A two-phase heat dissipation chip package structure integrating a micro-nano porous boiling layer and an embedded heat pipe

Abstract

The application discloses a two-phase heat dissipation chip packaging structure integrated with a micro-nano porous boiling layer and an embedded heat pipe, a single crystal silicon substrate, a front surface of which is formed with an active device layer of an integrated circuit; a micro-nano composite porous boiling layer, which is formed on a back surface of the single crystal silicon substrate; a sealing cover plate, which is bonded to the back surface of the single crystal silicon substrate through a sealing ring and jointly forms a closed steam cavity, an inner wall surface of the sealing cover plate being covered with a cover plate capillary pump core; and an embedded heat pipe, an evaporation section of the embedded heat pipe being communicated with the steam cavity, and a condensation section of the embedded heat pipe extending to outside of the chip packaging, and the embedded heat pipe being internally provided with a heat pipe capillary pump core. The two-phase heat dissipation system is integrated in the chip packaging, the thermal resistance of the thermal interface material between the chip and the heat sink in the traditional packaging is eliminated, more efficient self-driven heat dissipation is realized, and the application is particularly suitable for high-power devices such as CPUs, GPUs and AI chips.

Description

Technical Field

[0001] This invention relates to chip packaging structures and electronic heat dissipation, specifically to a novel chip packaging structure that directly integrates a high-efficiency two-phase boiling heat dissipation system inside the chip. Background Technology

[0002] The rapid development of AI and big data is constantly increasing the demand for computing power. The transistor density and frequency requirements of core components such as CPUs and GPUs are increasing, directly leading to an increase in chip heat flux density. Especially for humanoid robots, in-vehicle computing, and high-density data centers, where overall space is limited, traditional air cooling and external single-phase liquid cooling solutions are approaching their physical limits.

[0003] Current mainstream heat dissipation architectures are limited to a three-layer stack of "chip-TIM-vapor chamber." The thermal conductivity of interface materials (TIMs) such as thermal grease is far inferior to that of metals and silicon. Under high heat flux, interface thermal resistance has become a major bottleneck in heat dissipation. Although embedded microchannel liquid cooling can effectively reduce thermal resistance, its reliance on external pumps, piping, and heat exchange systems makes the system bulky and poses safety hazards such as leakage and short circuits. Therefore, developing a compact, self-powered heat dissipation chip that can completely eliminate interface thermal resistance and requires no external power has become a key issue in breaking through the ceiling of computing power. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a two-phase heat dissipation chip packaging structure that integrates micro-nano porous boiling and built-in heat pipes. This structure utilizes porous boiling enhanced heat transfer technology and built-in heat pipe condensation heat transfer technology to directly transfer the heat generated by the chip. For chip operating scenarios requiring high computational loads, this improves the chip's heat dissipation efficiency and ensures the chip's operational reliability.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A two-phase heat dissipation chip packaging structure integrating a micro / nano porous boiling layer and a built-in heat pipe includes:

[0007] A single-crystal silicon substrate, on the front side of which an active device layer for integrated circuits is formed;

[0008] A micro-nano composite porous boiling layer is formed on the back side of the single-crystal silicon substrate;

[0009] A sealing cover plate is bonded to the back side of the single crystal silicon substrate through a sealing ring, together forming a sealed vapor chamber. The inner wall surface of the sealing cover plate is covered with a cover plate capillary pump core.

[0010] The built-in heat pipe has an evaporation section connected to the vapor chamber and a condensation section extending to the outside of the chip package. The built-in heat pipe is equipped with a heat pipe capillary pump core.

[0011] Cooling components are installed in the condenser section with built-in heat pipes.

[0012] The working fluid is encapsulated within the steam chamber and the built-in heat pipe cavity.

[0013] The capillary pump core of the cover plate is connected to or in contact with the capillary pump core of the heat pipe, forming a continuous capillary path for the reflux of the working fluid.

[0014] Furthermore, the front side of the single-crystal silicon substrate has an integrated circuit structure, and the back side of the single-crystal silicon substrate is processed into a micro-nano composite porous boiling layer.

[0015] Furthermore, the micro-nano composite porous boiling layer includes a micron-scale needle-fin array formed by dry etching, and a nano-scale porous material layer grown on the surface of the micron-scale needle-fin array.

[0016] Furthermore, it also includes a protective shell, installed on the back of the micro-nano composite porous boiling layer, used to cover the micro-nano composite porous boiling layer and a sealing cover.

[0017] Furthermore, the cooling component is one of heat dissipation fins, air-cooled radiators, or liquid-cooled cold plates.

[0018] Furthermore, the working fluid is one of deionized water, an alcohol solution, or a fluorinated liquid with insulating properties.

[0019] Furthermore, the micro-nano composite porous boiling layer, the sealing cover plate, and the built-in heat pipe are all integrated on the back side of the single crystal silicon substrate.

[0020] This invention provides a two-phase heat dissipation chip packaging structure integrating micro / nano porous boiling and a built-in heat pipe. It has the following advantages:

[0021] 1. This invention enables direct heat transfer, eliminating the thermal resistance caused by the direct rubber connection between the chip wafer and the metal plate, and further improving heat dissipation efficiency.

[0022] 2. This invention uses a capillary pump core structure and the gravity of the liquid to achieve liquid reflux, saving energy and improving the structure, eliminating the need for a heavy power pump to achieve reflux.

[0023] 3. The working fluids used in this invention are all insulating materials, such as deionized water, which improves reliability. Attached Figure Description

[0024] Figure 1A schematic diagram of the overall cross-sectional structure of a two-phase heat dissipation chip packaging structure integrating micro-nano porous boiling and built-in heat pipe proposed in this invention.

[0025] Figure 2 This is a partially enlarged schematic diagram of the microstructure of the micro-nano composite porous boiling layer on the back side of the single-crystal silicon substrate in this invention.

[0026] Figure 3 This is a partial structural diagram of the connection between the sealing cover and the built-in heat pipe in this invention.

[0027] 1-Single crystal silicon substrate, 2-Micro-nano composite porous boiling layer, 21-Micron-level needle fin array, 22-Nano-level porous material layer, 3-Sealing cover plate, 32-Vapor chamber, 4-Cover plate capillary pump core, 5-Protective shell, 6-Heat pipe capillary pump core, 7-Built-in heat pipe, 8-Cooling component. Detailed Implementation

[0028] Example 1

[0029] like Figure 1 As shown, the present invention provides a two-phase heat dissipation chip packaging structure integrating a micro-nano porous boiling layer and a built-in heat pipe, including: a single crystal silicon substrate 1, a micro-nano composite porous boiling layer 2, a sealing cover plate 3, a cover plate capillary pump core 4, a heat pipe capillary pump core 6, a built-in heat pipe 7, and a cooling component 8.

[0030] In this embodiment, the front side of the monocrystalline silicon substrate 1 has an active device layer with integrated circuits formed by standard semiconductor processes. The back side of the monocrystalline silicon substrate 1 has a micro / nano composite porous boiling layer 2. Compared with traditional packaging structures, this application directly utilizes the back side of the monocrystalline silicon substrate 1 as a heat dissipation layer. After heat is generated from the active device layer on the front side of the monocrystalline silicon substrate, it is directly conducted through the monocrystalline silicon substrate 1 to the micro / nano composite porous boiling layer 2 on the back side. This completely eliminates the traditional stacking mode of "chip-thermal conductive interface material (TIM)-heat dissipation substrate" and achieves the shortest physical distance and lowest thermal resistance path connection between the heat dissipation structure and the heat source.

[0031] It is important to emphasize that the micro / nano composite porous boiling layer 2 is directly fabricated using deep reactive ion etching (DRIE) to create a micron-scale needle-fin array 21, and a nano-scale porous material layer 22 is fabricated on the surface of the needle-fins using wet chemical etching or deposition processes. This hierarchical structure significantly increases the heat transfer specific surface area for both the micron-scale needle-fin array 21 and the nano-scale porous material layer 22, while providing more vaporization nuclei, thus significantly enhancing boiling heat transfer efficiency. This ensures no contact thermal resistance between the micro / nano composite porous boiling layer 2 and the single-crystal silicon substrate 1, resulting in high mechanical bonding strength and good thermal stability.

[0032] In this embodiment, the sealing cover 3 achieves a permanent and highly airtight bond with the micro-nano composite porous boiling layer 2, which is opposite to the back side of the single-crystal silicon substrate 1, through a sealing ring, forming a sealed vapor chamber 32. This ensures stable resistance to the phase change pressure of the internal working fluid, guarantees long-term sealing reliability, and prevents working fluid leakage. The sealing ring can be formed using methods known in the art, such as metal eutectic bonding, glass powder sintering, or anodic bonding.

[0033] In this embodiment, a window is opened at the end of the sealing cover plate 3 facing away from the single crystal silicon substrate 1, and the inner wall surface of the sealing cover plate 3 at the window is covered with a capillary pump core 4. The capillary pump core 4 can be attached to the inner wall surface of the sealing cover plate 3 in the form of sintered copper powder or etched grooves, which are known in the art.

[0034] In this embodiment, one end of the built-in heat pipe 7 is sealed and nested within the window of the sealing cover plate 3, and a heat pipe capillary pump core 6 is provided on the inner wall of the end near the vapor chamber 32. The heat pipe capillary pump core 6 can be attached to the inner wall surface of the built-in heat pipe 7 using sintered copper powder or etched grooves, which are known in the art. The heat pipe capillary pump core 6 is in close physical contact or overlapped with the cover plate capillary pump core 4, forming a continuous liquid reflux path from the condensing end to the boiling layer.

[0035] It should be added that the section of the built-in heat pipe 7 closest to the vapor chamber 32 is the evaporation section and is connected to the vapor chamber 32. The section of the built-in heat pipe 7 furthest from the vapor chamber 32 is the condensation section, extending to the outside of the chip package. The vapor chamber 32, as the initial space for working fluid vaporization, is directly connected to the evaporation section of the built-in heat pipe 7. This through-flow design ensures that the generated steam can enter the main channel of the heat pipe without obstruction and with low flow resistance, making it a key fluid connection node for steam transport.

[0036] In this embodiment, the key to the heat pipe capillary pump core 6 and the cover plate capillary pump core 4 lies in, for example Figure 3 As shown, the capillary pump core 4 on the inner wall of the sealing cover plate 3 and the heat pipe capillary structure 6 of the built-in heat pipe 7 are in close physical contact or overlap, forming a continuous liquid reflux path from the condensing end to the boiling layer. The pore size of the capillary pump core of the built-in heat pipe 7 is larger than that of the capillary pump core of the sealing cover plate 3, forming a difference in capillary force, which is more conducive to reflux.

[0037] It should be added that, at the condenser end, the relatively large pores of the heat pipe capillary structure mainly serve the function of liquid collection and distribution; in the cover plate and boiling layer region near the heat source, the smaller pores of the capillary structure provide stronger capillary suction force, which together drive the liquid to overcome flow resistance and flow back to the boiling point where the working fluid is most needed.

[0038] In this embodiment, a protective shell 5 is also installed on the back of the micro-nano composite porous boiling layer 2, covering the micro-nano composite porous boiling layer 2 and the sealing cover plate 3. The protective shell 5 protects the relatively fragile microstructure of the micro-nano composite porous boiling layer 2 and the sealing cover plate 3, preventing the needle fins from breaking or the nanoporous layer from peeling off due to stress caused by external pressure, vibration or internal working fluid phase change during subsequent cover plate bonding, vacuum liquid injection, transportation or use.

[0039] In this embodiment, the cooling component 8 is one of the following: heat dissipation fins, air-cooled radiator, or liquid-cooled plate.

[0040] In this embodiment, a certain degree of vacuum is created in the vapor chamber 32 and the built-in heat pipe 7, and an appropriate amount of working fluid is injected. Considering the safety of the encapsulation structure, the working fluid preferably uses a fluorinated liquid or deionized water with good insulating properties.

[0041] Example 2

[0042] This embodiment is based on the working principle of this application, which is based on phase change heat transfer and capillary actuation:

[0043] 1. Endothermic Vaporization: The active device layer of the chip generates a large amount of heat during operation. This heat is directly conducted through the single-crystal silicon substrate 1 to the micro / nano composite porous boiling layer 2 on the back side. This eliminates the need for traditional TIM thermal interface materials, breaks the traditional packaging structure, and greatly reduces thermal resistance. Subsequently, the working fluid boils under heat in the micro / nano porous structure, which provides more vaporization nuclei, generating a large amount of steam.

[0044] 2. Steam transport: The generated high-pressure steam, driven by the pressure difference, enters the built-in heat pipe 7 from the steam chamber 32 and flows rapidly to the condensation section that extends to the outside.

[0045] 3. Condensation and heat dissipation: A cooling component 8 (such as air-cooled fins or water-cooled plates) is installed outside the condensation section. Steam releases latent heat as it flows through this section and condenses into liquid.

[0046] 4. Self-driven reflux: The condensed liquid working fluid, under the strong capillary force generated by the heat pipe capillary structure 6 and the capillary pump core 4 of the cover plate, and with the assistance of gravity (depending on the installation direction), automatically flows back to the boiling layer 2 on the back of the single crystal silicon substrate 1, thus completing the cycle.

[0047] Example 3

[0048] This embodiment is based on Embodiment 1 and provides the fabrication steps of the heat dissipation chip packaging structure, as follows:

[0049] Wafer fabrication: The CMOS process is completed on the front side of the wafer to reduce its thickness.

[0050] Backside modification: Photolithography and dry etching are performed on the backside of the wafer to form micron-sized needle fins; subsequently, a nanoporous layer is formed by chemical oxidation or deposition.

[0051] Cover plate encapsulation: Prepare a sealing cover plate 3 with a capillary core and bond it to the back side of the wafer for sealing.

[0052] Heat pipe integration and liquid injection: Install the prefabricated heat pipe to the cover plate interface, evacuate and inject insulating working fluid, and finally seal.

Claims

1. A two-phase heat dissipation chip packaging structure integrating a micro / nano porous boiling layer and a built-in heat pipe, characterized in that, include: A single-crystal silicon substrate (1) has an active device layer of integrated circuits formed on its front side; A micro-nano composite porous boiling layer (2) is formed on the back side of the single crystal silicon substrate (1); The sealing cover plate (3) is bonded to the back of the single crystal silicon substrate (1) through the sealing ring, and together they enclose a sealed vapor chamber (32). The inner wall of the sealing cover plate (3) is covered with a cover plate capillary pump core (4). Built-in heat pipe (7), the evaporation section of the built-in heat pipe (7) is connected to the vapor chamber (32), the condensation section of the built-in heat pipe (7) extends to the outside of the chip package, and a heat pipe capillary pump core (6) is provided inside the built-in heat pipe (7). Cooling component (8) is installed in the condensation section of the built-in heat pipe (7); The working fluid is encapsulated in the steam chamber (32) and the cavity of the built-in heat pipe (7); The capillary pump core (4) of the cover plate is connected to or in contact with the capillary pump core (6) of the heat pipe to form a continuous capillary path for the reflux of the working fluid.

2. The two-phase heat dissipation chip packaging structure integrating a micro / nano porous boiling layer and a built-in heat pipe according to claim 1, characterized in that, The single-crystal silicon substrate (1) has an integrated circuit structure on the front side, and the back side of the single-crystal silicon substrate (1) is processed into a micro-nano composite porous boiling layer (2).

3. The two-phase heat dissipation chip packaging structure integrating a micro / nano porous boiling layer and a built-in heat pipe according to claim 1, characterized in that, The micro-nano composite porous boiling layer (2) includes a micron-scale needle-fin array (21) formed by dry etching, and a nano-scale porous material layer (22) grown on the surface of the micron-scale needle-fin array (21).

4. The two-phase heat dissipation chip packaging structure integrating a micro / nano porous boiling layer and a built-in heat pipe according to claim 1, characterized in that, It also includes a protective shell (5), which is installed on the back of the micro-nano composite porous boiling layer (2) to cover the micro-nano composite porous boiling layer (2) and a sealing cover plate (3).

5. The two-phase heat dissipation chip packaging structure integrating a micro / nano porous boiling layer and a built-in heat pipe according to claim 1, characterized in that, The cooling component (8) is one of the following: heat dissipation fins, air-cooled radiator, or liquid-cooled plate.

6. The two-phase heat dissipation chip packaging structure integrating a micro / nano porous boiling layer and a built-in heat pipe according to claim 1, characterized in that, The working medium is one of deionized water, alcohol solution, or fluorinated liquid with insulating properties.

7. The two-phase heat dissipation chip packaging structure integrating a micro / nano porous boiling layer and a built-in heat pipe according to claim 1, characterized in that, The micro-nano composite porous boiling layer (2), the sealing cover plate (3) and the built-in heat pipe (7) are all integrated on the back side of the single crystal silicon substrate (1).

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