second light splitting prism 25 arranged between the first reflecting prism 22 and the lens group 23, and the second light splitting prism 25 is further configured to reflect part of the sample light passing through the first light splitting prism 24 and the lens group 23 to the collimation assembly 8.

[0051] Specifically, the collimation assembly 8 refers to a device for receiving light and analyzing the angle thereof to determine whether the light beam is parallel or the angle of deviation from the parallel state, which can be implemented by a system composed of a lens, a photodetector and a signal processing unit, or by a sensor based on the principle of Moire fringes or interference.

[0052] Specifically, the technical scheme further introduces a technical means for measuring the inclination of the sample on the basis of the aforementioned optical alignment device to solve the problem of insufficient accuracy of alignment relying only on planar position information. The core of the above design lies in the addition of the collimation assembly 8 and the second light splitting prism 25, and the integration of the second light splitting prism 25 into the first mirror group 2 and the second mirror group 3. The second light splitting prism 25 is arranged between the first reflecting prism 22 and the lens group 23. After the sample light returns from the sample and enters the mirror group through the inner two-way reflecting prism 4, it will pass through the first light splitting prism 24 and the lens group 23 in turn. After passing through the lens group 23, before reaching the first reflecting prism 22, the sample light beam will encounter the newly added second light splitting prism 25. The second light splitting prism 25 is configured to reflect the sample light passing through the first light splitting prism 24 and the lens group 23 to the newly added collimation assembly 8. By reflecting the sample light to the collimation assembly 8, the system creates an independent light path that is specifically used for analyzing the angle information of the sample light, rather than for imaging. The collimation assembly 8 receives this part of the split sample light and analyzes it to measure the inclination of the corresponding sample. The inclination of the sample will cause the angle of the reflected light to change, and the collimation assembly 8 can detect and quantify this angle deviation to obtain accurate inclination information of the sample.

[0053] The present scheme can obtain the inclination information of the sample while obtaining the sample position image information. The measurement capability of the inclination, combined with the original planar position measurement capability, enables the alignment system to perform more comprehensive spatial correction, not only correcting the planar position deviation, but also compensating for the angular deviation of the sample. In this way, the device can simultaneously obtain the planar position and inclination information of the sample, extending two-dimensional alignment to three-dimensional spatial alignment, significantly improving the accuracy of alignment, overcoming the limitations of alignment relying only on two-dimensional image information, significantly improving the alignment accuracy of chip bonding, and being particularly suitable for advanced packaging processes with extremely high precision requirements, thereby improving the quality and yield of bonding.

[0054] In some preferred embodiments, the collimation assembly 8 comprises a third beam splitter 81, a relay lens group 82 and a collimator camera 83 arranged in sequence along the light transmission direction.

[0055] Specifically, the relay lens group 82 refers to a system composed of one or more lenses, used to reimage or adjust the characteristics of the light beam in the optical system, such as changing the beam diameter, convergence angle or correcting aberration. It can be realized by a lens system composed of multiple spherical or aspherical lenses. The collimation assembly 8 refers to a device that combines a collimation optical system and an image sensor, the collimator camera 83 is used to receive light and convert it into an electrical signal to form an image, and the collimation assembly 8 is commonly used to measure the collimation of the light beam or determine the tilt angle of the object reflecting surface by analyzing the image. In the embodiments of the present application, the collimation assembly 8 is preferably an optoelectronic autocollimator.

[0056] Specifically, the third beam splitter 81 serves as the first optical element for the light entering the collimation assembly 8, which is used to receive the sample light reflected from the second beam splitter 25 and guide it into the subsequent optical path, preparing for the tilt measurement. The relay lens group 82 is arranged after the third beam splitter 81, which is used to process the incoming light, such as re-imaging or adjusting the light beam, to optimize the light beam quality and ensure that the light enters the collimator camera 83 in a suitable state, improving the accuracy of the measurement. The collimator camera 83 is arranged after the relay lens group 82 and is the core measurement element of the collimation assembly 8, which is used to receive the processed sample light and convert it into image data. By analyzing these image data, the tilt of the sample can be accurately calculated, thereby providing key attitude information for the alignment adjustment of the bonder. This specific optical path design, combined with the precise composition of the collimation assembly 8, enables the device to split a part of the sample light from the main imaging light path for dedicated tilt measurement, while the main light path is used for position imaging, thereby increasing the ability to obtain attitude information of the sample without interfering with the main alignment function.

[0057] In some preferred embodiments, the first mirror group 2 and the second mirror group 3 are symmetrically arranged on both sides of the inner two-way reflecting prism 4.

[0058] Specifically, by symmetrically arranging the first mirror group 2 and the second mirror group 3 on both sides of the inner two-way reflecting prism 4, it can be ensured that the two sample lights reflected from the sample have high consistency in the optical path and optical processing when passing through the respective mirror groups and the inner two-way reflecting prism 4 to reach the imaging assembly 7. This significantly reduces the differences that may exist between the two light paths in terms of optical path, magnification, distortion, aberration, etc. As a result, the two images of the chip and wafer formed simultaneously on the imaging assembly 7 will have higher similarity and comparability, for example, the scale, shape and clarity of the images will be more consistent. The consistency of such optical characteristics provides a more reliable basis for subsequent image-based alignment mark positioning and coordinate deviation calculation, making the calculation results more accurate. Therefore, the symmetrically arranged first mirror group 2 and second mirror group 3 work together with the inner two-way reflecting prism 4 and the shared imaging assembly 7 to effectively improve the alignment accuracy of the simultaneous imaging scheme, solving the problem of limited alignment accuracy due to differences between the two light paths.

[0059] In some preferred embodiments, the imaging assembly 7 includes a low-pass filter 71, an imaging tube lens 72 and a DUV area array camera 73 arranged in sequence according to the sample light transmission direction.

[0060] Specifically, the low-pass filter 71 is used to filter out visible light and can be implemented using a dielectric film filter or an absorption filter. The imaging tube lens 72 is used to converge or convert the light from the objective lens into parallel light and form an image on the subsequent detector, so that the two sample lights can be combined and imaged on the DUV area array camera 73. The DUV area array camera 73 refers to an image sensor that has the ability to respond to deep ultraviolet light and can convert the received deep ultraviolet light signal into an electrical signal and output image data in the form of a two-dimensional array (area array). It can be implemented using a DUV sensitive sensor based on CMOS or CCD technology.

[0061] Specifically, the two-way sample light from the wafer and the chip passes through the internal double-directional reflecting prism 4, the first mirror group 2 and the second mirror group 3 in the device, and is guided to the imaging assembly 7. After entering the imaging assembly 7, the sample light first passes through the low-pass filter 71 for filtering out visible light. The filter ensures that only the effective signal light in the DUV band can continue to propagate, while the ambient light or stray visible light is filtered out, thereby improving the contrast and signal-to-noise ratio of the image. Then, the light passing through the filter enters the imaging tube lens 72 for combined imaging. The imaging tube lens 72 is the key to realizing simultaneous imaging, which receives two independent sample lights from the wafer and the chip and performs optical processing on them, so that the two light rays can form clear images on the subsequent DUV area array camera 73 at the same time. Finally, the DUV area array camera 73 receives the light processed by the imaging tube lens 72, converts it into an electrical signal, and forms digital data containing images of the wafer and the chip. Since the device uses the internal double-directional reflecting prism 4, the first DUV objective lens 5 and the second DUV objective lens 6 to collect sample light from the wafer and the chip respectively, and guides the two light rays through the first mirror group 2 and the second mirror group 3 to the same imaging assembly 7, combined with the combined imaging function of the imaging tube lens 72 in the imaging assembly 7, the single imaging assembly 7 can capture images of two types of samples at the same time. This design avoids the use of two independent imaging systems, thereby eliminating the alignment error caused by the possible time drift or relative motion between the two systems, and improving the alignment accuracy.

[0062] In some preferred embodiments, the imaging assembly 7 further comprises a double-face reflecting prism 74 and two second reflecting prisms 75, which are respectively used to reflect the sample light reflected by the first mirror group 2 and the second mirror group 3 to two reflecting surfaces of the double-face reflecting prism 74, so that the double-face reflecting prism 74 reflects the two sample lights in parallel to the low-pass filter 71.

[0063] Specifically, the double-face reflecting prism 74 refers to an optical element with two reflecting surfaces, which can be implemented by a right-angle prism, a roof prism or other optical elements with two reflecting surfaces.

[0064] Specifically, the two second reflecting prisms 75 receive the sample light from the first lens group 2 and the second lens group 3, respectively, and reflect it onto two different reflective surfaces of the double-sided reflecting prism 74. The double-sided reflecting prism 74, using its two reflective surfaces, further reflects the two sample light beams, aligning them into parallel beams. These two parallel beams are then directed to the low-pass filter 71. This design ensures that the two sample light beams from the wafer and chip enter the shared imaging optical path consisting of the low-pass filter 71, imaging tube lens 72, and DUV area array camera 73 in a predetermined, parallel spatial relationship. This enables a single imaging assembly 7 to simultaneously receive and process both streams of information, providing the optical foundation for subsequent synchronized image acquisition and alignment calculations. The double-sided reflecting prism 74 and second reflecting prism 75 structure provided by the above design effectively and appropriately directs the two sample light beams from the first lens group 2 and the second lens group 3 into the imaging assembly 7. This combination enables a single imaging assembly 7 to simultaneously process two independent sample light beams, overcoming the temporal drift and motion effects associated with the need for two imaging assemblies 7 in the prior art. The key to achieving simultaneous alignment is to cleverly converge the two beams of light and introduce them in parallel into a single imaging component 7.

[0065] In some preferred embodiments, the DUV area array camera 73 is divided into imaging areas 731 for receiving two sample lights for imaging.

[0066] Specifically, the DUV area array camera 73 is a rectangular area array sensor. A rectangular area array sensor refers to a two-dimensional pixel array with an overall rectangular shape. The division of imaging areas 731, each for receiving two sample beams for imaging, means that the rectangular sensor's photosensitive surface is logically or physically divided into at least two independent areas, each specifically designed to receive sample light from a different sample (e.g., a wafer and a chip) and form a corresponding image. This division can be achieved through optical system design, where light beams from different samples are guided and projected onto predetermined distinct areas on the sensor. Alternatively, subsequent image processing software can be used to define different areas on the sensor as independent imaging areas 731 for processing.

[0067] More specifically, the above design is combined with the optical path design in the device that converges the two sample lights to the imaging component 7, realizing the function of synchronous and independent imaging with a single sensor, and solving the interference problem of dual-sample synchronous imaging in the prior art.

[0068] More specifically, if Figure 4 As shown, the DUV area array camera 73 forms two illumination areas 733 on the target surface 732 of the camera during the imaging process, and a corresponding imaging area 731 is provided in each illumination area 733 .

[0069] In some preferred embodiments, the first DUV objective 5 and the second DUV objective 6 are symmetrically arranged on the upper and lower sides of the inner two-way reflecting prism 4.

[0070] Specifically, the above arrangement is highly consistent with the common placement of chips and wafers in the chip bonding process. By arranging the two objectives above and below the inner two-way reflecting prism 4, one objective can be more easily aligned and optically interacted (projecting laser and receiving sample light) with the sample (e.g. chip) located above, while the other objective can be more easily aligned and optically interacted with the sample (e.g. wafer) located below. This specific symmetrical layout optimizes the matching of the optical path and the sample position, enabling the device to more efficiently and stably acquire optical information of the upper and lower samples simultaneously, thereby providing a better foundation for subsequent image acquisition and alignment calculation. Combined with the ability of the existing scheme to simultaneously image the wafer and chip using the inner two-way reflecting prism 4 and the imaging assembly 7, this symmetrical layout of the objectives enables the simultaneous imaging function to better serve the samples placed above and below, improving the efficiency and accuracy of the overall alignment process. Symmetrical arrangement also helps to simplify the mechanical design of the system and the optical alignment and calibration process.

[0071] In a second aspect, referring to Figure 5 and Figure 6 some embodiments of the present application also provide an alignment method for the optical alignment device for chip bonding provided in the first aspect, which is installed in a bonder, and the first DUV objective 5 and the second DUV objective 6 are respectively used to collect sample light of a chip as a sample upward and sample light of a wafer as a sample downward;

[0072] The alignment method comprises the following steps:

[0073] S1, based on the imaging assembly 7, simultaneously collecting image data about the chip and the wafer containing alignment marks;

[0074] S2, analyzing the alignment marks in the image data to locate the positions of the chip and the wafer, and calculating the coordinate deviation between them, so that the bonder adjusts the position of the chip and / or the wafer according to the coordinate deviation.

[0075] Specifically, simultaneously acquiring image data containing alignment marks on the chip and wafer refers to acquiring visual information of the chip and wafer respectively by imaging assembly 7 through one-time imaging; analyzing the alignment marks in the image data to locate the positions of the chip and wafer refers to identifying the preset alignment marks (Mark) in the image through image processing technology to determine the specific positions of the alignment marks in the image coordinate system, which can be realized by using image recognition algorithms such as template matching and feature point detection. Calculating the coordinate deviation between the two refers to calculating the relative displacement of the chip relative to the wafer in the horizontal and / or vertical direction according to the located positions of the alignment marks of the chip and wafer, which can be realized by simple coordinate subtraction or more complex coordinate transformation calculation. The process of adjusting the position can be realized according to the preset adjustment algorithm and the coordinate deviation, and the preset adjustment algorithm refers to a set of instructions or models stored in the control system of the bonder, which is used to determine the accurate movement amount and direction of the chip and / or wafer according to the calculated coordinate deviation.

[0076] Specifically, the present scheme proposes a method of chip bonding alignment using a specific optical alignment device, aiming to solve the precision problem caused by time drift and motion in traditional alignment methods. The method takes advantage of the ability of the first DUV objective lens 5 and the second DUV objective lens 6 in the device to collect chip and wafer sample light respectively, and emphasizes the steps of the alignment method. First, step S1 acquires image information containing alignment marks on the chip and wafer at the same time, which directly utilizes the simultaneous imaging capability of the aforementioned device, avoiding the relative position errors that may be caused by the time interval of traditional image acquisition or the use of independent imaging systems. These errors are usually caused by small motion or system drift within the time interval of image acquisition. Then, step S2 precisely locates the positions of the chip and wafer in the image by identifying the preset alignment marks in the image, and calculates the coordinate deviation between the two. Since the images are acquired simultaneously, the calculated coordinate deviation accurately reflects the relative position relationship between the chip and wafer at the time of acquisition. Then, this real-time and synchronous coordinate deviation information is transmitted to the bonder. The bonder accurately adjusts the positions of the chip and / or wafer according to this coordinate deviation and the preset adjustment algorithm. This adjustment based on simultaneous data acquisition ensures the real-time and accuracy of the alignment process. The device has the ability to simultaneously receive sample light from the wafer and the chip and make the imaging assembly 7 simultaneously image the two types of samples, which provides the basis for the simultaneous acquisition step in the method. By utilizing this hardware capability to achieve simultaneous acquisition in the method, the calculated position deviation can accurately reflect the relative position of the chip and wafer at the same time, making the subsequent adjustment more accurate and effectively overcoming the adverse effects of time drift and motion on the alignment effect.

[0077] By the above scheme, the method of the present application utilizes the simultaneous imaging capability of the optical alignment device to achieve synchronous acquisition of chip and wafer image data at the method level, thereby eliminating errors introduced by different acquisition times or position changes during movement when calculating the position deviation, effectively overcoming the adverse effects of time drift and movement on the alignment effect, and improving the alignment precision of chip bonding.

[0078] In some preferred embodiments, in the embodiments in which the aforementioned device comprises the collimation assembly 8, the method further comprises a step performed between step S1 and step S2:

[0079] SA, acquiring the inclination of the chip and / or wafer based on the collimation assembly 8;

[0080] The step of adjusting the position of the chip and / or wafer according to the coordinate deviation by the bonder comprises:

[0081] Adjusting the position of the chip and / or wafer according to the coordinate deviation, the inclination, and a preset adjustment algorithm.

[0082] Specifically, acquiring the inclination of the chip and / or wafer refers to optical measurement of the sample surface by the collimation assembly 8 to obtain the angular deviation thereof relative to the reference plane. The collimator camera 83 captures the spot image, and the position or shape change of the spot is analyzed by an image processing algorithm to accurately calculate the inclination angles of the chip and / or wafer in two orthogonal directions, such as the pitch angle and the yaw angle.

[0083] More specifically, adjusting the position of the chip and / or wafer according to the coordinate deviation, the inclination, and a preset adjustment algorithm refers to that when adjusting the position of the sample, the bonder no longer relies only on the X-Y coordinate deviation in the plane, but also takes the inclination data into account. Specifically, the preset adjustment algorithm is a multi-degree-of-freedom control algorithm, which can calculate the offset amount by using the existing deviation analysis algorithm and convert it into the execution amount of the corresponding motor to achieve it, and it can handle both planar position deviation (X, Y) and angular deviation (e.g., pitch angle, yaw angle). The bonder can be equipped with a multi-axis motion platform, which can simultaneously perform translation in the X, Y, and Z directions and rotation in the pitch and yaw directions according to the comprehensive adjustment amount calculated by the algorithm, thereby achieving accurate alignment of the chip and wafer in space.

[0084] Through the above design, the method of the present application solves the problem of the inclination (angle deviation) between the chip and the wafer in addition to the plane coordinate deviation in the chip bonding process, avoids the situation that the best bonding quality and yield cannot be achieved due to the correction of only the plane position and the neglect of the inclination, and improves the alignment accuracy and ensures the bonding quality and yield by introducing the collimation assembly 8 and the inclination measurement step, so that the system can fully master the deviation of the sample in the plane and the space, and adjust the position of the chip and / or the wafer according to the coordinate deviation, the inclination and the preset adjustment algorithm.

[0085] In the description of the present specification, the description referring to the terms "one embodiment", "certain embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples.

[0086] The above only describes some embodiments of the present application. For those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application.

Claims

1. An optical alignment device for chip bonding, used to simultaneously obtain the positions of a wafer and a chip for alignment and bonding, characterized in that: The device comprises: a DUV laser, a first lens group, a second lens group, an internal bidirectional reflection prism, a first DUV objective lens, a second DUV objective lens and an imaging component; The DUV laser output end transmits the laser light to the first mirror group and the second mirror group respectively through two light-guiding optical fibers; The first DUV objective lens and the second DUV objective lens are respectively arranged on both sides of the internal bidirectional reflection prism and face opposite directions; The internal bidirectional reflection prism is used to reflect the laser light output by the first lens group and the second lens group to the first DUV objective lens and the second DUV objective lens respectively so as to project the laser light onto the sample; The internal bidirectional reflection prism is further used to reflect the sample light received by the first DUV objective lens and the second DUV objective lens to the first lens group and the second lens group respectively, so that the first lens group and the second lens group reflect the sample light into the imaging assembly; The first lens group and the second lens group each include a fiber-coupled collimator, a first reflecting prism, a lens group, and a first beam splitter prism, which are sequentially arranged according to the direction of laser transmission, wherein the first beam splitter prism is used to output the laser to the internal bidirectional reflection prism and to reflect the sample light into the imaging assembly; The device also includes a collimating assembly, and the first lens group and the second lens group also include a second beam splitter prism arranged between the first reflecting prism and the lens group, and the second beam splitter prism is also used to reflect the light portion of the sample light passing through the first beam splitter prism and the lens group to the collimating assembly.

2. The optical alignment device for chip bonding according to claim 1, wherein: The collimating assembly includes a third beam splitter prism, a relay lens group and a collimator camera which are sequentially arranged along the light transmission direction.

3. The optical alignment device for chip bonding according to claim 1, wherein: The first lens group and the second lens group are symmetrically arranged on both sides of the internal bidirectional reflection prism.

4. The optical alignment device for chip bonding according to claim 1, wherein: The imaging component includes a low-pass filter, an imaging tube lens and a DUV area array camera which are arranged in sequence according to the transmission direction of the sample light.

5. The optical alignment device for chip bonding according to claim 4, wherein: The imaging assembly also includes: a double-sided reflecting prism and two second reflecting prisms, the two second reflecting prisms are respectively used to reflect the sample light reflected by the first lens group and the second lens group to the two reflecting surfaces of the double-sided reflecting prism, so that the double-sided reflecting prism reflects the two sample lights in parallel to the low-pass filter.

6. The optical alignment device for chip bonding according to claim 4, wherein: The DUV area array camera is divided into imaging areas for receiving two sample lights for imaging.

7. The optical alignment device for chip bonding according to claim 1, wherein: The first DUV objective lens and the second DUV objective lens are symmetrically arranged on upper and lower sides of the internal bidirectional reflection prism.

8. An alignment method for an optical alignment device for chip bonding according to any one of claims 1 to 7, characterized in that: The optical alignment device for chip bonding is installed in a bonding machine, and the first DUV objective lens and the second DUV objective lens are respectively used to collect sample light of the chip as a sample upward and to collect sample light of the wafer as a sample downward; The alignment method comprises the following steps: S1. Using the imaging component, simultaneously collect image data containing alignment marks on the chip and the wafer; S2. Analyze the alignment marks in the image data to locate the positions of the chip and the wafer, and calculate the coordinate deviation between the two, so that the bonding machine adjusts the position of the chip and / or wafer according to the coordinate deviation.

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