Embedded heat dissipation structure and preparation method thereof

Abstract

The invention provides an embedded heat dissipation structure and a preparation method thereof. The embedded heat dissipation structure comprises a base, a plurality of micron columns and metal liquid, the base comprises a first substrate and a second substrate, and the first substrate and the second substrate define a cavity; the plurality of micron columns are distributed in the cavity of the base at intervals, and one end of at least part of the micron columns is in contact with the first substrate; the metal liquid is located in the cavity and makes contact with the substrate and the micron columns. Due to the fact that the micron columns distributed at intervals are arranged in the cavity, in the flowing process of the metal liquid, the kinematic viscosity of the metal liquid and the substrate is small, then it is guaranteed that the resistance of the metal liquid in the flowing process is small, the speed of the metal liquid is high, and due to the fact that the heat dissipation capacity is in positive correlation with the movement speed of the metal liquid, the heat dissipation efficiency is improved. Therefore, the heat dissipation effect of the embedded heat dissipation structure is good, and the problem that the requirement for efficient heat dissipation is difficult to meet due to an ultra-high-density transistor in a chip in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the semiconductor field, and in particular, to an embedded heat dissipation structure and a preparation method thereof. Background Art

[0002] In recent years, the integration density of transistors in chips has increased rapidly, resulting in an increasingly significant heat accumulation effect caused by leakage current in the gate area of ​​transistors in chips. The working reliability of chips is extremely sensitive to temperature. For every 1°C increase in safe working temperature, its reliability will decrease by about 5%. The heat dissipation path in the integrated circuit chip packaging structure is mainly to diffuse the local high heat generated in the small area of ​​the chip gate area to the substrate through the thermal interface material, and then to the tube shell, and then dissipate the heat into the atmosphere through thermal management technologies such as air cooling and water cooling outside the tube shell.

[0003] However, these traditional thermal management technologies are each limited by shortcomings such as low heat dissipation efficiency and difficulty in structural miniaturization, and are unable to meet the efficient heat dissipation requirements of the new generation of chips.

[0004] Currently, there is also a way of heat dissipation through near-junction. The so-called near-junction heat dissipation is to miniaturize various heat dissipation structures and embed them in the electronic chip packaging structure. The embedded heat dissipation structure is used to bring the liquid cooling medium close to the heating grid area of ​​the electronic chip (the distance is less than 100 microns) to achieve precise control of the junction temperature.

[0005] According to whether the embedded liquid cooling technology requires external energy to drive the cooling medium, it can be divided into two forms: active and passive. Active embedded liquid cooling includes spray cooling, flow boiling, electromagnetic reflux, and steam compression refrigeration. Active embedded liquid cooling requires external non-thermal physical effect power (such as mechanical force, electromagnetic force, etc.) to provide kinetic energy to drive the liquid cooling medium to circulate inside and outside the embedded cavity, but it has disadvantages such as complex structure and limited application scenarios. Passive embedded liquid cooling methods include planar heat pipes, separated heat pipes, and phase change heat storage and heat dissipation. Passive embedded liquid cooling uses the thermal physical effects of liquid cooling medium (such as thermal slip, phase change, capillary condensation, etc.) in a closed cavity to effectively suppress heat accumulation caused by local high heat flux density. However, the physical properties of the materials used in the passive embedded liquid cooling method cannot meet the current microsystem packaging process and operating environment requirements. Summary of the invention

[0006] The main purpose of the present application is to provide an embedded heat dissipation structure and a preparation method thereof to solve the problem in the prior art that the demand for efficient heat dissipation caused by ultra-high density transistors in chips is difficult to meet.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an embedded heat dissipation structure is provided, which includes a base, a plurality of micron-columns and metal liquid, the base includes a first substrate and a second substrate, the first substrate and the second substrate are enclosed to form a cavity; the plurality of micron-columns are distributed in the cavity of the base at intervals, and at least one end of some of the micron-columns is in contact with the first substrate; the metal liquid is located in the cavity, and the metal liquid is in contact with the base and the micron-columns, respectively.

[0008] Optionally, the coverage rate of the micro-columns on the surface of the first substrate is in the range of 6%-14%.

[0009] Optionally, the material of the micron column includes gallium nitride, the material of the substrate includes silicon, and the material of the metal liquid includes gallium.

[0010] Optionally, a cross-sectional shape of the micro-column perpendicular to an extending direction of the micro-column includes a regular quadrilateral.

[0011] Optionally, the distance between two adjacent micro-columns ranges from 12 microns to 17.83 microns, the length of the micro-columns ranges from 8 microns to 12 microns, and the length of the cavity in the extension direction of the micro-columns ranges from 80 microns to 110 microns.

[0012] According to another aspect of the present application, a method for preparing an embedded heat dissipation structure is provided, the method comprising: providing a first substrate and a preliminary substrate; forming a plurality of spaced-apart micrometer columns on the surface of the first substrate; removing a portion of the preliminary substrate to form a first groove, and the remaining preliminary substrate forms a second substrate; bonding the first substrate and the second substrate so that the first groove and the first substrate form a cavity, the micrometer columns are located in the cavity, and the first substrate and the second substrate constitute a base; pouring metal liquid into the cavity, and the metal liquid contacts the base and the micrometer columns, respectively.

[0013] Optionally, forming a plurality of spaced-apart micrometer columns on at least a portion of the surface of the first substrate includes: forming a semiconductor layer on the surface of the first substrate; and removing a portion of the semiconductor layer to form the plurality of spaced-apart micrometer columns.

[0014] Optionally, after bonding the first substrate and the second substrate, the method further comprises: using a chemical mechanical polishing process to process a surface of the first substrate away from the micro-pillars, so that a thickness of the processed first substrate is within a predetermined range.

[0015] Optionally, before pouring the metal liquid into the cavity, the method also includes: removing part of the first substrate and part of the second substrate to form a plurality of second grooves arranged at intervals, the second grooves exposing part of the second substrate; forming a stacked insulating layer, a barrier layer and a metal layer in the second groove to obtain a silicon via, the insulating layer covering the surface of the second groove; removing part of the second substrate to expose the silicon via.

[0016] Optionally, pouring metal liquid into the cavity includes: removing part of the first substrate and part of the micron pillars to form a filling hole, wherein the filling hole exposes the cavity; pouring the metal liquid into the cavity through the filling hole under a predetermined gas atmosphere; and filling the filling hole with an adhesive.

[0017] According to the technical solution of the present application, the embedded heat dissipation structure includes a substrate, a plurality of micron columns and a metal liquid. The substrate includes a first substrate and a second substrate, and the first substrate and the second substrate are enclosed to form a cavity; a plurality of micron columns are spaced apart in the cavity of the substrate, and at least one end of a portion of the micron columns is in contact with the first substrate; the metal liquid is located in the cavity, and the metal liquid is in contact with the substrate and the micron columns, respectively. Compared with the problem that the high-efficiency heat dissipation demand caused by ultra-high density transistors in the chip in the prior art is difficult to meet, the embedded heat dissipation structure of the present application includes the substrate, a plurality of micron columns and the metal liquid, so that the heat dissipation function can be achieved through the flow of the metal liquid, and because there are spaced micron columns in the cavity, the kinematic viscosity of the metal liquid and the substrate is small during the flow of the metal liquid, thereby ensuring that the resistance of the metal liquid during the flow is small, ensuring that the speed of the metal liquid is large, and because the heat dissipation capacity is positively correlated with the movement speed of the metal liquid, the heat dissipation effect of the embedded heat dissipation structure is good, which solves the problem that the high-efficiency heat dissipation demand caused by ultra-high density transistors in the chip in the prior art is difficult to meet. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 A schematic structural diagram of a first substrate and a preliminary substrate according to an embodiment of the present application is shown;

[0020] Figure 2 A schematic diagram of the structure obtained after forming a micron column according to an embodiment of the present application is shown;

[0021] Figure 3 A schematic diagram of a structure obtained after forming a first groove according to an embodiment of the present application is shown;

[0022] Figure 4 A schematic diagram of a structure obtained after bonding a first substrate and a second substrate according to an embodiment of the present application is shown;

[0023] Figure 5 A schematic diagram of a structure obtained after forming a second groove according to an embodiment of the present application is shown;

[0024] Figure 6 A schematic diagram of a structure obtained after forming an insulating layer, a barrier layer and a metal layer according to an embodiment of the present application is shown;

[0025] Figure 7 A schematic diagram of a structure obtained after a portion of the second substrate is removed according to an embodiment of the present application is shown;

[0026] Figure 8 A schematic diagram of a structure obtained after forming a metal connection structure according to an embodiment of the present application is shown;

[0027] Fig. 9 A schematic diagram of the structure obtained after forming a potting port according to an embodiment of the present application is shown;

[0028] Fig.10 A schematic diagram of the structure obtained after pouring metal liquid according to an embodiment of the present application is shown;

[0029] Fig.11 A schematic structural diagram of an embedded heat dissipation structure according to an embodiment of the present application is shown;

[0030] Fig.12 A schematic diagram showing a process of a method for preparing an embedded heat dissipation structure according to an embodiment of the present application is shown;

[0031] Fig.13 A schematic diagram showing the interface surface state of liquid metal at different coverage rates according to an embodiment of the present application is shown;

[0032] Fig.14 A schematic diagram showing the effect of the movement of liquid metal per unit time at different coverage rates according to an embodiment of the present application is shown;

[0033] Fig.15 A schematic diagram showing the relationship between different coverage rates of liquid metal and the logarithm of the resistance ratio according to an embodiment of the present application is shown;

[0034] Fig.16 A structural schematic diagram showing the application of an embedded heat dissipation structure according to an embodiment of the present application;

[0035] Fig.17 A schematic structural diagram of a first substrate and a micro-column according to an embodiment of the present application is shown.

[0036] The above drawings include the following reference numerals:

[0037] 10. Base; 20. Micron column; 30. Metal liquid; 40. First groove; 50. Second groove; 60. Insulation layer; 70. Barrier layer; 80. Metal layer; 90. Filling hole; 100. Adhesive; 101. First substrate; 102. Second substrate; 103. Preparatory substrate; 110. Metal connection structure. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be intermediate elements. Moreover, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element through a third element.

[0041] As introduced in the background technology, the problem that the demand for efficient heat dissipation caused by ultra-high density transistors in chips in the prior art is difficult to meet. To solve the above problem, the embodiments of the present application provide an embedded heat dissipation structure and a preparation method thereof.

[0042] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0043] According to an embodiment of the present application, an embedded heat dissipation structure is provided, such as Fig.11As shown, the above-mentioned embedded heat dissipation structure includes a base 10, a plurality of micron columns 20 and a metal liquid 30, the above-mentioned base 10 includes a first substrate 101 and a second substrate 102, and the above-mentioned first substrate 101 and the above-mentioned second substrate 102 are enclosed to form a cavity; the above-mentioned plurality of micron columns 20 are distributed in the above-mentioned cavity of the above-mentioned base 10 at intervals, and at least one end of the above-mentioned micron columns 20 is in contact with the above-mentioned first substrate 101; the above-mentioned metal liquid 30 is located in the above-mentioned cavity, and the above-mentioned metal liquid 30 is in contact with the above-mentioned base 10 and the above-mentioned micron columns 20 respectively.

[0044] The above-mentioned embedded heat dissipation structure includes a substrate, a plurality of micron columns and a metal liquid. The above-mentioned substrate includes a first substrate and a second substrate, and the first substrate and the second substrate are enclosed to form a cavity; the plurality of micron columns are spaced apart in the cavity of the above-mentioned substrate, and at least one end of the micron columns is in contact with the first substrate; the metal liquid is located in the cavity, and the metal liquid is in contact with the substrate and the micron columns respectively. Compared with the problem that the high-efficiency heat dissipation demand caused by the ultra-high density transistors in the chip in the prior art is difficult to meet, the above-mentioned embedded heat dissipation structure of the present application includes the above-mentioned substrate, the plurality of micron columns and the metal liquid, so that the heat dissipation function can be achieved through the flow of the metal liquid, and because there are spaced micron columns in the cavity, the kinematic viscosity of the metal liquid and the substrate is small during the flow of the metal liquid, thereby ensuring that the resistance of the metal liquid during the flow is small, ensuring that the speed of the metal liquid is large, and because the heat dissipation capacity is positively correlated with the movement speed of the metal liquid, the heat dissipation effect of the above-mentioned embedded heat dissipation structure is good, which solves the problem that the high-efficiency heat dissipation demand caused by the ultra-high density transistors in the chip in the prior art is difficult to meet.

[0045] In the above implementation process, the above-mentioned micron column is modeled after the lotus leaf structure in nature, that is, there is a sparse array composed of a large number of micron-scale synaptic structures on the surface.

[0046] In the specific implementation process, the coverage of the micron column on the surface of the first substrate is in the range of 6%-14%. Since the coverage of the micron column on the surface of the first substrate is in the range of 6%-14%, within this range, the dynamic viscosity of the liquid metal can be significantly reduced, thereby enhancing the fluidity of the liquid metal to improve the overall heat dissipation performance, further ensuring that the heat dissipation effect of the embedded heat dissipation structure is better.

[0047] In the above implementation process, the coverage of the above micro-columns on the surface of the above first substrate is preferably 8.5%. Of course, in the actual application process, the above micro-columns with different coverages can also be prepared, and the optimal coverage can be obtained through experimental testing.

[0048] In order to further ensure that the embedded heat dissipation structure has a good heat dissipation effect, the material of the micron column includes gallium nitride, the material of the substrate includes silicon, and the material of the metal liquid includes gallium. Since the material of the micron column includes gallium nitride, and the material of the metal liquid includes gallium, that is, the liquid gallium is used as the flowing metal, gallium has high thermal conductivity (50.75W / (m·K)), high boiling point (2403℃), low melting point (15.5℃), low thermal expansion coefficient (<7.5×10 -5 PPM%@-65-350℃), diamagnetic(-21.6×10 -6 cm 3 / mol@290K) and other excellent physical and chemical properties, further ensuring that the above-mentioned embedded heat dissipation structure has a good heat dissipation effect.

[0049] In the above implementation process, the heat dissipation performance of the embedded heat dissipation structure is mainly affected by the properties of the heat transfer medium itself and its speed in the embedded cavity. The power source of the heat transfer medium in the passive heat dissipation structure in the embedded cavity is mainly the Marangoni effect, that is, the temperature difference on the solid surface will cause the liquid metal to have a surface tension difference, thereby driving the liquid metal to flow. However, if the above-mentioned micron column is not set, the high kinematic viscosity of the above-mentioned liquid metal gallium on the silicon interface hinders the increase of its speed, thereby weakening the overall heat dissipation capacity, resulting in the current liquid metal planar heat pipe passive heat dissipation structure generally having low heat dissipation efficiency. The present application reduces the resistance of the above-mentioned liquid metal gallium during movement by setting the above-mentioned micron column, further ensuring that the heat dissipation effect of the above-mentioned embedded heat dissipation structure is better.

[0050] In the prior art, there are two main types of heat dissipation fluids used in planar heat pipe passive embedded liquid cooling solutions. One type uses common low-boiling point, low-viscosity substances such as water, ethanol, FC770, etc. as embedded liquid cooling fluids. Although the relevant fluids have the advantages of low price and mature properties, their physical properties cannot fully meet the process compatibility tests in actual engineering processes such as microsystem packaging process (200-400℃), operating environment (-65-150℃), and rework process (100-200℃). Gallium is selected as the liquid metal in this application because gallium has high thermal conductivity (50.75W / (m·K)), high boiling point (2403℃), low melting point (15.5℃), and low thermal expansion coefficient (<7.5×10 -5 PPM%@-65-350℃), diamagnetic(-21.6×10 - 6 cm 3 / mol@290K) and other excellent physical and chemical properties ensure that the above-mentioned liquid metal in this application can meet the process compatibility test in the actual engineering process.

[0051] In a specific implementation process, the cross-sectional shape of the micro-column along the direction perpendicular to the extension direction includes a regular quadrilateral.

[0052] In the above implementation process, the above-mentioned micron column is a regular quadrangular prism.

[0053] Of course, the cross-sectional shape of the above-mentioned micro-columns along the direction perpendicular to the extension direction is not limited to a regular quadrilateral. In actual application, the above-mentioned micro-columns with different cross-sectional shapes can also be prepared, and then the cross-sectional shape with the best heat dissipation capacity can be determined through actual tests and / or theoretical tests.

[0054] In a specific embodiment, the distance between two adjacent micron columns ranges from 12 microns to 17.83 microns, the length of the micron columns ranges from 8 microns to 12 microns, and the length of the cavity in the extension direction of the micron columns ranges from 80 microns to 110 microns.

[0055] In the above implementation process, the side length of the regular quadrilateral corresponding to the above micron column is preferably 2 microns, and the length of the above micron column is preferably 10 microns.

[0056] Of course, the distance between the above-mentioned micron columns, the length of the above-mentioned micron columns and the length of the above-mentioned cavity in the extension direction of the micron columns are not limited to the above ranges. In actual application, structures of different lengths can also be prepared, and then the length, distance and height of the micron columns with optimal heat dissipation capacity can be determined through actual tests and / or theoretical tests, wherein the height of the above-mentioned cavity needs to be greater than the length of the above-mentioned micron columns.

[0057] According to an embodiment of the present application, a method for preparing an embedded heat dissipation structure is provided.

[0058] Fig.12 FIG. 1 is a flow chart of a method for preparing an embedded heat dissipation structure according to an embodiment of the present application. Fig.12 As shown, the method comprises the following steps:

[0059] Step S1201, as Figure 1 As shown, a first substrate 101 and a preliminary substrate 103 are provided;

[0060] Specifically, the materials of the first substrate and the preliminary substrate both include silicon. The first substrate and the preliminary substrate need to be double-sided polished silicon wafers, and then undergo standard organic cleaning, acetone ultrasonic cleaning, isopropanol ultrasonic cleaning, deionized water ultrasonic cleaning, and nitrogen drying processes.

[0061] Step S1202, as Figure 2 As shown, a plurality of micrometer columns 20 distributed at intervals are formed on the surface of the first substrate 101;

[0062] Specifically, the coverage rate of the micro-rods on the surface of the first substrate is in the range of 6%-14%, preferably 8.5%, and the material of the micro-rods includes gallium nitride.

[0063] Step S1203, as Figures 1 to 3 As shown, a portion of the above-mentioned prepared substrate 103 is removed to form a first trench 40, and the remaining above-mentioned prepared substrate 103 forms a second substrate 102;

[0064] Specifically, by removing part of the above-mentioned preliminary substrate, not only the above-mentioned first groove is formed, but also a plurality of silicon pillars spaced apart are formed in the groove. The subsequent formation of the above-mentioned second groove is formed by removing part of the silicon pillars in the above-mentioned second substrate, that is, the above-mentioned insulating layer, the above-mentioned barrier layer and the above-mentioned metal layer are all located in the above-mentioned second groove in the silicon pillar, wherein the thickness of the above-mentioned preliminary substrate includes 350 microns, the above-mentioned first groove is formed by deep reactive ion etching, and the depth of the above-mentioned first groove includes 100 microns. Of course, the specific thickness is not limited and is determined according to actual conditions.

[0065] Step S1204, as Figures 2 to 4 As shown, the first substrate 101 and the second substrate 102 are bonded so that the first groove 40 and the first substrate 101 form a cavity, the micro-pillar 20 is located in the cavity, and the first substrate 101 and the second substrate 102 constitute a base 10;

[0066] Specifically, by bonding the first substrate and the second substrate, the silicon pillars in the second substrate are in contact with the first substrate, that is, a plurality of silicon pillars are spaced apart from each other at the bottom of the first substrate and the second substrate.

[0067] Step S1205 , pouring metal liquid into the cavity, wherein the metal liquid contacts the substrate and the micron column respectively.

[0068] Specifically, the above-mentioned metal liquid includes gallium.

[0069] In the preparation method of the above-mentioned embedded heat dissipation structure, first, a first substrate and a preliminary substrate are provided; then, a plurality of spaced-apart micrometer columns are formed on the surface of the above-mentioned first substrate; then, a portion of the above-mentioned preliminary substrate is removed to form a first groove, and the remaining above-mentioned preliminary substrate forms a second substrate; then, the above-mentioned first substrate and the above-mentioned second substrate are bonded so that the above-mentioned first groove and the above-mentioned first substrate form a cavity, the above-mentioned micrometer column is located in the above-mentioned cavity, and the above-mentioned first substrate and the above-mentioned second substrate constitute a base; finally, metal liquid is poured into the above-mentioned cavity, and the above-mentioned metal liquid contacts the above-mentioned base and the above-mentioned micrometer column respectively. Compared with the problem that the demand for efficient heat dissipation caused by ultra-high density transistors in chips in the prior art is difficult to meet, the preparation method of the above-mentioned embedded heat dissipation structure of the present application first forms the above-mentioned first substrate and the multiple spaced-apart micron columns on the surface of part of the above-mentioned first substrate, then forms the above-mentioned second substrate with grooves, and forms a cavity by bonding, and the micron columns are located in the cavity, and finally metal liquid is poured into the cavity, so that the heat dissipation function can be achieved through the flow of the above-mentioned metal liquid. Since there are spaced-apart micron columns in the cavity, the kinematic viscosity of the above-mentioned metal liquid and the above-mentioned substrate is small during the flow of the above-mentioned metal liquid, thereby ensuring that the resistance of the above-mentioned metal liquid during the flow is small, ensuring that the speed of the above-mentioned metal liquid is large, and since the heat dissipation capacity is positively correlated with the movement speed of the above-mentioned metal liquid, the heat dissipation effect of the above-mentioned embedded heat dissipation structure is better, which solves the problem that the demand for efficient heat dissipation caused by ultra-high density transistors in chips in the prior art is difficult to meet.

[0070] In order to further ensure that the above-mentioned embedded heat dissipation structure has a better heat dissipation effect, a plurality of spaced-apart micro-pillars are formed on at least part of the surface of the above-mentioned first substrate, including: forming a semiconductor layer on the surface of the above-mentioned first substrate; removing part of the above-mentioned semiconductor layer to form the above-mentioned plurality of spaced-apart micro-pillars. By forming the above-mentioned semiconductor layer on the surface of the above-mentioned first substrate, and then removing part of the above-mentioned semiconductor layer, the remaining above-mentioned semiconductor layer forms the above-mentioned plurality of spaced-apart micro-pillars, that is, by controlling the coverage of the above-mentioned micro-pillars on the surface of the above-mentioned first substrate, the resistance of the above-mentioned liquid metal in the flow process is minimized, thereby further ensuring that the above-mentioned embedded heat dissipation structure has a better heat dissipation effect.

[0071] In the above implementation process, the semiconductor layer is formed by molecular beam epitaxy and chemical vapor substrate, and the thickness of the semiconductor layer includes 10 microns. Of course, the specific thickness is not limited and is determined according to the actual situation. The removal of part of the semiconductor layer is formed by processing a graphic design photomask arranged with gallium nitride columns. First, photoresist is spin-coated, and then, a photolithography machine is used for photolithography to form a heterogeneous graphic interface to obtain a plurality of spaced micron columns. In addition, a plurality of micron columns can be formed outside the first substrate, which can be determined according to the actual situation.

[0072] In a specific embodiment, after bonding the first substrate and the second substrate, the method further comprises: using a chemical mechanical polishing process to process the surface of the first substrate away from the micro-pillars, so that the thickness of the processed first substrate is within a predetermined range. A portion of the first substrate is removed by a chemical mechanical masking process, so that the remaining thickness of the first substrate is small, ensuring that the remaining first substrate meets the thickness requirements for subsequent formation of TSV (Through Silicon Via).

[0073] In the above implementation process, the thickness of the above first substrate after chemical mechanical masking is 50 microns. Of course, the specific thickness is not limited and is determined according to actual conditions.

[0074] In a specific implementation process, before the metal liquid is poured into the cavity, the method further includes: Figure 4 as well as Figure 5 As shown, a portion of the first substrate 101 and a portion of the second substrate 102 are removed to form a plurality of second grooves 50 arranged at intervals, wherein the second grooves 50 expose a portion of the second substrate 102; Figures 5 and 6 As shown, a stacked insulating layer 60, a barrier layer 70 and a metal layer 80 are formed in the second trench 50 to obtain a through silicon via, and the insulating layer 60 covers the surface of the second trench 50; Figure 6 to Figure 7As shown, a part of the second substrate 102 is removed, and the remaining thickness of the second substrate 102 is about 150 microns. Of course, the specific thickness is not limited and is determined according to actual conditions, so that the silicon through hole is exposed. By removing a part of the first substrate and a part of the second substrate, that is, by removing a part of the first substrate and a part of the silicon pillars in the middle of the second substrate, a plurality of the second grooves arranged at intervals are formed, and the second grooves expose part of the silicon pillars. Then, by forming the stacked insulating layer, the barrier layer and the metal layer in the second grooves, the metal layer and the silicon in the second substrate can be isolated by the insulating layer, so as to prevent the DC leakage of the metal layer and reduce the static consumption. The barrier layer can further prevent the metal in the metal layer from entering the second substrate. At the same time, the barrier layer can also improve the adhesion between the metal layer and the insulating layer. Then, the connection is achieved through the metal layer, which ensures that the embedded heat dissipation structure can be connected with other structures.

[0075] Of course, the above embedded heat dissipation structure is not limited to being applied to TSV, but can also be applied to other structures.

[0076] In the above implementation process, the material of the insulating layer includes silicon dioxide, the material of the barrier layer includes titanium or titanium nitride, and the material of the metal layer includes copper. Of course, the materials of the insulating layer, the barrier layer, and the metal layer can also be selected from other materials with the same performance according to actual conditions.

[0077] In addition, after removing part of the second substrate and before pouring the metal liquid into the cavity, the method further comprises: Figures 7 and 8 As shown, a metal connection structure 110 is formed, and the metal connection structure 110 is located at both ends of the through silicon via, and the metal connection structure 110 covers a portion of the surface of the first substrate 101 and the second substrate 102, that is, an RDL (Re Distribution Layer) process.

[0078] In order to further ensure that the above-mentioned embedded heat dissipation structure has a better heat dissipation effect, metal liquid is poured into the above-mentioned cavity, including: Figures 8 to 9 As shown, a portion of the first substrate 101 and a portion of the micro-pillars 20 are removed to form a sealing hole 90, and the sealing hole 90 exposes the cavity; as shown in FIG. Figures 9 and 10 As shown, in a predetermined gas atmosphere, including nitrogen, of course, other gases can also be selected, the above-mentioned metal liquid 30 is poured into the above-mentioned cavity through the above-mentioned filling hole 90; Figure 10 to Figure 11As shown, the bonding material 100 is filled in the above-mentioned encapsulation hole 90. The above-mentioned encapsulation hole is formed by removing part of the above-mentioned first substrate and part of the above-mentioned micro-pillars, so that the above-mentioned metal liquid can be poured into the above-mentioned cavity through the above-mentioned encapsulation hole, and the process of pouring is carried out under the above-mentioned predetermined gas atmosphere, so that the above-mentioned predetermined gas exists between the above-mentioned metal liquid and the above-mentioned substrate, further ensuring that the resistance to the flow of the above-mentioned metal liquid is small, and further ensuring that the heat dissipation effect of the above-mentioned embedded heat dissipation structure is good.

[0079] In the above implementation process, the adhesive includes a high-temperature ceramic adhesive to ensure a firm connection between the liquid metal and the TSV adapter plate. Subsequently, the ceramic adhesive is completely cured by curing at a curing temperature of 200 degrees Celsius to ensure a stable connection and packaging effect. Specifically, since the cavities around the TSV are connected, the metal liquid can be poured into the entire cavity through one of the above-mentioned potting holes. Therefore, the number of the above-mentioned potting holes can be one or more, which is determined according to actual conditions.

[0080] In addition, the above-mentioned embedded heat dissipation structure of the present application will not only expose the nanoscale silicon surface, but also confine part of the nitrogen used to fill the planar heat pipe in the structural gap, which can ensure that the above-mentioned liquid metal obtains sufficient thermal energy from the highly wettable surface of the above-mentioned micron column, while maintaining the drag reduction performance of the low wettability gap, thereby achieving an excellent heterogeneous interface super-wetting thermal sliding effect. In addition, the preparation process of the above-mentioned embedded heat dissipation structure is mature and simple, easy to integrate into the existing micro-nano processing technology, and has a large range of applications.

[0081] Example

[0082] The following will be combined Figures 13 to 16 The process of confirming the optimal coverage of the liquid metal is described below.

[0083] Fig.13 To illustrate the schematic diagram of the liquid state on the interface surface, Figure (a) and Figure (b) show the contact between the droplet and the interface under uniform wetting and non-uniform wetting, respectively. From the figure, we can intuitively see that under non-uniform wetting, the contact area between the droplet and the interface is smaller. It can be inferred that the sliding resistance of the droplet is lower at this time, which provides a direction for further calculations. Fig.14 Based on the multi-body dissipative particle dynamics model, the motion effect diagram of a droplet with a certain initial velocity per unit time under different roughness (i.e. the proportion of GaN columns to the total area) obtained by LAMMPS (Large-scale Atomic Molecular Massively Parallel Simulator). From top to bottom, the proportion of GaN columns to the total area is 0%, 2.5%, 8.5%, and 100%, respectively. Fig.14 It can be seen that when the proportion of GaN columns to the total area is 8.5%, the droplet moves the farthest, which further indicates that the slip resistance of the interface is the smallest; Fig.15 Based on the multi-body dissipative particle dynamics model, the GaN column coverage and the logarithm of the resistance ratio of the gallium droplet at the heterogeneous interface and the silicon interface under different roughness (i.e., the proportion of the GaN column to the total area) obtained by LAMMPS are shown in the broken line relationship. If the vertical axis is greater than 0, it means that under this coverage, the sliding resistance is greater than the sliding resistance of the pure silicon interface, and vice versa. Therefore, from the figure, we can conclude that the optimal range of the GaN column coverage is 6%-14%. Fig.16 The schematic diagram of the structure of the adapter board in which the above-mentioned embedded heat dissipation structure is applied to the chip is shown.

[0084] First, in order to better explain the principle of how the present invention achieves drag reduction gain, we first need to know that on the nanostructured surface, the wettability of the droplet may present one of two states: uniform wetting or non-uniform wetting. Fig.13 As shown in FIG. 1 , when the metal liquid is Ga, the micron column is GaN, and the first substrate is Si, the structural relationship among the metal liquid Ga, the micron column GaN, and the first substrate Si is shown in FIG. Fig.13 In (a), the liquid Ga completely penetrates the nanostructure, while for non-uniform wetting, such as Fig.13 In (b), there is gas (nitrogen) trapped in the gap between the surface and the droplet Ga. These two states are called the Wenzel state and the Cassie state. The contact angle of the droplet in the Wenzel state can be given by the Wenzel equation: cosθ W =rcosθ Y ,θ Y is the Young's contact angle of the liquid drop Ga on a smooth surface, and r is the roughness ratio, which is the ratio of the real area of ​​the solid surface to its projected area. From the Wenzel equation, it can be seen that if the surface is non-wetting (θ Y >90°), the roughness (r>1) will make the contact angle θ W Greater than Young's contact angle θ Y If the surface is wetted (θ Y <90°), roughness (r>1) will make the contact angle θ W Smaller than Young's contact angle θ Y For a droplet in the Cassie state, the contact angle is given by the Cassie-Baxter equation: cosθ CB =r f cosθ Y +f-1#(3-10), where f is the wetted portion of the projected area, r fis the roughness ratio of the wetted area;

[0085] Then, if Fig.14 As shown, when the metal liquid is Ga, the micron column is GaN and the first substrate is Si, in order to further explore the effect of interface roughness on the sliding resistance of the droplet and find the optimal proportion of the heterogeneous interface to the total area, that is, to determine the optimal value of the coverage of the micron column GaN on the first substrate so that the movement distance of the metal liquid Ga is the farthest, we simulated the metal liquid gallium droplet sliding on the first substrate silicon and the micron column gallium nitride layer with different surface roughness nanostructures through the mesoscopic MDPD (Multi-particle Dissipative Particle Dynamics) model, and compared the sliding resistance of the micron column gallium nitride layer with different roughness nanostructures to the metal liquid gallium droplet. The simulation results are shown in the figure below. Fig.14 as well as Fig.15 shown. Fig.14 (a) shows the case where the above-mentioned micron column GaN is not provided. In addition, when the coverage of the above-mentioned micron column GaN in the epitaxial nanostructure is less than 2.5%, as shown in FIG. Fig.14 (b) shows the sliding state of the above-mentioned metal liquid gallium droplet on the surface of the nanostructure micron column gallium nitride coverage density of 2.25%). The above-mentioned metal liquid gallium droplet is in the Wenzel state at the low roughness solid-liquid interface. In this state, the above-mentioned metal liquid gallium droplet has a large contact area with the silicon surface and cannot obtain the sliding drag reduction effect; when the epitaxial nanostructure micron column gallium nitride coverage density is higher than 2.5%, the above-mentioned metal liquid gallium droplet solid-liquid interface sliding state is the Cassie state. When the nanostructure micron column gallium nitride coverage density is between 6% and 14%, as shown in FIG. Fig.14 (c) shows the sliding state of the above-mentioned metal liquid gallium droplet on the surface with 8.5% nanostructure micron column gallium nitride coverage density, which is in the super-immersion slip region, and its sliding resistance can be reduced to 20% of the silicon surface; when the epitaxial nanostructure micron column gallium nitride coverage density is higher, its interface is close to the pure gallium nitride surface, and the high wettability of the above-mentioned micron column gallium nitride to the above-mentioned metal liquid gallium causes its sliding resistance to be 3.5 times greater than that of the silicon surface. Fig.14 (d) If Fig.14 It can be seen from (a), (b), (c) and (d) that the distance of the metal liquid corresponding to (c) which covers 8.5% is the farthest, that is, the resistance is the smallest. Therefore, the coverage rate of the micro-columns on the first substrate is selected to be the optimal 8.5%;

[0086] Afterwards, if Fig.15As shown, when the metal liquid is Ga, the micron column is GaN and the first substrate is Si, the ordinate In order to further verify the validity of the micro-mesoscopic simulation results from a macroscopic perspective, we obtained the slip resistance of the nanostructured gallium nitride heterointerface under the non-uniform wetting Cassie state through the mesoscopic superwetting MDPD model simulation, which can be converted into the kinematic viscosity coefficient of the gallium droplet when sliding on a medium-roughness silicon substrate. Furthermore, in the constructed macroscopic heterointerface superwetting thermal slip FEM model, when the gallium droplet is in a 20℃ / mm thermal gradient environment, its thermal slip steady-state velocities on the gallium nitride, silicon and medium-roughness nanostructured gallium nitride surfaces are 0.008m / s, 0.15m / s and 1.8m / s, respectively. In summary, when the proportion of the gallium nitride heterointerface to the total area is 6%-14%, it can effectively reduce the slip resistance of the liquid metal on the interface, increase its maximum speed driven by the Marangoni effect, and thus enhance the overall heat transfer capacity;

[0087] Finally, the schematic diagram of the heterogeneous interface applied to the passive heat dissipation structure is shown in Fig.16 As shown, a high-performance CPU chip embedded cavity adapter board is taken as an example. Fig.16 The middle left picture is a schematic diagram of the structure of the heterogeneous interface in the embedded liquid cooling structure, including the TSV part, the CPU chip, the RAM chip, the first substrate 101 and the multiple micron pillars 20, wherein the enlarged view of the first substrate 101 and the multiple micron pillars 20 is shown in the right figure. The area consists of two parts: the silicon substrate (the first substrate 101) and the gallium nitride pillar array (the multiple micron pillars 20). In the schematic diagram, the gallium nitride pillar array occupies 8.5% of the total area of ​​the silicon substrate.

[0088] in addition, Fig.17 A schematic diagram of the structure of the first substrate and the plurality of micrometer columns is shown, as shown in Fig.17 It can be seen that the plurality of micro-pillars 20 are arranged in an array on the surface of the first substrate 101. Of course, the plurality of micro-pillars are not limited to being arranged in an array, and are determined according to actual conditions. The distance between any two adjacent micro-pillars may be different, and the shapes of different micro-pillars may also be different.

[0089] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0090] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0091] 1) The embedded heat dissipation structure of the present application includes a substrate, a plurality of micron columns and metal liquid, wherein the substrate includes a first substrate and a second substrate, and the first substrate and the second substrate are enclosed to form a cavity; the plurality of micron columns are distributed in the cavity of the substrate at intervals, and at least one end of some of the micron columns is in contact with the first substrate; the metal liquid is located in the cavity, and the metal liquid is in contact with the substrate and the micron columns, respectively. Compared with the problem that the demand for efficient heat dissipation caused by ultra-high density transistors in the chip in the prior art is difficult to meet, the above-mentioned embedded heat dissipation structure of the present application includes the above-mentioned substrate, the multiple above-mentioned micron columns and the above-mentioned metal liquid, so that the heat dissipation function can be achieved through the flow of metal liquid. Moreover, since there are spaced micron columns in the cavity, the kinematic viscosity of the above-mentioned metal liquid and the above-mentioned substrate is small during the flow of the above-mentioned metal liquid, thereby ensuring that the resistance of the above-mentioned metal liquid during the flow is small, ensuring that the speed of the above-mentioned metal liquid is large, and since the heat dissipation capacity is positively correlated with the movement speed of the above-mentioned metal liquid, the heat dissipation effect of the above-mentioned embedded heat dissipation structure is good, which solves the problem that the demand for efficient heat dissipation caused by ultra-high density transistors in the chip in the prior art is difficult to meet.

[0092] 2) In the preparation method of the above-mentioned embedded heat dissipation structure of the present application, first, a first substrate and a preliminary substrate are provided; then, a plurality of spaced-apart micrometer columns are formed on the surface of the above-mentioned first substrate; then, a portion of the above-mentioned preliminary substrate is removed to form a first groove, and the remaining above-mentioned preliminary substrate forms a second substrate; then, the above-mentioned first substrate and the above-mentioned second substrate are bonded so that the above-mentioned first groove and the above-mentioned first substrate form a cavity, the above-mentioned micrometer column is located in the above-mentioned cavity, and the above-mentioned first substrate and the above-mentioned second substrate constitute a base; finally, metal liquid is poured into the above-mentioned cavity, and the above-mentioned metal liquid is in contact with the above-mentioned base and the above-mentioned micrometer column, respectively. Compared with the problem that the demand for efficient heat dissipation caused by ultra-high density transistors in chips in the prior art is difficult to meet, the preparation method of the above-mentioned embedded heat dissipation structure of the present application first forms the above-mentioned first substrate and the multiple spaced-apart micron columns on the surface of part of the above-mentioned first substrate, then forms the above-mentioned second substrate with grooves, and forms a cavity by bonding, and the micron columns are located in the cavity, and finally metal liquid is poured into the cavity, so that the heat dissipation function can be achieved through the flow of the above-mentioned metal liquid. Since there are spaced-apart micron columns in the cavity, the kinematic viscosity of the above-mentioned metal liquid and the above-mentioned substrate is small during the flow of the above-mentioned metal liquid, thereby ensuring that the resistance of the above-mentioned metal liquid during the flow is small, ensuring that the speed of the above-mentioned metal liquid is large, and since the heat dissipation capacity is positively correlated with the movement speed of the above-mentioned metal liquid, the heat dissipation effect of the above-mentioned embedded heat dissipation structure is better, which solves the problem that the demand for efficient heat dissipation caused by ultra-high density transistors in chips in the prior art is difficult to meet.

[0093] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An embedded heat dissipation structure, characterized in that: The embedded heat dissipation structure comprises: A substrate, comprising a first substrate and a second substrate, wherein the first substrate and the second substrate enclose a cavity; A plurality of micrometer pillars are spaced apart and distributed in the cavity of the base, and at least one end of a portion of the micrometer pillars is in contact with the first substrate; The metal liquid is located in the cavity, and the metal liquid is in contact with the substrate and the micron column respectively.

2. The embedded heat dissipation structure according to claim 1, characterized in that: The coverage rate of the micro-pillars on the surface of the first substrate is in the range of 6%-14%.

3. The embedded heat dissipation structure according to claim 1, characterized in that: The material of the micron column includes gallium nitride, the material of the substrate includes silicon, and the material of the metal liquid includes gallium.

4. The embedded heat dissipation structure according to claim 1, characterized in that: A cross-sectional shape of the micro-column perpendicular to an extending direction of the micro-column includes a regular quadrilateral.

5. The embedded heat dissipation structure according to claim 1, characterized in that: The distance between two adjacent micro-pillars ranges from 12 microns to 17.83 microns, the length of the micro-pillars ranges from 8 microns to 12 microns, and the length of the cavity in the extension direction of the micro-pillars ranges from 80 microns to 110 microns.

6. A method for preparing an embedded heat dissipation structure, characterized in that: The method comprises: providing a first substrate and a preliminary substrate; forming a plurality of spaced-apart micrometer columns on at least a portion of the surface of the first substrate; removing a portion of the prepared substrate to form a first trench, and forming the remaining prepared substrate into a second substrate; Bonding the first substrate and the second substrate so that the first groove and the first substrate form a cavity, the micro-column is located in the cavity, and the first substrate and the second substrate constitute a base; Metal liquid is poured into the cavity, and the metal liquid is in contact with the substrate and the micron column respectively.

7. The method according to claim 6, characterized in that Forming a plurality of spaced-apart micrometer columns on at least a portion of the surface of the first substrate, comprising: forming a semiconductor layer on a surface of the first substrate; A portion of the semiconductor layer is removed to form a plurality of the micrometer columns distributed at intervals.

8. The method according to claim 6, characterized in that After bonding the first substrate and the second substrate, the method further includes: A surface of the first substrate away from the micro-pillars is processed by a chemical mechanical polishing process, so that a thickness of the processed first substrate is within a predetermined range.

9. The method according to claim 6, characterized in that Before pouring the metal liquid into the cavity, the method further comprises: removing a portion of the first substrate and a portion of the second substrate to form a plurality of second grooves arranged at intervals, wherein the second grooves expose a portion of the second substrate; forming a stacked insulating layer, a barrier layer and a metal layer in the second trench to obtain a through silicon via, wherein the insulating layer covers a surface of the second trench; A portion of the second substrate is removed to expose the through silicon via.

10. The method according to claim 6, characterized in that Filling the cavity with liquid metal, comprising: Removing part of the first substrate and part of the micro-pillars to form a potting hole, wherein the potting hole exposes the cavity; In a predetermined gas atmosphere, pouring the metal liquid into the cavity through the potting hole; The potting holes are filled with adhesive.

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