JP2015169411A - Heat transport device and method of manufacturing thereof, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat transport efficiency of a heat transport device, in a manufacturing method thereof and electronic equipment.SOLUTION: A heat transport device 1 includes: a body 2 that comprises a cavity S; a plurality of linear structures 7 made of a carbon element and erected on a surface on the cavity S side of the body 2; a hydrophilic coating 8 that is formed on a surface of the linear structure 7; and a working fluid C1 that is held among the plurality of respective linear structures 7.

Description

  The present invention relates to a heat transport device, a manufacturing method thereof, and an electronic apparatus.

  With the advent of an advanced information society, mobile electronic devices such as smartphones and tablet terminals are spreading. Since mobile electronic devices are thinned so that they can be easily carried, heat pipes that can be easily reduced in size are being considered as heat transport devices for cooling heat-generating components such as CPUs (Central Processing Units). ing.

  A heat pipe is a heat transport device that cools a heat-generating component by the heat of vaporization of a working fluid enclosed in the pipe. One end of the pipe functions as an evaporation unit that evaporates the working fluid with the heat of the heat-generating component, and the other end of the pipe functions as a condensing unit that cools and liquefies the vapor of the working fluid.

  In addition, a wick for moving the liquid-phase working fluid from the condensing unit to the evaporating unit by capillary force is provided on the inner surface of the pipe.

  There are various types of wicks. For example, a fine groove formed on the inner surface of a pipe may be used as a wick, or a metal mesh member may be used as a wick. In addition, a porous sintered metal obtained by sintering a metal such as copper may be used as a wick.

  However, in these wicks, it is difficult to reduce the size of the heat pipe because it is difficult to miniaturize the grooves and holes through which the working fluid flows.

  Therefore, it has been studied to grow a plurality of carbon nanotubes that can be easily miniaturized on the inner surface of the pipe and to use these carbon nanotubes as wicks. In this case, the capillary force acting from the carbon nanotubes becomes a driving force for moving the liquid-phase working fluid, and it can be expected that the liquid-phase working fluid flows from the condensing part toward the evaporation part.

Special table 2009-535598 Japanese Utility Model Publication No. 5-45465 JP 2010-121867 A

  However, since the surface of the carbon nanotube is hydrophobic and the liquid working fluid is repelled on the surface, it becomes difficult to flow the working fluid from the condensing part to the evaporation part, and the heat transport efficiency of the heat pipe is reduced. Resulting in.

  Therefore, the disclosed technique aims to improve the heat transport efficiency of the heat transport device in the heat transport device, the manufacturing method thereof, and the electronic apparatus.

  According to one aspect of the following disclosure, a main body having a cavity, a plurality of carbon element linear structures standing on the cavity-side surface of the main body, and a surface of the linear structure are formed. A heat transport device having a hydrophilic coating and a working fluid retained between each of the plurality of linear structures is provided.

  According to another aspect of the disclosure, a step of growing a linear structure of a plurality of carbon fibers on a surface on the cavity side of a surface of a main body having a cavity, and a surface of the linear structure Further, there is provided a method for manufacturing a heat transport device, which includes a step of forming a hydrophilic film and a step of supplying a working fluid into the cavity.

  Furthermore, according to another aspect of the disclosure, the heat transport device and a heat-generating component thermally connected to the heat transport device, the heat transport device including a body having a cavity, the cavity A plurality of carbon element linear structures standing on the surface of the main body, a hydrophilic coating formed on the surface of the linear structure, and each of the plurality of linear structures An electronic device comprising a retained working fluid is provided.

  According to the following disclosure, since a hydrophilic coating is formed on the surface of the linear structure of carbon element, the flow of the working fluid is smoothed by the capillary force acting on the working fluid from the coating, and the heat of the heat transport device Transport efficiency is improved.

FIG. 1 is a cross-sectional view of the heat transport device according to the first embodiment. FIG. 2 is an enlarged cross-sectional view of the pipe according to the first embodiment cut in the longitudinal direction. FIG. 3 is an enlarged cross-sectional view of each carbon nanotube in the first embodiment. FIG. 4 is an enlarged plan view of the inner surface of the pipe according to the first embodiment. FIG. 5 is a cross-sectional view in the short direction of the pipe according to the first embodiment. FIG. 6 is a schematic cross-sectional view for explaining the operation of the heat transport device according to the first embodiment. FIG. 7 is a perspective view in the middle of manufacturing the heat transport device according to the first embodiment. FIGS. 8A and 8B are enlarged cross-sectional views (part 1) in the course of manufacturing the heat transport device according to the first embodiment. FIGS. 9A and 9B are enlarged cross-sectional views (part 2) in the middle of manufacturing the heat transport device according to the first embodiment. FIG. 10 is a cross-sectional view in the short-side direction of the heat transport device according to the first embodiment. FIG. 11 is a longitudinal sectional view of the heat transport device according to the first embodiment. 12 (a) and 12 (b) are enlarged plan views of the inner surface of the pipe in the course of manufacturing the heat transport device according to the first embodiment. FIG. 13 is a cross-sectional view of the heat transport device according to the second embodiment. FIG. 14 is an enlarged cross-sectional view of the inner surface of the pipe of the heat transport device according to the second embodiment. FIG. 15 is a schematic cross-sectional view in the longitudinal direction of the heat transport device according to the third embodiment. FIG. 16 is a schematic cross-sectional view for explaining the operation of the heat transport device according to the third embodiment. FIG. 17 is a cross-sectional view schematically showing a carbon nanotube growth method in which the length sequentially changes in the third embodiment. FIG. 18 is a schematic plan view of an electronic apparatus according to the fourth embodiment. FIG. 19 is a cross-sectional view of the semiconductor device according to the fifth embodiment. FIG. 20 is a plan view when the first vapor chamber according to the fifth embodiment is cut along the line II in FIG. FIG. 21 is a plan view when the second vapor chamber according to the fifth embodiment is cut along the line II-II in FIG. 19. FIG. 22A is a schematic plan view of a first vapor chamber according to the fifth embodiment, and FIG. 22B is a cross-sectional view taken along the line III-III in FIG. FIGS. 23A and 23B are sectional views (part 1) in the middle of manufacturing the first vapor chamber according to the fifth embodiment. FIGS. 24A and 24B are cross-sectional views (part 2) in the middle of manufacturing the first vapor chamber according to the fifth embodiment. FIGS. 25A and 25B are cross-sectional views (part 3) in the middle of manufacturing the first vapor chamber according to the fifth embodiment. 26A and 26B are cross-sectional views (part 4) in the middle of manufacturing the first vapor chamber according to the fifth embodiment. FIG. 27 is a first cross-sectional view of the semiconductor device according to the fifth embodiment during manufacture. FIG. 28 is a cross-sectional view (part 2) of the semiconductor device according to the fifth embodiment in the middle of manufacture. FIG. 29 is a cross-sectional view (No. 3) in the middle of manufacturing the semiconductor device according to the fifth embodiment.

  Each embodiment will be described below with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a cross-sectional view of the heat transport device according to the present embodiment.

  The heat transport device 1 is a heat pipe accommodated in a mobile electronic device such as a smartphone or a tablet terminal, and includes a straight pipe 2. The pipe 2 is an example of a main body, and the space inside thereof is provided as a cavity S in which a working fluid such as water or ethanol is held. The inside of the cavity S is decompressed, and the wick 3 is provided on the inner surface 2x of the pipe 2 exposed to the cavity S.

  The dimensions of the pipe 2 are not particularly limited. In this example, the length of the pipe 2 is about 10 cm, and the inner diameter of the pipe 2 is about 1 mm.

  One end of the pipe 2 is provided as an evaporation unit 2a that evaporates the working fluid. On the other hand, the other end of the pipe 2 is provided as a condensing part 2b for liquefying the vaporized working fluid.

  A heat-generating component 11 such as a CPU (Central Processing Unit) is thermally connected to the evaporation unit 2 a via a heat conductive sheet 10, and the working fluid is vaporized by the heat of the heat-generating component 11.

  In addition, the heat conductive sheet 10 is a graphite sheet with favorable heat conductivity, for example.

  FIG. 2 is an enlarged cross-sectional view of the pipe 2 cut in the longitudinal direction.

  As shown in FIG. 2, a plurality of carbon nanotubes 7 are erected on the inner surface 2x of the pipe 2 as the wick 3 described above, and a liquid-phase working fluid C1 is held between the carbon nanotubes 7. The

  The carbon nanotube 7 is an example of a linear structure of carbon elements.

  The size of each carbon nanotube 7 is not particularly limited, but in this example, the length L is about 150 μm to 200 μm, and the thickness Q is about 10 nm to 30 nm. The interval P between the adjacent carbon nanotubes 7 is, for example, about 50 nm to 100 nm.

  FIG. 3 is an enlarged cross-sectional view of each carbon nanotube 7.

  As shown in FIG. 3, a granular catalyst metal layer 6 such as iron is provided on the inner surface 2 x of the pipe 2, and each carbon nanotube 7 grows on the catalyst metal layer 6.

An alumina (Al ₂ O ₃ ) film is formed as a hydrophilic film 8 on each of the surface of the carbon nanotube 7 and the inner surface 2x.

  In this example, the coating 8 is removed from the tip 7a of the carbon nanotube 7, and the coating 8 is left from the root 7b of the carbon nanotube 7 to the inner surface 2x.

  Thereby, the root 7 b can be hydrophilized with the coating 8 while the hydrophobic carbon nanotubes 7 are exposed to the tip 7 a.

  Further, since the base 7b is reinforced by the coating 8, the carbon nanotube 7 behaves as an elastic body having the tip 7a as a free end, and is elastically deformable in the direction of the arrow X while using the base 7b as a fulcrum.

  FIG. 4 is an enlarged plan view of the inner surface 2x.

  As shown in FIG. 4, a plurality of stripe regions R extending from the evaporation part 2a (see FIG. 1) to the condensing part 2b are provided on the inner surface 2x at intervals.

  The stripe region R is a region where the carbon nanotubes 7 are erected, and the carbon nanotubes 7 are not erected in the region between the adjacent stripe regions R, and the region has a stripe shape in which a liquid-phase working fluid flows. Served as channel D.

  Thereby, compared with the case where the channel D is not provided, the liquid-phase working fluid can be smoothly transmitted through the inner surface 2x. In the case where the flow of the working fluid is smooth even without the channel D, carbon nanotubes may be provided on the entire inner surface 2x without providing the stripe region R.

  Further, the width W1 in the short direction of the stripe region R is not particularly limited. In the present embodiment, the width W1 is set to 150 μm to 200 μm.

  Further, the width W2 in the short direction of the channel D is not particularly limited, but in this example, the width W2 is set to 10 μm or less.

  The upper limit of the width W2 is 10 μm because when the wick 3 is formed of a material other than carbon nanotubes, the size of the channel through which the liquid-phase working fluid flows is approximately 20 μm or more. This is to facilitate the miniaturization of the device 1.

  For example, when a groove is formed as a wick on the inner surface 2x, the width of the groove is about 0.1 mm to 1 mm. Further, when the metal mesh member is a wick, the size of the mesh is 50 μm to 100 μm, and when the porous sintered metal is a wick, the hole of the sintered metal hole is 25 μm to 250 μm. In any of these cases, the size of the groove, mesh, and hole is larger than the width W2 according to the present embodiment.

  FIG. 5 is a cross-sectional view of the pipe 2 in the short direction.

  As shown in FIG. 5, the pipe 2 is circular in cross section, and the carbon nanotubes 7 are erected on the inner surface 2x of the pipe 2 excluding the channel D.

  Next, the operation of the heat transport device 1 will be described.

  FIG. 6 is a schematic cross-sectional view for explaining the operation of the heat transport device 1.

  Under actual use, while the evaporator 2a is heated by the heat generating component 11, the temperature of the condenser 2b is maintained at a temperature lower than that of the evaporator 2a. Each flow of the gaseous working fluid C2 is generated.

  Among these, the flow of the liquid-phase working fluid C1 is generated by the capillary force acting on the working fluid C1 from each carbon nanotube 7. Then, the working fluid C1 flows from the condensing unit 2b to the evaporating unit 2a while traveling along the inner surface 2x and the channel D (see FIG. 4).

  At this time, in this embodiment, since the hydrophilic coating 8 (see FIG. 3) is formed on the surface of each carbon nanotube 7, the liquid-phase working fluid C1 smoothly flows between the carbon nanotubes 7 and is condensed. The working fluid C1 can flow quickly from the part 2b to the evaporation part 2a.

  The liquid-phase working fluid C1 that has reached the evaporation section 2a is vaporized by the heat of the heat generating component 11 to become a gas phase, and flows from the evaporation section 2a toward the condensation section 2b.

  Here, the coating 8 is not formed on the tip 7a of each carbon nanotube 7, and the hydrophobicity of the tip 7a is maintained. Therefore, the gas-phase working fluid C2 flows through the pipe 2 while being repelled by the tip 7a, and the working fluid C2 can flow quickly from the evaporator 2a toward the condenser 2b.

  Further, since the carbon nanotubes 7 are bent as shown in FIG. 6 by the force received from the gas-phase working fluid C2, the flow path through which the gas-phase working fluid C2 flows is expanded. As a result, the resistance that the gas-phase working fluid C2 receives from each carbon nanotube 7 is reduced, so that the pressure loss of the working fluid C2 is reduced, and the flow of the working fluid C2 becomes smoother.

  Even if the carbon nanotubes 7 are bent in this way, the carbon nanotubes 7 reinforced with the coating 8 behave like elastic bodies, so that when the flow of the working fluids C1 and C2 is stopped, the carbon nanotubes 7 are restored to the original state. To return to the upright state on the inner surface 2x.

  The gas-phase working fluid C2 that has reached the condensing unit 2b is cooled in the condensing unit 2b and liquefied to become the liquid-phase working fluid C1, and the working fluid circulates in the pipe 2.

  According to the present embodiment described above, since the hydrophilic coating 8 is formed on the surface of the carbon nanotube 7 as shown in FIG. 3, the flow of the liquid-phase working fluid C1 becomes smooth, and the heat transport device The heat transport efficiency of 1 is improved.

  Further, by removing the coating 8 from the tip 7a of the carbon nanotube 7, the hydrophobic tip 7a can repel the gas-phase working fluid C2, and the flow of the working fluid C2 is promoted to further increase the heat transport efficiency. Can be improved.

  Next, the manufacturing method of the heat transport device according to the present embodiment will be described with reference to FIGS.

  FIG. 7 is a perspective view in the middle of manufacturing the heat transport device according to the present embodiment. Moreover, FIGS. 8-9 is an expanded sectional view in the middle of manufacture of the heat transport device which concerns on this embodiment. Further, FIG. 10 is a cross-sectional view in the short direction of the heat transport device according to the present embodiment, and FIG. 11 is a cross-sectional view in the longitudinal direction thereof.

  7 to 11, the same elements as those in FIGS. 1 to 6 are denoted by the same reference numerals as those in FIGS. 1 to 6, and the description thereof is omitted below.

  First, as shown in FIG. 7, a copper half 2y formed by dividing the pipe 2 in the longitudinal direction is prepared.

  Next, as shown in FIG. 8A, an iron layer is formed as a catalytic metal layer 6 on the inner surface 2x of the half 2y by sputtering to a thickness of about 2.5 nm.

  The material of the catalyst metal layer 6 is not limited to iron. For example, any of iron, cobalt, nickel, gold, silver, and platinum, or an alloy containing any of these can be used as the material of the catalytic metal layer 6.

Further, a base layer may be formed on the inner surface 2x before the catalyst metal layer 6 is formed. Examples of the material for the underlayer include molybdenum, titanium, hafnium, zirconium, niobium, vanadium, aluminum, tantalum nitride (TaN), and titanium silicide (TiSi _x ). Furthermore, any of alumina, tantalum, tungsten, copper, gold, platinum, palladium, titanium oxide (TiO _x ), and titanium nitride (TiN) may be used as the material for the underlayer.

  FIG. 12A is an enlarged plan view of the inner surface 2x after the completion of this step.

  As shown in FIG. 12A, in this example, the catalytic metal layer 6 is formed only in the stripe region R by patterning using photolithography and dry etching.

  Instead of photolithography or dry etching, the catalytic metal layer 6 may be patterned by a lift-off method.

  Subsequently, as shown in FIG. 8B, a plurality of carbon nanotubes 7 are grown by the hot filament CVD (Chemical Vapor Deposition) method using the catalytic action of the catalytic metal layer 6, and these carbon nanotubes 7 are wicked. 3.

  The growth conditions of the carbon nanotube 7 are not particularly limited. In this example, a mixed gas of ethylene gas and argon gas is used as the source gas, and the total gas pressure of the source gas in a growth chamber (not shown) is set to 1 kPa. The partial pressure ratio between ethylene gas and argon gas is, for example, about 1: 9. Moreover, the temperature of a hot filament shall be about 700 degreeC, for example.

  The catalytic metal layer 6 is condensed into granular metal particles when the raw material gas is introduced into the growth chamber, and the carbon nanotubes 7 grow to a length of about 150 μm to 200 μm only on the metal particles.

  Since the carbon nanotubes 7 have a property of growing perpendicular to the inner surface 2x, the extending direction of the carbon nanotubes 7 is parallel to the normal direction n of the inner surface 2x.

  Further, the raw material gas is not limited to ethylene gas, and there is a hydrocarbon gas such as methane gas or an alcohol gas such as ethanol or methanol. Further, instead of the hot filament CVD method, a thermal CVD method or a remote plasma CVD method may be used.

  FIG. 12B is an enlarged plan view of the inner surface 2x after the completion of this process.

  As shown in FIG. 12B, each carbon nanotube 7 is formed only in the stripe region R provided with the catalytic metal layer 6 (see FIG. 12A), and is formed on the inner surface 2x outside the stripe region R. The carbon nanotubes 7 do not grow.

  Next, as shown in FIG. 9A, an alumina film is formed as a coating 8 on each of the inner surface 2x and the surface of the carbon nanotube 7 by an ALD (Atomic Layer Deposition) method.

In the ALD method, a mixed gas of trimethylaluminum (Al (CH ₃ ) ₃ ) and water (H ₂ O) is used as a source gas, and the film forming temperature is set to 200 ° C.

  Although the film thickness of the film 8 is not particularly limited, it is preferable to form the film 8 to a thickness of about 1 nm to 20 nm from the viewpoint of enhancing the elasticity of the carbon nanotubes by the film 8 as described above.

Furthermore, the material of the film 8 is not limited to alumina, and a hydrophilic metal oxide can be adopted as the material of the film 8. Examples of such metal oxides include titanium oxide (TiO _x ), hafnium oxide (HfO _x ), iron oxide (FeO _x ), indium oxide (InO _x ), and lanthanum oxide (LaO _x ).

Also, molybdenum oxide (MoO _x ), niobium oxide (NbO _x ), nickel oxide (NiO _x ), ruthenium oxide (RuO _x ), silicon oxide (SiO ₂ ), vanadium oxide (VO _x ), tungsten oxide (WO _x ) Alternatively, yttrium oxide (YO _x ), zirconium oxide (ZrO _x ), or the like may be used as the material of the coating 8.

  Next, as shown in FIG. 9B, the coating 8 is dry-etched with argon plasma to remove the coating 8 from the tip 7a of the carbon nanotube 7 and expose the tip 7a.

  Note that the length z of the tip 7a to be exposed is about several tens of μm, for example, 50 μm.

The dry etching conditions are not particularly limited. In this embodiment, the pressure of argon gas in an etching chamber (not shown) is 3.3 × 10 ⁻⁴ Torr, the acceleration voltage applied to the argon gas is 400 V, and the acceleration current is 200 mA. The etching time is, for example, about 5 minutes to 10 minutes.

  Next, as shown in FIG. 10, two halves 2y on which the carbon nanotubes 7 are erected are prepared as the wick 3 as described above. And the pipe 2 provided with the cavity S inside is obtained by joining each half body 2y by the diffusion joining method.

  Next, steps required until a sectional structure shown in FIG.

  First, after a working fluid such as water is infiltrated into the wick 3 in the pipe 2, the inside of the pipe 2 is depressurized by a vacuum pump (not shown).

  And the inside of the pipe 2 is sealed by joining the copper caps 2z to both ends of the pipe 2 by a diffusion bonding method or the like.

  As described above, the basic structure of the heat transport device 1 according to this embodiment is completed.

(Second Embodiment)
In this embodiment, the heat transport efficiency of the heat transport device is further increased as follows.

  FIG. 13 is a cross-sectional view of the heat transport device according to the present embodiment.

  In FIG. 13, the same elements as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted below. The same applies to FIG. 14 described later.

  The heat transport device 20 according to the present embodiment is a heat pipe, and has a plurality of carbon nanotubes 7 as wicks 3 on the inner surface 2x of the pipe 2 as in the first embodiment.

  And the hydrophilic film 8 demonstrated in 1st Embodiment is formed in the part except the front-end | tip part 7b among the surfaces of the carbon nanotube 7. FIG.

  FIG. 14 is an enlarged cross-sectional view of the inner surface 2x.

  As shown in FIG. 14, a plurality of stripe regions R are provided on the inner surface 2x. The stripe region R is a region where a plurality of carbon nanotubes 7 are erected as the wick 3, and is provided so as to extend from the evaporation unit 2a toward the condensation unit 2b.

  On the other hand, the region between the adjacent stripe regions R becomes the channel D through which the liquid-phase working fluid C1 flows as described in the first embodiment. In the channel D, the working fluid C1 is pushed out from the condensing part 2b to the evaporation part 2a by the capillary force acting from the carbon nanotubes 7 in the adjacent stripe region R. The capillary force depends on the interval W2 between the adjacent stripe regions R, and the capillary force increases as the interval W2 becomes narrower.

  In the present embodiment, the capillary force acting on the working fluid C1 in the vicinity of the evaporator 2a is strengthened by narrowing the interval W2 from the condenser 2b toward the evaporator 2a. Accordingly, the amount of the liquid-phase working fluid C1 supplied from the channel D to the evaporation unit 2a is increased, and the heat transport efficiency of the heat transport device 20 can be further increased.

  Further, since the interval W2 is wide in the vicinity of the condensing unit 2b, the resistance that the liquid-phase working fluid C1 receives from the channel D is reduced. Thereby, the flow of the working fluid C1 in the vicinity of the condensing part 2b becomes smooth, and further improvement in heat transport efficiency can be realized.

(Third embodiment)
In the present embodiment, by using a method different from that of the second embodiment, the heat transport efficiency of the heat transport device is further increased as follows.

  FIG. 15 is a schematic cross-sectional view in the longitudinal direction of the heat transport device according to the present embodiment. In FIG. 15, the same elements as those described in the first embodiment and the second embodiment are denoted by the same reference numerals as those in these embodiments, and the description thereof is omitted below.

  The heat transport device 30 according to the present embodiment is a heat pipe as in the first and second embodiments, and has a plurality of carbon nanotubes 7 as wicks 3 on the inner surface 2x of the pipe 2.

  As in the first embodiment, an alumina film is formed on the carbon nanotube 7 as a hydrophilic film 8, and the tip 7 a of the carbon nanotube 7 is not covered with the film 8 but exposed.

  In the present embodiment, the length L of the carbon nanotube 7 is shortened from the evaporation unit 2a toward the condensing unit 2b. In FIG. 15, the width of the pipe 2 is exaggerated to make it easy to see the change in the length L along the longitudinal direction of the pipe 2.

  FIG. 16 is a schematic cross-sectional view for explaining the operation of the heat transport device 30.

  As described above, when the length L of the carbon nanotubes 7 is shortened along the longitudinal direction of the pipe 2, the ratio of the length L to the inner diameter A of the pipe 2 decreases from the evaporation section 2a toward the condensation section 2b.

  As a result, the flow path of the gas-phase working fluid C2 expands from the evaporation section 2a toward the condensing section 2b, so that the resistance that the gas-phase working fluid C2 receives from the carbon nanotubes 7 decreases. As a result, the flow of the gas-phase working fluid C2 in the pipe 2 becomes smooth, and the heat transport efficiency of the heat transport device 30 can be improved.

  FIG. 17 is a cross-sectional view schematically showing a method of growing the carbon nanotube 7 in which the length L changes in this order. In FIG. 17, the same elements as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted below.

  In this example, the raw material gas G flows along the inner surface 2x of the pipe 2 and the direction in which the raw material gas G flows is a direction from the evaporation unit 2a to the condensing unit 2b. Note that the type of source gas G and other growth conditions are the same as those in the first embodiment, and are therefore omitted.

  In this way, the carbon nanotubes 7 grow longer due to the large amount of the source gas G in the vicinity of the evaporation section 2a on the upstream side of the source gas G. On the other hand, in the vicinity of the condensing part 2b on the downstream side of the raw material gas G, a certain amount of the raw material gas G is consumed upstream, so that the carbon nanotubes 7 grow only to a short length.

  As a result, as described above, the carbon nanotubes 7 that become shorter from the evaporation unit 2a toward the condensation unit 2b can be formed. According to this growth method, the difference in length of the carbon nanotubes 7 in each of the evaporation section 2a and the condensation section 2b is about 100 μm.

(Fourth embodiment)
In the present embodiment, an electronic apparatus including the heat transport device 1 described in the first embodiment will be described.

  FIG. 18 is a schematic plan view of the electronic device 35 according to the present embodiment.

  The electronic device 35 is a mobile electronic device such as a smartphone or a tablet terminal, and includes a substantially rectangular casing 36 that houses the heat transport device 1 and the heat generating component 11. Instead of the heat transport device 1, the heat transport devices 20 and 30 described in the second and third embodiments may be used.

  The heat generating component 11 is, for example, a CPU, and is thermally connected to the evaporation unit 2 a of the heat transport device 1. Thereby, the heat generated in the heat generating component 11 is transported to the condensing part 2b through the heat transport device 1, and the heat generating component 11 can be cooled.

  Further, as described in the first embodiment, the heat transport efficiency of the heat transport device 1 is enhanced by forming the hydrophilic coating 8 on the carbon nanotubes 7 (see FIG. 3). The reliability of the electronic device 35 can be improved by cooling quickly.

(Fifth embodiment)
In the first to fourth embodiments, a heat pipe is cited as an example of a heat transport device. On the other hand, this embodiment demonstrates the vapor chamber which is another example of a heat transport device.

  The vapor chamber is a flat heat pipe. Hereinafter, the vapor chamber is used as an interposer of a semiconductor device.

  FIG. 19 is a cross-sectional view of the semiconductor device according to the present embodiment.

  The semiconductor device 40 includes a circuit board 41, first to third semiconductor elements 42 to 44, first and second vapor chambers 45 and 46, and a heat dissipation member 50.

  Among these, each of the first to third semiconductor elements 42 to 44 is an example of a heat generating component, and is manufactured by forming a circuit on a silicon substrate by a semiconductor process. As shown in the dotted circle, the first and second semiconductor elements 42 and 43 are provided with a first conductor plug 51 as a TSV (Through Silicon Via) penetrating these elements. The material of the first conductor plug 51 is not particularly limited. In this example, copper having excellent conductivity is used as the material of the first conductor plug 51.

  On the other hand, each of the first and second vapor chambers 45 and 46 is produced by processing a silicon substrate in the same manner as the first to third semiconductor elements 42 to 44, and a liquid such as water is contained therein. A cavity S that contains the phase working fluid C1 and is in a reduced pressure state is defined.

  The first and second vapor chambers 45 and 46 have a flat plate shape and function as an interposer that electrically connects the first to third semiconductor elements 42 to 44.

  In the present embodiment, by holding the liquid-phase working fluid C1 in the cavities S of the vapor chambers 45 and 46, the vapor chambers 45 and 46 have a cooling function using the heat of vaporization of the working fluid C1. .

  Each of the first and second vapor chambers 45 and 46 is provided with a copper plug as a second conductor plug 52 penetrating these substrates.

  The connection form of the circuit board 41, the first to third semiconductor elements 42 to 44, and the first and second vapor chambers 45 and 46 is not particularly limited.

  In this embodiment, a solder bump is provided as a terminal 55 between the circuit board 41 and the first semiconductor element 42, and the circuit board 41 and the first semiconductor element 42 are electrically and mechanically connected via the terminal 55. Connect to.

  An underfill resin 49 for increasing the connection strength is filled between the circuit board 41 and the first semiconductor element 42. The underfill resin 49 is also filled between the first semiconductor element 42 and the first vapor chamber 45 and between the second semiconductor element 43 and the first vapor chamber 45.

  Further, the underfill resin 49 is also filled between the second semiconductor element 43 and the second second vapor chamber 46 and between the third semiconductor element 44 and the second vapor chamber 46.

  Further, a terminal 55 for connecting these is also provided between the first semiconductor element 42 and the first vapor chamber 45.

  The terminal 55 is joined to the first conductor plug 51 of the first semiconductor element 42 and the second conductor plug 52 of the first vapor chamber 45, whereby the first semiconductor element 42 and the first vapor are connected. The chamber 45 is electrically and mechanically connected. The same applies to the connection between the second semiconductor element 43 and the second vapor chamber 46.

  The terminal 55 may be omitted, and the first conductor plug 51 and the second conductor plug 52 may be directly connected.

  Then, the terminal 55 is joined to the second conductor plug 52 of the first vapor chamber 45, whereby the first vapor chamber 45 and the second semiconductor element 43 are connected to each other. The same applies to the connection between the second vapor chamber 46 and the third semiconductor element 44.

  The planar sizes of the first to third semiconductor elements 42 to 44 and the first and second vapor chambers 45 and 46 are not particularly limited.

  In the present embodiment, the upper surface 45 a of the first vapor chamber 45 protrudes from the second semiconductor element 42 by making the planar size of the second semiconductor element 43 smaller than that of the first vapor chamber 45. To do.

  Similarly, the planar size of the third semiconductor element 44 is made smaller than that of the second vapor chamber 46 so that the upper surface 46 a of the second vapor chamber 46 protrudes from the third semiconductor element 44.

  On the other hand, the heat radiating member 50 has a function of radiating heat generated inside the first to third semiconductor elements 42 to 44 to the outside, and a metal having good heat conductivity such as copper is used as the material thereof. . The heat radiating member 50 also serves as a lid that covers the first and second vapor chambers 45 and 46 and the first to third semiconductor elements 42 to 44.

  Further, first to third lower surfaces 50 a to 50 c having different heights are provided on the inner surface of the heat radiating member 50.

  The first lower surface 50a is thermally connected to the upper surface 45a of the first vapor chamber 45 protruding from the second semiconductor element 43 as described above via the bonding member 59 made of solder, indium or the like. The

  On the other hand, the second lower surface 50b is positioned higher than the first lower surface 50a, and the upper surface 46a of the second vapor chamber 46 protruding from the third semiconductor element 44 through the bonding member 59 as described above. Thermally connected.

  The third lower surface 50 c is at a higher position than the second lower surface 50 b and is thermally connected to the upper surface 44 a of the third semiconductor element 44 through the bonding member 59.

  Further, the heat radiating member 50 is provided with a first hole 50x and a second hole 50y. A first opening 45x is formed in the first vapor chamber 45 below the first hole 50x, and the first hole 50x is a cavity of the first vapor chamber 45 through the first opening 45x. Connected to S.

  Similarly, a second opening 46x is formed in the second vapor chamber 46 below the second hole 50y, and the second hole 50y passes through the second opening 46x, and the second hole 50y passes through the second substrate 46. Leading to the cavity S.

  Note that a third opening 59a is provided in the bonding member 59 below the holes 50x and 50y. Since the bonding member 59 around the third opening 59a has good adhesion to the heat dissipation member 50 and the vapor chambers 45 and 46, the reduced-pressure atmosphere in the cavity S passes through the bonding member 59 around the opening 59a. There is no leakage outside.

  And on the said heat radiating member 50, the 1st piping 61 and the 2nd piping 62 connected to each of the 1st hole 50x and the 2nd opening 50y are provided. As a material of the first pipe 61 and the second pipe 62, for example, a metal such as copper can be used. Further, since the end points 61 a and 62 a of these pipes 61 and 62 are closed, the airtightness in the cavity S of the first vapor chamber 45 and the second vapor chamber 46 is maintained.

  Further, the heat radiating member 50 is connected to the peripheral edge of the circuit board 41 through a metal stiffener 65. The stiffener 65 has a function of preventing the circuit board 41 from warping, and is bonded to each of the circuit board 41 and the heat dissipation member 50 by an adhesive 66. The stiffener 65 also has a function as a spacer that matches the contact surface of the heat dissipation member 50 with the heights of the semiconductor elements 42 to 44.

  A plurality of solder bumps are provided on the back surface of the circuit board 41 as the external connection terminals 68 of the semiconductor device 40.

  FIG. 20 is a plan view when the first vapor chamber 45 is cut along the line II in FIG.

  As shown in FIG. 20, a plurality of the above-described second conductor plugs 52 are provided at intervals from each other in plan view.

  Further, the cavity S is larger than the first semiconductor element 42 in plan view. In order to prevent the strength of the first vapor chamber 45 from being reduced by the large cavity S as described above, a plurality of pillars 45y are provided inside the cavity S, and the pillars 45y allow the first vapor chamber 45 to Strength is reinforced.

  FIG. 21 is a plan view of the second vapor chamber 46 taken along line II-II in FIG.

  Unlike the first vapor chamber 45, the second vapor chamber 46 of FIG. 21 does not have a column, but a column may be provided in the cavity S to reinforce the second vapor chamber 46.

  Next, the operation of the first vapor chamber 45 and the second vapor chamber 46 will be described with reference to FIGS. 22 (a) and 22 (b).

  FIG. 22A is a schematic plan view of the first vapor chamber 45. In FIG. 22A, the column 45y and the second conductor plug 52 are omitted in order to prevent the drawing from being complicated.

  Moreover, FIG.22 (b) is sectional drawing which follows the III-III line of Fig.22 (a).

  As shown in FIG. 22B, in this example, a first wick 3a and a second wick 3b are provided on the upper surface and the lower surface of the cavity S, respectively. Of these, the first wick 3a has a function of holding the liquid-phase working fluid C1 by capillary force, and the second wick 3b has a function of promoting the condensation of the gas-phase working fluid C2.

  Further, as in the first to fourth embodiments, each wick 3 a, 3 b is formed from a plurality of carbon nanotubes 7. An alumina film is formed as a hydrophilic coating 8 on the surface of each carbon nanotube 7.

  Here, when the first semiconductor element 42 (see FIG. 19) under the first vapor chamber 45 generates heat, the lower surface of the first vapor chamber 45 is heated.

  Thereby, the liquid-phase working fluid C1 evaporates in the cavity S, but since the peripheral edge of the first vapor chamber 45 is cooled by the heat radiating member 50 (see FIG. 19), the gas-phase working fluid C2 is the first working fluid C2. The vapor chamber 45 is cooled and liquefied at the periphery.

  In addition, when the first wick 3a is heated in this way, the working fluid C1 becomes insufficient due to evaporation of the liquid-phase working fluid C1 in the heated portion. Comes to flow.

  As described above, in the first vapor chamber 45, the working fluid circulates in the cavity S by repeating heating and cooling, and the heat of the first semiconductor element 45 is transferred to the periphery of the first vapor chamber 45 by the working fluid. The first semiconductor element 45 can be cooled by being transported.

  In particular, in this example, since the carbon nanotubes 7 of the first wick 3a are hydrophilized with the coating 8 as in the first to fourth embodiments, the flow of the liquid-phase working fluid C1 in the first wick 3a It becomes smooth and the heat transport efficiency of the first vapor chamber 45 is enhanced.

  Although not shown, the second vapor chamber 46 also has a first wick 3a and a second wick 3b, as in the first vapor chamber 45. Thereby, similarly to the first vapor chamber 45, the heat transport efficiency of the second vapor chamber 46 can be increased.

  As described above, according to the present embodiment, the heat transport efficiency of each of the vapor chambers 45 and 46 is increased by making the first wick 3a hydrophilic. As a result, the semiconductor elements 42 to 44 are efficiently cooled by the vapor chambers 45 and 46, so that it is possible to prevent the semiconductor elements 42 to 44 from being destroyed by heat, and thus the semiconductors. The reliability of the device 40 can be increased.

  In addition, since the material of the first vapor chamber 45 and the second vapor chamber 46 is silicon like the first to third semiconductor elements 42 to 44, the vapor chambers 45 and 46 and the semiconductor elements 42 to 44 are used. The difference in thermal expansion is not likely to occur between Therefore, it is possible to suppress the occurrence of poor connection between the vapor chambers 45 and 46 and the semiconductor elements 42 to 44 due to the difference in thermal expansion amount, and the reliability of the semiconductor device 40 can be further improved.

  Next, a method for manufacturing the semiconductor device according to the present embodiment will be described.

  First, a method for manufacturing the first vapor chamber 45 will be described with reference to FIGS.

  23 to 26 are cross-sectional views of the first vapor chamber 45 according to the present embodiment during manufacture.

  First, as shown in FIG. 23A, a first silicon substrate 71 having a thickness of about 300 μm to 500 μm is prepared, and a first resist film 72 is formed thereon. As the first silicon substrate 71, a wafer-like substrate that is not separated into pieces by dicing can be used.

  Then, the first silicon substrate 71 is dry-etched using the first resist film 72 as a mask, thereby forming a recess 71 a in the first silicon substrate 71.

  Note that the portion of the first silicon substrate 71 that remains without being etched becomes the protrusion 71d and the aforementioned pillar 45y (see FIG. 20).

The etching gas used in this etching is not particularly limited, but in this example, a mixed gas of SF ₆ gas and C ₄ F ₈ gas is used as the etching gas.

  Thereafter, the first resist film 72 is removed.

  Next, as shown in FIG. 23B, a second resist film 73 is formed on the first silicon 71 that is upside down from FIG. Then, the first opening 45x is formed in the first silicon substrate 71 by dry etching the first silicon substrate 71 while using the second resist film 73 as a mask.

  The diameter of the first opening 45x is not particularly limited, but in this example, the diameter is about 1 mm.

Further, in this dry etching, a mixed gas of SF ₆ gas and C ₄ F ₈ gas can be used as an etching gas, as in FIG.

  Thereafter, the second resist film 73 is removed.

  Subsequently, as shown in FIG. 24A, a second silicon substrate 75 is prepared separately from the first silicon substrate 71 described above.

  Then, by performing the steps of FIG. 8A to FIG. 9B of the first embodiment, a plurality of carbon nanotubes 7 are grown as the first wick 3a on the surface of the second silicon substrate 75, and A hydrophilic coating 8 is formed on the surface of the carbon nanotube 7.

  Similar to the first silicon substrate 71, a wafer-like substrate that is not separated into pieces by dicing can be used as the second silicon substrate 75.

  Further, the second wick 3b (see FIG. 22B) may be formed on the first silicon substrate 71 (see FIG. 23B) by the same method.

  Next, steps required until a sectional structure shown in FIG.

  First, after dicing, each of the first silicon substrate 71 and the second silicon substrate 75 is separated into individual pieces, and then the surfaces of the substrates 71 and 75 are activated with nitrogen plasma or the like.

  The first silicon substrate 71 and the second silicon substrate 75 are bonded to each other by heating the silicon substrates 71 and 75 at a temperature of about 300 ° C. for about 2 to 3 hours. Such a bonding method is also called a plasma activated bonding method.

  By joining the first silicon substrate 71 and the second silicon substrate 75 in this manner, a cavity S partially defined by the recess 71a is formed.

  The first silicon substrate 71 and the second silicon substrate 75 bonded together in this way are an example of the main body of the first vapor chamber 45.

  Next, as illustrated in FIG. 25A, a third resist film 77 is formed on the second silicon substrate 75.

  Then, using the third resist film 77 as a mask, the first silicon substrate 71 and the second silicon substrate 75 are etched to form a hole 75a in the protrusion 71d.

An etching gas that can be used in this dry etching is, for example, a mixed gas of SF ₆ gas and C ₄ F ₈ gas.

  Thereafter, the third resist film 77 is removed.

  Next, as shown in FIG. 25B, a silicon oxide film is formed as an insulating film 78 on the second silicon substrate 75 and in the hole 75a by the CVD method, and then the insulating film 78 is etched back. It is left only on the side surface of the hole 75a.

  Thereafter, a copper seed layer (not shown) is formed in the hole 75a by sputtering, and an electrolytic copper plating film is formed as the second conductor plug 52 in the hole 75a using the seed layer as a power feeding layer.

  Subsequently, as shown in FIG. 26A, the back surface 71c of the first silicon substrate 71 is back-ground so that the second conductor plug 52 is exposed on the back surface 71c.

  Next, as shown in FIG. 26B, a metal layer 81 is formed on the second silicon substrate 75 to improve the wettability of the above-described joining member 59 (see FIG. 19).

  The metal layer can be formed, for example, by forming a nickel film and a titanium film in order from the bottom by sputtering, and leaving these laminated films only on the periphery of the second silicon substrate 75 by lift-off method or the like.

  The basic structure of the first vapor chamber 45 is completed through the steps so far.

  Note that the second vapor chamber 46 (see FIG. 19) can also be produced in the same manner as the first vapor chamber 45.

  The subsequent steps will be described with reference to FIGS. 27 to 29 are cross-sectional views of the semiconductor device according to the present embodiment during manufacture.

  First, as shown in FIG. 27, the first semiconductor element 42, the first vapor chamber 45, the second semiconductor element 43, the second vapor chamber 46, and the third semiconductor element 42 are sequentially formed on the circuit board 41 from the bottom. The semiconductor element 44 is stacked.

  A terminal 55 such as a solder bump is previously bonded to the lower surface of each of the first vapor chamber 45 and the second vapor chamber 46, and an underfill resin 49 is provided around the terminal 55.

  Then, by reflowing and melting the terminal 55, the circuit board 41, the semiconductor elements 42 to 44, and the first and second vapor chambers 45 and 46 are fixed to each other via the terminal 55.

  In order to increase the connection strength between the first semiconductor element 42 and the circuit board 41, an underfill resin 49 is provided in advance on the lower surface of the first semiconductor element 42. The same applies to the second semiconductor element 43 and the third semiconductor element 44.

  Next, as shown in FIG. 28, on the circuit board 41 on which the first to third semiconductor elements 42 to 44 are stacked as described above, the above-described first and second metal pipes 61, The heat radiating member 50 provided with 62 is arranged.

  The heat radiating member 50 has the first to third lower surfaces 50a to 50c having different heights as described above, and the metal layer 81 is provided in advance on the lower surfaces 50a to 50c before this step. . The metal layer 81 is also provided in advance on the third semiconductor element 44.

  In this step, the joining member 59 is disposed on the metal layer 81 of the first vapor chamber 45, and the joining member 59 is heated and melted, whereby the first vapor chamber 45 and the first vapor chamber 45 are joined to each other. The heat radiating member 50 is connected. As a material of the joining member 59, solder or indium can be adopted as described above.

  Similarly, the second vapor chamber 46 and the heat dissipation member 50 are also connected, and the third semiconductor element 44 and the heat dissipation member 50 are also connected.

  The circuit board 41 and the heat dissipation member 50 are connected to each other via the adhesive 66 and the stiffener 65 as described above.

  Next, the process shown in FIG. 29 will be described.

  First, the liquid-phase working fluid C1 is supplied to the cavities S of the first vapor chamber 45 and the second vapor chamber 46 using the first pipe 61 and the second pipe 62, respectively. And after decompressing the inside of these cavities S, each end 61a, 62a of each of the 1st piping 61 and the 2nd piping 62 is welded, and each of the 1st piping 61 and the 2nd piping 62 is made. Block it.

  Thereafter, a plurality of solder bumps are joined to the circuit board 41 as the external connection terminals 68.

  Thus, the semiconductor device 40 according to this embodiment is completed.

  The following additional notes are disclosed for each embodiment described above.

(Appendix 1) A body with a cavity;
A plurality of carbon element linear structures standing on the cavity-side surface of the main body;
A hydrophilic film formed on the surface of the linear structure;
A working fluid held between each of the plurality of linear structures;
A heat transport device comprising:

  (Additional remark 2) The said transport film is removed from the front-end | tip part of the said linear structure, The said front-end | tip part is exposed, The heat transport device of Additional remark 1 characterized by the above-mentioned.

  (Appendix 3) The heat transport device according to appendix 1 or appendix 2, wherein the coating is formed from the surface of the main body to the root of the linear structure.

(Appendix 4) The main body is a pipe having one end thermally connected to the heat-generating component and the other end having a temperature lower than the one end.
A plurality of stripe regions extending from the one end to the other end are provided on the surface of the main body at intervals,
The heat transport device according to any one of appendix 1 to appendix 3, wherein the linear structure is erected in the stripe region.

  (Supplementary note 5) The heat transport device according to supplementary note 4, wherein an interval between adjacent stripe regions becomes narrower from the other end toward the one end.

  (Additional remark 6) The heat transport device of Additional remark 4 characterized by the length of the said linear structure becoming short as it goes to the said other end from the said one end.

  (Additional remark 7) The said main body is a board | substrate provided with the upper surface to which a heat-emitting component is connected, The heat transport device of Additional remark 1 characterized by the above-mentioned.

(Supplementary Note 8) A step of growing a plurality of carbon fiber linear structures on the cavity-side surface of the surface of the main body provided with a cavity;
Forming a hydrophilic film on the surface of the linear structure;
Supplying a working fluid into the cavity;
The manufacturing method of the heat transport device characterized by having.

  (Additional remark 9) The manufacturing method of the heat transport device of Additional remark 8 characterized by further having the process of removing the said film from the front-end | tip part of the said linear structure.

(Appendix 10) a heat transport device;
A heat generating component thermally connected to the heat transport device;
The heat transport device is
A body with a cavity;
A plurality of carbon element linear structures standing on the cavity-side surface of the main body;
A hydrophilic film formed on the surface of the linear structure;
An electronic apparatus comprising: a working fluid held between each of the plurality of linear structures.

DESCRIPTION OF SYMBOLS 1, 20, 30 ... Heat transport device, 2 ... Pipe, 2a ... Evaporation part, 2b ... Condensing part, 2x ... Inner surface, 2y ... Half body, 2z ... Cap, 3 ... Wick, 3a ... First wick, 3b 2nd wick, 6 ... catalytic metal layer, 7 ... carbon nanotube, 7a ... tip, 7b ... root, 8 ... coating, 10 ... heat conduction sheet, 11 ... heat generating component, 35 ... electronic device, 36 ... casing , 40 ... Semiconductor device, 41 ... Circuit board, 42-44 ... First to third semiconductor elements, 45, 46 ... First and second vapor chambers, 45x ... First opening, 45y ... Pillar, 49 ... Underfill resin, 50 ... Heat dissipation member, 51, 52 ... First and second conductor plugs, 55 ... Terminal, 59 ... Joint member, 61,62 ... First and second pipes, 61a, 62a ... Termination, 65 ... Stiffener, 66 ... Adhesive, 68 ... External contact 71, first silicon substrate, 71a, recess, 71c, back surface, 71d, projection, 72, first resist film, 73, second resist film, 75, second silicon substrate, 75a, hole, 77: third resist film, 78: insulating film, 81: metal layer, R: stripe region, D: channel.

Claims (7)

A body with a cavity;
A plurality of carbon element linear structures standing on the cavity-side surface of the main body;
A hydrophilic film formed on the surface of the linear structure;
A working fluid held between each of the plurality of linear structures;
A heat transport device comprising:   The heat transport device according to claim 1, wherein the coating is removed from a tip portion of the linear structure and the tip portion is exposed. The main body is a pipe having one end thermally connected to the heat generating component and the other end having a temperature lower than the one end.
A plurality of stripe regions extending from the one end to the other end are provided on the surface of the main body at intervals,
The heat transport device according to claim 1, wherein the linear structure is erected in the stripe region.   The heat transport device according to claim 3, wherein an interval between the adjacent stripe regions becomes narrower from the other end toward the one end.   The heat transport device according to claim 3, wherein a length of the linear structure is shortened from the one end toward the other end. Growing a plurality of carbon fiber linear structures on the cavity-side surface of the surface of the body provided with a cavity;
Forming a hydrophilic film on the surface of the linear structure;
Supplying a working fluid into the cavity;
The manufacturing method of the heat transport device characterized by having. A heat transport device;
A heat generating component thermally connected to the heat transport device;
The heat transport device is
A body with a cavity;
A plurality of carbon element linear structures standing on the cavity-side surface of the main body;
A hydrophilic film formed on the surface of the linear structure;
An electronic apparatus comprising: a working fluid held between each of the plurality of linear structures.

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