Optical transmission module and its manufacturing method

Abstract

An optical transmission module includes a first substrate, a second substrate, a plurality of light-emitting elements, and a plurality of optical fibers. The first substrate has a plurality of blind vias and a plurality of protrusions located between the blind vias, with the blind vias penetrating a first surface of the first substrate. The second substrate overlaps the first substrate and faces a second surface of the first substrate, the second surface of the first substrate being opposite to the first surface. The plurality of light-emitting elements are disposed on the second substrate and located between the second substrate and the first substrate, wherein the plurality of light-emitting elements respectively overlap the plurality of protrusions of the first substrate. The plurality of optical fibers are respectively connected to the plurality of protrusions of the first substrate.

Description

Technical Field

[0001] This invention relates to an optical module and a method for manufacturing the same, and more particularly to an optical transmission module and a method for manufacturing the same. Background Technology

[0002] Co-Packaged Optics (CPO) is an emerging technology that co-packages photonic integrated circuit (PIC) components and electrical integrated circuit (EIC) components onto the same carrier board. This shortens the signal transmission path, thereby reducing power consumption, signal loss, and improving transmission speed and performance. It is expected to be applied to industries that require high-performance transmission, such as artificial intelligence (AI), machine learning (ML), high-resolution video streaming, virtual reality (VR), drones, and automotive applications.

[0003] However, when using miniature light-emitting diodes (μLEDs) as the light source for fiber optic communication, the μLED light is scattered in the glass, making it difficult to improve the light transmission efficiency. Summary of the Invention

[0004] This invention provides an optical transmission module with improved optical transmission efficiency.

[0005] This invention provides a method for manufacturing an optical transmission module, which can improve the optical transmission efficiency of the optical transmission module.

[0006] One embodiment of the present invention provides an optical transmission module, including a first substrate, a second substrate, a plurality of light-emitting elements, and a plurality of optical fibers. The first substrate has a plurality of blind vias and a plurality of protrusions located between the blind vias, with the blind vias penetrating a first surface of the first substrate. The second substrate overlaps the first substrate and faces a second surface of the first substrate, the second surface of the first substrate being opposite to the first surface of the first substrate. The plurality of light-emitting elements are disposed on the second substrate and located between the second substrate and the first substrate, wherein the plurality of light-emitting elements respectively overlap the plurality of protrusions of the first substrate. The plurality of optical fibers are respectively connected to the plurality of protrusions of the first substrate.

[0007] An embodiment of the present invention provides a method for manufacturing an optical transmission module, comprising: forming a plurality of blind holes and a plurality of protrusions located between the plurality of blind holes on a first surface of a first substrate; forming a plurality of light-emitting elements on a second substrate; attaching a second surface of the first substrate to the second substrate such that the plurality of light-emitting elements are located between the second substrate and the first substrate, and the plurality of light-emitting elements respectively overlap the plurality of protrusions of the first substrate, wherein the second surface of the first substrate is opposite to the first surface of the first substrate; and bonding a plurality of optical fibers to the plurality of protrusions of the first substrate respectively.

[0008] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings for detailed explanation. Attached Figure Description

[0009] Figure 1 This is a schematic cross-sectional view of an optical transmission module 10 according to an embodiment of the present invention.

[0010] Figures 2A to 2E This is a cross-sectional schematic diagram of the manufacturing process of an optical transmission module 10 according to an embodiment of the present invention.

[0011] Figure 3 This is a schematic cross-sectional view of an optical transmission module 20 according to an embodiment of the present invention.

[0012] List of reference numerals

[0013] 10, 20: Optical transmission modules

[0014] 110, 120, 210: substrate

[0015] 112, 212: Blind holes

[0016] 112B: Bottom surface

[0017] 112S, 212S: Inner surface

[0018] 113, 213: Reflective layer

[0019] 114, 214: Protrusions

[0020] 114T: Top surface

[0021] 116: Spacer

[0022] 118, 218: Light collecting element

[0023] 122, 142, 146: Through holes

[0024] 124, 126, 148: Connecting pads

[0025] 128: Connector

[0026] 130: Light-emitting element

[0027] 132: Encapsulation layer

[0028] 134: Frame adhesive

[0029] 140: Rewiring Layer

[0030] 141: Insulation layer

[0031] 144: Conductive layer

[0032] 150: Fiber optic cable

[0033] 211: Groove

[0034] 211B: Bottom surface

[0035] H1~H4: Spacing

[0036] S11, S12, S21, S22: Surface

[0037] W1, W2: Dimensions Detailed Implementation

[0038] In the accompanying drawings, the thicknesses of layers, films, panels, regions, etc., are enlarged for clarity. Throughout the specification, the same reference numerals denote the same elements. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected" to another element, it may be directly on or connected to the other element, or intermediate elements may also be present. Conversely, when an element is referred to as being "directly on" or "directly connected" to another element, no intermediate elements are present. As used herein, "connection" can refer to a physical and / or electrical connection. Furthermore, "electrical connection" or "coupling" may mean that other elements exist between the two elements.

[0039] It should be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or part from another. Therefore, the first “element,” “component,” “region,” “layer,” or “part” discussed below may be referred to as a second element, component, region, layer, or part without departing from the teachings of this document.

[0040] The terminology used herein is for the purpose of describing particular embodiments only and is not restrictive. As used herein, unless the content clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one” or denoteing “and / or.” As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It should also be understood that, when used in this specification, the terms “comprising” and / or “including” specify the presence of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or combinations thereof.

[0041] Furthermore, relative terms such as “down” or “bottom” and “up” or “top” may be used herein to describe the relationship between one element and another, as illustrated in the figures. It should be understood that relative terms are intended to include different orientations of the device beyond those shown in the figures. For example, if a device in one figure is flipped, an element described as being “down” to other elements will be oriented “up” to other elements. Thus, the exemplary term “down” can include both “down” and “up” orientations, depending on the specific orientation of the figure. Similarly, if a device in one figure is flipped, an element described as being “down” or “below” to other elements will be oriented “above” to other elements. Thus, the exemplary terms “down” or “below” can include both “up” and “down” orientations.

[0042] Given the specific number of measurements discussed and the associated errors (i.e., limitations of the measurement system), the terms "about," "approximately," "generally," or "substantially" as used herein include the value and the average value within an acceptable range of deviations from the specific value as determined by one of ordinary skill in the art. For example, "about" may mean within one or more standard deviations of the value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, the terms "about," "approximately," "generally," or "substantially" as used herein may be chosen to select a more acceptable range of deviations or standard deviations depending on the optical, etched, or other properties, and a single standard deviation may not be applicable to all properties.

[0043] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having the same meaning as they have in the context of the relevant technology and the invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined herein.

[0044] This document describes exemplary embodiments with reference to cross-sectional views, which are schematic diagrams of idealized embodiments. Therefore, variations in shape as a result of, for example, manufacturing techniques and / or tolerances, are expected in the illustrations. Consequently, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but rather include, for example, shape deviations caused by manufacturing processes. For example, regions shown or described as flat may generally have rough and / or non-linear characteristics. Furthermore, the acute angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the precise shapes of the regions, nor are they intended to limit the scope of the claims.

[0045] Figure 1 This is a schematic cross-sectional view of an optical transmission module 10 according to an embodiment of the present invention. Please refer to... Figure 1 The optical transmission module 10 includes a substrate 110, a substrate 120, a plurality of light-emitting elements 130, and a plurality of optical fibers 150. The substrate 110 has a plurality of blind holes 112 and a plurality of protrusions 114 located between the blind holes. The plurality of light-emitting elements 130 are disposed on the substrate 120 and located between the substrate 110 and the substrate 120, wherein the plurality of light-emitting elements 130 respectively overlap the plurality of protrusions 114 of the substrate 110. The plurality of optical fibers 150 are respectively connected to the plurality of protrusions 114 of the substrate 110.

[0046] In one embodiment of the light transmission module 10 of the present invention, the light path of the light source of the light-emitting element 130 is adjusted by means of the protrusion 114 of the substrate 110, thereby improving the light transmission efficiency of the light transmission module 10. Hereinafter, in conjunction with... Figure 1 The implementation of the various components of the optical transmission module 10 will be described further, but the present invention is not limited thereto.

[0047] The substrate 110 of the optical transmission module 10 has a plurality of alternately arranged blind vias 112 and a plurality of protrusions 114. The blind vias 112 may penetrate the surface S11 of the substrate 110, and the blind vias 112 may not penetrate the surface S12 of the substrate 110, wherein the surface S12 may be opposite to S11. In some embodiments, the distance H1 from the bottom surface 112B of the blind via 112 to the surface S12 of the substrate 110 is about 1% to 50%, for example, about 10% to 20%, of the distance H2 between the surfaces S11 and S12 of the substrate 110. In some embodiments, the top surface 114T of the plurality of protrusions 114 is flush with the surface S11 of the substrate 110, but is not limited thereto. In other embodiments, the top surface 114T of the plurality of protrusions 114 is not flush with the surface S11 of the substrate 110.

[0048] The dimensions of the plurality of blind holes 112 are not particularly limited, and the dimensions of the plurality of blind holes 112 may be the same as or different from each other. Similarly, the dimensions of the plurality of protrusions 114 are not particularly limited, and the dimensions of the plurality of protrusions 114 may also be the same as or different from each other. In some embodiments, the dimensions of the plurality of blind holes 112 are the same, and the plurality of protrusions 114 may have various dimensions. For example, the dimensions of the protrusions 114 of the overlapping light-emitting element 130 are different from the dimensions of the protrusions 114 of the non-overlapping light-emitting element 130. Furthermore, the dimension W1 of the top surface 114T of the protrusions 114 of the overlapping light-emitting element 130 may be equal to or greater than approximately 30% of the dimension W2 of the light-emitting element 130. In some embodiments, the dimension W1 is approximately 30% to 150% of the dimension W2, for example, approximately 50% to 120%.

[0049] The substrate 120 of the optical transmission module 10 can overlap the substrate 110. The substrate 120 can have opposing surfaces S21 and S22, and the surface S21 of the substrate 120 can face the surface S12 of the substrate 110. In some embodiments, the substrate 120 includes a plurality of vias 122 and a plurality of pads 124 and 126, wherein the vias 122 penetrate the substrate 120, the pads 124 are located on the surface S21 of the substrate 120, the pads 126 are located on the surface S22 of the substrate 120, and the vias 122 electrically connect the pads 124 and 126.

[0050] The light-emitting element 130 can be disposed on the surface S21 of the substrate 120 and electrically connected to the pad 124 of the substrate 120. In this way, the light-emitting element 130 can be controlled by the signal transmitted by the substrate 120, for example, controlling the light-emitting time of the light-emitting element 130. In addition, the light-emitting surface of the light-emitting element 130 faces the protrusion 114 so that the light from the light-emitting element 130 enters the protrusion 114 of the substrate 110. In some embodiments, the refractive index of the protrusion 114 (e.g., about 1.5) is greater than the refractive index of the air in the blind hole 112 (e.g., about 1.0), so that the light incident on the sidewall of the protrusion 114 can be reflected without being refracted away from the protrusion 114, thereby improving the light utilization rate of the light-emitting element 130 and thus improving the light transmission efficiency.

[0051] In some embodiments, the optical transmission module 10 further includes a reflective layer 113, which can cover the inner surface 112S of a plurality of blind holes 112 to ensure that light incident on the sidewall of the protrusion 114 is reflected in the direction of the optical fiber 150, thereby helping to improve the light utilization of the light-emitting element 130 and thus improve the light transmission efficiency.

[0052] The light-emitting element 130 may be a miniature light-emitting diode. In some embodiments, the light-emitting element 130 is a resonant cavity light-emitting diode (RCLED) to provide collimated light. For example, the luminance ratio at a 45° viewing angle direction to the normal viewing angle direction of the RCLED may be about 0.1% to 5%. In some embodiments, the light-emitting element 130 may also be a vertical-cavity surface-emitting laser (VCSEL).

[0053] In some embodiments, the substrate 120 further includes a plurality of connectors 128, which are respectively disposed on a plurality of pads 126. The plurality of connectors 128 can be electrically connected to a plurality of vias 122 of the substrate 120 through the plurality of pads 126. The plurality of connectors 128 can electrically connect the optical transmission module 10 to an external device, such as other integrated circuit devices, enabling the optical transmission module 10 to receive, for example, control signals from the external device. The connectors 128 may include solder (e.g., solder balls) or other suitable materials.

[0054] In some embodiments, the optical transmission module 10 further includes a redistribution layer 140, which is disposed between the substrate 120 and the light-emitting element 130, and can electrically connect the light-emitting element 130 and the substrate 120. For example, the redistribution layer 140 includes an insulating layer 141, a plurality of vias 142 and 146, a conductive layer 144, and a plurality of pads 148, wherein the vias 142 can be electrically connected to the pads 124 of the substrate 120, the conductive layer 144 can be electrically connected to the vias 142 and 146, and the pads 148 can be electrically connected to the vias 146. The light-emitting element 130 can be electrically connected to the pads 148, and the light-emitting element 130 can be electrically connected to the vias 122, pads 124, 126, and connectors 128 of the substrate 120 through the redistribution layer 140.

[0055] In some embodiments, the optical transmission module 10 further includes an encapsulation layer 132, which may be located on the redistribution layer 140 and between the plurality of light-emitting elements 130, and the encapsulation layer 132 exposes at least the light-emitting surface of the light-emitting elements 130. The optical transmission module 10 may also include a plurality of spacers 116, wherein the plurality of spacers 116 may be located between the encapsulation layer 132 and the substrate 110, so as to maintain a substantially uniform spacing between the substrate 110 and the encapsulation layer 132, thereby maintaining a substantially uniform spacing between the substrate 110 and the substrate 120.

[0056] In some embodiments, the optical transmission module 10 further includes a sealant 134, which may be located between the encapsulation layer 132 and the substrate 110, and may be located at the edge region of the substrate 110 and / or the edge region of the encapsulation layer 132. The sealant 134 may surround the entire spacer 116 and the light-emitting element 130 to seal the spacer 116 and the light-emitting element 130 between the substrate 110 and the encapsulation layer 132.

[0057] The light transmission module 10 may further include a light-collecting element 118, which may be located between the protrusion 114 and the light-emitting element 130 in the normal direction of the substrates 110 and 120, so as to focus the emitted light of the light-emitting element 130 onto the protrusion 114 of the substrate 110. In some embodiments, the light-collecting element 118 is a microlens. For example, the light-collecting element 118 is a light-collecting lens, and the convex surface of the light-collecting element 118 faces the light-emitting element 130. In some embodiments, when the light-emitting element 130 is an RCLED, the light-collecting element 118 may not be provided.

[0058] The optical fiber 150 of the optical transmission module 10 can be coupled to the protrusion 114 of the substrate 110 to transmit light focused to the protrusion 114 to other components. Multiple optical fibers 150 may be, for example, a fiber array unit (FAU). In some embodiments, the optical fiber 150 is multimode fiber (MMF), but is not limited thereto. In other embodiments, the optical fiber 150 may be single-mode fiber (SMF).

[0059] Figures 2A to 2E This is a cross-sectional schematic diagram showing the steps of a method for manufacturing an optical transmission module 10 according to an embodiment of the present invention. First, please refer to... Figure 2A A substrate 110 is provided, which may be a transparent substrate and may be made of materials such as glass, quartz, polymer or other suitable materials. Then, a plurality of blind holes 112 and a plurality of protrusions 114 located between the plurality of blind holes 112 can be formed on the surface S11 of the substrate 110 using a photolithography process and an etching process.

[0060] In some embodiments, a laser is irradiated at the predetermined locations on the substrate 110 where blind vias 112 are to be formed, thereby modifying the portion of the substrate 110 to be removed. Subsequently, an etching process is used to remove the modified portion of the substrate 110, forming a plurality of blind vias 112. A plurality of protrusions 114 can be simultaneously formed between the plurality of blind vias 112. The top surface 114T of the plurality of protrusions 114 can be flush with the surface S11 of the substrate 110. The etching rate of the modified portion of the substrate 110 can be greater than the etching rate of the unmodified portion of the substrate 110. Furthermore, the laser energy and etching time used can be adjusted according to the required depth of the blind vias 112.

[0061] In some embodiments, a reflective layer 113 is also formed on the inner surface 112S and bottom surface 112B of a plurality of blind vias 112 of the substrate 110. The material of the reflective layer 113 may include a material with high reflectivity, such as a metal. For example, the reflective layer 113 may include at least one of aluminum (Al), silicon (Si), silver (Ag), gold (Au), and titanium dioxide (TiO2). In addition, the reflective layer 113 may have a single-layer or multi-layer structure, such as a stacked layer of the above materials or a stacked layer of the above materials and other materials. In some embodiments, the reflective layer 113 may have a floating potential.

[0062] Next, please refer to Figure 2B Spacers 116 can be formed on the surface S12 of the substrate 110 using methods such as nanoimprint lithography (NIL). Spacers 116 may include, but are not limited to, photosensitive spacer materials. In some embodiments, light-collecting elements 118 can also be formed on the surface S12 of the substrate 110 using nanoimprint lithography. In some embodiments, the light-collecting element 118 overlaps the protrusion 114 of the substrate 110.

[0063] Next, please refer to Figure 2C A plurality of light-emitting elements 130 are formed on a substrate 120. The substrate 120 may be a silicon interposer, a glass interposer, or an organic interposer. For example, a plurality of vias 122 may be formed in the substrate 120, and a plurality of pads 124 and 126 may be formed on the surface of the substrate 120. In some embodiments, the vias 122 may penetrate the substrate 120, and the pads 124 and 126 may be formed on the surface S21 of the substrate 120. The pads 124 and 126 may be electrically connected to the two ends of the vias 122.

[0064] In some embodiments, a redistribution layer 140 is first formed on the surface S21 of the substrate 120, and then a plurality of light-emitting elements 130 are transferred onto the redistribution layer 140 using a mass transfer process. The insulating layer 141, vias 142, conductive layer 144, vias 146, and a plurality of pads 148 of the redistribution layer 140 can be formed using thin film deposition, lithography, and etching processes. An encapsulation layer 132 can also be formed on the redistribution layer 140 and between the plurality of light-emitting elements 130. In some embodiments, the encapsulation layer 132 may include a black light-absorbing material to prevent reflected light or glare.

[0065] Next, please refer to Figure 2D The surface S12 of substrate 110 is attached to the surface S21 of substrate 120, such that the light-emitting element 130, the spacer 116, and the light-collecting element 118 are located between substrate 120 and substrate 110. The redistribution layer 140 is located between the plurality of light-emitting elements 130 and substrate 120, and the plurality of light-emitting elements 130 overlap the plurality of protrusions 114 of substrate 110 respectively. The plurality of light-emitting elements 130 may also overlap the plurality of light-collecting elements 118 respectively, such that the light-collecting elements 118 are located between the light-emitting elements 130 and the protrusions 114 of substrate 110. In this way, the light-collecting elements 118 can concentrate the light from the light-emitting elements 130 onto the protrusions 114.

[0066] For example, one of the substrates 110 and 120 can be brought closer to the other of the substrates 110 and 120, thereby bonding the encapsulation layer 132 on the substrates 110 and 120 together through the frame adhesive 134, so as to seal the spacer 116, the light collecting element 118 and the light emitting element 130 between the encapsulation layer 132 on the substrates 110 and 120, thus completing the bonding between the substrates 110 and 120.

[0067] Next, please refer to Figure 2E Multiple connectors 128 can be formed on multiple pads 126 on the surface S22 of the substrate 120, such that the multiple connectors 128 are electrically connected to the multiple pads 126 respectively. In some embodiments, the connectors 128 are formed on the pads 126 using controlled collapse chip connection (C4) technology. Then, multiple optical fibers 150 are respectively bonded to multiple protrusions 114 on the substrate 110 to complete the process. Figure 1 Fabrication of the optical transmission module 10 shown.

[0068] The following uses Figure 3 Further embodiments of the present invention will be described, and the following will be used... Figure 1The component designations and related content of the embodiments are described below, wherein the same or similar designations are used to represent the same or similar components, and descriptions of identical technical content are omitted. For explanations of the omitted parts, please refer to... Figure 1 The embodiments described below will not be repeated.

[0069] Figure 3 This is a schematic cross-sectional view of an optical transmission module 20 according to an embodiment of the present invention. The optical transmission module 20 may include a substrate 210, a spacer 116, a substrate 120, a plurality of light-emitting elements 130, an encapsulation layer 132, a frame adhesive 134, a redistribution layer 140, and a plurality of optical fibers 150. Figure 1 Compared to the substrate 110 of the optical transmission module 10 shown, Figure 3 The main difference of the substrate 210 of the optical transmission module 20 shown is that the substrate 210 has a groove 211 recessed from the surface S11 of the substrate 210, and the substrate 210 also has a plurality of blind holes 212 and a plurality of protrusions 214 located between the bottom surface 211B of the groove 211 and the surface S12 of the substrate 210. A plurality of optical fibers 150 can be coupled to the plurality of protrusions 214 of the substrate 210. In this way, the groove 211 can help fix the plurality of optical fibers 150.

[0070] Multiple blind holes 212 can penetrate the bottom surface 211B of the groove 211, and the multiple blind holes 212 do not penetrate the surface S12 of the substrate 210. In some embodiments, the distance H3 between the top surface 214T of the protrusion 214 and the surface S12 of the substrate 210 is less than the distance H4 between the surface S11 and the surface S12 of the substrate 210.

[0071] For example, a groove 211 can be formed on the surface S11 of the substrate 210 using a photolithography process and an etching process. Then, a plurality of blind holes 212 can be formed below the bottom surface 211B of the groove 211 using a laser modification process and an etching process. A plurality of protrusions 214 can be formed simultaneously between the plurality of blind holes 212.

[0072] The optical transmission module 20 may also use a light-collecting element 218 to replace the light-collecting element 118 of the optical transmission module 10, and the light-collecting element 218 may be a meta-lens, such as a nanoscale meta-lens. In some embodiments, when the light-emitting element 130 is an RCLED, the light-collecting element 218 may not be provided.

[0073] In some embodiments, the optical transmission module 20 further includes a reflective layer 213, which can cover the inner surface 212S of a plurality of blind holes 212 to reflect the light entering the protrusion 214 toward the optical fiber 150, thereby improving the optical transmission efficiency.

[0074] In summary, the optical transmission module of the present invention improves the light utilization rate of the light-emitting element and thus enhances the optical transmission efficiency of the optical transmission module by adjusting the optical path of the light-emitting element through the blind holes and protrusions on the substrate. Furthermore, the optical transmission module of the present invention ensures that the light from the light-emitting element is reflected towards the optical fiber by providing a reflective layer on the inner surface of the blind holes, thereby contributing to improved optical transmission efficiency. In addition, the optical transmission module of the present invention can also place the blind holes and protrusions of the substrate under a groove in the substrate to fix the optical fiber using the groove.

[0075] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An optical transmission module, comprising: A first substrate has a plurality of blind holes and a plurality of protrusions located between the plurality of blind holes, wherein the plurality of blind holes penetrate a first surface of the first substrate; A second substrate, overlapping the first substrate and facing the second surface of the first substrate, wherein the second surface of the first substrate is opposite to the first surface; Multiple light-emitting elements are disposed on the second substrate and located between the second substrate and the first substrate, wherein the multiple light-emitting elements respectively overlap the multiple protrusions of the first substrate; as well as Multiple optical fibers are respectively connected to the multiple protrusions of the first substrate.

2. The optical transmission module of claim 1, wherein the plurality of blind holes do not penetrate the second surface of the first substrate.

3. The optical transmission module as claimed in claim 1, wherein the distance between the top surface of the protrusion and the second surface of the first substrate is equal to or less than the distance between the first surface and the second surface of the first substrate.

4. The optical transmission module as described in claim 1, wherein the light-emitting element is a micro light-emitting diode, a resonant cavity light-emitting diode, or a vertical resonant cavity surface-emitting laser.

5. The optical transmission module as claimed in claim 1 further includes a reflective layer covering the inner surface of the plurality of blind holes.

6. The optical transmission module as claimed in claim 1 further includes a plurality of light-collecting elements disposed on the second surface of the first substrate and respectively located between the plurality of protrusions of the first substrate and the plurality of light-emitting elements.

7. The optical transmission module as described in claim 6, wherein the light-collecting element is a microlens or a superlens.

8. The optical transmission module of claim 7, wherein the convex surface of the microlens faces the light-emitting element.

9. The optical transmission module of claim 1 further includes a redistribution layer located between the second substrate and the plurality of light-emitting elements, and the redistribution layer electrically connects the plurality of light-emitting elements to the plurality of vias of the second substrate.

10. The optical transmission module of claim 9 further includes a plurality of spacers disposed between the first substrate and the redistribution layer, and located between the plurality of light-emitting elements.

11. A method for manufacturing an optical transmission module, comprising: A plurality of blind holes and a plurality of protrusions located between the plurality of blind holes are formed on the first surface of the first substrate; Multiple light-emitting elements are formed on the second substrate; The second surface of the first substrate is attached to the second substrate, such that the plurality of light-emitting elements are located between the second substrate and the first substrate, and the plurality of light-emitting elements overlap the plurality of protrusions of the first substrate, wherein the second surface of the first substrate is opposite to the first surface; as well as Multiple optical fibers are respectively bonded to the multiple protrusions of the first substrate.

12. The method for manufacturing an optical transmission module as claimed in claim 11, wherein the plurality of blind holes and the plurality of protrusions are formed using a laser modification process and an etching process.

13. The method of manufacturing an optical transmission module as claimed in claim 11, wherein forming the plurality of blind holes and the plurality of protrusions on the first surface of the first substrate further comprises: A groove is formed on the first surface of the first substrate; as well as The plurality of blind holes and the plurality of protrusions are formed below the bottom surface of the groove.

14. The method of manufacturing an optical transmission module as claimed in claim 11, wherein forming the plurality of light-emitting elements on the second substrate comprises: A redistribution layer is formed on the second substrate; as well as The plurality of light-emitting elements are placed on the redistribution layer.

15. The method of manufacturing an optical transmission module as claimed in claim 11, further comprising forming a reflective layer, wherein the reflective layer covers the inner surface of the plurality of blind holes.

16. The method of manufacturing an optical transmission module as claimed in claim 11, further comprising forming a spacer on the second surface of the first substrate before attaching the first substrate to the second substrate.

17. The method of manufacturing an optical transmission module as claimed in claim 16, further comprising forming a light-collecting element on the second surface of the first substrate before attaching the first substrate to the second substrate.

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