Integrated heat spreader with enhanced vapor chamber for multichip packages

An integrated circuit package includes a first die and second die above a substrate, and a vapor chamber above at least one of the first and second die. A vapor space within the vapor chamber is separated into at least a first section and a second section. The first section may be over the first die, and the second section may be over the second die, for example. The structure separating the first and second sections at least partly restricts flow of vapor between the first and second sections, thereby preventing or reducing thermal cross talk between the first and second dies. In some cases, an anisotropic thermal material is above one of the first or second die, wherein the anisotropic thermal material has substantially higher thermal conductivity in a direction of a heat sink than a thermal conductivity in a direction of a section of the vapor chamber.

BACKGROUND

Integrated circuitry continues to scale to smaller feature dimensions and higher packaging densities. With such scaling, the density of power consumption of a given microelectronic device within a given package tends to increase, which, in turn, tends to increase the average junction temperature of transistors of that device. If the temperature of the microelectronic device becomes too high, the integrated circuits in the device may be damaged or otherwise suffer performance issues (e.g., sub-optimal performance such as low gain or slow switching speeds, or catastrophic failure where one or more portions of the integrated circuitry is destroyed). This issue is exacerbated when multiple microelectronic devices are incorporated in close proximity to one another in a given die layout. For example, when two or more devices are in close proximity, heat has to dissipate from these devices. Thus, thermal transfer solutions, such as integrated heat spreaders, have to be utilized to remove heat from such devices. There are a number of non-trivial and unresolved issues associated with thermal management.

The figures depict various embodiments of the present disclosure for purposes of illustration only. Numerous variations, configurations, and other embodiments will be apparent from the following detailed discussion. Furthermore, as will be appreciated, the figures are not necessarily drawn to scale or intended to limit the described embodiments to the specific configurations shown. For instance, while some figures generally indicate straight lines, right angles, and smooth surfaces, an actual implementation of the disclosed techniques may have less than perfect straight lines and right angles, and some features may have surface topography or otherwise be non-smooth, given real-world limitations of fabrication processes. In short, the figures are provided merely to show example structures.

DETAILED DESCRIPTION

Techniques are disclosed for forming an integrated circuit package structure (also referred to as a package) that includes multiple dies laid out in a desired pattern. In an embodiment, the package has a first die and a second die, and a vapor chamber is above the first and second dies. The vapor chamber effectively acts as an integrated heat spreader. The vapor chamber has a wick layer (e.g., comprising appropriate wicking mechanism) on a bottom plate, a vapor space above the wick layer, and a top plate above the vapor space. A heat sink may be above the top plate. In one such example scenario, assume that the first die consumes higher power, operates at a higher temperature, and generates higher amount of thermal energy than the second die. Thus, vapor generated in the vapor space due to heat from the first die may be at a higher temperature than vapor generated in the vapor space due to heat from the second die. As such, a standard vapor chamber may be susceptible to thermal crosstalk, much like a standard integrated heat spreader. To this end, and according to an embodiment, the vapor chamber is modified to limit or otherwise inhibit thermal crosstalk. For instance, the vapor chamber can be effectively segmented with one or more baffles or anisotropic thermally conductive material to prevent thermal cross-talk. As will be appreciated in light of this disclosure, such baffles and/or anisotropic thermally conductive material can be utilized to effectively isolate differing heat sources of a given integrated circuit structure, or to otherwise control the manner in which heat is dissipated from that structure.

In some embodiments, for instance, the vapor chamber comprises a baffle or a separator that segregates the vapor space into at least a first section and a second section. For example, the first section is above the first die, and the second section is above the second die. Thus, vapor generated in the vapor space due to heat from the first die may be at least in part confined within the first section of the vapor space, and vapor generated in the vapor space due to heat from the second die may be at least in part confined within the second section of the vapor space. So, vapor generated in the vapor space due to heat from the first die (e.g., which may be at a higher temperature) is inhibited from fully interacting or mixing with vapor generated in the vapor space due to heat from the second die (e.g., which may be at a lower temperature). Without such a baffle or separator, vapors from the two sections would interact, and increase temperature of the second section, thereby potentially resulting in temperature rise of the second die. However, the baffle separates the vapors from the two sections, and thus, prevents or otherwise reduces thermal crosstalk between the first die and the second die, i.e., the two dies are thermally decoupled.

In some other embodiments, the thermal decoupling between the two dies may be achieved by using separate thermal management techniques for the first die and the second die. For example, a vapor chamber is above the first die (and not above the second die), and transfers heat from the first die to a heat sink. An appropriate anisotropic thermally conductive material (e.g., Pyrolytic Graphite) in an opening within the vapor chamber is above the second die. The anisotropic thermally conductive material has high in-plane thermal conductivity and low through-thickness conductivity. Thus, heat can be conducted through the material in certain directions, and may not be conducted in certain other directions, thereby providing the anisotropic heat conductive properties. The directional thermal conductivity of the anisotropic thermally conductive material may be used to transfer heat from the second die towards the heat sink, and to prevent transferring of heat from the second die towards the first die, thus, preventing any thermal crosstalk between the first die and the second die, i.e., the two dies are thermally decoupled.

General Overview

As noted above, there are a number of non-trivial and unresolved issues associated with thermal management solutions for integrated circuitry, particularly with respect to integrated circuit packages that include multiple dies, one or more of which require relatively high-power (e.g., compared to another one or more dies of the package). For instance, consider a semiconductor package100ofFIG.1, which includes multiple dies102,104a,104bmounted on a substrate106, where an integrated heat spreader108allows for thermal crosstalk between the dies, which can adversely affect performance of one or more of these dies. As can be seen, the substrate106has package interconnect structures122on a first side, and the dies102,104a,104bon an opposing second side. The heat spreader108is attached to the dies102,104a,104b, e.g., through thermally conductive bonding layer110(e.g., which may be a thermal interface layer). A section of the heat spreader108may also be coupled to the substrate106through thermally conductive bonding layer112. In an example, the die102generates higher amount of heat compared to each of the dies104a,104b. The heat spreader108tends to remove the heat generated by the dies102,104a,104b. The dotted arrows are example paths through which heat can possibly dissipate from the dies102,104a,104bto the heat spreader108. As illustrated, heat from the die102can be dissipated at or near the dies104a,104b, thereby leading to thermal crosstalk between the dies102and104a,104b, which may elevate the temperature of the dies104a,104b. That is, heat from the high-powered die102may spread to the adjacent smaller, lower heat generating dies104a,104b, which may heat up the dies104a,104b. Such thermal coupling and thermal crosstalk between the die102and the dies104a,104bmay adversely affect performance of the dies104a,104b.

As die and package size decreases, power consumption and heat generation of individual die increases, and multiple dies are packaged in the same package in close proximity, thermal crosstalk can cause thermal management issues. Elevated die temperature during operation can result in thermal throttling, e.g., reduction in the number of computational cycles per unit time that may be performed and can also increase the likelihood of a reliability failure of the dies. To this end, the present disclosure provides techniques to remove heat generated by dies within an integrated circuit package in a manner that prevents or otherwise reduces thermal crosstalk between the dies. Many variations will be apparent in light of this disclosure.

Architectures

FIG.2Aillustrates a cross-sectional view,FIG.2Billustrates a top down view, andFIGS.2C-2Dillustrate perspective partially separated views of an integrated circuit package structure200(also referred to microelectronics package200, a package200, an apparatus200, a structure200, or the like) that includes a vapor chamber230that acts as a heat spreader, where a vapor flow of the vapor chamber230is obstructed at least in part using baffles238a,238bto prevent thermal crosstalk between two or more dies of the structure200, in accordance with an embodiment of the present disclosure. The cross-sectional view ofFIG.2Ais along line A-A′ of the top down view ofFIG.2B. It is to be noted thatFIGS.2B,2C,2Ddo not illustrate all components of the package200as will be appreciated.

The package200includes a package substrate206. The substrate206is coupled to a number of integrated circuits thereon in the form of two or more die, e.g., dies202,204a,204b, etc. The substrate206can be an epoxy-based laminate substrate having a core and/or build-up layers such as, for example, an Ajinomoto Build-up Film (ABF) substrate. The substrate206may include other suitable types of material in other embodiments including, for example, substrates formed from glass, ceramic, polymer, or semiconductor materials (e.g., silicon or gallium arsenide), and/or combinations thereof (e.g., a composite comprising a polymer matrix that includes layers or elements of silicon or another semiconductor material).

In an example, the die202is between the dies204a,204c. For merely, merely for purposes of ease of identification, the die202may be referred to as a center die, and dies204a,204bmay be referred to as peripheral dies. Although merely three dies are illustrated inFIGS.2A-2D, the package200can include more than three dies, e.g., two, four, or higher, as will be discussed herein later. Although the dies204a,204b,202are illustrated to be arranged in a side-by-side configuration in the package200, the dies may be arranged in any other appropriate configuration. Merely as an example, two or more dies may be stacked (e.g., vertically stacked on top of each other) within the package202. Elements referred to herein with a common reference label followed by a particular number, letter or alphabet may be collectively referred to by the reference label alone. For example, dies204a,204bmay be collectively and generally referred to as dies204(or peripheral dies204) in plural, and die204(or peripheral die204) in singular.

In an example and without limiting the scope of this disclosure, the center die202is a processor die (e.g., includes a central processing unit or CPU, graphics processing unit or GPU, or the like), and the two dies204a,204bare memory dies (e.g., comprises high bandwidth memory, or HBM). In an example, the die202has a larger area (e.g., in the X-Y plane) than each of the dies204a,204b. In an example, the die202consumes more power and generates more heat than each of the dies204a,204b.

Interconnect structures212are disposed on a die-side surface of the substrate206, and package interconnect structures210are disposed on an opposite surface of the substrate206. The interconnect structures210,212, for example, are bumps, metal pillars (e.g., copper pillars), balls formed using metals, ball grid array or pins, land grid array, pin grid array, alloys, solderable material, or the like. The interconnect structures210,212, for example, are solder formed using metals, alloys, solderable material, and/or the like. For example, the interconnect structures212may comprise solder balls of any configuration formed on the dies202,204and the substrate206at appropriate locations (e.g. contact pads), e.g., so that when the dies202,204and the substrate206are placed together, the interconnect structures212can be melted or reflowed, thus physically and electrically connecting the dies202,204to the substrate206. The interconnect structures210similarly are package interconnect structures used to attach the substrate206to a substrate208.

Although not illustrated in the figures, pads, electrically conductive vias, traces, redistribution layers, routing layers, interconnect bridges (e.g., an embedded multi-die interconnect bridge), etc. can be disposed on various layers of the substrate206, thus providing electrical connection between the dies202,204and the interconnect structures210, and/or among the dies202,204. These electrical interconnections within and/or on the substrate206may comprise any appropriate electrically conductive materials, e.g., copper, gold, silver, aluminum, zinc, nickel, brass, bronze, iron, etc. In an example, the substrate206can include a core and multiple build-up layers, with each build-up layer including an interconnect level (e.g., a routing layer) for trace routing and a dielectric layer for electrically insulating laterally adjacent traces as well as adjacent interconnect levels. Conductive vias and solder connections can pass through the dielectric layer, such as to connect traces in different routing layers.

The substrate208may be a printed circuit board (PCB) composed of an electrically insulative material such as an epoxy laminate. For example, the substrate208may include electrically insulating layers composed of materials such as, for example, polytetrafluoroethylene, phenolic cotton paper materials such as Flame Retardant 4 (FR-4), FR-1, cotton paper and epoxy materials such as CEM-1 or CEM-3, or woven glass materials that are laminated together using an epoxy resin prepreg material. Structures (not shown) such as traces, trenches, vias may be formed through the electrically insulating layers to route the electrical signals of the dies202,204through the circuit board208. The substrate208may be composed of other suitable materials in other embodiments. In some embodiments, the substrate208is a circuit board, a motherboard (e.g., motherboard2002ofFIG.10), an interposer, or the like. The substrate208is also referred to as a circuit board208herein.

The dies202,204, as described above, can include one or more integrated circuits fabricated on a semiconductor material. As shown inFIGS.2A-2D, individual ones of the dies202,204has a first surface that confronts a surface of the substrate206. The first surfaces of the dies202,204are physically and electrically coupled to the substrate206, e.g., by the interconnect structures212. Opposing second surfaces (e.g., back sides) of the dies202,204face the vapor chamber230.

In an example, the dies202,204(e.g., back side of the dies202,204) are bonded to the vapor chamber230through an appropriate thermally conductive bonding material218. A heat sink222is above the vapor chamber, and is bonded to the top surface of the vapor chamber230through an appropriate thermally conductive bonding material220.

The thermally conductive bonding material218,220can be implemented with any number of commercially available or proprietary thermal interface materials (or so-called TIMs), such as thermal grease, thermal adhesive, thermal gap filler, thermally conductive pad, thermal tape, thermal elastomers, phase change materials, graphite pads, curable gels, and solders having relatively high thermal conductivity, etc. (e.g., with K>2 W/m-K, or K>20 W/m-K, or >50 W/m-K, or higher). The thermally conductive bonding material218,220may comprise polymer filled with thermally conductive particles or a film or sheet of thermally conductive metal (e.g., TIM), and can smooth the surface topography (e.g., micron-scale bumps and depressions) of the respective surface to which they are applied. By coating the surface topography of the surface by the thermally conductive bonding material, a proportion of surface area through which heat transfer can occur is increased. The bonding material218increases the rate at which heat is removed from the dies202,204to the vapor chamber230, and the bonding material220increases the rate at which heat is removed from the vapor chamber230to the heat sink222.

It is to be noted that the top down view ofFIG.2Billustrates a top surface of the vapor chamber230(e.g., without illustrating the heat sink222), and symbolically illustrates the underlying dies202,204using dotted lines. The perspective, partially separated view ofFIG.2Dseparately illustrates two sections of the vapor chamber230(as will be discussed in further details herein), whileFIG.2Cdoes not separate the two sections. The perspective, partially separated views ofFIGS.2C-2Ddo not illustrate various components, such as the bonding material218,220, the heat sink222, the interconnect structures210,212, the substrate208, etc.

Referring again toFIGS.2A-2D, the vapor chamber230includes a top plate235and a bottom plate237, and vapor space234and wick layer232therebetween. The vapor chamber230also includes sidewalls extending between the top plate235and the bottom plate237, e.g., sidewalls239a,239b,240a,240b. The sidewalls239a,239bare not illustrated inFIGS.2C-2D, such that components of the vapor chamber230between these sidewalls are visible.

The vapor chamber230is a hermitically sealed chamber and is maintained at low pressure (e.g., at near vacuum pressure, at pressure lower than atmospheric pressure, or the like). The vapor chamber230is filled with working fluid (also referred to as coolant, not illustrated inFIGS.2A-2D) that, when heated, changes phase from liquid to gas, and vice versa. The wick layer232is above the bottom plate237, and the vapor space234is above the wick layer232. In an example, the wick layer232comprises any appropriate wicking material, such as a screen mesh, sintered copper powder wick that may be made from a metal, such as copper, and/or the like. Other materials that may be used as the wick include fabrics, non-woven plastic fabrics, fiberglass, and the like. Although the wick layer232is illustrated to be on the bottom plate237, wicking material may also be on the sidewalls of the vapor chamber230, between the top plate235and the bottom plate237(e.g., on posts309illustrated inFIG.3A), on sidewalls of the baffles238, and/or the like.

In operation, liquid phase of the working fluid at or near the bottom plate237(e.g., within or near the wick layer232) gets heated from the heat generated by the dies202,204, and evaporates. Thus, the wick layer232and adjacent area near the bottom plate237are also referred to as evaporation end. The evaporated working fluid raises towards the top plate235. For example, the vapor space234is filled with vapor, i.e., the evaporated working fluid. The top plate235is cooler than the bottom plate, e.g., due to the operation of the heat sink222. When the evaporated working fluid reaches or is near the top plate235, the working fluid cools down and condenses to liquid. Thus, area near or at the top plate is also referred to as condensation end of the vapor chamber230. For example, in the vapor chamber230, the vaporized coolant circulates via convection within the vapor space233. The molecules of the coolant condense on cold surfaces (e.g., which are cold due to the action of the heat sink222), dissipate their heat load, and are channeled back to the coolant reservoir comprising the wick layer232. The wick layer232(also referred to as a wick structure) exerts a capillary pressure on the cooled down liquid phase of the working fluid, thereby moving the liquid coolant from the condensation end back to the evaporation end (e.g., moving the cooled down liquid phase of the working fluid to areas where the dies202,204emit most heat). The vapor chamber230is able to absorb and dissipate large amounts of heat through this method. Condensation varies based on the change in temperature between the coolant and the contact surface of the top plate235. The vapor chamber230can be setup in a way that the coolant will automatically stream towards the coolest surface area. This self-organization of the coolant molecules within the vapor chamber provides superior thermal properties.

In some examples, the vapor chamber230comprises one or more baffles, such as baffles238a,238b. The baffles are also referred to as, and act as, vapor barrier structures, vapor obstruction structures, separation structures, barriers, barrier structures, walls, and/or the like. The baffles238, as illustrated in the cross-sectional view ofFIG.2Aand the perspective view ofFIGS.2C-2D, are attached to the top plate235of the vapor chamber230. For example, the baffles238hang from the top plate235of the vapor chamber230. In the example ofFIGS.2A-2D, the baffles238do not extend through the wick layer232disposed above the bottom plate237. Thus, in the example ofFIGS.2A-2D, the baffles238are within the vapor space234(e.g., and not within the wick layer232), and separates the vapor space232into multiple sections, such as sections236a,236b,236c.

In an example, the die204a(or at least a section of the die204a) is underneath the section236a, the die202(or at least a section of the die202) is underneath the section236b, and the die204b(or at least a section of the die204b) is underneath the section236c, as illustrated inFIGS.2A-2B.

Thus, when the dies202,204a,204bare in operation and generates heat, liquid coolant in a section of the wick layer232above the die202evaporates to the vapor space section236bdue to the heat generated by the die202. Similarly, liquid coolant in a section of the wick layer232above the die204aevaporates to the vapor space section236adue to the heat generated by the die204a. Also, liquid coolant in a section of the wick layer232above the die204bevaporates to the vapor space section236cdue to the heat generated by the die204b. The baffles238a,238bat least in part keep the evaporated coolant from the various sections of the wick layer232separate. For example, the baffle238aseparates the evaporated coolant generated due to the heat from the die202from the evaporated coolant generated due to the heat from the die204a. That is, the evaporated coolant generated due to the heat from the die202cannot readily interact and mix with the evaporated coolant generated due to the heat from the die204a. Similarly, the baffle238bseparates the evaporated coolant generated due to the heat from the die202from the evaporated coolant generated due to the heat from the die204b. That is, the evaporated coolant generated due to the heat from the die202cannot readily interact and mix with the evaporated coolant generated due to the heat from the die204b.

Assume, merely as an example, that the die202generates higher amount of heat and/or is operating at a higher temperature than the die204a(or from the die204b). Thus, the evaporated coolant generated due to the heat from the die202may be at a higher temperature than the evaporated coolant generated due to the heat from the die204b. If the baffle238aare not present in the vapor chamber230, the two evaporated coolants (i.e., evaporated coolants generated due to heat from dies202and204a) would mix and interact, thereby elevating the temperature of the section236aof the vapor space234, which would result in a raise of temperature of the die204aand lead to thermal crosstalk between the dies202and204a(e.g., as discussed with respect toFIG.1).

However, the baffle238aprevents or at least reduces such thermal crosstalk between the dies202and204a. For example, the baffle238aseparates the higher temperature evaporated coolant of the section236b(e.g., which are generated due to large amount of heat from the die202) from the relatively lower temperature evaporated coolant of the section236a(e.g., which are generated due to lower amount of heat from the die204a), thereby preventing or reducing thermal crosstalk between the dies202and204a. Similarly, the baffle238bseparates the higher temperature evaporated coolant of the section236b(e.g., which are generated due to heat from the die202) from the relatively lower temperature evaporated coolant of the section236c(e.g., which are generated due to heat from the die204b), thereby preventing or reducing thermal crosstalk between the dies202and204c. It is to be noted that in the example ofFIGS.2A-2D, the baffles238a,238brestrict the vapor flow, but does not block flow of relatively cooler liquid phase of the coolant through the wick layer232.

As more clearly illustrated in the top down view ofFIG.2B, the section236aof the vapor space234is partially, but not fully, separated from the section236bby the baffle238a. Similarly, the section236bof the vapor space234is partially, but not fully, separated from the section236cby the baffle238b. In an example, as illustrated in the top down view ofFIG.2B, the vapor chamber230has a length of L1along the direction of Y axis (e.g., between sidewalls239a,239b), and the baffle238ahas a length of L2, where L2is less than L1. Merely as an example, L1may be in the range of 40-60 millimeter (mm), and L2may be in the range of 20-35 mm. The die202may have a length of L3, where L3is less than L2in an example. For example, L3may be at least 5 mm, or 10 mm less than L2.

Thus, as illustrated inFIG.2B, a first end of the baffle238afaces the sidewall239aand an opposing second end of the baffle238afaces the sidewall239b. The first end of the baffle238adoes not extend to the sidewall239a, and the second end of the baffle238adoes not extend to the sidewall239b. Thus, the section236aand236care connected through a space between the first end of the baffle238aand the sidewall239a, and are also connected through a space between the second end of the baffle238aand the sidewall239b.

Thus, because L2is less than L1, the sections236a,236b,236care at least in part connected, which allows some flow of vapor (e.g., after the vapor has cooled to an extent, e.g., after being in contact with, or near the top plate235) between these sections. In an example, fully separating the vapor space234into the sections236a,236b,236c(e.g., by extending the baffles238from one sidewall239ato the opposing sidewall239b) may, for example, reduce the vapor space area for the vapor generated by the heat of the die202. Also, as the die202generates the most heat in an example (e.g., compared to the dies204a,204c), partially connecting the section236bwith the sections236a,236cexpands the cooling capacity of the section236c, and yet the baffles238a,238bprevent or reduce the thermal crosstalk between the dies202and204a,204b. Thus, in an embodiment, the vapor chamber230acts as a heat spreader, to transfer heat from the dies204to the heat sink222, while preventing or reducing thermal crosstalk between the dies202and204a,204b.

The coolant used in the vapor chamber230may be any suitable coolant, such as, but not limited to, water, ethanol, acetone, and/or the like. In an example, the baffles238, top and bottom plates235,237, and/or the sidewalls239a,239b,240a,240bof the vapor chamber230are of any appropriate thermally conductive material, such as metal. Example metals include, but are not limited, to copper and aluminum. The selection of the metal may be based on the type of coolant used. For example, copper or copper alloys may be used with a water phase change fluid, which may be less expensive and more efficient than other typical coolants. Aluminum may also provide a cost advantage over copper. However, water cannot be used as a coolant in aluminum vapor chamber because hydrogen gas results from the interaction of water with the aluminum.

FIG.2Eillustrates a cross-sectional view of a vapor chamber230that acts as a heat spreader in as similar fashion to the vapor chamber ofFIGS.2A-2D, except that one or more of the sidewalls of the vapor chamber230extend downward to contact the package substrate206(e.g., through a thermally conductive bonding layer292), in accordance with an embodiment of the present disclosure. As discussed previously, in an embodiment, the vapor chamber230acts as a heat spreader, to transfer heat from the dies204to the heat sink222, while preventing or reducing thermal crosstalk between the dies202and204a,204b. In an example, sections of the vapor chamber230, such as one of more sections of the sidewalls239a,239b,240a,240b, are coupled to the substrate206through thermally conductive bonding layer292(e.g., which may be similar to any of the thermally conductive bonding layers218,220).

FIG.3Aillustrates a perspective view andFIG.3Billustrates a top down view of another example vapor chamber that is similar to the vapor chamber ofFIGS.2A-2E, except that it further includes one or more posts309that are different from the baffles238, in accordance with an embodiment of the present disclosure. As noted above, the vapor chamber230is a hermitically sealed chamber and is maintained at low pressure (e.g., near vacuum pressure, at pressure lower than atmospheric pressure, or in between). The posts309, for example, prevent collapse of the flat top plate235and the bottom plate237of the vapor chamber, when the pressure within the vapor chamber230is relatively low (e.g., lower than atmospheric). Although three posts309are illustrated, there may be any number of such posts309, such as zero, one, two, four, or higher. As seen, the posts309are different and separate from the baffles238. For example, the posts309may be tube like structures having a cross-sectional width or diameter L4(e.g., along Y axis) that is significantly less (e.g., 60% or less, 50% or less, 20% or less, 10% or less, or the like) than the length L2of the baffles238. Furthermore, in the example ofFIGS.2A-3B, the baffles238extend through the vapor space234but not through the wick layer232, while the posts309extend between the top plate235and bottom plate237(e.g., extend through the vapor space234and the wick layer232). Sections of the posts309within the wick layer232are illustrated using dotted lines inFIG.3A.

FIG.4illustrates a top down view of an integrated circuit package structure that is similar to the structure ofFIGS.2A-2E, except that there are more than one die underneath individual sections of the vapor chamber230, in accordance with an embodiment of the present disclosure. For example, dies204a1and204a2are underneath the section236aof the vapor space234, dies202aand202bare underneath the section236bof the vapor space234, and dies204b1and204b2are underneath the section236cof the vapor space234. Thus, the baffle238aprevents thermal cross talk between the dies202a,202band the dies204a1,204a2; and the baffle238bprevents thermal cross talk between the dies202a,202band the dies204b1,204b2.

FIG.5illustrates a top down view of an integrated circuit package structure that is similar to the structure ofFIGS.2A-2E, except that this example configuration has a different shape (e.g., non-linear shape) of baffles238a′,238b′, in accordance with an embodiment of the present disclosure. The baffles238′ ofFIG.5better segregate or separate the sections236a,236b,236c, increase an area of the section236b(e.g., as the section236bmay be responsible for cooling the high heat producing die202), and prevent thermal crosstalk between these sections. Similar to the discussion with respect toFIGS.2A-2D, the baffles238a′,238b′ extend through the vapor space234, but does not extend through the wick layer232. For example, the baffle238a′ has a mid-section that is substantially parallel to a side of one or more of the dies204a,202. A first end-section is at an angle θ1with respect to the mid-section, and a second end-section is at an angle θ2with respect to the mid-section. As illustrated, each of angles θ1,02is substantially higher than 90 degrees, e.g., higher than 100, 110, or 120 degrees. The non-linear shape of the baffles238a′,238b′ is merely an example, and the baffles238a′,238b′ may have any other appropriate non-linear shape.

FIG.6illustrates a top down view of an integrated circuit package structure that is similar to the structure200ofFIGS.2A-2D, except that baffles638a,638bsubstantially separate the sections236a,236b,236cof the vapor chamber230, in accordance with an embodiment of the present disclosure. ComparingFIGS.2B and6, inFIG.2Bthe baffles238a,238bpartially separate the sections236a,236b,236cfrom each other, whereas inFIG.6the baffles638,638bsubstantially or fully separate the sections236a,236b,236cfrom each other. Thus, inFIG.6, the baffles638extend from one sidewall239aof the vapor chamber230to the opposing sidewall239b. Hence, the length of the vapor chamber230is L1(e.g., in the direction of Y axis between sidewalls239a,239b), and the length of one or both the baffles638a,638bis also L1. Similar to the discussion with respect toFIGS.2A-2D, the baffles638a,638bextend through the vapor space234, but does not extend through the wick layer232.

FIG.7illustrates a top down view of an integrated circuit package structure that is similar to the structure ofFIGS.2A-2E, except that baffles738a,738bsubstantially separate sections of the vapor chamber230and have a non-linear shape, in accordance with an embodiment of the present disclosure. ComparingFIGS.5and7, inFIG.5the baffles238a′,238b′ have non-linear shape and partially separate the sections236a,236b,236cfrom each other, whereas inFIG.7the baffles738,738bhave non-linear shape and fully separate the sections236a,236b,236cfrom each other. Thus, inFIG.7, the baffles738extend from one sidewall239aof the vapor chamber230to the opposing sidewall239b. Similar to the discussion with respect toFIGS.2A-2D, the baffles738a,738bextend through the vapor space234, but does not extend through the wick layer232. The non-linear shape of the baffles738a,738bis merely an example, and the baffles738a,738bmay have any other appropriate non-linear shape.

FIG.8Aillustrates a cross-sectional view,FIG.8Billustrates a top down view, andFIG.8Cillustrates a perspective partially separated views of an integrated circuit package structure800(also referred to microelectronics package800, a package800, an apparatus800, or a structure800) that includes a vapor chamber830, where a vapor flow of the vapor chamber830is obstructed at least in part using baffles838a,838bthat extend through the vapor space234and the wick layer232of the vapor chamber, in accordance with an embodiment of the present disclosure.

Various components of the structure800ofFIGS.8A-8Care at least in part similar to the corresponding components of the structure200ofFIGS.2A-2D, and similar components are labelled using same labels in these two structures. For example, similar to the structure200, the structure800ofFIGS.8A-8Ccomprises the substrates206,208, interconnect structures210,212, dies204a,204b,202, heat sink222, and thermally conductive bonding layers218,220. Furthermore, the structure800also comprises the vapor chamber230including the top plate235, bottom plate237, and the vapor space234and the wick layer232. However, unlike the baffles238of the structure200(e.g., which did not extend through the wick layer232), the baffles838a,838bextend from the top plate235to the bottom plate237of the vapor chamber, i.e., extend through the vapor space234as well as the wick layer232.

Thus, the baffles838not only prevent thermal crosstalk through the vapor space234, but also prevents thermal crosstalk through the wick layer232. For example, the wick layer232, using capillary action, transports liquid coolant. The liquid coolant carried by a section of the wick layer232above the die202may be at a higher temperature than the liquid coolant carried by sections of the wick layer232above the dies204a,204b, thereby causing thermal crosstalk between the die202and the dies204a,204bthrough the wick layer232. However, extending the baffles838through the wick layer232prevents, or at least reduces, such thermal crosstalk through the wick layer232.

Thus, unlike the structure200(e.g., where the vapor space234was separated by the baffles238, and the wick layer232was not separated), in the structure800, the section236anow comprises a first section of the vapor space234and a first section of the wick layer232, the section236bnow comprises a second section of the vapor space234and a second section of the wick layer232, and the section236cnow comprises a third section of the vapor space234and a third section of the wick layer232.

As seen inFIG.8B(and as also discussed with respect toFIG.2B), the baffles838extend only along a section of the length (e.g., along the Y axis) of the vapor chamber230(i.e., the baffles838do not extend to the sidewalls239a,239b). Thus, the sections236a,236b,236care partially, but not fully, separated by the baffles838. However, in an example (and although not illustrated), the baffles838a,838bmay substantially separate the sections236a,236b,236cof the vapor chamber230. That is, in this example, one or both the baffles838a,838bmay extend from one sidewall239aof the vapor chamber230to the opposing sidewall239b(e.g., as discussed with respect toFIG.6). Hence, the length of the vapor chamber230is L1(e.g., in the direction of Y axis), and the length of one or both the baffles838a,838bwould also be L1. Thus, in this example, essentially three vapor chambers would be formed, e.g., a first vapor chamber comprising the section236a, a second chamber comprising the section236b, and a third vapor chamber comprising the section236c. The three vapor chambers would respectively be over the dies204a,202, and204b. The three vapor chambers would share a common top plate235and a common bottom pate237, and a common heat sink222.

AlthoughFIGS.8A-8Cillustrate a linear shape of the baffles838, in an example, the baffles838may have a non-linear shape, e.g., as discussed with respect toFIG.5. In an example, such a non-linear baffle may extend from one sidewall239aof the vapor chamber230to an opposing sidewall239bof the vapor chamber230, e.g., as discussed with respect to 7.

FIG.9Aillustrates a cross-sectional view, andFIG.9Billustrates a top down view of an integrated circuit package structure900(also referred to microelectronics package900, a package900, an apparatus900, or a structure900) that includes a vapor chamber930and an anisotropic thermally conductive material915(also referred to as anisotropic thermal material915, or simply as material915), to prevent thermal crosstalk between two or more dies of the structure900, in accordance with an embodiment of the present disclosure. The cross-sectional view ofFIG.9Ais along line B-B′ of the top down view ofFIG.9B. Various components of the structure900ofFIGS.9A-9Bare at least in part similar to the corresponding components of the structure200ofFIGS.2A-2C. For example, similar to the structure200, the structure900ofFIGS.9A-9Bcomprises substrates906,908, interconnect structures910,912, heat sink922, and thermally conductive bonding layers918,920.

In an example, the structure900comprises one or more dies, e.g., dies902a,902babove a first section of the substrate906; and one or more dies, e.g., dies904a,904b, . . . ,904N above a second section of the substrate906, as illustrated in the top down view ofFIG.9B(inFIG.9B, the dies underneath the vapor chamber and the material915is symbolically illustrated using dotted lines). In the cross-sectional view, merely three dies904a,904b,902are visible.

The structure900also comprises the vapor chamber930comprising a vapor space934(illustrated using shaded region) and wick layer932. The vapor chamber930is above the second section of the substrate906, e.g., above the dies904a,904b, . . . ,904N. In an example, the vapor chamber930is arranged in a loop above the dies904, and a central region of the package900(e.g., above the die202) does not have the vapor chamber930. That is, the vapor chamber930has an opening above the dies902a,902b. The vapor chamber930extracts heat from the dies904and dissipates the heat through the heat sink922. However, as the vapor chamber930is not above the dies902, the vapor chamber930does not transfer heat from the dies902.

In an example, the material915is within the opening in the vapor chamber930. In an example, the material930has high in-plane thermal conductivity (e.g., 1,000 W/m-° K or more at room temperature) and low through-thickness conductivity (e.g., high thermal conductivity in y direction and z direction, and low conductivity in x direction). Thus, heat can be conducted through the material in certain directions, and may not be conducted in certain other directions, thereby providing the anisotropic heat conductive properties of the material915. The arrows within the material915inFIGS.9A-9Billustrate directions of high thermal conductivity of the material915. For example, the material915is formed such that the material915can conduct heat in the direction of Z-axis (e.g., as illustrated inFIG.9A) and in the direction of Y-axis (e.g., as illustrated inFIG.9B). However, thermal conductivity of the material915in the direction of the X-axis is poor or relatively low (e.g., less than 15 W/m-° K).

An example of the material915is Pyrolytic Graphite (PG). For example, Pyrolytic Graphite can be annealed to form Annealed Pyrolytic Graphite (APG), also known as Thermally Annealed Pyrolytic Graphite (TPG). Pyrolytic Graphite material, such as Thermal Pyrolytic Graphite (TPG) material, exhibits substantial anisotropic thermal conductivity such that, within the basal plane (e.g., in the direction of Z and Y axis inFIGS.9A-9B), the thermal conductivity can be about 1600 W/m-° K (e.g., four time of copper) and perpendicular to the basal plane (e.g., in the direction of X-axis) is about 10 W/m-° K (e.g., 1/40thof copper). More particularly, graphites possess anisotropic structures and thus exhibit or possess many properties that are highly directional e.g. thermal and electrical conductivity and fluid diffusion. Still more particularly, graphites are made up of layer planes of hexagonal arrays or networks of carbon atoms. These layer planes of hexagonally arranged carbon atoms are substantially flat and are oriented or ordered so as to be substantially parallel and equidistant to one another. The substantially flat, parallel equidistant sheets or layers of carbon atoms, usually referred to as graphene layers or basal planes, are linked or bonded together and groups thereof are arranged in crystallites. A sheet of pyrolytic graphite may be described as having three directional axes; an a-axis and a b-axis which are parallel to the surface of deposition of the basal planes and perpendicular to each other, and a c-axis of which is perpendicular to both the a-axis and the b-axis and to the basal planes. The thermal properties of pyrolytic graphite are strongly affected by its structural anisotropy. Pyrolytic graphite acts as an excellent heat insulator in the c-axis direction (which is along the direction of deposition of the graphite; perpendicular to the plane of the surface upon which the graphite is being deposited) and as a relatively good heat conductor in the planes containing the a-axis and the b-axes. Thus, put differently, in Pyrolytic graphite, rather than dissipating through the thickness of graphite sheets, heat travels primarily along the length of the sheets, thus conducting heat in a desired path to a particular destination. In the structure900, the material915has a thermal conductivity of more than 1500 W/m-° K in the direction of Z-axis and Y-axis, and has a thermal conductivity of less than 15 W/m-° K in the direction of Y-axis. Although Pyrolytic Graphite, such as APG or TPG, is used as the material915in some example embodiments, any appropriate anisotropic thermally conductive material may be used. Pyrolytic carbon may function similarly and thus may also be used. A height of the material915(e.g., in the Z-axis plane) may be about 2 mm or higher, between 1-4 mm, or the like, for example.

In operation, the vapor chamber930extracts heat from the dies904and dissipates the heat through the heat sink922. However, as the vapor chamber930is not above the dies902, the vapor chamber930does not transfer heat from the dies902. Also, the heat from the dies902is dissipated to the material915through the thermally conductive bonding material918. The heat is conducted by the material915vertically upwards, e.g., in the Z direction, and possibly in the Y direction. Due to the vertical transfer of the heat, the heat reaches the top surface of the material915, and is dissipated by the heat sink922. However, due to the poor thermal conductivity along the X direction, the heat from the dies902is not transferred towards the dies904through the material915. Thus, due to the anisotropic thermal conductivity of the material915, the heat from the dies902is able to transfer vertically up to the heat sink922, and cannot reach the dies904. For example, although the heat from the material915may travel in the Y axis direction and reach a section of the vapor chamber930(e.g., seeFIG.9B), no die may be underneath that section of the vapor chamber930. On the other hand, the heat from the material915cannot travel in the X axis direction, and hence, cannot reach sections of the vapor chamber930that are above the dies904. Hence, the structure900prevents, or at least reduces, thermal crosstalk from the dies902to the dies904. That is, the dies902and the dies904are now thermally decoupled or isolated.

In the structure900ofFIGS.9A-9B, the vapor chamber930is above the dies904, and the material915is above the dies902. However, in an example, the role and position of the vapor chamber930and the material915may be reversed. For example, the material915may be above the dies904and may be used to dissipate heat form the dies904. The vapor chamber930may be above the dies902and may be used to dissipate heat from the dies902. In such an example, the material915may be deposited such that the material915has thermal conductivity vertically upwards (e.g., along the Z axis) and also along the Y axis. That is, the material915may have low thermal conductivity in the X-axis direction, thereby preventing heat from the dies904from propagating towards the dies902, thereby thermally decoupling the dies902and the dies904. Thus, in an embodiment, the combination of the vapor chamber930and the material915act as an integrated heat spreader, to transfer heat from the dies902,904to the heat sink922, while preventing or reducing thermal crosstalk between the dies902and dies904.

Example System

FIG.10illustrates a computing system implemented with one or more integrated circuit structures that implement the cooling techniques disclosed herein, in accordance with some embodiments of the present disclosure. As can be seen, the computing system2000houses a motherboard2002. The motherboard2002may include a number of components, including, but not limited to, a processor2004and at least one communication chip2006, each of which can be physically and electrically coupled to the motherboard2002, or otherwise integrated therein. As will be appreciated, the motherboard2002may be, for example, any printed circuit board, whether a main board, a daughterboard mounted on a main board, or the only board of system2000, etc.

The communication chip2006also may include an integrated circuit die packaged within the communication chip2006. In accordance with some such example embodiments, the integrated circuit die of the communication chip includes one or more integrated circuit structures or devices as variously described herein. As will be appreciated in light of this disclosure, note that multi-standard wireless capability may be integrated directly into the processor2004(e.g., where functionality of any chips2006is integrated into processor2004, rather than having separate communication chips). Further note that processor2004may be a chip set having such wireless capability. In short, any number of processor2004and/or communication chips2006can be used. Likewise, any one chip or chip set can have multiple functions integrated therein.

FURTHER EXAMPLE EMBODIMENTS

An integrated circuit package comprising: a substrate; a first die and a second die above the substrate; a vapor chamber above the first die and the second die, the vapor chamber including a wicking material, a vapor space above the wicking material, and a structure that extends through the vapor space and that defines a first section of the vapor space and a second section of the vapor space, the structure to at least partly restrict flow of vapor from the first section of the vapor space to the second section of the vapor space.

The integrated circuit package of Example 1, wherein the first section of the vapor space is above the first die, and the second section of the vapor space is above the second die.

The integrated circuit package of any of Examples 1-2, wherein the structure does not extend through the wicking material.

The integrated circuit package of any of Examples 1-2, wherein the structure extends into the wicking material, and at least partly restricts flow of liquid from a first section of the wicking material to a second section of the wicking material.

The integrated circuit package of any of Examples 1-4, wherein: the vapor chamber has a bottom plate facing the first and second dies, a top plate opposite the bottom plate, and at least a first sidewall and an opposing second sidewall between the top and bottom plates; and the structure extends from the top plate, and is between the first sidewall and the second sidewall.

The integrated circuit package of Example 5, wherein: a first end of the structure faces the first sidewall and an opposite second end of the structure faces the second sidewall; and the first end of the structure does not extend to the first sidewall, such that the first section of the vapor space and the second section of the vapor space are connected through a space between the first end of the structure and the first sidewall.

The integrated circuit package of Example 5, wherein: a first end of the structure is attached to the first sidewall and an opposite second end of the structure is attached to the second sidewall.

The integrated circuit package of any of Examples 5-7, further comprising one or more posts between the top and bottom plates.

The integrated circuit package of any of Examples 1-8, wherein the structure comprises a baffle.

The integrated circuit package of Example 9, wherein the baffle comprises metal.

The integrated circuit package of any of Examples 1-10, further comprising: a heat sink above the vapor chamber.

The integrated circuit package of any of Examples 1-11, further comprising: a third die above the substrate, wherein the vapor chamber includes another structure that extends through the vapor space, the another structure to at least partly restrict flow of vapor from the second section of the vapor space to a third section of the vapor space, and wherein the second section of the vapor space is above the second die, and the third section of the vapor space is above the third die.

The integrated circuit package of any of Examples 1-11, further comprising: a third die above the substrate, wherein the first section of the vapor space is above the first die and the third die, and the second section of the vapor space is above the second die.

The integrated circuit package of any of Examples 1-13, wherein the vapor chamber is within a heat spreader structure that is thermally coupled to the first and second die.

The integrated circuit package of Example 14, further comprising a heat sink thermally bonded to an outer surface of the heat spreader structure.

A motherboard, wherein the integrated circuit package of any of Examples 1-15 is attached to the motherboard.

A computing system comprising the integrated circuit package of any of Examples 1-16.

An integrated circuit package comprising: a substrate; a first die and a second die above the substrate; a vapor chamber above the first die; an anisotropic thermal material above the second die; and a heat sink above one or both of the vapor chamber and the anisotropic thermal material; wherein the anisotropic thermal material has substantially higher thermal conductivity in a direction of the heat sink than a thermal conductivity in a direction of at least a section of the vapor chamber.

The integrated circuit package of Example 18, wherein the anisotropic thermal material has thermal conductivity of at least 1500 W/m-° K in the direction of the heat sink, and a thermal conductivity of at most 15 W/m-° K in the direction of the vapor chamber.

The integrated circuit package of any of Examples 18-19, wherein the anisotropic thermal material comprises Pyrolytic Graphite material.

The integrated circuit package of any of Examples 18-20, wherein the anisotropic thermal material comprises parallel sheets of hexagonal arrays carbon atoms, and wherein the direction of the heat sink is along a length of the parallel sheets, and the direction of at least the section of the vapor chamber is perpendicular to a plane of the parallel sheets.

The integrated circuit package of any of Examples 18-22, wherein: at least the section of the vapor chamber is a first section of the vapor chamber; and the anisotropic thermal material has substantially higher thermal conductivity in a direction of a second section of the vapor chamber; the first section of the vapor chamber is above the first die; and the second section of the vapor chamber is not above any die.

The integrated circuit package of Example 22, further comprising: a third die, wherein the anisotropic thermal material has substantially higher thermal conductivity in the direction of the heat sink than a thermal conductivity in a direction of a third section of the vapor chamber, and wherein the third section of the vapor chamber is above the third die.

The integrated circuit package of any of Examples 18-23, wherein the vapor chamber has an opening, and the anisotropic thermal material is within the opening in the vapor chamber.

The integrated circuit package of any of Examples 18-24, wherein the vapor chamber is in a loop around the opening.

The integrated circuit package of any of Examples 18-25, wherein the vapor chamber is within a heat spreader structure that is thermally coupled to the first and second die.

A motherboard, wherein the integrated circuit package of any of Examples 18-26 is attached to the motherboard.

A computing system comprising the integrated circuit package of any of Examples 18-27.

An apparatus comprising: a substrate; a first die and a second die above the substrate; and a vapor chamber including a first section above the first die, a second section above the second die, and a baffle to at least partly separate the first section from the second section.

The apparatus of Example 29, wherein the vapor chamber comprises; a wick structure, and a vapor space above the wick structure, wherein the baffle extends through the vapor space, without extending through the wick structure.

The apparatus of Example 29, wherein the vapor chamber comprises: a wick structure, and a vapor space above the wick structure, wherein the baffle extends through the vapor space and the wick structure.

The apparatus of any of Examples 29-31, wherein the vapor chamber comprises: a wick structure, and a vapor space above the wick structure, wherein the vapor space is at least partly separated into the first section and the second section, without any separation in the wick structure.

The apparatus of any of Examples 29-32, wherein the baffle comprises: a first section; a second section that is at an angle higher than 100 degrees with respect to the first section; and a third section that is at an angle higher than 100 degrees with respect to the first section.

The apparatus of Example 33, wherein the first section of the baffle is between the second and third sections, and is substantially parallel to a side of the first die.

The apparatus of any of Examples 29-34, wherein the vapor chamber is within a heat spreader structure that is thermally coupled to the first and second die.

A motherboard, wherein the integrated circuit package of any of Examples 29-35 is attached to the motherboard.

A computing system comprising the integrated circuit package of any of Examples 29-36.