Advanced packaging and thermal solution designs for high current density ics

Abstract

A device package comprising an integrated cooling assembly. The device package may comprise a semiconductor device, a cold plate attached to the semiconductor device, and a manifold attached to the cold plate. The manifold may comprise a plurality of coolant channels. For example, a first portion of the manifold may comprises a first coolant channel and a second coolant channel, a second portion of the manifold may comprises a third coolant channel and a fourth coolant channel, and a third portion of the manifold may comprises a fifth coolant channel and a sixth coolant channel. The coolant channels of the manifold may direct coolant to and from one or more coolant channels of the cold plate to increase thermal dissipation related to one or more hot spots, balance the coolant flow throughout the cold plate, and / or manipulate pressure drop.

Description

Docket No. 001453-0177-W01ADVANCED PACKAGING AND THERMAL SOLUTION DESIGNS FOR HIGH CURRENT DENSITY ICSCross-Reference to Related

[0001] This application claims the benefit of U.S. Patent Application No. 19 / 174,268, filed April 9, 2025 and U.S. Provisional Patent Application No. 63 / 780,032, filed March 28, 2025, which are incorporated by reference herein in its entirety.Background

[0002] The present disclosure relates to advanced packaging for microelectronic devices, and in particular, cooling systems for device packages and methods of manufacturing the same.Summary

[0003] Energy consumption poses a critical challenge for the future of large-scale computing as the world’s computing energy requirements are rising at a rate that most would consider unsustainable. Some models predict that the information, communication and technology (ICT) ecosystem could exceed 20% of global electricity use by 2030, with direct electrical consumption by large-scale computing centers accounting for more than one-third of that energy usage. A significant portion of the energy used by such large-scale computing centers is devoted to cooling, since even small increases in operating temperatures can negatively impact the performance of microprocessors, memory devices, and other electronic components. While some of this energy is expended to operate the cooling systems that are directly cooling the chips (e.g., heat spreaders, heat pipes, etc.), energy consumption / costs for indirect cooling can also be quite staggering. Indirect cooling energy costs include, for example, cooling or air conditioning of data center buildings. Data center buildings can house thousands, to tens of thousands or more, of high-performance chips in server racks, and each of those high-performance chips is a heat source. An uncontrolled ambient temperature in a data center will adversely affect the performance of the individual chips, and the data center system performance as a whole.

[0004] Thermal dissipation in high-power density chips (semiconductor devices / dies) is also a critical challenge as improvements in chip performance (e.g., through increased gate or transistor density due to advanced processing nodes, evolution of multi-core microprocessors,etc.) have resulted in increased power density and a corresponding increase in thermal flux that contributes to elevated chip temperatures. Higher density of transistors also increases the length of metal wiring on the chips, which generates its own additional thermal flux due to Joule heating of these wires due to higher currents. These elevated temperatures are undesirable as they can degrade the chip’s operating performance, efficiency, reliability, and amount of remaining life. Cooling systems used to maintain the chip at a desired operating temperature typically remove heat using one or more heat dissipation devices (e.g., thermal spreaders, heat pipes, cold plates, liquid cooled heat pipe systems, thermal-electric coolers, heat sinks, etc.). One or more thermal interface material(s) (e.g., thermal paste, thermal adhesive, and / or thermal gap filler), may be used to facilitate heat transfer between the surfaces of a chip and heat dissipation device(s). A thermal interface material(s) (TIM(s)) is any material that is inserted between two components to enhance the thermal coupling therebetween. Unfortunately, the combined thermal resistance of (i) the thermal resistance of interfacial boundary regions between a TIM(s) and the chip and / or the heat dissipation device(s), and (ii) the thermal resistance of a thermal interface material(s) itself can inhibit heat transfer from the chip to the heat dissipation devices, undesirably reducing the cooling efficiency of the cooling system.

[0005] Generally speaking, there are multiple components between the heat dissipating sources (i.e., active circuitry) in the chips and the heat dissipation devices, each of which contributes to the system thermal resistance cumulatively along the heat transfer paths and raises chip junction temperatures from the ambient. Such cooling systems can suffer from reduced cooling efficiency due to the design and manufacture of system components.

[0006] Accordingly, there exists a need in the art for improved energy -efficient cooling systems, by reducing system thermal resistance, and methods of manufacturing the same.Summary

[0007] Embodiments herein provide integrated cooling assemblies embedded in advanced device packages. Advantageously, the integrated cooling assemblies minimize or reduce system thermal resistance, minimize or reduce pressure drop by distributing flow in a design of the cold plate and / or manifold.

[0008] A first general aspect includes, a device package including a substrate, a first semiconductor device disposed on the substrate, a cold plate attached to the first semiconductor device, wherein the cold plate comprises a plurality of coolant channels, and amanifold attached to the cold plate. A first portion of the manifold may include a first coolant channel and a second coolant channel. A second portion of the manifold may include a third coolant channel and a fourth coolant channel. A third portion of the manifold may include a fifth coolant channel and a sixth coolant channel. The third portion of the manifold may be attached to the cold plate and the fifth coolant channel and the sixth coolant channel may be coupled to at least one coolant channel of the plurality of coolant channels of the cold plate. The second portion of the manifold may be between the first portion of the manifold and the third portion of the manifold.

[0009] In some embodiments, the first coolant channel is coupled to a first coolant line and the second coolant channel is coupled to a second coolant line.

[0010] In some embodiments, the third coolant channel is coupled to the first coolant channel and the fourth coolant channel is coupled to the second coolant channel. In some embodiments, the fifth coolant channel is coupled to the third coolant channel and the sixth coolant channel is coupled to the fourth coolant channel. In some embodiments, coolant is disposed in the first coolant channel, the second coolant channel, the third coolant channel, the fourth coolant channel, the fifth coolant channel, the sixth coolant channel, and the at least one coolant channel of the plurality of coolant channels of the cold plate.

[0011] In some embodiments, the cold plate is attached to the first semiconductor device by direct dielectric bonds. In some embodiments, the cold plate is attached to the first semiconductor device by direct hybrid bonds. In some embodiments, the manifold is attached to the cold plate using at least one of one or more adhesives, one or more gaskets, and one or more O-rings.

[0012] In some embodiments, the manifold comprises a plastic. In some embodiments, the manifold comprises a metal. In some embodiments, the manifold is attached to the cold plate using one or more adhesives. In some embodiments, the first portion of the manifold is attached to the second portion of the manifold using an adhesive material. In some embodiments, the second portion of the manifold is attached to the third portion of the manifold using an additional adhesive material.

[0013] In some embodiments, the third portion of the manifold comprises a seventh coolant channel and the plurality of coolant channels comprise a first cold plate coolant channel and a second cold plate coolant channel. In some embodiments, the fifth coolant channel is coupled to the first cold plate coolant channel and the seventh coolant channel is coupled to the second cold plate coolant channel. In some embodiments, the fifth coolant channeldelivers coolant at a first rate to the first cold plate coolant channel, the seventh coolant channel delivers coolant at a second rate to the second cold plate coolant channel and the first rate is different than the second rate. The first rate may be larger than the second rate and the first cold plate coolant channel may be disposed over a hot spot of the first semiconductor device. In some embodiments, the fifth coolant channel has a first characteristic, the seventh coolant channel has a second characteristic, and the first characteristic is different than the second characteristic. In some embodiments, the first characteristic corresponds to at least one of a length of the fifth coolant channel, a width of the fifth coolant channel, a height of the fifth coolant channel, a shape of the fifth coolant channel, and a diameter of the fifth coolant channel. In some embodiments, the first characteristic corresponds to a first diameter, the second characteristic corresponds to a second diameter, and the first diameter is larger than the second diameter.Brief Description of the Drawings

[0014] The above and other objects and advantages of the disclosure will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0015] FIG. 1 illustrates a device package with an external heat sink, in accordance with some embodiments of the disclosure;

[0016] FIG. 2A is a schematic plan view of an example of a system panel, in accordance with some embodiments of the present disclosure;

[0017] FIG. 2B is a schematic partial sectional side view of a device package mounted on a PCB, in accordance with some embodiments of the present disclosure;

[0018] FIG. 2C is a schematic exploded isometric view of the device package in FIG. 2B, in accordance with some embodiments of the present disclosure;

[0019] FIG. 3 is a schematic sectional view of an example device package that may be used with the system panel, in accordance with some embodiments of the present disclosure;

[0020] FIG. 4 is a schematic sectional view of an integrated cooling assembly of the device package, in accordance with some embodiments of the present disclosure;

[0021] FIG. 5 is a schematic sectional view of another example device package that may be used with the system panel, in accordance with some embodiments of the present disclosure;

[0022] FIG. 6 shows a method that can be used to manufacture the device package, in accordance with some embodiments of the present disclosure;

[0023] FIG. 7 illustrates portions of a manifold, in accordance with some embodiments of the present disclosure;

[0024] FIG. 8A shows a bottom view of a portion of a manifold, in accordance with some embodiments of the present disclosure;

[0025] FIG. 8B shows a top view of a portion of a manifold, in accordance with some embodiments of the present disclosure;

[0026] FIG. 9A shows a bottom view of a manifold, in accordance with some embodiments of the present disclosure;

[0027] FIG. 9B shows a top view of a manifold, in accordance with some embodiments of the present disclosure;

[0028] FIG. 10 illustrates a plurality of coolant channels within a manifold, in accordance with some embodiments of the present disclosure;

[0029] FIG. 11 illustrates a plurality of coolant channels within a manifold, in accordance with some embodiments of the present disclosure;

[0030] FIG. 12 illustrates a plurality of coolant channels within a manifold, in accordance with some embodiments of the present disclosure; and

[0031] FIG. 13 is a schematic sectional view of an example device package that may be used with the system panel, in accordance with some embodiments of the present disclosure.

[0032] The figures herein depict various embodiments of the present disclosure for purposes of illustration only. It will be appreciated that additional or alternative structures, assemblies, systems, and methods may be implemented within the principles set out by the present disclosure.Detailed Description

[0033] As used herein, the term “substrate” means and includes any workpiece, wafer, or article that provides a base material or supporting surface from which or upon which components, elements, devices, assemblies, modules, systems, or features of the heatgenerating devices, packaging components, and cooling assembly components described herein may be formed or mounted. The term “substrate” also includes “semiconductor substrates” that provide a supporting material upon which elements of a semiconductor device are fabricated or attached, and any material layers, features, and / or electronic devices formed thereon, therein, or therethrough. Examples of substrate material that may be used inapplications that generate high thermal density include, but are not limited to, Si, GaN, SiC, InP, GaP, InGaN, AlGalnP, AlGaAs, etc.

[0034] As described below, the semiconductor substrates herein generally have a “device side,” (e.g., the side on which semiconductor device elements are fabricated, such as transistors, resistors, and capacitors) and a “backside” that is opposite the device side. The term “active side” should be understood to include a surface of the device side of the substrate and may include the device side surface of the semiconductor substrate and / or a surface of any material layer, device element, or feature formed thereon or extending outwardly therefrom, and / or any openings formed therein. Thus, it should be understood that the material(s) that forms the active side may change depending on the stage of device fabrication and assembly. Similarly, the term “non-active side” (opposite the active side) includes the non-active side of the substrate at any stage of device fabrication, including the surfaces of any material layer, any feature formed thereon, or extending outwardly therefrom, and / or any openings formed therein. Thus, the terms “active side” or “non-active side” may include the respective surfaces of the semiconductor substrate at the beginning of device fabrication and any surfaces formed during material removal, (e.g., after substrate thinning operations). Depending on the stage of device fabrication or assembly, the terms “active sides” and “non-active sides” are also used to describe surfaces of material layers or features formed on, in, or through the semiconductor substrate, whether or not the material layers or features are ultimately present in the fabricated or assembled device. For example, in some instances, the term “active side” is used to indicate a surface of a substrate that will in the future, but does not yet, include semiconductor device elements.

[0035] Spatially relative terms are used herein to describe the relationships between elements, such as the relationships between substrates, heat-generating devices, cooling assembly components, device packaging components, and other features described below. Unless the relationship is otherwise defined, terms such as “above,” “over,” “upper,” “upwardly,” “outwardly,” “on,” “below,” “under,” “beneath,” “lower,” “top,” “bottom” and the like are generally made with reference to the X, Y, and Z directions set forth by X, Y and Z axes in the drawings. Thus, it should be understood that the spatially relative terms used herein are intended to encompass different orientations of the substrate and, unless otherwise noted, are not limited by the direction of gravity. Unless the relationship is otherwise defined, terms describing the relationships between elements such as “disposed on,” “embedded in,” “coupled to,” “connected by,” “attached to,” “bonded to,” and the like, eitheralone or in combination with a spatially relevant term, include both relationships with intervening elements and direct relationships where there are no intervening elements.Furthermore, the term “horizontal” is generally made with reference to the X-axis direction and the Y-axis direction set forth in the drawings. The term “vertical” is generally made with reference to the Z-axis direction set forth in the drawings.

[0036] Various embodiments disclosed herein include bonded structures in which two or more elements are directly bonded to one another without an intervening adhesive (referred to herein as “direct bonding,” “direct dielectric bonding,” or “directly bonded”). In some embodiments, direct bonding includes the bonding of a single material on the first of the two or more elements and a single material on a second one of the two or more elements, where the single material on the different elements may or may not be the same. For example, bonding a layer of one inorganic dielectric (e.g., silicon oxide) to another layer of the same or different inorganic dielectric. As discussed in more detail below, the process of direct bonding (e.g., direct dielectric bonding) provides a reduction of thermal resistance between a semiconductor device and a cold plate. Examples of dielectric materials used in direct bonding include oxides, nitrides, oxynitrides, carbonitrides, and oxycarbonitrides, etc., such as, for example, silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, etc. Direct bonding can also include bonding of multiple materials on one element to multiple materials on the other element (e.g., hybrid bonding). As used herein, the term “hybrid bonding” refers to a species of direct bonding having both i) at least one (first) nonconductive feature directly bonded to another (second) nonconductive feature, and ii) at least one (first) conductive feature directly bonded to another (second) conductive feature, without any intervening adhesive. The resultant bonds formed by this technique may be described as “hybrid bonds” and / or “direct hybrid bonds.” In some hybrid bonding embodiments, there are many first conductive features, each directly bonded to a second conductive feature, without any intervening adhesive. In some embodiments, nonconductive features on the first element are directly bond to nonconductive features of the second element at room temperature without any intervening adhesive, which is followed by bonding of conductive features of the first element directly bonded to conductive features of the second element via annealing at slightly higher temperatures (e.g., >100°C, >200°C, >250°C, >300°C, etc.)

[0037] Unless otherwise noted, the terms “cooling assembly” and “integrated cooling assembly” generally refer to a semiconductor device and a cold plate attached to thesemiconductor device. Typically, the cold plate is formed with recessed surfaces that define one or more fluid cavities (e.g., coolant chamber volume(s) or coolant channel(s)) between the cold plate and the semiconductor device. In embodiments where the cold plate is formed with plural fluid cavities, each fluid cavity may be defined by cavity dividers and / or sidewalls of the cold plate. For example, cavity dividers may be spaced apart from each other and extend laterally between opposing cold plate sidewalls (e.g., in one direction between a first pair of opposing cold plate sidewalls, or in two directions between orthogonal pairs of opposing cold plate sidewalls). The cavity dividers and the cold plate sidewalls may collectively define adjacent fluid cavities therebetween. The cold plate may comprise a polymer material.

[0038] The cold plate may be attached to the semiconductor device by use of a compliant adhesive layer or by direct bonding or hybrid bonding. Direct bonding may include direct dielectric bonding techniques as described herein, and may give rise to direct dielectric bonds. Hybrid bonding may include hybrid bonding techniques as described herein, and may give rise to direct hybrid bonds. For example, the cold plate may include material layers and / or metal features that facilitate direct bonding or hybrid bonding with the semiconductor device. Beneficially, the backside of the semiconductor device is directly exposed to coolant fluids flowing through the integrated cooling assembly, thus providing for direct heat transfer therebetween. Unless otherwise noted, the integrated cooling assemblies described herein may be used with any desired fluid (e.g., liquid, gas, and / or vapor-phase coolants, such as water, glycol, etc.). In some embodiments, the coolant fluid(s) may contain additives to enhance the conductivity of the coolant fluid(s) within the integrated cooling assemblies. The additives may comprise, for example, nano-particles of carbon nanotubes, nano-particles of graphene, and / or nano-particles of metal oxides. The concentration of these nano-particles may be less than 1%, less than 0.2%, or less than 0.05%. The coolant fluids may also contain a small amount of glycol or glycols (e.g., propylene glycol, ethylene glycol, etc.) to reduce frictional shear stress and drag coefficient in the coolant fluid(s) within the integrated cooling assembly.

[0039] Exemplary fluids available for use in the various thermal solution embodiments include: water (either purified or deionized), a glycol (e.g., ethylene glycol, propylene glycol), glycols mixed with water (e.g., ethylene glycol mixed with water (EGW) or propylene glycol mixed with water (PGW)), dielectric fluids (e.g. fluorocarbons, polyalphaolefin (PAO), isoparaffins, synthetic esters, or very high viscosity index (VHVI)oils), or mineral oils. Additionally, depending upon design and operating conditions, these fluids may be used in single-phase liquid, single-phase vapor, two-phase liquid / vapor or two-phase solid / liquid. All of these fluids and fluid mixtures will alter the thermohydraulic and heat transfer properties by altering the temperatures where phase change occurs, as well as meeting design temperature and pressure conditions for the component being cooled or warmed and the thermal solution being deployed. Additionally, multiple combinations of the fluid phases may be employed in various hybrid configurations to meet the particular cooling or warming needs of a respective implementation and still be within the scope of the contemplated embodiments.

[0040] Additionally, in some embodiments part or all the cooling is provided by gases.Exemplary gases include atmospheric air and / or one or more inert gases such as nitrogen. Atmospheric air may be taken to mean the mixture of different gases in Earth’s atmosphere made up of about 78% nitrogen and 21% oxygen.

[0041] Depending on the design needs of a thermal solution system using the disclosed embodiments, engineered dielectric cooling fluids may be used. Some examples of dielectric fluids used for cooling semiconductors include: 3M™ Fluorinert™ Liquid FC-40 - A nonflammable, dielectric fluid that can be used in direct contact with live electronics; 3M™ Novec™ Engineered Fluids - A non-flammable, dielectric fluid that can be used in direct contact with live electronics; Galden® PFPE (perfluoropolyether) products used as heat transfer fluids; EnSolv Fluoro HTF - A solvent with a high boiling point and low pour point that can be used for semiconductor wafer cooling. It is understood that in the selection of the cooling fluid, system design aspects such as operating temperatures and pressures, fluid flow rates, fluid viscosity, and other properties will require evaluation when selecting the appropriate cooling fluid.

[0042] In some embodiments, the cooling fluids may contain microparticles and / or nanoparticle additives to enhance the conductivity of the cooling fluid within the integrated cooling assemblies. Choi and Eastman (1995) from Argonne National Laboratory, U.S.A. (Yu et al., 2007) coined the word “nanofluid.” Nanofluids are engineered fluids prepared by suspending the nano-sized (1-100 nm) particles of metals / non-metals and their oxide(s) with a base / conventional fluid. The suspension of high thermal conductivity metals / non-metals and their oxides nanoparticles enhances the thermal conductivity and heat transfer ability, etc. of the base fluid. The additives to the underlying cooling fluid may comprise for example, nanoparticles of carbon nanotube, nanoparticles of graphene, or nanoparticles of metaloxides. When the cooling fluid contains microparticles, the microparticles are typically 10 microns or less in diameter. Silicon oxide microparticles may be used.

[0043] The volume concentration of these micro or nanoparticles may be less than 1%, less than 0.2%, or less than 0.05%. Depending upon the liquid and micro / nanoparticle type chosen for the cooling fluid, higher volume concentrations of 10% or less, 5% or less, or 2% or less may be used. The cooling fluids may also contain small amounts of glycol or glycols (e.g., propylene glycol, ethylene glycol etc.) to reduce frictional shear stress and drag coefficient in the cooling fluid within the integrated cooling assembly. The availability of different base fluids (e.g., water, ethylene glycol, mineral or other stable oils, etc.) and different nanomaterials provide a variety of nanomaterial options for nanofluid solutions to be used in the various embodiments. These nanomaterial option groups such as aforementioned metals (e.g., Cu, Ag, Fe, Au, etc.), metal oxides (e.g., TiO2, A12O3, CuO, etc.), carbons (e.g., CNTS, graphene, diamond, graphite...etc.), or a mixture of different types of nanomaterials. Metal nanoparticles (Cu, Ag, Au...), metal oxide nanoparticles (A12O3, TiO2, CuO), and carbon-based nanoparticles are commonly employed elements. Silicon oxide nanoparticles may also be used. Using cooling fluids with micro and / or nanoparticles when practicing the various embodiments disclosed herein can result in increased heat removal efficiencies and effectiveness.

[0044] The fluid control design aspects of specific embodiments may require the nanofluids to be magnetic to facilitate either movement or cessation of movement of the fluids within the semiconductor structures. Magnetic nanofluids (MNFs) are suspensions of a non-magnetic base fluid and magnetic nanoparticles. Magnetic nanoparticles may be coated with surfactant layers such as oleic acid to reduce particle agglomeration and / or settling. Magnetic nanoparticles used in MNFs are usually made of metal materials (ferromagnetic materials) such as iron, nickel, cobalt, as well as their oxides such as spinel-type ferrites, magnetite (Fe3O4), and so forth. The magnetic nanoparticles used in MNFs typically range in size from about 1 to 100 nanometers (nm).

[0045] This disclosure describes embodiments involving the architecture of system and component elements that can be employed to provide for the cooling of semi-conductor components, packaging, and boards. However, those skilled in the art will appreciate the disclosed components and arrangements can be deployed and used in scenarios where component heat up or thermal warm up is desired for a component that is currently outside the low end of the desired operational range. Components that are outside the low end oftheir operational range can, if started in a cold environment, experience thermal warping or cracking up to and including thermal overexpansion and contact separation that may impair the successful operation of the system. Therefore, in these scenarios, the architectures and embodiments disclosed herein can be used where the indirect thermal solutions supporting them are repurposed or operated in a hybrid configuration to provide warming fluids or heat transfer media to accomplish the warm-up or heat-up scenario. These scenarios are controlled by systems not shown here to bring temperatures up at a speed or timing that enables the materials to avoid the excessive thermal expansion or unequal thermal expansion that may occur among the materials of the semiconductor or packaging being serviced by the thermal solution. Once the component or packaging is brought up into the normal operating range, it can be safely started and brought to a useful operational state.

[0046] Considering the warm-up or heat-up embodiments introduced above, the balance of this disclosure and terms used should be viewed in a light that also considers the design option for such warm-up or heat-up. Thus, where terms such as cooling channel, cooling chamber volume, cavity, and cooling port are used, for example, such terms could also be considered as a thermal control channel, a thermal control volume, or a thermal control port, respectively. A person of skill would understand that heat flux or heat transfer would go in a different direction, but the design concepts are similar and can be successfully employed in the various embodiments.

[0047] In some embodiments, a cooling channel is a liquid cooling channel, and a liquid may flow through the liquid cooling channel. In some embodiments, the liquid may comprise a water and / or glycol (e.g., propylene glycol, ethylene glycol, and mixtures thereof).

[0048] As described below, coolant fluid flowing through a cold plate may be used to control the temperature of semiconductor devices. The fluid flowing across the surface of the semiconductor device absorbs heat and conducts heat away from the semiconductor device.

[0049] FIG. 1 is a schematic side view of a device package 10 and a heat sink 22 attached to the device package 10. The device package 10 typically includes a package substrate 12, a first device 14, a device stack 15, a heat spreader 18, and first TIM layers 16A, 16B thermally coupling the first device 14 and the device stack 15 to the heat spreader 18. The device package 10 is thermally coupled to the heat sink 22 through a second TIM layer 20. The TIM layers 16A, 16B, 20 facilitate thermal contact between components in the device package 10 and between the device package 10 and the heat sink 22.

[0050] As heat flux density increases with increasing power density in advanced semiconductor devices, the cumulative thermal resistance of the system illustrated in FIG. 1 is increasingly problematic as heat cannot be dissipated quickly enough to allow semiconductor devices to run at optimal power. Consequently, the energy efficiency of semiconductor devices is reduced. Furthermore, heat is transferred between semiconductor devices within the device package 10, as shown with heat transfer path 24 (illustrated as a dashed line), where heat may be undesirably transferred from the first device 14 having a high heat flux, such as a central processing unit (CPU) or a graphical processing unit (GPU), to the device stack 15 having low heat flux, such as memory, through the heat spreader 18.

[0051] For example, as shown in FIG. 1, each device package component and the respective interfacial boundaries therebetween have a corresponding thermal resistance that forms heat transfer path 26 (illustrated by path 26 in FIG. 1). The right-hand side of FIG. 1 illustrates the heat transfer path 26 as a series of thermal resistances R1-R8 between a heat source and a heat sink. Here, R1 is the thermal resistance of the bulk semiconductor material of the first device 14. R3 and R7 are the thermal resistances of the first TIM layers 16A, 16B and the second TIM layer 20, respectively. R5 is the thermal resistance of the heat spreader 18. R2, R4, R6, and R8 represent the thermal resistance at the interfacial region of the components (e.g., contact resistances). In a typical cooling system, R3 and R7 may account for 80% or more of the cumulative thermal resistance of the heat transfer path 26, and R5 may account for 5% or more. R1 of the first device 14 and R2, R4, R6, and R8 of the interfaces account for the remaining cumulative thermal resistance. Accordingly, embodiments described herein provide for integrated cooling assemblies embedded within a device package. The embedded cooling assemblies shorten the thermal resistance path between a semiconductor device and a heat sink and reduce thermal communication between semiconductor devices disposed in the same device package, such as described in relation to the figures below.

[0052] FIG. 2A is a schematic plan view of an example of a system panel 100, in accordance with some embodiments of the present disclosure. Generally, the system panel 100 includes a printed circuit board (PCB) 102, a plurality of device packages 201 mounted to the PCB 102, and a plurality of coolant lines 108 fluidly coupling each of the device packages 201 to a coolant source 110. It is contemplated that coolant fluid may be delivered to each of the device packages 201 in any desired fluid phase (e.g., liquid, vapor, gas, or combinations thereof) and may flow out from each device package 201 in the same phase or a different phase. In some embodiments, the coolant fluid is delivered to the device packages 201 andreturned therefrom as a liquid, whereby the coolant source 110 may comprise a heat exchanger or chiller to maintain the coolant fluid at a desired temperature. In other embodiments, the coolant fluid may be delivered to the device packages 201 as a liquid, vaporized to a vapor within the device packages 201, and returned to the coolant source 110 as a vapor. In those embodiments, the device packages 201 may be fluidly coupled to the coolant source 110 in parallel, and the coolant source 110 may include or further include a compressor (not shown) for condensing the received vapor to a liquid form.

[0053] FIG. 2B is a schematic partial sectional side view of a portion of the system panel 100 of FIG. 2A, in accordance with some embodiments of the disclosure. As shown, each device package 201 is fluidly coupled to the plurality of coolant lines 108 and is disposed in a socket 114 of the PCB 102 and connected thereto using a plurality of pins 116, or by other suitable connection methods, such as solder bumps (not shown). The device package 201 may be seated in the socket 114 and secured to the PCB 102 using a mounting frame 106 and a plurality of fasteners 112, (e.g., compression screws, collectively configured to exert a relatively uniform downward force on the upward facing edges of the device package 201). The uniform downward force ensures proper pin contact between the device package 201 and the socket 114.

[0054] FIG. 2C is a schematic exploded isometric view of an example device package 201, in accordance with some embodiments of the present disclosure. Generally, the device package 201 includes a package substrate 202, an integrated cooling assembly 203 disposed on the package substrate 202, and a package cover 208 disposed on a peripheral portion of the package substrate 202. Suitable materials that may be used in the package cover 208 include copper, aluminum, metal alloys, plastics, etc. The package cover 208 extends over the integrated cooling assembly 203 so that the integrated cooling assembly 203 is disposed between the package substrate 202 and the package cover 208. The integrated cooling assembly 203 may include a semiconductor device 204 and a cold plate 206 bonded to the semiconductor device 204. In some embodiments, the cold plate 206 may comprise substrate material like silicon, glass, ceramic, etc. The integrated cooling assembly 203 may also include a manifold 224 attached to the cold plate 206. In some embodiments, the lateral dimensions, or footprint, of the cold plate 206 and / or the manifold 224 is the same size or larger than the lateral dimensions, or footprint, of the semiconductor device 204. In some embodiments, the footprint of the cold plate 206 and / or the manifold 224, as viewed from a top plan view, is the same size, or is larger than the footprint of the semiconductor device204, as viewed from a top plan view. In some embodiments, the footprint of the cold plate 206 and / or the manifold 224 may be larger or the same size in one or both directions when compared to the footprint of the semiconductor device 204.

[0055] The manifold 224, may comprise one or more portions (e.g., a first portion 260, a second portion 262, and a third portion 264 as shown in FIG. 3). In some embodiments, each portion of the manifold 224 comprises one or more coolant channels.

[0056] As shown, the device package 201 further includes a sealing material layer 222 that forms a coolant fluid impermeable barrier between the package cover 208 and the integrated cooling assembly 203 that prevents leaking of the coolant fluid outside of the cooling assembly and prevents coolant fluid from reaching an active side 218 (discussed below in relation to FIG. 3) of the semiconductor device 204 and causing damage thereto. In some embodiments, the sealing material layer 222 comprises an adhesive material that reliably attaches the package cover 208 to the integrated cooling assembly 203. In some embodiments, the sealing material layer 222 comprises a polymer or epoxy material that extends upwardly from the package substrate 202 to encapsulate and / or surround at least a portion of the semiconductor device 204. In some embodiments, the sealing material layer 222 may also comprise conductive material (e.g., solder). In other embodiments, the sealing material layer 222 is formed from a molding compound (e.g., a thermoset resin), that when polymerized, forms a hermetic seal between the package cover 208 and the cold plate 206. Here, the coolant fluid is delivered to the manifold 224 through openings 222A disposed through the sealing material layer 222. As shown, the openings 222A are respectively in registration and fluid communication with inlet and outlet openings 212 of the package cover 208 thereabove and inlet and outlet openings 224A in the manifold 224 therebelow. Coolant fluid may be delivered to the cold plate 206 through openings 224A disposed through the manifold 224. For example, the openings 224A may be respectively in registration and fluid communication with inlet and outlet openings 222A of the sealing material layer 222 thereabove and inlet and outlet openings (not shown) in the cold plate 206 therebelow. In some embodiments, the inlet and outlet openings in the cold plate 206 and / or the manifold 224 are outside of the footprint of the semiconductor device 204.

[0057] It will be understood that any of the openings described herein may have any cross-sectional shape that allows fluid to flow therethrough (e.g., rectangular, square, hexagonal or circular cross-sections). For example, the inlet and outlet openings 224A of the manifold 224 may form an elongated shape extending from one side of the manifold 224 to another side ofthe manifold 224. For example, the inlet and outlet openings 224A may form any shape having a length greater than a width in the X-Y plane (e.g., a rectangular or a trapezoidal shape). In some embodiments, the inlet and outlet openings of the cold plate 206 may form any shape, such as an elongated shape extending from one side of the cold plate 206 to another side of the cold plate 206. A shape in the X-Y plane of the openings 222A disposed through the sealing material layer 222 may be substantially the same as the shape of the inlet and outlet openings of the cold plate 206 and / or the inlet outlet openings 224A of the manifold 224 in the same place. In some embodiments, references to an opening throughout the present disclosure refer to an opening defined by a sidewall (e.g., opening sidewall).

[0058] Generally, the package substrate 202 includes a rigid material, such as an epoxy or resin-based laminate, that supports the integrated cooling assembly 203 and the package cover 208. The package substrate 202 may include conductive features disposed in or on the rigid material that electrically couples the integrated cooling assembly 203 to a system panel, such as the PCB 102.

[0059] FIG. 3 is a schematic sectional view in the X-Z plane of the device package 201 taken along line A- A’ of FIG. 2C, in accordance with some embodiments of the disclosure. As illustrated in FIG. 3, the semiconductor device 204 includes the active side 218 that includes device components (e.g., transistors, resistors, and capacitors, formed thereon or therein), and a non-active side, here the semiconductor device backside 220, opposite the active side 218. As shown, the active side 218 is facing towards an interposer 254 and the package substrate 202. In some embodiments, the interposer 254 is attached to the package substrate 202. The active side 218 may be electrically connected to the package substrate 202 by use of conductive bumps 219, which are encapsulated by a first underfill layer 221 disposed between the semiconductor device 204 and the package substrate 202. The first underfill layer 221 may comprise a cured polymer resin or epoxy, which provides mechanical support to the conductive bumps 219 and protects against thermal fatigue. In some embodiments, the active side 218 may be electrically connected to another package substrate, another active die, or another passive die (e.g., interposer 254) using hybrid bonding or conductive bumps 219. The cold plate 206 may be disposed above the package substrate 202 with the semiconductor device 204 disposed therebetween. For example, the semiconductor device 204 (and the first underfill layer 221) may be disposed between the cold plate 206 and the package substrate 202. In some embodiments, the cold plate 206 may be disposed directly on the package substrate 202 and / or on the interposer 254.

[0060] In some embodiments, the cold plate 206 comprises a top portion 234 and a perimeter sidewall 240 (e.g., a perimeter sidewall defining a perimeter of the cold plate 206). The perimeter sidewall 240 may extend downwardly from the top portion 234 to level of the backside 220 of the semiconductor device 204. In some embodiments, the top portion 234, the perimeter sidewall 240, and the backside 220 of the semiconductor device 204 collectively define a coolant channel therebetween. In some embodiments, the cold plate 206 also comprises cavity dividers extending downwardly from the top portion 234 towards the backside 220 of the semiconductor device 204. The cavity dividers may extend laterally and in parallel between an inlet opening of the cold plate 206 and an outlet opening of the cold plate 206 to define one or more coolant channels therebetween. In some embodiments, the cold plate 206 comprises one cavity divider which forms two coolant channels (e.g., one coolant channel on either side of the cavity divider) and portions of the perimeter sidewall 240. In some embodiments, one or more coolant channels of the cold plate 206 may be formed between a cavity divider and a portion of the perimeter sidewall 240 extending parallel to the cavity divider. Alternatively, in other embodiments, the cold plate 206 may comprise plural cavity dividers, for example two cavity dividers, five cavity dividers, or six cavity dividers. In such examples, the cold plate 206 comprises more than two coolant channels, for example three coolant channels, four coolant channels, nine coolant channels, or more, defined between the cavity divider(s) and the perimeter sidewall 240.

[0061] In some embodiments, cavity dividers comprise cavity sidewalls which form surfaces of the one or more coolant channels of the cold plate 206. In embodiments where plural cavity dividers extend in parallel to each other, cavity sidewalls of adjacent cavity dividers are opposite (e.g., facing) each other. In embodiments comprising a single cavity divider, a first cavity sidewall may be opposite (e.g., face) a first portion of the perimeter sidewall 240 extending parallel to and facing the first cavity sidewall. A second cavity sidewall may be opposite (e.g., face) a second portion of the perimeter sidewall 240 extending parallel to and facing the second cavity sidewall. The first portion of the perimeter sidewall 240 may be an opposite side of the cold plate 206 to the second portion of the perimeter sidewall 240. For example, in embodiments where the cold plate 206 is rectangular, first and second opposing sides of the rectangular cold plate 206 form the first and second portions of the perimeter sidewall 240.

[0062] In some embodiments, cavity dividers may be continuous cavity dividers which extend continuously (e.g., in the Y-axis direction) between the inlet opening and the outlet opening of the cold plate 206.

[0063] In some embodiments, the backside 220 of the semiconductor device 204 comprises a corrosion protective layer (not shown). The corrosion protective layer may be a continuous layer disposed across the entire backside 220 of the semiconductor device 204, such that the cold plate 206 is attached thereto. Beneficially, the corrosion protective layer provides a corrosion-resistant barrier layer, thus preventing undesired corrosion of the semiconductor device 204 (e.g., the semiconductor substrate material which might otherwise be in direct contact with coolant fluid flowing through one or more coolant channels of the cold plate 206.

[0064] The coolant channels may extend between a single inlet opening and a single outlet opening of the cold plate 206, such that the coolant channels share the same inlet and outlet openings. In some embodiments, multiple inlet and / or outlet openings may be coupled to the coolant channels.

[0065] In embodiments having plural coolant channels, each coolant channel may be connected between a separate inlet opening and a separate outlet opening. In such embodiments, the coolant fluid may be directed to the separate inlet openings and from the separate outlet openings using the manifold 224 disposed above the openings in the Z-axis direction.

[0066] In some embodiments, a height in the Z-axis direction of the coolant channels may be greater than 100 pm, 100 pm- 1000 pm, or 100 pm-700 pm. A width in the X-axis direction of the coolant channels may be greater than 100 pm, 100 pm-1000 pm, or 100 pm-700 pm. For example, the width of the coolant channels may be greater than the height. A crosssection of the coolant channels in the Y-Z plane is wide enough to allow for a pressure drop of 0-100 psi, 3-15 psi, or 4-10 psi.

[0067] In some embodiments, preparing a desired surface roughness of the sidewalls of the coolant channels may include depositing an organic layer on a photoresist layer after cold plate features have been etched to form a micro-masking layer, such as between 1 to 30 nm. The micro-masking layer may be dry etched to form the desired surface roughness, such as between 0.1 to 3.0 nm.

[0068] With reference to FIG. 3, the cold plate 206 is attached to the backside 220 of the device 204 without the use of an intervening adhesive. For example, the cold plate 206 maybe directly bonded to the backside 220 of the device 204, such that the cold plate 206 and the backside 220 of the device 204 are in direct contact. For example, in some embodiments, one or both of the cold plate 206 and the backside 220 of the semiconductor device 204 may comprise a dielectric material layer (e.g., a first dielectric material layer and a second dielectric material layer respectively), and the cold plate 206 is directly bonded to the backside 220 of the semiconductor device 204 through bonds formed between the dielectric material layers. In some embodiments, one of the cold plate 206 or the backside 220 of the semiconductor device 204 may comprise a thin bonding dielectric layer (e.g., silicon nitride, etc.) and other element(s) may not include any such explicit bonding dielectric layer (or can have only a native oxide layer). In some embodiments, one or more dielectric material layers are continuous layers. In some embodiments, one or more dielectric material layers may not be continuous. For example, a first dielectric material layer may be disposed only on lower surfaces of the cold plate 206 facing the backside 220 of the semiconductor device 204. In some embodiments, portions of a first dielectric material layer may be disposed only on lower surfaces of support features 230 and the perimeter sidewall 240. Beneficially, directly bonding the cold plate 206 to the semiconductor device 204, as described above, reduces the thermal resistance therebetween and increases the efficiency of heat transfer from the semiconductor device 204 to the cold plate 206. In some embodiments, thermal resistance is further reduced by directly bonding lower surfaces of cavity dividers facing the semiconductor device 204 to the backside 220 of the semiconductor device 204.

[0069] FIG. 4 is a schematic sectional view in the X-Z plane of a portion of the integrated cooling assembly 203, in accordance with some embodiments of the disclosure. In FIG. 4, the cold plate 206 comprises a patterned side that faces towards the semiconductor device 204 and an opposite side that faces towards the package cover 208 (not shown). The patterned side comprises one or more coolant channels 210, which extend laterally between the inlet and outlet openings of the cold plate 206. Each coolant channel 210 comprises cavity sidewalls that define a corresponding coolant channel 210. Portions of the cold plate 206 between the cavity sidewalls form support features 230. The support features 230 provide structural support to the integrated cooling assembly 203 and disrupt laminar fluid flow at the interface of the coolant and the device backside 220, resulting in increased heat transfer therebetween. Furthermore, by introducing plural coolant channels 210 to define separate coolant flow paths, an internal surface area of the cold plate 206 is increased, which further increases the efficiency of heat transfer.

[0070] In FIG. 4, arrows 228A and 228B illustrate two different heat transfer paths in the integrated cooling assembly 203. A first heat transfer path illustrated by arrow 228B shows heat generated by the semiconductor device 204 transferring directly from the semiconductor material of the semiconductor device 204 to coolant fluid flowing through the cold plate 206. A second heat transfer path illustrated by arrows 228A shows heat generated by the semiconductor device 204 being transferred from semiconductor material (e.g., silicon material) of the semiconductor device 204 to semiconductor material (e.g., silicon material) of the cold plate 206 structure, propagated throughout the semiconductor material of the cold plate 206 structure (shown as dashed lines), and being transferring into coolant fluid flowing through the cold plate 206. A thermal resistance of the first and second heat transfer paths 228A, 228B is illustrated by heat transfer path 228C, which is shown as thermal resistance R1 between a heat source and a cold plate. Here, R1 is the thermal resistance of the bulk semiconductor material of the semiconductor device 204. It can be seen that the heat transfer path 228C of the integrated cooling assembly 203 is reduced compared to the heat transfer path 26 of the device package 10 of FIG. 1, due to the direct bonding discussed above.

[0071] In some embodiments, the cold plate 206 may be attached to the semiconductor device 204 using a hybrid bonding technique, where bonds are formed between one or more dielectric material layers and between metal features, such as between first metal pads and second metal pads, disposed in the one or more dielectric material layers.

[0072] Suitable dielectrics that may be used as the one or more dielectric material layers include silicon oxides, silicon nitrides, silicon oxynitrides, silicon carbon nitrides, metal-oxides, metal-nitrides, silicon carbide, silicon oxycarbides, silicon oxycarbonitride, diamondlike carbon (DLC), or combinations thereof. In some embodiments, one or more of the dielectric material layers are formed of an inorganic dielectric material (e.g., a dielectric material substantially free of organic polymers). Typically, one or more of the dielectric layers are deposited to a thickness greater than the thickness of a native oxide, such as about 1 nanometer (nm) or more, 5nm or more, lOnm or more, 50nm or more, or lOOnm or more. In some embodiments, one or more of the dielectric layers are deposited to a thickness of 3 micrometers or less, 1 micrometer or less, 500nm or less, such as lOOnm or less, or 50nm or less. The dielectric layer material and thickness may be optimized for lower thermal resistance between the die and the cold plate.

[0073] The cold plate 206 may be formed of any suitable material that has sufficient structural strength to withstand the desired pressures of coolant flowing into the coolantchannel 210. For example, the cold plate 206 may be formed of semiconductor material like silicon or other engineered materials like glass. In other examples, the cold plate 206 may be formed of a material selected from a group comprising polymers, metals, ceramics, or composites thereof. In some embodiments, the cold plate 206 may be formed of stainless steel (e.g., from a stainless-steel metal sheet) or a sapphire plate.

[0074] In some embodiments, the cold plate 206 may be formed of a bulk material having a substantially similar coefficient of linear thermal expansion (CTE) to the bulk material of the substrate 202 and / or the semiconductor device 204, where the CTE is a fractional change in length of the material (in the X-Y plane) per degree of temperature change. In some embodiments, the CTEs of the cold plate 206, the substrate 202, and / or the semiconductor device 204 are matched so that the CTE of the substrate 202 and / or the semiconductor device 204 is within about + / - 20% or less of the CTE of the cold plate 206, such as within + / - 15% or less, within + / - 10% or less, or within about + / - 5% or less when measured across a desired temperature range. In some embodiments, the CTEs are matched across a temperature range from about -60°C to about 100°C or from about -60°C to about 175°C. In one example embodiment, the matched CTE materials each include silicon.

[0075] In some embodiments, the cold plate 206 may be formed of a material having a substantially different CTE from the semiconductor device 204 (e.g., a CTE mismatched material). In such embodiments, the cold plate 206 may be attached to the semiconductor device 204 by a compliant adhesive layer (not shown) or a molding material that absorbs the difference in expansion between the cold plate 206 and the semiconductor device 204 across repeated thermal cycles.

[0076] The package cover 208 shown in FIGS. 2C and 3 generally comprises one or more vertical or sloped sidewall portions 208A and a lateral portion 208B that spans and connects the sidewall portions 208A. The sidewall portions 208A may extend upwardly from a peripheral surface of the package substrate 202 to surround the device 204 and the cold plate 206 disposed thereon. The lateral portion 208B may be disposed over the cold plate 206 and is typically spaced apart from the cold plate 206 by a gap corresponding to the thickness of the sealing material layer 222. Coolant is circulated through the one or more coolant channel sthrough the inlet and outlet openings 212 of the package cover 208 formed through the lateral portion 208B. The inlet and outlet openings 224 A of the manifold 224 may be in fluid communication with the inlet and outlet openings 212 of the package cover 208 through the inlet and outlet openings 222A formed in the sealing material layer 222 disposedtherebetween. In certain embodiments, coolant lines 108 (FIGS. 2A-2B) may be attached to the device package 201 by use of connector features formed in the package cover 208, such as threads formed in the sidewalls of the inlet and outlet openings 212 of the package cover 208 and / or protruding features 214 that surround the inlet and outlet openings 212 and extend upwardly from a surface of the lateral portion 208B.

[0077] Typically, the package cover 208 is formed of semi-rigid or rigid material so that at least a portion of the downward force exerted on the package cover 208 by the mounting frame is transferred to a supporting surface of the package substrate 202 and not transferred to the cold plate 206 and the semiconductor device 204 therebelow. In some embodiments, the package cover 208 is formed of a thermally conductive metal, such as aluminum or copper. In such embodiments, the package cover 208 functions as a heat spreader that redistributes heat from one or more electronic components of the semiconductor device 204.

[0078] It should be noted that the direction in which the coolant fluid flows through the cold plate 206 may be controlled depending on the relative locations of the inlet and outlet openings. For example, the coolant fluid may flow from left to right in the device package 201 of FIG. 3 when the inlet openings 212, 222 A, 224 A of the package cover 208, the sealing material layer 222, and the manifold 224, respectively, are located on the left-hand side of the device package 201 the coolant may then flow through one or more inlet openings in the cold plate 206. The coolant may then exit the cold plate 206 through one or more outlet openings in the cold plate 206 and flow through outlet openings 212, 222 A, 224 A of the package cover 208, the sealing material layer 222, and the manifold 224, respectively, located on the righthand side of the device package 201. Alternatively, the coolant fluid may flow from right to left in the device package 201 illustrated in FIG. 3 when the outlet openings 212, 222 A, 224 A of the package cover 208, the sealing material layer 222, and the manifold 224 are located on the left-hand side of the device package 201 and the inlet openings 212, 222 A, 224 A of the package cover 208, the sealing material layer 222, and the manifold 224 are located on the right-hand side of the device package 201. Although only one set of inlet and outlet openings is shown and described here, additional inlet and outlet openings may also be provided at various locations on the package cover 208, the sealing material layer 222, and the manifold 224.

[0079] An example flow path of the coolant fluid through the one or more coolant channels may be as follows:1. Coolant fluid enters the one or more coolant channels of the manifold 224 through inlet openings.2. Coolant flows from the one or more coolant channels of the manifold 224 into one or more coolant channels of the cold plate 206. The one or more coolant channels of the manifold 224 may be formed to direct the coolant fluid from one or more inlet openings (e.g., opening 224A) to one or more inlet openings of the cold plate 206.3. Coolant fluid flows across the inside surfaces of the cold plate 206 and absorbs heat generated by the semiconductor device 204, which has dissipated into the cold plate 206 structure. The coolant fluid may also flow directly across the backside 220 of the semiconductor device 204 to absorb heat energy directly from the semiconductor device 204. The one or more coolant channels of the cold plate 206 may be formed to direct the coolant fluid from inlet opening(s) to outlet opening(s) and facilitate heat extraction from the semiconductor device 204 by the coolant fluid. In some embodiments, the coolant fluid may be in direct contact with the backside 220 of the semiconductor device 204 or via one or more substrate or layers between the coolant fluid or backside 220 of the semiconductor device 204.4. Coolant fluid exits the one or more coolant channels of the cold plate 206 through outlet openings of the cold plate 206. Coolant fluid enters the one or more coolant channels of the manifold 224 through the outlet openings of the cold plate 206. The one or more coolant channels of the manifold 224 may be formed to direct the coolant fluid from one or more outlet openings of the cold plate 206 to one or more outlet openings (e.g., opening 224A).5. Coolant fluid exits the one or more channels of the manifold 224 through outlet openings.

[0080] It will be understood from the above flow path that heat is extracted without introducing an unnecessary thermal resistance (e.g., a TIM disposed between the backside 220 of the semiconductor device 204 and the cold plate 206) between the backside 220 of the semiconductor device 204 and the cold plate 206.

[0081] FIG. 5 is a schematic side sectional view in the X-Z plane of an example of a multicomponent device package 501 that includes a cold plate 506 directly bonded to the backside surfaces of two or more devices 501 A, 501B. The multi-component device package 501 may be similar to the device package 201 described above, and therefore the description of similar features is omitted for brevity. In some embodiments, the two or more devices 501 A and50 IB are reconstituted and then bonded to the cold plate 506. As shown, the device package 501 includes a package substrate 502, an integrated cooling assembly 503 and a package cover 508.

[0082] The integrated cooling assembly 503 may include a plurality of devices 501 A (one shown), that may be singulated and / or disposed in a vertical device stack (e.g., device stack 50 IB). The cold plate 506 may be attached to each of the devices 501 A and device stack 501B (e.g., by the direct bonding methods described herein or other methods including flip chip bonding, etc.). In some embodiments, the device 501 A may comprise a processor and the device stack 501B may comprise a plurality of memory devices. Here, the device 501 A and the device stack 501B are disposed in a side-by-side arrangement on an interposer 554 attached to the package substrate 502. The device 501 A and the device stack 501B may be in electrical communication with one another through conductive elements formed in, on, or through the interposer 554. Here, the cold plate 506 is sized to provide a bonding surface for attachment to both the device 501 A and the device stack 501B but may otherwise be the same or substantially similar to other cold plates described herein.

[0083] In some embodiments, the lateral dimensions (or footprint) of the cold plate 506 may be the same or larger than the combined lateral dimensions (or footprint) of both the device 501 A and the device stack 501B. In some embodiments, one or more sidewalls of the cold plate 506 may extend past the vertical sidewalls of the device 501 A and the device stack 501B. In some embodiments, more than one cold plate 506 may be bonded. For example, separate cold plates may be bonded to the device 501 A and the device stack 501B. In some embodiments, the footprint of the cold plate 506 may be larger or the same size in one or both directions when compared to the combined footprint of both the device 501 A and the device stack 50 IB. In some embodiments, the inlet and outlet openings in the cold plate are outside of the footprints of both the device 501 A and the device stack 50 IB.

[0084] FIG. 6 is a flow diagram showing a method 60 of forming an integrated cooling assembly, according to embodiments of the present disclosure. Generally, the method 60 includes bonding a first substrate comprising one or more cold plates 206 to a second substrate comprising one or more semiconductor devices 204, and singulating one or more integrated cooling assemblies 203 from the bonded first and second substrates. For example, a wafer (bare or reconstituted wafer) comprising one or more cold plates 206 can be directly bonded to another wafer (bare or reconstituted wafer) comprising one or more semiconductor devices 204.

[0085] It will be understood that the first substrate may be a cold plate die or part of a wafer of cold plates. Further, the second substrate may be a semiconductor device die or part of a wafer of semiconductor devices 204. Therefore, the method 60 may include die-to-die direct bonding (e.g., cold plate die to semiconductor device die), water-to-die direct bonding (e.g., cold plate die to semiconductor device wafer, or cold plate wafer to semiconductor device die), and wafer-to-wafer direct bonding (e.g., cold plate wafer to semiconductor device wafer). It will be understood that the singulation step (discussed in relation to block 64, below) may not be required for a die-to-die direct bonding operation.

[0086] For simplicity, the following description is focused on forming one integrated cooling assembly 203 comprising one cold plate 206 and one semiconductor device 204. However, as mentioned above, in some embodiments, the first substrate may comprise plural cold plates 206 and the second substrate may comprise plural semiconductor devices 204, such that plural integrated cooling assemblies 203 may be formed from the first and second substrates.

[0087] At block 62, the method 60 includes directly bonding the first substrate (e.g., a monocrystalline silicon wafer) comprising a cold plate 206 to the second substrate (e.g., a monocrystalline silicon wafer) comprising a semiconductor device 204 without an intervening adhesive. In some embodiments, the cold plate 206 may be directly bonded to the backside of the semiconductor device 204.

[0088] In some embodiments, the first substrate may be etched using a patterned mask layer formed on its surface to form features of the cold plate 206. An anisotropic etch process may be used, which uses inherently differing etch rates for the silicon material as between {100} plane surfaces and {111} plane surfaces when exposed to an anisotropic etchant.

[0089] In some embodiments, the etching process is controlled to where the etch rates of the substrate surfaces have a ratio between about 1:10 and about 1 :200, such as between about 1:10 and about 1 : 100, for example between about 1:10 and 1:50, or between about 1 :25 and 1:75. Examples of suitable anisotropic wet etchants include aqueous solutions of potassium hydroxide (KOH), ethylene diamine and pyrocatechol (EPD), ammonium hydroxide (HN4OH), hydrazine (N2H4), or tetra methyl ammonium hydroxide (TMAH). The actual etch rates of the silicon substrate depend on the concentration of the etchant in the aqueous solution, the temperature of the aqueous solution, and a concentration of the dopant in the substrate (if any). Typically, the mask layer is formed of a material that is selective to anisotropic etch compared to the underlying monocrystalline silicon substrate. Examples ofsuitable mask materials include silicon oxide (SixOy) or silicon nitride (SixNy). In some embodiments, the mask layer has a thickness of about 100 nm or less, such as about 50 nm or less, or about 30 nm or less. The mask layer may be patterned using any suitable combination of lithography and material etching patterning methods.

[0090] The second substrate may include a bulk material, and a plurality of material layers disposed on the bulk material. The bulk material may include any semiconductor material suitable for manufacturing semiconductor devices, such as silicon, silicon carbide, silicon germanium, germanium, group III-V semiconductor materials, group II- VI semiconductor materials, or combinations thereof. While some high-performance processors like CPUs, GPUs, neural processing units (NPUs), and tensor processing units (TPUs) are typically made out of silicon, some other high-power density (hence substantial heat-generating) devices may comprise silicon carbide or gallium nitride, for example. In some embodiments, the second substrate may include a monocrystalline wafer, such as a silicon wafer, a plurality of device components formed in or on the silicon wafer, and a plurality of interconnect layers formed over the plurality of device components. In other embodiments, the second substrate may comprise a reconstituted substrate (e.g., a substrate formed from a plurality of singulated devices embedded in a support material). In some embodiments, each semiconductor device may have its own individual cold plate fabricated through a reconstitution process.

[0091] The bulk material of the second substrate may be thinned after the semiconductor device 204 is formed using one or more backgrinding, etching, and polishing operations that remove material from the backside. Thinning the second substrate may include using a combination of grinding and etching processes to reduce the thickness (in the Z-direction) to about 450 pm or less, such as about 200 pm or less, or about 150 pm or less or about 50 pm or less. After thinning, the backside 220 may be polished to a desired smoothness using a chemical mechanical polishing (CMP) process, and the dielectric material layer may be deposited thereon. In some embodiments, the dielectric material layer may be polished to a desired smoothness to prepare the second substrate for the bonding process. In some embodiments, the method 60 includes forming a plurality of metal features in the dielectric material layer in preparation for a hybrid bonding process, such as by use of a damascene process.

[0092] In some embodiments, the active side of the second substrate is temporarily bonded to a carrier substrate (not shown) before or after the thinning process. When used, the carrier substrate provides support for the thinning operation and / or for the thinned material tofacilitate substrate handling during one or more of the subsequent manufacturing operations described herein.

[0093] Here, the method 60 may include forming dielectric layers on one or both the first and second substrates, and directly bonding includes forming dielectric bonds between a first dielectric material layer of the first substrate and a second dielectric material layer of the second substrate (or forming dielectric bonds between one substrate and a dielectric material layer of the other substrate). Direct bonding processes join dielectric layers by forming strong chemical bonds (e.g., covalent bonds) between the dielectric layers.

[0094] Generally, directly bonding the surfaces (of the dielectric material layers formed on the first and second substrates) includes preparing, aligning, and contacting the surfaces. Examples of dielectric material layers include silicon oxide, silicon nitride, silicon oxynitride, and silicon carbonitride. Preparing the surfaces may include smoothing the respective surfaces to a desired surface roughness, such as between 0.1 to 3.0 nm RMS, activating the surfaces to weaken or open chemical bonds in the dielectric material, and terminating the surfaces with a desired species. Smoothing the surfaces may include polishing the first and second substrates using a CMP process. Activating and terminating the surfaces with a desired species may include exposing the surfaces to radical species formed in a plasma. The bond interface between the bonded dielectric layers can include a higher concentration of materials from the activation and / or last chemical treatment processes compared to the bulk of the bonding layers. For example, in some embodiments that utilize a nitrogen plasma for activation, a nitrogen concentration peak can be formed at the bond interface. In some embodiments, the nitrogen concentration peak may be detectable using secondary ion mass spectroscopy (SIMS) techniques. In various embodiments, for example, a nitrogen termination treatment (e.g., exposing the bonding surface to a nitrogen-containing plasma) can replace OH groups of a hydrolyzed (OH-terminated) surface with NH2 molecules, yielding a nitrogen-terminated surface. In embodiments that utilize an oxygen plasma for activation, an oxygen concentration peak can be formed at the bond interface between non-conductive bonding surfaces.

[0095] In some embodiments, the plasma is formed using a nitrogen-containing gas (e.g., N2), and the terminating species includes nitrogen, or nitrogen and hydrogen. In some embodiments, fluorine may also be present within the plasma. In some embodiments, the surfaces may be activated using a wet cleaning process (e.g., by exposing the surfaces to an aqueous ammonia solution). In some embodiments, the dielectric bonds may be formedusing a dielectric material layer deposited on only one of the first and second substrates, but not on both. In those embodiments, the direct dielectric bonds may be formed by contacting the deposited dielectric material layer of one of the first and second substrates directly with a bulk material surface (or such a surface with a native oxide) of the other substrate.

[0096] Directly forming direct dielectric bonds between the first and second substrates at block 62 may include bringing the prepared and aligned surfaces into direct contact at a temperature less than 150°C, such as less than 100°C, for example, less than 30°C, or about room temperature, e.g., between 20°C and 30°C. Without intending to be bound by theory, in the case of directly bonding surfaces terminated with nitrogen and hydrogen (e.g., NH2 groups), it is believed that the hydrogen terminating species diffuse from the interfacial bonding surfaces, and chemical bonds are formed between the remaining nitrogen species during the direct bonding process. In some embodiments, the direct bond is strengthened using an anneal process, where the substrates are heated to and maintained at a temperature of greater than about 30°C and less than about 450°C, for example, greater than about 50°C and less than about 250°C, or about 150°C, for a duration of about 5 minutes or more, such as about 15 minutes. Typically, the bonds will strengthen over time even without the application of heat. Thus, in some embodiments, the method does not include heating the substrates.

[0097] In embodiments where the first and second substrates are bonded using hybrid dielectric and metal bonds, the method 60 may further include planarizing or recessing the metal features below the dielectric field surface before contacting and bonding the dielectric material layers. After the dielectric bonds are formed, the first and second substrates may be heated to a temperature of 150°C or more and maintained at the elevated temperature for a duration of about 1 hour or more (e.g., between 8 and 24 hours) to form direct metallurgical bonds between the metal features.

[0098] Suitable direct dielectric and hybrid bonding technologies that may be used to perform aspects of the methods described herein include ZiBond® and DBI®, each of which are commercially available from Adeia Holding Corp., San Jose, CA, USA.

[0099] At block 64, the method 60 includes singulating at least one integrated cooling assembly 203 from the bonded first and second substrates. Singulation after bonding may impart distinctive structural characteristics on the integrated cooling assembly 203 as the bonding surface of the cold plate 206 may have a different perimeter than the backside of the semiconductor device 204 bonded thereto. In some embodiments, the sidewalls (e.g., sidesurfaces) of the cold plate 206 may extend past the edges (e.g., side surfaces) of the semiconductor device 204. In some embodiments, the cold plate 206 is singulated from the first substrate using a process that cuts or divides the first substrate in a vertical plane (i.e., in the Z-direction). In those embodiments, the side surfaces of the cold plate 206 are substantially perpendicular to the backside 220 of the semiconductor device 204 (i.e., a horizontal (X-Y) plane of an attachment interface between the semiconductor device 204 and the cold plate 206). In some embodiments, the cold plate 206 is singulated using a saw or laser dicing process.

[0100] At block 66, the method 60 may include connecting the integrated cooling assembly 203 to the package substrate 202 and sealing a package cover 208 comprising inlet and outlet openings 212 to the integrated cooling assembly 203 by use of a molding compound that, when cured, forms a sealing material layer 222.

[0101] At block 68, the method 60 may include, before or after sealing the package cover 208 to the integrated cooling assembly 203, forming inlet and outlet openings 222 A in the sealing material layer 222 to fluidly connect the inlet and outlet openings 212 of the package cover 208 to the manifold 224 and cold plate 206.

[0102] Demand for high performance computing (HPC) caused size of processor and HBM chip to grow, and the size of the interposer has grown accordingly. Power densities in HPC may be growing from 0.8 W / mm2to 2 W / mm2, 4 W / mm2, and 7 W / mm2. IC design may have moved away from a conventional approach of minimizing high current density areas known as hot spots. Accordingly, there is a need to mitigate hot spots and non-uniform heat maps.

[0103] Embodiments herein may provide for a cooling system that provides compatibility with pressure drop of datacenter facilities (e.g., mitigate pressure drop) and reduction of hot spots and non-uniform heat maps on chips. Embodiments may provide for a system design that uses a low thermal resistance, highly efficient cold plate, where IC processor and HBM layout enables for significant improvement in thermal management over conventional HPC modules. Advantageously, embodiments of the present disclosure provide a system that may use current infrastructure to be easily implemented.

[0104] In some embodiments, the system is designed to mitigate, reduce, or minimize the pressure drop. Pressure drop of the coolant may lead to increased pump energy consumption, reduced coolant flow rates, and / or uneven thermal dissipation across the semiconductor device. These inefficiencies can degrade the overall cooling performance, leading to thermalhotspots that adversely affect the semiconductor’s longevity and operation stability.Accordingly, there exists a need for improved energy-efficient cooling systems with reduced pressure drop.

[0105] In some embodiments, the semiconductor device may be partitioned into regions, and a uniform flow rate may be determined. The uniform flow rate may be a lowest flow rate for cooling or a flow rate used to take the heat away or maintain a temperature requirement for the semiconductor device (e.g., less than about 90 degrees C, 85 degrees C, etc.). The uniform flow rate may be a minimum amount of flow to everywhere in the system. Reducing the flow rate may reduce the pressure drop. In some embodiments, the system may be designed by taking into consideration hot spot region(s) and non-hot spot region(s) to reduce the flow rate.

[0106] In some embodiments, a cold plate and / or manifold is designed to increase thermal dissipation related to one or more hot spots, balance the coolant flow throughout the cold plate, and / or manipulate pressure drop. In some embodiments, one or more cold plates and / or one or more manifolds are designed as described in U.S. Patent Application Number 19 / 003,731, the entire disclosure of which is hereby incorporated by reference herein.

[0107] In some embodiments, the cold plate and / or manifold may comprise one or more coolant channels with different cross-sectional areas. Coolant channels with larger cross-sectional areas may be used to reduce the pressure drop and / or increase coolant flow in one or more portions of the cold plate. Coolant channels with smaller cross-sectional areas may be used to increase the pressure drop and / or decrease coolant flow in one or more portions of the cold plate. A combination of cross-sectional areas (e.g., a first plurality of coolant channels with a first cross-sectional area and a second plurality of coolant channels with a second cross-sectional area smaller than the first cross-sectional area) may be used to balance the coolant flow for optimal cooling.

[0108] In another example, the cold plate and / or manifold may comprise one or more coolant channels with different lengths. Coolant channels with shorter lengths may be used to reduce the pressure drop. Coolant channels with longer lengths may be used to increase the pressure drop. A combination of coolant channel lengths (e.g., a first plurality of coolant channels with a first length and a second plurality of coolant channels with a second length smaller than the first length) may be used to achieve the desired pressure drop and / or balance the coolant flow for optimal cooling. In some embodiments, additional inlets and / or outlets areadded to shorten the lengths of the coolant channels. Shortening the lengths of the coolant channels may result in reducing pressure drop and / or balancing the coolant flow.

[0109] In another example, the cold plate and / or manifold may comprise different numbers of coolant channels in different areas of the cold plate and / or manifold. For example, a manifold may comprise a first number (e.g., seven) of coolant channels within a first portion of the manifold and a second number (e.g., fourteen) of coolant channels within a second portion of the manifold, wherein the first portion of the manifold and the second portion of the manifold have the same footprint. Having a larger number of coolant channels within the first portion of the manifold can be used to reduce the pressure drop and / or increase coolant flow. Having a lesser number of coolant channels within the second portion of the manifold can be used to increase the pressure drop, decrease coolant flow in one or more portions of the cold plate, and / or balance the coolant flow for optimal cooling.

[0110] In another example, the cold plate and / or manifold may comprise different densities of coolant channels in different areas of the cold plate and / or manifold. For example, a manifold may comprise a first distance between adjacent coolant channels within a first portion of the manifold and a second distance between adjacent coolant channels within a second portion of the manifold, wherein the first distance is less than the second distance. Having a higher density (e.g., smaller distance between adjacent coolant channels) of coolant channels can result in increased coolant flow across the first portion of the manifold compared to the second portion of the manifold comprising the lower density (e.g., larger distance between adjacent coolant channels).

[0111] In another example, the cold plate and / or manifold may comprise one or more inlets and / or outlets with different cross-sectional areas. Inlets and / or outlets with larger cross-sectional areas may be used to reduce the pressure drop and / or increase coolant flow in one or more portions of the cold plate and / or manifold. Inlets and / or outlets with smaller cross-sectional areas may be used to increase the pressure drop and / or decrease coolant flow in one or more portions of the cold plate and / or manifold. A combination of cross-sectional areas (e.g., a first outlet with a first cross-sectional area and a second outlet with a second cross-sectional area smaller than the first cross-sectional area) may be used to reduce the pressure drop and / or balance the coolant flow for optimal cooling.

[0112] In some embodiments, a manifold may enable distribution of coolant from a single supply line (e.g., single inlet) into multiple separate coolant supply lines (e.g., multiple subinlets), and from multiple separate coolant outlet lines (e.g., multiple sub-outlets) into a singlecoolant outlet line (e.g., single outlet). A manifold may have a single inlet and outlet.Coolant may come in through the inlet of a manifold, and be distributed to or to feed multiple coolant channels to be coupled to multiple inlets of a cold plate. A cold plate may have multiple outlets to be coupled to or to drain to multiple outlet lines of the manifold and combined to a single outlet of the manifold.

[0113] FIG. 7 illustrates portions of a manifold, in accordance with some embodiments of the present disclosure. In some embodiments, a manifold comprises a first portion 702, a second portion 704, and a third portion 706. Although three portions are shown, any number of portions may be used. The portions of the manifold may comprise one or more metals (e.g., copper) and / or plastics (e.g., polyetherimide (PEI), polyether ether ketone (PEEK), polycarbonate, etc.). In some embodiments, the portions of the manifold all comprise the same material. In some embodiments, different portions of the manifold comprise different materials to facilitate heat spreading. For example, the first portion 702 may comprise a plastic while the third portion 706 may comprise a metal (e.g., copper, aluminum, etc.). The third portion 706 may comprise the metal because the third portion 706 is closest to the cold plate. Accordingly, the metal may be better at dispersing heat away from the cold plate compared to a plastic material. In some embodiments, one or more portions of the manifold may be coated with a material to prevent corrosion. For example, if the third portion 706 comprises copper then the third portion 706 may be coated with nickel. In some embodiments, one or more portions of the manifold may be anodized. For example, the third portion 706 may comprise aluminum and the surface of the third portion 706 may be anodized.

[0114] The three portions may be combined to create a manifold. For example, the second portion 704 may be attached to the third portion 706. The first portion 702 may then be attached to the second portion 704 and the third portion 706. In another example, the first portion 702 may first be attached to the second portion 704. The third portion 706 may then be attached to the second portion 704 and the first portion 702.

[0115] In some embodiments, one or more portions of the manifold are attached using one or more adhesives (epoxy, glue, room temperature vulcanizing (RTV), and / or similar such adhesives). In some embodiments, one or more portions of the manifold are attached using O-rings, gaskets, screws, bolts, and / or similar such parts.

[0116] In some embodiments, each portion of the manifold may have a first face and a second face opposite of the first face. For simplicity, the top face of each portion is the facethat is upright in FIG. 7, and the bottom face of each portion is the face that is facing down (not shown) in FIG. 7. In some embodiments, the top face of the second portion 704 is attached to the top face of the third portion 706. Then the top face of the first portion 702 is attached to the bottom face of the second portion 704.

[0117] The first portion 702 of the manifold may comprise one or more coolant channels. For example, the first portion 702 may comprise a first coolant channel 708 and a second coolant channel 710. The first coolant channel 708 may comprise a first opening 712 to couple with a first coolant line. The second coolant channel 710 may comprise a second opening 714 to couple with a second coolant line. In some embodiments, coolant enters the manifold by flowing from the first coolant line into the first coolant channel 708 via the first opening 712. In some embodiments, coolant exits the manifold by flowing from the second coolant channel 710 into the second coolant line via the second opening 714.

[0118] The second portion 704 may also comprise one or more coolant channels. For example, the second portion 704 may comprise a third coolant channel 716 and a first plurality of outlet coolant channels 718a-f. Although six outlet coolant channels are shown more or less coolant channels may be used. In some embodiments, the third coolant channel 716 is coupled with the first coolant channel 708 so that coolant can flow from the first coolant channel 708 into the third coolant channel 716. In some embodiments, the first plurality of outlet coolant channels 718a-f are coupled with the second coolant channel 710 so that coolant can flow from the first plurality of outlet coolant channels 718a-f into the second coolant channel 710.

[0119] The third portion 706 may also comprise one or more coolant channels. For example, the third portion 706 may comprise a fourth coolant channel 720 and a second plurality of outlet coolant channels 722a-f. Although six outlet coolant channels are shown more or less coolant channels may be used. In some embodiments, the third portion 706 has the same number of outlet coolant channels as the second portion 704. In some embodiments, the fourth coolant channel 720 is coupled with the third coolant channel 716 so that coolant can flow from the third coolant channel 716 into the fourth coolant channel 720. In some embodiments, the second plurality of outlet coolant channels 722a-f are coupled with the first plurality of outlet coolant channels 718a-f so that coolant can flow from the second plurality of outlet coolant channels 722a-f into the first plurality of outlet coolant channels 718a-f.

[0120] In some embodiments, the third portion 706 may be directly coupled to a cold plate. One or more coolant channels of the third portion 706 may be fluidly connected to one ormore coolant channels of the cold plate. For example, the fourth coolant channel 720 is coupled with an inlet to a coolant channel of the cold plate so that coolant can flow from the fourth coolant channel 720 into the coolant channel of the cold plate. In another example, the second plurality of outlet coolant channels 722a-f are coupled with one or more coolant channels of the cold plate so that coolant can flow from the one or more coolant channels of the cold plate into the second plurality of outlet coolant channels 722a-f.

[0121] In some embodiments, the size of the coolant channel that supplies coolant to one or more outlets is larger than the size of the one or more outlets. This may reduce pressure drop across the system.

[0122] The portions of the manifold may direct coolant to and from a cold plate. For example, coolant may enter the first portion 702 of the manifold by flowing from a first coolant line into the first coolant channel 708 via the first opening 712. The coolant may then flow from the first coolant channel 708 into the third coolant channel 716 of the second portion 704 of the manifold. The coolant may then flow from the third coolant channel 716 into the fourth coolant channel 720 of the third portion 706 of the manifold. The coolant may then flow from the fourth coolant channel 720 into one or more coolant channels of the cold plate. The coolant then flows across the inside surfaces of the cold plate and absorbs heat generated by one or more semiconductor devices, which has dissipated into the cold plate structure. The coolant may also flow directly across the backside of the one or more semiconductor devices to absorb heat energy directly from the one or more semiconductor devices. The one or more coolant channels of the cold plate may be formed to direct the coolant fluid from inlet opening(s) of the cold plate to outlet opening(s) of the cold plate. The coolant then flows from the outlet of the one or more coolant channels of the cold plate into the second plurality of outlet coolant channels 722a-f of the third portion 706 of the manifold. The coolant then flows from the second plurality of outlet coolant channels 722a-f into the first plurality of outlet coolant channels 718a-f of the second portion 704 of the manifold. The coolant then flows from the first plurality of outlet coolant channels 718a-f into the second coolant channel 710 of the first portion 702 of the manifold. The coolant may then exit the manifold by flowing from the second coolant channel 710 of the first portion 702 of the manifold into a second coolant line via the second opening 714.

[0123] In some embodiments, the first portion 702 of the manifold and / or the third portion 706 of the manifold have a thickness between .25 inches and 2 inches. For example, the first portion 702 of the manifold and / or the third portion 706 of the manifold may a thickness of .5inches. In some embodiments, the thickness of the first portion 702 of the manifold is the same or similar to the thickness of the third portion 706 of the manifold. In some embodiments, the thickness of the first portion 702 of the manifold is different than the thickness of the third portion 706 of the manifold. In some embodiments, the second portion 704 of the manifold has a thickness between .05 inches and .5 inches. For example, the second portion 704 of the manifold may have a thickness of .125 inches.

[0124] FIG. 8 A shows a bottom view of a portion of a manifold, in accordance with some embodiments of the present disclosure. In some embodiments, FIG. 8A shows the bottom face 802 of the third portion 706 of the manifold displayed in FIG. 7. The third portion 706 may comprise a plurality of slots. For example, the third portion 706 may comprise a first slot 804, a second slot 806, a third slot 808, a fourth slot 810, and a fifth slot 812. Although five slots are shown, any number of slots may be used.

[0125] In some embodiments, the slots are coupled to one or more cold plates to allow coolant to flow between the third portion 706 of the manifold and the cold plate. One or more slots may comprise inlets that allow coolant to flow from the third portion 706 of the manifold into the cold plate. For example, the second slot 806 may comprise a first inlet 814 and the fourth slot 810 may comprise a second inlet 816. Coolant may flow from the inlets into the cold plate. For example, coolant may flow from the fourth coolant channel 720 of the third portion 706 of the manifold, through the first inlet 814 and the second inlet 816, into the cold plate. In some embodiments, the size of the coolant channel that supplies coolant to one or more inlets is larger than the size of the one or more inlets. This may reduce pressure drop across the system.

[0126] One or more slots may comprise outlets that allow coolant to flow from the cold plate into the third portion 706 of the manifold. For example, the first slot 804 may comprise a first outlet 818 and a second outlet 820, the third slot 808 may comprise a third outlet 822 and a fourth outlet 824, and the fifth slot 812 may comprise a fifth outlet 826 and a sixth outlet 828. Coolant may flow from the cold plate into the outlets. For example, coolant may flow from the cold plate, through the first outlet 818, into a third outlet channel 722c of the second plurality of outlet channels 722a-f of the third portion 706 of the manifold. In another example, coolant may flow from the cold plate, through the fourth outlet 824, into a fifth outlet channel 722e of the second plurality of outlet channels 722a-f of the third portion 706 of the manifold. In another example, coolant may flow from the cold plate, through the fifthoutlet 826, into a first outlet channel 722a of the second plurality of out channels 722 of the third portion 706 of the manifold.

[0127] In some embodiments, the inlets are the same shape. In some embodiments, the inlets are different shapes. In some embodiments, the inlets all have the same width, length, and / or height. In some embodiments, the inlets have different widths, lengths, and / or heights. In some embodiments, the widths of one or more inlets range from .3 inches to 1 inch. For example, the first inlet 814 may have a width of .5 inches. In some embodiments, the outlets are the same shape. In some embodiments, the outlets are different shapes. In some embodiments, the outlets all have the same width, length, and / or height. In some embodiments, the outlets have different widths, lengths, and / or heights. In some embodiments, the widths of one or more outlets range from .2 inches to .75 inches. For example, the first outlet 818 may have a width of .375 inches. In some embodiments, the inlets are the same shape as the outlets. In some embodiments, the inlets are different shapes than the outlets. In some embodiments, the inlets and outlets all have the same width, length, and / or height. In some embodiments, the inlets and outlets have different widths, lengths, and / or heights.

[0128] FIG. 8B shows a top view of a portion of a manifold, in accordance with some embodiments of the present disclosure. In some embodiments, FIG. 8B shows the bottom face 852 of the first portion 702 of the manifold displayed in FIG. 7. As described above, the first portion 702 of the manifold comprises the first coolant channel 708, the second coolant channel 710, the first opening 712, and the second opening 714. The first opening 712 may be couple with a first coolant line. The second opening 714 may be couple with a second coolant line. In some embodiments, coolant enters the first portion 702 of the manifold by flowing from the first coolant line into the first coolant channel 708 via the first opening 712. In some embodiments, coolant exits the manifold by flowing from the second coolant channel 710 into the second coolant line via the second opening 714.

[0129] FIG. 9 A shows a bottom view of a manifold 901, in accordance with some embodiments of the present disclosure. In some embodiments, the manifold 901 displayed in FIG. 9A comprises the three portions described in FIG. 7. In some embodiments, the manifold 901 is assembled by combining one or more portions. For example, the first portion 702, the second portion 704, and / or the third portion 706 are attached using one or more adhesives (epoxy, glue, RTV, and / or similar such adhesives). In another example, the first portion 702, the second portion 704, and / or the third portion 706 are attached using O-rings,gaskets, screws, bolts, and / or similar such parts. In some embodiments, the manifold 901 is made of a single piece. For example, the manifold 901 may be 3D printed. In some embodiments, the manifold 901 is attached to one or more cold plates using any of the methodologies described herein. FIG. 9B shows a top view of the manifold 901, in accordance with some embodiments of the present disclosure. In some embodiments, the manifold 901 displayed in FIG. 9B comprises the three portions described in FIG. 7 above.

[0130] FIG. 10 illustrates a plurality of coolant channels within a manifold, in accordance with some embodiments of the present disclosure. In some embodiments, FIG. 10 displays a plurality of coolant paths. The coolant paths may represent the paths where coolant flows as the coolant travels within a manifold (e.g., manifold 901). For example, the coolant paths may illustrate the path of coolant as it flows through a first portion (e.g., first portion 702), a second portion (e.g., second portion 704), and / or a third portion (e.g., third portion 706) of a manifold (e.g., manifold 901).

[0131] A first plurality of coolant paths 1002 may correspond to the flow of coolant from one or more coolant lines to a cold plate 1004. For example, coolant may flow from a coolant line through an inlet 1008 into a first portion of a manifold. The coolant many then flow from the first portion of the manifold into a second portion of the manifold. The coolant many then flow from the second portion of the manifold into a third portion of the manifold. The coolant may then flow from the third portion of the manifold into the cold plate 1004.

[0132] A second plurality of coolant paths 1006 may correspond to the flow of coolant from the cold plate 1004 to one or more coolant lines. For example, coolant may flow from the cold plate 1004 into a third portion of a manifold. The coolant many then flow from the third portion of the manifold into a second portion of the manifold. The coolant many then flow from the second portion of the manifold into a first portion of the manifold. The coolant may then flow from the first portion of the manifold into one or more coolant lines via an outlet 1010.

[0133] FIG. 11 illustrates a plurality of coolant channels within a manifold, in accordance with some embodiments of the present disclosure. In some embodiments, FIG. 11 displays a plurality of coolant paths between one or more coolant lines and a cold plate 1004. The coolant paths may represent the paths where coolant flows as the coolant travels within a manifold (e.g., manifold 901). For example, the coolant paths may illustrate the path of coolant as it flows through a first portion (e.g., first portion 702), a second portion (e.g., second portion 704), and / or a third portion (e.g., third portion 706) of a manifold (e.g.,manifold 901). The first plurality of coolant paths 1002 may correspond to the flow of coolant from one or more coolant lines to a cold plate 1004.

[0134] FIG. 12 illustrates a plurality of coolant channels within a manifold, in accordance with some embodiments of the present disclosure. In some embodiments, FIG. 12 displays a plurality of coolant paths between the cold plate 1004 and one or more coolant lines. The coolant paths may represent the paths where coolant flows as the coolant travels within a manifold (e.g., manifold 901). For example, the coolant paths may illustrate the path of coolant as it flows through a first portion (e.g., first portion 702), a second portion (e.g., second portion 704), and / or a third portion (e.g., third portion 706) of a manifold (e.g., manifold 901). The second plurality of coolant paths 1006 may correspond to the flow of coolant from the cold plate 1004 to one or more coolant lines.

[0135] FIG. 13 is a schematic sectional view of an example device package that may be used with the system panel, in accordance with some embodiments of the present disclosure. In some embodiments, FIG. 13 shows a portion of a manifold 1301. The manifold 1301 may comprise a first portion 1302, a second portion 1304, and a third portion 1306. Although three portions are shown, any number of portions may be used. The manifold 1301 may be attached to a cold plate 1308. The cold plate 1308 may be attached to a semiconductor device 1310. Although one manifold, one cold plate, and one semiconductor device are shown, a device package may comprise more manifolds, cold plates, and / or semiconductor devices.

[0136] The first portion 1302 of the manifold 1301, the second portion 1304 of the manifold 1301, and / or the third portion 1306 of the manifold 1301 may comprise one or more coolant channels. For example, the first portion 1302 may comprise a first coolant channel 1312, the second portion 1304 may comprise a second coolant channel 1314, and / or the third portion 1306 may comprise a third coolant channel 1316. The cold plate 1308 may comprise one or more coolant channels. For example, the cold plate 1308 may comprise a fourth coolant channel 1318 and a fifth coolant channel 1320.

[0137] In some embodiments, one or more characteristics of coolant channels or openings between coolant channels my vary to effect coolant flow. For example, the third portion 1306 of the manifold 1301 may comprise a first plurality of openings 1322a-f and a second plurality of openings 1324a-e. The opening may allow coolant to flow between one or more coolant channels of the third portion 1306 of the manifold 1301 and one or more coolant channels of the cold plate 1308. For example, the first plurality of openings 1322a-f mayallow coolant to flow between the third coolant channel 1316 and the fourth coolant channel 1318 and the second plurality of openings 1324a-e may allow coolant to flow between the third coolant channel 1316 and the fifth coolant channel 1320. In some embodiments, one or more openings of the first plurality of openings 1322a-f has a first characteristic (e.g., number, length, width, height, shape, diameter, cross-section, etc.) and one or more openings of the second plurality of openings 1322a-e has a second characteristic (e.g., number, length, width, height, shape, diameter, cross-section, etc.).

[0138] In some embodiments, the plurality of openings have different characteristics to direct coolant flow. For example, the first plurality of openings 1322a-f may comprise a first number (e.g., six) of openings and the second plurality of openings 1324a-e may comprise a second number (e.g., five) of openings. The amount of coolant that flows to the fourth coolant channel 1318 may be more than the amount of coolant that flows to the fifth coolant channel 1320 based, at least in part, on the first plurality of openings 1322a-f comprising a larger number (e.g., six) of openings than the second plurality of openings 1324a-e.

[0139] In another example, the first plurality of openings 1322a-f may comprise a first width in the x-direction and the second plurality of openings 1324a-e may comprise a second width in the x-direction, wherein the first width is larger than the second width. The amount of coolant that flows to the fourth coolant channel 1318 may be more than the amount of coolant that flows to the fifth coolant channel 1320 based, at least in part, on the first plurality of openings 1322a-f having a larger width in the x-direction than the second plurality of openings 1324a-e.

[0140] In another example, the first plurality of openings 1322a-f may comprise a first height in the z-direction and the second plurality of openings 1324a-e may comprise a second height in the z-direction, wherein the first height is shorter than the second height. The amount of coolant that flows to the fourth coolant channel 1318 may be more than the amount of coolant that flows to the fifth coolant channel 1320 based, at least in part, on the first plurality of openings 1322a-f having a smaller height in the z-direction than the second plurality of openings 1324a-e.

[0141] In some embodiments, the one or more opening of the first plurality of openings 1322a-f and the one or more openings of the second plurality of openings 1322a-e may have more than one characteristic (e.g., number, length, width, height, shape, diameter, crosssection, etc.). For example, the first plurality of openings 1322a-f may comprise a first characteristic (e.g., six openings) and a second characteristic (e.g., first width in the x-direction) and the second plurality of openings 1324a-e may comprise a third characteristic (e.g., five openings) and a fourth characteristic (e.g., second width in the x-direction). The amount of coolant that flows to the fourth coolant channel 1318 may be more than the amount of coolant that flows to the fifth coolant channel 1320 based, at least in part, on the first characteristic, second characteristic, third characteristic, and / or fourth characteristic. In some embodiments, the characteristics are selected based on hot spots. For example, the semiconductor device 1310 may comprise a hot spot 1330. The manifold 1301 may be designed to direct more coolant to one or more coolant channels (e.g., fourth coolant channel 1318) that are closer to the hot spot compared to one or more coolant channels (e.g., fifth coolant channel 1320) further away from the hot spot. For example, the first plurality of openings 1322a-f may comprise a first number (e.g., six) of openings and the second plurality of openings 1324a-e may comprise a second number (e.g., five) of openings.

[0142] The embodiments discussed above are intended to be illustrative and not limiting. One skilled in the art would appreciate that individual aspects of the cooling assemblies, device packages, and methods discussed herein may be omitted, modified, combined, and / or rearranged without departing from the scope of the disclosure.

Claims

What is claimed is:

1. A device package comprising:a substrate;a first semiconductor device disposed on the substrate;a cold plate attached to the first semiconductor device, wherein the cold plate comprises a plurality of coolant channels; anda manifold attached to the cold plate, wherein:a first portion of the manifold comprises a first coolant channel and a second coolant channel;a second portion of the manifold comprises a third coolant channel and a fourth coolant channel;a third portion of the manifold comprises a fifth coolant channel and a sixth coolant channel;the third portion of the manifold is attached to the cold plate;the fifth coolant channel and the sixth coolant channel are coupled to at least one coolant channel of the plurality of coolant channels of the cold plate; andthe second portion of the manifold is between the first portion of the manifold and the third portion of the manifold.

2. The device package of claim 1, wherein the first coolant channel is coupled to a first coolant line and the second coolant channel is coupled to a second coolant line.

3. The device package of claim 1, wherein:the third coolant channel is coupled to the first coolant channel; andthe fourth coolant channel is coupled to the second coolant channel.

4. The device package of claim 3, wherein:the fifth coolant channel is coupled to the third coolant channel; andthe sixth coolant channel is coupled to the fourth coolant channel.

5. The device package of claim 4, wherein coolant is disposed in the first coolant channel, the second coolant channel, the third coolant channel, the fourth coolant channel, thefifth coolant channel, the sixth coolant channel, and the at least one coolant channel of the plurality of coolant channels of the cold plate.

6. The device package of claim 1, wherein the cold plate is attached to the first semiconductor device by direct dielectric bonds.

7. The device package of claim 1, wherein the cold plate is attached to the first semiconductor device by direct hybrid bonds.

8. The device package of claim 1, wherein the manifold is attached to the cold plate using at least one of one or more adhesives, one or more gaskets, and one or more O-rings.

9. The device package of claim 1, wherein the manifold comprises a plastic.

10. The device package of claim 1, wherein the manifold comprises a metal.

11. The device package of claim 1, wherein the manifold is attached to the cold plate using one or more adhesives.

12. The device package of claim 1, wherein the first portion of the manifold is attached to the second portion of the manifold using an adhesive material.

13. The device package of claim 12, wherein the second portion of the manifold is attached to the third portion of the manifold using an additional adhesive material.

14. The device package of claim 1, wherein:the third portion of the manifold comprises a seventh coolant channel; and the plurality of coolant channels comprise a first cold plate coolant channel and a second cold plate coolant channel.

15. The device package of claim 14, wherein:the fifth coolant channel is coupled to the first cold plate coolant channel; and the seventh coolant channel is coupled to the second cold plate coolant channel.

16. The device package of claim 15, wherein:the fifth coolant channel delivers coolant at a first rate to the first cold plate coolant channel;the seventh coolant channel delivers coolant at a second rate to the second cold plate coolant channel; andthe first rate is different than the second rate.

17. The device package of claim 16, wherein:the first rate is larger than the second rate; andthe first cold plate coolant channel is disposed over a hot spot of the first semiconductor device.

18. The device package of claim 15, wherein:the fifth coolant channel has a first characteristic;the seventh coolant channel has a second characteristic; andthe first characteristic is different than the second characteristic.

19. The device package of claim 18, wherein the first characteristic corresponds to at least one of a length of the fifth coolant channel, a width of the fifth coolant channel, a height of the fifth coolant channel, a shape of the fifth coolant channel, and a diameter of the fifth coolant channel.

20. The device package of claim 18, wherein:the first characteristic corresponds to a first diameter;the second characteristic corresponds to a second diameter; andthe first diameter is larger than the second diameter.

Images