JP5707884B2 - Micro pump and semiconductor device using the same - Google Patents

Description

  The present invention relates to a micropump and a semiconductor device using the micropump.

  The micropump conveys and sends the fluid in the flow path by utilizing the volume change of the flow path that occurs following the deformation of the diaphragm. In a mechanically driven micropump, a piezoelectric material is generally used for the diaphragm. In addition to being applied to microchannels and inkjet heads, micropumps are also being considered for application to water cooling systems for heating elements such as CPUs.

  In response to the recent increase in heat generation due to the miniaturization and high integration of LSIs, development has been advanced to reduce the heat generation in the direction of reducing the power supply voltage. However, in a circuit operating at a low voltage, it is necessary to set the threshold voltage of the transistor low, increasing the leakage current, and the reduction in the amount of heat generated by the low voltage has reached its limit. Against this background, a low-cost cooling system that can cool LSIs, which are extremely high-density heat sources lined up in a reactor of 100 W per cm 2, with high efficiency is desired. Further, not only a semiconductor element that performs signal processing, such as a CPU, but also a semiconductor laser and a light emitting diode for illumination are similarly desired to have a low cost cooling system.

  A water cooling system is one of high-efficiency cooling means that can replace conventional air cooling fans. In the water cooling system, cooling is performed by flowing a coolant (cooling water) through a sealed heat sink called a water jacket. A pump is used for circulating the refrigerant. However, the use of the pump is delayed in introduction because it adds an unprecedented burden in terms of cost and power consumption. Further, when the water jacket is made by miniaturizing the water pillow, the pressure loss of the water channel increases, leading to an increase in mechanical work performed by the pump, resulting in an increase in power consumption. Increasing the size of the pump causes an increase in cost, and an increase in power consumption results in an increase in exhaust heat.

  For these reasons, an effective means is the use of an auxiliary pump. However, conventionally used piezoelectric diaphragm pumps require power to be supplied to the pump to perform mechanical work. However, the piezoelectric actuator has a high operating voltage and involves electrical energy in the drive circuit. Further, since the displacement amount of the piezoelectric body is small, it is difficult to increase the flow rate of the pump.

  A configuration using a bimetal laminate for a flexible diaphragm of an ink ejection device is known (for example, see Patent Document 1). Also known is a microvalve that opens and closes the valve using a bimetal in the flexible part of the valve (see, for example, Patent Document 2). However, in Patent Document 1, since the bimetal laminate is curved by the action of a magnetic field, a current must be applied by providing a plurality of electrodes in series on the bimetal laminate. Moreover, in patent document 2, since the bimetal is thermally deformed by heating with a heater, supply of electrical energy is necessary.

JP 52-055534 A Japanese Patent Laid-Open No. 2000-2622232

  In view of the above problems, it is an object to provide a micropump that operates autonomously without supplying external electric energy and a semiconductor device using the micropump.

In order to achieve the above object, in the first aspect, the micropump comprises:
A high temperature side member located on the heat source side;
A low temperature side member located on the heat dissipation side;
An intermediate layer located between the high temperature side member and the low temperature side member;
A chamber forming a part of a flow path between the intermediate layer and the low temperature side member;
With
The intermediate layer includes a diaphragm, and displacement means for displacing the diaphragm by heat absorption from the high temperature side member and heat radiation from the low temperature side member,
The diaphragm displaces between a first position before displacement and a second position in contact with the low temperature side member due to the displacement, thereby allowing fluid to be taken into and out of the chamber.

In a second aspect, a semiconductor device using a micropump is provided. Semiconductor devices
A micropump having the above-described configuration;
A semiconductor element in contact with the high temperature side member of the micropump;
A circulation system connected to the micropump for circulating the fluid.

  With the above configuration, the micropump can be operated autonomously without supplying external electric energy. When a micropump is incorporated in a semiconductor device incorporating a cooling system, high cooling efficiency can be achieved.

It is a schematic block diagram for demonstrating the principle of the micropump of Example 1. FIG. It is a figure which shows the operation | movement sequence of the micropump of FIG. It is a figure which shows the formation process of the intermediate | middle layer using a 1st board | substrate. It is a figure which shows the formation process of the intermediate | middle layer using a 1st board | substrate. It is a figure which shows the formation process of the intermediate | middle layer using a 1st board | substrate. It is a figure which shows the formation process of the intermediate | middle layer using a 1st board | substrate. It is a figure which shows the formation process of the intermediate | middle layer using a 1st board | substrate. It is a figure which shows the formation process of the intermediate | middle layer using a 1st board | substrate. It is a figure which shows the formation process of the intermediate | middle layer using a 1st board | substrate. It is a figure which shows the formation process of the high temperature side member using a 2nd board | substrate. It is a figure which shows the formation process of the high temperature side member using a 2nd board | substrate. It is a figure which shows the formation process of the high temperature side member using a 2nd board | substrate. It is a figure which shows the formation process of the high temperature side member using a 2nd board | substrate. It is a figure which shows the formation process of the high temperature side member using a 2nd board | substrate. It is a figure which shows the process of the lamination process of a 1st board | substrate and a 2nd board | substrate. It is a figure which shows the formation process of the low temperature side member using a 3rd board | substrate. It is a figure which shows the process of the lamination process to the 1st board | substrate of a 3rd board | substrate. It is a figure which shows the result of the deformation | transformation simulation of the diaphragm by the bimetal used in the Example. It is a displacement distribution map based on the data of FIG. 8A. It is a figure which shows the modification 1 of the micro pump by a bimetal. It is a figure which shows the modification 2 of the micro pump by a bimetal. It is a figure which shows the modification 3 of the micro pump by a bimetal. It is a schematic block diagram of the semiconductor device using the micro pump by a bimetal. FIG. 3 is a schematic configuration diagram of a micropump of Example 2. It is a figure which shows the operation | movement sequence of the micropump of FIG. FIG. 6 is a process diagram of forming an intermediate layer of the micropump of Example 2. FIG. 6 is a process diagram of forming an intermediate layer of the micropump of Example 2. FIG. 6 is a process diagram of forming an intermediate layer of the micropump of Example 2. FIG. 6 is a process diagram of forming an intermediate layer of the micropump of Example 2. FIG. 6 is a process diagram of forming an intermediate layer of the micropump of Example 2. FIG. 6 is a process diagram of forming an intermediate layer of the micropump of Example 2. It is a lamination process figure of the 1st substrate of the micro pump of Example 2, and the 2nd substrate. It is a lamination process figure of the 1st substrate of the micro pump of Example 2, and the 3rd substrate. It is a lamination process figure of the 1st substrate of the micro pump of Example 2, and the 3rd substrate.

  Hereinafter, the configuration, operation, and manufacturing method of a micropump according to an embodiment will be described with reference to the drawings. Through the embodiments, the micropump has a diaphragm that can be deformed and displaced in the flow path in an intermediate layer located at the interface between the high temperature side member provided on the heat source side and the low temperature side member provided on the heat dissipation side. The deformation / displacement of the diaphragm is performed independently by using a bimetal and by the heat absorption action from the high temperature side member and the heat radiation action from the low temperature side member. Bimetal is a combination of two or more types of thin metal plates having different thermal expansion coefficients, and is bent according to a temperature change. By deforming and displacing the diaphragm using bimetal, the pressure in the flow path is changed, and inflow and outflow of fluid to the micropump are realized.

  FIG. 1 is a diagram for explaining the basic principle of the bimetal micropump 10 according to the first embodiment. In the first embodiment, the diaphragm 33 itself is made of bimetal as the diaphragm displacing means. That is, the bimetal constituting the diaphragm serves as the diaphragm displacement means.

  In Example 1, as shown in FIGS. 1 (A) and 1 (B), the micropump 10 includes a high temperature side member 20 located on the heat source side (not shown), a low temperature side member 40 located on the heat dissipation side, It has the intermediate | middle layer 30 located between the high temperature side member 20 and 40 of the low temperature side member. The intermediate layer 30 includes a bimetallic diaphragm 33, an inlet-side inlet valve 35, and an outlet-side outlet valve 37. Between the intermediate layer 30 and the low temperature side member 40 are a chamber 45 and a valve chamber 42 which constitute a flow path in the micropump 10.

  The high temperature side member 20 is in contact with or includes a heat source. The low temperature side member 40 is in contact with the cooling (heat radiation) part or constitutes the cooling (heat radiation) part. The bimetal diaphragm 33 is displaceable between a first position before displacement and a second position in contact with the low temperature side member 40 due to thermal deformation. In the first embodiment, the first position corresponds to the initial position where the diaphragm 33 contacts the high temperature side member 20. The bimetallic diaphragm 33 absorbs heat from the high temperature side member 20 at the first position, thereby deforming the chamber 45 in a direction projecting toward the low temperature side member 40, and comes into contact with the heat radiating portion 41. Heat is released by coming into contact with the low-temperature heat radiation part 41, and the shape returns to the first position after returning to the shape before deformation. In a 1st position, it deform | transforms and displaces again by contacting the high temperature side member 20 and absorbing heat. When the diaphragm 33 repeats the above-described operation due to thermal deformation, the in-valve 35 and the out-valve 37 are driven to take in the fluid into the chamber 45 and discharge the fluid from the chamber 45.

  The diaphragm 33 is composed of an elastic body and is composed of two or more types of elastic body plates having different linear expansion coefficients. As a specific example, the diaphragm 33 includes a first member 31 having a high linear expansion coefficient (high CTE) in direct contact with the high temperature side member 20 in the first position, and a low line positioned on the surface opposite to the high temperature side member 20. The second member 32 having an expansion coefficient (low CTE) is combined. The first member (high CTE member) 31 is, for example, Al, Cu, Se, or an alloy containing these. The second member (low CTE member) 32 is, for example, Si, Mo, W, Cr, Ni, or an alloy containing these. Either one of the first member and the second member may be a semiconductor.

  Since the peripheral edge portion of the diaphragm 33 is held by the holding member 38, when the diaphragm 33 is deformed by heat reception, the diaphragm 33 is deformed so that the central portion projects toward the low temperature side. In response to the change in the position of the diaphragm 33, the in-valve 35 and the out-valve 37 take in and discharge the fluid during the pump operation and prevent the backflow of the fluid (refrigerant).

  The high temperature side member 20 includes a heat receiving part 21 that receives heat by contacting a heating element (not shown in FIG. 1), and a heat transfer part 22 that transfers the heat received by the heat receiving part 21 to the diaphragm. In the first embodiment, the heat transfer unit 22 functions as a contact adjusting unit that controls contact and non-contact between the bimetallic diaphragm 33 and the high temperature side member 20. The high temperature side member 20 and the intermediate layer 30 are connected via a heat insulating material 52. Similarly, the intermediate layer 30 and the low temperature side member 40 are connected via a heat insulating material 51.

  2A and 2B are diagrams showing an operation sequence of the micropump 10 of FIG. The state depicted by the solid line in FIG. 1B, that is, the state in which the diaphragm 33 is in contact with the high temperature side member 20 at the first position without deformation and the in-valve 35 and the out-valve 37 are closed is the initial position. And

  Assume that an LSI element 70 as a heating element is placed on the heat receiving portion 21 of the high temperature side member 20 as shown in FIG. The LSI element 70 is in contact with the high temperature side member 20 on the surface opposite to the bonding surface to the substrate 90. The heat generated by the operation of the LSI element 70 is absorbed by the bimetallic diaphragm 33 through the heat receiving part 21 and the heat transfer part 22. As a result, the temperature of the intermediate layer 30 rises, and the diaphragm 33 is concavely deformed toward the low temperature side member 40 and is displaced to the second position where it contacts the low temperature side member 40. Due to the deformation of the diaphragm 33, the volume of the flow path in the chamber 45 decreases, and the fluid pressure on the outlet side increases. The out valve 37 is pushed up to open, and the fluid is discharged to the discharge pipe 54. At this time, the in-valve 35 is closed.

  Next, as shown in FIG. 2B, the bimetallic diaphragm 33 is brought into contact with the heat radiating portion 41 of the low temperature side member 40 to release heat, and returns to the first position where it contacts the high temperature side member 20. This increases (recovers) the flow path volume in the chamber and reduces the fluid pressure. The inlet side in-valve 35 opens downward by the fluid pressure in the introduction path 34, and the fluid flows into the chamber 45. At this time, the out valve 37 is in a closed state, and the heat radiating portion 41 of the low temperature side member 40 is cooled by the fluid filling the chamber 45. When the diaphragm 33 that has returned to the initial position comes into contact with the high temperature side member 20 and absorbs heat, the micropump 10 shifts to the state of FIG. 2A again, and thereafter, FIG. 2A and FIG. Repeat the operation.

  3A to 3G are diagrams showing a processing step of the first substrate used for the intermediate layer 30 as part of the manufacturing process of the micropump 10. In the first embodiment, a semiconductor material such as single crystal silicon is used for at least one layer of the bimetal constituting the diaphragm 33. Silicon is not only easy to process using semiconductor processes, but also has a thermal conductivity comparable to that of metals at 163 W · mK, and has a line expansion coefficient of 2.9 ppm / K, making it suitable as a component material for micro pumps. ing. In addition, since it is eutectic with the surface of the metal, strong bonding is possible.

  First, as shown in FIG. 3A, a silicon single crystal wafer (referred to as “silicon substrate” as appropriate) 61 is prepared as a first substrate, a resist 62 is applied, and patterning (exposure / development) is performed using the mask 1. . Next, as shown in FIG. 3B, the silicon substrate 61 is etched to a depth of 100 μm using the resist 62 as a mask, and then the resist is removed and washed. As a result, a frame-like protrusion 68 is formed on the silicon substrate 61.

  Next, as shown in FIG. 3C, a resist 64 is applied, the resist 64 is patterned using the mask 2 having an opening in the diaphragm portion, and a chromium film 65 having a thickness of about 50 nm is sputtered on the entire surface. Next, as shown in FIG. 3D, the chromium film 65 is patterned by a lift-off method.

  Next, as shown in FIG. 3E, a 100 μm thick film resist 66 for plating is applied, and an opening 67 through which the chromium film 65 is exposed is formed using the mask 2. Next, as shown in FIG. 3F, a copper or nickel layer 31 is plated and grown to 100 μm by electrolytic plating. The metal layer 31 becomes a bimetallic high CTE member (first member) 31. Thereafter, the plating resist 66 is removed as shown in FIG. 3G. The frame-like protrusion 68 becomes the holding portion 38 that holds the diaphragm 33 in FIG. Thereby, the first substrate 60 in which the high CTE Cu film 31 is formed in the region surrounded by the holding portion 38 on the silicon substrate 61 is completed.

The formation of the intermediate layer 30 described above is merely an example, and when silicon is used for the low-expansion side layer 32 of the bimetal, the linear expansion coefficient of the high-expansion side layer 31 is several times greater than that of silicon. These materials can be used. There are various options for the high expansion layer 31 such as metal, but manganese, chromium, nickel, copper, and alloys thereof are generally used. In the case of using a semiconductor process, copper or nickel that is easy to etch or plate is preferable as described above. Copper has a thermal conductivity of 300 W / mK and a linear expansion coefficient of 145 ppm / K, and a good bimetal can be produced by combining with single crystal silicon. The types of bimetals currently on the market are classified and described in the current JISC2530 “Bimetal plates for electricity”. According to this classification, a material having a curvature coefficient of around 20 × 10 ⁻⁶ / K can be easily obtained as a material classified into the symbol TM1.

  4A to 4E are diagrams showing a process of processing the second substrate used for the high temperature side member 20 as a part of the manufacturing process of the micropump 10. First, as shown in FIG. 4A, a second silicon single crystal wafer (referred to as a “silicon substrate” as appropriate) 25 is prepared as a second substrate. A resist 26 is applied to the entire surface, and the resist 26 is patterned using the mask 3 to form an opening 27 at a predetermined location. Next, as shown in FIG. 4B, inlet / outlet holes 28 are formed in the silicon substrate 25 by the DRIE method using the resist 26 as a mask. Thereafter, the resist 26 is removed.

  Next, as shown in FIG. 4C, a resist 29 is applied to the back surface of the silicon substrate 25, that is, the surface opposite to the side where the inlet / outlet holes 28 are formed, and the resist 29 is patterned using the mask 4, A recess 23 is formed by etching the silicon substrate 25 by the DRIE method. The planar shape of the recess 23 corresponds to the diaphragm 33, the in-valve 35, and the out-valve 37 of the intermediate layer 30. Thereafter, the resist 29 is removed.

  Next, as shown in FIG. 4D, a resist 71 is applied to the back side of the silicon substrate 25, and the resist 71 is patterned using the mask 5. Then, as shown in FIG. 4E, the silicon substrate 25 is etched by the DRIE method using the resist 71 as a mask until it communicates with the inlet / outlet hole 28, and the heat receiving portion 21 and the heat transfer portion ( Contact adjusting means) 22, a fluid introduction path 34, a discharge path 36, and a housing 24 are formed. Thereby, the second substrate 50 on the high temperature side is completed.

  FIG. 5 is a view showing a process of laminating the first substrate 60 constituting the intermediate layer 30 and the second substrate 50 on the high temperature side. As shown in FIG. 5A, the epoxy adhesive 52 is dispensed on the back surface (heat transfer section 22 side) of the second substrate 50, and the first substrate 60 is bonded to the lower surface thereof. In this case, the epoxy adhesive 52 dispensed so as to surround the heat transfer portion (contact adjusting means) 22 in the heat receiving portion 21 of the second substrate 50 is joined to the frame-shaped protrusion of the first substrate 60, that is, the holding portion 38. Is done.

  Next, as shown in FIG. 5B, the silicon substrate 61 has a desired thickness on the back surface of the bonded first substrate 60, that is, the surface opposite to the surface on which the Cu layer 31 as the high CTE layer is formed. Grind and polish until In this example, the silicon substrate 61 is ground and polished until the thickness becomes 100 μm. Thereafter, a resist (not shown) is applied to the polished back surface, and the diaphragm 33, the in-valve 35 and the out-valve 37 are formed using the mask 6. The resist is removed, and the high temperature side member 20 and the intermediate layer 30 of the micropump 10 are completed. The silicon substrate inside the holding portion 38 becomes the low CTE layer (second member) 32 of the diaphragm 33. Further, the silicon substrate corresponding to the fluid introduction path 34 becomes the in-valve 35, and the silicon substrate corresponding to the fluid discharge path 36 becomes the out-valve 37. At this stage, a polymer protective film may be formed on the back surface (polished surface) of the diaphragm 33, the in-valve 35, and the out-valve 37. The epoxy adhesive material 52 that joins the high temperature side member 20 and the intermediate layer 30 functions as a heat insulating material. The in-valve 35 is locked by the housing 24 so as not to open to the introduction path 34 when the micropump 10 is operated. On the other hand, the out valve 37 is configured to open to the discharge path 36 side.

  FIG. 6 is a diagram illustrating a process of processing the third substrate used for the low temperature side member 40 as a part of the manufacturing process of the micropump 10. As shown in FIG. 6A, a third silicon single crystal wafer 41 is prepared as a third substrate. A permanent resist 51 is applied to the entire surface, and the permanent resist 51 is patterned using the mask 7 to form a space 55 having a predetermined shape. The space 55 corresponds to the chamber 45 and the valve chamber 42 of the micropump 10 after assembly. The permanent resist 51 that partitions the space 55 functions as the housing 51 of the micropump 10 and also functions as a heat insulating material between the intermediate layer 40 and the low temperature side member 40. The permanent resist 51 is, for example, an epoxy resin or polyimide. Next, as shown in FIG. 6B, an epoxy adhesive 56 is dispensed at a predetermined location on the patterned permanent resist 51.

  FIG. 7 is a diagram illustrating a process of bonding the third substrate 41 to the stacked body of the first substrate 60 and the second substrate 50 formed in FIG. As shown in FIG. 7A, the back surface of the first substrate 60 is bonded onto the epoxy adhesive 56 of the third substrate 41. At this time, the epoxy adhesive 56 must be applied so as not to interfere with the outlet valve 37 on the outlet side. Next, as shown in FIG. 7B, the joined body is separated into chips by a dicer. When dicing, it is desirable to protect the opening 34 serving as the fluid introduction path 34 and the opening 36 serving as the fluid discharge path 36 to separate the chips. Thus, the main part of the micropump 10 is completed. A chamber 45 that is a part of the flow path is formed between the diaphragm 33 and the low temperature side member 40, and a valve chamber 42 that is a part of the flow path is formed below the in-valve 35 and the out-valve 37. The out valve 37 is locked by a housing 51 so as not to open toward the lower valve chamber 42. FIG. 7C is a schematic top view in this state.

  The inner surface of the micropump 10 may be protected with a polymer protective film (not shown). For example, in order to increase the confidentiality of the micropump 10 and reduce leaks, a polyxylene film is formed by a vapor deposition polymerization method. Finally, an inflow pipe 53 and a discharge pipe 54 (see FIG. 1) (not shown) are connected to the fluid introduction path 33 and the fluid discharge path 36, and the fluid is sealed to complete the micropump.

  FIG. 8A is a deformation simulation data of diaphragm deformation by bimetal, and FIG. 8B is a displacement distribution diagram based on the data of FIG. 8A. In the simulation, a 100 mm thick Cu film is used as the high CTE member (first member) on the upper surface side, and a single crystal silicon film is used as the low CTE member (second member) 100 μm thickness on the lower surface side. It was. Further, as shown in FIG. 1, the diaphragm 33 is formed integrally with the frame (holding portion) 38. When a temperature increase of 50 ° C. is given, it can be seen that the central portion of the diaphragm is deformed into a concave shape as shown in FIGS. 8A and 8B. In this case, however, since the displacement is as small as −4 μm in the Z-axis direction, the space height of the chamber 45 serving as a flow path must be 4 μm when functioning as a micropump. A more effective application example of the bimetal in the micropump will be described in Example 2 described later.

  9 shows a first modification of the micropump of the first embodiment, FIG. 10 shows a second modification of the micropump, and FIG. 11 shows a third modification of the micropump. The same components as those of the micropump 1 in FIG. In the micropump 110A of FIG. 9, the inlet side inflow pipe 53 and the outlet side discharge pipe 54 are provided on the low temperature side. In this configuration, since the heat receiving portion 21 of the high temperature side member 20 faces the flow path, the high temperature side member 20 can be directly cooled. Therefore, the cooling efficiency can be improved. When the micropump 110A is manufactured, an opening is formed in the substrate 41 serving as the low temperature side member 40 using the mask 3 (see FIG. 4A) to form a fluid introduction path and a fluid discharge path. The displacement of the diaphragm 33 due to heat from the high temperature side member 20 and the opening / closing operations of the in-valve 35 and the out-valve 37 are the same as in the first embodiment.

  A micropump 110 </ b> B in FIG. 10 is a further modification of the configuration in FIG. 9, and a cooling water channel 120 is provided in the low temperature side member 40. The cooling water channel 120 functions as a water jacket. The micropump and the water jacket can be integrally formed using a semiconductor process.

  A micropump 110C in FIG. 11 is formed by forming an in-valve 135 and an out-valve 137 with bimetal. In the out valve 137, the stacking of the high CTE material (first member) and the low CTE material (second member) is reversed from the stacking of the diaphragm 33. According to the configuration of FIG. 11, the operation of the in-valve 135 and the out-valve 137 can be made more autonomous rather than depending only on the pressure fluctuation in the chamber 45, so that the diaphragm 33 can be mechanically operated. Dynamic movement (displacement) can be allocated to fluid transport only. Such an effect can be achieved to some extent even if only one of the in-valve 135 and the out-valve 137 is made of bimetal.

  FIG. 12 is a schematic diagram showing a semiconductor device 100 incorporating a micropump as an example of a usage pattern of the micropump. The semiconductor device 100 includes a micropump 110A, an LSI element 70 that contacts the high temperature side member 20 of the micropump 110A, and a circulation system 85 that is connected to the micropump 110A and circulates fluid. The circulation system 85 includes a pipe 81 and a heat exchanger or radiator 82. A main pump 83 may be connected to the circulation system 85. In this case, the micropump 110A functions as an auxiliary pump that operates autonomously. Further, it is desirable to dispose a water jacket 80 in contact with the low temperature side member 40 as a part of the circulation system 85.

  The refrigerant fluid discharged from the main pump 83 enters the water jacket 80, receives the amount of heat transferred from the LSI element 70 through the micro pump 110A, and enters the inlet of the micro pump 110A. When the micro pump 110 </ b> A operates using the temperature difference between the heat source and the water jacket 80, the fluid is discharged from the outlet and circulates through the heat exchanger 82 to the main pump 83. The heat exchanger 82 is a device that moves the amount of heat received from the heat source to the secondary refrigerant, and is a radiator when the secondary refrigerant is air.

  LSI in recent years has an energy density of more than 100 W / cm2 and is approaching the reactor level. What is more troublesome is that the amount of heat generation varies greatly depending on the use situation due to the development of the power saving function. In the absence of the micropump 110A, the main pump 83 must pressurize and circulate the fluid in consideration of all pressure losses between the water jacket 80, the reciprocating piping 81, and the heat exchanger 82. Must be generated. In addition, the pipe 81 from the main pump 83 to the water jacket 80 has a high positive pressure, and the connection portion requires high reliability. Although it is theoretically possible to control the flow rate of the fluid to reduce the power consumption of the main pump 83 or to raise the temperature of the fluid to be discharged to increase the exchange rate in the heat exchanger 82, the water jacket 80 The risk of backflow of heat from the heat source to the heat source is high, and it is difficult to realize because it requires sophisticated pump control.

  On the other hand, in the configuration of FIG. 12, the function of sucking out the fluid from the water jacket 80 can be achieved by the autonomous operation of the diaphragm of the micropump 110A. When the micro pump 110 </ b> A is operating, the main pump 83 only needs to generate a pressure that covers the flow path from the main pump 83 to the water jacket 80 and part of the pressure loss of the water jacket 80. Since the micropump 110A functions as an auxiliary pump in this way, the pressure rising points can be dispersed throughout, so that it is a means for improving the reliability of the fluid circulation system.

  When the micro pump 110A is not operating, it is necessary for the main pump 83 to cover the pressure loss of all the flow paths, and the flow rate is reduced to about 1/2 to 1/3. However, the fact that the micropump 110A is not operating means that the heat generation from the heat source is small, and therefore the necessity for cooling is not high. Therefore, the decrease in cooling capacity is not affected and can be said to be desirable. Moreover, in the micropump 110A, heat moves in one direction from the heat source (LSI element 70) toward the water jacket 80 and does not flow backward. Therefore, it is possible to reduce the power consumption of the pump as compared with the conventional case.

  As described above, by incorporating the micro pump 110A into the semiconductor device 100, when strong cooling is required in the LSI element 70 of the heat source, the cooling efficiency can be automatically increased by the autonomous operation of the micro pump 110A. By causing the micro pump 110A to function as an auxiliary pump, it is possible to reduce the cost by reducing the power of the main pump 83 or reducing the grade. Further, by placing the micropump 110A in the vicinity of the water jacket 80 that causes the largest pressure loss in the cooling circuit, the water pressure in the water pipe can be reduced and the risk of a water leakage accident can be reduced.

  In the example of FIG. 12, only a single LSI element 70 mounted on the main circuit board 90 via the solder bumps 72 is depicted. However, in the semiconductor device 100, a plurality of LSI elements 70 are arranged on the main circuit board 90. It can also be set as the structure to arrange. In this case, the heat exchanger (or the radiator) 82 and the main pump 83 can be shared while the micro pump 110A is disposed in each LSI element 70. Although the micropump 110A is used in the example of FIG. 12, it goes without saying that in the semiconductor device 100, the micropump 10 of FIG. 1 and the micropumps 110B and 110C of the second or third modification can be used in the same form.

  FIG. 13 is a schematic configuration diagram of the bi-pump micro pump 200 according to the second embodiment, and FIG. 14 is a diagram for explaining the operation of the micro pump 200. In the second embodiment, a bimetal displacement means 253 is inserted between the diaphragm 233 and the high temperature side member 20. As shown in FIG. 13, the displacement means 253 is a bimetal including two or more types of elastic members having different linear expansion coefficients, and is a first member 231 of a high CTE material that is in direct contact with the heat transfer portion 22 of the high temperature side member 20. And a second member 232 of low CTE material located on the opposite side to the high temperature side member. The displacement means 253 shall be in contact with the heat transfer part 22 of the high temperature side member 20 at the initial position.

  The micropump 200 includes a high temperature side member 20 located on the heat source side (not shown), a low temperature side member 40 located on the heat dissipation side, and an intermediate layer 230 located between the high temperature side member 20 and the low temperature side member 40. . The intermediate layer 230 includes a diaphragm 233, displacement means 253 for deforming the diaphragm, an inlet-side inlet valve 235, and an outlet-side outlet valve 237. Between the intermediate layer 230 and the low temperature side member 40, a chamber 45 and a valve chamber 42 that constitute a flow path in the micropump 10 are provided. The heat source is a heating element (not shown) such as an electronic component mounted on the heat receiving portion 21 of the high temperature side member 20, for example.

  The diaphragm 233 is displaced between the first position before displacement and the second position that is pressed by the displacement means 253 and contacts the low temperature side member 40 according to the movement of the displacement means 253. That is, as shown in FIG. 14 (A), the displacement means 253 absorbs heat through the heat receiving part 21 and the heat transfer part 22 of the high temperature side member 20 to thereby move away from the heat transfer part 22 (downward in the drawing). Curved). As a result, the diaphragm 233 is pressed toward the low temperature side member 40 and is displaced to the second position in contact with the low temperature side member 40. The volume in the chamber 45 changes due to the displacement of the diaphragm 233, the out valve 237 opens upward as the pressure rises, and the fluid in the chamber 45 is discharged.

  The heat absorbed by the displacement means 253 is released from the heat radiation part 41 of the low temperature side member 40 via the diaphragm 233. Thereby, as shown in FIG. 14B, the bending of the displacement means 253 is eliminated, and the initial position where the high temperature side member 20 comes into contact is restored. As the displacement means 253 returns to the initial position, the pressed diaphragm 233 also returns to the first position. The volume in the chamber is also restored to the original state, and the internal pressure is reduced. The in-valve 235 opens downward and the fluid flows into the chamber 45. The operation of FIG. 14A and FIG. 14B is autonomously repeated due to the presence of a heat source (not shown) mounted on the heat receiving portion 21 of the high temperature side member 20, for example, and the operation of the micropump 200. Will continue.

In the configuration of the second embodiment, the bimetal displacement means 253 is formed in a cantilever structure and functions as an actuator that drives the diaphragm 233 from the first position to the second position. For example, if a bimetal material equivalent to TM1 (classified by KOSC2530) with a thickness of 200 μm, a length of 10 mm, and a width of 10 mm is held in a cantilever shape, the maximum displacement of the free end when the temperature rises by 50 ° C. The amount is 300 to 500 μm. In Example 2, as will be described later, a plurality of displacement means having a triangular shape in plan view are arranged in combination.

  15A to 15F are diagrams illustrating a process of forming the intermediate layer 230 of the micropump 200 according to the second embodiment. First, as shown in FIG. 15A, an SOI substrate 210 is used as a first substrate constituting the intermediate layer 230. The SOI substrate is a substrate in which a silicon oxide film (SiO 2) 212 is inserted between a silicon substrate 211 and a surface silicon (Si) film 213. In the embodiment, the silicon oxide film 212 is used as a sacrificial film. A resist 214 is applied on the SOI substrate 210, and the resist 214 is patterned using the mask 11. Next, as shown in FIG. 15B, the Si film 213 and the SiO2 film 212 are etched using the resist 214 as a mask, and the resist 214 is removed after the etching is completed.

  Next, as illustrated in FIG. 15C, a resist 216 is formed on the entire surface, and the resist 216 is patterned using the mask 12. By patterning, an opening 219 that is a combination of four triangles in a planar shape is formed in the resist 216, and the Si film 213 is exposed in the opening 219. Next, as shown in FIG. 15D, a Cr film 217 having a thickness of 50 nm is sputtered on the entire surface, and the Cr film 217 is patterned by a lift-off method. Thereby, the surface Si film 213 of the SOI substrate 210 becomes a low CTE member (Si film) 232 constituting a layer on one side of the bimetal.

  Next, as shown in FIG. 15E, a plating resist 221 is formed on the entire surface, patterned using the mask 12 used in FIG. 15C, and Cu or Cu is deposited on the Si film 232 by electrolytic plating using the exposed Cr film as a seed. A Ni film 231 is formed. Next, as shown in FIG. 15F, the SiO2 sacrificial film 212 is removed by isotropic etching to form a bimetal displacement means 253 having a cantilever structure. In this example, the cantilever-shaped displacement means 253 is formed by combining four triangles in accordance with the quadrangular diaphragm 233. However, the diaphragm 233 and the chamber 45 may be hexagonal, octagonal, circular, or the like. 6, 8 or more displacement means 253 may be provided. In either case, the diaphragm is pressed at the apex of the triangle and displaced to the low temperature side.

  FIG. 16A is a diagram showing a process of laminating the first substrate 260 on which the displacement means 253 is formed and the second substrate 50 to be the high temperature side member 20. The manufacturing method of the second substrate 50 is the same as that of the first embodiment, and the description is omitted. An epoxy adhesive layer 52 is dispensed on the bonding side surface of the second substrate 50 and bonded onto the first substrate 260.

  FIG. 16B and FIG. 16C are diagrams illustrating a process of laminating a third substrate 41 to be the low temperature side member 40 on the first substrate on which the second substrate is laminated. As shown in FIG. 16B, prior to bonding, the back surface of the silicon substrate 211 on which the second substrate is laminated is changed to a desired thickness suitable for the diaphragm 233, the in-valve 235 and the out-valve 237, for example, 100 μm. Grind and polish. Thereby, the laminated body containing the high temperature side member 20, the intermediate | middle layer 230, and the housing 24 is completed. On the other hand, a low temperature side member 40 is prepared by processing the permanent resist 51 at a predetermined location on the third substrate 41 in the same manner as in the first embodiment. An epoxy adhesive 56 is applied to the permanent resist 51.

  As shown in FIG. 16C, the high temperature side member 20, the intermediate layer 230, and the low temperature side member 40 are obtained by bonding the third substrate to the laminate of the first substrate and the second substrate through an epoxy adhesive. The micropump 200 is completed. The intermediate layer 230 includes a diaphragm 233, an in-valve 235, an out-valve 237, and bimetal displacement means 253, and a chamber 45 is formed between the intermediate layer 230 and the low temperature side member 40. The micropump 200 is completed by connecting piping (not shown) constituting the circulation system to the inlet side opening 34 and the outlet side opening 36 and enclosing the fluid.

  In the structure of the second embodiment, the area of the diaphragm 233 is 20 mm × 20 mm, and the heat capacity of the bimetal constituting the displacement means 253 is about 0.1 uJ / K. If the total thermal resistance including contact thermal resistance is 1K · W, the time constant of temperature change is 0.1us (microseconds) from the product, and heat absorption or heat dissipation can be completed instantaneously. The actual operation is limited by the viscous resistance of the fluid, but if the operation at 100 Hz is performed, a flow rate of 10 ml / s is obtained, and it is expected that a heat quantity of several hundred W can be transported. In an actual usage mode, if the intermediate layer 230 has a certain heat capacity, or a bypass channel (not shown) is formed to cool the high temperature side, further efficient cooling is possible.

  As described above, the micropump of the present invention is powered by thermal deformation of the displacement means having a bimeta structure. The displacement means of the bimetal structure is a displacement means that pressurizes and deforms the diaphragm in the second embodiment. When the bimetal of the intermediate layer comes into contact with the high temperature side, the endothermic deformation is caused to displace the diaphragm to the low temperature side. By radiating heat through contact with the low temperature side, the diaphragm (and the displacement means) returns to its original position. With such a configuration, the micropump can be operated autonomously without supplying external electric energy or applying a voltage. When the micro pump is used as an auxiliary pump for a semiconductor device with a built-in cooling system, it is possible to provide an efficient cooling structure that automatically increases the cooling efficiency when strong cooling is required.

  As described above, the shape of the diaphragm or chamber is not limited to a rectangle, and may be a polygon or a circle. Further, the production of the bimetal serving as the displacement means is not limited to the formation of the metal film on the silicon substrate, and a laminate of two kinds of metals having different linear expansion coefficients may be used. Further, instead of forming the high temperature side member, the intermediate layer, and the low temperature side member of the micropump by a semiconductor process, the micro pump may be manufactured by an arbitrary method such as molding. Further, the micropump 200 of the second embodiment may be used as a micropump incorporated in the semiconductor device shown in FIG.

The following notes are presented for the above explanation.
(Appendix 1)
A high temperature side member located on the heat source side;
A low temperature side member located on the heat dissipation side;
An intermediate layer located between the high temperature side member and the low temperature side member;
A chamber forming a part of a flow path between the intermediate layer and the low temperature side member;
With
The intermediate layer includes a diaphragm and displacement means (31, 32, 253) for displacing the diaphragm by heat absorption from the high temperature side member and heat radiation from the low temperature side member,
The diaphragm is displaced between a first position before displacement and a second position in contact with the low temperature side member due to the displacement, thereby allowing fluid to be taken into and out of the chamber. A micro pump.
(Appendix 2)
The displacement means has a first linear expansion coefficient and a first member located on the high temperature side member side, and a second linear expansion coefficient smaller than the first linear expansion coefficient and the high temperature The micropump according to appendix 1, wherein the micropump is a bimetal including a side member and a second member located on the opposite side.
(Appendix 3)
The micropump according to appendix 2, wherein the diaphragm is in contact with the high temperature side member at the first position.
(Appendix 4)
The micropump according to appendix 2, wherein the displacement means is a bimetal having a cantilever structure disposed between the diaphragm and the high temperature side member.
(Appendix 5)
The micropump according to claim 4, wherein the bimetal having the cantilever structure is bent by heat from the high temperature side member, and the diaphragm is displaced to the second position in contact with the low temperature side member. (Appendix 6)
The intermediate layer further includes a first valve located in a fluid introduction path for introducing the fluid into the chamber, and a second valve located in a fluid discharge path for discharging the fluid from the chamber, the diaphragm, the first The micropump according to any one of appendices 1 to 5, wherein the one valve and the second valve are integrally formed.
(Appendix 7)
The micropump according to any one of appendices 1 to 6, wherein at least one of the first member and the second member of the diaphragm is a semiconductor.
(Appendix 8)
The micropump according to any one of appendices 1 to 6, wherein at least one of the first member and the second member of the diaphragm is a metal.
(Appendix 9)
The micropump according to any one of appendices 1 to 6, wherein the first member of the diaphragm is Al, Cu, Se, Ni, or an alloy containing these.
(Appendix 10)
The micro pump according to any one of appendices 1 to 6, wherein the second member of the diaphragm is Si, Mo, W, Cr, Ni, or an alloy containing these.
(Appendix 11)
11. The micropump according to any one of appendices 1 to 10, wherein a surface of the bimetal is protected with a polymer film.
(Appendix 12)
The high temperature side member is in contact with the heat source and receives heat (21), and contact adjusting means for controlling the contact and non-contact with the displacement means by transmitting the heat received by the heat reception section to the displacement means The micropump according to appendix 1, characterized by comprising:
(Appendix 13)
The micropump according to appendix 1, wherein the low temperature side member has a channel through which a fluid passes, and performs heat exchange from the channel wall surface to the fluid.
(Appendix 14)
The micropump according to any one of appendices 1 to 6,
A semiconductor element in contact with the high temperature side member of the micropump;
A semiconductor device including a circulation system connected to the micropump to circulate the fluid.
(Appendix 15)
15. The semiconductor device according to appendix 14, further comprising a main pump connected to the circulation system.
(Appendix 16)
The semiconductor device according to appendix 14 or 15, further comprising a water jacket connected to the circulation system and in contact with a low temperature side member of the micropump.

  It can be applied to microstructured circulation channels with any heat source. For example, the present invention can be applied to a cooling system for fine electronic components. Moreover, it can be used for a semiconductor device incorporating a cooling system.

10, 110A, 110B, 110C, 200 Micro pump 20 High temperature side member 21 Heat receiving portion 22 Heat transfer portion (contact adjusting means)
25, 61 Silicon substrate 30, 230 Intermediate layer 31, 231 Bimetal first member (high CTE member)
32,232 Bimetallic second member (low CTE member)
33, 233 Diaphragm 34 Fluid introduction path 35, 235 In valve 36 Fluid discharge path 37, 237 Out valve 38 Holding part 40 Low temperature side member 41 Silicon substrate (third substrate)
50 Second substrate 51 Insulating material (permanent resist)
52 Thermal insulation (epoxy adhesive)
60 First substrate 253 Displacement means

Claims (7)

A high temperature side member having a contact surface with a semiconductor element as a heat source;
A low temperature side member located on the heat dissipation side;
An intermediate layer located between the high temperature side member and the low temperature side member;
A chamber forming a part of a flow path between the intermediate layer and the low temperature side member;
With
The intermediate layer includes a diaphragm, and displacement means for displacing the diaphragm by heat absorption from the high temperature side member and heat radiation from the low temperature side member,
The diaphragm is displaced between a first position before displacement and a second position in contact with the low temperature side member due to the displacement, thereby allowing fluid to be taken into and out of the chamber. A micro pump.   The displacement means has a first linear expansion coefficient and a first member located on the high temperature side member side, and a second linear expansion coefficient smaller than the first linear expansion coefficient and the high temperature The micropump according to claim 1, wherein the micropump is a bimetal including a side member and a second member located on the opposite side.   The micro pump according to claim 2, wherein the diaphragm is in contact with the high temperature side member at the first position.   3. The micropump according to claim 2, wherein the displacement means is a bimetal having a cantilever structure disposed between the diaphragm and the high temperature side member.   The intermediate layer further includes a first valve located in a fluid introduction path for introducing the fluid into the chamber, and a second valve located in a fluid discharge path for discharging the fluid from the chamber, the diaphragm, the first 5. The micropump according to claim 1, wherein the first valve and the second valve are integrally formed. The micropump according to any one of claims 1 to 5,
A semiconductor element in contact with the high temperature side member of the micropump;
A semiconductor device including a circulation system connected to the micropump to circulate the fluid.   The semiconductor device according to claim 6, further comprising a main pump connected to the circulation system.