Array laser thermal isolation packaging structure, preparation method thereof and laser system

Abstract

The invention discloses an array laser thermal isolation packaging structure, a preparation method thereof and a laser system, belongs to the technical field of optical communication, and aims to improve the thermal isolation effect and long-term reliability of a laser chip. The packaging structure comprises an array laser and a heat dissipation structure. The array laser comprises a plurality of laser chips, a first groove is arranged between two adjacent laser chips, and the first groove at least separates active layers of the two adjacent laser chips. The heat dissipation structure comprises a heat conduction carrier, the heat conduction carrier comprises a first surface and a second surface which are opposite, the heat conduction carrier further comprises a plurality of second grooves, and the second grooves extend into the heat conduction carrier from the first surface. The array laser is arranged on the first surface, and one first groove and one second groove are correspondingly arranged and are communicated with each other.

Description

Technical Field

[0001] This application belongs to the field of optical communication technology, specifically an array laser thermal isolation packaging structure and its preparation method, and a laser system. Background Technology

[0002] Array lasers typically consist of multiple laser chips. However, current technologies cannot effectively block lateral heat conduction between these chips, leading to decreased temperature uniformity and reduced thermal isolation, which in turn affects their long-term reliability. Summary of the Invention

[0003] This application provides a thermally isolated packaging structure for an array laser, its fabrication method, and a laser system, aiming to improve the thermal isolation effect and long-term reliability of laser chips.

[0004] On one hand, a thermally isolated packaging structure for an array laser is provided. This packaging structure includes an array laser and a heat dissipation structure. The array laser includes multiple laser chips, with a first trench disposed between adjacent laser chips, the first trench separating at least the active layers of the adjacent laser chips. The heat dissipation structure includes a heat-conducting carrier, which includes opposing first and second surfaces. The heat-conducting carrier also includes multiple second trenches extending from the first surface into the heat-conducting carrier. The array laser is disposed on the first surface, with one first trench corresponding to and connected to one second trench.

[0005] The thermally isolated packaging structure for an array laser provided in the embodiments of this application includes an array laser and a heat dissipation structure. A first trench is provided between two adjacent laser chips, and the first trench separates at least the active layers of the two adjacent laser chips.

[0006] It is understandable that the active layer is the main heat-generating part of the array laser. By setting a first trench between two adjacent laser chips, the main heat-generating parts of the two adjacent laser chips can be separated, thereby separating the heat conduction path between the two adjacent laser chips through the first trench and allowing heat to enter the first trench, so as to achieve thermal isolation between the two adjacent laser chips.

[0007] Furthermore, the heat dissipation structure includes a heat conduction carrier, which comprises a first surface and a second surface facing each other. The heat conduction carrier also includes a plurality of second trenches extending from the first surface into the heat conduction carrier. The array laser is disposed on the first surface, with one first trench corresponding to and connected to one second trench.

[0008] Understandably, the heat dissipation structure is used to dissipate heat from the array laser. The second trenches on the first surface of the heat conduction carrier correspond one-to-one with and are connected to the first trenches. The first and second trenches can act as thermal barriers, thereby blocking heat conduction between two adjacent laser chips.

[0009] In this application, by setting the first trench of the array laser to be connected to the second trench of the heat dissipation structure, a full-link lateral thermal barrier covering the active layer, heat conduction carrier and heat sink is formed, which effectively extends the heat conduction path between adjacent laser chips, thereby improving the thermal isolation effect between adjacent laser chips, and thus improving the long-term reliability of the array laser thermal isolation packaging structure.

[0010] In some embodiments, a plurality of laser chips are arranged along a first direction, a first trench includes two opposite edges along the first direction, a second trench includes two opposite edges along the first direction, and the two edges of the first trench correspond one-to-one with and are connected to the two edges of the second trench.

[0011] In some embodiments, the first trench and the second trench communicate to form a cavity. In one example, the cavity is used to store high-purity air. Alternatively, in another example, the cavity is filled with a filler. Specifically, the filler material may include modified polyimide.

[0012] In some embodiments, the heat-conducting carrier further includes microchannels extending from the second surface into the heat-conducting carrier. The orthographic projection of the microchannels onto the first surface is offset from the orthographic projection of the second trench onto the first surface. Furthermore, in a planar direction parallel to the first surface, at least a portion of the microchannels and the second trench are directly opposite each other.

[0013] In some embodiments, the heat dissipation structure further includes a cover plate disposed on a second surface of the heat transfer carrier. The cover plate includes a through fluid inlet and a fluid outlet. The heat transfer carrier includes a plurality of spaced-apart microchannels, with the fluid inlet and fluid outlet each exposing at least a portion of the plurality of microchannels.

[0014] In some embodiments, the array laser further includes a first conductive layer and a second conductive layer disposed on opposite sides of the active layer, wherein the first conductive layer is closer to the heat dissipation structure than the second conductive layer. A first trench penetrates the first conductive layer along a third direction perpendicular to the first surface. The heat dissipation structure also includes a third conductive layer disposed on the first surface. A second trench penetrates the third conductive layer along a third direction. The third conductive layer includes a first portion and a second portion that are disconnected. The first conductive layer is electrically connected to the first portion, and the second conductive layer is electrically connected to the second portion.

[0015] In some embodiments, the array laser further includes a substrate disposed on the side of the active layer away from the heat dissipation structure. The substrate is made of indium phosphide, and the heat-conducting carrier is made of aluminum nitride ceramic.

[0016] On the other hand, this application also provides a method for fabricating a thermally isolated packaging structure for an array laser, the method comprising: An array laser is formed, which includes multiple laser chips. A first trench is provided between two adjacent laser chips, and the first trench separates the active layers of at least two adjacent laser chips. A heat dissipation structure is formed, which includes a heat conduction carrier, the heat conduction carrier includes a first surface and a second surface opposite to each other, and the heat conduction carrier also includes a plurality of second grooves, the second grooves extending from the first surface into the heat conduction carrier; An array laser is disposed on a first surface, with a first trench corresponding to and connected to a second trench.

[0017] The method for fabricating a thermally isolated packaging structure for an array laser provided in the embodiments of this application includes forming an array laser, the array laser including a plurality of laser chips, a first trench being provided between two adjacent laser chips, the first trench separating at least the active layers of the two adjacent laser chips.

[0018] It is understandable that the active layer is the main heat-generating part of the array laser. By setting a first trench between two adjacent laser chips, the main heat-generating parts of the two adjacent laser chips can be separated, thereby separating the heat conduction path between the two adjacent laser chips through the first trench and allowing heat to enter the first trench, so as to achieve thermal isolation between the two adjacent laser chips.

[0019] Furthermore, a heat dissipation structure is formed, which includes a heat conduction carrier. The heat conduction carrier includes a first surface and a second surface facing each other. The heat conduction carrier also includes a plurality of second grooves, which extend from the first surface into the heat conduction carrier. The array laser 1 is disposed on the first surface, with one first groove corresponding to and connected to one second groove.

[0020] Understandably, the heat dissipation structure is used to dissipate heat from the array laser. The second trenches on the first surface of the heat conduction carrier correspond one-to-one with and are connected to the first trenches. The first and second trenches can act as thermal barriers, thereby blocking heat conduction between two adjacent laser chips.

[0021] In this application, by setting the first trench of the array laser to be connected to the second trench of the heat dissipation structure, a full-link lateral thermal barrier covering the active layer, heat conduction carrier and heat sink is formed, which effectively extends the heat conduction path between adjacent laser chips, thereby improving the thermal isolation effect between adjacent laser chips, and thus improving the long-term reliability of the array laser thermal isolation packaging structure.

[0022] In some embodiments, placing the array laser on the first surface includes: setting alignment marks on the laser chip and the heat dissipation structure, respectively. The alignment marks are identified using an alignment system, and the array laser is placed on the first surface such that a first groove of the array laser corresponds to and communicates with a second groove of the heat dissipation structure.

[0023] In some embodiments, the array laser further includes a first conductive layer and a second conductive layer disposed on opposite sides of the active layer, wherein the first conductive layer is closer to the heat dissipation structure than the second conductive layer. A first trench penetrates the first conductive layer along a third direction perpendicular to the first surface. The heat dissipation structure also includes a third conductive layer disposed on the first surface. A second trench penetrates the third conductive layer along a third direction, and the third conductive layer includes a first portion and a second portion that are disconnected.

[0024] After the array laser is placed on the first surface, the above-mentioned fabrication method further includes: welding the first conductive layer to the first part and bonding the second conductive layer to the second part.

[0025] On the other hand, a laser system is also provided, comprising an array laser thermally isolated encapsulation structure and an optical transmission system as described in any of the above embodiments. The optical transmission system is coupled to the array laser thermally isolated encapsulation structure.

[0026] The laser system described above has the same structure and beneficial technical effects as the array laser thermal isolation packaging structure provided in some of the above embodiments, and will not be described again here.

[0027] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0028] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A schematic diagram of the thermally isolated packaging structure of an array laser provided in an embodiment of this application; Figure 2 for Figure 1 A magnified view of the array laser in the package structure, with the image inverted at point M; Figure 3 for Figure 2 A cross-sectional view of the array laser along section line AA'; Figure 4 for Figure 1 A magnified view of the heat dissipation structure in the packaging structure; Figure 5 for Figure 4 A cross-sectional view of part of the heat dissipation structure along section line BB'; Figure 6 for Figure 4 Top view of the heat dissipation structure in the middle; Figure 7 A flowchart illustrating the fabrication method of the thermally isolated packaging structure for an array laser provided in an embodiment of this application; Figure 8 This is a structural block diagram of a laser system provided for an embodiment of this application. Detailed Implementation

[0029] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0030] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0031] In the description of this application, "multiple" means two or more.

[0032] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] In describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be interpreted broadly; for example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. The term "electrical connection" indicates, for example, that two or more components have direct physical or electrical contact, but may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content of this document.

[0034] In addition, the use of “based on” implies openness and inclusivity, because processes, steps, calculations or other actions “based on” one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0035] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0036] This document describes exemplary embodiments with reference to cross-sectional views, which are intended as idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations caused, for example, by manufacturing processes. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0037] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0038] Thermally isolated array laser structures, with their high power, multiple wavelengths, and high integration, are widely applicable in fields such as optical communication, scientific research and defense, and medical and biological fields.

[0039] In the field of optical communication, thermally isolated array laser structures can serve as core light sources for high-bandwidth transmission. With the increasing prevalence of data centers, 5G or 6G communications, and fiber-to-the-home (FTTH), the requirements for bandwidth, speed, and power consumption in optical communication continue to rise. Distributed feedback lasers (DFBs) have become key components of highly integrated optical modules. In architectures such as co-packaged optics (CPO) and silicon photonics modules, multi-channel array lasers (e.g., 8-channel, 16-channel) can provide ultra-high bandwidth transmissions such as 800G / 1.6T / 3.2T. Combined with silicon-based photonic chips, they can achieve low-latency, low-power interconnection between switches and servers within data centers.

[0040] In scientific research and defense, thermal isolation structures for array lasers can be used in extreme conditions and specialized applications. Cutting-edge research such as high-energy physics experiments and astronomical observations place stringent demands on the stability, wavelength accuracy, and output power of light sources. Thanks to their excellent thermal management performance, thermal isolation structures for array lasers can operate stably in harsh environments such as extreme temperatures and high radiation, providing reliable light source support for scientific research equipment.

[0041] Specialized applications such as lidar, laser guidance, and optoelectronic countermeasures pose greater challenges to laser performance. The thermal isolation structure of array lasers, through optimized thermal design, effectively reduces the impact of thermal crosstalk on laser performance, improving output power and wavelength stability.

[0042] In the medical and biological fields, thermally isolated array laser structures can serve as high-precision diagnostic tools. Leveraging their unique advantages, thermally isolated array laser structures offer innovative solutions to these fields. In medical imaging, their stable light source output and high-precision wavelength control significantly improve the resolution and clarity of imaging equipment, helping doctors more accurately observe internal human structures, detect minute lesions, and provide strong evidence for early disease diagnosis.

[0043] In the field of biological detection, the application of this structure enables detection instruments to more sensitively capture weak signals from biomolecules, improving the accuracy and reliability of detection and providing more precise tools for biomedical research and clinical diagnosis. Meanwhile, in laser therapy, the thermal isolation structure of the array laser, through optimized thermal management, reduces the impact of thermal damage on surrounding tissues, improving the safety and effectiveness of treatment.

[0044] However, in array lasers, thermal crosstalk between multiple array laser chips is a core bottleneck for high-power, high-density applications. Due to the close proximity of the chips, the heat generated during operation is easily transferred between them, leading to localized temperature increases, which in turn affects key performance indicators such as laser output power, wavelength stability, and lifespan.

[0045] Traditional solutions typically employ microchannel heat sinks (MCHS) to cool chips. MCHS involves etching multiple micrometer-scale fluid channels onto a substrate. The relatively large heat exchange area between the fluid and the heat source within these channels allows for rapid heat transfer, significantly reducing temperature differences and heat transfer effects between chips and mitigating thermal crosstalk. In practice, the microchannel design utilizes silicon-based or ceramic materials, combined with precision photolithography, to optimize channel layout (such as serpentine or mesh structures) for uniform cooling and minimal pressure drop, making it suitable for high-density, high-power array laser applications.

[0046] However, firstly, in MCHS, lateral heat conduction between chips is not effectively blocked. Microchannel heat dissipation mainly removes vertical heat through forced convection of coolant, but it lacks physical isolation for lateral heat conduction between chips (such as through carrier materials or packaging interfaces). This lateral heat conduction still causes the temperature of edge chips to be 5°C to 8°C higher than that of the center chip, leading to wavelength drift and uneven output power.

[0047] Furthermore, the flow channel design of microchannels is usually based on the assumption of uniform heat distribution, while actual DFB lasers may have local hot spots due to differences in driving current or process deviations. A single microchannel cannot specifically guide the heat flux to bypass the hot spot area, leading to heat accumulation in the hot spot area and further increasing the hot spot temperature.

[0048] Secondly, in MCHS (Multi-Chip Hybrid System), the temperature uniformity among multiple chips decreases significantly. Uneven coolant flow distribution within the microchannels is a common problem. For example, the flow rate in the edge channels of a parallel microchannel may be 20%–30% lower than that in the center channel, leading to insufficient heat dissipation for the edge chips. In high-density DFB laser arrays, this flow imbalance can cause the temperature difference between chips to exceed 10°C, far exceeding the wavelength stability requirements of optical communication systems (<0.1 nm / °C). A single microchannel cannot effectively isolate the thermal effects of adjacent chips, leading to thermal cascading, where an increase in temperature in one chip can be conducted to adjacent chips through the carrier, creating a vicious cycle.

[0049] Furthermore, the aforementioned heat dissipation issues may lead to thermal stress risks and long-term reliability risks for the array laser. The mismatch in the coefficient of thermal expansion (CTE) of the materials amplifies thermal stress. The CTE of the microfluidic carrier (such as copper or silicon) differs significantly from that of the DFB chip. For example, the CTE of a silicon chip is 2.6 × 10⁻⁶. -6 / K, while the CTE of copper microchannels is 16.5×10 -6 At high temperatures, thermal stress can cause chip cracking or bonding interface failure. Furthermore, unisolated lateral heat conduction accelerates aging due to localized high temperatures, leading to prolonged high-temperature conditions in localized areas of the chip and accelerating the degradation of the active layer material. For example, the lifetime of a DFB laser on an indium phosphide (InP) substrate is 80% shorter at 85°C than at 25°C, and a single microchannel cannot effectively control hotspot temperatures, significantly reducing device reliability.

[0050] To address at least one of the aforementioned problems, in one aspect, embodiments of this application provide a thermally isolated packaging structure for an array laser. Figure 1 A schematic diagram of the thermally isolated packaging structure of an array laser provided in an embodiment of this application; Figure 2 for Figure 1 A magnified view of the array laser in the package structure, with the image inverted at point M; Figure 3 for Figure 2 A cross-sectional view of the array laser along section line AA'; Figure 4 for Figure 1 A magnified view of the heat dissipation structure in the packaging structure.

[0051] See Figure 1 The thermally isolated packaging structure 10 for the array laser includes an array laser 1 and a heat dissipation structure 2.

[0052] Among them, the array laser 1 is a laser system composed of multiple laser chips 3 arranged and combined in a certain pattern. It achieves high power and high brightness output through beam combining or phase control, and is widely used in industrial processing, communication, medical, military and other fields.

[0053] The array laser 1 includes multiple laser chips 3, which, for example, can be DFB chips. The multiple laser chips 3 can be arranged in the same direction, or in different directions, or partially in the same direction and partially in different directions. The embodiment of this application illustrates this with eight laser chips 3 arranged in direction X.

[0054] For example, heat dissipation structure 2 is the heat sink of package structure 10. Here, heat sink refers to a key component in electronic devices or high-power devices that is used to absorb and dissipate heat. It can efficiently transfer the heat generated by the device to the surrounding environment (such as air or coolant) by increasing the heat dissipation area and optimizing the heat conduction path, thereby maintaining the operating temperature of the device within a safe range.

[0055] In this application, the array laser 1 generates heat during operation, and the heat dissipation structure 2 acts as a heat sink to dissipate heat from the array laser 1. For example, the orthographic projection of the array laser 1 onto the heat dissipation structure 2 is located within the heat dissipation structure 2, meaning that the planar dimension of the heat dissipation structure 2 can be larger than the planar dimension of the array laser 1, thereby facilitating omnidirectional heat dissipation of multiple laser chips 3.

[0056] See Figure 2 and Figure 3 A first trench 17 is provided between two adjacent laser chips 3, and the first trench 17 separates the active layers 13 of the two adjacent laser chips 3 at least.

[0057] For example, the active layer 13 consists of a compressively strained indium gallium arsenide phosphide (InGaAsP) quantum well with a tensile strain barrier, and lower and upper InGaAsP separated confinement heterostructure (SCH) layers. By adjusting the composition of the InGaAsP quantum well, a specific photoluminescence wavelength can be achieved.

[0058] Among them, the active layer 13 is the main heat-generating part of the laser chip 3.

[0059] For example, see [link to previous article] Figure 2 and Figure 3 The array laser 1 also includes a substrate 11, and a waveguide layer 12, an active layer 13, a grating layer 14, an upper cladding layer 15, and a ridge waveguide 16 sequentially stacked on the substrate 11. For example, the substrate 11 can be an N-type indium phosphide substrate, and the upper cladding layer 15 can be a P-type upper cladding layer.

[0060] For example, the material of the substrate 11 can be any semiconductor material, such as gallium arsenide (GaAs), indium phosphide, or indium antimonide (InSb). The embodiments of this application are illustrated by taking indium phosphide as the material of the substrate 11.

[0061] For example, the ridge waveguide 16 is a dual-channel structure. The ridge waveguide 16 can confine the laser mode field within the waveguide by the refractive index difference with the air on both sides, thereby coupling higher-order spatial modes to the high-loss planar region to achieve single-mode operation. Along the Z direction, the depth of the ridge waveguide 16 can extend to the grating layer 14, and the width of the aforementioned dual-channel structure along the X direction can be tens of micrometers.

[0062] For example, see [link to example]. Figure 2 and Figure 3 Along direction Z, the depth of the first trench 17 at least penetrates the active layer 13, thereby separating the main heat-generating parts (active layer 13) of two adjacent laser chips 3 in direction Z. In the embodiments of this application, the first trench 17 penetrating both the active layer 13 and the waveguide layer 12 is used as an example. For example, along direction X, the width of the first trench 17 can range from 15μm to 25μm. Along direction Y, the length of the first trench 17 is the same as the length of the active layer 13, thereby separating two adjacent laser chips 3 in direction Y.

[0063] See Figure 4 The heat dissipation structure 2 includes a heat conduction carrier 21, which includes a first surface 211 and a second surface 212 opposite to each other. The heat conduction carrier 21 also includes a plurality of second grooves 25, which extend from the first surface 211 into the heat conduction carrier 21.

[0064] For example, along direction X, the width of the second groove 25 can range from 18μm to 28μm. It is understood that the width of the second groove 25 can be the same as or different from the width of the first groove 17. Since the process of forming the groove has process deviations, a certain process dimensional margin can be left in the process of forming the second groove 25 and the first groove 17.

[0065] For example, the material of the heat transfer carrier 21 can be a silicon-based material or a ceramic material. For instance, the silicon-based material can be silicon oxide, silicon carbide, or polycrystalline silicon. The ceramic material can be alumina ceramic, silicon nitride ceramic, or silicon carbide ceramic.

[0066] When the heat conduction carrier 21 is made of silicon, it exhibits high compatibility with semiconductor processes. High-precision microstructures can be achieved through micro / nano fabrication techniques such as photolithography and etching, significantly improving the heat dissipation area and heat exchange efficiency of the array laser 1. Some silicon-based materials have excellent thermal expansion coefficients that match the chip materials, effectively reducing interface failures caused by thermal stress and extending chip lifespan. Simultaneously, silicon-based materials have a low density (2.33 g / cm³), making them lightweight and suitable for weight-sensitive applications such as aerospace and portable electronics. Furthermore, the silicon-based heat conduction carrier 21 can be integrated into chip packaging to achieve optoelectronic co-packaging or three-dimensional stacked heat dissipation, meeting the compact requirements of high-power-density electronic devices.

[0067] When the material of the heat transfer carrier 21 is ceramic, the ceramic material exhibits excellent electrical insulation properties (volume resistivity > 10). 14With its core advantage of (Ω*cm), it can be directly applied to heat dissipation in high-voltage electronic devices without the need for an additional insulating layer. It exhibits outstanding high-temperature resistance (e.g., aluminum nitride ceramics have an operating temperature greater than 800°C, and silicon carbide ceramics have an operating temperature greater than 1600°C), strong chemical stability, and suitability for harsh environments. High thermal conductivity can be achieved through material optimization, bringing the thermal conductivity of the heat transfer carrier 21 close to that of metals. Furthermore, the ceramic heat transfer carrier 21 can have its impact resistance improved through toughening technology, and its design incorporates finned, columnar, and other structures to increase the heat dissipation area, balancing efficient heat dissipation with mechanical reliability.

[0068] See Figure 1 An array laser 1 is disposed on a first surface 211, and a first groove 17 corresponds to and is connected to a second groove 25.

[0069] It is understandable that, such as Figure 2 The array laser 1 shown is inverted as follows: Figure 4 The heat dissipation structure 2 shown is as follows: Figure 1 The array laser thermal isolation packaging structure 10 is shown. The first trench 17 and the second trench 25 are connected in a one-to-one correspondence, thereby forming a "chip-carrier" through trench array in the array laser thermal isolation packaging structure 10.

[0070] The above-mentioned through-type trench array design prevents the heat from the active layer 13 from spreading laterally when the laser chip 3 is working. Instead, the heat can only enter the heat conduction carrier 21 through the first trench 17 and the second trench 25. This changes the defect of localized thermal resistance concentration in traditional single-chip-level trenches. In the packaging structure 10 provided by the embodiments of this application, a full-link lateral thermal barrier covering the active layer 13, the heat conduction carrier 21, and the heat sink is formed, which extends the heat conduction path between adjacent laser chips 3 by more than three times, improves the lateral heat conduction path of the laser chip 3, and thus enhances the thermal isolation effect between adjacent laser chips 3.

[0071] The thermally isolated packaging structure 10 for an array laser provided in the embodiments of this application includes an array laser 1 and a heat dissipation structure 2. A first trench 17 is provided between two adjacent laser chips 3, and the first trench 17 separates at least the active layers 13 of the two adjacent laser chips 3.

[0072] It is understandable that the active layer 13 is the main heat-generating part of the array laser 1. By setting the first trench 17 between two adjacent laser chips 3, the main heat-generating parts of the two adjacent laser chips 3 can be separated, thereby separating the heat conduction path between the two adjacent laser chips 3 through the first trench 17 and allowing heat to enter the first trench 17, so as to achieve thermal isolation between the two adjacent laser chips 3.

[0073] Furthermore, the heat dissipation structure 2 includes a heat conduction carrier 21, which includes a first surface 211 and a second surface 212 facing each other. The heat conduction carrier 21 also includes a plurality of second grooves 25, which extend from the first surface 211 into the heat conduction carrier 21. The array laser 1 is disposed on the first surface 211, and one first groove 17 corresponds to and communicates with one second groove 25.

[0074] Understandably, the heat dissipation structure 2 is used to dissipate heat from the array laser 1. The second groove 25 provided on the first surface 211 of the heat conduction carrier 21 corresponds one-to-one with and is connected to the first groove 17. The first groove 17 and the second groove 25 can serve as a thermal barrier, thereby blocking heat conduction between two adjacent laser chips 3.

[0075] In this application, by setting the first trench 17 of the array laser 1 to be connected to the second trench 25 of the heat dissipation structure 2, a full-link lateral thermal barrier covering the active layer 13, the heat conduction carrier 21 and the heat sink is formed, which effectively extends the heat conduction path between adjacent laser chips 3, thereby improving the thermal isolation effect between adjacent laser chips 3, and thus improving the long-term reliability of the array laser thermal isolation packaging structure 10.

[0076] In some embodiments, see Figure 1 Multiple laser chips 3 are arranged along a first direction X. The first trench 17 includes two opposite edges E along the first direction X, and the second trench 25 includes two opposite edges F along the first direction X. The two edges E of the first trench 17 and the two edges F of the second trench 25 correspond one-to-one and are connected.

[0077] It is understood that, along the first direction X, the width of the first groove 17 of the array laser 1 is equal to and completely corresponds to the width of the second groove 25 of the heat dissipation structure 2, so that the lateral heat between adjacent laser chips 3 in the first groove 17 can be completely transferred into the second groove 25, thereby further improving the thermal isolation effect of the first groove 17 between adjacent laser chips 3, and further improving the heat dissipation effect of the heat dissipation structure 2.

[0078] For example, the width of the second trench 25 and the spacing between two adjacent second trenches 25 are perfectly matched with the first trench 17 to form a perfectly matched "chip-carrier" through trench array.

[0079] In some embodiments, see Figure 1The first trench 17 and the second trench 25 are connected to form a cavity 4. The cavity 4 is used to store high-purity air. It is understood that high-purity air has low thermal conductivity. By setting high-purity air in the cavity 4, efficient thermal isolation between adjacent laser chips 3 can be achieved, thereby further blocking heat conduction between adjacent laser chips 3. This is beneficial for reducing the temperature of the peripheral laser chips 3 and improving the temperature uniformity of multiple laser chips 3.

[0080] For example, in scenarios requiring extreme thermal isolation efficiency, such as forming a CPO light engine, high-purity air can be filled into cavity 4. This high-purity air has a thermal conductivity of only 0.025 W / (m*K), which is 1 / 6000th the thermal conductivity of silicon. By using a sealing process to prevent air convection from weakening the isolation effect, it can directly block more than 80% of lateral heat conduction. Here, "W / (m*K)" is a unit of thermal conductivity, representing the amount of heat transferred per second through one square meter of area when the temperature difference between the two sides is one Kelvin (1°C) in a one-meter-thick material (the unit of heat is watts W).

[0081] Alternatively, see [link to relevant document] Figure 1 The encapsulation structure 10 also includes a filler disposed in the cavity 4, the filler having the effects of heat resistance, insulation, and support. For example, the filler material can be modified polyimide, mica-based composite material, or aerogel composite material, etc.

[0082] Preferably, the filler material includes modified polyimide. It is understood that modified polyimide has high insulation resistance and good mechanical strength. By providing a filler of modified polyimide within the cavity 4, the support of the first trench 17 and the second trench 25 can be improved, thereby enhancing the mechanical strength of the encapsulation structure 10.

[0083] For example, in scenarios requiring both mechanical strength and insulation, such as forming an industrial-grade array laser 1, the cavity 4 can be filled with modified polyimide. This modified polyimide has a thermal conductivity of 0.25 W / m*K and an insulation resistance of 10 Ω·m. 14 The tensile strength is 150 MPa, measured in Ω*cm. Modified polyimide not only achieves thermal isolation between two adjacent laser chips 3, but also provides structural support for the laser chips 3, preventing edge embrittlement and cracking after etching, thereby improving the structural stability of the array laser 1.

[0084] In some embodiments, see Figures 1-3The array laser 1 also includes a first conductive layer 18 and a second conductive layer 19 disposed on opposite sides of the active layer 13. The first conductive layer 18 is closer to the heat dissipation structure 2 than the second conductive layer 19. A first trench 17 penetrates the first conductive layer 18 along a third direction Z perpendicular to the first surface 211.

[0085] For example, a first conductive layer 18 is disposed on the side of the substrate 11 away from the active layer 14, and a second conductive layer 19 is disposed on the side of the upper cladding layer 15 away from the substrate 11. The first conductive layer 18 can serve as the P-side conductive layer of the array laser 1, and the second conductive layer 19 can serve as the N-side conductive layer of the array laser 1. It is understood that the first conductive layer 18 and the second conductive layer 19 are the two electrodes of the array laser 1. The first trench 17 penetrates the first conductive layer 18, the upper cladding layer 15, the grating layer 14, the active layer 13, and the waveguide layer 12.

[0086] For example, the first conductive layer 18 can be a stack of three metals: titanium (Ti), platinum (Pt), and gold (Au). The thickness of the titanium layer can be 50 nm, the thickness of the platinum layer can be 100 nm, and the thickness of the gold layer can be 1000 nm.

[0087] For example, the second conductive layer 19 can be a stack of three metals: gold (Au), germanium (Ge), and nickel (Ni). The thickness of the gold layer can be 1000 nm, the thickness of the germanium layer can be 50 nm, and the thickness of the nickel layer can be 100 nm.

[0088] See Figure 4 The heat dissipation structure 2 also includes a third conductive layer 23 disposed on the first surface 211. A second trench 25 penetrates the third conductive layer 23 along the third direction Z. The third conductive layer 23 includes a first portion 231 and a second portion 232 that are disconnected.

[0089] For example, the material of the third conductive layer 23 can be a stack of three metals: copper, titanium, and gold.

[0090] For example, the heat dissipation structure 2 also includes pads 24 disposed on the first part 231. The material of the pads 24 may be an alloy containing 80% tin and 20% gold. Metal wiring is disposed on the second part 232.

[0091] The first conductive layer 18 is electrically connected to the first part 231, and the second conductive layer 19 is electrically connected to the second part 232.

[0092] For example, the first conductive layer 18 and the first part 231 can be electrically connected by soldering to the pads 24. The second conductive layer 19 and the second part 232 can be electrically connected by metal wiring bonding.

[0093] For example, along direction Z, the second trench 25 penetrates the pad 24 and the first part 231 and extends into the heat conduction carrier 21, and the depth of the second trench 25 can be in the range of 5μm to 8μm.

[0094] It is understood that one side electrode of the array laser 1 (first conductive layer 18) is electrically connected to the heat dissipation structure 2 through the first part 231 of the third conductive layer 23, and the other side electrode of the array laser 1 (second conductive layer 19) is led out through the second part 232 of the third conductive layer 23, which can be used for subsequent electrical connection between the array laser 1 and other devices.

[0095] In some embodiments, see Figures 1-4 The array laser 1 also includes a substrate 11, which is disposed on the side of the active layer 13 away from the heat dissipation structure 2. The substrate 11 is made of indium phosphide (InP), and the heat conduction carrier 21 is made of aluminum nitride (AlN) ceramic.

[0096] Understandably, the thermal stress generated at high temperatures may cause cracking of the laser chip 3 or failure of the bonding interface. The InP substrate 11 has a matching coefficient of thermal expansion with the AlN thermal conductive carrier 21, which can improve the problem of cracking of the laser chip 3 or failure of the bonding interface.

[0097] For example, the thermal conductivity of AlN ceramic materials is approximately 170 W / (m*K) to 200 W / (m*K), which is relatively high. The volume resistivity of AlN ceramic materials is approximately 10⁻⁶. 14 The insulation performance is good, with an Ω*cm. The thermal expansion coefficient of AlN ceramic material is 4.5ppm / ℃, which matches that of InP. Based on these characteristics, the heat transfer carrier 21 can achieve both trench matching (matching of the first trench 17 and the second trench 25) and electrical signal transmission.

[0098] Figure 5 for Figure 4 A cross-sectional view of part of the heat dissipation structure along section line BB'.

[0099] In some embodiments, see Figure 5 The heat transfer carrier 21 also includes microchannels 26 extending from the second surface 212 into the heat transfer carrier 21. The orthographic projection of the microchannel 26 onto the first surface 211 is offset from the orthographic projection of the second groove 25 onto the first surface 211. Furthermore, in the XY direction parallel to the first surface 211, at least a portion of the microchannel 26 is directly opposite the second groove 25.

[0100] For example, the microchannels 26 are distributed in the middle region of two adjacent thermal isolation trenches 27, using a parallel channel array. It can be understood that the depth of the microchannels 26 exceeds the bottom of the second trench 25 on the first surface 211, thereby maximizing the shortening of the heat conduction path from the active layer 13 of the laser chip 3 to the microchannels 26, while avoiding the overlap of the microchannels 26 and the second trench 25 in the Z direction, which would cause a decrease in the strength of the array laser thermal isolation packaging structure 10.

[0101] Understandably, see [link / reference] Figure 5 The physical isolation of the first trench 17 and the second trench 25, combined with the deep synergy of the active heat dissipation of the microchannel 26, avoids the problem that a single microchannel cannot effectively control the hot spot temperature, thus improving the reliability of the thermal isolation packaging structure 10 of the array laser. Furthermore, the physical isolation of the first trench 17 and the second trench 25, combined with the deep synergy of the active heat dissipation of the microchannel 26, also avoids the problem that a single microchannel cannot effectively isolate the thermal impact of adjacent laser chips 3, effectively suppressing the thermal cascading phenomenon caused by thermal conduction between adjacent laser chips 3.

[0102] Figure 6 for Figure 4 A top view of the heat dissipation structure.

[0103] In some embodiments, see Figure 6 The heat dissipation structure 2 also includes a cover plate 22, which is disposed on the second surface 212 of the heat conduction carrier 21. The cover plate 22 includes a through fluid inlet 271 and a fluid outlet 272.

[0104] Exemplary embodiments of this application do not limit the number, shape, or relative position of the fluid inlet 271 and fluid outlet 272. An embodiment of this application illustrates this by showing the fluid inlet 271 and fluid outlet 272 arranged in parallel, both being rectangular in shape. The fluid inlet 271 and fluid outlet 272 can be used to connect to a closed-loop liquid cooling system. For example, the coolant in the closed-loop liquid cooling system can be deionized water, with a flow rate ranging from 50 mL / min to 100 mL / min.

[0105] For example, the material of the cover plate 22 can be the same as the material of the heat transfer carrier 21. Both can be made of aluminum nitride.

[0106] The heat transfer carrier 21 includes a plurality of spaced-apart microchannels 26, with a fluid inlet 271 and a fluid outlet 272 both exposing at least a portion of the plurality of microchannels 26. For example, coolant can enter from the fluid inlet 271 of the cover plate 22, pass through the plurality of microchannels 26, carry away the heat in the microchannels 26, and then flow out from the fluid outlet 272.

[0107] Understandably, see Figures 1-5 During the operation of the thermal isolation packaging structure 10 for the array laser, due to the through-groove structure of the chip-carrier, the heat of the active layer 13 of the laser chip 3 cannot diffuse laterally, but can only flow vertically Z-direction to the microchannel 26 region. Furthermore, the downward-facing packaging of the first conductive layer 18 of the array laser 1, and the structure where the depth of the microchannel 26 exceeds the bottom of the second trench 25, maximize the shortening of the heat conduction path of the coolant from the active layer 13 to the microchannel 26. The high heat dissipation efficiency of the microchannel 26 quickly carries away the accumulated heat flux, forming a complementary effect of trench resistance in the lateral direction and sparse flow in the vertical direction. Through the physical isolation of the first trench 17 and the second trench 25, and the deep synergy of the active heat dissipation of the microchannel, a dual breakthrough in thermal crosstalk suppression and heat dissipation efficiency is achieved in the thermal isolation packaging structure 10 for the array laser.

[0108] For example, this embodiment improves the thermal crosstalk suppression capability of the array laser 1 by setting a first trench 17 between two adjacent laser chips 3, setting a second trench 25 on the heat conduction carrier 21, filling the second trench 25 with a high thermal resistance material to form a physical thermal isolation layer, and the synergistic effect of the heat dissipation of the microchannel 26 and the air trench.

[0109] For example, see Figures 1-5 In practical applications, the thermal crosstalk phenomenon of the array laser 1 provided by the embodiments of this application is greatly improved, the temperature fluctuation of key parts is significantly reduced, making the performance of the laser chip 3 more stable, and the consistency and stability of output power are greatly improved. This not only improves the working efficiency and reliability of the laser chip 3, but also extends its service life, providing a stable and reliable light source for long-distance, high-speed data transmission in the field of optical communication, and also providing strong support for achieving high-precision, high-quality processing in the field of laser processing, allowing the array laser 1 to operate stably in more complex environments and high-requirement scenarios, and fully leveraging its advantages.

[0110] On the other hand, this application also provides a method for fabricating a thermally isolated packaging structure for an array laser. Figure 7 A flowchart illustrating the fabrication method of the thermally isolated packaging structure for an array laser provided in an embodiment of this application.

[0111] See Figure 7 The preparation method includes the following steps S1 to S3: Step S1: See Figure 2 and Figure 3 An array laser 1 is formed, which includes multiple laser chips 3. A first trench 17 is provided between two adjacent laser chips 3. The first trench 17 separates the active layers 13 of at least two adjacent laser chips 3.

[0112] For example, see Figure 2 The array laser 1 also includes a substrate 11, and a waveguide layer 12, an active layer 13, a grating layer 14, an upper cladding layer 15, and a ridge waveguide 16 sequentially stacked on the substrate 11. For example, the substrate 11 can be an N-type indium phosphide substrate, and the upper cladding layer 15 can be a P-type upper cladding layer.

[0113] For example, see [link to previous article] Figure 2 A waveguide layer 12, an active layer 13, a grating layer 14, and an upper cladding layer 15 can be sequentially grown on a substrate 11 via metal-organic chemical vapor deposition. The active layer 13 consists of a compressively strained indium gallium arsenide phosphide (InGaAsP) quantum well with a tensile strain barrier, and lower and upper InGaAsP separated confined heterostructure layers. By adjusting the composition of the InGaAsP quantum well, a specific photoluminescence wavelength can be achieved. The active layer 13 is the main heat-generating component of the laser chip 3.

[0114] For example, see [link to previous article] Figure 2 After forming the upper cladding 15, a dual-channel system is formed through etching, and a ridge waveguide 16 for transmitting optical waves is formed. The ridge waveguide 16 can confine the laser mode field within the waveguide by the refractive index difference with the air on both sides, thus coupling higher-order spatial modes to the high-loss planar region to achieve single-mode operation. Along the Z direction, the depth of the ridge waveguide 16 can extend to the grating layer 14.

[0115] For example, see [link to previous article] Figure 2 After forming the ridge waveguide 16, a first trench 17 with a width (X direction) of 15μm~25μm, a length (Y direction) consistent with the active layer 13, and a depth that penetrates at least through the active layer 13 can be prepared between the active layers 13 of two adjacent laser chips 3 using photolithography and deep reactive ion etching techniques.

[0116] Along direction Z, the depth of the first trench 17 extends at least through the active layer 13, thereby separating the main heat-generating parts (active layer 13) of two adjacent laser chips 3. In the embodiments of this application, the first trench 17 is illustrated as extending through both the active layer 13 and the waveguide layer 12. Along direction Y, the length of the first trench 17 is the same as the length of the active layer 13, thereby separating two adjacent laser chips 3 in direction Y.

[0117] For example, see [link to previous article] Figure 2After forming the array laser 1, a dicing machine can be used to cut the epitaxial wafer into bare wafers of the array laser 1 along the edge of the first groove 17. For example, the bare wafers can contain 4 to 16 channels. After cutting, residual debris in the first groove 17 can be cleaned with dilute hydrochloric acid. Furthermore, the integrity of the first groove 17 is inspected using an infrared microscope, and defective laser chips 3 are discarded. For example, the defective laser chip 3 can be a chip with edge cracks.

[0118] Step S2: See Figure 4 A heat dissipation structure 2 is formed, which includes a heat conduction carrier 21. The heat conduction carrier 21 includes a first surface 211 and a second surface 212 opposite to each other. The heat conduction carrier 21 also includes a plurality of second grooves 25, which extend from the first surface 211 into the heat conduction carrier 21.

[0119] For example, see Figure 4 The heat transfer carrier 21 also includes microchannels 26 extending from the second surface 212 into the heat transfer carrier 21. The orthographic projection of the microchannel 26 onto the first surface 211 is offset from the orthographic projection of the second groove 25 onto the first surface 211. Furthermore, in the XY direction parallel to the first surface 211, at least a portion of the microchannel 26 is directly opposite the second groove 25.

[0120] For example, the microchannels 26 are distributed in the middle region of two adjacent thermal isolation trenches 27, using a parallel channel array. It can be understood that the depth of the microchannels 26 exceeds the bottom of the second trench 25 on the first surface 211, thereby maximizing the shortening of the heat conduction path from the active layer 13 of the laser chip 3 to the microchannels 26, while avoiding the overlap of the microchannels 26 and the second trench 25 in the Z direction, which would cause a decrease in the strength of the array laser thermal isolation packaging structure 10.

[0121] For example, see [link to previous article] Figure 4 The heat conduction carrier 21 can be made of AlN ceramic. The InP substrate 11 has a matching coefficient of thermal expansion with the AlN ceramic heat conduction carrier 21, which can improve the problem of cracking or bonding interface failure of the laser chip 3.

[0122] The heat conduction carrier 21 of AlN ceramic material has the characteristics of high thermal conductivity, high insulation and low coefficient of thermal expansion. It is prepared by precision etching and metallization process. The heat conduction carrier 21 can realize the functions of trench matching (the first trench 17 and the second trench 25 are matched), heat dissipation of microchannel 26 and electrical signal transmission.

[0123] For example, see [link to previous article] Figure 4 The second trench 25 and microchannel 26 can be formed by photolithography etching.

[0124] For example, the pattern of the second trench 25 corresponding to the first trench 17 on the first surface 211 can be defined by ultraviolet lithography, and the pattern of the microchannel 26 on the second surface 212 can also be defined. The positional deviation between the pattern of the second trench 25 and the first trench 17 is less than or equal to 2 μm, and alignment marks are reserved between the first trench 17 and the second trench 25. The pattern of the microchannel 26 employs a parallel channel array.

[0125] After forming the patterns of the second trench 25 and the microchannel 26, the second trench 25 can be formed by laser etching, and the sidewalls of the second trench 25 can be bombarded with an argon (Ar) ion beam to reduce the roughness of the sidewalls of the second trench 25. For example, along the Z direction, the depth of the second trench 25 formed by etching can range from 5 μm to 8 μm.

[0126] For example, along the Z direction, the etching depth of the microchannel 26 can range from 50 μm to 100 μm, and its depth-to-width ratio can be 8:1. That is, along the X direction, the etching width of the microchannel 26 can range from 6.25 μm to 12.5 μm.

[0127] Since the etching depth of the microchannel 26 is relatively large, an inductively coupled plasma etching machine can be used to form the microchannel 26 array through intermittent etching, thereby avoiding thermal damage. Furthermore, the method described above can improve the flatness of the bottom of the microchannel 26, thus ensuring uniform flow of the coolant.

[0128] For example, a nano-silver sintering interface can also be provided on the inner wall of the microchannel 26, and the thermal resistance of the nano-silver material is less than 0.1℃. cm² / W. By combining the microfluidic channel 26 with the aforementioned nano-silver sintering interface, the vertical thermal resistance of the array laser thermal isolation packaging structure 10 can be reduced from 0.5℃ / W in the conventional scheme to below 0.15℃ / W.

[0129] Understandably, the low thermal conductivity of the first trench 17 forces the heat flux generated by the laser chip 3 to flow only vertically along the Z direction, through the second trench 25, to the area of ​​the heat conduction carrier 21 where the microchannels 26 are located. The high heat dissipation efficiency of the microchannels 26 quickly carries away the accumulated heat flux, forming a complementary effect of the trench blocking the lateral direction and the channel being sparse in the vertical direction.

[0130] For example, see [link to example]. Figure 4 The heat dissipation structure 2 also includes a cover plate 22, which is disposed on the second surface 212 of the heat conduction carrier 21. The cover plate 22 includes a through fluid inlet 271 and a fluid outlet 272. For example, the material of the cover plate 22 can be aluminum nitride, and the thickness of the cover plate 22 can be 100 μm.

[0131] For example, the microchannels 26 can be sealed using an aluminum nitride cover plate 22 bonding process. In the area where the microchannels 26 are located on the second surface 212 of the heat transfer carrier 21, a glass powder solder (melting point 450°C) is applied. After aligning the cover plate 22 with the second surface 212, both are placed in a vacuum bonding furnace (vacuum degree ≤ 10). -3 Pa, heating rate of 5℃ / min, holding time of 30min), thereby achieving flow channel sealing.

[0132] For example, after sealing the microchannel 26, the heat dissipation structure 2 is tested to ensure that the leakage rate is less than or equal to 1×10⁻⁶. -9 Pa*m³ / s. For example, a closed-loop liquid cooling system is connected at the fluid inlet 271 and the fluid outlet 272. The coolant in the closed-loop liquid cooling system can be deionized water, and the flow rate of the deionized water is in the range of 50 mL / min to 100 mL / min. A pressure test is performed on the heat dissipation structure 2 to ensure that there is no leakage of the coolant. The test pressure can be 0.5 MPa, and the test time can be 30 min.

[0133] Step S3: See Figure 1 An array laser 1 is disposed on a first surface 211, and a first groove 17 corresponds to and is connected to a second groove 25.

[0134] It is understandable that, for example, Figure 2 The array laser 1 shown is inverted as follows: Figure 4 On the heat dissipation structure 2 shown, thus forming as Figure 1 The array laser thermal isolation packaging structure 10 is shown. The first trench 17 and the second trench 25 are connected in a one-to-one correspondence, thereby forming a "chip-carrier" through trench array in the array laser thermal isolation packaging structure 10.

[0135] The above-mentioned through-type trench array design prevents the heat from the active layer 13 from spreading laterally when the laser chip 3 is working. Instead, the heat can only enter the heat conduction carrier 21 through the first trench 17 and the second trench 25. This changes the defect of localized thermal resistance concentration in traditional single-chip-level trenches. In the packaging structure 10 provided by the embodiments of this application, a full-link lateral thermal barrier covering the active layer 13, the heat conduction carrier 21, and the heat sink is formed, which extends the heat conduction path between adjacent laser chips 3 by more than three times, improves the lateral heat conduction path of the laser chip 3, and thus enhances the thermal isolation effect between adjacent laser chips 3.

[0136] The method for fabricating an array laser thermally isolated packaging structure provided in the embodiments of this application includes forming an array laser 1, the array laser 1 including a plurality of laser chips 3, a first trench 17 being provided between two adjacent laser chips 3, the first trench 17 separating at least the active layer 13 of two adjacent laser chips 3.

[0137] It is understandable that the active layer 13 is the main heat-generating part of the array laser 1. By setting the first trench 17 between two adjacent laser chips 3, the main heat-generating parts of the two adjacent laser chips 3 can be separated, thereby separating the heat conduction path between the two adjacent laser chips 3 through the first trench 17 and allowing heat to enter the first trench 17, so as to achieve thermal isolation between the two adjacent laser chips 3.

[0138] Furthermore, a heat dissipation structure 2 is formed, which includes a heat conduction carrier 21. The heat conduction carrier 21 includes a first surface 211 and a second surface 212 facing each other. The heat conduction carrier 21 also includes a plurality of second grooves 25, which extend from the first surface 211 into the heat conduction carrier 21. An array laser 1 is disposed on the first surface 211, with one first groove 17 corresponding to and communicating with one second groove 25.

[0139] Understandably, the heat dissipation structure 2 is used to dissipate heat from the array laser 1. The second groove 25 provided on the first surface 211 of the heat conduction carrier 21 corresponds one-to-one with and is connected to the first groove 17. The first groove 17 and the second groove 25 can serve as a thermal barrier, thereby blocking heat conduction between two adjacent laser chips 3.

[0140] In this application, by setting the first trench 17 of the array laser 1 to be connected to the second trench 25 of the heat dissipation structure 2, a full-link lateral thermal barrier covering the active layer 13, the heat conduction carrier 21 and the heat sink is formed, which effectively extends the heat conduction path between adjacent laser chips 3, improves the lateral heat conduction path of the laser chip 3, thereby improving the thermal isolation effect between adjacent laser chips 3, and thus improving the long-term reliability of the array laser thermal isolation packaging structure 10.

[0141] In some embodiments, see Figures 1-4 The process of placing the array laser 1 on the first surface 211 includes the following steps S301 and S302: Step S301: See Figures 2-4 Alignment marks are set on the laser chip 3 and the heat dissipation structure 2 respectively.

[0142] For example, the heat dissipation structure 2 can be fixed on a vacuum adsorption stage, and the alignment marks between the heat dissipation structure 2 and the laser chip 3 can be identified using a charge-coupled device (CCD) vision alignment system. The identification accuracy of the CCD vision alignment system is less than or equal to 1 μm.

[0143] Step S302: See Figure 1 The alignment system identifies the alignment mark and places the array laser 1 on the first surface 211, so that the first groove 17 of the array laser 1 corresponds to and is connected to the second groove 25 of the heat dissipation structure 2.

[0144] For example, the bare die of the array laser 1 can be inverted and placed above the heat dissipation structure 2, that is, the side surface of the array laser 1 with the first groove 17 faces the side surface of the heat dissipation structure 2 with the second groove 25. The position of the array laser 1 is adjusted so that the centerline deviation between the first groove 17 and the second groove 25 is less than or equal to 2μm, and the alignment status of the two can be confirmed in real time by an infrared camera, thereby achieving the alignment and pre-bonding of the array laser 1 and the heat dissipation structure 2.

[0145] It is understood that the width of the first groove 17 of the array laser 1 can be set to be equal to the width of the second groove 25 of the heat dissipation structure 2. Furthermore, through the above steps S301 and S302, the array laser 1 and the heat dissipation structure 2 can be precisely aligned, so that the first groove 17 and the second groove 25 correspond completely. This allows the lateral heat between adjacent laser chips 3 in the first groove 17 to completely enter the second groove 25, thereby further improving the thermal isolation effect of the first groove 17 between adjacent laser chips 3 and further improving the heat dissipation effect of the heat dissipation structure 2.

[0146] For example, see Figure 1 After the array laser 1 is placed on the first surface 211, the first groove 17 and the second groove 25 are connected to form a cavity 4.

[0147] For example, cavity 4 can be filled with high-purity air. Cavity 4 can then be sealed using a sealing process to prevent air convection from weakening its heat insulation effect. Filling cavity 4 with high-purity air can directly block more than 80% of the lateral heat conduction between two adjacent laser chips 3.

[0148] It is understandable that high-purity air has low thermal conductivity. By setting high-purity air in cavity 4, efficient thermal isolation between adjacent laser chips 3 can be achieved, thereby further blocking heat conduction between adjacent laser chips 3, which is beneficial to reducing the temperature of peripheral laser chips 3 and improving the temperature uniformity of multiple laser chips 3.

[0149] For example, in scenarios requiring extreme thermal isolation efficiency, such as forming a CPO light engine, high-purity air can be filled into cavity 4. This high-purity air has a thermal conductivity of only 0.025 W / (m*K), which is 1 / 6000th the thermal conductivity of silicon. By using a sealing process to prevent air convection from weakening the isolation effect, it can directly block more than 80% of lateral heat conduction. Here, "W / (m*K)" is a unit of thermal conductivity, representing the amount of heat transferred per second through one square meter of area when the temperature difference between the two sides is one Kelvin (1°C) in a one-meter-thick material (the unit of heat is watts W).

[0150] Or, for example, see continue to see Figure 1 Furthermore, a filler material, including modified polyimide, can be provided within the cavity 4. It is understood that modified polyimide has high insulation resistance and good mechanical strength. By providing a filler material of modified polyimide within the cavity 4, the support of the first trench 17 and the second trench 25 can be improved, thereby enhancing the mechanical strength of the encapsulation structure 10.

[0151] For example, in scenarios requiring both mechanical strength and insulation, such as forming an industrial-grade array laser 1, the cavity 4 can be filled with modified polyimide. This modified polyimide has a thermal conductivity of 0.25 W / (m*K) and an insulation resistance of 10 Ω·cm. 14 The tensile strength is 150 MPa, measured in Ω*cm. Modified polyimide not only achieves thermal isolation between two adjacent laser chips 3, but also provides structural support for the laser chips 3, preventing edge embrittlement and cracking after etching, thereby improving the structural stability of the array laser 1.

[0152] In some embodiments, see Figures 1-3 The array laser 1 also includes a first conductive layer 18 and a second conductive layer 19 disposed on opposite sides of the active layer 13. The first conductive layer 18 is closer to the heat dissipation structure 2 than the second conductive layer 19. A first trench 17 penetrates the first conductive layer 18 along a third direction Z perpendicular to the first surface 211.

[0153] For example, see Figure 2 The first trench 17 penetrates the first conductive layer 18, the upper cladding layer 15, the grating layer 14, the active layer 13, and the waveguide layer 12.

[0154] For example, see [link to previous article] Figure 2The first conductive layer 18 can be formed by sputtering a metal layer on the surface of the substrate 11 away from the active layer 14, and then by a lift-off process. For example, the first conductive layer 18 can be a stack of three metals: titanium (Ti), platinum (Pt), and gold (Au), wherein the thickness of the titanium layer can be 50 nm, the thickness of the platinum layer can be 100 nm, and the thickness of the gold layer can be 1000 nm. The first conductive layer 18 can serve as the p-side conductive layer of the array laser 1.

[0155] For example, see [link to example]. Figure 2 The side of substrate 11 furthest from the active layer 13 is the back surface of substrate 11. After thinning the back surface of substrate 11 to 100μm~150μm, a second conductive layer 19 can be formed by sputtering a metal layer on the back surface of substrate 11. The second conductive layer 19 can serve as the N-side conductive layer of the array laser 1. Ohmic contact is achieved through rapid thermal annealing. For example, the second conductive layer 19 can be a stack of three metals: gold (Au), germanium (Ge), and nickel (Ni), wherein the thickness of the gold layer can be 1000nm, the thickness of the germanium layer can be 50nm, and the thickness of the nickel layer can be 100nm.

[0156] See Figure 4 The heat dissipation structure 2 also includes a third conductive layer 23 disposed on the first surface 211. Along the third direction Z, the second trench 25 penetrates the third conductive layer 23, and the third conductive layer 23 includes a first part 231 and a second part 232 that are disconnected.

[0157] For example, see [link to example]. Figure 4 A third conductive layer 23 with a thickness ranging from 50 nm to 200 nm can be formed on the first surface 211 by a sputtering process. For example, the material of the third conductive layer 23 can be a stack of three metals: copper, titanium, and gold.

[0158] The third conductive layer 23 can serve as the electroplating underlayer. Next, photoresist is coated across the entire surface of the third conductive layer 23, and electrode and wiring patterns are defined to obtain the disconnected first portion 231 and second portion 232. Then, copper is electroplated to a thickness of 76 μm, and gold is electroplated to a thickness of 1 μm. Afterward, the photoresist is removed, and an annealing process is performed at 200°C for 1 hour to enhance the adhesion of the metal layer.

[0159] For example, see [link to example]. Figure 4 After the third conductive layer 23 is formed, a pad 24 can also be formed on the first part 231. For example, an alloy containing 80% tin and 20% gold is used as solder. The solder is pre-plated on the electrode area of ​​the heat conduction carrier 21, that is, above the first part 231, using an electroplating process. The pattern of the pre-plated solder is completely matched with the shape of the first conductive layer 18.

[0160] The solder has a melting point of 280℃ and a thermal conductivity of 57 W / (m*K). The pad thickness can be 4 μm along the Z-direction.

[0161] For example, the pre-aligned array laser 1 and heat dissipation structure 2 components can be placed in a eutectic machine for eutectic bonding, thereby achieving bonding of the first conductive layer 18 to the first part 231. For example, the eutectic process conditions can be a temperature of 300°C and a holding time of 3 minutes.

[0162] See Figures 1-4 After the array laser 1 is disposed on the first surface 211, the above preparation method further includes: welding the first conductive layer 18 to the first part 231 and bonding the second conductive layer 19 to the second part 232.

[0163] For example, see Figures 1-4 Along direction Z, the first conductive layer 18 of the array laser 2 is mounted toward the heat dissipation structure 2. A gold wire bonding process can be used to electrically connect the first conductive layer 18 to the first part 231 via pads 24. For example, the diameter of the gold wire can be 25 μm. Exemplarily, the second conductive layer 19 of the array laser 2 can be bonded to the metallized wiring of the second part 232.

[0164] For example, see Figures 1-5 In practical applications, the thermally isolated packaging structure 10 for the array laser prepared by the method provided in this application significantly improves the thermal crosstalk phenomenon of the array laser 1, significantly reduces temperature fluctuations in key areas, and makes the performance of the laser chip 3 more stable, greatly improving the consistency and stability of output power. This not only improves the working efficiency and reliability of the laser chip 3, but also extends its service life, providing a stable and reliable light source for long-distance, high-speed data transmission in the field of optical communication, and also provides strong support for achieving high-precision, high-quality processing in the field of laser processing, allowing the array laser 1 to operate stably in more complex environments and demanding scenarios, fully leveraging its advantages.

[0165] Furthermore, the fabrication method provided in the embodiments of this application is highly compatible with existing semiconductor manufacturing processes. For example, trench etching can be performed simultaneously with the grating fabrication process of the DFB laser, without the need for an additional dedicated production line, increasing manufacturing costs by only 10% to 15%. Simultaneously, this design can be directly adapted to the 3D stacked packaging architecture of CPO, connecting the microchannels with the upper-layer optical engine and the lower-layer application-specific integrated circuit (ASIC) chip via through-silicon vias (TSVs), achieving synergistic integration of "optics-electricity-thermal." This provides key technical support for the reliable deployment of high-density, high-power array lasers 1.

[0166] On the other hand, embodiments of this application also provide a laser system. Figure 8 This is a structural block diagram of a laser system provided for an embodiment of this application.

[0167] See Figure 8 The laser system 100 includes an array laser thermally isolated package structure 10 as described in any of the above embodiments and an optical transmission system 200. The optical transmission system 200 is coupled to the array laser thermally isolated package structure 10.

[0168] For example, the optical transmission system 200 may include an optical transmission medium such as an optical fiber, optical waveguide, or free-space optical path for guiding the beam generated by the array laser 1 in the thermally isolated packaging structure 10 of the array laser. By coupling the array laser 1, which has efficient thermal tuning capability, to the optical transmission system 200, the laser system 100 can achieve stable and controllable laser signal transmission and processing.

[0169] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A thermally isolated packaging structure for an array laser, characterized in that, Includes array lasers and heat dissipation structures; The array laser includes multiple laser chips, and a first trench is provided between two adjacent laser chips. The first trench separates the active layers of at least two adjacent laser chips. The heat dissipation structure includes a heat conduction carrier, which includes a first surface and a second surface opposite to each other. The heat conduction carrier also includes a plurality of second grooves, which extend from the first surface into the heat conduction carrier. The array laser is disposed on the first surface, and one of the first grooves and one of the second grooves are correspondingly disposed and connected.

2. The packaging structure according to claim 1, characterized in that, The plurality of laser chips are arranged along a first direction. The first trench includes two opposite edges along the first direction, and the second trench includes two opposite edges along the first direction. The two edges of the first trench and the two edges of the second trench correspond to each other and are connected.

3. The packaging structure according to claim 1, characterized in that, The first trench and the second trench are connected to form a cavity; The cavity is used to store high-purity air; or, The cavity is filled with a filling material.

4. The packaging structure according to claim 1, characterized in that, The heat transfer carrier further includes microchannels that extend from the second surface into the heat transfer carrier. The orthographic projection of the microchannel on the first surface is offset from the orthographic projection of the second groove on the first surface. Furthermore, in a planar direction parallel to the first surface, the microchannel is directly opposite at least a portion of the second trench.

5. The packaging structure according to claim 4, characterized in that, The heat dissipation structure further includes a cover plate disposed on the second surface; the cover plate includes a through fluid inlet and a fluid outlet. The heat transfer carrier includes a plurality of spaced-apart microchannels, with the fluid inlet and the fluid outlet both exposing at least a portion of the plurality of microchannels.

6. The packaging structure according to claim 1, characterized in that, The array laser further includes a first conductive layer and a second conductive layer disposed on opposite sides of the active layer. The first conductive layer is closer to the heat dissipation structure than the second conductive layer. The first trench penetrates the first conductive layer along a third direction perpendicular to the first surface. The heat dissipation structure further includes a third conductive layer disposed on the first surface; along the third direction, the second trench penetrates the third conductive layer; the third conductive layer includes a first part and a second part that are disconnected; The first conductive layer is electrically connected to the first part, and the second conductive layer is electrically connected to the second part.

7. The packaging structure according to claim 1, characterized in that, The array laser also includes a substrate disposed on the side of the active layer away from the heat dissipation structure; The substrate is made of indium phosphide; the heat-conducting carrier is made of aluminum nitride ceramic.

8. A method for fabricating a thermally isolated packaging structure for an array laser, characterized in that, include: An array laser is formed, the array laser comprising a plurality of laser chips, a first trench being provided between two adjacent laser chips, the first trench separating at least the active layers of the two adjacent laser chips; A heat dissipation structure is formed, the heat dissipation structure includes a heat conduction carrier, the heat conduction carrier includes a first surface and a second surface opposite to each other, the heat conduction carrier also includes a plurality of second grooves, the second grooves extending from the first surface into the heat conduction carrier; The array laser is disposed on the first surface, with a first groove corresponding to and connected to a second groove.

9. The preparation method according to claim 8, characterized in that, Deploying the array laser on the first surface includes: Alignment marks are respectively provided on the laser chip and the heat dissipation structure; The alignment system identifies the alignment mark and places the array laser on the first surface, such that the first groove of the array laser corresponds to and communicates with the second groove of the heat dissipation structure.

10. A laser system, characterized in that, include: The array laser thermal isolation packaging structure as described in any one of claims 1 to 7; The optical transmission system is coupled to the thermally isolated packaging structure of the array laser.

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