Silicon-based structure of micro heat pipe and processing technology
By employing silicon-based micro heat pipes in microelectronic devices, integrating liquid wicks and photolithography etching processes, the problems of increased thickness and interface peeling associated with traditional metal micro heat pipes are solved, achieving both thinness and efficient heat dissipation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-03-24
AI Technical Summary
Traditional metal micro heat pipes increase thickness in microelectronic devices, which goes against the original intention of thin and light design. They also have problems such as interface peeling and differences in thermal expansion coefficients, which affect reliability and heat dissipation efficiency.
The silicon-based micro heat pipe includes a silicon-based chip substrate and a glass sheet, and integrates a liquid wick. The liquid wick consists of an evaporation section, an insulation section and a condensation section. The working fluid channels are arranged in an array. Combined with photolithography and etching processes, the interfacial thermal resistance is eliminated, and the capillary force and heat dissipation surface area are enhanced.
It achieves the miniaturization and efficient heat dissipation of microelectronic devices, improves heat transfer performance and reliability, solves the problem of differences in interface thermal resistance and thermal expansion coefficient, and is suitable for high temperature and high humidity environments.
Smart Images
Figure CN121729078A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of micro heat pipe technology, and in particular to a silicon-based structure and processing technology for a micro heat pipe. Background Technology
[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.
[0003] In the wave of microelectronics technology iterating towards high density and high integration, microelectronic devices are developing with "extreme thinness" as their core goal—breaking through from millimeter-level thickness to micrometer-level thickness, and evolving from independent packaging to integrated "chip-module-system" integration. Under this trend, two core contradictions are becoming increasingly prominent: on the one hand, the continuous reduction in device size has led to an exponential increase in internal heat flux density, with the local heat flux density of some microchips exceeding 1000 W / cm², far exceeding the load-bearing limit of traditional heat dissipation solutions; on the other hand, the stringent limitations on the overall size and weight of devices imposed by "thinness" have completely compressed the installation space of traditional heat dissipation components, forcing heat dissipation solutions to transform towards deep integration at the "chip level" and "bare die level".
[0004] In traditional heat dissipation methods, microelectronic devices require a multi-layered assembly structure of "chip-thermal interface material-heat sink / heat pipe" to achieve heat transfer. However, the presence of interfacial thermal resistance becomes the core bottleneck for heat dissipation. More importantly, although traditional metal micro heat pipes have efficient phase change heat transfer capabilities, they need to be additionally packaged and bonded to the chip. This not only increases the thickness, violating the original intention of thin and light design for micro devices, but also, due to the difference in thermal expansion coefficients between metal and silicon-based chips, is prone to reliability risks such as interface peeling and cracking during temperature cycling. This problem directly shortens the lifespan of micro portable devices, especially in those with frequent start-stop cycles.
[0005] Meanwhile, silicon-based materials, as the core substrate for manufacturing microelectronic devices, are increasingly well-suited to the demands for "thinness and integration": First, the micro-nano fabrication technology for silicon-based chips is highly mature, allowing for the direct etching of micron-level micro heat pipes and liquid wick structures on or inside the chip substrate without additional packaging space. This achieves zero-gap integration of the heat dissipation structure and the chip substrate, eliminating the interfacial thermal resistance of traditional assembly at its source. Furthermore, the overall thickness can be controlled to increase by no more than 600μm from the original chip thickness, perfectly matching the thinness requirements of micro-devices. Second, although silicon's thermal conductivity is slightly lower than copper, it is sufficient to meet the local heat conduction requirements of micro-devices. Its excellent chemical stability, high-temperature resistance, and lighter weight make it suitable for the long-term high-temperature operation of chips. More importantly, this design can be mass-produced using existing semiconductor production lines without the need for additional dedicated equipment, significantly reducing the R&D and production costs of heat dissipation solutions for micro-devices.
[0006] Heat pipes, as highly efficient phase-change heat transfer elements, have replaced traditional non-phase-change cooling methods and are widely used in the field of electronic component heat dissipation. However, as microelectronic devices develop towards higher density and miniaturization, ordinary heat pipes suffer from problems such as poor size adaptability, insufficient heat flux density, and large space occupation. Micro heat pipes, with their miniaturized structure, can be precisely embedded inside devices, matching limited installation space; they can address the problem of localized overheating under high power density, rapidly transferring concentrated heat; and they possess highly efficient phase-change heat transfer characteristics, with thermal resistance far lower than ordinary heat pipes. They can meet the stringent requirements of microelectronic devices for heat dissipation efficiency, space utilization, and thermal uniformity, ensuring stable device operation; and have become a new trend in heat dissipation for microelectronic devices.
[0007] The wick is the core component of a micro heat pipe, its main function being to drive the condensed liquid working fluid back to the evaporation section via capillary force, maintaining the working fluid circulation. Common structural types include porous media types (such as sintered metal powder cores and porous ceramic cores), grooved types (such as rectangular and triangular microgroove arrays), and composite structures (such as a combination of grooves and sintered porous layers), each suited to different working fluids and operating conditions. Among these, the grooved type utilizes capillary force for reflux through etched grooves on the inner wall. It is lightweight, has a fast thermal response, and high permeability, perfectly aligning with the trend towards thinner and lighter electronic devices. However, its capillary force is weak, making it susceptible to gravity and unable to simultaneously meet the performance requirements of capillary enhancement and the trend towards thinner designs. Capillary suction determines the working fluid reflux capability, while porosity and permeability affect the working fluid flow efficiency. Materials compatible with the micro heat pipe substrate are often used, and the micro heat pipe is fabricated using precision processes such as photolithography, laser processing, and sintering to achieve precise control over the miniaturized structure.
[0008] While traditional metal micro heat pipes possess efficient phase change heat transfer capabilities, they require additional encapsulation before bonding to the chip, increasing their thickness and contradicting the original intention of miniaturized devices to be thin and lightweight. Furthermore, the difference in thermal expansion coefficients between metal and silicon-based chips can easily lead to reliability risks such as interface peeling and cracking during temperature cycling. This problem can directly shorten the lifespan of devices, especially in micro portable devices that frequently start and stop. Summary of the Invention
[0009] In view of the shortcomings of existing technologies, the purpose of this invention is to provide a silicon-based structure for micro heat pipes, which provides a new solution for the thinning and integration of heat dissipation in micro electronic devices and chips.
[0010] To achieve the above objectives, the present invention is implemented through the following technical solution: A silicon-based structure for a micro heat pipe includes a silicon-based chip substrate and a glass sheet. The silicon-based chip substrate and the glass sheet are bonded together. A liquid wick is integrated on the side of the silicon-based chip substrate facing the glass sheet. The liquid wick includes an evaporation section, an insulation section, and a condensation section connected in sequence. The lengths of the insulation section and the condensation section are greater than the length of the evaporation section. The evaporation section includes multiple working fluid channels, each of which is connected to the insulation section. The multiple working fluid channels are arranged in an array, and adjacent working fluid channels are connected.
[0011] In the silicon-based structure of the micro heat pipe described above, multiple working fluid channels are arranged in multiple rows and columns, with the distance between two adjacent rows of working fluid channels being 0.06mm-0.1mm and the distance between two adjacent columns of working fluid channels being 0.12mm-0.18mm.
[0012] In the silicon-based structure of the micro heat pipe described above, the working fluid channel has a circular cross-sectional shape, and the diameter of the working fluid channel cross-section is 0.02mm-0.05mm.
[0013] In the silicon-based structure of the micro heat pipe described above, the sum of the lengths of the adiabatic section and the condensation section is 2-3 times the length of the evaporation section.
[0014] As described above, in a silicon-based structure of a micro heat pipe, both the insulating section and the condensing section include multiple flow channels. Two adjacent flow channels are arranged in parallel with each other, and branch channels are arranged on both sides of the flow channels. The branch channels are connected to the flow channels at a set angle.
[0015] In the silicon-based structure of the micro heat pipe described above, the angle between the branch channel and the flow channel ranges from 20° to 60°, and the vertical distance between the end of the branch channel away from the flow channel and the flow channel is 0.05mm to 0.07mm.
[0016] In the silicon-based structure of the micro heat pipe described above, the angle between the branch channel and the flow channel is 40°, and the ratio of the vertical distance between the end of the branch channel away from the flow channel and the flow channel to the distance between two adjacent flow channels is 1 / 3. At this time, the thermal conductivity of the silicon-based micro heat pipe structure is optimal.
[0017] In the silicon-based structure of the micro heat pipe described above, the thickness of the glass sheet is 0.4mm-0.6mm; The thickness of the silicon-based chip substrate is 0.5mm-0.7mm; The inlet side of the evaporation section is connected to a liquid inlet channel, and there are multiple liquid inlet channels. The outlet side of the condensation section is connected to a liquid outlet channel, and there are multiple liquid outlet channels.
[0018] Secondly, the present invention also provides a silicon-based structure for a micro heat pipe and a fabrication process for the silicon-based structure of a micro heat pipe, comprising the following: Photolithography on silicon-based chip substrates: using photosensitive materials as an intermediary, the light is transferred to the front side of the silicon-based chip substrate through an illumination pattern; Etching: Etching the liquid wick on the front side of the silicon-based chip substrate. The liquid wick includes a connected evaporation section, an insulation section, and a condensation section. The evaporation section includes multiple working fluid channels, each of which is connected to the insulation section. The multiple working fluid channels are arranged in an array, and adjacent working fluid channels are connected. The silicon-based chip substrate is bonded to a glass sheet to form the original component of the silicon-based micro heat pipe structure.
[0019] The silicon-based structure of a micro heat pipe, as described above, includes the following processing steps after bonding the silicon-based chip substrate to the glass sheet: The thickness of the formed original part is measured. If the silicon-based chip substrate is greater than 0.645 mm, the back side of the silicon-based chip substrate is thinned. Polishing and cleaning of silicon-based chip substrates; Silicon dioxide deposition: Depositing a silicon dioxide layer of a predetermined thickness on the back side of a silicon-based chip substrate; Photolithography is performed on the back side of the silicon-based chip substrate; Deposition of Cr and Pt: A Cr layer of a predetermined thickness is deposited on the back side of a silicon-based chip substrate, followed by the deposition of a Pt layer of a predetermined thickness. Peeling: Soak in acetone for a set time, then perform ultrasonic peeling.
[0020] Secondary photolithography on the back: Secondary photolithography is performed on the back of the silicon-based chip substrate to achieve photolithography of the liquid inlet channel and liquid outlet channel of the silicon-based micro heat pipe structure; Etching: Etching the back side of a silicon-based chip substrate to form a chip.
[0021] The beneficial effects of the present invention are as follows: This invention, through the overall structural design that combines a silicon-based chip substrate and a glass sheet, and sets up a liquid-absorbing core on one side of the silicon-based chip substrate, solves the core bottleneck of interface thermal resistance in traditional microelectronic devices and the problem of differences in thermal expansion coefficients of different materials for heat dissipation. It provides a new solution for the thinning and integration of heat dissipation in microelectronic devices and chips.
[0022] The micro heat pipe structure provided by this invention includes an evaporation section, an insulation section, and a condensation section connected in sequence. The evaporation section includes multiple working fluid channels, each of which is connected to the insulation section. The multiple working fluid channels are arranged in an array, with adjacent working fluid channels connected. The array arrangement of the working fluid channels results in a larger heating area, allowing the liquid to evaporate quickly. Furthermore, the interconnection between adjacent working fluid channels facilitates the rapid distribution of the evaporated gaseous working fluid to the various flow channels of the insulation section. With this structure, the gas-liquid circulation path of the evaporation section is shorter, and the internal liquid replenishment relies on a thick liquid film on the sidewall, while liquid evaporation occurs on the other sidewall. Therefore, the circulation resistance between the internal liquid evaporation and gas condensation is smaller, which accelerates the circulation speed and improves the heat transfer performance of the micro heat pipe.
[0023] In this invention, both the adiabatic section and the condensation section include multiple flow channels, with branch channels set on both sides of the flow channels. The branch channels are connected to the flow channels at a set angle, thus forming a capillary wick structure. This enhances the capillary force and liquid directional transport capability of the micro heat pipe, increases the heat dissipation surface area, and increases the heat exchange area with the surrounding fluid. It solves the problems of small heat dissipation surface area and poor temperature uniformity caused by the limited thickness of the micro heat pipe design, and achieves lightweight, low-cost, and efficient heat dissipation. It also improves the working fluid condensation rate, the condensation working fluid transport rate, and the ability of the wick material to pump the liquid phase working fluid.
[0024] The overall structure of this invention, when the condensed liquid fills the groove, will form a gradually thickening liquid film on the inner wall of the connecting channel. When the liquid film thickens to a certain extent, the liquid will gather into a liquid column that fills the connecting channel. This shows that the structure plays a certain role in promoting the condensation of the micro heat pipe and can improve the condensation rate. Attached Figure Description
[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0026] Figure 1 This is a schematic diagram of a silicon-based structure of a micro heat pipe according to one or more embodiments of the present invention.
[0027] Figure 2 This is an enlarged schematic diagram of the adiabatic section and the condensation section in a silicon-based structure of a micro heat pipe according to one or more embodiments of the present invention.
[0028] Figure 3(a) shows the operating temperature of existing parallel channel micro heat pipes at different power levels.
[0029] Figure 3(b) shows the operating temperature of a silicon-based micro heat pipe structure according to one or more embodiments of the present invention at different power levels.
[0030] Figure 4(a) is a schematic diagram of the microchannel in the early stage of condensation in a silicon-based structure of a micro heat pipe according to one or more embodiments of the present invention.
[0031] Figure 4(b) is a schematic diagram of the microchannel in the mid-condensation stage of a silicon-based structure of a micro heat pipe according to one or more embodiments of the present invention.
[0032] Figure 4(c) is a schematic diagram of the visualization of the microchannel in the later stage of condensation in a silicon-based structure of a micro heat pipe according to one or more embodiments of the present invention.
[0033] Figure 5 This is a cross-sectional schematic diagram of the evaporation section in a silicon-based structure of a micro heat pipe according to one or more embodiments of the present invention.
[0034] Figure 6 This is a test diagram of the thermal conductivity between the branch channel and the flow channel in the evaporation section of a silicon-based structure of a micro heat pipe according to one or more embodiments of the present invention, at different tilt angles.
[0035] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.
[0036] The components are: 1. Liquid inlet channel, 2. Evaporation section, 3. Insulation section and condensation section, 4. Liquid outlet channel, 5. Flow channel, 6. Branch channel, and 7. Working fluid channel. Detailed Implementation
[0037] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. As described in the background section, existing metal micro heat pipes for heat dissipation of silicon-based chips increase the chip thickness and are prone to problems such as interface peeling and cracking. In order to solve the above technical problems, this invention proposes a silicon-based structure for micro heat pipes.
[0039] Example 1 In a typical embodiment of the present invention, reference is made to Figure 1As shown, a silicon-based structure of a micro heat pipe includes a silicon-based chip substrate and a glass sheet. The silicon-based chip substrate and the glass sheet are bonded together. A liquid wick is integrated on the side of the silicon-based chip substrate facing the glass sheet. The liquid wick includes an evaporation section 2, an adiabatic section, and a condensation section 3 connected in sequence. The lengths of the adiabatic section and the condensation section 3 are greater than the length of the evaporation section 2. The evaporation section 2 includes multiple working fluid channels 7, each of which is connected to the adiabatic section. The multiple working fluid channels are arranged in an array, and adjacent working fluid channels 7 are connected, which facilitates the rapid distribution of the evaporated gas working fluid to each channel of the adiabatic section. This makes the gas-liquid circulation path shorter, and the internal liquid replenishment relies on the thick liquid film on the sidewall. The evaporation of the liquid occurs on the other sidewall, so the circulation resistance between the evaporation of the internal liquid and the condensation of the gas is smaller. This speeds up the circulation and improves the heat transfer performance of the micro heat pipe.
[0040] In this embodiment, the sum of the lengths of the adiabatic section and the condensing section 3 is 2-3 times the length of the evaporating section 2. For example, the length of the evaporating section 2 is 9 mm, and the sum of the lengths of the adiabatic section and the condensing section 3 is 24 mm. The lengths of the adiabatic section and the condensing section 3 are the same, which can both be 12 mm.
[0041] refer to Figure 5 As shown, multiple working medium channels 7 are arranged in multiple rows and columns. The distance between two adjacent rows of working medium channels 7 is 0.06mm-0.1mm, specifically 0.08mm, and the distance between two adjacent columns of working medium channels 7 is 0.12mm-0.18mm, specifically 0.15mm.
[0042] Specifically, the working fluid channel 7 has a circular cross-sectional shape. Compared with a rectangular channel, the cylindrical array has a larger heating area, allowing the liquid to evaporate quickly. The diameter of the working fluid channel 7 at its cross-section is 0.02mm-0.05mm, specifically 0.04mm.
[0043] It should be noted that designing the evaporation section 2 as a cylindrical array can improve the heat transfer performance of the micro heat pipe by increasing the evaporation efficiency, promoting rapid gas circulation to the condensation section, shortening the heat pipe start-up time, and accelerating the circulation speed while ensuring timely reflux in the condensation section. Compared to rectangular channels, the cylindrical array has a larger heating area, allowing for rapid liquid evaporation. Furthermore, adjacent cylindrical channels are interconnected, which facilitates the rapid distribution of the evaporated gaseous working fluid into each channel—something that rectangular channels cannot achieve. This is because the gas-liquid circulation path is shorter, and the internal liquid replenishment relies on a thick liquid film on the sidewalls, while liquid evaporation occurs on the other sidewall. Therefore, the circulation resistance between internal liquid evaporation and gas condensation is lower, which accelerates the circulation speed and improves the heat transfer performance of the micro heat pipe.
[0044] In this embodiment, the thickness of the glass sheet is 0.4mm-0.6mm, specifically 0.5mm; the thickness of the silicon-based chip substrate is 0.5mm-0.7mm. It is easy to understand that the inlet side of the evaporation section 2 is connected to the liquid inlet channel 1. There are multiple liquid inlet channels 1, which converge to form an inlet pipe with a radius of 0.5 mm. The outlet side of the condensation section is connected to the liquid outlet channel. There are multiple liquid outlet channels, which converge to form an outlet pipe with a radius of 0.5 mm. The side liquid inlet channel, the side liquid outlet channel and the side of the silicon-based chip substrate are spaced 0.5 mm apart.
[0045] It's important to explain that integrating micro heat pipes onto a silicon-based chip substrate completely eliminates interfacial thermal resistance, allowing core chip heat to be directly conducted to the evaporation section of the micro heat pipe, shortening the heat transfer path by more than 50%. Simultaneously, leveraging existing silicon-based micro / nano fabrication processes, evaporation sections, high-capillary-force adiabatic sections, and condensation sections can be etched onto the silicon-based chip substrate, increasing the heat dissipation surface area and significantly enhancing heat exchange efficiency. This perfectly meets the demands for thinner and lighter designs, requiring only an increase in the thickness of the glass sheet (500μm, or 0.5mm) on top of the silicon-based chip substrate. The overall increase in thickness is less than or equal to 600μm (0.6mm) from the original silicon-based chip substrate thickness, fully meeting the requirements for thinner and lighter micro-devices. Furthermore, silicon-based materials exhibit excellent chemical stability, are not easily oxidized or corroded in high-temperature and high-humidity environments, and have a low rate of heat dissipation performance degradation.
[0046] refer to Figure 2 As shown, both the insulation section and the condensation section 3 include multiple flow channels 5. Two adjacent flow channels 5 are arranged parallel to each other. The width of the flow channel 5 is 0.03mm. Branch channels 6 are arranged on both sides of the flow channel 5. The branch channels 6 are connected to the flow channel 5 at a set angle. The angle between the branch channels 6 and the flow channel 5 is in the range of 20°-60°. The vertical distance between the end of the branch channel 6 away from the flow channel and the flow channel 5 is 0.05mm-0.07mm, specifically 0.06mm.
[0047] refer to Figure 6 As shown, various wick structures with different structural angles and widths were designed, and the thermal conductivity of these structures with micro heat pipes on silicon-based structures was tested. The equivalent thermal conductivity diagram shows that the thermal conductivity of the silicon-based micro heat pipe is optimal when the structural angle is 40° and the structural width is 1 / 3.
[0048] The main factors affecting the performance of micro heat pipes are: evaporation efficiency of the evaporation section, condensation efficiency of the condensation section, gas-liquid circulation rate, and liquid working fluid reflux capability. Branch channels 6 are set on both sides of the flow channel 5 to form a capillary wick structure. The capillary wick structure effectively solves the problems of small capillaries, susceptibility to gravity, low heat transfer efficiency, and uneven heat pipe temperature distribution in grooved micro heat pipes. It provides an efficient heat conduction and fluid transport path, improving the working fluid condensation rate, condensed working fluid transport rate, and the ability of the wick material to pump liquid working fluid.
[0049] Figure 3(a) shows the operating temperature of the existing parallel channel micro heat pipe at different power levels, and Figure 3(b) shows the operating temperature of the silicon-based structure of the micro heat pipe at different power levels. T1, T2, and T3 are axially equidistant temperature measurement points in the evaporation section; T4, T5, and T6 are axially equidistant temperature measurement points in the adiabatic section; T7, T8, and T9 are axially equidistant temperature measurement points in the condensation section; the heating power is the DC power supply power. Figure 3(b) shows that when the heating power increases, the operating temperature of the micro heat pipe first increases sharply, then the rate of increase slows down, and finally reaches a stable state, exhibiting significant thermal response characteristics. Under any heating power, the temperature curve shows a stable characteristic without drastic temperature fluctuations. With the increase of heating power, the operating temperature curve shows a step-like upward trend, reflecting the regulation process of the internal vapor-liquid circulation of the micro heat pipe under different heating powers, as well as its flexible response capability to heat changes.
[0050] A comparison of Figures 3(a) and 3(b) reveals that the overall temperature of the parallel channel micro heat pipe without branch channels is generally higher during operation. When the heating power P = 1.8 W, its highest temperature reaches 115 °C, while the highest temperature of the silicon-based structure with branch channels is 110 °C, which is 5 °C lower than the former. This indicates that the silicon-based structure with branch channels plays an important role in improving heat transfer performance.
[0051] Referring to Figures 4(a), 4(b), and 4(c), a visual observation of the silicon-based structure with micro heat pipes reveals a more pronounced wetting effect within the condensation section. A small amount of liquid can be observed at the corresponding groove. As the micro heat pipe continues to operate, liquid condensation preferentially occurs inside the groove. Once the condensed liquid fills the groove, it forms a gradually thickening liquid film on the inner wall of the channel. When the liquid film thickens to a certain extent, the liquid converges into a liquid column filling the channel. This indicates that the overall structure promotes the condensation of the micro heat pipe and can improve the condensation rate.
[0052] Example 2 This embodiment provides a fabrication process for a silicon-based structure of a micro heat pipe, including the following: Front-side photolithography: The front-side photolithography of silicon-based chip substrates is performed. The core of photolithography technology lies in using photosensitive materials (usually photoresist) as an intermediary to transfer the illumination pattern to the surface of the silicon wafer (a 6-inch single-sided polished silicon wafer with a thickness of 625μm), thereby achieving high-precision pattern definition of the silicon-based chip substrate.
[0053] Etching: A dry etching process was used to etch the front side of the silicon-based chip substrate (STS). The wicking core (the parallel channels of the adiabatic and condensation sections are 120 μm wide and 60 μm high; the width d and tilt angle α of the silicon-based micro heat pipe wicking core structure are variable, forming a series of micro heat pipes with different structural parameters; the evaporation section has uniformly distributed micron-sized pillars with a diameter of 40 μm, a height of 60 μm, a lateral center-to-center distance of 80 μm, and a longitudinal center-to-center distance of 150 μm). After etching, ultrasonic cleaning with acetone and isopropanol was performed to remove photoresist residue.
[0054] Bonding: The etched silicon-based chip substrate is bonded to a glass sheet (a 6-inch double-polished glass sheet with a thickness of 500μm) to form a closed silicon-based micro heat pipe structure.
[0055] Thinning: The thickness of the glass sheet and the silicon-based chip substrate is accurately measured using a thickness gauge. If the thickness of the silicon-based chip substrate is greater than 645μm, the back side of the silicon-based chip substrate is then thinned to reduce its thickness to below 645μm. Polishing: The silicon-based chip substrate is polished for a set time, such as 30 minutes, reducing the total thickness of the silicon-based chip substrate to 635 μm. Then, ultrasonic cleaning is performed using acetone and isopropanol to ensure that the surface is clean and free of residue.
[0056] Silicon dioxide deposition: A silicon dioxide layer with a set thickness, such as 500 nm, is deposited on the back side of the silicon-based chip substrate. This step can prevent the conductivity of silicon from affecting the accuracy of subsequent Pt resistance measurements.
[0057] Backside photolithography: Photolithography is performed on the side of the silicon-based chip substrate away from the glass sheet to facilitate the subsequent placement of Pt resistors on the back side of the silicon-based chip substrate.
[0058] Deposition of Cr (chromium) and Pt (platinum): A Cr layer with a set thickness of 10 nm is deposited on the back side of a silicon-based chip substrate, followed by a Pt layer with a set thickness of 100 nm.
[0059] Stripping: Immerse the silicon-based chip substrate in acetone for a set time, such as 2 hours, and then perform ultrasonic stripping.
[0060] Secondary photolithography on the back side: Secondary photolithography is performed on the back side (the side away from the glass) of the silicon-based chip substrate to determine the liquid inlet channel and liquid outlet channel.
[0061] Etching: The back side of the silicon-based chip substrate is etched to a thickness of 120 μm. Subsequently, ultrasonic cleaning is performed using acetone, isopropanol and anhydrous ethanol to remove photoresist residue on the surface of the liquid inlet channel.
[0062] Integrating micro heat pipes into silicon-based chip substrates completely eliminates interfacial thermal resistance, allowing core heat to be directly conducted to the evaporation section of the micro heat pipes, shortening the heat transfer path by more than 50%. Simultaneously, leveraging silicon-based micro-nano fabrication processes, high-density micro heat pipe arrays and high-capillary-force wicks can be etched onto the silicon-based chip substrate, increasing the heat dissipation surface area and significantly enhancing heat exchange efficiency.
[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A silicon-based structure of micro heat pipes, characterized in that, It includes a silicon-based chip substrate and a glass sheet, with the silicon-based chip substrate and the glass sheet bonded together. A liquid-absorbing core is integrated on the side of the silicon-based chip substrate facing the glass sheet. The liquid-absorbing core includes an evaporation section, an insulation section, and a condensation section connected in sequence. The length of the insulation section and the condensation section is greater than the length of the evaporation section. The evaporation section includes multiple working fluid channels, each of which is connected to the insulation section. The multiple working fluid channels are arranged in an array, and adjacent working fluid channels are connected.
2. A micro heat pipe structure based on silicon as claimed in claim 1, wherein, The multiple working medium channels are arranged in multiple rows and columns, with the distance between two adjacent rows of working medium channels being 0.06mm-0.1mm and the distance between two adjacent columns of working medium channels being 0.12mm-0.18mm.
3. The micro heat pipe of claim 1, wherein the micro heat pipe is formed on a silicon substrate. The working medium channel has a circular cross-sectional shape, and the diameter of the working medium channel cross-section is 0.02mm-0.05mm.
4. The micro-heat pipe structure according to claim 1, wherein, The sum of the lengths of the insulation section and the condensation section is 2-3 times the length of the evaporation section.
5. The silicon-based structure of a micro heat pipe according to claim 1, characterized in that, Both the insulation section and the condensation section include multiple flow channels. Two adjacent flow channels are arranged in parallel to each other, and branch channels are arranged on both sides of the flow channels. The branch channels are connected to the flow channels at a set angle.
6. The silicon-based structure of a micro heat pipe according to claim 5, characterized in that, The angle between the branch channel and the flow channel is in the range of 20°-60°, and the vertical distance between the end of the branch channel away from the flow channel and the flow channel is 0.05mm-0.07mm.
7. The silicon-based structure of a micro heat pipe according to claim 5, characterized in that, The angle between the branch channel and the flow channel is 40°, and the ratio of the vertical distance between the end of the branch channel away from the flow channel and the flow channel to the distance between two adjacent flow channels is 1 / 3.
8. The silicon-based structure of a micro heat pipe according to claim 1, characterized in that, The thickness of the glass sheet is 0.4mm-0.6mm; The thickness of the silicon-based chip substrate is 0.5mm-0.7mm; The inlet side of the evaporation section is connected to a liquid inlet channel, and there are multiple liquid inlet channels. The outlet side of the condensation section is connected to a liquid outlet channel, and there are multiple liquid outlet channels.
9. A silicon-based structure of a micro heat pipe according to any one of claims 1-8, and a fabrication process for the silicon-based structure of the micro heat pipe, characterized in that, Includes the following: Photolithography on silicon-based chip substrates: using photosensitive materials as an intermediary, the light is transferred to the front side of the silicon-based chip substrate through an illumination pattern; Etching: Etching the liquid wick on the front side of the silicon-based chip substrate. The liquid wick includes a connected evaporation section, an insulation section, and a condensation section. The evaporation section includes multiple working fluid channels, each of which is connected to the insulation section. The multiple working fluid channels are arranged in an array, and adjacent working fluid channels are connected. The silicon-based chip substrate is bonded to a glass sheet to form the original component of the silicon-based micro heat pipe structure.
10. The fabrication process of the silicon-based structure of the micro heat pipe according to claim 9, characterized in that, After the silicon-based chip substrate is bonded to the glass sheet, the following steps are also included: The thickness of the formed original part is measured. If the silicon-based chip substrate is greater than 0.645 mm, the back side of the silicon-based chip substrate is thinned. Polishing and cleaning of silicon-based chip substrates; Silicon dioxide deposition: Depositing a silicon dioxide layer of a predetermined thickness on the back side of a silicon-based chip substrate; Photolithography is performed on the back side of the silicon-based chip substrate; Deposition of Cr and Pt: A Cr layer of a predetermined thickness is deposited on the back side of a silicon-based chip substrate, followed by the deposition of a Pt layer of a predetermined thickness. Peeling: Soak in acetone for a set time, then perform ultrasonic peeling. Secondary photolithography on the back: Secondary photolithography is performed on the back of the silicon-based chip substrate to achieve photolithography of the liquid inlet channel and liquid outlet channel of the silicon-based micro heat pipe structure; Etching: Etching the back side of a silicon-based chip substrate to form a chip.