Flip chip offset measurement system and method

Abstract

The embodiment of the application provides a flip chip offset measurement system and a measurement method, the measurement system comprises a first light source and a second light source with different wavelengths of outgoing light beams, an imaging assembly and a processing assembly, the first light source is controlled to emit a first light beam to penetrate the flip chip and irradiate a first target in a deep layer, and a first image containing the first target is acquired from a first detector; the second light source is controlled to emit a second light beam to irradiate a second target on the surface of the flip chip, and a second image containing the second target is acquired from a second detector, finally, the processing assembly acquires a first offset and a second offset of the flip chip relative to the substrate based on the first image and the second image, and obtains a bonding offset of the flip chip according to the first offset and the second offset. The application adopts a dual-wavelength light source to irradiate the flip chip in time sharing and wave band sharing, breaks through the penetration-reflectivity contradiction of single-wavelength detection, and improves the accuracy and reliability of the bonding offset detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor packaging, in particular to a flip chip offset measurement system and a measurement method. BACKGROUND

[0002] Flip chip bonding is an advanced integrated circuit packaging technology, which directly connects the electrical connection surface (usually bump or solder ball array) of the chip with the substrate (such as PCB, ceramic substrate or silicon interposer) through soldering, conductive adhesive or other means to realize electrical and mechanical connection. Unlike traditional wire bonding, flip chip directly connects with the substrate through the bumps on the bottom of the chip, eliminating the traditional wire bonding step, with shorter interconnection path, higher I / O density and better electrical performance. It is widely used in high-performance computing, mobile devices, automotive electronics and other fields.

[0003] For flip chip bonding process, while realizing the electrical connection between wafers, the precision requirement of wafer bonding is very high. The uniformity and consistency of bonding offset can provide reliable bonding quality and reliable electrical connection between upper and lower wafers. However, the current chip bonding offset detection technology cannot simultaneously cover the alignment requirements of chip surface and internal structure, resulting in low offset detection precision. SUMMARY

[0004] The present application provides a flip chip offset measurement system and a measurement method, which can solve the technical problem of low offset detection precision in the current chip bonding offset detection.

[0005] In a first aspect, the present application provides a flip chip offset measurement system, the flip chip is used for bonding on a substrate, and the inside and surface of the flip chip are respectively provided with a first target and a second target. The offset measurement system comprises:

[0006] A light source assembly comprising a first light source and a second light source; the first light source is used to emit a first light beam to penetrate the flip chip and irradiate the first target at a deep layer, and the second light source is used to emit a second light beam to irradiate the second target on the surface of the flip chip; wherein the wavelengths of the first light beam and the second light beam emitted by the first light source and the second light source are different;

[0007] An imaging assembly is used to collect a first image formed by the reflection of the first light beam on the first target, and a second image formed by the reflection of the second light beam on the second target;

[0008] The processing component is configured to acquire a first offset of the flip chip relative to the substrate based on the first image, acquire a second offset of the flip chip relative to the substrate based on the second image, and obtain a bonding offset of the flip chip according to the first offset and the second offset.

[0009] In some embodiments, the imaging component includes a first detector and a second detector; the first detector is configured to collect first signal light generated by reflection of the first light beam on the first target and form a first image; and the second detector is configured to collect second signal light generated by reflection of the second light beam on the second target and form a second image.

[0010] In some embodiments, the offset measurement system of the flip chip further includes an optical component.

[0011] The optical component includes a plurality of optical elements and an objective lens; the plurality of optical elements are configured to form a coaxial transmission optical path of the first light beam and the second light beam, so that the first light beam is incident on the first target via the objective lens, or the second light beam is incident on the second target via the objective lens.

[0012] The plurality of optical elements are further configured to form a coaxial transmission optical path of the first signal light and the second signal light, so that the first signal light is transmitted to the first detector via the objective lens, or the second signal light is transmitted to the second detector via the objective lens.

[0013] In some embodiments, the first light beam and the second light beam are incident on the objective lens at different times.

[0014] In some embodiments, the optical component includes at least a first optical element, a third optical element, and a fourth optical element, which are combined to form the coaxial transmission optical path of the first light beam and the second light beam; the first light beam emitted by the first light source is reflected by the first optical element and the third optical element in sequence and then is incident on the objective lens, so that the first light beam is incident on the first target via the objective lens; the second light beam emitted by the second light source is reflected by the fourth optical element and the third optical element in sequence and then is incident on the objective lens, so that the second light beam is incident on the second target via the objective lens.

[0015] The optical assembly further comprises a fifth optical element and a sixth optical element, which cooperate with the third optical element to form a coaxial transmission light path of the first signal light and the second signal light; the first signal light reflected by the first target is received by the objective lens, and then transmitted to the first detector after being transmitted by the third optical element and then being transmitted or reflected by the fifth optical element; the second signal light reflected by the second target is received by the objective lens, and then transmitted to the second detector after being transmitted by the third optical element and then being reflected or transmitted by the fifth optical element.

[0016] In some embodiments, the optical assembly further comprises a second optical element and / or a sixth optical element;

[0017] The second optical element is configured to reflect the first light beam reflected by the first optical element and the second light beam reflected by the fourth optical element; and the sixth optical element is configured to reflect the first light beam or the second light beam reflected by the fifth optical element.

[0018] In some embodiments, the first optical element, the fourth optical element and the second optical element are coaxially arranged, and the third optical element and the fifth optical element are coaxially arranged; the fourth optical element is further configured to transmit the first light beam.

[0019] In some embodiments, the first optical element, the second optical element and the sixth optical element are mirrors; the third optical element is a half-transmission half-reflection mirror; and the fourth optical element and the fifth optical element are long-wave dichroic beam splitters or short-wave dichroic beam splitters.

[0020] In some embodiments, the optical assembly comprises at least a first optical element, a second optical element, a third optical element and a fourth optical element, which are combined to form a coaxial transmission light path of the first light beam and the second light beam; the first light beam emitted by the first light source is reflected by the first optical element, the second optical element and the third optical element in sequence, and then is incident on the objective lens to irradiate the first target through the objective lens; the second light beam emitted by the second light source is reflected by the fourth optical element, the second optical element and the third optical element in sequence, and then is incident on the objective lens to irradiate the second target through the objective lens.

[0021] The optical assembly further comprises a fifth optical element and a sixth optical element, which cooperate with the third optical element to form a coaxial transmission light path of the first signal light and the second signal light; the first signal light reflected by the first target is received by the objective lens, and is transmitted to the first detector after being projected by the third optical element and reflected by the fifth optical element and the sixth optical element in sequence; the second signal light generated after being reflected by the second target is received by the objective lens, and is transmitted to the second detector after being transmitted by the third optical element and the fifth optical element in sequence.

[0022] In some embodiments, the first optical element, the fourth optical element and the second optical element are coaxially arranged, and the third optical element and the fifth optical element are coaxially arranged; the fourth optical element is further used for transmitting the first light beam.

[0023] The first optical element, the second optical element and the sixth optical element are mirrors; the third optical element is a half-transmission half-reflection mirror; the fourth optical element is a long-wave dichroic beam splitter, and the fifth optical element is a short-wave dichroic beam splitter.

[0024] In some embodiments, the included angle between the reflecting surface of each of the first optical element, the second optical element, the third optical element, the fourth optical element, the fifth optical element and the sixth optical element and the normal line thereof is 45°.

[0025] In some embodiments, the first light source is an infrared light source, and the second light source is a visible light source; the first detector is an infrared light camera, and the second detector is a visible light camera.

[0026] In some embodiments, the light source assembly further comprises a first modulation unit for modulating the first light beam and a second modulation unit for modulating the second light beam; the imaging assembly further comprises a third modulation unit for modulating the first signal light and a fourth modulation unit for modulating the second signal light.

[0027] In some embodiments, a long-wave band-pass filter is arranged in front of the first detector, and a short-wave band-pass filter is arranged in front of the second detector.

[0028] In a second aspect, the embodiments of the present application provide a method for measuring an offset of a flip chip, the flip chip is used to be attached on a substrate, and a first target and a second target are respectively arranged in the interior and the surface of the flip chip, and the first target and the second target are located on the same side of the flip chip.

[0029] The method for measuring the offset comprises:

[0030] controlling a first light source to emit a first light beam to penetrate the flip chip and irradiate a first target at a deep layer, and obtaining a first image containing the first target from a first detector;

[0031] controlling a second light source to emit a second light beam to irradiate a second target on a surface of the flip chip, and obtaining a second image containing the second target from a second detector; wherein the first light source is an infrared light source, and the second light source is a visible light source;

[0032] obtaining a first offset of the flip chip relative to the substrate based on the first image, and obtaining a second offset of the flip chip relative to the substrate based on the second image;

[0033] obtaining a fitting offset of the flip chip according to the first offset and the second offset.

[0034] In some embodiments, the obtaining the first offset of the flip chip relative to the substrate based on the first image comprises:

[0035] performing morphological denoising on the first image;

[0036] determining a best matching position of the denoised first image and a predefined template according to the predefined template, wherein the predefined template comprises at least one sub-image having a same shape or pattern as the first target;

[0037] determining a first coordinate of the first target based on the best matching position;

[0038] determining the first offset of the flip chip relative to the substrate according to the first coordinate.

[0039] In some embodiments, the determining the best matching position of the denoised first image and the predefined template according to the predefined template comprises:

[0040] sliding the predefined template and comparing the denoised first image with the predefined template pixel by pixel;

[0041] calculating a similarity of the denoised first image and a sub-image on the predefined template;

[0042] taking a position with a highest similarity as the best matching position of the denoised first image and the predefined template.

[0043] In some embodiments, the obtaining the second offset of the flip chip relative to the substrate based on the second image comprises:

[0044] performing sub-pixel edge detection on the second image to obtain a pixel gray scale distribution of the second image;

[0045] determine a second coordinate of the second target based on a pixel grayscale distribution of the second image;

[0046] determine a second offset of the flip chip relative to the substrate according to the second coordinate.

[0047] In some embodiments, the offset measurement method of the flip chip according to any embodiment of the second aspect is applied to the offset measurement system of the flip chip according to any embodiment of the first aspect.

[0048] The offset measurement system and method of the flip chip provided by the embodiments of the present application can realize the measurement of the offset of the flip chip by using a dual-wavelength light source to irradiate the flip chip in time division and by waveband, that is, using long-wave light to penetrate the chip material and directly reach the deep first target, and using short-wave light to irradiate the surface second target with high reflectivity, and then using the imaging assembly to collect the double-layer reflection images in different channels, and using the processing assembly to comprehensively analyze the deep and surface offsets by using a multi-modal data fusion algorithm, so as to realize the measurement of the offset of the flip chip. The present application effectively solves the technical limitations that the traditional short-wavelength light cannot reach the internal mark of the chip and the long-wavelength light has low reflectivity on the surface mark, breaks through the penetration-reflectivity contradiction of single-wavelength detection, realizes the high-precision three-dimensional measurement of the offset of the chip-substrate bonding, and significantly improves the accuracy, reliability and anti-interference ability of the offset detection, thereby providing a more comprehensive quality control means for the high-density packaging process. BRIEF DESCRIPTION OF DRAWINGS

[0049] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.

[0050] Figure 1 FIG. 1 is a schematic diagram of a flip-chip packaged chip structure;

[0051] Figure 2 FIG. 2 is a schematic diagram of an offset measurement system of a flip chip according to an embodiment of the present application;

[0052] Figure 3 FIG. 3 is a schematic diagram of an offset measurement system of a flip chip according to another embodiment of the present application;

[0053] Figure 4 FIG. 4 is a schematic diagram of an optical assembly according to an embodiment of the present application;

[0054] Figure 5 FIG. 5 is a schematic diagram of an optical assembly according to another embodiment of the present application;

[0055] Figure 6 FIG. 6 is a schematic diagram of an offset measurement system of a flip chip according to another embodiment of the present application;

[0056] Figure 7 A flow chart of a method for measuring the offset of a flip chip according to one embodiment of the present application is provided.

[0057] Figure 8 A flow chart of a method for measuring the offset of a flip chip according to another embodiment of the present application is provided.

[0058] Figure 9 A flow chart of a method for measuring the offset of a flip chip according to yet another embodiment of the present application is provided.

[0059] The specific embodiments of the present application have been shown by way of example in the above figures and will be described in more detail below. These figures and this written description are not intended to limit the scope of the present application in any way, but rather to illustrate various embodiments of the application to a person of ordinary skill in the art. DETAILED DESCRIPTION

[0060] The present application will be described in further detail by way of specific embodiments with reference to the attached drawings. In the following embodiments, like elements are denoted by like reference numerals. In the following embodiments, many specific details are described in order to provide a thorough understanding of the present application. However, it will be apparent to one of ordinary skill in the art that the present application can be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to unnecessarily obscure aspects of the present application. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "connected" and "coupled" and variations thereof are used broadly and encompass both direct and indirect connections and couplings.

[0061] In addition, various features which have been described in the specification in association with the description of embodiments can be possible to combine in any suitable manner. Also, the order of the steps or actions in the methods described in the specification can be changed or adjusted as long as it is apparent to a person of ordinary skill in the art that the steps or actions can be performed in the changed or adjusted order. Therefore, the various sequences in the specification and the attached drawings are merely for the purpose of clear description of one embodiment and do not mean that the sequence is necessary unless otherwise specified or limited.

[0062] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of a kind and do not limit the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and " / " generally means that the front and rear associated objects are in an "or" relationship. The present application refers to "connection" and "coupling", unless otherwise specified, including direct and indirect connection (coupling).

[0063] Flip chip bonding process is a high-density, high-performance semiconductor packaging technology, by inverting the active surface of the chip directly and bonding to the substrate, using solder bumps to achieve electrical connection and mechanical fixation. In the flip chip bonding process, wafer height consistency is the core prerequisite to ensure the bonding quality. Ideally, all solder bump heights are consistent, and the bonding simultaneously contacts the substrate, forming uniform solder joints. If there is height difference on the wafer surface (such as uneven bump height, wafer warping), the high bump contacts the substrate in advance during bonding, and the substrate bears excessive pressure, which may cause solder extrusion and short circuit. The low bump does not fully contact the substrate, which may result in false soldering and open circuit, ultimately affecting device reliability and yield.

[0064] It should be noted that the current flip chip bonding offset detection technology often uses a single detection method, which results in low offset detection accuracy. For example, visible light imaging technology is used for offset detection, but since there is a silicon layer or metal layer outside the bonding part of the chip and substrate, visible light cannot penetrate the silicon layer or metal layer, and can only identify the chip surface markers, cannot penetrate the silicon layer to detect internal or back markers, and cannot meet the requirements of multi-layer chip packaging and bonding alignment. For example, infrared imaging technology is used for offset detection. Although infrared light (wavelength > 1100 nm) can penetrate the silicon layer, the reflectivity of the chip surface metal markers is low, and the imaging resolution is limited by the infrared sensor pixel size (usually > 5 μm) and target size, which cannot meet the requirements. The technical solution of the present application can overcome the problem of low detection accuracy of the prior art, and use a set of optical structures to realize the alignment of the chip surface and internal structure, improving the offset detection accuracy.

[0065] Figure 1 A schematic diagram of a flip-chip packaged chip structure is shown in FIG. 1. Figure 1As shown, the flip-chip includes a plurality of micro-grain units, adjacent micro-grain units are electrically isolated by heat-conducting channels filled with high-thermal-conductivity insulating ceramic, each micro-grain unit includes a sapphire substrate 1, an N-type nitride layer 2, a light-emitting layer 3, a P-type nitride layer 4, a reflecting layer 5, a P-type electrode 10, an N-type electrode 9 and a passivation layer 8 grown on the sapphire substrate 1 in sequence, the micro-grain units are connected in series or / and parallel by metal wires on the substrate 12; the N-type electrode 9 is composed of a thin cuboid structure above the substrate 12 and a zigzag long strip structure penetrating through the reflecting layer 5, the P-type nitride layer 4 and the light-emitting layer 3 to connect to the N-type nitride layer 2, the zigzag long strip structure when viewed from above the N-type electrode and the comb-shaped structure when viewed from the section of the N-type electrode; the N-type electrode 9 is electrically isolated from the reflecting layer 5, the P-type nitride layer 4, the light-emitting layer 3 and the P-type electrode 10 by the passivation layer 8, the N-type electrode 9 is connected to the N-type nitride layer 2, and the P-type electrode 10 is connected to the P-type nitride layer 4 through the reflecting layer 5. The high-thermal-conductivity insulating ceramic is a ceramic material with high thermal conductivity such as aluminum nitride (AlN) ceramic or silicon carbide (SiC) ceramic.

[0066] Based on the foregoing, while realizing the electrical connection between wafers, the precision requirement of wafer bonding is very high, and before flip-chip bonding and packaging, the offset of the flip-chip needs to be measured to ensure the uniformity and consistency of the bonding offset during packaging. Figure 1 As shown, there is a silicon layer or a metal layer outside the bonding part of the chip and the substrate, the traditional offset detection is realized by using visible light imaging technology, but visible light cannot penetrate the silicon layer or the metal layer, and can only identify the chip surface marker, cannot penetrate the silicon layer to detect internal or back markers, and cannot meet the requirements of multi-layer chip packaging and bonding alignment; another is to use infrared imaging technology, although infrared light can penetrate the silicon layer, the reflectivity of the metal marker on the chip surface is low, and the imaging resolution is also limited by the pixel size and target size of the infrared sensor, which cannot meet the requirements.

[0067] The present application proposes a flip-chip offset measurement system and method, which combines the imaging advantages of infrared and visible light, realizes the synchronous or time-sharing identification of the chip surface and internal markers, and realizes the accurate measurement of the offset of the flip-chip.

[0068] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes may not be described in detail in some examples. The embodiments of the present application will be described below with reference to the drawings.

[0069] Figure 2 The structure schematic diagram of the flip-chip offset measurement system provided by an embodiment of the present application is shown in the figure. Figure 2As shown, the flip-chip offset measurement system provided by the embodiment is used for measuring the offset of the flip-chip, the flip-chip is used for being attached on the substrate, and the inside and surface of the flip-chip are respectively provided with the first target and the second target. The flip-chip offset measurement system at least includes a light source assembly, an imaging assembly and a processing assembly 230.

[0070] In the embodiment, the light source assembly includes a first light source 2101 and a second light source 2102, wherein the first light source 2101 is used for emitting a first light beam to penetrate the flip-chip and irradiate the first target in the deep layer, and the second light source 2102 is used for emitting a second light beam to irradiate the second target on the surface of the flip-chip; wherein the first light beam and the second light beam emitted by the first light source 2101 and the second light source 2102 are different in wavelength. That is, the first light beam emitted by the first light source 2101 can penetrate the silicon layer or the metal layer existing outside the attachment part of the chip and the substrate, and reach the first target arranged in the deep layer of the flip-chip, and the second light beam emitted by the second light source 2102 can irradiate the second target arranged on the surface of the flip-chip. At the same time, it is considered that the first light beam has good reflectivity after penetrating the silicon layer or the metal layer, and the second light beam only needs to have good reflectivity to the second target arranged on the surface, therefore, the first light beam and the second light beam emitted by the first light source 2101 and the second light source 2102 are different in wavelength.

[0071] In some embodiments, the first light source 2101 can be infrared light, X-ray or gamma ray, which can penetrate the metal layer or the silicon layer outside the chip. In practice, considering that the X-ray and the gamma ray will have a physical reaction when irradiating the memory chip, which may cause the electrical failure of the memory chip, and have a certain radiation and high cost, they are not considered as the optimal choice. The second light source 2102 adopts visible light which has high reflectivity to the metal mark on the surface of the chip, and has low cost, which is considered as the optimal choice.

[0072] In the embodiment, the imaging assembly is arranged on the reflected light path of the first light beam reflected by the first target and the reflected light path of the second light beam reflected by the second target, and is used for collecting the first image formed by the first light beam reflected by the first target and the second image formed by the second light beam reflected by the second target, which will be used as the basis for calculating the offset of the flip-chip.

[0073] In some embodiments, the imaging assembly includes a first detector 2201 and a second detector 2202, wherein the first detector 2201 is used for collecting the first signal light generated by the first light beam reflected by the first target and forming the first image, and the second detector 2202 is used for collecting the second signal light generated by the second light beam reflected by the second target and forming the second image.

[0074] In some embodiments, the first detector 2201 and the second detector 2202 are photoelectric detectors, CCD cameras or CMOS sensors. Considering that the first detector 2201 is used to capture the first signal light reflected by the first light beam, and the second detector 2202 is used to capture the second signal light reflected by the second light beam, the spectral response characteristics of the first detector 2201 cover the wavelength band of the first light beam emitted by the first light source 2101. Similarly, the spectral response characteristics of the second detector 2202 cover the wavelength band of the second light beam emitted by the second light source 2102.

[0075] In some embodiments, when the first light source 2101 is an infrared light source, the first detector 2201 is an infrared light camera, and when the second light source 2102 is a visible light source, the second detector 2202 is a visible light camera.

[0076] In this embodiment, the processing component 230 is configured to obtain a first offset of the flip-chip relative to the substrate based on the first image, obtain a second offset of the flip-chip relative to the substrate based on the second image, and obtain a bonding offset of the flip-chip based on the first offset and the second offset.

[0077] It can be understood that the processing component 230 is configured to receive the first image and the second image transmitted by the first detector 2201 and the second detector 2202, and obtain the first offset of the first target relative to the substrate based on the first target information carried by the first image and the second offset of the second target relative to the substrate based on the second target information carried by the second image, and further obtain the bonding offset of the flip-chip relative to the substrate based on the first offset and the second offset.

[0078] In summary, the offset measurement system of the flip-chip provided in this embodiment uses a dual-wavelength light source to irradiate the flip-chip in time and by wavelength, that is, a long-wavelength light is used to penetrate the chip material and reach the deep first target, and a short-wavelength light is used to irradiate the surface second target with high reflectivity. After the imaging assembly collects the double-layer reflection images in different channels, the processing component comprehensively analyzes the deep and surface offsets by using a multi-modal data fusion algorithm, so as to realize the measurement of the bonding offset of the flip-chip. This measurement system effectively solves the technical limitations of the traditional short-wavelength light that cannot reach the internal mark of the chip and the long-wavelength light that causes imaging blur due to low reflectivity of the surface mark, breaks through the penetration-reflectivity contradiction of single-wavelength detection, and realizes high-precision three-dimensional measurement of the chip-substrate bonding offset, thereby significantly improving the accuracy, reliability and anti-interference ability of the bonding offset detection, and providing a more comprehensive quality control means for high-density packaging process.

[0079] Figure 3 FIG. 1 shows a structure schematic diagram of an offset measurement system of a flip-chip according to another embodiment of the present application. As shown in FIG. 1, the offset measurement system of the flip-chip comprises a first light source 2101, a second light source 2102, a first detector 2201, a second detector 2202, an imaging component 230 and a processing component 240.Figure 3 As shown, the flip chip offset measurement system provided in this embodiment, based on any of the above embodiments, includes an optical component 240 in addition to the light source component, imaging component, and processing component 230.

[0080] In this embodiment, the optical component 240 includes a plurality of optical elements and an objective lens 2407, which are used to form a transmission optical path for the first beam and the second beam. Specifically, the plurality of optical elements are used to form a coaxial transmission optical path for the first beam and the second beam, so that the first beam illuminates the first target through the objective lens 2407, or the second beam illuminates the second target through the objective lens 2407; and to form a coaxial transmission optical path for the first signal light and the second signal light, so that the first signal light is transmitted to the first detector 2201 through the objective lens 2407, or the second signal light is transmitted to the second detector 2202 through the objective lens 2407.

[0081] In some embodiments, when the optical assembly 240 includes only one objective lens 2407, the first beam and the second beam are incident on the objective lens 2407 in a time-division manner.

[0082] Understandably, the time-division multiplexing of the first and second beams into objective lens 2407 effectively avoids signal aliasing caused by interference, scattering, or detector nonlinearity when beams of different wavelengths or polarization states are simultaneously incident. Simultaneously, it simplifies system complexity, reduces the requirements for detector bandwidth and dynamic range, and enables synchronous multi-parameter measurements in dynamic scenarios. Therefore, eliminating crosstalk and interference between the first and second beams through time isolation improves the signal-to-noise ratio, dynamic range, and measurement accuracy of the imaging system, ultimately leading to higher resolution and lower noise imaging results.

[0083] Figure 4 This is a schematic diagram of the structure of an optical component provided in one embodiment of this application. Figure 4 As shown, the optical component 240 provided in this embodiment includes at least a first optical element 2401, a second optical element 2402, a third optical element 2403, a fourth optical element 2404, a fifth optical element 2405, and a sixth optical element 2406.

[0084] Specifically, the first optical element 2401, the second optical element 2402, the third optical element 2403, and the fourth optical element 2404 combine to form a coaxial transmission optical path of the first light beam and the second light beam. The first light beam emitted by the first light source 2101 is reflected by the first optical element 2401, the second optical element 2402, and the third optical element 2403 in turn and then enters the objective lens 2407 to irradiate the first target through the objective lens 2407; the second light beam emitted by the second light source 2102 is reflected by the fourth optical element 2404, the second optical element 2402, and the third optical element 2403 in turn and then enters the objective lens 2407 to irradiate the second target through the objective lens 2407.

[0085] The fifth optical element 2405 and the sixth optical element 2406 cooperate with the third optical element 2403 to form a coaxial transmission optical path of the first signal light and the second signal light; the first signal light generated by reflection of the first target is received by the objective lens 2407 and then transmitted to the first detector 2201 by transmission of the third optical element 2403 and the fifth optical element 2405 in turn; the second signal light generated by reflection of the second target is received by the objective lens 2407 and then transmitted to the second detector 2202 by transmission of the third optical element 2403, reflection of the fifth optical element 2405, and reflection of the sixth optical element 2406 in turn.

[0086] It should be noted that the second optical element 2402 and the sixth optical element 2406 are arranged to enable the light rays that originally need to extend in a straight line for a long distance to reach the target position to be reflected by the reflector and then travel at a specific angle, thereby effectively folding the optical path structure without changing the optical performance of the light rays, optimizing the layout of the optical path, and helping to reduce the overall physical size of the system or adapt to specific space installation restrictions to achieve efficient transmission of optical signals in limited space. Therefore, in the optical path layout different from the above-mentioned embodiments, the second optical element 2402 and the sixth optical element 2406 can also be selected not to be arranged.

[0087] In some embodiments, to further shorten the path of the light beam transmission and meet the coaxial transmission of the first light beam and the second light beam, the first optical element 2401, the fourth optical element 2404, and the second optical element 2402 are arranged coaxially in the vertical direction, and the third optical element 2403 and the fifth optical element 2405 are arranged coaxially in the vertical direction. At this time, for the first light beam, the fourth optical element 2404 is further used to receive the first light beam reflected by the first optical element 2401 and transmit it to the second optical element 2402.

[0088] In some embodiments, the first optical element 2401 and the sixth optical element 2406 are arranged coaxially in the horizontal direction.

[0089] In some embodiments, the first optical element 2401, the second optical element 2402, and the sixth optical element 2406 are mirrors; the third optical element 2403 is a half-mirror; the fourth optical element 2404 and the fifth optical element 2405 are long-wave dichroic mirrors, i.e., the fourth optical element 2404 and the fifth optical element 2405 can transmit the first light beam with a longer wavelength and reflect the second light beam with a shorter wavelength.

[0090] Figure 5 The structural schematic diagram of an optical assembly provided by another embodiment of the present application is shown in FIG. 2B. As shown in FIG. 2B, the optical assembly 240 provided by the embodiment includes at least a first optical element 2401, a second optical element 2402, a third optical element 2403, a fourth optical element 2404, a fifth optical element 2405, and a sixth optical element 2406. Figure 5

[0091] Specifically, the first optical element 2401, the second optical element 2402, the third optical element 2403, and the fourth optical element 2404 are combined to form a coaxial transmission optical path of the first light beam and the second light beam; the first light beam emitted by the first light source 2101 is sequentially reflected by the first optical element 2401, the second optical element 2402, and the third optical element 2403, and then is incident on the objective lens 2407 to irradiate the first target through the objective lens 2407; the second light beam emitted by the second light source 2102 is sequentially reflected by the fourth optical element 2404, the second optical element 2402, and the third optical element 2403, and then is incident on the objective lens 2407 to irradiate the second target through the objective lens 2407.

[0092] The fifth optical element 2405 and the sixth optical element 2406 are combined with the third optical element 2403 to form a coaxial transmission optical path of the first signal light and the second signal light; the first signal light generated by reflection of the first target is received by the objective lens 2407, and then is transmitted to the first detector 2201 after being sequentially projected by the third optical element 2403 and reflected by the fifth optical element 2405 and the sixth optical element 2406; the second signal light generated by reflection of the second target is received by the objective lens 2407, and then is transmitted to the second detector 2202 after being sequentially transmitted by the third optical element 2403 and the fifth optical element 2405.

[0093] As described above, in an optical path layout different from the embodiment, the second optical element 2402 and the sixth optical element 2406 can also be selected not to be arranged.

[0094] ​In some embodiments, to shorten the beam transmission path and satisfy the coaxial transmission of the first and second beams, the first optical element 2401, the fourth optical element 2404, and the second optical element 2402 are coaxially arranged in the vertical direction, and the third optical element 2403 and the fifth optical element 2405 are coaxially arranged in the vertical direction. In this case, for the first beam, the fourth optical element 2404 is also used to receive the first beam reflected by the first optical element 2401 and transmit it to the second optical element 2402.

[0095] In some embodiments, the first optical element 2401 and the sixth optical element 2406 are arranged coaxially in the horizontal direction.

[0096] In some embodiments, the first optical element 2401, the second optical element 2402, and the sixth optical element 2406 are mirrors; the third optical element 2403 is a semi-transparent mirror; the fourth optical element 2404 is a long-wavelength dichroic beam splitter; and the fifth optical element 2405 is a short-wavelength dichroic beam splitter.

[0097] Figure 5 The optical component 240 shown is similar to the one described in the above embodiment ( Figure 4 The difference (as shown) is that the fourth optical element 2404 is configured as a long-wavelength dichroic beam splitter, that is, the fourth optical element 2404 can transmit a first beam with a longer wavelength and reflect a second beam with a shorter wavelength. The fifth optical element 2405 is configured as a short-wavelength dichroic beam splitter, that is, the fifth optical element 2405 can reflect a first beam with a longer wavelength and transmit a second beam with a shorter wavelength.

[0098] In some embodiments, based on the structure of the optical component 240 in any of the above embodiments, the angle between the reflecting surface of the first optical element 2401, the second optical element 2402, the third optical element 2403, the fourth optical element 2404, the fifth optical element 2405 and the sixth optical element 2406 and their own normal is 45°, so as to realize the coaxial transmission of the first beam and the second beam. It can also utilize the symmetry of the specular reflection or the beam splitter to separate the incident light and the reflected light path by 90 degrees, thereby simplifying the system structure and reducing space occupation. It can also balance the reflection / transmission efficiency of the beam splitter, and finally achieve compact, stable and multifunctional optical path control.

[0099] Figure 6 This is a schematic diagram of the structure of a flip-chip offset measurement system provided in another embodiment of this application. Figure 6 As shown, the offset measurement system for flip-chip provided in this embodiment, based on any of the above embodiments, further includes a modulation unit and a filtering unit for modulating the first beam and the second beam.

[0100] In some embodiments, the light source assembly includes a first modulation unit 2103 for modulating the first light beam and a second modulation unit 2104 for modulating the second light beam.

[0101] The first modulation unit 2103 and the second modulation unit 2104 are respectively arranged on the light path of the first light source 2101 and the light path of the second light source 2102, and are used to dynamically adjust the first light beam and the second light beam, including intensity modulation, phase modulation, wavelength / frequency modulation and / or polarization state modulation of the light beam, to realize encoding, modulation or wavelength control of the first light beam and the second light beam, to provide customized light input for the subsequent optical system, so that the first detector 2201 and the second detector 2202 can acquire clearer first and second images.

[0102] In some embodiments, the imaging assembly includes a third modulation unit 2203 for modulating the first signal light and a fourth modulation unit 2204 for modulating the second signal light.

[0103] The third modulation unit 2203 and the fourth modulation unit 2204 are respectively arranged in front of the first detector 2201 and the second detector 2202, and are used to dynamically adjust the characteristics of the first signal light and the second signal light before the light signal reaches the detector, including polarization control, phase compensation and light intensity equalization, to improve the imaging quality of the detector and suppress noise.

[0104] In some embodiments, a long-wave band-pass filter is arranged in front of the first detector 2201, and a short-wave band-pass filter is arranged in front of the second detector 2202, for selectively transmitting light signals of a specific wavelength range and suppressing interference of other wavelengths, thereby optimizing the signal-to-noise ratio of the detector and improving the performance of the system.

[0105] Figure 7 A flowchart of a flip-chip offset measurement method is provided for an embodiment of the present application. As shown in Figure 7 The flip-chip offset measurement method provided by the embodiment is used to measure a flip-chip that is used to be attached to a substrate and has a first target and a second target arranged inside and on the surface of the flip-chip, and the first target and the second target are located on the same side of the flip-chip. The offset measurement method specifically includes the following steps:

[0106] Step S710: control the first light source to emit a first light beam to penetrate the flip-chip and irradiate the first target at a deep layer, and acquire a first image containing the first target from the first detector.

[0107] Step S720: control the second light source to emit a second light beam to irradiate the second target on the surface of the flip-chip, and acquire a second image containing the second target from the second detector; wherein the first light source is an infrared light source, and the second light source is a visible light source.

[0108] It should be noted that in steps S710 and S720, controlling the first light source 2101 and the second light source 2102 to irradiate the flip chip can be performed in a time-division manner or simultaneously. Generally, time-division control of the first light source 2101 and the second light source 2102 is adopted. This can effectively avoid signal aliasing caused by interference, scattering, or detector response nonlinearity when beams of different wavelengths or polarization states are incident simultaneously, eliminate crosstalk and interference between the first beam and the second beam, improve the signal-to-noise ratio, dynamic range, and measurement accuracy of the imaging system, and ultimately achieve higher resolution and lower noise imaging results.

[0109] Step S730: Obtain the first offset of the flip chip relative to the substrate based on the first image, and obtain the second offset of the flip chip relative to the substrate based on the second image.

[0110] Step S740: Obtain the bonding offset of the flip chip based on the first offset and the second offset.

[0111] It is understood that this offset measurement method can be configured in the processing component 230 of the offset measurement system. This offset measurement system has at least a light source component and an imaging component. The light source component includes a first light source 2101 and a second light source 2102. The first light source 2101 is an infrared light source, and the second light source 2102 is a visible light source. That is, the first light beam emitted from the first light source 2101 can penetrate the silicon or metal layer outside the bonding area between the chip and the substrate, reaching the first target located deep within the flip chip. The first light beam emitted from the second light source 2102 can reach the second target on the chip surface. The imaging component includes a first detector 2201 and a second detector 2202. The first detector 2201 is used to collect the first signal light generated by the reflection of the first light beam from the first target and form a first image. The second detector 2202 is used to collect the second signal light generated by the reflection of the second light beam from the second target and form a second image.

[0112] After receiving the first image and the second image transmitted by the first detector 2201 and the second detector 2202, the processing component 230 of the offset measurement system can obtain the offset of the first target relative to the substrate, i.e. the first offset of the flip chip relative to the substrate, and the offset of the second target relative to the substrate, i.e. the second offset of the flip chip relative to the substrate, based on the first target information carried in the first image and the second target information carried in the second image. Furthermore, the bonding offset of the flip chip relative to the substrate can be obtained based on the first offset and the second offset.

[0113] The flip chip offset measurement method provided by the embodiment can improve the accuracy, reliability and anti-interference capability of the offset detection, and provides a more comprehensive quality control method for high-density packaging process.

[0114] Figure 8 The flowchart of the flip chip offset measurement method provided by another embodiment of the application is shown in FIG. 7. Figure 8 As shown in FIG. 7, based on the above embodiment, in step S730, the first offset of the flip chip relative to the substrate is obtained based on the first image, specifically including:

[0115] In step S810, the first image is morphologically denoised.

[0116] In step S820, the best matching position of the denoised first image and the predefined template is determined according to the predefined template, wherein the predefined template includes at least one sub-image with the same shape or pattern as the first target.

[0117] In some embodiments, the best matching position of the denoised first image and the predefined template is determined according to the predefined template, including:

[0118] In step S8201, the predefined template is slid and compared with the denoised first image pixel by pixel.

[0119] In step S8202, the similarity of the denoised first image and the sub-image on the predefined template is calculated.

[0120] In step S8203, the position with the highest similarity is taken as the best matching position of the denoised first image and the predefined template.

[0121] In step S830, the first coordinate of the first target is determined based on the best matching position.

[0122] In step S840, the first offset of the flip chip relative to the substrate is determined according to the first coordinate.

[0123] It can be understood that, before obtaining the first offset of the flip-chip relative to the substrate based on the first image, first, morphological denoising is performed on the first image, such as opening operation, closing operation, etc., to eliminate noise caused by small particles, scratches or uneven illumination on the surface of the chip, improve the image quality, and lay a foundation for subsequent accurate matching; then, based on a predefined template containing a sub-image with the same shape or pattern as the first target, the template and the denoised image are compared pixel by pixel through a sliding window, the similarity (such as normalized cross correlation NCC, structural similarity SSIM, etc.) between the two is calculated, and finally the region with the highest similarity is located as the best matching position, and then the first coordinate of the target in the image coordinate system is extracted; finally, based on the mapping relationship (which can be obtained through a coordinate conversion matrix) between the first coordinate of the target and the substrate reference coordinate system, the actual offset of the flip-chip relative to the substrate is calculated, such as X / Y direction displacement and rotation angle.

[0124] Figure 9 The flowchart of the offset measurement method of the flip-chip provided for another embodiment of the present application is shown in FIG. 9. Figure 9 As shown in FIG. 9, based on the above embodiment, in step S730, the second offset of the flip-chip relative to the substrate is obtained based on the second image, specifically including:

[0125] In step S910, sub-pixel edge detection is performed on the second image to obtain the pixel gray scale distribution of the second image.

[0126] In step S920, the second coordinate of the second target is determined based on the pixel gray scale distribution of the second image.

[0127] In step S930, the second offset of the flip-chip relative to the substrate is determined according to the second coordinate.

[0128] It can be understood that, before obtaining the first offset of the flip-chip relative to the substrate based on the first image, first, sub-pixel edge detection is performed on the second image, the gray scale gradient change of the pixel-level edge is analyzed, the edge positioning accuracy is improved to the sub-pixel level, in order to capture the subtle features of the target edge, and generate a high-precision pixel gray scale distribution map, to provide more detailed information for subsequent coordinate calculation; secondly, based on the gray scale distribution map, the center coordinate of the second target is determined by using a geometric fitting method (such as least squares fitting circle or straight line), and the second coordinate is converted into the actual physical offset of the flip-chip relative to the substrate.

[0129] In summary, by combining the first offset calculation method of morphological denoising and template matching, and the second offset calculation method based on sub-pixel edge detection and gray distribution fitting, the comprehensive performance of flip chip offset measurement can be significantly improved. The former ensures the robustness of target positioning by denoising and template matching, effectively suppressing the influence of image noise and local distortion on the measurement results; the latter uses sub-pixel edge detection to improve the positioning accuracy to the micron level, and further enhances the anti-interference ability based on the geometric fitting of gray distribution. The two methods work together to ensure the stability and repeatability of the measurement results, and achieve a balance between high precision and high efficiency. Finally, a reliable quality control method is provided for flip chip packaging process, which significantly reduces the yield loss caused by offset out-of-tolerance.

[0130] It should be noted that the offset measurement method of the flip chip provided by any of the above embodiments can be applied to the offset measurement system of the flip chip as described above. Figures 1-6 The offset measurement method of the flip chip provided by any of the above embodiments can be configured in the processing component 230 of the offset measurement system of the flip chip, and the steps of the offset measurement method of the flip chip provided by any of the above embodiments can be implemented by the processing component 230 or the processor in the processing component 230.

[0131] In some embodiments, the offset measurement method of the flip chip provided by any of the above embodiments can be configured in a computer storage medium or a computer program product, and the computer storage medium or the computer program product stores a program or instructions. The program or instructions are executed by the processor to implement the processes of any of the above offset measurement methods of the flip chip, and achieve the same technical effects. To avoid repetition, details are not repeated here.

[0132] The processor can be a central processing unit (CPU) or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application. The readable storage medium includes a computer readable storage medium, such as a computer readable only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0133] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the specific embodiments described above, and the specific embodiments described above are merely illustrative, but not restrictive, and a person of ordinary skill in the art can make several simple deductions, deformations or substitutions according to the idea of the present application without departing from the purpose of the present application and the scope protected by the claims, and the person of ordinary skill in the art can also make several simple deductions, deformations or substitutions according to the idea of the present application, which all belong to the protection of the present application.

Claims

1. A flip-chip offset measurement system, comprising: The flip chip is used to be attached on a substrate, and the inside and surface of the flip chip are respectively provided with a first target and a second target, and the offset measurement system comprises: A light source assembly comprising a first light source and a second light source; the first light source is used to emit a first light beam to penetrate the flip chip and irradiate the first target at a deep layer, and the second light source is used to emit a second light beam to irradiate the second target on the surface of the flip chip; wherein the first light beam and the second light beam emitted by the first light source and the second light source are different in wavelength; An imaging assembly for acquiring a first image formed by the first light beam reflected by the first target and a second image formed by the second light beam reflected by the second target; A processing assembly for obtaining a first offset of the flip chip relative to the substrate based on the first image, obtaining a second offset of the flip chip relative to the substrate based on the second image, and obtaining an attachment offset of the flip chip according to the first offset and the second offset.

2. The flip-chip offset measurement system of claim 1, wherein, The imaging assembly comprises a first detector and a second detector; the first detector is used to acquire first signal light generated by the first light beam reflected by the first target and form a first image; and the second detector is used to acquire second signal light generated by the second light beam reflected by the second target and form a second image.

3. The flip-chip offset measurement system of claim 2, wherein, Further comprising an optical assembly; The optical assembly comprises a plurality of optical elements and an objective lens; the plurality of optical elements are used to form a coaxial transmission light path of the first light beam and the second light beam, so that the first light beam irradiates the first target through the objective lens, or the second light beam irradiates the second target through the objective lens; The plurality of optical elements are also used to form a coaxial transmission light path of the first signal light and the second signal light, so that the first signal light is transmitted to the first detector through the objective lens, or the second signal light is transmitted to the second detector through the objective lens.

4. The flip-chip offset measurement system of claim 3, wherein, The first light beam and the second light beam are incident to the objective lens at different times.

5. The flip-chip offset measurement system of claim 3, wherein, The optical assembly at least comprises a first optical element, a third optical element and a fourth optical element, which are combined to form the coaxial transmission light path of the first light beam and the second light beam; the first light beam emitted by the first light source is reflected by the first optical element and the third optical element in sequence and then is incident to the objective lens, and irradiates the first target through the objective lens; The second light beam emitted by the second light source is reflected by the fourth optical element and the third optical element in sequence and then is incident to the objective lens, and irradiates the second target through the objective lens; The optical assembly further comprises a fifth optical element, which cooperates with the third optical element to form the coaxial transmission light path of the first signal light and the second signal light; the first signal light reflected by the first target is received by the objective lens, and then is transmitted to the first detector through the transmission of the third optical element and the transmission or reflection of the fifth optical element in sequence. The second signal light reflected by the second target is received by the objective lens, and then transmitted to the second detector after being transmitted by the third optical element and reflected or transmitted by the fifth optical element.

6. The flip-chip offset measurement system of claim 5, wherein, The optical assembly further comprises a second optical element and / or a sixth optical element; The second optical element is configured to reflect the first light beam reflected by the first optical element and the second light beam reflected by the fourth optical element; The sixth optical element is configured to reflect the first light beam or the second light beam reflected by the fifth optical element.

7. The flip-chip offset measurement system of claim 6, wherein, The first optical element, the fourth optical element and the second optical element are coaxially arranged, and the third optical element and the fifth optical element are coaxially arranged; the fourth optical element is further configured to transmit the first light beam. The first optical element, the second optical element and the sixth optical element are mirrors; the third optical element is a half-transmission half-reflection mirror; the fourth optical element and the fifth optical element are long-wave dichroic beam splitters or short-wave dichroic beam splitters.

8. The flip-chip offset measurement system of any of claims 5-7, wherein, The angle between the reflecting surface of each of the first optical element, the second optical element, the third optical element, the fourth optical element, the fifth optical element and the sixth optical element and the normal line thereof is 45°.

9. The flip-chip offset measurement system of claim 2, wherein, The first light source is an infrared light source, and the second light source is a visible light source; the first detector is an infrared light camera, and the second detector is a visible light camera.

10. The flip-chip offset measurement system of claim 2, wherein, The light source assembly further comprises a first modulation unit configured to modulate the first light beam and a second modulation unit configured to modulate the second light beam; and the imaging assembly further comprises a third modulation unit configured to modulate the first signal light and a fourth modulation unit configured to modulate the second signal light.

11. The flip-chip offset measurement system of claim 2, wherein, A long-wave band-pass filter is arranged in front of the first detector, and a short-wave band-pass filter is arranged in front of the second detector.

12. A method of measuring misregistration of flip chips, comprising: The flip chip is used to be attached to the substrate, and the first target and the second target are respectively arranged in the interior and on the surface of the flip chip, and the first target and the second target are located on the same side of the flip chip. The offset measurement method comprises: controlling the first light source to emit the first light beam to penetrate the flip chip and irradiate the first target in the deep layer, and acquiring a first image containing the first target from the first detector; controlling the second light source to emit the second light beam to irradiate the second target on the surface of the flip chip, and acquiring a second image containing the second target from the second detector; wherein the first light source is an infrared light source, and the second light source is a visible light source; acquiring a first offset of the flip chip relative to the substrate based on the first image, and acquiring a second offset of the flip chip relative to the substrate based on the second image; obtaining an attachment offset of the flip chip according to the first offset and the second offset.

13. The flip-chip offset measurement method of claim 12, wherein, The method for acquiring the first offset of the flip chip relative to the substrate based on the first image comprises: performing morphological denoising on the first image; determining a best matching position of the first image after noise reduction and the predefined template according to the predefined template, wherein the predefined template comprises at least one sub-image with the same shape or pattern as the first target; determining the first coordinate of the first target based on the best matching position; determining the first offset of the flip chip relative to the substrate according to the first coordinate.

14. The flip-chip offset measurement method of claim 13, wherein, The determining of the best matching position of the first image after noise reduction and the predefined template according to the predefined template comprises: sliding the predefined template and comparing with the first image after noise reduction pixel by pixel; calculating the similarity of the first image after noise reduction and the sub-image on the predefined template; taking the position with the highest similarity as the best matching position of the first image after noise reduction and the predefined template.

15. The flip-chip offset measurement method of claim 13, wherein, The obtaining of the second offset of the flip chip relative to the substrate based on the second image comprises: performing sub-pixel edge detection on the second image to obtain the pixel gray scale distribution of the second image; determining the second coordinate of the second target based on the pixel gray scale distribution of the second image; determining the second offset of the flip chip relative to the substrate according to the second coordinate.

16. The offset measurement method of the flip chip according to any one of claims 12-15, applied to the offset measurement system of the flip chip according to any one of claims 1-11.

Images