Three-dimensional package light engine based on glass substrate

Abstract

The application provides a glass substrate-based three-dimensional packaging light engine, comprising: a glass substrate, comprising opposite first and second surfaces, a cavity penetrating through the glass substrate being formed between the first and second surfaces, and a glass optical waveguide located inside the glass substrate, a first end of the glass optical waveguide extending to the cavity, and a second end of the glass optical waveguide being used for coupling connection with an external optical fiber; an optical functional chip, embedded and fixed in the cavity, and optically coupled with the first end of the glass optical waveguide; an electric functional chip, arranged on the first surface and electrically connected with the optical functional chip; and the second surface of the glass substrate is used for electrically connecting with a printed circuit board, so that the optical functional chip and the electric functional chip are electrically connected with the printed circuit board through the glass substrate.

Description

Technical Field

[0001] This invention relates to the field of integrated optoelectronic technology, and more specifically to a three-dimensional encapsulated optical engine based on a glass substrate. Background Technology

[0002] With the rapid development of artificial intelligence, high-performance computing, and data center scale, the data exchange rate and bandwidth density between chips are continuously increasing. Traditional packaging and system architectures based on electrical interconnects are gradually facing bottlenecks in terms of power consumption, bandwidth, and signal integrity. Optical interconnects, due to their advantages such as high bandwidth, low loss, and immunity to electromagnetic interference, are considered an effective way to solve the interconnection problems of high-performance computing systems and ultra-large-scale integrated systems. To meet the demands for higher integration and higher bandwidth density, optoelectronic co-packaging and 3D integrated packaging technologies are gradually becoming key areas of research and industrial focus.

[0003] Existing optoelectronic co-packaging and 3D packaging solutions mostly use organic substrates or silicon interposers to integrate optoelectronic devices with electrical functional chips. However, they still have certain limitations in high-frequency signal transmission, interconnect density, and optical coupling methods. On the one hand, the dielectric loss and thermal stability of traditional substrate materials under high-frequency conditions limit the overall performance of the system. On the other hand, the optical functional chips and external optical fibers usually rely on vertical grating coupling or complex optical alignment structures, which increases the difficulty of optical coupling and packaging complexity, hindering large-scale multi-core integration and high-reliability applications. Therefore, there is an urgent need for a 3D advanced packaging optical engine structure that can balance high-frequency electrical interconnect performance with flexible optical coupling methods to meet the development needs of future ultra-large-scale integrated communication interconnects. Summary of the Invention

[0004] In view of this, the present invention proposes a three-dimensional packaged optical engine based on a glass substrate to achieve optical interconnects with higher integration and higher bandwidth density, and solves the problems of limited high-frequency electrical interconnect performance and insufficient flexibility of optical coupling methods in existing optoelectronic co-packaging structures.

[0005] To achieve the above objectives, embodiments of the present invention provide a three-dimensional encapsulated optical engine based on a glass substrate, comprising: a glass substrate including opposing first and second surfaces, a cavity penetrating the glass substrate formed between the first and second surfaces, and a glass waveguide located inside the glass substrate, a first end of the glass waveguide extending into the cavity, and a second end of the glass waveguide for coupling connection with an external optical fiber; an optical functional chip embedded and fixed within the cavity, the optical functional chip being optically coupled to the first end of the glass waveguide; and an electrical functional chip disposed on the first surface and electrically connected to the optical functional chip; wherein, the second surface of the glass substrate is used for electrical connection with a printed circuit board, so that the optical functional chip and the electrical functional chip are electrically connected to the printed circuit board through the glass substrate.

[0006] According to an embodiment of the present invention, a first super-wiring layer is provided on the first surface, and the electrical functional chip is electrically connected to the optical functional chip through the first super-wiring layer; a second super-wiring layer is provided on the second surface, and a plurality of parallel glass vias are formed between the first surface and the second surface, the glass vias are filled with conductive material, and the first super-wiring layer and the second super-wiring layer are electrically connected through the conductive material; the second super-wiring layer, the conductive material and the first super-wiring layer form an electrical path for connecting the printed circuit board.

[0007] According to an embodiment of the present invention, a plurality of microbumps are also formed on the first surface, and the electrical functional chip is flip-chip bonded to the glass substrate through the plurality of microbumps and electrically connected to the first redistribution layer.

[0008] According to an embodiment of the present invention, a ball grid array is also formed on the second surface, and the printed circuit board is soldered to the three-dimensional packaged optical engine through the ball grid array and electrically connected to the second redistribution layer.

[0009] According to an embodiment of the present invention, the thickness of the glass substrate is greater than or equal to the thickness of the optical functional chip, and the upper surface of the optical functional chip is flush with the first surface.

[0010] According to an embodiment of the present invention, at least a portion of the side and bottom surfaces of the optical functional chip are filled and bonded to the glass substrate using UV-curable optical adhesive.

[0011] According to an embodiment of the present invention, the optical functional chip includes a waveguide structure coupled to a glass optical waveguide, and the waveguide structure and the glass optical waveguide are located at the same height.

[0012] According to an embodiment of the present invention, the roughness of the sidewall region of the cavity located between the optical functional chip and the glass waveguide is lower than a preset threshold.

[0013] According to an embodiment of the present invention, the electrical functional chip and the optical functional chip are stacked together.

[0014] According to an embodiment of the present invention, it further includes: an optical fiber connector for connecting the glass optical waveguide and the external optical fiber, for inputting laser light from the external optical fiber into the three-dimensional encapsulated optical engine, or for outputting laser light from the three-dimensional encapsulated optical engine to the external optical fiber.

[0015] Compared to existing technologies, this invention constructs a three-dimensional packaged optical engine structure based on a glass substrate. By integrating optical functional chips and glass waveguides within the glass substrate, it achieves efficient collaborative interconnection between optical functional units, electrical functional units, and external systems. The low dielectric loss of the glass substrate reduces attenuation during high-frequency signal transmission, improving the high-frequency performance of the package. The high flatness and mechanical stability of the glass surface minimize warping during larger-size packaging. The light-transmitting glass material supports light propagation within the substrate, greatly simplifying optical coupling. This invention improves high-frequency signal transmission performance while significantly enhancing the flexibility of optical coupling methods, making it suitable for future large-scale multi-chip integration and ultra-large-scale integrated communication interconnection applications. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 The diagram illustrates a three-dimensional encapsulated optical engine structure based on a glass substrate according to an embodiment of the present invention.

[0018] Reference numerals: 100-3D packaged optical engine; 10-glass substrate; 11-glass waveguide; 12-cavity; 13-glass via; 20-optical functional chip; 21-waveguide structure; 30-electrical functional chip; 40-printed circuit board; 50-fiber optic connector; 51-fiber optic cable; 61-first redistribution layer; 62-second redistribution layer; 71-microbump; 72-ball grid array; 80-UV-curable optical adhesive; 91-first dielectric layer; 92-second dielectric layer. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] Please see Figure 1 This embodiment provides a three-dimensional packaged optical engine 100 based on a glass substrate, which mainly includes a glass substrate 10, an optical functional chip 20, an electrical functional chip 30, multilayer redistribution layers 61 and 62 disposed at the upper and lower ends of the glass substrate 10, microbumps 71 disposed at the upper end of the glass substrate 10 and a ball grid array 72 formed by solder ball bumps disposed at the lower end of the glass substrate 10, and a multi-channel fiber optic connector 50 for optical signal introduction and extraction.

[0022] The glass substrate 10 includes a first surface (upper surface in this embodiment) and a second surface (lower surface in this embodiment) opposite each other. The glass substrate 10 can be made of a glass material with high flatness, low radio frequency loss, and high mechanical strength, such as borosilicate glass, quartz glass, or photosensitive glass. The thickness of the glass substrate 10 is preferably selected to ensure sufficient mechanical strength while taking into account the feasibility of through-hole processing; this invention does not impose a specific limitation.

[0023] In this embodiment, the glass substrate 10 contains a glass waveguide 11, a cavity 12 penetrating the glass substrate 10, and multiple glass vias 13. The glass waveguide 11 is disposed inside the glass substrate 10 and can be formed, for example, using femtosecond laser direct writing technology combined with thermal annealing, allowing its transmission loss to be controlled at a low level. The cavity 12 penetrating the glass substrate 10 is used to embed an optical functional chip 20, and the size of the cavity 12 matches the external dimensions of the optical functional chip 20. The glass vias 13 penetrate the upper and lower surfaces of the glass substrate 10 and are filled with a highly conductive material, such as copper, tungsten, or silver paste, to achieve vertical electrical interconnection between the upper and lower ends of the glass substrate 10. The arrangement density of the glass vias 13 can be designed according to interconnection requirements, providing a physical basis for high-density interconnection.

[0024] In this embodiment, the first end of the glass waveguide 11 extends toward the cavity 12 and terminates at the sidewall of the cavity 12. The second end of the glass waveguide 11 extends to the edge of the glass substrate 10 for coupling connection with the external optical fiber 51.

[0025] Please continue reading. Figure 1 In this embodiment, the optical functional chip 20 is embedded in the cavity 12 inside the glass substrate 10. The thickness of the glass substrate 10 is greater than or equal to the thickness of the optical functional chip 20. Preferably, the thickness of the optical functional chip 20 is substantially the same as the thickness of the glass substrate 10, and the upper surface of the optical functional chip 20 is substantially flush with the upper surface of the glass substrate 10 after embedding. Compared with conventional solutions that require significant thinning of the optical chip, the optical functional chip 20 of the present invention does not need to be excessively thinned, thereby effectively reducing the risk of warping and cracking during chip thinning, and improving yield and reliability. In addition, through this structural design, the continuity of the multiple redistribution layers on the upper end of the glass substrate 10 in the region of the optical functional chip 20 can be guaranteed, avoiding wiring breakage problems caused by height differences, thereby achieving reliable electrical interconnection.

[0026] In some embodiments, at least a portion of the bottom and surrounding area of ​​the optical functional chip 20 is filled and bonded using UV-curable optical adhesive 80. The UV-curable optical adhesive 80 can be an optically transparent adhesive with a refractive index matching that of the glass substrate 10. After curing, its light transmittance meets optical transmission requirements, thereby achieving stable fixation of the optical functional chip 20 within the glass substrate 10 while ensuring both optical and mechanical reliability. It is worth noting that the filling thickness of the UV-curable optical adhesive 80 should be controlled within an appropriate range to ensure bonding strength while avoiding thermal expansion mismatch caused by excessive adhesive layer thickness.

[0027] In some embodiments, the optical functional chip 20 may integrate a waveguide structure 21, an end-face coupler, an optical modulator, a photodetector, and wavelength division multiplexing (WDM) and deWDM structures (not shown in the figure). As an example, the waveguide structure 21 may employ a high refractive index difference material system, such as silicon (SOI), silicon nitride, or lithium niobate, with transmission loss meeting application requirements; the optical modulator includes a Mach-Zehnder modulator and / or a microring modulator, with modulation bandwidth supporting high-speed signal modulation; the WDM and deWDM structures include an arrayed waveguide grating and / or a microring resonator, with the number of channels configurable according to application requirements and channel spacing conforming to relevant standards. Notably, the optical functional chip 20 does not integrate a laser source; its light source signal is provided by an external pluggable laser. This design separates the heat source from the optical engine body, facilitating thermal management and enabling easy field replacement and maintenance of the laser.

[0028] In some embodiments, a glass waveguide 11 formed inside the glass substrate 10 using a laser direct-writing process is used to carry optical signal transmission. The glass waveguide 11 is optically coupled to the waveguide structure 21 in the optical functional chip 20 via end-face coupling. End-face coupling structures have advantages such as polarization insensitivity, large bandwidth, and large alignment tolerance, making them more suitable for multi-channel parallel optical interconnect applications compared to grating coupling. Preferably, the glass waveguide 11 is height-aligned with the waveguide structure 21 within the optical functional chip 20, thereby achieving low insertion loss optical signal coupling. Using the end-face coupling structure of this invention, the coupling loss between the glass waveguide 11 and the optical functional chip 20 can be controlled at a low level, significantly better than the loss level of traditional grating coupling.

[0029] To further reduce optical coupling loss, the sidewalls of the cavity 12 inside the glass substrate 10 can be optically polished to improve the optical quality of the end-face coupling interface. For example, an appropriate polishing process can be used to reduce the surface roughness of the sidewalls of the cavity 12 to a low level (i.e., a preset threshold), ensuring the optical quality of the light waveguide emission surface. The preset threshold can be set according to specific circumstances. Simultaneously, the sidewalls of the cavity 12 maintain good perpendicularity to ensure the parallelism between the light waveguide emission surface and the chip incident surface.

[0030] Please continue reading. Figure 1 The electrical functional chip 30 is disposed on the upper end of the glass substrate 10 and flip-chip bonded to the first redistribution layer 61 on the upper end of the glass substrate 10 via microbumps 71. The microbumps 71 can be copper pillars or solder bump structures, and the bump spacing can be designed according to the interconnect density requirements to achieve high-density electrical connections. In some embodiments, the electrical functional chip 30 is underfilled and encapsulated with epoxy resin to improve the mechanical strength and environmental reliability of the device. Preferably, the coefficient of thermal expansion of the epoxy resin matches that of the solder, which can effectively alleviate thermal stress during thermal cycling.

[0031] In this embodiment, the electrical functional chip 30 and the optical functional chip 20 are stacked, enabling them to achieve the shortest possible electrical interconnection in the vertical direction. This significantly shortens the interconnection path length, effectively reducing parasitic inductance, parasitic capacitance, and transmission delay, and improving high-frequency signal transmission performance. Compared to a planar layout, the stacked layout is beneficial for increasing signal transmission rate and reducing power consumption.

[0032] In some embodiments, the electrical functional chip 30 internally includes a driving circuit module for driving an optical modulator and a transimpedance amplifier circuit module (not shown) for receiving signals from a photodetector. As an example, the driving circuit module can employ a differential structure, providing adjustable modulation and bias currents to adapt to the operating point requirements of different optical modulators; the transimpedance amplifier circuit module can employ a feedback resistor-adjustable structure, with gain and bandwidth meeting the requirements for high-speed signal reception. Both the driving circuit module and the transimpedance amplifier circuit module possess a certain degree of linear equalization, which can compensate for the attenuation of high-frequency signals in the transmission link, achieving high-quality conversion between high-speed electrical signals and optical signals.

[0033] Please continue reading. Figure 1 To achieve electrical interconnection, a first redistribution layer 61 is provided on the first surface, and a second redistribution layer 62 is provided on the second surface. The first redistribution layer 61 may be formed in the first dielectric layer 91, and the second redistribution layer 62 may be formed in the second dielectric layer 92. The first dielectric layer 91 and the second dielectric layer 92 are used to protect the redistribution layers from mechanical damage, moisture, and chemical contamination, and may be made of materials such as silicon nitride, silicon oxide, or polyimide, with a thickness sufficient to provide effective protection.

[0034] The electrical functional chip 30 is electrically connected to the first wiring layer 61 via multiple microbumps 71. The first wiring layer 61 employs a multi-layer metal wiring structure; the conductive layer can be made of copper or gold, and the line width and spacing can be designed according to wiring density requirements to achieve high-density wiring. In some embodiments, the first wiring layer 61 not only provides interconnection between the electrical functional chip 30 and the optical functional chip 20, but also provides power distribution and a ground plane to ensure signal integrity. The second wiring layer 62 has a similar structure to the first wiring layer 61.

[0035] Multiple parallel glass vias 13 are formed between the first and second surfaces. The glass vias 13 are filled with conductive material, and the first redistribution layer 61 and the second redistribution layer 62 are electrically connected through the conductive material. The second redistribution layer 62, the conductive material, and the first redistribution layer 61 form an electrical path for connecting the printed circuit board 40. Through this three-dimensional interconnect structure, signals from the optical functional chip 20 and the electrical functional chip 30 can be transmitted to the printed circuit board 40 via the shortest path, avoiding the long interconnect paths and high parasitic parameter problems associated with traditional wire bonding.

[0036] In this embodiment, the glass vias 13 inside the glass substrate 10 work in conjunction with the multilayer redistribution layers at the top and bottom ends of the glass substrate 10 to achieve high-density electrical interconnection between the optical functional chip 20, the electrical functional chip 30, and the external printed circuit board 40. The glass substrate 10 material has good electrical properties and dimensional stability, which is beneficial for reducing losses and crosstalk during high-frequency signal transmission. Experimental results show that, under high-frequency conditions, the signal transmission loss through the glass vias and redistribution layers can be controlled at a low level, which is superior to that of traditional organic substrates.

[0037] A ball grid array 72 is also formed on the second surface. The ball grid array 72 can be made of, for example, lead-free solder, and the size and spacing of the solder balls can be matched to the pad design of the printed circuit board 40. The printed circuit board 40 is electrically connected to the second redistribution layer 62 via the ball grid array 72. The entire three-dimensional packaged optical engine 100 is soldered to the printed circuit board 40 via the ball grid array 72 formed by solder ball bumps at the lower end of the glass substrate 10, using standard surface mount technology. This allows for high-density electrical interface connections with system-level circuits, suitable for optoelectronic co-packaging and large-scale integrated communication interconnect applications. The ball grid array 72 not only provides electrical connections but also serves as mechanical support and heat dissipation. In some embodiments, hot solder balls can be provided in the ball grid array 72 to enhance heat dissipation.

[0038] Please continue reading. Figure 1 The optical signal input and output of the 3D encapsulated optical engine 100 are achieved through a multi-channel fiber optic connector 50. The fiber optic connector 50 supports multi-channel parallel optical interconnection. Continuous laser light sources and modulated optical signals enter and exit the 3D encapsulated optical engine 100 through the multi-channel fiber optic connector 50 to meet the requirements of multi-channel, high-bandwidth-density optical interconnection. Specifically, the fiber optic connector 50 connects the glass optical waveguide 11 and the external optical fiber 51, used to input the laser from the external optical fiber 51 into the 3D encapsulated optical engine 100, or to output the modulated optical signal from the 3D encapsulated optical engine 100 to the external optical fiber 51. The fiber optic connector 50 can be fixed to the glass substrate 10 using UV adhesive to ensure long-term mechanical reliability.

[0039] Through the above structural design, this invention leverages the advantages of glass substrates, such as high flatness, low RF loss, high via density, and support for optical waveguide fabrication. The proposed three-dimensional encapsulated optical engine based on a glass substrate achieves flexible, low-loss optical coupling while ensuring high-frequency electrical interconnect performance, exhibiting excellent scalability and integration potential. This invention is suitable for high-speed optical interconnect scenarios in future multi-chip and ultra-large-scale integrated systems, and has broad application prospects in high-performance computing, data centers, artificial intelligence accelerators, 5G / 6G communications, aerospace, and other fields.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A three-dimensional encapsulated optical engine based on a glass substrate, characterized in that, include: A glass substrate includes a first surface and a second surface opposite to each other, a cavity extending through the glass substrate is formed between the first surface and the second surface, and a glass waveguide located inside the glass substrate, a first end of the glass waveguide extending into the cavity, and a second end of the glass waveguide being used for coupling connection with an external optical fiber. An optical functional chip is embedded and fixed in the cavity, and the optical functional chip is optically coupled to the first end of the glass optical waveguide; An electrical functional chip is disposed on the first surface and is electrically connected to the optical functional chip; The second surface of the glass substrate is used for electrical connection with the printed circuit board, so that the optical functional chip and the electrical functional chip are electrically connected to the printed circuit board through the glass substrate.

2. The three-dimensional encapsulated optical engine according to claim 1, characterized in that, A first wiring layer is provided on the first surface, and the electrical functional chip is electrically connected to the optical functional chip through the first wiring layer; A second rewiring layer is provided on the second surface, and a plurality of parallel glass vias are formed between the first surface and the second surface. The glass vias are filled with conductive material, and the first rewiring layer and the second rewiring layer are electrically connected through the conductive material. The second redistribution layer, the conductive material, and the first redistribution layer form an electrical path for connecting the printed circuit board.

3. The three-dimensional encapsulated optical engine according to claim 2, characterized in that, Multiple microbumps are also formed on the first surface. The electrical functional chip is flip-chip bonded to the glass substrate through the multiple microbumps and is electrically connected to the first redistribution layer.

4. The three-dimensional encapsulated optical engine according to claim 2, characterized in that, A ball grid array is also formed on the second surface. The printed circuit board is soldered to the three-dimensional packaged optical engine through the ball grid array and electrically connected to the second redistribution layer.

5. The three-dimensional encapsulated optical engine according to claim 1, characterized in that, The thickness of the glass substrate is greater than or equal to the thickness of the optical functional chip, and the upper surface of the optical functional chip is flush with the first surface.

6. The three-dimensional encapsulated optical engine according to claim 5, characterized in that, At least a portion of the side and bottom surfaces of the optical functional chip are filled and bonded to the glass substrate using UV-curable optical adhesive.

7. The three-dimensional encapsulated optical engine according to claim 1, characterized in that, The optical functional chip includes a waveguide structure coupled to the glass optical waveguide, and the waveguide structure and the glass optical waveguide are located at the same height.

8. The three-dimensional encapsulated optical engine according to claim 1, characterized in that, The roughness of the sidewall region of the cavity located between the optical functional chip and the glass waveguide is lower than a preset threshold.

9. The three-dimensional encapsulated optical engine according to claim 1, characterized in that, The electrical functional chip and the optical functional chip are stacked together.

10. The three-dimensional encapsulated optical engine according to claim 1, characterized in that, Also includes: An optical fiber connector connects the glass waveguide and the external optical fiber, and is used to input the laser from the external optical fiber into the three-dimensional encapsulated optical engine, or to output the laser from the three-dimensional encapsulated optical engine to the external optical fiber.

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