WO2017019015A1

WO2017019015A1 - Heat dissipation for dies

Info

Publication number: WO2017019015A1
Application number: PCT/US2015/042260
Authority: WO
Inventors: Sergio ESCOBAR VARGAS; Niru Kumari; Cullen E. Bash
Original assignee: Hewlett Packard Enterprise Development Lp
Priority date: 2015-07-27
Filing date: 2015-07-27
Publication date: 2017-02-02

Abstract

A first heat dissipation conduit includes a channel to carry heated cooling fluid through a first die, and a wick structure to carry cooling fluid through the first die. A second heat dissipation conduit of the plurality of heat dissipation conduits is to carry at least one of cooling fluid or heated cooling fluid between the first die and a second die.

Description

HEAT DISSIPATION FOR DIES

Background

[0001 ] During operation, an electronic device can produce heat. A heat dissipation device can be provided to dissipate heat from a component (such as a processor or other component) in the electronic device. The heat dissipation device can include a heat sink that is thermally contacted to the heat-producing component.

Brief Description Of The Drawings

[0002] Some implementations of the present disclosure are described with respect to the following figures.

[0003] Fig. 1 is a cross-sectional view of an example die including heat dissipation conduits according to some implementations.

[0004] Fig. 2 is a top view of an example die including heat dissipation conduits according to some implementations.

[0005] Fig. 3 is a cross-sectional view of an example stack of dies including heat dissipation conduits according to some implementations.

[0006] Figs. 4 and 5 are sectional views of example integrated circuit assemblies including a stack of dies and a heat dissipation subsystem according to some implementations.

[0007] Fig. 6 is a flow diagram of a process of providing an example heat dissipation subsystem according to some implementations.

Detailed Description

[0008] Electronic devices can include integrated circuit (IC) components.

Examples of electronic devices include computers (e.g. desktop computers, tablet computers, notebook computers, etc.), smartphones, personal digital assistants (PDAs), game appliances, wearable devices (e.g. smart watches, electronic eyeglasses, etc.), vehicles, and so forth.

[0009] An IC component can refer to a component in which circuitry (including, as examples, any or some combination of transistors, diodes, capacitors, resistors, electrically conductive traces, optical elements, and so forth) can be formed on a substrate (or substrates). Heat can be generated by the circuitry during operation of the circuitry.

[0010] IC components can be packaged in three-dimensional (3D)

configurations. An IC component packaged in a 3D configuration can include a stack of dies, in which one die can be provided over (stacked) another die. An IC component with a stacked arrangement of dies can improve integration, reduce physical footprint, and/or improve performance, in some examples.

[001 1 ] A die can refer to any block that includes a substrate on which functional elements can be formed. In some examples, the functional elements formed on the substrate of a die can include circuitry. For example, the circuitry of a die can form a microprocessor or a core of a microprocessor, a programmable gate array, an application-specific integrated circuit (ASIC) component, a memory, an input/output (I/O) component, and so forth, or any combination of the foregoing. In other examples, functional elements of dies can include heat dissipation elements, as discussed further below.

[0012] Heat dissipation challenges can restrict the size, the number of dies that can be stacked in a stack of dies, and/or the arrangement of dies in the stack (e.g. memory dies on top and processor dies on the bottom, or vice versa). High power dies, such as dies including microprocessors or microprocessor cores, can produce a relatively large amount of heat that may be difficult to dissipate if such high power dies are embedded in the inner levels of a stack of dies. Dies in the inner levels of the stack of dies can be difficult to reach for purposes of heat dissipation. When overheating occurs in an IC component, the frequency and/or voltage of the IC component (or a portion of the IC component) may have to be reduced, which can reduce overall performance. Alternatively, a setting of a cooling subsystem may have to be increased to cool the overheated IC component, which can consume additional energy and increase the cost of operation.

[0013] In accordance with some implementation of the present disclosure, a heat dissipation subsystem can include heat dissipation conduits for carrying heated fluids (as heated by circuitry in a stack of dies) and for carrying cooling fluids back to the circuitry to cool the circuitry. In some implementations, a first heat dissipation conduit can be included in a die to carry cooling fluid and heated cooling fluid through the die. A second heat dissipation conduit can cross through multiple dies of the stack of dies to carry heated cooling fluid and cooling fluid between dies of the stack of dies.

[0014] Fig. 1 is a cross-sectional view of an example die 100 that can be used in a stack of dies according to some implementations of the present enclosure. The die 100 has a substrate 102, which can be formed of a semiconductor material (e.g. silicon), an electrically insulating material, or other type of material. The die 100 further includes circuitry 104 that can be formed on the substrate 102 (at an upper surface 1 14). As examples, the circuitry 104 can include a microprocessor, a microprocessor core, an I/O component, a memory, an optical element, and so forth. Fig. 1 also shows various heat dissipation conduits 106 that can extend through the substrate 102 of the die 100. The heat-dissipation conduits 106 are referred to as through-die heat dissipation conduits, since they extend from one side of the substrate 102 of the die 100 to the other side of the substrate 102.

[0015] Each heat dissipation conduit 106 can include a channel 108 to carry heated cooling fluid (such as in vapor form) and a wick structure 1 10 to carry cooling fluid (such as in liquid form). The wick structure 1 10 of a heat dissipation conduit 106 can be formed on an inner wall 1 12 of the heat dissipation conduit 106. For example, the material that forms the wick structure 1 10 can be deposited or otherwise attached to the inner wall 1 12 of the heat dissipation conduit 106. In other examples, the wick structure 1 10 can be formed on an outer wall of a heat

dissipation conduit, or can be a porous tube-like structure placed in the middle of the channel with vapor space surrounding the tube-like structure, or can include any other structure that has porous media with pores to provide for communication of the cooling fluid by capillary effect.

[0016] In some examples, a heat dissipation conduit 106 can also be referred to as a "microchannel." A microchannel can refer to a conduit (for carrying fluids) that has a hydraulic diameter that is less than 1 millimeter, in some examples. The hydraulic diameter, Dh, of a channel is expressed as Dh = 4^*(cross sectional channel area)/(wetted perimeter of the channel). In other examples, the microchannel can have other dimensions.

[0017] The wick structure 1 10 can include an arrangement of elements that define pathways to allow for communication of a fluid by capillary effect. In some examples, the wick structure 1 10 can include nanoparticles or a nanomesh.

Nanoparticles can include elements of a material that have dimensions on a nanometer scale, e.g. less than 100 nanometers. A nanomesh can include a crossing arrangement of elements of a material, where the elements have

dimensions on a nanometer scale. In some examples, the material of the

nanoparticles or nanomesh can include silicon dioxide. In other examples, other materials can be used to form the wick structure 1 10.

[0018] Although Fig. 1 shows a specific number of heat dissipation conduits 106 extending through the die 100, it is noted that in other examples, a different number (one or greater than one) of heat dissipation conduits 106 can be provided in the die 100.

[0019] Also, although Fig. 1 shows the die 100 with circuitry 104, it is noted that in other examples, the die 100 can include just a heat dissipation conduit 106 (or multiple heat dissipation conduits 106) without any operational circuitry.

[0020] Fig. 2 is a top view of the die 100 according to some implementations. The cross-sectional view shown in Fig. 1 is along section 1 -1 in Fig. 2. The top view of Fig. 2 also shows circuitry 104 arranged on the substrate 102 of the die 100. [0021 ] In examples according to Fig. 2, in addition to through-die heat dissipation conduits 106 that extend through the die 100 along a first axis 202, the die 100 can also include additional through-die heat dissipation conduits 1 16 that extend along a second axis 204 of the die 100. In some examples, the second axis 204 can be perpendicular to the first axis 202. More generally, the second axis 204 can be angled with respect to the first axis 202, such as in arrangements where heat dissipation conduits extend along a diagonal direction. Also, instead of extending along a straight line, a through-die heat dissipation conduit 106 or 1 16 can also bend, such as along a curved path or at an angle.

[0022] Each through-die heat dissipation conduit 1 16 includes a channel and wick structure that are similar to the channel 108 and wick structure 1 10 of a through-die heat dissipation conduit 106. A heat dissipation conduit 1 16 is connected to a heat dissipation conduit 106 such that they can communicate cooling fluid and heated cooling fluid with each other.

[0023] In addition to heat dissipation conduits 106 and 1 16 that are generally parallel to an upper surface 1 14 of the substrate 102 of the die 100, the die 100 can also include heat dissipation conduits 206 that each extends in a direction that is generally perpendicular to the top surface 1 14 of the substrate 102. Thus, in a stack of dies that are arranged one over another, the heat dissipation conduits 206 can extend along the vertical axis of the stack of dies. Each heat dissipation conduit 206 can be referred to as an inter-die heat dissipation conduit, since the heat dissipation conduit 206 is arranged to carry heated cooling fluid and cooling fluid between dies in a stack of dies.

[0024] As shown in Fig. 2, each inter-die heat dissipation conduit 206 is connected by a connecting element 208 to a respective heat dissipation conduit 106. Although not shown in Fig. 2, it is noted that in some examples, an inter-die heat dissipation conduit 206 can also be connected by a connecting element 208 to a respective heat dissipation conduit 1 16. The connecting element 208 is configured to carry fluids (cooling fluid and heated cooling fluid) between the inter-die heat dissipation conduit 206 and the respective through-die heat dissipation conduit 106 or 1 16. Note that, in some examples, each inter-die heat dissipation conduit 206 and connecting element 208 can include a channel and wick structure similar to the channel 108 and wick structure 1 10 shown in Fig. 1 .

[0025] In an arrangement according to Fig. 2, heated cooling fluid can be carried by the through-die heat dissipation conduits 106 and 1 16 through the respective connecting elements 208 to corresponding inter-die heat dissipation conduits 206. Also, cooling fluid can be carried through the through-die heat dissipation conduits 106 and 1 16 and the inter-die heat dissipation conduits 206 and connecting elements 208.

[0026] In other examples, instead of using inter-die heat dissipation conduits 206 with a channel and wick structure as noted above, a first subset of the inter-die heat dissipation conduits 206 can include a porous media to carry cooling fluid by capillary effect (this first subset of the inter-die heat dissipation conduits 206 do not have channels to carry heated cooling fluid), and a second subset of the inter-die heat dissipation conduits 206 has a channel to carry heated cooling fluid (this second subset of the inter-die heat dissipation conduits 206 do not have porous media to carry cooling fluid). The first subset of the inter-die heat dissipation conduits 206 can be referred to as supply inter-die heat dissipation conduits for supplying cooling fluid, and the second subset of the inter-die heat dissipation conduits 206 can be referred to as return inter-die heat dissipation conduits 206 for returning heated cooling fluid.

[0027] Fig. 3 shows an example stack of dies 300 that includes a first die 100-1 and a second die 100-2. The first die 100-1 can include a through-die heat dissipation conduit 106 and an inter-die conduit 206-1 that is connected by a connecting element 208 to the through-die heat dissipation conduit 106. The second die 100-2 includes an inter-die heat dissipation conduit 206-2 that is aligned with the inter-die heat dissipation conduit 206-1 of the first die 100-1 . The inter-die heat dissipation conduits 206-1 and 206-2 collectively can form an inter-die heat dissipation conduit for carrying cooling fluid heated cooling fluid across the stack of dies 300. [0028] In some examples, each of the first die 100-1 and second die 100-2 can include circuitry 104 that can produce heat during operation of the circuitry. In other examples, just one of the dies 100-1 and 100-2 can include the circuitry 104.

[0029] During operation, cooling fluid can be carried by the inter-die heat dissipation conduits 206-1 and 206-2 for communication through the connecting element 208 to the through-die heat dissipation conduit 106. More specifically, the cooling fluid is communicated through the wick structures of the inter-die heat dissipation conduits 206-1 and 206-2, the connecting element 208, and the through- die heat dissipation conduit 106.

[0030] The through-die heat dissipation conduit 106 is proximate the circuitry 104 such that the cooling fluid in the through-die heat dissipation conduit 106 can cool the circuitry 104. Cooling fluid heated by the circuitry 104 is then carried through the channel of the through-die heat dissipation conduit 106, for communication through the channel of the connecting element 208 to the channel of the inter-die heat dissipation conduit 206-1 . The heated cooling fluid can then be carried away from the stack of dies 300 through the inter-die heat dissipation conduit 206-1 .

[0031 ] In other examples, as discussed further above, instead of providing an inter-die heat dissipation conduit 206 with a wick structure and channel, a supply inter-die heat dissipation conduit and a return inter-die heat dissipation conduit can be provided to carry cooling fluid and heated cooling fluid, respectively.

[0032] Fig. 4 is a cross-sectional view of an example IC component 400 that includes a heat dissipation subsystem according to some implementations of the present disclosure. The heat dissipation subsystem includes through-die heat dissipation conduits (e.g. 106 and/or 1 16 as discussed above) and inter-die heat dissipation conduits 206, and a heat sink 402 that has fins 404 to assist in heat dissipation. An airflow can be generated through the channels between the fins 404 to carry heat away from the heat sink 402. In some examples, an airflow can be produced by an airflow generator (e.g. a fan). In other examples, instead of or in addition to the heat sink 402, other external cooling subsystems can be employed, such as a liquid cold plate and so forth.

[0033] The IC component 400 includes a package 406 (that has an outer housing) that defines an inner chamber 408 in which a stack of dies 410 can be provided. The stack of dies 410 is contained in the inner chamber 408 of the package 406. The IC component 400 includes a substrate 416 on which the package 406 is mounted. The stack of dies 410 is also mounted on an upper surface 418 of the substrate 416. Electrical communication between the stack of dies 410 and electrically conductive traces or other conductive elements of the substrate 416 can be provided through solder bumps 424 between the bottom side of the stack of dies 410 and the substrate 416. The solder bumps can be formed of an electrically conductive material, such as copper, another type of metal, or any other type of electrically conductive material.

[0034] The heat dissipation subsystem also includes a wick structure 412. The wick structure 412 can have a similar arrangement as the wick structure 1 10, or can have a different arrangement from the wick structure 1 10 (such as a different material and/or different pore characteristic of porous media). The wick structure 412 can be formed on inner side walls 414 of the package 406. The wick structure 412 extends along the inner side walls 414 of the package 406. The wick structure 412 also extends at least partially along the upper surface 418 of the substrate 416. Cooling fluid can flow along directions indicated by arrows 413.

[0035] During operation of the stack of dies 410, heated cooling fluid is carried by through-die heat dissipation conduits 106 (and 1 16 shown in Fig. 2) and connecting elements 208 to inter-die heat dissipation conduits 206. The heated cooling fluid is carried by the inter-die heat dissipation conduits 206 towards an inner upper wall 420 of the package 406. The heated cooling fluid in the inter-die heat dissipation conduits 206 includes vaporized heated cooling fluid that can rise towards the upper inner wall 420 of the package 406. The heat sink 402 is thermally contacted to the top surface of the package 406, and thus the heat sink 402 can provide cooling along the top portion of the package 406. [0036] When the vaporized heated cooling fluid reaches the upper inner wall 420 of the package 406, condensation occurs (the location where condensation occurs is indicated by dotted lines 422). The condensation is caused by the cooling provided by the heat sink 402. The condensed cooled fluid is returned by the wick structure 412 along the inner side walls 414 of the package 406 and along the upper surface 418 of the substrate 416 (as indicated by arrows 413).

[0037] The cooling fluid carried by the wick structure 412 reaches the bottom part of the stack of dies 410. In some examples, the bottom part of the stack of dies 410 can include solder bumps 424 to allow for electrical interconnection between the stack of dies 410 and the substrate 416. The solder bumps 424 can be arranged in close proximity to each other, such that the solder bumps can also provide a capillary effect for the communication of cooling fluid towards the inter-die heat dissipation conduits 206. The cooling fluid is then carried by the wick structures of the inter-die heat dissipation conduits 206 through the stack of dies 410, with the cooling fluid communicated through respective connecting elements 208 to the through-die heat dissipation conduits 106 shown in Fig. 4.

[0038] The cooling fluid is carried by the through-die heat dissipation conduits 106 (and 1 16 depicted in Fig. 2) to respective regions of each of the dies in the stack of dies 410, to provide cooling of respective circuitry during operation of the stack of dies 410. The cooling fluid is heated by the heat produced by the circuitry, with the heated cooling fluid returned through respective channels of the through-die heat dissipation conduits 106, 1 16 back towards the inter-die heat dissipation conduits 206. The heated cooling fluid then rises through respective channels of the inter-die heat dissipation conduits 206, towards the upper inner wall 420 of the package 406 for condensation (422).

[0039] As further shown in Fig. 4, the lower surface 426 of the substrate 416 is provided with various solder bumps 430 to allow the IC component 400 to be electrically interconnected to another structure, such as a main circuit board. [0040] In some examples, the cooling fluid that is carried by the various heat dissipation conduits (106, 1 16, 206) can include a cooling fluid that is electrically non-conductive. An example of an electrically non-conductive cooling fluid is a fluorocarbon-based fluid. Examples of fluorocarbon-based fluids include any one or combination of the following: perfluorohexane, perfluoro(2-butyl-tetrahydrofurane), or perfluorotripentylamine. In other examples, other types of cooling fluids can be employed. Note that the wick structure and its material and fluid properties of the cooling fluid work together to generate capillary force to drive the cooling fluid. In other examples, instead of using a fluorocarbon-based fluid, a non-conductive oil can be used.

[0041 ] In some examples, the solder bumps 424 can be coated with a dielectric layer to avoid any short-circuiting issues associated with provision of cooling fluids around the solder bumps 424.

[0042] Fig. 5 shows an IC component 500 that is a modified version of the IC component 400 of Fig. 4. The same reference numerals are assigned to elements of the IC component 500 that are similar to respective elements of the IC component 400.

[0043] In a stack of dies 510 of the IC component 500, inter-die layers 512 are provided between dies 100 of the stack of dies 510. Each inter-die layer 512 includes solder bumps 514, which can be used to provide electrical interconnection between the dies 100. In addition, the solder bumps 514 allow for communication of a cooling fluid by capillary effect for cooling the dies 100. The cooling fluid provided through the inter-layers 512 that are heated can be carried by the inter-die fluid dissipation conduits 206 towards the heat sink 402.

[0044] Fig. 6 is a flow diagram of a process of providing a heat dissipation subsystem for a stack of dies, according to some implementations. The process of Fig. 6 arranges (at 602) first heat dissipation conduits (e.g. 106 and/or 1 16) in dies of the stack of dies, where each of the first heat dissipation conduits include a channel to carry heated cooling fluid and a wick structure to carry cooling fluid. The process also includes arranging (at 604) second heat dissipation conduits (e.g. 206) that cross dies of the stack of dies, where each of the second heat dissipation conduits include a channel to carry heated cooling fluid between dies and a wick structure to carry cooling fluid between dies.

[0045] In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.

Claims

What is claimed is: 1 . An integrated circuit assembly comprising:

a first die comprising a heat dissipation conduit in the first die, the heat dissipation conduit comprising:

a channel to carry heated cooling fluid as heated by operation of first circuitry, and

a wick structure to carry cooling fluid to cool the first circuitry;

a second die stacked over the first die, the second die comprising second circuitry; and

an inter-die heat dissipation conduit between the first die and the second die, the inter-die heat dissipation conduit to carry at least one of a cooling fluid or a heated cooling fluid between the first and second dies.

2. The integrated circuit assembly of claim 1 , wherein the inter-die heat dissipation conduit comprises:

a channel to carry heated cooling fluid between the first and second dies, and a wick structure to carry cooling fluid between the first and second dies.

3. The integrated circuit assembly of claim 1 , wherein the first die comprises the first circuitry.

4. The integrated circuit assembly of claim 1 , further comprising a third die in thermal contact with the first die, the third die comprising the first circuitry.

5. The integrated circuit assembly of claim 1 , wherein the wick structure of the heat dissipation conduit of the first die is provided on a wall of the heat dissipation conduit of the first die.

6. The integrated circuit assembly of claim 1 , wherein the wick structure of the heat dissipation conduit of the first die comprises nanoparticles or a nanomesh.

7. The integrated circuit assembly of claim 1 , further comprising: a package including an inner chamber, wherein a stack comprising the first die and the second die is placed in the inner chamber.

8. The integrated circuit assembly of claim 7, further comprising:

a wick structure provided on a wall of the package to carry cooling fluid to the stack; and

a cooling subsystem thermally contacted to the package to cool heated cooling fluid from the inter-die heat dissipation conduit.

9. The integrated circuit assembly of claim 8, further comprising:

electrically conductive bumps to electrically connect the stack to the package, wherein the wick structure provided on the wall of the package is to carry cooling fluid to a region proximate the electrically conductive bumps, and the inter- die heat dissipation conduit is to carry cooling fluid from the region proximate the electrically conductive bumps into the stack.

10. The integrated circuit assembly of claim 1 , further comprising a layer comprising a heat dissipation conduit to carry cooling fluid, the layer provided between the first die and the second die.

1 1 . A heat dissipation apparatus comprising:

a plurality of heat dissipation conduits,

a first heat dissipation conduit of the plurality of heat dissipation conduits comprising:

a channel to carry heated cooling fluid through a first die of a stack of dies, and

a wick structure to carry cooling fluid through the first die, a second heat dissipation conduit of the plurality of heat dissipation conduits to carry at least one of cooling fluid or heated cooling fluid between dies of the stack of dies.

12. The heat dissipation apparatus of claim 1 1 , wherein the second heat dissipation conduit comprises:

a channel to carry heated cooling fluid between dies of the stack of dies, and a wick structure pr to carry cooling fluid between dies of the stack of dies.

13. The heat dissipation apparatus of claim 1 1 , further comprising:

a cooling subsystem,

wherein the second heat dissipation conduit is emit vaporized heated cooling fluid towards the cooling subsystem for cooling by the cooling subsystem, and

wherein the cooling subsystem is to cause condensation of the vaporized heated cooling fluid.

14. A method of providing a heat dissipation subsystem for a stack of dies, comprising:

arranging first heat dissipation conduits in dies of the stack of dies, each of the first heat dissipation conduits comprising a channel to carry heated cooling fluid and a wick structure to carry cooling fluid; and

arranging second heat dissipation conduits that cross dies of the stack of dies, each of the second heat dissipation conduits comprising a channel to carry heated cooling fluid between dies and a wick structure to carry cooling fluid between dies of the stack of dies.

15. The method of claim 14, further comprising:

arranging a wick structure on a wall of a package that defines a chamber in which the stack of dies is provided, the wick structure on the wall of the package to carry cooling fluid to the stack of dies.