Glass adapter plate photoelectric co-interconnection packaging framework and process

Abstract

The invention belongs to the field of semiconductor photoelectric chip packaging, and particularly relates to a glass adapter plate photoelectric common interconnection packaging framework and process. According to the method, the inclined via holes are formed in the glass adapter plate, so that the inclined and vertical via holes can be prepared by using the wedge-shaped transparent medium under the condition of not replacing equipment, and the processing cost is greatly reduced. The design of the inclined via hole has a passive limiting effect, supports passive alignment coupling, perfectly accords with the inclination angle coupling principle of the grating coupler, does not need an additional optical fiber array cover plate clamp, reduces the packaging cost, and improves the packaging compactness. Optical fiber coupling packaging is arranged in the final process and is not affected by the high-temperature flip-chip reflow soldering technology, and the technology is highly compatible. According to the invention, the size of the optical fiber array is effectively reduced, the packaging structure is simplified, the compactness and process flexibility of photoelectric co-packaging are improved, and the method is suitable for the application fields with high bandwidth and low delay requirements, such as data centers, AI calculation and high-performance calculation.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor optoelectronic chip packaging, and in particular relates to a glass transfer plate optoelectronic interconnection packaging architecture and process. Background Art

[0002] With the rapid development of technologies such as 5G communications, artificial intelligence (AI), and high-performance computing (HPC), data centers and computing centers are placing higher demands on chip packaging technology, particularly in the areas of co-packaged optics (CPO) and optical interconnects. Traditional 2.5D and 3D packaging technologies rely primarily on interposers to achieve high-density electrical interconnects. However, in hybrid optoelectronic packaging, the fiber coupling requirements of optical chips often struggle to accommodate interposer packaging architectures, resulting in complex packaging structures, difficult processes, increased size, and increased costs.

[0003] In 2.5D or 3D optoelectronic co-packaging, the optical chip is flipped on the adapter board. In order to achieve the coupling packaging of the optical chip grating coupler and the optical fiber, there are two conventional methods: 1. grooving the adapter board and 2. back coupling technology.

[0004] Adapter plate slotting: This involves removing the adapter plate in the grating coupling area to form a rectangular through-hole. The length and width of the rectangular hole must be larger than the cover plate dimensions of the fiber array. This allows the fiber array to be inserted into the rectangular through-hole and contact the optical chip surface, achieving high-efficiency fiber coupling. This method results in a large opening in the glass adapter plate, which reduces the reliability of the adapter plate structure and significantly increases the package size. Furthermore, the fiber array coupling can only use an inefficient active alignment process, resulting in low packaging efficiency.

[0005] Back-coupling technology involves thinning the optical chip substrate to allow optical fiber coupling to the grating coupler from the back of the chip. This method faces several technical challenges: 1. High-quality back-thinning technology; 2. The grating requires a metal reflector on the top surface of the chip to redirect the diffracted light backward. Overall, this method has extremely high process complexity and packaging costs.

[0006] In summary, in the current context of optoelectronic co-packaging (CPO), there is an urgent need for a compatible adapter board packaging architecture and process that meets the requirements of optical chip fiber coupling. Summary of the Invention

[0007] In view of the above-mentioned problems or deficiencies, and to solve the problem of poor compatibility between optical fiber coupling and adapter plates in optoelectronic interconnection packaging, the present invention provides a glass adapter plate optoelectronic interconnection packaging architecture and process.

[0008] A glass adapter plate optoelectronic interconnection packaging architecture comprises a glass adapter plate, an optical chip, a packaging substrate, an electrical chip and an optical fiber.

[0009] The glass adapter board is provided with inclined vias, vertical vias and vertical via conductive posts.

[0010] Among them, after the vertical via is filled with a conductive material, a vertical via conductive post is formed, which is used as an electrical connection channel between the upper and lower layers of the glass adapter board.

[0011] The inclined vias are arranged in the grating coupling area. The aperture of the inclined vias is adapted to the diameter of the optical fiber. After the glass adapter board, the optical chip, the packaging substrate and the electrical chip are fixed, the optical fiber passes through the inclined vias and is aligned and contacted with the grating on the surface of the optical chip to realize the optical coupling between the optical fiber and the optical chip.

[0012] Furthermore, the optical chip is embedded in the packaging substrate. The surface electrode pads of the packaging substrate and the surface of the optical chip are on the same side and the surface pads are at the same horizontal height. The glass adapter board is packaged on the packaging substrate through a solder ball array and filled with underfill. The electrical chip is packaged on the upper surface of the glass adapter board through a flip-chip bonding process. The glass adapter board is provided with a plurality of vertical via conductive posts and inclined vias. The aperture of the inclined vias is larger than the diameter of the optical fiber. The optical fiber is inserted into the inclined vias and contacts the surface of the optical chip to be aligned with the grating coupler.

[0013] The present invention innovatively proposes an optoelectronic composite glass adapter board with grating coupling inclined angle vias and electrical interconnection vias, realizing the integrated interconnection of optical signals and electrical signals, and effectively improving the packaging integration and performance.

[0014] Furthermore, the number of the inclined vias is n, n≥2; and adjacent inclined vias do not intersect each other.

[0015] Furthermore, the inclined vias are generated by using a vertical laser source, utilizing the refraction effect of a wedge-shaped transparent medium, and after refraction, the laser beam is incident on the glass adapter board at an inclined angle, and by using a laser-induced etching technology; wherein the wedge-shaped transparent medium is not damaged by the laser beam.

[0016] Furthermore, the size of the glass adapter board is panel-level or wafer-level, and the size of the wedge-shaped transparent medium is panel-level or wafer-level.

[0017] Furthermore, the wedge-shaped transparent medium is provided with an integrated periodic wedge-shaped unit on the surface of the wedge-shaped transparent medium to realize large-scale precise preparation when n≥2.

[0018] Design and application of the wedge-shaped transparent medium: The present invention innovatively introduces a wedge-shaped transparent medium on the surface of the glass substrate. By changing the incident angle of the light beam, the vertical light beam is converted into an inclined light beam, thereby realizing the high-precision preparation of the glass inclined vias; and provides a technical means for batch and large-scale precise preparation, so that the present invention can also cope with ease in the face of the demand scenario of an optical fiber array.

[0019] Furthermore, the refraction effect of the wedge-shaped transparent medium satisfies the following relationship:

[0020] sin(α) = N * sin(β), N * sin(α - β) = sin(θ)

[0021] where N is the refractive index of the wedge-shaped transparent medium, α is the angle between the inclined surface of the wedge-shaped transparent medium and the horizontal direction (the surface of the glass adapter board), the laser beam light source is perpendicular to the surface of the glass adapter board, β is the refraction angle after the laser beam enters the wedge-shaped transparent medium, and θ is the angle between the inclined via hole and the vertical direction.

[0022] Furthermore, the gap between the optical fiber and the grating coupler is filled with a refractive index matching liquid, which is used to improve the optical coupling efficiency and fix the optical fiber at the same time.

[0023] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Equipment compatibility and cost advantages: Traditional glass via hole TGV laser processing equipment only supports vertical beam exposure, and the TGV is also a vertical via hole. The solution of the present invention can realize the preparation of inclined and vertical via holes by using a wedge-shaped transparent medium without replacing the equipment, greatly reducing the processing cost and improving the process flexibility.

[0025] 2. High-efficiency optical coupling: Since the grating coupler is realized by using the grating diffraction principle, the diffracted light needs to have a certain inclination angle. Therefore, in order to achieve efficient coupling between the optical fiber and the grating coupler, the optical fiber usually needs to be inclined at 8 degrees or 10 degrees. Although traditional optical fiber arrays can achieve 8-degree or 10-degree optical fiber end faces by grinding and polishing and be perfectly coupled with the grating of the optical chip, the packaging of the optical fiber array depends on active alignment and large-size optical fiber arrays, and the optical fiber array is attached with a large fixed cover plate, resulting in low packaging efficiency, high packaging cost, and large packaging size. Inserting multiple single-mode optical fibers into traditional 90-degree vertical glass through holes can eliminate the cover plate of the optical fiber array and improve the packaging compactness of the optical fiber, but the 90-degree vertical optical fiber will cause light reflection at the optical fiber end face and low-efficiency coupling. In order to achieve high-channel density and high-efficiency passive alignment coupling of optical fibers on the glass adapter board, the present invention directly inserts n (n≥2) single-mode optical fibers into the inclined via holes of the glass adapter board to realize multi-channel optical fiber coupling packaging. The passive limit of the inclined via hole ensures the accuracy of the optical fiber position, supports passive alignment coupling, eliminates the need for additional cover plate fixtures for the optical fiber array, reduces the packaging cost, shrinks the packaging size, and improves the packaging compactness. At the same time, compared with the optical fiber in the 90-degree vertical via hole, inserting the optical fiber into the inclined via hole can achieve more efficient coupling with the grating coupler, significantly improving the optical coupling efficiency and signal transmission quality.

[0026] 3. Process Compatibility and Stability: In the optoelectronic co-packaging architecture of the present invention, since the fiber optic coupling packaging is arranged in the last process, the high-temperature flip-chip reflow soldering will not affect the coupling stability between the optical fiber and the optical chip, ensuring high compatibility of the optoelectronic co-packaging process and improving the overall packaging reliability and manufacturing flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic process flow diagram for preparing optical and electrical vias on the glass interposer of the present invention.

[0028] Figure 2 It is a schematic diagram of the angular relationship of the inclined optical vias on the glass interposer of the present invention.

[0029] Figure 3 It is a schematic diagram of the process principle for preparing the inclined optical vias on the glass interposer in Example 2.

[0030] Figure 4 It is a schematic diagram of the optoelectronic co-interconnection packaging architecture of the glass interposer in Example 1.

[0031] Figure 5 It is a schematic diagram of the optoelectronic co-interconnection packaging architecture of the glass interposer in Example 2.

[0032] Reference Numerals: 1 - glass interposer, 2 - optical chip, 3 - packaging substrate, 4 - electrical chip, 5 - underfill, 6 - refractive index matching liquid, 7 - grating coupler, 8 - optical fiber, 9 - inclined via, 10 - vertical via conductive post, 11 - vertical via, 12 - wedge-shaped transparent medium. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The present invention will be further described in detail below with reference to the drawings and embodiments.

[0034] Example 1:

[0035] As Figure 4 shown, the optical chip (2) is a silicon optical chip, the packaging substrate (3) is an 8-layer organic substrate with a redistribution circuit provided inside, and a 750-um-thick groove is provided in the center of the substrate for placing the optical chip. The thickness of the glass interposer (1) is 200 um, and the vertical vias and inclined vias adopt Figure 1Processed by the process shown, the laser is a CO2 laser with a wavelength of 10.6 μm, and the material of the wedge-shaped transparent medium surface is Si. The glass adapter board (1) includes a plurality of vertical via conductive copper pillars with a diameter of 25 μm, a row of 4 inclined vias with a pitch of 250 μm, and the diameter of the inclined vias is 126 μm. One electrical chip (4) is flip-chip packaged on the upper surface of the glass adapter board, and the glass adapter board (1) is packaged on the packaging substrate (3) through a solder ball array. The underfill (5) is made of epoxy resin. Single-mode optical fibers with a diameter of 125 μm and an end face angle of 8 degrees are inserted into each inclined via (9) of the glass adapter board. The end face of the optical fiber is flush with the surface of the optical chip, and the gap between them is filled and fixed with external curing glue.

[0036] Example 2:

[0037] As Figure 4 shown, the optical chip (2) is a silicon optical chip, the packaging substrate (3) is an 8-layer organic substrate with a redistribution circuit provided inside, and a groove with a thickness of 300 μm is provided in the center of the substrate for placing the optical chip. The thickness of the glass adapter board (1) is 300 μm, and the vertical vias and inclined vias are processed by the Figure 1 process shown. The laser is a CO2 laser with a wavelength of 10.6 μm, but the wedge-shaped transparent medium surface adopts an integral periodic wedge surface as Figure 3 shown, and the material is Si. The glass adapter board (1) includes a plurality of vertical via conductive copper pillars with a diameter of 25 μm, a row of 4 inclined vias with a pitch of 250 μm, and the via diameter is 126 μm. One electrical chip (4) is flip-chip packaged on the upper surface of the glass adapter board, and the glass adapter board (1) is packaged on the packaging substrate (3) through a solder ball array. The underfill (5) is made of epoxy resin. Single-mode optical fibers with a diameter of 125 μm and an end face angle of 8 degrees are inserted into each inclined via of the glass adapter board. The end face of the optical fiber is flush with the surface of the optical chip, and the gap between them is filled and fixed with external curing glue.

[0038] Example 3:

[0039] As Figure 5 shown, the optical chip (2) is a silicon optical chip, the packaging substrate (3) is an 8-layer organic substrate with a redistribution circuit provided inside, and a groove with a thickness of 300 μm is provided in the center of the substrate for placing the optical chip. The thickness of the glass adapter board (1) is 300 μm, and the vertical vias and inclined vias are processed by the Figure 1 process shown. The laser is a CO2 laser with a wavelength of 10.6 μm, but the wedge-shaped transparent medium surface adopts an integral periodic wedge surface as Figure 3The shown integral periodic wedge-shaped surface is made of Si. The glass adapter board (1) includes multiple vertical via conductive copper pillars with a diameter of 25 um, two columns of inclined vias, each column containing 4 vias, the pitch of the inclined vias is 250 um, and the via diameter is 126 um. One electrical chip (4) is flip-chip packaged on the upper surface of the glass adapter board. The glass adapter board (1) is packaged on the package substrate (3) through a solder ball array, and the underfill (5) is made of epoxy resin. Single-mode optical fibers with a diameter of 125 um and an end face angle of 0 degrees are inserted into each inclined via of the glass adapter board. The included angle between the end face of the optical fiber and the surface of the optical chip is 8 degrees, and the gap between them is filled and fixed with an external curing adhesive.

[0040] In the application of photoelectric co-packaging, it is necessary to achieve electrical interconnection and fiber optic packaging simultaneously. Based on the glass adapter board, the present invention further designs inclined vias and their manufacturing process, enabling it to be compatible with the fiber optic coupling requirements of optical chips, and simplifying the packaging structure, process complexity, with small size and low cost. The basic principle of the inclined via manufacturing process is as Figure 1 shown: First, conventional vertical vias are prepared on the surface of the glass adapter board using a laser-induced etching process; then, a wedge-shaped transparent dielectric surface is placed between the laser source and the glass adapter board. Utilizing the principle of light refraction, the vertical laser source is inclined to enter the glass adapter board, and after exposure and etching, inclined vias are formed; finally, vertical via conductive pillars are formed through a copper filling process.

[0041] After the glass adapter board (1) is prepared, the packaging of the optoelectronic chips is completed using the packaging structure as Figure 4 shown: First, the optical chip is flip-chip packaged on one side of the glass adapter board, and the grating coupler of the optical chip is aligned with the inclined vias. Subsequently, the electrical chip is flip-chip packaged on the other side of the glass adapter board. The electrical chip, optical chip, and package substrate achieve electrical interconnection through the vertical via conductive pillars. The gap between the flip-chip solder balls is filled with an epoxy resin underfill to achieve high-strength structural support. Finally, the optical fiber is inserted into the inclined via, and the front end of the optical fiber touches the surface of the optical chip. The gaps between the optical fiber and the chip, and between the optical fiber and the glass adapter board are filled with an ultraviolet curing adhesive or other refractive index matching liquid to reduce light reflection and fix the optical fiber, realizing efficient fiber optic coupling. Thus, the high-efficiency fiber optic coupling packaging of the optical chip in the glass adapter board photoelectric co-packaging architecture is completed.

[0042] As can be seen from the above embodiments, the present invention innovatively proposes to simultaneously fabricate vertical vias and inclined vias on a glass interposer: 1. Without replacing equipment, inclined and vertical vias can be fabricated using a wedge-shaped transparent medium, significantly reducing processing costs. 2. The design of the inclined vias has a passive limiting effect, supports passive alignment coupling, and also perfectly fits the inclined angle coupling principle of the grating coupler, eliminating the need for an additional fiber array cover plate fixture, reducing packaging costs, shrinking the packaging size, and enhancing packaging compactness. 3. Since the fiber optic coupling packaging is arranged in the last process, high-temperature flip-chip reflow soldering will not affect the coupling stability between the optical fiber and the optical chip, ensuring high compatibility of the optoelectronic co-packaging process. The present invention will effectively reduce the size of the fiber array, simplify the packaging structure, improve the compactness and process flexibility of optoelectronic co-packaging, and is applicable to application fields with high bandwidth and low latency requirements such as data centers, AI computing, and high-performance computing.

Claims

1. A glass interposer optoelectronic co - interconnection packaging architecture, comprising a glass interposer, an optical chip, a packaging substrate, an electrical chip, and an optical fiber, characterized in that: The glass interposer is provided with inclined vias, vertical vias, and vertical via conductive posts; Among them, after the vertical vias are filled with conductive materials, vertical via conductive posts are formed, which are used as electrical connection channels between the upper and lower layers of the glass interposer; The inclined vias are arranged in the grating coupling region, and the aperture of the inclined vias is adapted to the diameter of the optical fiber. After the glass interposer, the optical chip, the packaging substrate, and the electrical chip are fixed, the optical fiber passes through the inclined vias and is aligned and contacted with the grating on the surface of the optical chip to achieve optical coupling between the optical fiber and the optical chip.

2. The glass interposer optoelectronic co - interconnection packaging architecture according to claim 1, wherein: The number of the inclined vias is n, n≥2; and adjacent inclined vias do not intersect each other.

3. The glass interposer optoelectronic co-integration packaging architecture according to claim 1, wherein: The inclined vias are generated by using a vertical laser source and the refraction effect of a wedge - shaped transparent medium. After refraction, the laser beam is incident on the glass interposer at an inclined angle, and the laser - induced etching technology is used; wherein, the wedge - shaped transparent medium is not damaged by the laser beam.

4. The glass adapter optoelectronic co-interconnection packaging architecture according to claim 1, wherein: The size of the glass interposer is panel - level or wafer - level, and the size of the wedge - shaped transparent medium is panel - level or wafer - level.

5. The glass interposer optoelectronic co - interconnection packaging architecture according to claim 2, wherein: The wedge - shaped transparent medium is provided with an integral periodic wedge - shaped unit on its surface to achieve large - scale precise preparation when n≥2.

6. The glass interposer optoelectronic co - interconnection packaging architecture according to claim 3, characterized in that: The refraction effect of the wedge - shaped transparent medium satisfies the following relationship: sin(α) = N*sin(β), N*sin(α - β) = sin(θ) Wherein, N is the refractive index of the wedge - shaped transparent medium, α is the angle between the inclined surface of the wedge - shaped transparent medium and the horizontal direction, the laser beam light source is perpendicular to the surface of the glass interposer, β is the refraction angle of the laser beam after entering the wedge - shaped transparent medium, and θ is the angle between the inclined via and the vertical direction.

7. The glass interposer optoelectronic co - interconnection packaging architecture according to claim 1, characterized in that: The optical chip is embedded in the packaging substrate, the surface electrode pads of the packaging substrate and the surface of the optical chip are on the same side, and the surface pads are at the same horizontal height; the glass interposer is packaged on the packaging substrate through a solder ball array and filled with underfill; the electrical chip is packaged on the upper surface of the glass interposer through a flip - chip bonding process; The glass interposer is provided with a plurality of vertical via conductive posts and inclined vias; the aperture of the inclined vias is larger than the diameter of the optical fiber, and the optical fiber is inserted into the inclined vias and contacts the surface of the optical chip to be aligned with the grating coupler.

8. The optoelectronic co-interconnection packaging architecture of the glass adapter board according to claim 1, wherein: The gap between the optical fiber and the grating coupler is filled with a refractive index matching liquid to improve the optical coupling efficiency and fix the optical fiber at the same time.

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