Integrated circuit structure and forming method thereof

Abstract

One aspect of the present disclosure relates to an integrated circuit (IC) structure. The IC structure includes a die and an integrated heat spreader structure disposed over the die. In some embodiments, the integrated heat sink structure includes a first closed-loop microchannel structure adjacent to the die and a second closed-loop microchannel structure disposed over the first closed-loop microchannel structure. In an example, the second closed-loop microchannel structure is disposed farther away from the die than the first closed-loop microchannel structure. In some embodiments, the plurality of microchannels and the micromixer chamber collectively provide a first closed-loop microchannel structure and a second closed-loop microchannel structure. The embodiment of the invention also relates to a method for forming the integrated circuit structure.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to integrated circuit structures and methods of forming the same. Background Art

[0002] The electronics industry has a growing demand for smaller and faster electronic devices that can simultaneously support more and more complex and sophisticated functions. In order to meet these demands, there is a continuing trend in the integrated circuit (IC) industry to manufacture low-cost, high-performance and low-power ICs. So far, these goals have been achieved to a large extent by reducing the size of the IC (e.g., the minimum IC component size), thereby improving production efficiency and reducing related costs. However, this scaling down also increases the complexity of the IC manufacturing process. Therefore, achieving continued progress in IC devices and their performance requires similar progress in IC manufacturing processes and technologies.

[0003] In particular, while shrinking IC dimensions continue to improve device performance, increasing device density also increases power density, which in turn makes IC thermal management a key challenge for semiconductor technology development. In some examples, advanced IC devices can generate high heat fluxes with localized hot spots that degrade device performance and reliability. Although various solutions have been explored to provide cooling for high-performance devices, their heat exchange efficiency has been limited to date.

[0004] Therefore, the prior art is not entirely satisfactory in all respects. Summary of the invention

[0005] An embodiment of the present disclosure provides an integrated circuit structure, comprising: an integrated circuit die; and an integrated heat sink structure, arranged above the integrated circuit die; wherein the integrated heat sink structure comprises a first closed-loop microchannel structure adjacent to the integrated circuit die and a second closed-loop microchannel structure arranged above the first closed-loop microchannel structure, the second closed-loop microchannel structure being arranged to be farther away from the integrated circuit die than the first closed-loop microchannel structure; and wherein a plurality of microchannels and micromixer chambers jointly provide the first closed-loop microchannel structure and the second closed-loop microchannel structure.

[0006] Another embodiment of the present disclosure provides an integrated circuit (IC) structure, comprising: a tube core; and an integrated heat sink, arranged above the tube core, the integrated heat sink comprising a plurality of closed-loop microchannel structures and a first micromixer chamber; wherein the plurality of closed-loop microchannel structures are coupled to the first micromixer chamber through a first corresponding inlet fluid; wherein the plurality of closed-loop microchannel structures are coupled to the first micromixer chamber through a first common outlet fluid; and wherein each of the first corresponding inlets comprises a pump, the pump being configured to control the liquid injected into the first micromixer chamber via the first corresponding inlet.

[0007] Yet another embodiment of the present disclosure provides a method of forming an integrated circuit structure, comprising: providing an integrated heat sink above a die, wherein the integrated heat sink comprises a first closed-loop microchannel structure fluidically coupled to a micromixer chamber via a first inlet and a second closed-loop microchannel structure fluidically coupled to the micromixer chamber via a second inlet, and wherein a first pump is coupled to the first inlet and a second pump is coupled to the second inlet; injecting a liquid into the micromixer chamber via the first inlet at a first speed; and injecting the liquid into the micromixer chamber via the second inlet at a second speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, in accordance with standard practice in the industry, the various components are not drawn to scale and are for illustrative purposes only. In fact, the dimensions of the various components may be arbitrarily increased or reduced for clarity of discussion. It should also be emphasized that the accompanying drawings illustrate only typical embodiments of the present disclosure and, therefore, should not be considered limiting in scope, as the present disclosure may be equally well applied to other embodiments. In addition, the drawings may implicitly describe features that are not explicitly described in the detailed description.

[0009] Figure 1 A cross-sectional view of an IC structure including an integrated heat sink (IHS) structure is shown in accordance with some embodiments.

[0010] Figure 2A and Figure 2B An exemplary velocity-time graph is shown showing control pulses corresponding to liquid injected through each of the first and second inlets of an IHS structure, according to some embodiments.

[0011] Figure 3 An exemplary electro-fluid dynamic (EHD) pump is shown in accordance with some embodiments.

[0012] Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 and Fig.10 Cross-sectional views of IC structures including various alternative designs of IHS structures are shown according to some embodiments.

[0013] Fig.11 An integrated circuit (IC) cooling assembly including an IHS structure is shown in accordance with some embodiments.

[0014] Fig.11A According to some embodiments Fig.11 Top view of the IC cooling assembly.

[0015] Fig. 12A and Fig. 12B According to some embodiments Fig.11 A portion of an IC cooling assembly is also shown, and additional components of the IC cooling assembly are also shown.

[0016] Fig.13 A flow chart is shown of a method of cooling an IC die using an IHS structure according to some embodiments. DETAILED DESCRIPTION

[0017] The following disclosure provides many different embodiments or examples for implementing the different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, forming a first component above or on a second component may include an embodiment in which the first component and the second component are directly contacted, and may also include an embodiment in which an additional component may be formed between the first component and the second component so that the first component and the second component may not be in direct contact. In addition, the present disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0018] For ease of description, spatially relative terms such as "below," "beneath," "lower," "above," "upper," and the like may be used herein to describe the relationship of one element or component to another element or component as shown in the figures. Spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation shown in the figures. The device may be positioned in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein may likewise be interpreted accordingly. It should also be noted that in the following discussion, the terms "liquid" and "fluid" are sometimes used interchangeably, and the use of such terms is not meant to be limiting in any way. In addition, although the various embodiments disclosed herein are primarily discussed with reference to liquids (e.g., such as water or magnetic fluids), in at least some embodiments, the liquids or fluids referred to herein may include one or more gases.

[0019] In addition, when "about", "approximately", etc. are used to describe a numerical value or a range of values, the term is intended to cover values ​​within a reasonable range, taking into account the inherent variations during manufacturing as understood by those of ordinary skill in the art. For example, based on the known manufacturing tolerances associated with manufacturing components having characteristics associated with the numerical value, the numerical value or range of values ​​covers a reasonable range including the described numerical value, such as within + / -10% of the described numerical value. For example, a material layer with a thickness of "about 5nm" can cover a size range from 4.25nm to 5.75nm, where the manufacturing tolerance associated with the deposited material layer is known to those of ordinary skill in the art to be + / -15%. In addition, the disclosed dimensions of different components may implicitly disclose the dimensional ratios between the different components. In addition, the present disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0020] In order to meet the continuous demand for the release of advanced integrated circuit (IC) devices and circuits, IC size (e.g., minimum IC component size) is continuously scaled down. The reduction in IC size improves device performance and increases device density. However, the increased device density also increases power density, which in turn leads to IC thermal management becoming a key challenge for the development of semiconductor technology. In some examples, advanced IC devices can generate high heat fluxes with local hot spots, which will reduce device performance and reliability. As a potential solution, some existing embodiments use embedded microchannels as part of an integrated heat sink (IHS) (e.g., arranged on a die or die package) as an effective method to improve the heat exchange efficiency of the HIS. For example, a single closed-loop microchannel can be used as part of the IHS. However, as the length of the microchannel increases and the complexity increases, such a microchannel will experience high flow resistance and therefore have limited heat exchange efficiency. In order to overcome the high flow resistance, more power may be required to drive the liquid coolant through the microchannel. Therefore, the length and / or design of the microchannel are limited. Although single closed-loop microchannels embedded as part of the IHS and other solutions have been explored to provide cooling for advanced and high-performance IC devices, overall, their heat exchange efficiency is limited. Therefore, the prior art is not entirely satisfactory in all respects.

[0021] Embodiments of the present disclosure provide advantages over the prior art, but it should be understood that other embodiments may provide different advantages, not all advantages need to be discussed herein, and no particular advantage is required by all embodiments. For example, embodiments discussed herein include integrated heat sink structures and related methods that support thermal cooling of IC dies and packages and are effectively used to overcome various shortcomings of existing methods. In some embodiments, an integrated heat sink (IHS) structure includes a plurality of closed-loop microchannels coupled to a hybrid active-passive micro-mixer chamber to improve the heat exchange efficiency of the IHS structure for use in high-performance computing packaging products.

[0022] In various examples, the IHS structure is disposed on a die or die package, wherein a thermal interface material (TIM) layer is disposed between the IHS structure and the die or die package. In some cases, the IHS structure may include a first microchannel adjacent to the die or die package and a second microchannel disposed above the first microchannel, the second microchannel being further away from the die or die package than the first microchannel. In various embodiments, the micromixer chamber is coupled to the first microchannel and the second microchannel via corresponding inlet and outlet fluids. In some embodiments, the first microchannel and the second microchannel may provide two closed-loop microchannels together with the micromixer chamber to improve heat exchange efficiency.

[0023] The inlets of the first microchannel and the second microchannel can be coupled to a pump, which can be controlled using active oscillation input phase (OIP) control. In various embodiments, the OIP control provides control of the liquid injected into the micromixer chamber (e.g., by controlling the liquid velocity and phase (in time)). Generally, active OIP control can be used to adjust and / or improve the heat exchange efficiency. For example, OIP control of the liquid injected into the inlet can control the corresponding amount and / or corresponding speed of the injected liquid (of various temperatures) injected into the micromixer chamber via the corresponding microchannel to further improve the heat exchange efficiency of the IHS structure.

[0024] According to various embodiments, the micromixer chamber and the microchannel inlet can have various designs, each design can provide different heat exchange efficiencies to accommodate different heat sinks, different tube cores or different tube core packages. In some embodiments, the liquid used as a coolant in the IHS structure can include water and / or a magnetic fluid, as described in more detail below. Regardless of the specific design of the IHS structure, embodiments of the present disclosure provide improved thermal cooling of IC tube cores and packages, thereby directly addressing the IC thermal management challenges associated with advanced IC circuits and devices. Additional details of embodiments of the present disclosure are provided below, and additional benefits and / or other advantages will become apparent to those skilled in the art who benefit from the present disclosure.

[0025] Figure 1 A cross-sectional view of a semiconductor or IC structure 100 including a substrate 102, a die 104, and an integrated heat sink (IHS) structure 110 is shown. The die 104 may include logic devices (including high-power devices, such as high-power logic devices), memory devices, and / or devices including other functions. The IC structure 100 may be an IC package mounted on a printed circuit board (PCB). In other embodiments, the substrate 102 may include a PCB, a packaging substrate, a semiconductor substrate, an interposer, a dielectric substrate, and / or other supporting components. In some embodiments, the substrate 102 may include conductive traces connected to the die 104 above. In some embodiments, the substrate 102 may include input / output terminals, such as bumps, balls, or columns (e.g., for providing an electrical connection to the PCB below). In addition, in some examples, the die 104 may include input / output terminals, such as bumps, balls, or columns, for providing an electrical connection to the substrate 102 below (e.g., using a flip chip process).

[0026] In some embodiments, an intervening thermal interface material (TIM) layer 108 is used to couple the IHS structure 110 to the die 104 to enhance heat transfer therebetween. The TIM layer 108 may include a variety of different types of materials, such as thermal gel, thermal paste, graphite, diamond, silver, aluminum nitride, boron nitride, aluminum oxide, silicon nitride, silicon carbide, ceramics, metals, and / or other thermally conductive materials or combinations thereof. In some embodiments, such as those described below with reference to Fig.11 As mentioned above, the external heat sink may be disposed above the IHS structure 110 and attached to the IHS structure 110 through another TIM layer.

[0027] In various embodiments, the IHS structure 110 includes a plurality of microchannels 112 and a micro-mixer chamber 116, which together provide a first closed-loop microchannel structure 114A and a second closed-loop microchannel structure 114B, through which a liquid coolant is configured to flow. In the example, the first closed-loop microchannel structure 114A and the second closed-loop microchannel structure 114B are fluidly coupled to the micro-mixer chamber 116 via a first inlet 118 and a second inlet 120, respectively. In addition, the first closed-loop microchannel structure 114A and the second closed-loop microchannel structure 114B are fluidly coupled to the micro-mixer chamber 116 via an outlet 122. Therefore, in this example, the micro-mixer chamber 116 has two inlets 118, 120 and a single (or common) outlet 122.

[0028] In some examples, the micro-mixer chamber 116 has a substantially square or rectangular shape (in a cross-sectional view), as shown, having a first side S1, a second side S2 opposite and parallel to the first side S1, a third side S3, and a fourth side S4 opposite and parallel to the third side S3. The first side S1 and the second side S2 are also perpendicular to the third side S3 and the fourth side S4. However, it will be understood that the shape of the micro-mixer chamber 116 is not limited to the examples shown, and in some embodiments, the micro-mixer chamber 116 may have other shapes in a cross-sectional view, such as a circle, an oval, an ellipse, a triangle, a trapezoid, a hexagon, a pentagon, other polygonal shapes, and other shapes in a three-dimensional view, such as a cube, a sphere, a cuboid, a cone, a cylinder, a pyramid, a prism, or other suitable shapes. In the example shown, the first inlet 118 and the second inlet 120 are both fluidly coupled to the same side (first side S1) of the micro-mixer chamber 116, and the first inlet 118 and the second inlet 120 are parallel to each other and oriented perpendicularly to a plane defined by the first side S1 of the micro-mixer chamber 116. As shown, the outlet 122 is fluidly coupled to a central portion of a second side S2 of the micro-mixer chamber 116 opposite the first side S1, and the outlet 122 is oriented perpendicularly to a plane defined by the second side S2 of the micro-mixer chamber 116.

[0029] In the illustrated embodiment, the first closed-loop microchannel structure 114A is disposed adjacent to (e.g., closer to) the tube core 104 below, while the second closed-loop microchannel structure 114B is disposed above the first closed-loop microchannel structure 114A. Therefore, the second closed-loop microchannel structure 114B is further away from the tube core 104 than the first closed-loop microchannel structure 114A. In some embodiments, the ratio of the width of the micromixer chamber 116 and the microchannel 112 may be in the range between about 5:1 to about 15:1. In some cases, the width of the microchannel 112 at each of the first inlet 118 and the second inlet 120 may be the same or different. In some embodiments, the ratio of the width and length of the micromixer chamber 116 may be in the range between about 1:1 to about 1:5. If the micromixer chamber 116 is too thin (or too narrow), the heat exchange efficiency of the IHS structure 110 may be worse.

[0030] In various embodiments, the IHS structure 110 further includes a first pump 124 linearly coupled to the microchannel 112 of the first closed-loop microchannel structure 114A, and a second pump 126 linearly coupled to the microchannel 122 of the second closed-loop microchannel structure 114B. In other words, the first pump 124 is coupled to the first inlet 118 of the first closed-loop microchannel structure 114A, and the second pump 126 is coupled to the second inlet 120 of the second closed-loop microchannel structure 114B. In some embodiments, the first pump 124 is used to control the liquid injected into the micromixer chamber 116 via the first inlet 118, and the second pump 126 is used to control the liquid injected into the micromixer chamber 116 via the second inlet 120. In some examples, the liquid is injected into the micromixer chamber 116 via each of the first inlet 118 and the second inlet 120 at different times. However, in at least some cases, the liquid can be injected into the micromixer chamber 116 via each of the first inlet 118 and the second inlet 120 at the same time or at partially overlapping times. As described in more detail below, each of the first pump 124 and the second pump 126 is coupled to and controlled using a controller such as an active oscillation input phase (OIP) controller, which can provide control of the rate, amount, and phase of liquid injected into the micromixer chamber 116 via corresponding ones of the first inlet 118 and the second inlet 120.

[0031] During operation, the heat 125A generated by the die 104 will primarily come from the device layer 104A of the die 104, in which heat generating devices (e.g., such as transistors for providing logic devices including high-power devices, memory devices, and / or other devices) are disposed. The heat 125A generated by the die 104 can be transferred upward (e.g., by conduction) to the IHS structure 110 through the die 104. The IHS structure 110 then transfers the heat 125B away from the IHS structure 110 (e.g., by convection). More specifically, when the liquid travels through the microchannels 112 of the first closed-loop microchannel structure 114A adjacent to the die 104, the liquid flowing through the first closed-loop microchannel structure 114A can receive the transfer of most of the heat 125A from the die 104. Therefore, the liquid entering the micromixer chamber 116 via the first inlet 118 can be hotter than the liquid entering the micromixer chamber 116 via the second inlet 120. Thus, the first inlet 118 may be referred to as a hot inlet, and the second inlet 120 may be referred to as a cold inlet. In some embodiments, the temperature of the liquid at the first inlet 118 (hot inlet) may be in the range between about 80-100 degrees Celsius, the temperature of the liquid at the second inlet 120 (cold inlet) may be in the range between about 25-40 degrees Celsius, and thus the temperature difference between the first inlet 118 and the second inlet 120 (hot inlet and cold inlet) may be in the range between about 40-75 degrees Celsius. The micro-mixer chamber 116 including the hot inlet and the cold inlet (the first inlet 118 and the second inlet 120) provides mixing of the hot liquid / cold liquid entering the hot inlet / cold inlet, resulting in enhanced heat exchange at the outlet 122. In some embodiments, the temperature difference between the first inlet 118 (hot inlet) and the outlet 122 may be in the range between about 15-30 degrees Celsius. The liquid flowing out of the outlet 122 will be split at the microchannel junction 112A, wherein a first portion of the liquid passes through the first closed-loop microchannel structure 114A and a second portion of the liquid passes through the second closed-loop microchannel structure 114B. In some cases, as the liquid travels adjacent to the top surface of the IHS structure 110, heat 125B can be substantially transferred away from the IHS structure 110 via the microchannels 112 of the second closed-loop microchannel structure 114B, thereby ensuring that the liquid entering the micromixer chamber 116 via the second inlet 120 remains cooler than the liquid entering the micromixer chamber 116 via the first inlet 118.

[0032] Returning to the OIP controller for controlling the first pump 124 and the second pump 126, and referring to Figure 2A and Figure 2B , which shows exemplary velocity-time graphs 200, 210 showing control pulses corresponding to liquid injected through each of the first inlet 118 and the second inlet 120. Figure 2AIn the graph 200 of FIG. 1 , and as indicated by the control pulses for each of the first inlet 118 and the second inlet 120, the liquid is injected through each of the first inlet 118 and the second inlet 120 at substantially the same speed (V1), while being phase-shifted (in time) from one another, such that at any given time, only one of the first inlet 118 and the second inlet 120 is injecting liquid into the micromixer chamber 116. In some optional embodiments, the liquid may be injected into the micromixer chamber 116 through each of the first inlet 118 and the second inlet 120 at the same time (e.g., the control pulses in the graph 200 for the inlets 118, 120 completely overlap or are in phase with one another) or at partially overlapping times (e.g., the control pulses in the graph 200 for the inlets 118 and 120 partially overlap or are partially phase-shifted in time). Figure 2B In the graph 210 of FIG. 2 , liquid is injected through each of the first inlet 118 and the second inlet 120 according to different pairs of control pulses having matching speeds, while being phase-shifted (in time) from each other, such that at any given time, only one of the first inlet 118 and the second inlet 120 injects liquid into the micromixer chamber 116. For example, as shown in the graph 210 and as shown by the control pulses for each of the first inlet 118 and the second inlet 120, for each of the first inlet 118 and the second inlet 120, liquid may be injected through each of the first inlet 118 and the second inlet 120 in sequence (one after the other) at the same first speed (V2). Thereafter, for each of the first inlet 118 and the second inlet 120, liquid may be injected through each of the first inlet 118 and the second inlet 120 in sequence at the same second speed (V3), wherein the second speed is different from the first speed. Although some examples of controlling the first pump 124 and the second pump 126 using an OIP controller (e.g., via control pulses corresponding to liquid injected via each of the first inlet 118 and the second inlet 120) have been given, it will be understood that other embodiments are equally possible. For example, in some cases, liquid injected via the first inlet 118 may generally have a different velocity than liquid injected via the second inlet 120. In other cases, different amounts of liquid may be injected via each of the first inlet 118 and the second inlet 120 (e.g., as currently shown, control pulses corresponding to each inlet 118, 120 may have different widths as opposed to substantially similar widths and similar amounts of injected liquid). Providing control of the first pump 124 and the second pump 126 through an OIP controller, and therefore controlling liquid injected into the micro-mixer chamber 116 via each of the first inlet 118 and the second inlet 120, will improve the heat exchange efficiency of the IHS structure 110.

[0033] As discussed above, the IHS structure 110 includes a first pump 124 coupled to the first inlet 118 and a second pump 126 coupled to the second inlet 120. In some embodiments, the first pump 124 and the second pump 126 can be implemented using internal pumps or external pumps, such as electromechanical (e.g., MEMS-based) pumps, electric pumps (EK pumps), or micro pumps. In some embodiments, the first pump 124 and the second pump 126 can be implemented using electro-fluid dynamic (EHD) pumps to drive the liquid through the microchannel 112 and into the respective inlets of the first inlet 118 and the second inlet 120. Reference Figure 3 , wherein an exemplary EHD pump 300 is shown. In some embodiments, the EHD pump 300 is implemented within a portion of the microchannel 112. Thus, in some cases, the geometry (e.g., length 'L', width 'W', and height 'H') of the EHD pump 300 can be substantially the same as the geometry of the microchannel 112. Of course, in some cases, the EHD pump 300 can have a different geometry than the microchannel 112 to which it is linearly coupled (e.g., where at least one of the length, depth, and width is different between the EHD pump 300 and the linearly coupled microchannel 112).

[0034] As shown, the EHD pump 300 includes an emitter 302 and a collector 304, between which a voltage is applied. The flow rate and pressure of the liquid 308 flowing through the EHD pump 300 (e.g., including the speed, amount, and phase of the liquid 308) can be controlled by the applied voltage (e.g., the flow rate and pressure increase as the voltage increases). In some examples, the body of the EHD pump 300 (which may include a portion of the microchannel 112) may include silicon, glass, or other semiconductor materials or dielectric materials. Therefore, in some embodiments, the IHS structure 110 itself may be composed of silicon, glass, another semiconductor material or dielectric material, or a combination thereof. In an example, the emitter 302 and the collector 304 may include copper, silver, gold, tungsten, nickel, aluminum, or other suitable conductive materials. In some optional embodiments where the EHD pump 300 is not embedded in the IHS structure 110, such as when an external pump is used, the IHS structure 110 may be composed of copper or other highly thermally conductive materials. To be sure, in some cases, IHS structure 110 may be composed of copper and still include embedded EHD pump 300 , such as by providing a protective insulating layer around EHD pump 300 , isolating EHD pump 300 (and emitter 302 and collector 304 ) from surrounding copper structures.

[0035] In some embodiments, the liquid 308 used as a coolant in the IHS structure 110 and thus in the EHD pump 300 may include water, a magnetic fluid, a dielectric fluid, or other suitable fluid. In some cases, if the microchannel 112 is very thin or narrow, such as making one or more of the length 'L', width 'W', and height 'H' of the microchannel 112 less than about 100 microns, the liquid used in the microchannel 112 may be polarized and exhibit magnetism even when the coolant used is not a magnetic fluid. For example, water used as a coolant in a microchannel 112 having a size less than about 100 microns may be polarized and exhibit magnetism. As a result, the EHD pump (e.g., implemented as one or both of the first pump 124 and the second pump 126) may drive the polarized liquid through the microchannel 112 in response to an applied voltage. In an optional embodiment, the coolant used in the IHS structure 110 may be a magnetic fluid. As an example, such a magnetic fluid may include iron oxide (Fe3O4), which may be suspended in one or more organic solvents. By using such a magnetic fluid or magnetic nanoparticles suspended in an organic solvent, in some cases, the size of the microchannel 112 can be greater than 100 microns, wherein the magnetic fluid is still strongly polarized and can be driven by an EHD pump (e.g., implemented as one or both of the first pump 124 and the second pump 126). In some embodiments, a suitable surfactant can be added to cover the magnetic nanoparticles. In various cases, the use of a microchannel 112 with a larger size and the corresponding use of a magnetic fluid can provide enhanced heat exchange efficiency and can be easier to manufacture.

[0036] Reference now Figures 4 to 10 , which shows something like Figure 1 1 is a cross-sectional view of a semiconductor or IC structure 100 of a semiconductor or IC structure, but provides exemplary optional designs of an IHS structure 110. Specifically, various designs of the IHS structure 110 may include various designs of multiple microchannels 112, micromixer chambers 116, closed-loop microchannel structures, and / or inlets and outlets of the micromixer chambers 16, wherein each of the various designs may provide different heat exchange efficiencies to accommodate different heat sinks, different dies, or different die packages. Therefore, in some cases, the various designs shown and described herein may be used to accommodate different types of heat generating devices that generate different amounts of heat.

[0037] Figure 4A cross-sectional view of a semiconductor or IC structure 400 is shown, which includes a substrate 102, a die 104, and an integrated heat sink (IHS) structure 410 coupled to the die 104 using a TIM layer 108. The substrate 102, the die 104, and the TIM layer 108 can be substantially the same as discussed above. Like the IHS structure 110, the IHS structure 410 includes a plurality of microchannels 112 and a micromixer chamber 116 (having an exemplary square or rectangular shape as discussed above), which together provide a first closed-loop microchannel structure 114A and a second closed-loop microchannel structure 114B, through which a liquid coolant is configured to flow. However, compared to the IHS structure 110, the configuration of the IHS structure 410 provides different positions and orientations of the first inlet 118 and the second inlet 120 and the outlet 122 relative to the micromixer chamber 116, thereby providing a different heat exchange efficiency than the IHS structure 110. For example, in the IHS structure 410, the first inlet 118 is fluidly coupled to the top of the first side S1 of the micromixer chamber 116 adjacent to the first vertex VX1 of the micromixer chamber 116, and the second inlet 120 is fluidly coupled to a lateral portion of the fourth side S4 of the micromixer chamber 116 adjacent to the first side S1 and the first vertex VX1. The first inlet 118 and the second inlet 120 are also oriented perpendicular to each other and perpendicular to the respective planes defined by the first side S1 and the fourth side S4 of the micromixer chamber 116. As shown, the outlet 122 is fluidly coupled to the bottom of the second side S2 of the micromixer chamber 116 (opposite to the first side S1) and adjacent to the second vertex VX2 diagonally opposite to the first vertex VX1, and the outlet 122 is oriented perpendicular to the plane defined by the second side S2 of the micromixer chamber 116.

[0038] In the example of the IHS structure 410, as with the IHS structure 110, the first closed-loop microchannel structure 114A is disposed adjacent to (e.g., closer to) the underlying die 104, while the second closed-loop microchannel structure 114B is disposed above the first closed-loop microchannel structure 114A. Thus, the second closed-loop microchannel structure 114B is further away from the die 104 than the first closed-loop microchannel structure 114A. In various embodiments, the IHS structure 410 (as with the IHS structure 110) includes a first pump 124 coupled to the first inlet 118 and a second pump 126 coupled to the second inlet 120 to control the liquid injected into the micromixer chamber 116 via respective ones of the first inlet 118 and the second inlet 120.

[0039] During operation of the IHS structure 410, when liquid travels through the microchannels 112 of the first closed-loop microchannel structure 114A adjacent to the wick 104, the heat 125A generated by the wick 104 will be primarily transferred to the liquid flowing through the first closed-loop microchannel structure 114A. Therefore, the liquid entering the micromixer chamber 116 via the first inlet 118 (hot inlet) may be hotter than the liquid entering the micromixer chamber 116 via the second inlet 120 (cold inlet). The micromixer chamber 116 including the hot inlet and the cold inlet (the first inlet 118 and the second inlet 120) provides mixing of hot liquid / cold liquid entering the hot inlet / cold inlet, resulting in enhanced heat exchange at the outlet 122. In particular, in the IHS structure 410, the relative distances between the inlets 118, 120, and the outlet 122 are greater than the distances between the inlets 118, 122, and the outlet 122 in the IHS structure 110. As a result, heat exchange between hot liquid and cold liquid within the micro-mixer chamber 116 can be more efficient for the IHS structure 410 than for the IHS structure 110. The liquid flowing out of the outlet 122 will be split at the microchannel junction 112A, with a first portion of the liquid passing through the first closed-loop microchannel structure 114A and a second portion of the liquid passing through the second closed-loop microchannel structure 114B. In this example, as the liquid travels adjacent to the top surface of the IHS structure 410, heat 125B can be largely transferred away from the IHS structure 410 via the microchannels 112 of the second closed-loop microchannel structure 114B, thereby ensuring that the liquid entering the micro-mixer chamber 116 via the second inlet 120 remains cooler than the liquid entering the micro-mixer chamber 116 via the first inlet 118.

[0040] Figure 5A cross-sectional view of a semiconductor or IC structure 500 is shown, which includes a substrate 102, a die 104, and an integrated heat sink (IHS) structure 510 coupled to the die 104 using a TIM layer 108. The substrate 102, the die 104, and the TIM layer 108 can be substantially the same as discussed above. Like the IHS structure 110, the IHS structure 510 includes a plurality of microchannels 112, but also includes a plurality of micromixer chambers 116A, 116B (as discussed above, having exemplary square or rectangular shapes), which together provide a first closed-loop microchannel structure 114A, a second closed-loop microchannel structure 114B, and a third closed-loop microchannel structure 114C, through which a liquid coolant is configured to flow. In addition to the plurality of micromixer chambers 116A, 116B, the configuration of the IHS structure 510 provides different positions and orientations of various inlets (entering respective micromixer chambers of the plurality of micromixer chambers 116A, 116B) and outlets (exiting respective micromixer chambers of the plurality of micromixer chambers 116A and 116B), thereby providing different heat exchange efficiencies from the IHS structure 110. For example, in the IHS structure 510, the first inlet 118 is fluidly coupled to the top of the first side S1 of the first micromixer chamber 116A adjacent to the first vertex VX1 of the first micromixer chamber 116A, and the second inlet 120 is fluidly coupled to a lateral portion of the fourth side S4 of the first micromixer chamber 116A adjacent to the first side S1 and the first vertex VX1 of the first micromixer chamber 116A. The first inlet 118 and the second inlet 120 are also oriented perpendicularly to each other and perpendicularly to respective planes defined by the first side S1 and the fourth side S4 of the first micromixer chamber 116A. As shown, the outlet 122A of the first micromixer chamber 116A is fluidly coupled to the bottom of the second side S2 of the first micromixer chamber 116A (opposite to the first side S1), and is adjacent to the second vertex VX2 diagonally opposite to the first vertex VX1, and the outlet 122A is oriented perpendicular to the plane defined by the second side S2 of the first micromixer chamber 116A. Then, the outlet 122A of the first micromixer chamber 116A is fluidly coupled to the second micromixer chamber 116B as a first inlet. In particular, the outlet 122A is fluidly coupled to the bottom of the first side S1 of the second micromixer chamber 116B adjacent to the third vertex VX3 of the second micromixer chamber 116B, and the third inlet 121 is fluidly coupled to the lateral portion of the third side S3 of the second micromixer chamber 116B adjacent to the first side S1 and the second vertex VX2 of the second micromixer chamber 116B. The outlet 122A (being the inlet of the second micromixer chamber 116B) and the third inlet 121 are oriented perpendicularly to each other and to respective planes defined by the first side S1 and the third side S3 of the second micromixer chamber 116B.As shown, the outlet 122B of the second micromixer chamber 116B is fluidly coupled to the top of the second side S2 of the second micromixer chamber 116B (opposite the first side S1) and is adjacent to a fourth vertex VX4 that is diagonally opposite the third vertex VX3, and the outlet 122B is oriented perpendicular to the plane defined by the second side S2 of the second micromixer chamber 116B.

[0041] In the example of the IHS structure 510, the first closed-loop microchannel structure 114A is disposed adjacent to (e.g., closer to) the tube core 104 below, while the second closed-loop microchannel structure 114B and the third closed-loop microchannel structure 114C are disposed above the first closed-loop microchannel structure 114A. Therefore, the second closed-loop microchannel structure 114B and the third closed-loop microchannel structure 114C are disposed farther away from the tube core 104 than the first closed-loop microchannel structure 114A. In various embodiments, the IHS structure 510 includes a first pump 124 coupled to the first inlet 118, a second pump 126 coupled to the second inlet 120, and a third pump 128 coupled to the third inlet 121 to control the liquid injected into each of the first micromixer chamber 116A and the second micromixer chamber 116B through the corresponding inlet of the first inlet 118, the second inlet 120, and the third inlet 121. In some examples, a pump may also be disposed along the outlet 122A (which is the inlet of the second micromixer chamber 116B).

[0042] During operation of the IHS structure 510, as liquid travels through the microchannels 112 of the first closed-loop microchannel structure 114A adjacent to the wick 104, the heat 125A generated by the wick 104 will be primarily transferred to the liquid flowing through the first closed-loop microchannel structure 114A. Therefore, the liquid entering the first micromixer chamber 116A via the first inlet 118 (hot inlet) may be hotter than the liquid entering the first micromixer chamber 116A via the second inlet 120 (cold inlet). The liquid flowing out of the outlet 122A (having been at least partially cooled via the first micromixer chamber 116A) is provided to the second micromixer chamber 116B and may be at least somewhat warmer than the liquid entering the second micromixer chamber 116B via the third inlet 121 (cold inlet). The liquid flowing out of the outlet 122B (which has been further cooled via the second micromixer chamber 116B) will be separated at the microchannel joint 112A, wherein a first portion of the liquid passes through the first closed-loop microchannel structure 114A, and a second portion of the liquid passes through the second closed-loop microchannel structure 114B and the third closed-loop microchannel structure 114C (e.g., the second portion of the liquid separated at the microchannel joint 112B is directed to each of the first micromixer chamber 116A and the second micromixer chamber 116B). In this example, as the liquid travels adjacent to the top surface of the IHS structure 510, heat 125B can be largely transferred away from the IHS structure 510 via the microchannels 112 of the second closed-loop microchannel structure 114B and the third closed-loop microchannel structure 114C, thereby ensuring that the liquid entering the first micromixer chamber 116A and the second micromixer chamber 116B via the second inlet 120 and the third inlet 121, respectively, remains cooler than the liquid entering the first micromixer chamber 116A via the first inlet 118, or cooler than the liquid entering the second micromixer chamber 116B via the outlet 122A. It should be noted that in some cases, the second closed-loop microchannel structure 114B can be larger than the third closed-loop microchannel structure 114C, so that the liquid flowing through the second closed-loop microchannel structure 114B can have more time (travel distance of the microchannels 112) to cool. In this case, the liquid entering the first micromixer chamber 116A via the second inlet 120 may be at least somewhat cooler than the liquid entering the second micromixer chamber 116B via the third inlet 121 .

[0043] In the example of the IHS structure 510, each of the first micro-mixer chamber 116A and the second micro-mixer chamber 116B provides mixing of hot liquid / cold liquid entering via the corresponding hot inlet / cold inlet, resulting in enhanced heat exchange at the outlets 122A, 122B. For example, in the IHS structure 510, the relative distance between the inlets 118, 120 and the outlet 122A is greater than the distance between the inlets 118, 120 and the outlet 122 in the IHS structure 110. In addition, in the IHS structure 510, the additional micro-mixer chamber (the second micro-mixer chamber 116B) provides increased heat exchange and overall increased cooling. In some examples, each of the multiple micro-mixer chambers 116A, 116B can be described as a cooling stage or a heat exchange stage. Therefore, it will be understood that as the number of micro-mixer chambers increases, the heat exchange efficiency of the IHS structure will also increase. The total number of micro-mixer chambers that can be implemented in a given IHS structure can be based on the manufacturing process and size of the IHS structure, but in some examples, the total number of micro-mixer chambers in a given IHS structure can be in the range of about 1-5. In other examples, the total number of micro-mixer chambers in a given IHS structure can be in the range of about 1-10.

[0044] Figure 6A cross-sectional view of a semiconductor or IC structure 600 is shown, which includes a substrate 102, a die 104, and an integrated heat sink (IHS) structure 610 coupled to the die 104 using a TIM layer 108. The substrate 102, the die 104, and the TIM layer 108 can be substantially the same as discussed above. Like the IHS structure 110, the IHS structure 610 includes a plurality of microchannels 112 and a micromixer chamber 116 (having an exemplary square or rectangular shape as discussed above), which together provide a first closed-loop microchannel structure 114A and a second closed-loop microchannel structure 114B, through which a liquid coolant is configured to flow. However, compared to the IHS structure 110, the configuration of the IHS structure 610 provides different positions and orientations of the first inlet 118 and the second inlet 120 relative to the micromixer chamber 116, thereby providing a different heat exchange efficiency than the IHS structure 110. For example, in the IHS structure 610, the first inlet 118 is fluidly coupled to the third vertex VX3 of the micromixer chamber 116 and is oriented substantially coplanar with the first diagonal plane P1 including the third vertex VX3. In some cases, the first inlet 118 may be optionally fluidly coupled to the first side S1 or the third side S3 of the micromixer chamber 116 (adjacent to the third vertex VX3 of the micromixer chamber 116 and oriented along an adjacent diagonal plane parallel to the first diagonal plane P1 including the third vertex VX3). In addition, in some examples, the second inlet 120 is fluidly coupled to the first vertex VX1 of the micromixer chamber 116 and is oriented substantially coplanar with the second diagonal plane P2 including the first vertex VX1. In some cases, the second inlet 120 may be optionally fluidly coupled to the first side S1 or the fourth side S4 of the micromixer chamber 116 (adjacent to the first vertex VX1 of the micromixer chamber 116 and oriented along an adjacent diagonal plane parallel to the second diagonal plane P2 including the first vertex VX1). As shown, the outlet 122 is fluidly coupled to a central portion of the second side S2 of the micro-mixer chamber 116 (opposite the first side S1 ), and the outlet 122 is oriented perpendicular to a plane defined by the second side S2 of the micro-mixer chamber 116 .

[0045] In the example of the IHS structure 610, as with the IHS structure 110, the first closed-loop microchannel structure 114A is disposed adjacent to (e.g., closer to) the underlying die 104, while the second closed-loop microchannel structure 114B is disposed above the first closed-loop microchannel structure 114A. Thus, the second closed-loop microchannel structure 114B is disposed farther from the die 104 than the first closed-loop microchannel structure 114A. In various embodiments, the IHS structure 610 (as with the IHS structure 110) includes a first pump 124 coupled to the first inlet 118 and a second pump 126 coupled to the second inlet 120 to control the liquid injected into the micromixer chamber 116 via respective ones of the first inlet 118 and the second inlet 120.

[0046] During operation of the IHS structure 610, as previously described, the heat 125A generated by the die 104 will be primarily transferred to the liquid flowing through the first closed-loop microchannel structure 114A, and as the liquid travels adjacent to the top surface of the IHS structure 610, the heat 125B may be primarily transferred from the IHS structure 610 via the microchannels 112 of the second closed-loop microchannel structure 114B. Therefore, the liquid entering the micromixer chamber 116 via the first inlet 118 (hot inlet) may be hotter than the liquid entering the micromixer chamber 116 via the second inlet 120 (cold inlet). The micromixer chamber 116 including the hot inlet and the cold inlet (the first inlet 118 and the second inlet 120) provides mixing of the hot liquid / cold liquid entering the hot inlet / cold inlet, resulting in enhanced heat exchange at the outlet 122. In particular, according to various embodiments, the arrangement of the first inlet 118 and the second inlet 120 in the IHS structure 610 provides different heat exchange efficiencies compared to the IHS structure 110 to accommodate different heat sinks, different dies, or different die packages.

[0047] Figure 7A cross-sectional view of a semiconductor or IC structure 700 is shown, which includes a substrate 102, a die 104, and an integrated heat sink (IHS) structure 710 coupled to the die 104 using a TIM layer 108. The substrate 102, the die 104, and the TIM layer 108 can be substantially the same as discussed above. The IHS structure 710 is similar in many respects to the IHS structure 610 discussed above. However, compared to the IHS structure 610, the configuration of the IHS structure 710 provides a different position and orientation of the first inlet 118 and the second inlet 120 relative to the micro-mixer chamber 116, thereby providing a different heat exchange efficiency than the IHS structure 610. For example, in the IHS structure 710, the first inlet 118 is fluidly coupled to the third side S3 of the micro-mixer chamber 116 (adjacent to the third vertex VX3 of the micro-mixer chamber 116 and oriented along a diagonal plane parallel to the second diagonal plane P2 including the first vertex VX1 of the micro-mixer chamber). Additionally, in some examples, the second inlet 120 is fluidly coupled to a fourth side S4 (adjacent to the first vertex VX1 of the micromixer chamber 116 and oriented along a diagonal plane parallel to the first diagonal plane P1 including the third vertex VX3) of the micromixer chamber 116. As shown, the outlet 122 is fluidly coupled to a central portion of the second side S2 of the micromixer chamber 116 (opposite to the first side S1), and the outlet 122 is oriented perpendicular to a plane defined by the second side S2 of the micromixer chamber 116.

[0048] Figure 8 A cross-sectional view of a semiconductor or IC structure 800 is shown, which includes a substrate 102, a die 104, and an integrated heat sink (IHS) structure 810 coupled to the die 104 using a TIM layer 108. The substrate 102, the die 104, and the TIM layer 108 can be substantially the same as discussed above. The IHS structure 810 is similar in many respects to the IHS structure 410 discussed above. However, compared to the IHS structure 410, the IHS structure 810 provides a different configuration, including an additional inlet 121 of the micro-mixer chamber 116, thereby providing a different heat exchange efficiency than the IHS structure 410. In addition to the first inlet 118, the second inlet 120, and the outlet 122 fluidly coupled to the micro-mixer chamber 116, as discussed above with reference to the IHS structure 410, the IHS structure 810 also includes a third inlet 121, which is fluidly coupled to a lateral portion of the third side S3 of the micro-mixer chamber 116 adjacent to the second vertex VX2 of the micro-mixer chamber 116. The third inlet 121 is oriented perpendicular to the outlet 122 and to a plane defined by the third side S3 of the micromixer chamber 116 .

[0049] Fig. 9A cross-sectional view of a semiconductor or IC structure 900 is shown, which includes a substrate 102, a die 104, and an integrated heat sink (IHS) structure 910 coupled to the die 104 using a TIM layer 108. The substrate 102, the die 104, and the TIM layer 108 can be substantially the same as discussed above. The IHS structure 910 is similar in many respects to the IHS structure 710 discussed above. However, compared to the IHS structure 710, the configuration of the IHS structure 910 provides a different position of the first inlet 118 and the second inlet 120 relative to the micro-mixer chamber 116, thereby providing a different heat exchange efficiency than the IHS structure 710. For example, in the IHS structure 910, the first inlet 118 is fluidly coupled to a third side S3 of the micro-mixer chamber 116 (adjacent to the second vertex VX2 of the micro-mixer chamber 116 and oriented along a diagonal plane parallel to a second diagonal plane P2 including the first vertex VX1 and the second vertex VX2 of the micro-mixer chamber 116). In addition, in some examples, the second inlet 120 is fluidly coupled to the fourth side S4 of the micromixer chamber 116 (adjacent to the fourth vertex VX4 of the micromixer chamber 116 and oriented along a diagonal plane parallel to the first diagonal plane P1 including the third vertex VX3 and the fourth vertex VX4 of the micromixer chamber 116). In other words, in the IHS structure 910, the positions along the respective third side S3 and fourth side S4 of the micromixer chamber 116 are offset compared to the IHS structure 710, and the respective inlets of the first inlet 118 and the second inlet 120 are fluidly coupled at these positions. As shown, the outlet 122 is fluidly coupled to the central portion of the second side S2 of the micromixer chamber 116 (opposite to the first side S1), and the outlet 122 is oriented perpendicular to the plane defined by the second side S2 of the micromixer chamber 116.

[0050] Fig.10A cross-sectional view of a semiconductor or IC structure 1000 is shown, which includes a substrate 102, a die 104, and an integrated heat sink (IHS) structure 1010 coupled to the die 104 using a TIM layer 108. The substrate 102, the die 104, and the TIM layer 108 can be substantially the same as discussed above. The IHS structure 1010 is similar in many respects to the IHS structure 410 discussed above. However, compared to the IHS structure 410, the IHS structure 1010 provides a different configuration, including a different position and orientation of the first inlet 118 and the second inlet 120 relative to the micro-mixer chamber 116, thereby providing a different heat exchange efficiency than the IHS structure 410. For example, in the IHS structure 1010, the first inlet 118 is fluidly coupled to the top of the second side S2 of the micro-mixer chamber 116 adjacent to the fourth vertex VX4 of the micro-mixer chamber 116, and the second inlet 120 is fluidly coupled to the lateral portion of the fourth side S4 of the micro-mixer chamber 116 adjacent to the fourth vertex VX4. The first inlet 118 and the second inlet 120 are also oriented perpendicularly to each other, and are perpendicular to the corresponding plane orientation defined by the second side S2 and the fourth side S4 of the micro-mixer chamber 116. As shown, the outlet 122 is fluidly coupled to the bottom (opposite to the first side S1) of the second side S2 of the micro-mixer chamber 116, and is adjacent to the second vertex VX2. Therefore, the first inlet 118 and the outlet 122 are fluidly coupled to different parts of the same side (second side S2) of the micro-mixer chamber 116. As shown, the outlet 122 is also perpendicular to the plane orientation defined by the second side S2 of the micro-mixer chamber 116.

[0051] Although Figure 1 and Figures 4 to 10 The examples of provide exemplary embodiments of various designs of IHS structures, but it will be understood that these examples are not meant to be limiting and that other embodiments having other configurations may be equally implemented without departing from the scope of the present disclosure. As an example, one or more of the plurality of microchannels 112 employed in the IHS structure may have a curved or curvilinear shape (e.g., as viewed from a top view or a side view), may have various cross-sectional shapes through which liquid flows (e.g., such as square, rectangular, circular, oval, elliptical, triangular, trapezoidal, hexagonal, pentagonal, or other polygonal shapes), and / or may be arranged in any of a variety of orientations relative to each other and relative to one or more micromixer chambers. As another example, although Figure 1 and Figures 4 to 10The embodiments show an IHS structure having a single IHS device (e.g., including corresponding microchannels, micromixer chambers, and closed-loop microchannel structures) disposed above a given die, but in some cases, an HIS structure having two or three IHS devices (each with their own corresponding microchannels, micromixer chambers, and closed-loop microchannel structures) can be disposed above a given die (e.g., by reducing the microchannel path of each of the multiple HIS devices). Regardless of the exact configuration of the IHS structure, each of the various designs can provide different heat exchange efficiencies to accommodate different heat sinks, different dies, or different die packages. In other words, regardless of the exact configuration of the IHS structure, the various designs shown and described herein can be used to accommodate different types of heat generating devices that generate different amounts of heat.

[0052] Reference now Fig.11 , which shows an integrated circuit (IC) cooling assembly 1100 including an integrated heat sink (IHS) structure according to some embodiments. As shown, the IC cooling assembly 1100 includes a substrate 102 (e.g., such as a package substrate), a die 104 (e.g., flip-chip bonded to the substrate 102), and an underfill 1118 disposed between the die 104 and the substrate 102. As previously discussed, the IHS structure 1110 is coupled to the die 104 using the TIM layer 108. In addition, because the IHS structure 1110 has a larger surface area than the die 104, stiffeners or pillars 1112 can be coupled between the lateral ends of the IHS structure 1100 and the underlying substrate 102 (e.g., using a suitable adhesive) to provide additional support for the IHS structure 110. Of course, in some cases, the IHS structure 1110 can be implemented as part of a package lid that contacts and / or bonds to the substrate 102 without a separate stiffener or pillar 1112. In some embodiments, the IC cooling assembly 1100 also includes an external heat sink 1114 coupled to the top surface of the IHS structure 1110 using a TIM layer 1116. In some examples, the TIM layer 1116 can be similar to the TIM layer 108. In particular, due to the larger surface area compared to the die 104, the IHS structure 1110 can include multiple IHS devices 1110A, 1110B, 1110C (each having their own corresponding microchannels, micromixer chambers, and closed-loop microchannel structures). Although each of the IHS devices 1110A, 1110B, 1110C of the IHS structure 1110 is shown as having Figure 1 However, it will be appreciated that in various embodiments, as discussed above, each of the IHS devices 1110A, 1110B, and 1110C may have a configuration similar to that of the IHS structure 110. Figure 1 and Figures 4 to 10. Therefore, the IC cooling assembly 1100 having multiple IHS devices 1110A, 1110B, 1110C and an external heat sink 1114 will provide greatly enhanced heat exchange and increased cooling of the tube core 104. In addition, according to the embodiments disclosed herein, even without the external heat sink 1114, the multiple IHS devices 1110A, 1110B, 1110C and their corresponding microchannels, micromixer chambers, and closed-loop microchannel structures will provide enhanced heat exchange and increased cooling of the tube core 104. In addition, although the IC cooling assembly 1100 is shown as including three IHS devices 1110A, 1110B, 1110C, it will be understood that the IC cooling assembly 1000 may include more than three IHS devices. For example, Fig.11A As shown in the exemplary top view of the IC cooling assembly 1100, the IHS structure 1110 may include a 3x3 array of IHS devices, such as IHS devices 1110A-1110I. In some cases, the IHS structure 1110 may alternatively include a 4x4 array or a 5x5 array of IHS devices (e.g., by reducing the microchannel path of each of the plurality of IHS devices). Generally, in various other embodiments, the IHS structure 1110 may include an array of IHS devices having a different number of IHS devices (e.g., depending on the design / configuration of each of the plurality of IHS devices formed as part of the IHS structure 1100).

[0053] refer to Fig. 12A and Fig. 12B , which shows a portion of an IC cooling assembly (such as reference Fig.11 ), further illustrating the substrate 102 mounted on the underlying PCB 1202. Fig. 12A and Fig. 12B100 is provided to illustrate an example of providing power and control signals to pumps (e.g., such as EHD pumps) of various IHS devices disposed within the IHS structure 1110. In some cases, the power / control circuit 1204 can be coupled to the IHS structure 1110 (e.g., along a side of the IHS structure 1110, embedded within the IHS structure 1110, such as on top of the IHS structure 1110 when an external heat sink 1114 is not used), the power / control circuit 1204 can be coupled to a surface of the PCB 1202, or the power / control circuit 1204 can be disposed on a top surface of the substrate 102 (e.g., adjacent to the die 104). Regardless of where the power / control circuit 1204 is disposed, electrical connections can be provided from the PCB 1202 and / or the substrate 102 to each pump of the IHS devices disposed within the IHS structure 1110 through wires, electrical traces, vias, bumps, balls, posts, or other suitable conductive layers. The electrical connections may in turn be used to provide OIP control for each pump that injects liquid into the micromixer chamber, and to provide power to operate the pumps (eg, to provide an applied voltage to the EHD pumps).

[0054] refer to Fig.13 , shows a general method 1300 for cooling an integrated circuit (IC) die using an IHS structure (such as the IHS structure discussed above) according to some embodiments. For clarity, the following reference is made to the IHS structure discussed above. Figure 1 , Figure 2A and Figure 2B Method 1300 is described in further detail. However, it will be understood that the steps described with reference to method 1300 can be equally applied to other IHS structures, such as with reference to Figures 4 to 10 those described, or used for Fig.11 , Fig. 12A and Fig. 12B Furthermore, it will be appreciated that additional process steps may be implemented before, during, and after the method 1300, and that some of the process steps described may be replaced or eliminated according to various embodiments of the method 1300.

[0055] Method 1300 begins at block 1302, where an IHS structure is provided over a die. For purposes of this discussion, and with reference to Figure 1, an IHS structure 110 is provided above the die 104, wherein the IHS structure 110 is coupled to the die 104 using the TIM layer 108. As discussed above, the IHS structure 110 includes a plurality of microchannels 112 and a micro-mixer chamber 116, which together provide a first closed-loop microchannel structure 114A and a second closed-loop microchannel structure 114B, and a liquid coolant is configured to flow through the first closed-loop microchannel structure 114A and the second closed-loop microchannel structure 114B. As discussed, the first closed-loop microchannel structure 114A and the second closed-loop microchannel structure 114B are fluidly coupled to the micro-mixer chamber 116 through a first inlet 118 (hot inlet) and a second inlet 120 (cold inlet), respectively. In addition, the first closed-loop microchannel structure 114A and the second closed-loop microchannel structure 114B are fluidly coupled to the micro-mixer chamber 116 through an outlet 122. As previously described, the second closed-loop microchannel structure 114B is further away from the die 104 than the first closed-loop microchannel structure 114A. The first pump 124 (coupled to the first inlet 118) is used to control the liquid injected into the micromixer chamber 116 via the first inlet 118, and the second pump 126 (coupled to the second inlet 120) is used to control the liquid injected into the micromixer chamber 116 via the second inlet 120.

[0056] The method 1300 proceeds to block 1304 where the liquid (e.g., water, magnetic fluid, or other working fluid) that has passed through the first closed-loop microchannel structure 114A is injected into the micromixer chamber 116 via the first inlet 118 (e.g., when no liquid is injected via the second inlet 120). Figure 2A In the example of block 1304, liquid may be injected into the micro-mixer chamber 116 at a first velocity V1 via the first inlet 118. A first control pulse (e.g., provided by an OIP controller) for controlling the first pump 124 to inject liquid into the micro-mixer chamber 116 via the first inlet 118 may have a first height H1 (corresponding to the first velocity V1), and the first control pulse may have a first pulse width corresponding to a first duration T1.

[0057] The method 1300 proceeds to block 1306, where the liquid that has passed through the second closed-loop microchannel structure 114B is injected into the micromixer chamber 116 via the second inlet 120 (eg, when no liquid is injected via the first inlet 118). Referring still to FIG. Figure 2AIn the embodiment of block 1306, liquid may be injected into the micro-mixer chamber 116 at a first velocity V1 via the second inlet 120. A second control pulse (e.g., provided by the OIP controller) for controlling the second pump 126 to inject liquid into the micro-mixer chamber 116 via the second inlet 120 may have a second height H2 (substantially equal to the first height H1 and corresponding to the first velocity V1), and the second control pulse may have a second pulse width corresponding to a second duration T2 (substantially equal to the first duration T1 of the first control pulse).

[0058] In the present example, the liquid is injected through each of the first inlet 118 and the second inlet 120 at substantially the same speed (first speed V1) while being phase-shifted (in time) from each other so that at any given time, only one of the first inlet 118 and the second inlet 120 injects the liquid into the micro-mixer chamber 116. In other words, the liquid may be injected through each of the first inlet 118 and the second inlet 120 at different times. In at least some optional embodiments, the liquid may be injected into the micro-mixer chamber 116 through each of the first inlet 118 and the second inlet 120 at the same time or at partially overlapping times. In addition, in some cases, the liquid injected through each of the first inlet 118 and the second inlet 120 may have different speeds. In other cases, different amounts of liquid may be injected through each of the first inlet 118 and the second inlet 120 (e.g., by controlling the first pulse width and the second pulse width corresponding to the respective control pulses of the first control pulse and the second control pulse).

[0059] In some embodiments, after block 1306, method 1300 then returns to block 1304, where liquid is again injected into micro-mixer chamber 116 via first inlet 118 (e.g., when no liquid is injected via second inlet 120), and then proceeds to block 1306 again, where liquid is injected into micro-mixer chamber 116 via second inlet 120 (e.g., when no liquid is injected via first inlet 118). In some cases, the loop of blocks 1304-1306 may continue to repeat as long as die 104 is operable (e.g., receiving power), as long as die 104 operates at a temperature above a given threshold temperature (e.g., as determined by a local temperature sensor), or as long as otherwise needed or desired. In some examples, while the loop of blocks 1304-1306 may continue, the parameters of the first control pulse and the second control pulse may vary between loops (or during a given loop). For example, one or more subsequent cycles of blocks 1304-1306 may vary the pulse height (and therefore the rate at which liquid is injected) and / or the pulse width (and therefore the amount of liquid injected).

[0060] In an optional embodiment of method 1300, at block 1304, and with reference to Figure 2B , the liquid may be injected into the micro-mixer chamber 116 at a first speed V2 via the first inlet 118. A first control pulse (e.g., provided by the OIP controller) for controlling the first pump 124 to inject the liquid into the micro-mixer chamber 116 via the first inlet 118 may have a first height H3 (corresponding to the first speed V2), and the first control pulse may have a first pulse width corresponding to a first duration T3.

[0061] In an alternative embodiment of method 1300, at block 1306, and still referring to Figure 2B , the liquid may be injected into the micro-mixer chamber 116 at a first velocity V2 via the second inlet 120. A second control pulse (e.g., provided by the OIP controller) for controlling the second pump 126 to inject the liquid into the micro-mixer chamber 116 via the second inlet 120 may have a second height H4 (substantially equal to the first height H3 and corresponding to the first velocity V2), and the second control pulse may have a second pulse width corresponding to a second duration T4 (substantially equal to the first duration T3 of the first control pulse).

[0062] In an alternative embodiment of the method 1300, after block 1306, the method 1300 then returns to repeat the loop of blocks 1304-1306. However, in subsequent iterations of blocks 1304-1306, the pulse height of each of the first control pulse and the second control pulse (and therefore the speed of the liquid injected into the micromixer chamber) may be varied. For example, in subsequent iterations of block 1304, and again referring to Figure 2B , the liquid may be injected into the micro-mixer chamber 116 via the first inlet 118 at a second speed V3 different from the first speed V2. A first control pulse (e.g., provided by the OIP controller) for controlling the first pump 124 to inject the liquid into the micro-mixer chamber 116 via the first inlet 118 may have a third height H5 (corresponding to the second speed V3), and the first control pulse may have a third pulse width corresponding to a third duration T5 (substantially equal to the first duration T3 and the second duration T4). Thereafter, in a subsequent loop of block 1306, and still with reference to Figure 2B , the liquid may be injected into the micro-mixer chamber 116 at a second speed V3 via the second inlet 120. A second control pulse (e.g., provided by the OIP controller) for controlling the second pump 126 to inject the liquid into the micro-mixer chamber 116 via the second inlet 120 may have a fourth height H6 (substantially equal to the third height H5 and corresponding to the second speed V3), and the second control pulse may have a fourth pulse width corresponding to a fourth duration T6 (substantially equal to the first duration T3, the second duration T4, and the third duration T5).

[0063] In some cases, and in optional embodiments of method 1300, the loop of blocks 1304-1306 (in which different pairs of control pulses with matching speeds are phase-shifted (in time) from one another so that only one of the first inlet 118 and the second inlet 120 injects liquid into the micromixer chamber 116 at any given time) may continue to repeat as long as the die 104 is operational (e.g., receiving power), as long as the die 104 operates at a temperature above a given threshold temperature (e.g., as determined by a local temperature sensor), or as long as otherwise needed or desired. Generally, as previously described, while the loop of blocks 1304-1306 may continue, the parameters of the first control pulse and the second control pulse may vary between cycles (or during a given cycle). For example, one or more subsequent cycles of blocks 1304-1306 may vary the pulse height (and therefore the speed at which liquid is injected) and / or the pulse width (and therefore the amount of liquid injected).

[0064] Therefore, the various embodiments described herein provide several advantages over the prior art. It will be understood that not all advantages are necessarily discussed herein, no particular advantage is required for all embodiments, and other embodiments may provide different advantages. As an example, the embodiments discussed herein include IHS structures and related methods, which support thermal cooling of IC dies and packages and are effectively used to overcome various shortcomings of existing methods. In some embodiments, the IHS structure includes a plurality of closed-loop microchannels, which are coupled to a hybrid active-passive micro-mixer chamber to improve the heat exchange efficiency of the IHS structure for use in high-performance computing package products. The IHS structure may be disposed above a die or die package, wherein a TIM layer is disposed between the IHS structure and the die or die package. The IHS structure may include a first microchannel adjacent to the die or die package and a second microchannel disposed above the first microchannel, the second microchannel being further away from the die or die package than the first microchannel. In various embodiments, the micro-mixer chamber is coupled to the first microchannel and the second microchannel via corresponding inlet and outlet fluids. The inlets of the first microchannel and the second microchannel may be coupled to a pump, and an OIP controller may be used to control the pump. The OIP controller provides control of the liquid injected into the micromixer chamber (e.g., by controlling the liquid velocity and phase (in time)). The micromixer chamber and microchannel inlet can have a variety of designs, each of which can provide different heat exchange efficiencies to accommodate different heat sinks, different dies, or different die packages. Regardless of the specific design of the IHS structure, and regardless of the liquid used as a coolant in the IHS structure, embodiments of the present disclosure provide improved thermal cooling of IC dies and packages, thereby directly addressing the IC thermal management challenges associated with advanced IC circuits and devices. Additional benefits and / or other advantages will become apparent to those skilled in the art having the benefit of this disclosure.

[0065] Therefore, one embodiment of the present disclosure describes a device that includes an integrated circuit die and an integrated heat sink structure disposed above the integrated circuit die. In some embodiments, the integrated heat sink structure includes a first closed-loop microchannel structure adjacent to the integrated circuit die and a second closed-loop microchannel structure disposed above the first closed-loop microchannel structure. In an example, the second closed-loop microchannel structure is disposed farther away from the integrated circuit die than the first closed-loop microchannel structure. In some embodiments, a plurality of microchannels and a micromixer chamber together provide a first closed-loop microchannel structure and a second closed-loop microchannel structure.

[0066] In some embodiments, the first closed-loop microchannel structure is fluidly coupled to the micromixer chamber via a first inlet and an outlet, and wherein the second closed-loop microchannel structure is fluidly coupled to the micromixer chamber via a second inlet and the outlet.

[0067] In some embodiments, the first closed-loop microchannel structure is fluidly coupled to the micromixer chamber via a first inlet and an outlet, and wherein the second closed-loop microchannel structure is fluidly coupled to the micromixer chamber via a second inlet and the outlet, the device further comprising a first pump coupled to the first inlet and a second pump coupled to the second inlet.

[0068] In some embodiments, the first closed-loop microchannel structure is coupled to the micromixer chamber via a first inlet and an outlet fluid, and wherein the second closed-loop microchannel structure is coupled to the micromixer chamber via a second inlet and the outlet fluid, the device further comprising a first pump coupled to the first inlet and a second pump coupled to the second inlet, the first pump being configured to control liquid injected into the micromixer chamber via the first inlet, and wherein the second pump being configured to control liquid injected into the micromixer chamber via the second inlet.

[0069] In some embodiments, the first closed-loop microchannel structure is coupled to the micromixer chamber via a first inlet and an outlet fluid, and wherein the second closed-loop microchannel structure is coupled to the micromixer chamber via a second inlet and the outlet fluid, the device further comprising a first pump coupled to the first inlet and a second pump coupled to the second inlet, and an active oscillation input phase (OIP) controller is used to control the first pump and the second pump.

[0070] In some embodiments, the first closed-loop microchannel structure is fluidly coupled to the micromixer chamber via a first inlet and an outlet, and wherein the second closed-loop microchannel structure is fluidly coupled to the micromixer chamber via a second inlet and the outlet, the device further comprising a first pump coupled to the first inlet and a second pump coupled to the second inlet, at least one of the first pump and the second pump comprising an electro-fluid dynamic (EHD) pump.

[0071] In some embodiments, a ratio of a first width of the micromixer chamber to a second width of a microchannel of the plurality of microchannels is in a range between about 5:1 to about 15:1.

[0072] In some embodiments, the ratio of the width to the length of the micromixer chamber is in a range between about 1:1 to about 1:5.

[0073] In some embodiments, the liquid disposed within the plurality of microchannels includes water or a magnetic fluid.

[0074] In some embodiments, the second closed-loop microchannel structure is fluidly coupled to the micromixer chamber through the second inlet, the third inlet, and the outlet.

[0075] In another embodiment, an integrated circuit (IC) structure is discussed, including a die and an integrated heat sink disposed above the die. In some examples, the integrated heat sink includes a plurality of closed-loop microchannel structures and a first micromixer chamber. In some cases, the plurality of closed-loop microchannel structures are fluidically coupled to the first micromixer chamber via a first corresponding inlet, and the plurality of closed-loop microchannel structures are fluidically coupled to the first micromixer chamber via a first common outlet. In some embodiments, each first corresponding inlet includes a pump configured to control liquid injected into the first micromixer chamber via the first corresponding inlet.

[0076] In some embodiments, an active oscillating input phase (OIP) controller is used to control the pump.

[0077] In some embodiments, the pump comprises an electro-fluid dynamic (EHD) pump.

[0078] In some embodiments, the liquid includes water or a magnetic fluid.

[0079] In some embodiments, the integrated circuit structure further includes a layer of thermal interface material between the die and the integrated heat spreader.

[0080] In some embodiments, the integrated heat sink also includes a second micromixer chamber, wherein the plurality of closed-loop microchannel structures are fluidically coupled to the second micromixer chamber via a second corresponding inlet; wherein the plurality of closed-loop microchannel structures are fluidically coupled to the second micromixer chamber via a second common outlet; and wherein at least one of the second corresponding inlets includes the pump, which is configured to control the liquid injected into the second micromixer chamber via the at least one of the second corresponding inlets.

[0081] In some embodiments, the integrated heat sink also includes a second micromixer chamber, wherein the plurality of closed-loop microchannel structures are fluidically coupled to the second micromixer chamber via second corresponding inlet fluids; wherein the plurality of closed-loop microchannel structures are fluidically coupled to the second micromixer chamber via a second common outlet fluid; and wherein at least one of the second corresponding inlets includes the pump, the pump being configured to control the liquid injected into the second micromixer chamber via the at least one of the second corresponding inlets, wherein the first common outlet of the first micromixer chamber is fluidically coupled to the second micromixer chamber as one of the second corresponding inlets.

[0082] In yet another embodiment, a method is discussed, comprising: providing an integrated heat sink above a tube core. In some embodiments, the integrated heat sink comprises a first closed-loop microchannel structure coupled to a micromixer chamber via a first inlet fluid and a second closed-loop microchannel structure coupled to the micromixer chamber via a second inlet fluid. In some examples, a first pump is coupled to the first inlet and a second pump is coupled to the second inlet. In some embodiments, the method further comprises injecting a liquid into the micromixer chamber via the first inlet at a first speed. In some embodiments, the method further comprises injecting a liquid into the micromixer chamber via the second inlet at a second speed.

[0083] In some embodiments, the liquid is injected through each of the first inlet and the second inlet at different times.

[0084] In some embodiments, the first speed is substantially equal to the second speed.

[0085] The features of several embodiments are summarized above so that those skilled in the art can better understand aspects of the present disclosure. Those skilled in the art should understand that they can easily use the present disclosure as a basis to design or modify other processes and structures for implementing the same purpose and / or achieving the same advantages as the embodiments introduced herein. Those skilled in the art should also appreciate that such equivalent constructions do not deviate from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and modifications herein without departing from the spirit and scope of the present disclosure.

Claims

1. An integrated circuit structure, comprising: Integrated circuit die; as well as an integrated heat sink structure disposed above the integrated circuit die; The integrated heat sink structure includes a first closed-loop microchannel structure adjacent to the integrated circuit die and a second closed-loop microchannel structure disposed above the first closed-loop microchannel structure, wherein the second closed-loop microchannel structure is disposed farther away from the integrated circuit die than the first closed-loop microchannel structure; and Wherein, a plurality of microchannels and micromixer chambers together provide the first closed-loop microchannel structure and the second closed-loop microchannel structure.

2. The integrated circuit structure according to claim 1, wherein: The first closed-loop microchannel structure is fluidly coupled to the micromixer chamber via a first inlet and an outlet, and wherein the second closed-loop microchannel structure is fluidly coupled to the micromixer chamber via a second inlet and the outlet. 3 . The integrated circuit structure of claim 2 , further comprising a first pump coupled to the first inlet and a second pump coupled to the second inlet.

4. The integrated circuit structure according to claim 3, wherein: The first pump is configured to control liquid injected into the micromixer chamber via the first inlet, and wherein the second pump is configured to control the liquid injected into the micromixer chamber via the second inlet.

5. The integrated circuit structure according to claim 3, wherein: The first pump and the second pump are controlled using an active oscillating input phase (OIP) controller.

6. The integrated circuit structure according to claim 3, wherein: At least one of the first pump and the second pump comprises an electro-fluid dynamic (EHD) pump.

7. The integrated circuit structure according to claim 1, wherein: A ratio of a first width of the micromixer chamber to a second width of a microchannel of the plurality of microchannels is in a range between about 5:1 and about 15:

1.

8. The integrated circuit structure according to claim 1, wherein: The ratio of the width to the length of the micromixer chamber is in a range between about 1:1 to about 1:

5.

9. An integrated circuit (IC) structure comprising: Die; as well as an integrated heat sink disposed above the tube core, the integrated heat sink comprising a plurality of closed-loop microchannel structures and a first micro-mixer chamber; wherein the plurality of closed-loop microchannel structures are fluidically coupled to the first micromixer chamber via first corresponding inlet ports; wherein the plurality of closed-loop microchannel structures are coupled to the first micromixer chamber via a first common outlet fluid; and Wherein each of the first respective inlets comprises a pump configured to control liquid injected into the first micromixer chamber via the first respective inlet.

10. A method of forming an integrated circuit structure, comprising: providing an integrated heat sink over the die, wherein the integrated heat sink comprises a first closed-loop microchannel structure fluidly coupled to a micromixer chamber via a first inlet and a second closed-loop microchannel structure fluidly coupled to the micromixer chamber via a second inlet, and wherein a first pump is coupled to the first inlet and a second pump is coupled to the second inlet; injecting a liquid into the micromixer chamber via the first inlet at a first velocity; and The liquid is injected into the micromixer chamber via the second inlet at a second velocity.

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