Optical chip optical fiber coupling packaging framework and process for photoelectric co-packaging

Abstract

The invention relates to the technical field of photoelectric co-packaging, in particular to an optical chip optical fiber coupling packaging framework and process for photoelectric co-packaging. In the optical chip and adapter plate vertical mounting system, n + 2 continuous V-shaped grooves are etched in the position, corresponding to an end face coupler, of the bottom of an adapter plate, the two V-shaped grooves in the two sides are used for arranging limiting optical fibers, the n V-shaped grooves in the middle are used for containing and guiding optical fibers, and n is larger than or equal to 1; passive alignment of coupling of the optical fiber and the optical chip, high process compatibility and high mechanical stability are achieved. According to the invention, the optical chip does not need to be installed at the edge of the adapter plate of the photoelectric co-packaging system any more, the feasibility of vertical stacking is greatly expanded, a solution is provided for the installation of the optical bridge chip in the three-dimensional stacked photoelectric co-packaging system, and a more compact structure becomes possible under the condition of using optical fiber edge coupling.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic co-packaging, and in particular to an optical chip fiber-coupled packaging architecture and process for optoelectronic co-packaging. Background Art

[0002] With the rapid development of technologies such as cloud computing, artificial intelligence, and big data, data center traffic has surged, requiring higher-bandwidth network connections. Traditional electrical interconnection and communication technologies have reached a bottleneck, leading to the development of optical-to-electrical (CPO) co-packaging technology, which aims to replace electricity with light as the information transmission medium, thereby reducing power consumption and improving system performance and bandwidth density.

[0003] In CPO technology, fiber coupling is the key technology for realizing optical signal input and output. Among various fiber coupling technologies, modular fiber array coupling technology is an important technology. However, the current modular fiber array coupling technology has many disadvantages such as difficulty in alignment and poor process compatibility. Therefore, the development of new modular fiber array coupling technology has been put on the agenda.

[0004] Existing fiber coupling technologies mainly include end-face coupling (edge ​​coupling) achieved by aligning the optical fiber with the on-chip optical waveguide, and grating coupling (vertical coupling) in which the optical fiber is coupled to the optical chip in the vertical direction through a grating. Among them, the vertical coupling technical solution has the advantages of convenient testing, good process compatibility, and short signal path, but it also has disadvantages such as large coupling loss, polarization sensitivity, large packaging structure size, and small coupling wavelength bandwidth. The edge coupling technical solution has the advantages of flexible design, low insertion loss, and simple process; however, the traditional end-face coupling process has a large overall thickness, even up to millimeter level, because the modular fiber array requires upper and lower cover plates to fix it, resulting in an inability to align the optical chip and FA (fiber array) in height. Therefore, the optical chip can only be placed on the edge of the packaging carrier traditionally.

[0005] However, the fixed positions of the optical chip and the adapter plate in the optoelectronic co-package CPO are not in the edge area, which will result in the traditional end-face coupling technology being unable to be applied to the CPO technology. Summary of the Invention

[0006] In view of the above-mentioned problems or deficiencies, and to solve the problem that the existing fiber end face coupling technology is not suitable for CPO technology, the present invention provides an optical chip fiber coupling packaging architecture and process for optoelectronic co-packaging.

[0007] An optical chip fiber coupling packaging architecture for optoelectronic co-packaging includes: an adapter plate, an optical chip, an end coupler, a limiting optical fiber, a V-groove array, an electrical chip and a packaging substrate.

[0008] The adapter plate (such as a glass adapter plate) is used to integrate the package with the optical chip and the electrical chip, and realize optical and electrical communication;

[0009] After the end coupler of the optical waveguide on each optical chip is integrated with the adapter plate, a continuous n+2 V-grooves are etched on the adapter plate to form a V-groove array, based on the width of the end coupler (corresponding to the width of the fiber array). The n middle V-grooves are adaptively aligned with the end coupler on the optical chip to accommodate the fiber array, and the size of a single V-groove is adapted to the size of a single fiber. The number of fiber arrays corresponds to the number of V-grooves, n, where n ≥ 1. The two V-grooves on either side of the V-groove array are used to install the corresponding limit fibers.

[0010] Furthermore, the limiting optical fiber is installed and fixed using ultraviolet curing glue.

[0011] Furthermore, the V-groove is prepared by wet etching or dry etching.

[0012] Furthermore, the optical waveguide on the optical chip is an integrated optical waveguide of silicon, silicon nitride, silicon germanium, silicon dioxide, or a Group III-V compound (such as indium phosphide).

[0013] Furthermore, the optical waveguide on the optical chip is a rectangular waveguide, a ridge waveguide or a diffused waveguide.

[0014] The process flow of the optical chip fiber-coupled packaging architecture for optoelectronic co-packaging is as follows:

[0015] After the optical chip is hybrid-bonded under the adapter plate, the optical chip-adapter plate system is then soldered to the packaging substrate through reflow soldering; the limiting optical fibers installed on both sides of the V-groove array naturally play a limiting role after reflow soldering, reserving installation space for the optical fiber array between the adapter plate and the packaging substrate, and because the n V-grooves in the middle are adapted to the optical fiber array in both number and size, passive alignment is easy.

[0016] Furthermore, the reflow soldering uses BGA solder balls whose diameter matches the diameter of the optical fiber.

[0017] In the optoelectronic co-packaging system of the present invention, it is necessary to hybrid bond the optical chip under the adapter plate, and then solder the system consisting of the optical chip and adapter plate to the packaging substrate through reflow soldering. If the optical chip is installed at a non-edge position of the substrate in the optoelectronic co-packaging system of the present invention, as mentioned above, due to the size of the FA, it is necessary to reserve sufficient spacing between the adapter plate and the packaging substrate to install the FA; that is, using large-sized BGA solder balls to make the spacing between the adapter plate and the packaging substrate not less than the thickness of the FA, however, since the BGA solder balls are usually less than 150um, even if larger solder balls can be achieved technically, challenges such as thermal reliability of the package and signal integrity are faced, so the optical chip needs to be placed at the edge of the entire packaging system; however, for the optical bridge chip in the optoelectronic co-packaging, due to its functional limitations, it cannot be installed at the edge.

[0018] The present invention innovatively proposes to etch continuous n+2 V-grooves on the bottom of the adapter plate in the vertical mounting system of the optical chip and the adapter plate to place and guide the optical fiber, thereby achieving passive alignment of the optical fiber and the optical chip coupling, high process compatibility, and high mechanical stability. This makes it possible for the optical chip to no longer have to be installed at the edge of the optoelectronic co-packaging system, greatly expanding the feasibility of vertical stacking, and proposing a solution for the installation of optical bridge chips in three-dimensional stacked optoelectronic co-packaging systems, making a more compact structure possible when using optical fiber edge coupling.

[0019] The beneficial effects brought by the present invention are:

[0020] 1. Compared with traditional edge coupling solutions, optical chips no longer need to be installed at the edge of the optoelectronic co-packaging system, greatly expanding the feasibility of vertical stacking. The architecture proposed in this invention can be used in 2.5D and 3D packaging systems, making the entire packaging system structure more compact.

[0021] 2. Compared with the traditional edge coupling solution, the position of the fiber coupling process in the present invention in the entire packaging process is more flexible. It can be placed after high-temperature processes such as reflow soldering, so that the optoelectronic co-packaging system with high-temperature processes does not need to use high-temperature resistant UV curing adhesive, and the process compatibility is better.

[0022] 3. Compared with the traditional edge coupling solution, the present invention can achieve passive alignment because the optical fiber is guided by the V-groove, solving the problem of difficult edge coupling alignment.

[0023] 4. Compared with the traditional edge coupling solution, the V-groove array architecture proposed in the present invention can provide better fixation for the optical fiber, improve the mechanical stability of the optical fiber fixed on the substrate, and improve the system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a schematic cross-sectional side view of the V-groove array of the present invention.

[0025] Figure 2 It is a schematic front view of the cross section of the V-groove array of the present invention.

[0026] Figure 3 Schematic diagram of the optical bridge structure of the V-groove array in the embodiment.

[0027] Figure 4 It is a schematic diagram of an enlarged partial cross-section side view of the V-groove array of the embodiment.

[0028] Figure 5 It is a partial cross-sectional front view schematic diagram of the V-groove array of the embodiment.

[0029] Figure numerals: (1) glass adapter plate, (2) optical chip, (3) end coupler, (301) end coupler tip waveguide core layer, (302) end coupler tip waveguide cladding layer, (4) optical fiber, (401) optical fiber core layer, (402) optical fiber cladding layer, (5) V-groove array, (6) electrical chip, (7) BGA solder ball, (8) package substrate through hole, (9) package substrate. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] The overall structure of this embodiment is shown in Figure (3). A V-groove array (5) consisting of six V-grooves with a groove width of 130 μm and a groove depth of 70 μm is etched on the glass substrate (1). Then, the glass adapter plate (1) and the optical chip (2) are hybrid-bonded together. The center of the tip of the end face coupler (3) on the optical chip (2) is 5 μm away from the chip surface and aligned with the four V-grooves in the center of the V-groove array (5). UV curing glue is applied to the V-grooves on both sides of the V-groove array (5). A short optical fiber with a diameter of 150 μm is installed using the UV curing glue (pay attention to the amount of curing glue used during the installation process to prevent the thickness of the curing glue overflowing the V-groove from exceeding the thickness of the optical fiber above the V-groove, resulting in an impact on the limiting function of the limiting optical fiber or poor BGA soldering during the reflow soldering process); then, this system is soldered to the packaging substrate (9) using reflow soldering, and the limiting optical fiber can leave a space suitable for installing the optical fiber between the glass substrate and the packaging substrate.

[0032] Figure 4 FIG. 1 is a schematic diagram of a partial cross-section and an enlarged side view of a V-groove array corresponding to an end face coupler in this embodiment. Figure 5 This is a schematic diagram of a partial cross-section of the V-groove array corresponding to the end face coupler.

[0033] like Figure 1As shown, for the architectural requirements of optoelectronic co-packaging, the glass adapter plate (1) and the optical chip (2) are hybrid-bonded together to achieve three-dimensional stacking of the optical chip and the electrical chip. In this case, the installation and coupling of the optical fiber (4) will become more difficult, especially because the UV-curing adhesive commonly used for installing and fixing the optical fiber cannot withstand the high temperature in processes such as reflow soldering, resulting in poor process compatibility; when aligning the optical fiber and the optical waveguide (3), it is easy to offset, increasing the coupling loss; using only UV-curing adhesive for fixation also has hidden dangers in mechanical stability; and due to the FA thickness problem, when the optical chip (2) is not at the edge of the glass adapter plate (1), the FA cannot be installed between the glass adapter plate and the packaging substrate, and the optical fiber (4) cannot be aligned with the end face coupler (3) on the optical chip (1).

[0034] The present invention etches a V-groove array (5) consisting of n+2 V-grooves on the bottom of a glass adapter plate (1) and sets a limiting optical fiber, thereby enhancing the passive alignment capability of optical fiber coupling through a simple step; the V-groove array (5) adds an additional rigid limit to the optical fiber, thereby improving the mechanical stability of the system.

[0035] When the V-groove array (5) structure is used, the optical fiber can be installed in the aligned V-groove array after reflow soldering, without having to use high-temperature resistant curing glue to install the optical fiber before reflow soldering, so that the process of the present invention is compatible with the high-temperature process and no longer relies on high-temperature resistant curing glue, thereby improving process compatibility; unlike the traditional coupling structure that requires the optical chip to be installed at the edge, the V-groove array (5) structure allows the optical chip to no longer have to be installed at the edge of the optoelectronic co-packaging system, greatly expanding the feasibility of vertical stacking, and proposing a solution for the installation of optical bridge chips in a three-dimensionally stacked optoelectronic co-packaging system, making the structure of the optoelectronic co-packaging system more compact.

[0036] As can be seen from the above embodiments, the present invention innovatively proposes that in a vertical mounting system for an optical chip and an adapter plate, n+2 continuous V-grooves are etched at the bottom of the adapter plate at positions corresponding to the end couplers, and the two V-grooves on both sides are used to set limiting optical fibers, while the n V-grooves in the middle are used to place and guide optical fibers, thereby achieving passive alignment of the optical fiber and optical chip coupling, high process compatibility, and high mechanical stability. The present invention eliminates the need for optical chips to be mounted on the edge of the adapter plate in an optoelectronic co-packaging system, greatly expanding the feasibility of vertical stacking and providing a solution for the installation of optical bridge chips in a three-dimensionally stacked optoelectronic co-packaging system, making a more compact structure possible when using optical fiber edge coupling.

Claims

1. An optical chip fiber-coupled packaging architecture for optoelectronic co-packaging, comprising an adapter plate, an optical chip, an end coupler, an electrical chip, and a packaging substrate, characterized in that: It also includes position-limiting optical fibers and V-groove arrays; The adapter board is used to integrate the package with the optical chip and the electrical chip, and realize optical and electrical communication; Among them, after the end face coupler of the optical waveguide on each optical chip is integrated with the adapter plate, a continuous n+2 V-grooves are etched on the corresponding position on the adapter plate, based on the width of the end face coupler to form a V-groove array. The n middle V-grooves are adaptively aligned with the end face coupler on the optical chip to place the optical fiber array, and the size of a single V-groove is adapted to the size of a single optical fiber. The number of optical fiber arrays corresponds to the number n of V-grooves, n≥1; the two V-grooves located on both sides of the V-groove array are respectively installed and fixed with limited optical fibers.

2. The optical chip fiber-coupled packaging architecture for optoelectronic co-packaging according to claim 1, characterized in that: The limiting optical fiber is installed and fixed using ultraviolet curing glue.

3. The optical chip fiber-coupled packaging architecture for optoelectronic co-packaging according to claim 1, characterized in that: The V-shaped groove is prepared by wet etching or dry etching.

4. The optical chip fiber-coupled packaging architecture for optoelectronic co-packaging according to claim 1, characterized in that: The adapter plate is a glass adapter plate.

5. The optical chip fiber-coupled packaging architecture for optoelectronic co-packaging according to claim 1, characterized in that: The optical waveguide on the optical chip is a rectangular waveguide, a ridge waveguide or a diffused waveguide.

6. The optical chip fiber-coupled packaging architecture for optoelectronic co-packaging according to claim 1, characterized in that: The optical waveguide on the optical chip is an integrated optical waveguide of silicon, silicon nitride, silicon germanium, silicon dioxide, or a III-V main group compound.

7. The optical chip fiber-coupled packaging architecture for optoelectronic co-packaging according to claim 1, characterized in that: The process flow is: after hybrid bonding the optical chip under the adapter board, the optical chip-adapter board system is soldered to the packaging substrate through reflow soldering.

8. The optical chip fiber-coupled packaging architecture for optoelectronic co-packaging according to claim 7, characterized in that: The reflow soldering uses BGA solder balls with a diameter matching the diameter of the optical fiber.

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