Interposer and preparation method thereof, and photoelectric co-packaging structure

Abstract

The invention provides an interposer and a preparation method thereof, and a photoelectric co-packaging structure, and the interposer comprises a substrate which comprises a glass substrate or a quartz substrate; the functional layer is arranged on the substrate, the refractive index of the functional layer is higher than that of the substrate, and the optical structure arranged on the functional layer at least comprises a micro-nano optical structure. The interposer realizes integration of an optical structure through the preset functional layer, and solves the problems of difficult micro-nano processing, difficult alignment, low integration level and the like of a glass material.

Description

Technical Field

[0001] The present application relates to the technical field of co-packaged optics, and particularly relates to an interposer, a preparation method thereof, and a co-packaged optical structure. Background Art

[0002] In the co-packaged optics (CPO) technology, the interposer, as a key carrier connecting the photonic chip, the control chip and the external high-speed channel, the material selection and integration process thereof determine the signal quality and transmission efficiency of the entire co-packaged optical system.

[0003] Currently, the mainstream interposers mostly adopt polymer and silicon-based materials, but these materials cannot solve the signal loss problem during high-frequency transmission. In contrast, glass materials have superior optical properties and low dielectric loss, and gradually become a powerful choice for co-packaged optics technology. In the existing co-packaged optical solutions based on glass interposers, it is generally dependent on the thermal ion exchange process to form a refractive index modulation region in the alkali-doped glass to construct an embedded optical waveguide structure.

[0004] However, such glass interposers highly depend on the chemical composition of the glass material and the heat treatment parameters, and it is difficult to be compatible with the integrated requirements of complex structures. Moreover, the alignment requirements between such glass waveguides and silicon photonic chips are extremely high, and it is difficult to ensure high-precision registration during the manufacturing process, resulting in low coupling efficiency. Summary of the Invention

[0005] The present application provides an interposer, a preparation method thereof, and a co-packaged optical structure. The interposer realizes the integration of the optical structure through a pre-set functional layer, and solves the problems of difficult micro-nano processing, difficult alignment, and low integration degree of glass materials.

[0006] The first aspect of the present application provides an interposer, including: a substrate, the substrate includes a glass substrate or a quartz substrate; a functional layer, the functional layer is disposed on the substrate, and the refractive index of the functional layer is higher than that of the substrate, and the optical structure disposed on the functional layer at least includes a micro-nano optical structure.

[0007] In a possible implementation manner, the optical structure disposed on the functional layer further includes an alignment structure.

[0008] In a possible implementation manner, the optical structure disposed on the functional layer further includes an optical waveguide structure.

[0009] In a possible implementation manner, the functional layer includes an inorganic material layer, and the material of the inorganic material layer includes at least one of silicon, polysilicon, amorphous silicon, tantalum oxide, silicon nitride, titanium dioxide, gallium nitride, and hafnium oxide.

[0010] In a possible implementation, the intermediate layer further includes: a distributed Bragg reflector structure, which is disposed between the substrate and the functional layer.

[0011] In a possible implementation, the intermediate layer further includes: an optical waveguide layer, which is disposed above the functional layer, and the optical waveguide layer includes a core waveguide structure.

[0012] In a possible implementation, a window is formed on the top surface of the intermediate layer, the window is located outside the core waveguide structure, and the window corresponds to the micro-nano optical structure and is connected to the surface of the micro-nano optical structure.

[0013] In a possible implementation, the optical waveguide layer further includes: a lower cladding layer, which is disposed between the functional layer and the core waveguide structure; and / or, an upper cladding layer, which covers the core waveguide structure.

[0014] In a possible implementation, the intermediate layer further includes: a bonding module, which is bonded above the functional layer, and at least one of the optical waveguide layer and the functional layer is disposed in the bonding module.

[0015] The second aspect of the present application provides a method for manufacturing an intermediate layer, including:

[0016] Providing a substrate and forming a functional layer on the substrate.

[0017] Using a photolithography process to etch and form an optical structure in the functional layer, and the optical structure at least includes a micro-nano optical structure.

[0018] The third aspect of the present application provides an optoelectronic co-packaging structure, including: the intermediate layer as described above; an optical chip and an electrical chip, both the optical chip and the electrical chip are electrically connected to the top surface of the intermediate layer; and an optical fiber, which is coupled to the intermediate layer.

[0019] For the intermediate layer, its manufacturing method, and the optoelectronic co-packaging structure provided by the present application, a functional layer is disposed above the substrate in the intermediate layer, and the functional layer is made of a high refractive index material, having a significant optical contrast compared to the substrate. Moreover, the functional layer is suitable for micro-nano processing, and the optical structure disposed in the functional layer at least includes a micro-nano optical structure. In this way, by pre-setting the functional layer in the intermediate layer made of glass or quartz, and integrating recognizable optical structures in the functional layer, in-situ manufacturing of micro-nano optical structures is realized. Also, the functional layer can also serve as the basis for forming the optical waveguide layer, enabling co-alignment of the optical waveguide layer and the optical structure without relying on the thermal ion exchange process, which is beneficial to achieving efficient coupling between the optical structure and the optical waveguide layer. Thus, the problems of difficult micro-nano processing, difficult alignment, and low device integration of glass materials are solved, which is beneficial to improving the density, coupling efficiency, and automated packaging ability of the optoelectronic co-packaging structure. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0021] Figure 1 Schematic diagram of the film stack of an interposer layer provided by an embodiment of the present application;

[0022] Figure 2 Schematic diagram of the structure of an optical and electrical co-packaging structure provided by an embodiment of the present application;

[0023] Figure 3 Schematic diagram of the structure of some micro-nano optical structures provided by an embodiment of the present application;

[0024] Figure 4 Schematic diagram of the structure of some alignment structures provided by an embodiment of the present application;

[0025] Figure 5 Schematic diagram of the structure of an interposer layer provided by an embodiment of the present application;

[0026] Figure 6 Schematic diagram of the structure of another interposer layer provided by an embodiment of the present application;

[0027] Figure 7 Schematic diagram of the structure of the third interposer layer provided by an embodiment of the present application;

[0028] Figure 8 Schematic diagram of the structure of the fourth interposer layer provided by an embodiment of the present application;

[0029] Figure 9 Flowchart of the steps of the preparation method of the interposer layer provided by an embodiment of the present application;

[0030] Figure 10 Flowchart of the manufacturing process of an optical and electrical co-packaging structure provided by an embodiment of the present application.

[0031] Explanation of the reference numerals:

[0032] 100 - Interposer layer;

[0033] 100a - Base module; 100b - Bonding module;

[0034] 110 - Substrate; 120 - Functional layer; 120a - Optical structure; 130 - Optical waveguide layer; 140 - DBR structure; 150 - Glass via hole; 160 - Redistribution layer;

[0035] 101 - Window; 121 - Micro - nano optical structure; 122 - Alignment structure; 123 - Optical waveguide structure; 131 - Core layer; 131a - Core waveguide structure; 132 - Lower cladding layer; 133 - Upper cladding layer;

[0036] 1211 - Microlens array; 1212 - Grating coupler;

[0037] 200 - Optical chip; 300 - Electrical chip; 400 - Optical fiber; 500 - Circuit board. Detailed implementation manners

[0038] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0039] With the booming development of artificial intelligence, high - performance computing and big data technologies, the global data traffic has increased sharply, posing higher requirements for data transmission rate and power consumption. The traditional inter - chip electrical interconnection technology is limited by problems such as radio frequency loss and crosstalk noise caused by metal transmission lines and packaging substrates, making it difficult to meet the current data traffic throughput requirements and becoming a key bottleneck restricting the further improvement of system performance.

[0040] As an emerging optoelectronic integration technology, the co - packaging technology of optics and electricity tightly integrates an optical engine and an Application - Specific Integrated Circuit (ASIC) chip in the same package, which can effectively shorten the transmission distance of optoelectrical signals, reduce transmission loss and delay, and has become the mainstream packaging solution to address the bandwidth bottleneck and power consumption problems of traditional electrical interconnections.

[0041] In the co - packaging architecture of optics and electricity, the interposer, as a key carrier connecting the photonic chip, driver chip, main control chip and external high - speed channels, the material selection and integration process thereof determine the signal quality and transmission efficiency of the entire co - packaging system. The current mainstream interposer technologies mostly use polymer and silicon - based materials, which cannot solve the signal loss problem during high - frequency transmission. In contrast, glass materials have excellent optical properties and low dielectric loss, making them a strong candidate in the co - packaging solution. In recent years, with the mature application of the through - Glass Via (TGV) technology and the Redistribution Layer (RDL) technology on glass substrates, the optoelectronic interconnection platform based on glass interposers is gradually moving towards the industrialization stage.

[0042] The existing optoelectronic co-packaging technology based on glass interposers has significant advantages in achieving high-speed and high-density optoelectronic interconnections. However, it still faces several key technical challenges, mainly including the following two points:

[0043] 1. Difficult to achieve efficient co-integration of micro-nano optical structures on a glass substrate: The current mainstream solutions mostly adopt the thermal ion exchange process to form buried refractive index modulation regions in alkali-doped glass to construct waveguide channels. Although this process is relatively mature, it has strict requirements for glass composition and thermal diffusion conditions, and the waveguide structure is deeply buried inside the glass. Since the thermal ion exchange process itself is difficult to be compatible with high-precision micro-nano processing technologies (such as etching, lithography, nanoimprinting, etc.), if subsequent micro-nano optical elements such as microlenses and gratings need to be constructed on the same glass substrate, great manufacturing challenges are often faced. This not only makes it difficult to co-optimize the design of micro-nano structures with waveguide structures, but also may rely on means such as laser direct writing or external device bonding, resulting in problems such as increased processing complexity and decreased coupling efficiency, seriously restricting the integration compactness and manufacturing flexibility of the overall packaging system.

[0044] 2. Difficult alignment recognition due to the transparent characteristics of glass, restricting the development of automated packaging processes: Since the glass substrate has high light transmittance in the visible and near-infrared bands, traditional vision-based automatic alignment systems are difficult to form clear and recognizable marker patterns on its surface, thus affecting the alignment accuracy and automated assembly efficiency. Especially in industrial packaging scenarios that require high-throughput and high-precision alignment, the lack of an effective alignment reference plane or recognition structure has become a technical bottleneck restricting the improvement of the automated manufacturing capabilities of glass-based platforms.

[0045] In view of this, the embodiments of the present application provide an interposer, a preparation method thereof, and an optoelectronic co-packaging structure. A functional layer is provided on a substrate in the interposer. The functional layer is made of a high refractive index material and has a significant optical contrast compared to the substrate. Moreover, the functional layer is suitable for micro-nano processing, and the optical structures provided in the functional layer at least include micro-nano optical structures. In this way, by pre-setting a functional layer in an interposer made of glass or quartz, the integration of recognizable optical structures is realized in the functional layer, achieving the in-situ manufacturing of micro-nano optical structures. And the functional layer can also serve as the basis for forming an optical waveguide layer, enabling the co-alignment of the optical waveguide layer and the optical structure without relying on the thermal ion exchange process, which is beneficial to achieving efficient coupling between the optical structure and the optical waveguide layer. Thus, the problems of difficult micro-nano processing, difficult alignment, and low device integration of glass materials are solved, which is beneficial to improving the density, coupling efficiency, and automated packaging ability of the optoelectronic co-packaging structure.

[0046] Figure 1 This is a schematic diagram of the film stack of an interposer provided by the embodiments of the present application. Refer to Figure 1As shown in the figure, the intermediate layer 100 provided by the embodiment of the present application includes a substrate 110 and a functional layer 120, and the functional layer 120 is disposed on the substrate 110.

[0047] The substrate 110 includes a glass substrate or a quartz substrate. For example, the substrate 110 is a fused quartz substrate. Glass and quartz have excellent optical properties and high-frequency characteristics, low dielectric loss, and can reduce signal loss during high-frequency transmission. At the same time, glass and quartz have a low coefficient of thermal expansion, which can well solve the problem of warping of the intermediate layer 100 caused by heat generation of chips (such as Figure 2 the optical chip 200 and the electrical chip 300 shown in the figure). Moreover, glass and quartz have a large Young's modulus, high hardness, and good surface flatness, and can achieve fine line pitch and smaller package size. Therefore, using glass and quartz as the substrate 110 can achieve lower electrical transmission loss, higher transmission rate, and higher integration.

[0048] A high refractive index material can be used to deposit and form the functional layer 120 on the substrate 110, and the functional layer 120 can be made of a material suitable for micro-nano processing. That is to say, the functional layer 120 has a high refractive index, significant optical contrast, and is suitable for micro-nano processing.

[0049] For example, the functional layer 120 may include an inorganic material layer. The inorganic materials that can be selected for the inorganic material layer include, but are not limited to, silicon, polysilicon, amorphous silicon, tantalum oxide, silicon nitride, titanium dioxide, gallium nitride, hafnium oxide. These inorganic materials are common dielectric materials in micro-nano optics. Using the inorganic material layer formed by these inorganic materials as the functional layer 120 enables the functional layer 120 to have good lithographic pattern processing function, facilitating the formation of an optical structure 120a in the functional layer 120 (such as Figure 2 and Figure 3 the micro-nano optical structure 121 shown in the figure). Moreover, compared with the substrate 110 of glass or quartz, the inorganic material layer made of these inorganic materials has a higher refractive index, forming an obvious refractive index difference between the functional layer 120 and the substrate 110, and the two have significant optical contrast, so that the functional layer 120 can be clearly recognized in the visible light or near-infrared band, and the functional layer 120 can be used for high-precision automatic alignment and pattern overlay.

[0050] In some examples, the functional layer 120 may further include a metal material layer, and the metal material layer may be disposed below the inorganic material layer. That is to say, the functional layer 120 may include a metal material layer and an inorganic material layer stacked in sequence. The metal material of the metal material layer is, for example, aluminum, titanium, chromium, etc. The metal material has high reflectivity and high recognition, can enhance the image recognition effect of the functional layer 120 in the automated system, and further improve the accuracy of automatic alignment and pattern overlay.

[0051] Thus, by disposing the functional layer 120 on the substrate 110, the optical structure 120a can be processed and formed using the good micro-nano processing performance of the functional layer 120, so as to integrate the optical structure 120a into the interposer 100. The problem of difficult micro-nano processing of the substrate 110 made of glass and quartz materials is solved, the difficulty of fabricating the optical structure 120a in the interposer 100 is reduced, which is beneficial to improving the coupling efficiency of the optical structure 120a in the interposer 100, and enhancing the overall integration, compactness and flexibility of the optoelectronic co-packaging structure.

[0052] Meanwhile, the functional layer 120 with a high refractive index has a significant optical contrast and is easy to be recognized by an automated system for image recognition, which can improve the accuracy of automatic alignment and pattern overlay. Furthermore, the automated assembly efficiency of the optoelectronic co-packaging structure is improved, and the automatic alignment accuracy of the optoelectronic co-packaging structure is enhanced. The automated manufacturing capacity of the glass-based optoelectronic co-packaging structure is improved, and the performance of the glass-based optoelectronic co-packaging structure is enhanced.

[0053] Continue to refer to Figure 1 , the interposer 100 may further include an optical waveguide layer 130, and the optical waveguide layer 130 is disposed on the functional layer 120. The optical waveguide layer 130 includes a core layer 131, and the core layer 131 is configured to include at least one core waveguide structure 131a (see Figure 2 shown). When there are multiple core waveguide structures 131a, the multiple core waveguide structures 131a may be distributed in different regions of the core layer 131. The core waveguide structure 131a forms an optical path channel for realizing the transmission of optical signals between the interposer 100 and an external medium (such as an optical fiber 400).

[0054] The core layer 131 can be made of a material with a relatively low refractive index. For example, the material for fabricating the core layer 131 is germanium-doped silica (Ge:SiO2) or silicon oxynitride (SiON). In this way, the core waveguide structure 131a formed by the core layer 131 has a relatively low refractive index, and low-loss transmission of optical signals can be achieved.

[0055] On this basis, the optical waveguide layer 130 may further include a lower cladding layer 132, and the lower cladding layer 132 is disposed between the functional layer 120 and the core layer 131. The lower cladding layer 132 can be made of a material with a refractive index lower than that of the core layer 131, and the material of the lower cladding layer 132 is, for example, silica. The lower cladding layer 132 can prevent the leakage of the optical field from the substrate 110, and its thickness is usually designed to be large enough to ensure that the light can be effectively confined in the core waveguide structure 131a.

[0056] The optical waveguide layer 130 may further include an upper cladding layer 133. The upper cladding layer 133 is disposed on the core layer 131 and covers the core waveguide structure 131a. The upper cladding layer 133 serves as a protective layer to protect the core waveguide structure 131a and improve the reliability of the core waveguide structure 131a. At the same time, the upper cladding layer 133 may also serve as an encapsulation structure for the interposer 100. The upper cladding layer 133 may be located on the top surface of the interposer 100, and the upper cladding layer 133 plays a role in protecting the entire interposer 100. The upper cladding layer 133 may also select a material with a refractive index lower than that of the core layer 131. For example, the material of the upper cladding layer 133 may be silicon dioxide.

[0057] Figure 2 FIG. [ID] is a schematic structural diagram of an optical and electrical co-packaging structure provided by an embodiment of the present application. Refer to Figure 2 As shown, an embodiment of the present application further provides an optical and electrical co-packaging structure. The optical and electrical co-packaging structure includes an interposer 100, and the structure of the interposer 100 may adopt the Figure 1 film stack structure shown in the figure.

[0058] On this basis, the optical and electrical co-packaging structure may further include an optical chip 200 and an electrical chip 300. The optical chip 200 and the electrical chip 300 may be packaged on the top surface of the interposer 100, and the optical chip 200 and the electrical chip 300 may be packaged on a circuit board (not shown in the figure) through the interposer 100. A redistribution layer 160 may be disposed on the top surface of the interposer 100, and glass vias 150 may be provided in the middle layer. The glass vias 150 penetrate both side surfaces of the middle layer. The optical chip 200 and the electrical chip 300 are electrically connected to the circuit board through the redistribution layer 160 and the glass vias 150, and the redistribution layer 160 may also implement the interconnection between the optical chip 200 and the electrical chip 300.

[0059] Among them, the optical chip 200 is, for example, a Photonic Integrated Circuit (PIC for short). The optical chip 200 uses light waves as a carrier to complete information transmission and data operation. The electrical chip 300 is, for example, an Application Specific Integrated Circuit (ASIC for short). The electrical chip 300 includes control and operation functions, and can modulate and demodulate optical signals to realize the analysis, processing, and transmission of optical signals.

[0060] The optical and electrical co-packaging structure realizes the integration of the optical chip 200 and the electrical chip 300 through the interposer 100 to achieve high-speed data transmission and processing. This integration method shortens the electrical interconnection length between the optical signal input and the operation unit, reduces the size, improves the efficiency, and reduces the power consumption.

[0061] Continue to refer toFigure 2 The optical-electronic co-packaging structure further includes an optical fiber 400 for transmitting optical signals. As shown in the figure, optical fibers 400 are disposed on both opposite sides of the interposer 100. One of the two optical fibers 400 serves as the optical fiber 400 for introducing optical signals into the interposer 100, and the other optical fiber 400 serves as the optical fiber 400 for receiving the optical signals output from the interposer 100. At this time, the optical fiber 400 through which the optical signals enter the interposer 100 can also be coupled to an external light source. The optical signals are generated by the external light source, transmitted through the optical fiber 400 to the optical devices (including the optical devices in the optical waveguide layer 130 and the functional layer 120) in the interposer 100, transmitted to the optical chip 200 through the optical devices, and after the optical signals are processed by the optical chip 200, the processed optical signals are transmitted to the optical fiber 400 on the output side.

[0062] Of course, the optical fiber 400 can also be disposed only on one side of the interposer 100. For example, an external light source can be directly disposed on the side where the optical signals enter the interposer 100, and the external light source generates optical signals and directly transmits the optical signals into the interposer 100.

[0063] Among them, the optical fiber 400 (or the external light source) can be disposed corresponding to the position of the core waveguide structure 131a. In this way, the coupling distance between the optical fiber 400 (or the external light source) and the core waveguide structure 131a is smaller, the transmission efficiency of the optical signals between the two is higher, and the transmission loss is smaller.

[0064] As Figure 2 shown in the figure, the optical structures 120a processed in the functional layer 120 are schematically shown, and these optical structures 120a include micro-nano optical structures 121. The micro-nano optical structure 121 is an optical element with a size below 100 nanometers. The micro-nano optical structure 121 can control the diffraction and propagation of light to achieve new optical properties.

[0065] Figure 3 are schematic structural diagrams of some micro-nano optical structures provided by the embodiments of the present application. Combining Figure 2 and Figure 3 shown, the micro-nano optical structures 121 formed in the functional layer 120 include, but are not limited to, microlens arrays, grating couplers, collimators, mirrors, etc. The micro-nano optical structure 121 can adjust optical signals, control characteristics such as the propagation direction, intensity, and polarization of light, and realize functions such as high-efficiency beam shaping, polarization control, and optical antireflection. Thus, the integration and working efficiency of the optical-electronic co-packaging structure are improved, precise control of optical signals is achieved, and the stability and reliability of the optical-electronic co-packaging structure are enhanced.

[0066] Figure 4 are schematic structural diagrams of some alignment structures provided by the embodiments of the present application. Referring to Figure 4As shown, based on the micro-nano optical structure 121, the optical structure 120a formed in the functional layer 120 may further include an alignment structure 122. The alignment structure 122 is a visible pattern used to determine the position and orientation of the subsequently formed pattern structure. The alignment structure 122 may have different shapes and sizes, and a suitable alignment structure 122 can be selected according to the pattern structure to be aligned.

[0067] As Figure 4 shown in [reference], the alignment structure 122 may include a frame structure, a cross structure, an annular structure, and a circular structure. In addition, the alignment structure 122 may further include a linear structure, a triangular structure, etc. The linear alignment structure 122 may include multiple spaced-apart lines, and the thickness and spacing of the lines in different alignment structures may be different.

[0068] The alignment structure 122 in the functional layer 120 can be used as a reference for the pattern structure (such as the core waveguide structure 131a) formed after the functional layer 120 to achieve automatic alignment of the subsequent pattern structure. The high refractive index of the functional layer 120 enables it to be clearly identified in the visible or near-infrared band. The alignment structure 122 in the functional layer 120 can be used for high-precision automatic alignment and pattern overlay. Thus, the manufacturing efficiency and processing accuracy of the optoelectronic co-packaging structure can be improved, and the performance of the optoelectronic co-packaging structure can be enhanced.

[0069] Figure 5 This is a schematic structural diagram of an interposer provided by an embodiment of the present application. The optical structure 120a formed in the functional layer 120 may further include an optical waveguide structure 123. The optical waveguide structure 123 is a guiding structure that guides light waves to propagate therein. The optical waveguide structure 123 formed in the functional layer 120 may be a planar dielectric optical waveguide, and the planar dielectric optical waveguide confines the light waves to propagate within the dielectric film. When the thickness of the functional layer 120 is relatively large, a strip-shaped dielectric optical waveguide may also be formed in the functional layer 120 in a patterned manner, and the strip-shaped dielectric optical waveguide confines the light waves to propagate within the strip.

[0070] For some functional materials with good optical waveguide properties, such as high-refractive-index materials like single-crystalline silicon, tantalum oxide, and silicon nitride. After depositing these materials to form the functional layer 120, while processing the micro-nano optical structure 121 and the alignment structure 122 in the functional layer 120, the optical waveguide structure 123 can be etched synchronously or subsequently.

[0071] Since the functional layer 120 is made of a high-refractive-index material, the optical waveguide structure 123 formed in the functional layer 120 has a high refractive index. Compared with the core waveguide structure 131a with a lower refractive index, the high-refractive-index optical waveguide structure 123 has a higher ability to confine the light field, and the high-refractive-index optical waveguide structure 123 has a smaller mode field difference from the optical chip 200.

[0072] Thus, by forming a high-refractive-index optical waveguide structure 123 in the functional layer 120, the confinement ability of the optical field is enhanced, and the bending radius of the optical waveguide structure 123 can be reduced. In this way, the size of the optical waveguide structure 123 can be smaller and the integration degree can be higher. Moreover, the problems of long coupling length and large coupling loss caused by the mode field difference between the optical waveguides in the intermediate layer 100 and the optical waveguides in the optical chip 200 can also be solved. Higher-density integration and efficient optical signal transmission and modulation of the optoelectronic co-packaging structure are realized.

[0073] The core waveguide structure 131a in the optical waveguide layer 130 and the optical waveguide structure 123 in the functional layer 120 act synergistically. The coupling connection between the core waveguide structure 131a and the external optical fiber 400 is more reliable and has less loss. The optical waveguide structure 123 can optimize the transmission path of the optical signal between the intermediate layer 100 and the optical chip 200. Among them, a coupling structure can be formed by coupling between the core waveguide structure 131a and the optical waveguide structure 123, which can efficiently transmit the optical signal from the core waveguide structure 131a to the optical waveguide structure 123, and can also efficiently transmit the optical signal from the optical waveguide structure 123 to the core waveguide structure 131a. This coupling structure utilizes the evanescent wave coupling of the optical field between different waveguides to ensure that the optical signal can be coupled in a low-loss manner.

[0074] With such a setting, in this embodiment, a functional material with high refractive index, easy for micro-nano processing and good optical recognition performance can be pre-deposited on the substrate 110 of glass or quartz as the functional layer 120, and then the optical structure 120a can be directly constructed in the functional layer 120, referring to the previous path of laser processing or bonding additional optical elements at the re-packaging end, realizing the high-precision in-situ manufacturing of the micro-nano optical structure 121. It not only avoids the problem of insufficient micro-nano processing ability of glass or quartz, but also eliminates the integration complexity and packaging instability caused by the subsequent bonding of micro-structures, improving the optical coupling efficiency and structural reliability of the system.

[0075] Moreover, the present application adopts a process route of "optical first and waveguide later". First, the optical structure 120a is constructed in the functional layer 120, then the lower cladding layer 132 and the core layer 131 are deposited, and the core layer 131 is accurately etched in alignment with the alignment structure 122 to form the core waveguide structure 131a buried in the intermediate layer 100. This inverted structure design not only realizes the cooperative alignment of the core waveguide structure 131a and the optical structure 120a, but also greatly improves the positioning accuracy in the automated overlay etching and assembly process by introducing the optically recognizable alignment structure 122, overcoming the problems such as difficult recognition of alignment features and difficult execution of automated processes due to the transparency of glass or quartz in the traditional process.

[0076] In addition, compared with the traditional ion-exchange waveguide solution, there are problems of low coupling efficiency and complex packaging caused by the need for a long-distance gradual change region to achieve mode matching. In this embodiment, by reasonably designing the thickness of the functional layer 120 and the parameters of the core waveguide structure 131a, the vertical or oblique coupling between the optical structure 120a and the core waveguide structure 131a can be efficiently achieved, significantly compressing the device pitch, improving the packaging integration density, reducing the optical loss, and enhancing the bandwidth and transmission efficiency of the optoelectronic co-packaging structure.

[0077] Figure 6 FIG. is a schematic structural diagram of another intermediate layer provided by an embodiment of the present application. Refer to Figure 6 As shown, in some embodiments, the intermediate layer 100 may further include a Distributed Bragg Reflector (DBR) structure. The DBR structure 140 may be disposed between the substrate 110 and the functional layer 120. A plurality of alternately deposited low-refractive-index and high-refractive-index film layers may be deposited on the substrate 110 and under the functional layer 120 to form the DBR structure 140.

[0078] When light passes through different media, reflection occurs at the interface, and the magnitude of the reflectivity is related to the refractive index between the media. The DBR structure 140 is formed by alternately stacking thin films of different refractive indices in a periodic manner. When light passes through these thin films of different refractive indices, the light reflected from each layer undergoes constructive interference due to the change in the phase angle and then combines with each other to obtain strongly reflected light. Thus, the DBR structure 140 can reflect the light leaking to the substrate 110 back to the optical structure 120a, improve the reflection efficiency of the vertically incident light, enhance the reflection efficiency of the micro-nano optical structure 121 or regulate its working bandwidth, and achieve better coupling control between the micro-nano optical structure 121 and the core waveguide structure 131a.

[0079] For example, before forming the functional layer 120, materials such as silicon dioxide and tantalum oxide, titanium dioxide, etc. are alternately deposited on the substrate 110 to form 4 to 6 pairs of λ / 4n structures. As a specific example, silicon nitride (n≈2.0) and silicon dioxide (n≈1.45) materials are used, with layer thicknesses of 120 nm and 160 nm respectively, and the cycle is repeated 5 times to form the DBR structure 140.

[0080] Figure 7 FIG. is a schematic structural diagram of a third intermediate layer provided by an embodiment of the present application. Refer to Figure 7As shown, in some embodiments, a window 101 may also be formed on the top surface of the intermediate layer 100. The window 101 is located in a region outside the core waveguide structure 131a in the optical waveguide layer 130 to avoid affecting the core waveguide structure 131a. Moreover, the window 101 corresponds to the micro-nano optical structure 121 and is connected to the surface of the micro-nano optical structure 121.

[0081] With such an arrangement, on the basis of maintaining the integrity of the micro-nano optical structure 121, the dielectric material above the micro-nano optical structure 121 is removed, so that the micro-nano optical structure 121 is directly exposed to air or the subsequent encapsulation medium. Thus, a clean interface where the micro-nano optical structure 121 is exposed is obtained, and the optical signal can be directly transmitted by the micro-nano optical structure 121 through the air medium, which is beneficial to subsequent optical coupling or encapsulation operations.

[0082] For example, after the functional layer 120 and the optical waveguide layer 130 are both fabricated, the material covering the micro-nano optical structure 121 can be partially or completely removed by means such as dry etching (such as reactive ion etching, plasma etching) or wet etching (such as selective chemical etching). Based on the etching selectivity between different materials, the dielectric material can be removed while maintaining the complete morphology of the micro-nano optical structure 121.

[0083] Figure 8 This is a schematic structural diagram of the fourth intermediate layer provided by the embodiments of the present application. Referring to Figure 8 As shown, in some embodiments, the intermediate layer 100 can also be modularly designed. The module on the substrate 110 on which the functional layer 120 (or also including the optical waveguide layer 130) is formed is used as the basic module 100a, and a bonding module 100b is added on the basis of the basic module 100a. At least one of the optical waveguide layer 130 and the functional layer 120 is provided in the bonding module 100b. The bonding module 100b is bonded to the basic module 100a to jointly form the intermediate layer 100.

[0084] After the optical structure 120a in the functional layer 120 or the core waveguide structure 131a in the optical waveguide layer 130 is fabricated on the substrate 110, a material with good leveling performance (such as silicon dioxide) is deposited on its surface, and the surface is polished to the required thickness and optical flatness through a Chemical Mechanical Polishing (CMP) process to form the basic module 100a. Then, the basic module 100a is bonded to the bonding module 100b through this surface to form the intermediate layer 100.

[0085] The intermediate layer 100 is formed by bonding the basic module 100a and the bonding module 100b, and the original intermediate layer 100 can be disassembled into multiple modules. As Figure 8As shown in (a) thereof, the functional layer 120 can be provided only in the base module 100a to form the optical structure 120a, while the optical waveguide layer 130 is formed in the bonding module 100b. The bonding module 100b is bonded to the base module 100a to form the complete interposer 100. In this way, by modularizing the design of the interposer 100, quality control can be carried out on each module during the manufacturing process, reducing the risk of defects, improving the reliability of the interposer 100, and being beneficial to saving the manufacturing cost of the interposer 100.

[0086] The interposer 100 is formed by bonding the base module 100a and the bonding module 100b, and the stacking of optical devices can also be realized. As Figure 8 shown in (b) thereof, the base module 100a has a plurality of optical structures 120a formed in the functional layer 120, and the bonding module 100b bonded on the base module 100a also has a plurality of optical structures 120a formed in the functional layer 120. In this way, optical devices such as the optical waveguide structure 123 and the micro-nano optical structure 121 (such as a microlens array, a grating coupler, a mirror, etc.) can be further stacked, which is also beneficial to forming a complex optical path design and a vertical integration structure in the interposer 100.

[0087] Figure 9 It is a flowchart of the steps of the method for preparing the interposer provided by the embodiment of the present application. Figure 10 It is a flowchart of the manufacturing process of an optoelectronic co-packaging structure provided by the embodiment of the present application. Among them, Figure 10 Taking Figure 1 the film stack structure of the interposer 100 shown as an example, the manufacturing process flow of the optoelectronic co-packaging structure is schematically shown. The following will combine Figure 9 and Figure 10 shown to describe in detail the manufacturing process of the interposer 100 and the subsequent manufacturing process of forming the optoelectronic co-packaging structure.

[0088] Referring to Figure 9 shown, the embodiment of the present application also provides a method for preparing an interposer 100. This preparation method is used to prepare the aforementioned interposer 100. This preparation method includes the following steps:

[0089] S100. Provide a substrate and form a functional layer on the substrate.

[0090] Referring to Figure 10 shown in (a) thereof, first provide a substrate 110 made of glass or quartz. For example, provide a fused silica glass with a thickness of 1 mm as the substrate 110. Referring to Figure 10As shown in (b) thereof, a functional layer 120 is then deposited on the substrate 110 using a high refractive index material. For example, a plasma enhanced chemical vapor deposition (PECVD) process is used to deposit an amorphous silicon (α-Si) thin film with a thickness of 600 nm on the surface of the substrate 110 as the functional layer 120. Amorphous silicon has a high refractive index, good etching properties and structural stability, and can be used for subsequent processing of the optical structure 120a.

[0091] S200. A photolithography process is used to etch and form an optical structure in the functional layer, and the optical structure at least includes a micro-nano optical structure.

[0092] Refer to Figure 10 As shown in (c) thereof, a photolithography process is then used to etch and form an optical structure 120a in the functional layer 120 (only the micro-nano optical structure 121 is shown in the figure, and actually also includes an alignment structure 122, and may also include the aforementioned optical waveguide structure 123). For example, using a stepper photolithography exposure and reactive ion etching technology, a microlens array 1211 and a grating coupler 1212 are constructed on the functional layer 120 formed by amorphous silicon, and an alignment structure 122 (such as a cross, etc.) is made at a specific position as an auxiliary structure for subsequent alignment and assembly.

[0093] When the intermediate layer 100 further includes an optical waveguide layer 130 directly formed on the functional layer 120, refer to Figure 10 As shown in (d) thereof, then, a lower cladding layer 132 of the optical waveguide layer 130 is deposited on the optical structure 120a constructed on the functional layer 120. For example, through a plasma enhanced chemical vapor deposition process, a layer of silicon dioxide with a thickness of 15 μm is deposited on the optical structure 120a as the lower cladding layer 132. Refer to Figure 10 As shown in (e) thereof, the deposited lower cladding layer 132 can be polished flat by a chemical mechanical polishing process to facilitate subsequent construction of the core waveguide structure 131a.

[0094] Refer to Figure 10 As shown in (f) thereof, a core layer 131 is continuously deposited on the lower cladding layer 132. For example, a layer of silicon oxynitride with a thickness of 6.5 μm is deposited on the lower cladding layer 132 as the core layer 131, and the refractive index difference between the core layer 131 formed by silicon oxynitride and the lower cladding layer 132 formed by silicon dioxide below is 0.45%. Refer to Figure 10As shown in (g) therein, after defining the pattern of the core waveguide structure 131a by means of an exposure and development process, an etching process is used to construct the core waveguide structure 131a in the core layer 131. For example, an Inductively Couple Plasma (ICP) etching process is used to etch out the core waveguide structure 131a, and the coupling loss between the core waveguide structure 131a and the external optical fiber 400 is extremely low.

[0095] Referring to Figure 10 As shown in (h) therein, finally, a top cladding 133 is deposited on the core waveguide structure 131a to fabricate and form the interposer 100. For example, a layer of silicon dioxide with a thickness of 15 μm is deposited as the top cladding 133. Referring to Figure 10 As shown in (i) therein, through a chemical mechanical polishing process exposure, the top of the interposer 100 is made flat, and the co-construction of the optical waveguide layer 130 and the optical structure 120a (such as the micro-nano optical structure 121) in the glass or quartz-based interposer 100 is completed.

[0096] After the interposer 100 is fabricated, referring to Figure 10 As shown in (j) therein, a Laser-Induced Deep Etching (LIDE) technology is used to process high aspect ratio glass vias 150 (TGV) in the vertical direction in the glass or quartz-based interposer 100. For example, the aspect ratio of the glass via 150 is 20:1, the aperture of the glass via 150 is about 10 μm, the depth is 200 μm, and the profile uniformity is excellent. To further optimize the structure thickness, reduce the packaging stack height, and improve the focusing stability of the subsequent redistribution layer 160 (RDL) pattern definition, a thinning process is performed on the back surface of the entire substrate 110.

[0097] Referring to Figure 10 As shown in (k) therein, then, an electroplating process is used to complete the metal filling of the glass via 150, and a redistribution layer 160 is constructed on the surface of the interposer 100. Among them, constructing the redistribution layer 160 includes seed layer deposition, pattern electroplating, and resist stripping and etching processes to complete the metal interconnection pattern layout required for chip pin welding. Referring to Figure 10 As shown in (l) therein, finally, functional chips such as the optical chip 200 and the electrical chip 300 are precisely assembled with the interposer 100 through wire bonding or micro-bump welding technology, and the back surface of the interposer 100 is encapsulated on the circuit board 500 by using the glass via 150 to complete the construction of a high-density optoelectronic co-packaging structure.

[0098] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An intermediate layer, characterized in that, Comprising: a substrate, the substrate comprising a glass substrate or a quartz substrate; a functional layer, the functional layer being disposed on the substrate and having a refractive index higher than that of the substrate, and the optical structure provided by the functional layer at least comprising a micro-nano optical structure.

2. The interposer according to claim 1, wherein The optical structure provided by the functional layer further comprises an alignment structure.

3. The interposer according to claim 1, wherein The optical structure provided by the functional layer further comprises an optical waveguide structure.

4. The interposer according to any one of claims 1 to 3, characterized in that The functional layer comprises an inorganic material layer, and the material of the inorganic material layer comprises at least one of silicon, polysilicon, amorphous silicon, tantalum oxide, silicon nitride, titanium dioxide, gallium nitride, and hafnium oxide.

5. The interposer according to any one of claims 1 to 3, characterized in that Further comprising: a distributed Bragg reflector structure, the distributed Bragg reflector structure being disposed between the substrate and the functional layer.

6. The interposer according to any one of claims 1-3, characterized in that Further comprising: an optical waveguide layer, the optical waveguide layer being disposed on the functional layer, and the optical waveguide layer comprising a core waveguide structure.

7. The interposer according to claim 6, wherein A window is formed on the top surface of the intermediate layer, the window is located outside the core waveguide structure, and the window corresponds to the micro-nano optical structure and communicates with the surface of the micro-nano optical structure.

8. The interposer according to claim 6, wherein The optical waveguide layer further comprises: a lower cladding layer disposed between the functional layer and the core waveguide structure; and / or, an upper cladding layer covering the core waveguide structure.

9. The interposer according to any one of claims 1-3, characterized in that Further comprising: a bonding module, the bonding module being bonded on the functional layer, and at least one of an optical waveguide layer and a functional layer being provided in the bonding module.

10. A method for preparing an intermediate layer, characterized in that, Comprising: providing a substrate and forming a functional layer on the substrate; adopting a photolithography process to etch and form an optical structure in the functional layer, the optical structure at least comprising a micro-nano optical structure.

11. An optical and electrical co-packaging structure, characterized in that, Comprising: the intermediate layer according to any one of claims 1-9; an optical chip and an electrical chip, both the optical chip and the electrical chip being electrically connected to the top surface of the intermediate layer; an optical fiber, the optical fiber being coupled to the intermediate layer.

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