Thermally conductive layer, method of making a thermally conductive structure, and thermally conductive structure

Abstract

The application provides a heat-conducting layer, comprising: a thermal interface material layer; at least one first single-layer graphene sheet located in the thermal interface material layer, and opposite surfaces of each first single-layer graphene sheet are covered by the thermal interface material layer, and the first single-layer graphene sheet extends in a plane parallel to the thickness direction of the thermal interface material layer. Embodiments of the application provide a heat-conducting layer, a method for manufacturing a heat-conducting structure and the heat-conducting structure, and the heat-conducting efficiency of the heat-conducting layer / heat-conducting structure is increased by arranging the single-layer graphene sheet in the thermal interface material layer.

Description

Technical Field

[0001] The embodiments of the present invention relate to a thermally conductive layer, a method for fabricating a thermally conductive structure, and a thermally conductive structure. Background Technology

[0002] The global high-performance computing (HPC) market is currently growing rapidly, with increasing demand for chip computing power and transmission. As a result, packaging technology is developing towards integrating 3D integrated circuits (ICs) and CPO (Co-Packaged Optics), integrating multiple small chips with different functions into the same package structure. Therefore, heat dissipation of the package structure is gradually becoming a significant issue.

[0003] As the computing power of chips continues to increase, the amount of heat generated also increases. For example, a 2.5D package with a switching capacity of 200 Gb has a data processing power of 1600W; a 2.5D package with a switching capacity of 400 Gb has a data processing power of 3200W; and a 2.5D package with a switching capacity of 800 Gb has a data processing power of 6400W. A 2.5D CPO package with a switching capacity of 1.6 T has a data processing power of 12800W; a 2.5D CPO package with a switching capacity of 3.2 T has a data processing power of 25600W; and a 3D CPO package with a switching capacity of 6.4 T has a data processing power of 51200W. As power increases, the thermal budget also increases accordingly.

[0004] Current thermal interface materials (TIMs) and metals have limited thermal conductivity, and the thermal conductivity (K-value) of currently mass-produced TIMs ranges from 2 W / m×K to 80 W / m×K, which is significantly different from that of metals (e.g., Cu has a thermal conductivity of 400 W / m×K). If the heat load cannot be dissipated in time, cracks will form at the points of thermal stress concentration, affecting wafer performance. Summary of the Invention

[0005] The present invention provides a thermally conductive layer comprising: a thermal interface material layer; at least one first monolayer graphene sheet located in the thermal interface material layer, wherein the opposite sides of each first monolayer graphene sheet are covered by the thermal interface material layer, and the first monolayer graphene sheet extends in a plane parallel to the thickness direction of the thermal interface material layer.

[0006] In some embodiments, the thermal interface material layer has a first surface perpendicular to the thickness direction and a second surface opposite to the first surface, a first monolayer graphene sheet extending from the first surface to the second surface, the first monolayer graphene sheet being exposed on the first surface and the second surface, and being flush with the first surface and the second surface.

[0007] In some embodiments, each pair of adjacent first monolayer graphene sheets are parallel to each other.

[0008] In some embodiments, the ratio of the total volume of at least one first monolayer graphene sheet to the volume of the thermal interface material layer is 1:1.

[0009] In some embodiments, the thermal interface material layer has a first sidewall and a second sidewall that connect the first surface and the second surface together. The first sidewall and the second sidewall are both perpendicular to the first surface and the second surface and are disposed opposite to each other. A first monolayer graphene sheet extends from the first sidewall to the second sidewall. The first monolayer graphene sheet is exposed on the first sidewall and the second sidewall and is flush with the first sidewall and the second sidewall.

[0010] In some embodiments, the thermal interface material layer is divided into a plurality of first thermal interface material layers, and the first thermal interface material layers and first monolayer graphene sheets are alternately arranged such that each first monolayer graphene sheet is sandwiched between two adjacent first thermal interface material layers.

[0011] In some embodiments, the spacing between any two adjacent first monolayer graphene sheets is the same.

[0012] In some embodiments, at least one first monolayer graphene sheet includes a first group of first monolayer graphene sheets and a second group of first monolayer graphene sheets. Each adjacent pair of first monolayer graphene sheets in the first group has a first spacing, and each adjacent pair of first monolayer graphene sheets in the second group has a second spacing. The first spacing is smaller than the second spacing.

[0013] Embodiments of this application also provide a method for fabricating a thermally conductive structure, comprising: providing a carrier; alternately stacking a first thermal interface material layer and a first monolayer graphene sheet on the carrier to obtain a stacked structure, wherein each first monolayer graphene sheet is sandwiched between two adjacent first thermal interface material layers; removing the carrier; and after removing the carrier, cutting the stacked structure through the stacking direction to monolithize the stacked structure and obtain multiple independent stacked units.

[0014] In some embodiments, alternatingly stacking a first thermal interface material layer and a first monolayer graphene sheet includes: after each layer of the first thermal interface material layer is applied, the first thermal interface material layer is cured; after curing, the first monolayer graphene sheet is stacked.

[0015] In some embodiments, the method further includes: arranging a plurality of stacked units laterally spaced apart from each other such that a first monolayer graphene sheet in each stacked unit is arranged longitudinally, wherein the stacking direction is the same as the lateral direction; and providing a plurality of second thermal interface material layers to at least fill the gap between each pair of adjacent stacked units, such that each stacked unit is sandwiched between two adjacent second thermal interface material layers.

[0016] In some embodiments, after filling, a continuously extending second monolayer graphene sheet is formed on a plurality of second thermal interface material layers and a plurality of stacked units to obtain a first thermally conductive unit composed of a plurality of second thermal interface material layers, a plurality of stacked units and a second monolayer graphene sheet; a first metal layer is formed on the second monolayer graphene sheet; after forming the first metal layer, a second thermally conductive unit identical to the first thermally conductive unit is provided; after inverting the second thermally conductive unit, the second monolayer graphene sheet of the second thermally conductive unit is bonded to the first metal layer.

[0017] In some embodiments, the method further includes: after bonding the second monolayer graphene sheet of the second thermally conductive unit to the first metal layer, forming a second metal layer and a third metal layer on the surface of the first thermally conductive unit facing away from the second thermally conductive unit and on the surface of the second thermally conductive unit facing away from the first thermally conductive unit, respectively.

[0018] In some embodiments, the method further includes: after bonding the second monolayer graphene sheet of the second thermally conductive unit to the first metal layer, sequentially stacking a third monolayer graphene sheet and a second metal layer on both the surface of the first thermally conductive unit facing away from the second thermally conductive unit and the surface of the second thermally conductive unit facing away from the first thermally conductive unit. In some embodiments,

[0019] After the second monolayer graphene sheet of the second thermally conductive unit is bonded to the first metal layer, in the longitudinal direction, the multiple second thermal interface material layers in the first thermally conductive unit are aligned one-to-one with the multiple second thermal interface material layers in the second thermally conductive unit. After the second metal layer and the third metal layer are formed, the third metal layer, the second thermally conductive unit, the first metal layer, the first thermally conductive unit, and the second metal layer are longitudinally cut through the second thermal interface material layer to separate the stacked unit in the first thermally conductive unit and the stacked unit in the second thermally conductive unit as a whole.

[0020] Embodiments of this application also provide a thermally conductive structure, including multiple thermally conductive layers and at least one graphene-metal composite layer, wherein the thermally conductive layers and the graphene-metal composite layer are stacked alternately.

[0021] Each thermally conductive layer includes: a thermal interface material layer; at least one first monolayer graphene sheet located in the thermal interface material layer, and the opposite sides of each first monolayer graphene sheet are covered by the thermal interface material layer, and the first monolayer graphene sheet extends in a plane parallel to the stacking direction.

[0022] Each graphene-metal composite layer includes two second monolayer graphene sheets and a first metal layer sandwiched between the two second monolayer graphene sheets.

[0023] In some embodiments, in the stacking direction, the first monolayer graphene sheets of every two adjacent thermally conductive layers are staggered.

[0024] In some embodiments, the first monolayer graphene sheet in each thermally conductive layer is perpendicular to the second monolayer graphene sheet in each graphene-metal composite layer.

[0025] In some embodiments, the first monolayer graphene sheets of every two adjacent thermally conductive layers are aligned in the stacking direction.

[0026] In some embodiments, in every two adjacent thermally conductive layers, the first monolayer graphene sheet of one thermally conductive layer is perpendicular to the first monolayer graphene sheet of the other thermally conductive layer.

[0027] The embodiments of this application increase the thermal conductivity of the thermally conductive layer / structure by setting a single layer of graphene sheet in the thermal interface material layer. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It is worth noting that, according to industry standard practice, the various components are not drawn to scale and are only used for illustrative purposes. In fact, for the sake of clarity of discussion, the dimensions of the various components can be arbitrarily increased or decreased.

[0029] Figure 1 and Figure 2 The packaging structure of the prior art is shown.

[0030] Figure 3 A cross-sectional view of the thermally conductive layer according to an embodiment of this application is shown.

[0031] Figure 4 A perspective view of a thermally conductive layer according to an embodiment of this application is shown.

[0032] Figure 5 A top view of the thermally conductive layer according to an embodiment of this application is shown.

[0033] Figure 6 A first monolayer graphene sheet is shown.

[0034] Figure 7 The graph shows the ratio of the first monolayer graphene sheet to the thermal conductivity of the thermally conductive layer.

[0035] Figure 8A A thermally conductive structure according to some embodiments of this application is shown.

[0036] Figure 8B A top view of two adjacent thermally conductive layers according to an embodiment of this application is shown.

[0037] Figure 9 The first thermal interface material layer is shown coated on the carrier.

[0038] Figure 10 The formation of the first monolayer graphene sheet is shown.

[0039] Figure 11 The first thermal interface material layer is shown coated on the first monolayer graphene sheet.

[0040] Figure 12 The diagram shows the formation of a first monolayer graphene sheet and a first thermal interface material layer on a cured first thermal interface material layer.

[0041] Figure 13 This demonstrates the monolithization of a stacked structure.

[0042] Figure 14 The second thermal interface material layer is shown.

[0043] Figure 15 The first heat-conducting unit is shown.

[0044] Figure 16 The formation of the first metal layer is shown.

[0045] Figure 17 The second heat-conducting unit is shown being bonded to the first metal layer.

[0046] Figure 18 The formation of the second metal layer and the third metal layer is shown.

[0047] Figure 19 It shows the relationship with Figure 18 Different implementations.

[0048] Figure 20 The monolithic thermally conductive structure 300 is shown.

[0049] Figure 21 The packaging structure according to an embodiment of this application is shown.

[0050] Figure 22 The packaging structures according to different embodiments of this application are shown.

[0051] Figure 23 and Figure 24 They respectively showed the same as Figure 22 Different implementations. Detailed Implementation

[0052] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0053] Embodiments of this application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0054] The terms “approximately,” “generally,” “substantial,” “substantial,” “about,” and “approximately” used herein are used to indicate and explain minor variations. For example, when used in conjunction with numerical values, the above terms may refer to a range of variation less than or equal to ±10% of the corresponding numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. As another embodiment, the thickness of a film or layer being “substantially uniform” may refer to the average thickness of the film or layer being less than or equal to ±10% of the standard deviation, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. The term "substantially coplanar" can refer to two surfaces that are within 50 μm along the same plane (such as within 40 μm, 30 μm, 20 μm, 10 μm, or 1 μm along the same plane). If, for example, two components overlap or overlap within 200 μm, 150 μm, 100 μm, 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, or 1 μm, then the two components can be considered "substantially aligned." If the angle between two surfaces or components is, for example, 90° ± 10° (such as ± 5°, ± 4°, ± 3°, ± 2°, ± 1°, ± 0.5°, ± 0.1°, or ± 0.05°), then the two surfaces or components can be considered "substantially perpendicular." When used in conjunction with an event or situation, the terms "approximately," "generally," "substantially," "materially," "about," and "approximately" can refer to the exact occurrence of the event or situation as well as the very close approximation of its occurrence.

[0055] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “backside,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.

[0056] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0057] Figure 1 and Figure 2 The packaging structure of the prior art is shown. Figure 1 In this embodiment, the wafer 510 (material including Si) is connected to the heat sink 530 via a back-side metal layer 520 and a thermal interface material layer 10. Figure 2 In this embodiment, the chip 510 is connected to the lid 540 via the thermal interface material layer 10, and the lid 540 is also connected to the heat sink 530 via the thermal interface material layer 10. Due to the limited thermal conductivity of the thermal interface material layer 10, stress concentration will occur at the corners of the chip 510, resulting in cracks and affecting the performance of the chip 510.

[0058] Figure 3 A cross-sectional view of the thermally conductive layer 100 according to an embodiment of this application is shown. Figure 4 A perspective view of the thermally conductive layer 100 according to an embodiment of this application is shown. Figure 5 A top view of the thermally conductive layer 100 according to an embodiment of this application is shown. Figure 6 A first monolayer graphene sheet 21 is shown. The thermally conductive layer includes a thermal interface material layer 10 and at least one first monolayer graphene sheet 21. At least one first monolayer graphene sheet 21 is located in the thermal interface material layer 10, and opposite sides of each first monolayer graphene sheet 21 are covered by the thermal interface material layer 10. The first monolayer graphene sheet 21 extends in a plane parallel to the thickness direction Z of the thermal interface material layer 10.

[0059] The embodiments of this application increase the thermal conductivity of the thermally conductive layer 100 by providing a first monolayer graphene sheet 21 in the thermal interface material layer 10.

[0060] The first monolayer graphene sheet 21 is a two-dimensional material composed of a single layer of carbon atoms. Within its YZ plane, it exhibits multiple hexagonal network structures, possessing extremely high thermal conductivity. Heat is transferred along the covalent bonds of the hexagonal lattice of carbon atoms, with a thermal conductivity coefficient ranging from 2000 W / m×K to 5000 W / m×K. In the X direction perpendicular to the YZ plane, heat is transferred along the interlayer van der Waals bonds, with a thermal conductivity coefficient ranging from 5 W / m×K to 20 W / m×K.

[0061] The thermal interface material layer 10 covers the first monolayer graphene sheet 21. The thermal interface material layer 10 is not limited to epoxy resin, but can also be silicon-filled material, mixed metal adhesive or other phase change material.

[0062] See Figure 3 The thermal interface material layer 10 has a first surface 101 perpendicular to the thickness direction Z and a second surface 102 opposite to the first surface 101. A first monolayer graphene sheet 21 extends from the first surface 101 to the second surface 102, is exposed on the first surface 101 and the second surface 102, and is flush with the first surface 101 and the second surface 102. The first monolayer graphene sheet 21 penetrates the upper and lower surfaces of the thermal interface material layer 10 along the thickness direction Z, ensuring heat transfer across the entire thickness of the thermal interface material layer 10.

[0063] See Figure 5 The thermal interface material layer 10 has a first sidewall 103 and a second sidewall 104 connecting a first surface 101 and a second surface 102. Both the first sidewall 103 and the second sidewall 104 are perpendicular to the first surface 101 and the second surface 102 and are disposed opposite to each other. A first monolayer graphene sheet 21 extends from the first sidewall 103 to the second sidewall 104, is exposed on the first sidewall 103 and the second sidewall 104, and is flush with the first sidewall 103 and the second sidewall 104. The length of the first monolayer graphene sheet 21 along the Y direction is the same as that of the entire thermal interface material layer 10.

[0064] In some embodiments, the thermal interface material layer 10 is divided into a plurality of first thermal interface material layers 11, and the first thermal interface material layers 11 and the first monolayer graphene sheets 21 are alternately stacked such that each first monolayer graphene sheet 21 is sandwiched between two adjacent first thermal interface material layers 11. In some embodiments, each pair of adjacent first monolayer graphene sheets 21 are parallel to each other.

[0065] In some embodiments, the spacing between any two adjacent first monolayer graphene sheets 21 is the same. That is, the first monolayer graphene sheets 21 are uniformly distributed in the thermal interface material layer 10.

[0066] In other embodiments, the first monolayer graphene sheet 21 can be locally densified in hotter areas. At least one first monolayer graphene sheet 21 includes a first group of first monolayer graphene sheets 21 and a second group of first monolayer graphene sheets 21. Each adjacent pair of first monolayer graphene sheets 21 in the first group has a first spacing, and each adjacent pair of first monolayer graphene sheets 21 in the second group has a second spacing, wherein the first spacing is smaller than the second spacing.

[0067] Figure 7 A graph 700 shows the ratio of the first monolayer graphene sheet 21 to the thermal conductivity of the thermally conductive layer 100. The horizontal axis represents the volume ratio of the first monolayer graphene sheet 21 in the thermally conductive layer 100; the left vertical axis represents the thermal conductivity coefficient of the thermally conductive layer 100, in W / m×K; and the right vertical axis represents the ratio of the thermal conductivity coefficient of the thermally conductive layer 100 to that of the existing thermal interface material layer 10 (which does not contain a monolayer graphene sheet). It can be seen that as the proportion of the first monolayer graphene sheet 21 increases, the thermal conductivity coefficient of the thermally conductive layer 100 also increases. When 50% of the first monolayer graphene sheet 21 is mixed into the thermally conductive layer 100, i.e., the ratio of the total volume of at least one first monolayer graphene sheet 21 to the volume of the thermal interface material layer 10 is 1:1, the thermal conductivity coefficient can reach up to 1040 W / m×K, and the heat dissipation effect is more than 13 times better than that of the existing thermal interface material layer 10.

[0068] In some embodiments, the thermal conductivity coefficient of the thermally conductive layer 100 is calculated according to the following formula: K tot =f×K g +(1−f)×K T , where K tot It is the total thermal conductivity of the thermally conductive layer 100; f is the volume ratio of the first monolayer graphene sheet 21 in the thermally conductive layer 100; K g K is the thermal conductivity of graphene, with a conservative value of approximately 2000 W / m × K; T The thermal conductivity of the thermal interface material layer 10 is taken as 80 W / m×K. The thermal conductivity of the thermally conductive layer 100 in this embodiment is more than twice that of the existing thermal interface material layer 10. Specifically, the thermal conductivity of the thermally conductive layer 100 mixed with 20% of the first monolayer graphene sheet 21 is increased by 5 times, and the thermal conductivity of the thermally conductive layer 100 mixed with 50% of the first monolayer graphene sheet 21 is increased by 13 times.

[0069] Figure 8A A thermally conductive structure 300 according to some embodiments of the present application is shown. The thermally conductive structure 300 includes a plurality of thermally conductive layers 100 and at least one graphene-metal composite layer 40, wherein the thermally conductive layers 100 and the graphene-metal composite layer 40 are stacked alternately.

[0070] Each thermally conductive layer 100 includes a thermal interface material layer 10 and at least one first monolayer graphene sheet 21. The first monolayer graphene sheet 21 is located in the thermal interface material layer 10, and the opposite sides of each first monolayer graphene sheet 21 are covered by the thermal interface material layer 10. The first monolayer graphene sheet 21 extends in the YZ plane parallel to the stacking direction Z.

[0071] Each graphene-metal composite layer 40 includes two second monolayer graphene sheets 22 and a first metal layer 31 sandwiched between the two second monolayer graphene sheets 22.

[0072] Because monolayer graphene sheets are composed of a single layer of carbon atoms, they become increasingly brittle with length along the Z-direction. Furthermore, the thickness of industrial thermal interface materials ranges from approximately 10 μm to 50 μm, and the adhesion between these materials and the monolayer graphene sheets is poor. Therefore, in... Figure 8A In the embodiment shown, the length of the first single-layer graphene sheet 21 in the Z direction is reduced, multiple thermally conductive layers 100 are stacked, and a graphene-metal composite layer 40 is designed to increase the rigidity and thermal conductivity of the thermally conductive structure 300.

[0073] In some embodiments, the first monolayer graphene sheets 21 of every two adjacent thermally conductive layers 100 are aligned in the stacking direction Z. Heat is transferred vertically along the aligned first monolayer graphene sheets 21.

[0074] In other embodiments, the first monolayer graphene sheets 21 of each two adjacent thermally conductive layers 100 can be staggered in the stacking direction. Even if the first monolayer graphene sheets 21 of each two adjacent thermally conductive layers 100 are not aligned, heat can still be conducted laterally through the second monolayer graphene sheets 22 in the graphene-metal composite layer 40, and the heat conduction path will not be broken.

[0075] In some embodiments, the first monolayer graphene sheet 21 in each thermally conductive layer 100 is perpendicular to the second monolayer graphene sheet 22 in each graphene-metal composite layer 40. The second monolayer graphene sheet 22 (extending along the XY plane) and the first monolayer graphene sheet 21 (extending along the YZ plane) are used together to achieve heat conduction in the XYZ directions.

[0076] exist Figure 8AIn the illustrated embodiment, in every two adjacent thermally conductive layers 100, the first monolayer graphene sheet 21 of one thermally conductive layer 100 is parallel to the first monolayer graphene sheet 21 of the other thermally conductive layer 100. In other embodiments, in every two adjacent thermally conductive layers 100, the first monolayer graphene sheet 21 of one thermally conductive layer 100 can be perpendicular to each other. That is, when viewing the thermally conductive structure 300 from above along the stacking direction Z, the upper and lower first monolayer graphene sheets 21 intersect each other, so that the upper and lower first monolayer graphene sheets 21 at least partially overlap in the Z direction, thereby improving thermal conductivity. Figure 8B A top view of two adjacent thermally conductive layers 100 according to an embodiment of this application is shown. It will be understood that the graphene-metal composite layer 40 between the two adjacent thermally conductive layers 100 is omitted to clearly show the positional relationship of the first monolayer graphene sheet 21 in the two adjacent thermally conductive layers 100. Figure 8B In the diagram, the first monolayer graphene sheet 21 in one of the heat-conducting layers 100 is shown by a dashed line. It can be seen that the first monolayer graphene sheets 21 in the two heat-conducting layers 100 are intersected into a mesh, which allows heat to be conducted in the XYZ directions.

[0077] The embodiments of this application also provide a method for manufacturing the thermally conductive layer 100 and the thermally conductive structure 300.

[0078] Figure 9 A carrier 200 is shown, a first thermal interface material layer 11 is coated on the carrier 200, and the first thermal interface material layer 11 is cured. In some embodiments, the thickness of the coated first thermal interface material layer 11 is, for example, 10 μm to 50 μm.

[0079] Figure 10 The diagram illustrates, for example, the formation of a first monolayer graphene sheet 21 on a cured first thermal interface material layer 11 via a chemical vapor deposition (CVD) process.

[0080] Figure 11 The diagram shows the coating of a first thermal interface material layer 11 onto a first monolayer graphene sheet 21 and the curing of the first thermal interface material layer 11.

[0081] Figure 12 The diagram illustrates, for example, the formation of a first monolayer graphene sheet 21 on a cured first thermal interface material layer 11 using a chemical vapor deposition process. The first thermal interface material layer 11 is then coated onto the first monolayer graphene sheet 21, and the first thermal interface material layer 11 is cured.

[0082] Figures 9 to 12The diagram illustrates alternatingly stacking a first thermal interface material layer 11 and a first monolayer graphene sheet 21 on a carrier 200 to obtain a stacked structure 211, wherein each first monolayer graphene sheet 21 is sandwiched between two adjacent first thermal interface material layers 11. Alternatingly stacking the first thermal interface material layer 11 and the first monolayer graphene sheet 21 includes: curing the first thermal interface material layer 11 after each layer is applied; and stacking the first monolayer graphene sheet 21 after curing.

[0083] Figure 13 The diagram shows the removal of the carrier 200. After removing the carrier 200, the stacked structure 211 is cut through along the stacking direction Z to monolithize the stacked structure 211, resulting in multiple independent stacked units 220. After this step, the stacked units 220 can be used as a thermally conductive layer 100. The width of the cut stacked units 220 can be controlled according to the required thickness of the thermally conductive layer 100, so the widths of the multiple stacked units 220 can be the same or different. By cutting the stacked structure 211, the length of the first monolayer graphene sheet 21 in the stacked unit 220 is reduced. The reduced length is, for example, smaller than the coating thickness of the first thermal interface material layer 11 (10 μm to 50 μm), avoiding the first monolayer graphene sheet 21 from becoming too long and brittle.

[0084] Figure 14 The diagram illustrates an arrangement of multiple stacked units 220 spaced apart from each other along a transverse direction X, such that the first monolayer graphene sheets 21 in each stacked unit 220 are arranged longitudinally Z, with the stacking direction being the same as the transverse direction X. Multiple second thermal interface material layers 12 are provided to at least fill the gaps between each pair of adjacent stacked units 220, such that each stacked unit 220 is sandwiched between two adjacent second thermal interface material layers 12. After this step, the resulting structure can be used as a thermally conductive layer 100. The spacing between some of the first monolayer graphene sheets 21 is smaller, for example, the spacing between the first monolayer graphene sheets 21 within each stacked unit 220; while the spacing between some of the first monolayer graphene sheets 21 is larger, for example, the spacing between the first monolayer graphene sheets 21 on both sides of the second thermal interface material layers 12 is larger. The first monolayer graphene sheets 21 can be arranged more densely in regions corresponding to heat sources to specifically provide localized thermal conductivity efficiency.

[0085] Figure 15 It shows in Figure 14 Following the filling step shown, a continuously extending second monolayer graphene sheet 22 is formed on the plurality of second thermal interface material layers 12 and the plurality of stacked units 220 to obtain a first thermally conductive unit 231 composed of the plurality of second thermal interface material layers 12, the plurality of stacked units 220 and the second monolayer graphene sheet 22.

[0086] Figure 16 The diagram illustrates, for example, the formation of a first metal layer 31 on a second monolayer graphene sheet 22 via a physical vapor deposition (PVD) process.

[0087] Figure 17 The diagram illustrates that after the formation of the first metal layer 31, a second heat-conducting unit 232 identical to the first heat-conducting unit 231 is provided. The second heat-conducting unit 232 is inverted, and a second monolayer graphene sheet 22 of the second heat-conducting unit 232 is bonded to the first metal layer 31. After the second monolayer graphene sheet 22 of the second heat-conducting unit 232 is bonded to the first metal layer 31, in the longitudinal direction Z, a plurality of second thermal interface material layers 12 in the first heat-conducting unit 231 are aligned one-to-one with a plurality of second thermal interface material layers 12 in the second heat-conducting unit 232. The two second monolayer graphene sheets 22 and the first metal layer 31 between them form a graphene-metal composite layer 40, constituting a graphene-coated metal sandwich structure. If the heat-conducting structure 300 is likened to a building, the sandwich structure acts as the "floor" / "reinforcing steel" in the heat-conducting structure 300, increasing the mechanical strength of the heat-conducting structure 300. In addition, the adhesion between graphene and metal is good, and the first metal layer 31 can connect the upper and lower second monolayer graphene sheets 22.

[0088] Figure 18 The diagram illustrates that after the second monolayer graphene sheet 22 of the second thermally conductive unit 232 is bonded to the first metal layer 31, a second metal layer 32 and a third metal layer 33 are formed, for example, by physical vapor deposition, on the surface of the first thermally conductive unit 231 facing away from the second thermally conductive unit 232, and on the surface of the second thermally conductive unit 232 facing away from the first thermally conductive unit 231. The second metal layer 32 and the third metal layer 33 serve as back-side metal layers (materials such as Ti / NiV / Au with a thermal conductivity of 40 W / m×K to 50 W / m×K; or Cu with a thermal conductivity of 400 W / m×K) for subsequent press-fitting with the cover 540 / wafer 510 / heat sink 530.

[0089] Figure 19 It shows the relationship with Figure 18 In different embodiments, after the second monolayer graphene sheet 22 of the second heat-conducting unit 232 is bonded to the first metal layer 31, a third monolayer graphene sheet 23 (e.g., by chemical vapor deposition) and a second metal layer 32 (e.g., by physical vapor deposition) are sequentially stacked on both the surface of the first heat-conducting unit 231 facing away from the second heat-conducting unit 232 and the surface of the second heat-conducting unit 232 facing away from the first heat-conducting unit 231. The third monolayer graphene sheet 23 further improves heat dissipation efficiency. Figure 18 and Figure 19After the steps shown, the resulting structures can all be used as heat-conducting structures 300.

[0090] Figure 20 The diagram illustrates that after forming the second metal layer 32 and the third metal layer 33, the third metal layer 33, the second thermally conductive unit 232, the first metal layer 31, the first thermally conductive unit 231, and the second metal layer 32 are longitudinally cut through the second thermal interface material layer 12 in a Z-direction, to separate the stacked unit 220 in the first thermally conductive unit 231 and the stacked unit 220 in the second thermally conductive unit 232 as a whole, resulting in a monolithic thermally conductive structure 300. In some embodiments, the thermally conductive structure 300 is not limited to the two thermally conductive layers 100 shown in the figure, but may include more thermally conductive layers 100 as needed.

[0091] Figure 21 A packaging structure according to an embodiment of this application is shown, wherein a wafer 510 is bonded to a substrate 550 and disposed within a space enclosed by a cover 540 and the substrate 550. A thermally conductive layer 100 connects the wafer 510 and the cover 540, and also connects the cover 540 and the heat sink 530. Because the monolayer graphene sheet has high thermal conductivity in its plane, and the first monolayer graphene sheet 21 extends along a plane parallel to the longitudinal direction Z, heat can be transferred vertically upwards from the wafer 510 along the first monolayer graphene sheet 21 to the cover 540, and then further vertically upwards along the first monolayer graphene sheet 21 to the heat sink 530, thereby achieving a high heat dissipation effect in the vertical direction.

[0092] Figure 22 The illustration shows packaging structures according to different embodiments of this application, wherein thermally conductive structures 300 are used to connect the chip 510 and the cover 540, and between the cover 540 and the heat sink 530. The thermally conductive structure 300 is, for example, a... Figure 18 or Figure 19 The structure shown can also be Figure 20 The monolithic structure is shown. By stacking multiple thermally conductive layers 100, the required thickness of the thermally conductive structure 300 can be met, while avoiding the brittleness caused by an excessively large longitudinal Z length of the first monolayer graphene sheet 21 due to the thickness of the thermally conductive layer 100.

[0093] Figure 23 and Figure 24 They respectively showed the same as Figure 22 Different implementations. In Figure 23 In the illustrated embodiment, the wafer 510 and the cover 540 are connected by a thermally conductive structure 300, and the cover 540 and the heat sink 530 are connected by a thermal interface material layer 10. Figure 24In the illustrated embodiment, the wafer 510 and the cover 540 are connected by a thermal interface material layer 10, and the cover 540 and the heat sink 530 are connected by a thermally conductive structure 300. It is understood that... Figure 21 In the illustrated embodiment, one of the two thermally conductive layers 100 can also be replaced by a thermal interface material layer 10. That is, in the encapsulation structure, the thermally conductive structure 300 / thermally conductive layer 100 is not required at all thermal connection interfaces; it can be selected to use the thermally conductive structure 300 / thermally conductive layer 100 at the interface where the heat load accumulates most in the encapsulation structure. It is understood that... Figure 22 In the embodiment shown, one of the two thermally conductive structures 300 can also be replaced with a thermally conductive layer 100, depending on the actual required thickness.

[0094] The embodiments of this application provide a thermally conductive layer 100 / thermally conductive structure 300 mixed with a single layer of graphene sheet. The embodiments of this application are applicable to all 2.5D / 3D integrated circuit packaging structures and can be used in products such as silicon photonics (SiPh), HPC, mobile devices, and compact universal photonic engines (COUPE). They are not limited by the thickness of the thermally conductive layer 100 / thermally conductive structure 300. The thickness of the thermally conductive layer 100 can be selected according to the required thickness, or multiple layers of thermally conductive layer 100 can be stacked.

[0095] 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 thermally conductive layer, characterized in that, include: Thermal interface material layer; At least one first monolayer graphene sheet is located in the thermal interface material layer, and the opposite sides of each first monolayer graphene sheet are covered by the thermal interface material layer, the first monolayer graphene sheet extending in a plane parallel to the thickness direction of the thermal interface material layer.

2. The thermally conductive layer according to claim 1, characterized in that, The thermal interface material layer has a first surface perpendicular to the thickness direction and a second surface opposite to the first surface. The first monolayer graphene sheet extends from the first surface to the second surface. The first monolayer graphene sheet is exposed on the first surface and the second surface and is flush with the first surface and the second surface.

3. The thermally conductive layer according to claim 2, characterized in that, Each pair of adjacent first monolayer graphene sheets is parallel to each other.

4. The thermally conductive layer according to claim 1, characterized in that, The ratio of the total volume of the at least one first monolayer graphene sheet to the volume of the thermal interface material layer is 1:

1.

5. The thermally conductive layer according to claim 2, characterized in that, The thermal interface material layer has a first sidewall and a second sidewall that connect the first surface and the second surface together. The first sidewall and the second sidewall are both perpendicular to the first surface and the second surface and are disposed opposite to each other. The first monolayer graphene sheet extends from the first sidewall to the second sidewall, the first monolayer graphene sheet is exposed on the first sidewall and the second sidewall, and is flush with the first sidewall and the second sidewall.

6. The thermally conductive layer according to claim 1, characterized in that, The thermal interface material layer is divided into multiple first thermal interface material layers, and the first thermal interface material layers and first monolayer graphene sheets are alternately arranged so that each first monolayer graphene sheet is sandwiched between two adjacent first thermal interface material layers.

7. The thermally conductive layer according to claim 3, characterized in that, The spacing between any two adjacent first monolayer graphene sheets is the same.

8. The thermally conductive layer according to claim 3, characterized in that, The at least one first monolayer graphene sheet includes a first group of first monolayer graphene sheets and a second group of first monolayer graphene sheets. Each adjacent pair of first monolayer graphene sheets in the first group has a first spacing, and each adjacent pair of first monolayer graphene sheets in the second group has a second spacing. The first spacing is smaller than the second spacing.

9. A method for fabricating a thermally conductive structure, characterized in that, include: Provide a carrier; A first thermal interface material layer and a first monolayer graphene sheet are alternately stacked on the carrier to obtain a stacked structure, wherein each first monolayer graphene sheet is sandwiched between two adjacent first thermal interface material layers. Remove the carrier; After removing the carrier, the stacked structure is cut through along the stacking direction to monolithize the stacked structure and obtain multiple independent stacked units.

10. The method according to claim 9, characterized in that, Alternatingly stacking the first thermal interface material layer and the first monolayer graphene sheet includes: After each layer of the first thermal interface material is applied, the first thermal interface material layer is cured. After curing, the first monolayer graphene sheet is stacked.

11. The method according to claim 9, characterized in that, Also includes: The plurality of stacked units are arranged laterally spaced apart from each other, such that the first monolayer graphene sheet in each stacked unit is arranged longitudinally, wherein the stacking direction is the same as the lateral direction; A plurality of second thermal interface material layers are provided to at least fill the gap between each pair of adjacent stacked units, such that each stacked unit is sandwiched between two adjacent second thermal interface material layers.

12. The method according to claim 11, characterized in that, After the filling, a continuously extending second monolayer graphene sheet is formed on the plurality of second thermal interface material layers and the plurality of stacked units to obtain a first thermally conductive unit composed of the plurality of second thermal interface material layers, the plurality of stacked units and the second monolayer graphene sheet. A first metal layer is formed on the second monolayer graphene sheet; After forming the first metal layer, a second heat-conducting unit identical to the first heat-conducting unit is provided. After inverting the second heat-conducting unit, a second monolayer graphene sheet of the second heat-conducting unit is bonded to the first metal layer.

13. The method according to claim 12, characterized in that, Also includes: After the second monolayer graphene sheet of the second thermal conductive unit is bonded to the first metal layer, a second metal layer and a third metal layer are formed on the surface of the first thermal conductive unit opposite to the second thermal conductive unit and on the surface of the second thermal conductive unit opposite to the first thermal conductive unit, respectively.

14. The method according to claim 12, characterized in that, Also includes: After the second monolayer graphene sheet of the second thermal conductive unit is bonded to the first metal layer, a third monolayer graphene sheet and a second metal layer are sequentially stacked on the surface of the first thermal conductive unit facing away from the second thermal conductive unit and on the surface of the second thermal conductive unit facing away from the first thermal conductive unit.

15. The method according to claim 13, characterized in that, After the second monolayer graphene sheet of the second thermally conductive unit is bonded to the first metal layer, in the longitudinal direction, the plurality of second thermal interface material layers in the first thermally conductive unit are aligned one-to-one with the plurality of second thermal interface material layers in the second thermally conductive unit. After the second metal layer and the third metal layer are formed, the third metal layer, the second thermally conductive unit, the first metal layer, the first thermally conductive unit, and the second metal layer are longitudinally cut through at the second thermal interface material layer to separate the stacked unit in the first thermally conductive unit and the stacked unit in the second thermally conductive unit as a whole.

16. A thermally conductive structure, characterized in that, It includes multiple thermally conductive layers and at least one graphene-metal composite layer, wherein the thermally conductive layers and the graphene-metal composite layer are stacked alternately. Each of the thermally conductive layers includes: a thermal interface material layer; at least one first monolayer graphene sheet located in the thermal interface material layer, and the opposite sides of each first monolayer graphene sheet are covered by the thermal interface material layer, and the first monolayer graphene sheet extends in a plane parallel to the stacking direction. Each of the graphene-metal composite layers includes two second monolayer graphene sheets and a first metal layer sandwiched between the two second monolayer graphene sheets.

17. The thermally conductive structure according to claim 16, characterized in that, In the direction of the stacking, the first monolayer graphene sheets of each two adjacent thermally conductive layers are staggered.

18. The thermally conductive structure according to claim 16, characterized in that, The first monolayer graphene sheet in each of the thermally conductive layers is perpendicular to the second monolayer graphene sheet in each of the graphene-metal composite layers.

19. The thermally conductive structure according to claim 16, characterized in that, In the direction of the stack, the first monolayer graphene sheets of every two adjacent thermally conductive layers are aligned.

20. The thermally conductive structure according to claim 16, characterized in that, In each pair of adjacent thermally conductive layers, the first monolayer graphene sheet of one thermally conductive layer is perpendicular to the first monolayer graphene sheet of the other thermally conductive layer.

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