Photoelectric co-packaging structure based on glass substrate

Abstract

The invention provides a photoelectric co-packaging structure based on a glass substrate, and relates to the technical field of photon integration. The photoelectric co-packaging structure based on the glass substrate comprises a substrate, a core layer, an upper wrapping layer, a waveguide layer and a surface incidence detector which are stacked in sequence, wherein the waveguide layer comprises a grating structure, and the grating structure is used for vertically outputting an input optical signal; and the surface incidence detector is arranged on the grating structure and is used for receiving the vertically output optical signal and converting the received optical signal into an electric signal.

Description

Technical Field

[0001] The present disclosure relates to the technical field of photonic integration, and more particularly, to an optoelectronic co-packaging structure based on a glass substrate. Background Art

[0002] As the communication needs of data centers continue to grow, high-speed data transmission between chips has become a key bottleneck restricting the improvement of system performance. Traditional electrical interconnect solutions have been unable to meet the growing data rate requirements due to their inherent bandwidth limitations, signal integrity issues, and high power consumption. Especially in high-density integration environments, the physical limits of electrical interconnects have gradually emerged, making it difficult to further improve device performance and greatly limiting the degree of integration.

[0003] To solve these problems, researchers began to explore optical interconnect technology as a potential alternative. As the core component of optical interconnect, optical waveguide devices have the advantages of low loss, high bandwidth and anti-electromagnetic interference, which can significantly improve data transmission efficiency. In particular, embedding a thin glass layer (sub-millimeter range) in the device to make an integrated optical waveguide is considered to be one of the effective ways to overcome the bottleneck of electrical interconnection and achieve higher bandwidth and lower latency. However, how to achieve efficient coupling packaging between optical waveguide devices and integrated optoelectronic devices has become the focus and technical difficulty of current research. Summary of the invention

[0004] In view of this, the present disclosure provides an optoelectronic co-packaging structure based on a glass substrate.

[0005] The present disclosure provides an optoelectronic co-packaging structure based on a glass substrate, comprising: a substrate, a core layer, an upper cladding layer, a waveguide layer and a surface-incident detector stacked in sequence; wherein the waveguide layer comprises a grating structure, and the grating structure is used to vertically output an input optical signal; the surface-incident detector is arranged on the grating structure, and is used to receive the vertically output optical signal and convert the received optical signal into an electrical signal.

[0006] According to an embodiment of the present disclosure, the refractive index of the core layer is greater than the refractive index of the upper cladding layer; the refractive index of the core layer is greater than the refractive index of the substrate.

[0007] According to an embodiment of the present disclosure, the core layer includes: an optical waveguide structure for demultiplexing optical signals and coupling the demultiplexed optical signals into the waveguide layer between layers.

[0008] According to an embodiment of the present disclosure, it also includes: a through hole, which is arranged on the substrate and passes through an area on the core layer where no optical waveguide structure is provided, and an area on the upper cladding layer and the waveguide layer where no grating structure is provided.

[0009] According to an embodiment of the present disclosure, it also includes: an electrical redistribution layer, which is arranged on the through hole to achieve electrical connection.

[0010] According to an embodiment of the present disclosure, it also includes: a transimpedance amplifier, which is arranged on the surface-incident detector and contacts the electrical redistribution layer, and is used to amplify the electrical signal.

[0011] According to an embodiment of the present disclosure, it also includes: a printed circuit board, which is connected to the surface of the electrical redistribution layer close to the substrate and is used to drive the transimpedance amplifier and the surface incidence detector.

[0012] According to an embodiment of the present disclosure, the transimpedance amplifier is connected to the surface-incident detector and the electrical redistribution layer through solder balls; and the printed circuit board is connected to the electrical redistribution layer through solder balls.

[0013] According to an embodiment of the present disclosure, the thickness of the upper cladding layer is sub-micron level.

[0014] According to an embodiment of the present disclosure, the material of the core layer includes germanium-doped silicon dioxide; the material of the upper cladding layer includes phosphorus- and boron-doped silicon dioxide.

[0015] According to the embodiments of the present disclosure, a grating structure is provided in the waveguide layer to allow the optical signal to be emitted vertically, thereby achieving optical signal coupling output to a surface-incident detector, thereby improving the integration of the device.

[0016] According to the embodiments of the present disclosure, by providing a through hole on the substrate, electrical connection among the surface-incident detector, the transimpedance amplifier and the printed circuit board is achieved, the efficiency of electrical signal transmission is improved, and the integration of the overall device is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0018] Figure 1 Schematically shows a front view of the optoelectronic co-packaging structure of an embodiment of the present disclosure;

[0019] Figure 2 A schematic top view of an optoelectronic co-packaging structure according to an embodiment of the present disclosure is shown;

[0020] Figure 3 Schematically shows a flow chart of preparing a core optical waveguide structure according to an embodiment of the present disclosure;

[0021] Figure 4 Schematically shows a flow chart of preparing an optoelectronic co-packaging structure according to an embodiment of the present disclosure;

[0022] Description of reference numerals:

[0023] 1. Substrate; 2. Core layer; 3. Mask layer; 4. Photoresist; 5. Upper cladding layer; 6. Waveguide layer; 7. Grating structure; 8. Through hole; 9. Surface-incident detector; 10. Electrical redistribution layer; 11. Transimpedance amplifier; 12. Printed circuit board. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known systems and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] Figure 1 The main view of the optoelectronic co-packaging structure of the embodiment of the present disclosure is schematically shown.

[0029] Figure 2 The top view of the optoelectronic co-packaging structure according to the embodiment of the present disclosure is schematically shown.

[0030] like Figure 1 and Figure 2As shown, the present disclosure provides an optoelectronic co-packaging structure based on a glass substrate, comprising: a substrate 1, a core layer 2, an upper cladding layer 5, a waveguide layer 6 and a surface-incident detector 9 stacked in sequence; wherein the waveguide layer 6 comprises a grating structure 7, and the grating structure 7 is used to vertically output the input optical signal; the surface-incident detector 9 is arranged on the grating structure 7, and is used to receive the vertically output optical signal and convert the received optical signal into an electrical signal.

[0031] In the embodiments of the present disclosure, the photodetectors in the existing optoelectronic co-packaging structure are usually arranged on the side of the core layer to receive the optical signal output from the core layer. This arrangement of photodetectors makes the integration of the entire system low, which is not conducive to achieving a compact design. In addition, the use of wire bonding for electrical signal transmission not only increases the parasitic effect, but also limits the transmission speed and reliability.

[0032] Based on this, the embodiments of the present disclosure vertically couple and output the optical signal by setting a grating structure in the waveguide layer. At the same time, a surface-incident detector is set on the grating structure to receive the vertically output optical signal, thereby achieving efficient coupling of the optical signal and the surface-incident detector and improving the coupling efficiency and integration.

[0033] Based on the Bragg diffraction principle, the vertical coupling output of the optical signal can only be achieved when the incident optical signal satisfies the Bragg formula. The Bragg formula is as follows:

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] Where m is the diffraction order, F is the duty cycle of the grating, and are the effective refractive index of the region without grating structure on the waveguide layer and the effective refractive index of the region with grating structure on the waveguide layer, is the period of the grating, represents the propagation constant of the waveguide, represents the wave number of the incident light, Represents the raster vector size, represents the effective refractive index of the grating coupler, Represents the incident angle of the light source. Based on the principle that the grating structure will only diffract upward when it meets the Bragg diffraction condition, vertical coupling of the optical signal is achieved when the optical signal meets the Bragg formula.

[0040] At the same time, the optical signal output through the core layer can be coupled to the waveguide layer to achieve interlayer coupling, and based on the optical signal output to the waveguide layer, it is input into the grating structure to achieve efficient coupling output of the optical signal.

[0041] According to an embodiment of the present disclosure, the waveguide layer may be a silicon layer or a silicon nitride layer.

[0042] According to an embodiment of the present disclosure, the refractive index of the core layer is greater than the refractive index of the upper cladding layer; the refractive index of the core layer is greater than the refractive index of the substrate.

[0043] In the embodiments of the present disclosure, by controlling the refractive index difference between the core layer and the upper cladding layer and the substrate, the transmission loss can be effectively controlled. Meanwhile, the high refractive index difference can make the optical waveguide smaller and improve the integration.

[0044] In some possible embodiments, the refractive index differences between the core layer and the substrate and the upper cladding layer are all 0.36%, and the width and thickness of the optical waveguide structure may be 7 μm×7 μm.

[0045] In some possible embodiments, the refractive index differences between the core layer and the substrate and the upper cladding layer are all 0.3%, and the width and thickness of the optical waveguide structure may be 7 μm×7 μm.

[0046] In some possible embodiments, the refractive index differences between the core layer and the substrate and the upper cladding layer are all 0.45%, and the width and thickness of the optical waveguide structure may be 6.5 μm×6.5 μm.

[0047] In some possible embodiments, the refractive index differences between the core layer and the substrate and the upper cladding layer are all 0.75%, and the width and thickness of the optical waveguide structure may be 6 μm×6 μm.

[0048] In some possible embodiments, the refractive index differences between the core layer and the substrate and the upper cladding layer are all 1.5%, and the width and thickness of the optical waveguide structure may be 4.5 μm×4.5 μm.

[0049] In some possible embodiments, the refractive index differences between the core layer and the substrate and the upper cladding layer are all 2%, and the width and thickness of the optical waveguide structure may be 4 μm×4 μm.

[0050] In the embodiments of the present disclosure, the refractive index difference between the core layer and the substrate, the upper cladding layer and the size of the optical waveguide structure can be set as needed. It should be noted that the above gives a variety of possible examples, but is not limited to these.

[0051] According to an embodiment of the present disclosure, the core layer includes: an optical waveguide structure for demultiplexing optical signals and coupling the demultiplexed optical signals into the waveguide layer between layers.

[0052] According to an embodiment of the present disclosure, the optical waveguide structure may be a wavelength division multiplexing device.

[0053] In the embodiment of the present disclosure, an optical signal is input from a wavelength division multiplexing device, and after demultiplexing, is output from an output end through interlayer coupling to a waveguide layer.

[0054] According to an embodiment of the present disclosure, it also includes: a through hole 8, which is arranged on the substrate 1 and passes through the area on the core layer 2 where no optical waveguide structure is provided, and the area on the upper cladding layer 5 and the waveguide layer 6 where no grating structure 7 is provided.

[0055] According to an embodiment of the present disclosure, the through hole may be prepared by using one of a sandblasting method, a photosensitive glass method, a focused discharge method, a plasma etching method, a laser ablation method, and a laser induced etching method.

[0056] According to an embodiment of the present disclosure, it further includes: an electrical redistribution layer 10, which is disposed on the through hole 8 to achieve electrical connection.

[0057] In the embodiments of the present disclosure, a metal layer and a dielectric layer are deposited on the inner surface of a through hole to form an electrical redistribution layer (RDL) to carry a corresponding metal wiring pattern and rearrange the IO ports of the chip in a suitable area outside the chip. Since the line width and spacing of the metal wiring formed by the RDL are smaller, a higher interconnection density is provided. At the same time, the signal quality can be improved by shortening the circuit length, and the chip integration capability can be improved by reducing the chip area.

[0058] According to an embodiment of the present disclosure, it further includes: a transimpedance amplifier 11, which is arranged on the surface-incident detector 9 and contacts the electrical redistribution layer 10, and is used to amplify the electrical signal.

[0059] According to an embodiment of the present disclosure, it further includes: a printed circuit board 12 , which is connected to a surface of the electrical redistribution layer 10 close to the substrate and is used to drive the transimpedance amplifier 11 and the surface-incident detector 12 .

[0060] In an embodiment of the present disclosure, the transimpedance amplifier is connected to the surface-incident detector and the electrical redistribution layer through solder balls; and the printed circuit board is connected to the electrical redistribution layer through solder balls.

[0061] In an embodiment of the present disclosure, the surface incidence detector, the transimpedance amplifier and the printed circuit board are connected to the electrical redistribution layer through solder balls, and the power supply of the transimpedance amplifier and the surface incidence detector is achieved by supplying power to the circuit board, thereby shortening the electrical connection length. Compared with the traditional wire bonding connection method, this embodiment improves the transmission rate of electrical signals and the integration of the system.

[0062] According to an embodiment of the present disclosure, the thickness of the upper cladding layer is sub-micron level.

[0063] In the embodiments of the present disclosure, by controlling the thickness of the upper cladding layer, it is advantageous to achieve coupling output of the optical signal from the core layer to the waveguide layer.

[0064] According to an embodiment of the present disclosure, the material of the core layer includes germanium-doped silicon dioxide; the material of the upper cladding layer includes phosphorus- and boron-doped silicon dioxide.

[0065] In the embodiments of the present disclosure, the refractive index between the core layer and the substrate is regulated by controlling the content of germanium by doping the core layer with germanium. When the refractive index of the core layer is greater than the refractive index of the substrate and the refractive index of the upper cladding layer, the transmission loss of the optical signal can be reduced. According to the embodiments of the present disclosure, the material of the substrate can be undoped silicon dioxide, a single crystal thin sheet with a specific crystal plane and suitable electrical, optical and mechanical properties.

[0066] In the embodiments disclosed herein, by selecting a glass substrate with good electrical properties and low electrical loss, the signal separation can be improved. At the same time, the thermal expansion coefficient of glass is relatively small, which can well solve the problem of interposer warping caused by chip heating. At the same time, the Young's modulus of glass is relatively large, the hardness is greater, and the surface flatness is good, which can achieve fine line spacing and smaller packaging size. Therefore, using a glass substrate as an interposer in advanced packaging can achieve lower electrical transmission loss, higher transmission rate and higher integration. At the same time, an optical waveguide device structure is grown in the core layer of the glass substrate, and the interlayer coupling technology and etching grating structure are used to achieve vertical coupling of optical signals and surface-incident detectors. A glass through hole is etched on the glass substrate and an electrical redistribution layer is grown to achieve direct electrical connection between the upper and lower glass substrates, and finally achieve efficient electrical connection between the transimpedance amplifier, the surface-incident detector and the printed circuit board.

[0067] Figure 3 The flowchart of preparing the core optical waveguide structure according to the embodiment of the present disclosure is schematically shown.

[0068] like Figure 3 As shown, the embodiment of the present disclosure provides a method for preparing a core optical waveguide structure, comprising:

[0069] On the substrate, the Plasma Enhanced Chemical Vapor Deposition (PECVD) process is used to control the germanium content to deposit core layers with different refractive indices.

[0070] When etching the optical waveguide structure on the core layer, a hard mask layer 3 can be grown to ensure the photolithography quality and make the waveguide side wall vertical, and a photoresist 4 is spin-coated on the hard mask layer. The preset optical waveguide structure is etched by inductively coupled plasma (ICP) etching technology, and an upper cladding layer is grown on the optical waveguide structure by PECVD.

[0071] Figure 4 The flowchart of preparing the optoelectronic co-packaging structure according to the embodiment of the present disclosure is schematically shown.

[0072] like Figure 4 As shown, an embodiment of the present disclosure provides a method for preparing an optoelectronic co-packaging structure, comprising:

[0073] Step 1: Based on Figure 3 In the substrate containing the optical waveguide structure prepared in the embodiment, the upper cladding layer grown as above is polished and thinned to the sub-micron level, and a waveguide layer is grown.

[0074] Step 2: After etching the waveguide layer in the area corresponding to the grown optical waveguide structure, a layer of upper cladding layer is regrown based on the etched area.

[0075] Step 3: Etch a grating structure in the unetched area of ​​the waveguide layer, and passively integrate the surface-incident detector onto the grating structure.

[0076] Step 4: Etching a through-glass hole in the area of ​​the waveguide layer where the grating structure is not etched, and depositing a metal layer and a dielectric layer on the inner surface of the through-glass hole to form an electrical redistribution layer to carry the corresponding metal wiring pattern.

[0077] Step 5: Connect the transimpedance amplifier, surface-incidence detector and printed circuit board to the electrical redistribution layer through solder balls.

[0078] In the embodiments of the present disclosure, the preparation method is simple in process and can effectively shorten the length of the circuit and improve the quality of signal transmission by setting through holes. The connection between the transimpedance amplifier, detector and circuit board and the electrical redistribution layer is realized through solder balls, thereby realizing the electrical connection, power supply and grounding of the entire optical receiving component, thereby improving the system integration and signal transmission rate.

[0079] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0080] The embodiments of the present disclosure are described above. However, these embodiments are only for the purpose of illustration and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. An optoelectronic co-packaging structure based on a glass substrate, characterized in that: include: A substrate, a core layer, an upper cladding layer, a waveguide layer and a surface-incident detector are stacked in sequence; Wherein, the waveguide layer includes a grating structure, and the grating structure is used to output the input optical signal vertically; The surface-incident detector is arranged on the grating structure, and is used to receive the vertically output optical signal and convert the received optical signal into an electrical signal.

2. The optoelectronic co-packaging structure based on a glass substrate according to claim 1, characterized in that: The refractive index of the core layer is greater than the refractive index of the upper cladding layer; The refractive index of the core layer is greater than the refractive index of the substrate.

3. The optoelectronic co-packaging structure based on a glass substrate according to claim 2, characterized in that: The core layer comprises: The optical waveguide structure is used for demultiplexing optical signals and coupling the demultiplexed optical signals into the waveguide layer.

4. The optoelectronic co-packaging structure based on a glass substrate according to claim 3, characterized in that: Also includes: A through hole is provided on the substrate and passes through a region on the core layer where the optical waveguide structure is not provided, the upper cladding layer, and a region on the waveguide layer where the grating structure is not provided.

5. The optoelectronic co-packaging structure based on a glass substrate according to claim 4, characterized in that: Also includes: The electrical redistribution layer is disposed on the through hole and is used to realize electrical connection.

6. The optoelectronic co-packaging structure based on a glass substrate according to claim 5, characterized in that: Also includes: The transimpedance amplifier is arranged on the surface-incident detector and contacts the electrical redistribution layer, and is used for amplifying the electrical signal.

7. The optoelectronic co-packaging structure based on a glass substrate according to claim 6, characterized in that: Also includes: A printed circuit board is arranged to be connected to a surface of the electrical redistribution layer close to the substrate, and is used to drive the transimpedance amplifier and the surface incidence detector.

8. The optoelectronic co-packaging structure based on a glass substrate according to claim 7, characterized in that: The transimpedance amplifier is connected to the surface-incident detector and the electrical redistribution layer through solder balls; and the printed circuit board is connected to the electrical redistribution layer through solder balls.

9. The optoelectronic co-packaging structure based on a glass substrate according to claim 1, characterized in that: The thickness of the upper cladding layer is submicron level.

10. The optoelectronic co-packaging structure based on a glass substrate according to claim 1, characterized in that: The material of the core layer includes germanium-doped silicon dioxide; the material of the upper cladding layer includes phosphorus- and boron-doped silicon dioxide.

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