WO2008038611A1

WO2008038611A1 - Gas conveying pump, method of forming heater, and sensor

Info

Publication number: WO2008038611A1
Application number: PCT/JP2007/068507
Authority: WO
Inventors: Sven Heisig; Tsuyoshi Ikehara; Takashi Mihara
Original assignee: National Institute Of Advanced Industrial Science And Technology; Olympus Corporation
Priority date: 2006-09-28
Filing date: 2007-09-25
Publication date: 2008-04-03

Abstract

A technique capable of highly accurately conveying even a slight amount of gas and highly reliable. A gas conveying pump (10) has a flow channel and a heater (20). The flow channel is composed of a chamber (12), an entrance side channel (13), an exit side channel (14), and a tapered inlet side diffuser section (15), and a tapered outlet side diffuser section (16). The heater (20) causes gas inside the chamber (12) to expand and contract, changing the volume of the chamber (12) to reliably convey the gas from the entrance side channel (13) to the exit side channel (14). The heater (20) provided in the chamber (12) is formed from silicon with boron diffused in it. Preferably, the heater (20) is made up of heater members (20a) arranged side by side so as to penetrate the inside of the chamber (12).

Description

Specification

Gas transfer pump, heater formation method, detection sensor

The present invention relates to a gas transfer pump, a detection sensor that detects molecules and the like present in an atmosphere, and the like. Background art

[0002] Conventionally, when various gases are transported, generally, a method of generating a flow of gas by a fan or the like, a method of pumping a gas by a pump or the like, or a pressure difference by a vacuum pump or the like is generally used to generate the gas. A suction method or the like is used.

However, with such a method, it is difficult to carry a very small amount of gas and to control the gas flow rate with high accuracy.

[0003] On the other hand, there is a pump of a system that drives a diaphragm with a piezoelectric element or an electrostatic actuator for transporting a liquid.

In addition, for example, a method of ejecting liquid droplets by generating bubbles by applying thermal energy to ink (liquid) in the ink jet printer technology has been proposed (for example, Patent Document 1). reference.).

With these technologies, it is possible to control the flow rate of the liquid to a very small amount and transfer it.

Yes

[0004] Patent Document 1: Japanese Patent Publication No. 61-59911

Disclosure of the invention

Problems to be solved by the invention

[0005] However, the pumps using the diaphragm as described above and the technology of the method of generating bubbles using thermal energy are for liquids, and are technologies for transporting gases at a small flow rate. Hasn't been proposed yet!

All of the above-described techniques cause the movement of the liquid by causing a pressure change in the liquid. Even if such a technology is simply applied to a gas, the density of the gas is lower than that of the liquid, so even if a pressure change similar to that of the liquid is caused, the volume change will occur. Not reached. As a result, the density of the gas is merely increased, and it becomes difficult to cause the movement of the gas. If an attempt is made to change the pressure sufficient to move the gas, the amount of change in the diaphragm or the like must be increased. In this case, it is difficult to realize continuous operation as well as intermittent operation. In addition, with the technology as described above, it is more difficult to transport a gas with a very small flow rate.

[0006] In addition, the conventional methods as described above are configured to include mechanically movable parts, except for a method of generating bubbles using thermal energy. For this reason, it is difficult to avoid a decrease in reliability due to a failure of the movable part. In addition to this, when a movable part is provided, the operating noise or heat generated by the operation may become a problem. In addition, when trying to apply such a mechanism to a sensor or the like, the operating noise, vibration, heat, etc. of the movable part may adversely affect the detection sensitivity of the sensor.

The present invention has been made on the basis of such a technical problem, and an object of the present invention is to provide a technology that can transport a gas with high accuracy even in a small amount and is excellent in reliability.

Means for solving the problem

[0007] For this purpose, the inventors have a chamber part formed in the pump, a first channel formed to communicate the chamber part and the outside of the pump, A second channel formed to communicate with a part of the chamber and the outside of the pump at a position different from the channel, and formed between the part of the chamber and the first channel, from the first channel side. It is formed between the first reduced diameter part where the inner diameter gradually decreases toward a part of the chamber, and between the chamber part and the second channel, and the inner diameter gradually decreases from the part of the chamber toward the second channel side. It has already been found that the above problem can be solved by realizing a gas transport pump having a configuration including the second reduced diameter portion and a temperature changing means for changing the temperature in a part of the chamber.

In such a gas transfer pump, the temperature in the chamber is repeatedly raised and lowered by the temperature changing means. Then, the gas expands and contracts in a part of the chamber, causing a volume change. At the time of expansion, the gas tends to come out of the chamber 1 from the first reduced diameter portion and the second reduced diameter portion formed so as to face a part of the chamber. Here, the first reduced diameter portion is the first The inner diameter gradually decreases from the channel side toward the chamber part, and the inner diameter decreases on the chamber part side, whereas the second diameter-reduced part is the second channel from the chamber part side. The inner diameter gradually decreases toward the side, and the inner diameter increases on the partial chamber side. Due to the difference in pressure loss at this portion, the gas is more likely to flow out of the second reduced diameter portion than the first reduced diameter portion. On the other hand, when the gas contracts, the gas outside the chamber 1 tries to be drawn into the chamber 1 from the first reduced diameter portion and the second reduced diameter portion. At this time, the gas is more easily drawn from the first reduced diameter portion than the second reduced diameter portion.

In other words, when the temperature in the chamber part is raised, the gas in the chamber 1 flows out to the second channel side, and when the temperature in the chamber part is lowered, the gas flows into the chamber 1 from the first channel. By repeatedly raising and lowering the temperature in a part of the chamber, gas can be conveyed from the first channel side to the second channel side. At this time, in the pump, the gas is not changed in phase and is conveyed in a gaseous state. By using temperature change, it is possible to easily generate a pressure change in the gas compared to when using a diaphragm, etc., which makes it possible to reliably transport the gas even at a very small flow rate. It becomes.

In such a gas transport pump, the first channel, the first reduced diameter portion, the chamber part, the second reduced diameter portion, and the second channel are formed on a silicon substrate, a glass substrate, or the like by a lithographic method. That power S. As a result, the gas transfer pump can be made very small, and can be mass-produced at low cost.

Furthermore, since the gas transfer pump has a very simple structure and has no moving parts, it is possible to obtain high durability and reliability that are unlikely to cause a failure or the like, and there is no operation noise.

As the temperature changing means, a device comprising a heater for causing a temperature change in a part of the chamber and a controller for changing the heat generation temperature of the heater is used.

In order to improve the performance as a pump, it is necessary to increase the discharge flow rate per unit time. There are various approaches to this, one of which is to accelerate the heating / cooling cycle in the chamber by the heater. For this purpose, the heating effect of the heater It is necessary to increase the rate.

As is well known, such a heater is generally made of metal. Metals such as Au and Pt, which have high thermal conductivity, are frequently used as heater materials. By the way, in the gas transfer pump formed by the silicon substrate as described above, the main purpose is to reduce the size and the thickness by using a semiconductor process. However, if the thickness of the force gas transfer pump is reduced, there will be no escape from the heat generated by the heater, heat dissipation will not be possible to some extent efficiently, and it will be difficult to increase the heating / cooling response to some extent. We have found that.

[0009] Therefore, the present inventors paid attention to silicon as a heater material. Silicon is made to have conductivity by diffusing impurities such as boron (B) to function as a heater.

Yes

In the gas transfer pump of the present invention thus made, the temperature changing means is composed of a heater and a controller that changes the heat generation temperature of the heater, and the heater is a silicon in which impurities are diffused. It is manufactured and arranged so as to penetrate a part of the chamber.

Thus, by forming the heater with silicon in which impurities are diffused, it is possible to increase the heat generation and heat dissipation efficiency.

[0010] In order to accelerate the heating / cooling cycle in the chamber 1, it is preferable to increase the contact area of the heater to the atmosphere in the chamber as much as possible.

Therefore, in the present invention, the heater is disposed so as to penetrate a part of the chamber. For this purpose, the heater may be supported only at both ends, and the heater may be suspended in the space in a part of the chamber. By doing so, the entire outer peripheral surface of the heater can be brought into contact with the atmosphere in a part of the chamber, so that the heat of the heater can be efficiently transferred to the atmosphere in the part of the chamber. In order to increase the contact area of the heater with the atmosphere inside the heater chamber, such a heater has a rod-shaped heater member with a plurality of rod-shaped heater members arranged side by side corresponding to the chamber part. It ’s better to do that.

In the case where the heater is formed of a thin metal, it is difficult in terms of the production process to keep it in the air in the chamber. Also metal and its heater electrode Due to the difference in the coefficient of thermal expansion of the glass substrate that supports the metal, the metal is subject to great stress and thermal strain (deformation) each time the heater is heated or cooled, and it breaks down after prolonged use. In addition, the inventors have also experienced a force S that generally needs to be relatively thin to achieve a high temperature, in which case the heat conduction is poor and the current concentrated location becomes hot and breaks down. . Also, since the metal thin film is a microcrystal, it is vulnerable to these deformations and thermal destruction. In addition, because the surface of the relatively deep chamber is in contact with air on some sides, heat transfer from the heater to the air is poor.

[0011] A heater that constitutes such a gas transport pump includes a first step of diffusing boron as an impurity in a surface layer portion of a silicon substrate that constitutes the gas transport pump, and forming a boron diffusion layer in the silicon substrate. A second step of etching the portion other than the portion constituting the heater to the lower part of the boron diffusion layer, and a third step of etching the silicon substrate below the boron diffusion layer in the portion constituting the heater. It is preferably formed by a heater forming method characterized by

In this way, the boron diffusion layer formed by silicon into which boron has diffused is formed in a state of floating / suspending in the air, and this can be used as a heater.

A heater, in order to arrange so as to pass through the space part chamber, in a first step, the surface layer portion of the silicon substrate, by diffusing boron in a concentration of 5 X 10 ¹⁸ cm- ³ or more, the In the third step, it is preferable to perform etching by using KOH having a concentration of 10 to 60%, more preferably 10 to 30% or less. A more preferred range of concentration of boron to diffuse into the surface layer portion of the silicon substrate in the first step is 2 X 10 ¹⁹ cm_ ³ or more. In this case, in the third step, the etching is performed using 3 to 30%, more preferably 3 to 15% of KOH.

[0012] Such a gas transport pump of the present invention may further include a flow rate sensor unit that detects the flow rate of the gas passing through the pump. In that case, the flow sensor unit is provided in the vicinity of the gas flow path including the first channel, the first reduced diameter part, the chamber part, the second reduced diameter part, and the second channel, It is better to detect the gas flow rate by detecting the temperature change. Furthermore, the flow sensor unit is provided in the vicinity of the first channel and / or the first reduced diameter portion and in the vicinity of the second channel and / or the second reduced diameter portion, respectively. Is preferred. And the difference of the output of each provided flow sensor part The detection is preferable because noise removal and the like can be achieved.

[0013] The gas transport pump as described above can be used in various applications. For example, in a detection sensor for detecting a specific type of substance, there is an application in which a gas containing a substance to be detected is sent to an adsorbent that adsorbs the substance, such as a molecule (gas molecule) recognition material. In this way, by forcibly sending a gas containing a substance to the adsorbent, the amount of adsorption of a specific substance on the adsorbent can be increased to improve the detection sensitivity or shorten the measurement time. Power S can be. In addition to this, it can be applied to various uses such as cooling various equipment by transporting gas and generating air flow, and the gas transport pump of the present invention particularly limits its use. There is no intention. In any case, the present invention is effective when gas is transported at a very small flow rate, and when it is desired to reduce the size and size of the gas transport pump.

The present invention includes a detection unit that detects a substance having a mass contained in a gas, and a pump unit that sends the gas to the detection unit. The pump unit sends gas from the outside to the detection unit. The main body of the pump in which the flow path is formed, the volume change generation section that causes a volume change in the gas in the flow path, and the volume change generation section when the volume change occurs in the gas, from the detection section in the flow path. A backflow prevention unit that prevents gas from moving in the direction of leaving. The volume change generation unit includes a heater and a controller that changes the heat generation temperature of the heater. The heater is made of silicon in which impurities are diffused and is disposed so as to penetrate a part of the chamber. It is characterized by that.

[0015] When a volume change occurs in the gas by the volume change generation unit, the backflow prevention unit prevents the gas from moving in the direction away from the detection unit in the flow path, so that the gas is detected in the flow path. Move towards In this way, the pump main body can send gas from the outside to the detection section through the flow path.

At this time, the pump body has a part of the chamber, the volume change generation part causes a volume change in the gas in the part of the chamber, and the inner diameter of the flow path gradually decreases in the gas moving direction as a backflow prevention part. It is preferable to form the reduced diameter portion to be formed before and after a part of the chamber. By the way, if a fine diameter-reduced portion is used for the backflow preventing portion, the flow path resistance against the gas increases. For this reason, a plurality of flow paths each having a backflow prevention unit can be provided in parallel. The In this case, the flow paths may be provided radially from the volume change generation unit or may be provided in parallel.

The invention's effect

[0016] According to the present invention, it is possible to transport gas with high accuracy even to a small amount of gas to a gas transport pump or a detection sensor, and to reduce the force and the size of the sensor. Can do. Furthermore, since it has a very simple structure and has no moving parts, it is unlikely to break down, and high durability and reliability can be obtained. In such a gas transfer pump and detection sensor, it is possible to increase the heat generation and heat dissipation efficiency by forming the heater with silicon diffused with boron, and the heating and cooling cycle in the chamber by the heater. As a result, the performance of the gas transfer pump can be improved.

Brief Description of Drawings

FIG. 1 is a diagram showing a schematic configuration of a gas transfer pump in the present embodiment, where (a) is an overall view, and (b) is an enlarged view of a main part.

FIG. 2 is a diagram showing a configuration of a gas transfer pump.

FIG. 3 is a cross-sectional view of a gas transfer pump.

FIG. 4 is a cross-sectional view showing another example of the gas transfer pump.

FIG. 5 is a perspective view showing a configuration of a heater in the present invention.

FIG. 6 is a diagram showing a heater forming method, (a) is a cross-sectional view and a plan view of the silicon substrate with the oxide film removed, and (b) is a cross-sectional view of the state after spin-coating and diffusing boron. It is a figure.

[FIG. 7] FIG. 7A is a cross-sectional view and a plan view of a state in which a silicon substrate is etched according to a heater pattern, and FIG. FIG.

FIG. 8 is a diagram showing the relationship between the concentration of KOH used for etching and the etching rate.

FIG. 9 is a diagram showing temperature rise performance data and temperature distribution in a metal heater.

FIG. 10 is a diagram showing temperature rise performance data and temperature distribution in a silicon heater.

FIG. 11 is a diagram showing an analysis result of a temperature distribution by a finite difference method. FIG. 12 is a diagram showing an example of a process for forming an inlet side channel, an outlet side channel, an inlet side diffuser portion, an outlet side diffuser portion, and a heater on the other substrate, (a) is an inlet side channel. The perspective view of the state formed by etching the outlet side channel, the inlet side diffuser part, and the outlet side diffuser part on the silicon substrate, (b) is the process following step (a)! /, The inlet side channel, the outlet It is a perspective view of the state which formed the side channel to the predetermined depth.

FIG. 13 (a) is a perspective view showing a state in which boron is diffused in a predetermined region following the step of FIG. 12 (b), and FIG. 13 (b) is a sectional view of FIG. 13 (a).

[FIG. 14] (a) is a cross-sectional view showing a state in which etching is performed to form a heater following the step of FIG. 13, and (b) is a diagram showing a chamber integrated under the heater following the step of (a). FIG. 6 is a cross-sectional view showing a state etched to form a portion.

FIG. 15 is a view showing a state in which a cavity is formed on the other substrate and bonded to one substrate.

Explanation of symbols

[0018] 10 ··· Gas transfer pump (pump part), 11 ··· Main body, 12 ··· Part of chamber, 13 ··· Inlet channel (first channel), 14 ··· Exit side Channel (second channel), 15 '' Inlet side diffuser part (first reduced diameter part, backflow prevention part), 16 ·· Outlet side diffuser part (second diameter reduction ^ backflow prevention, 20 · ··· Heater, 20 & ··· Heater age, 21 ·· = ιTorolla, 25 ····· Boron diffusion layer

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a diagram for explaining a functional configuration of the gas transport pump (pump unit) 10 in the present embodiment, and FIG. 2 is a diagram showing an actual configuration of the gas transport pump 10.

As shown in FIG. 1 and FIG. 2, a gas transfer pump 10 includes a chamber part 12 having a predetermined volume in a main body 11, and an inlet side channel (introducing gas from the outside into the chamber part 12). (First channel) 13, outlet side channel (second channel) for delivering gas from chamber part 12, inlet side diffuser section (first channel) provided between chamber part 12 and inlet side channel 13 Diameter reduction part, backflow prevention part) 15, chamber part 12 and out An outlet side diffuser portion (second reduced diameter portion, backflow prevention portion) 16 provided between the mouth side channels 14 is formed, and a heater 20 is provided in the chamber part 12. .

As shown in FIG. 3, the main body 11 is formed by bonding, for example, two substrates l la and l ib made of a Si-based material. Further, by forming a concave portion of a predetermined shape on one or both of the substrates l la and l ib, a chamber part 12, an inlet side channel 13, an outlet side channel 14, an inlet side diffuser part 15 An outlet side diffuser portion 16 is formed.

As shown in FIGS. 2 and 3, the body 11 is formed with ports 17 and 18 communicating with the inlet side channel 13 and the outlet side channel 14 and the outside, and pipes and the like can be connected thereto. Has become possible. In addition, the main body 11 can be integrated together with a sensor or a capillary for performing gas chromatography.

[0021] The chamber portion 12 has, for example, a circular cross section. An inlet side diffuser portion 15 is formed on one side of the chamber portion 12, and an outlet side diffuser portion 16 is formed on the other side.

[0022] One side of the inlet side channel 13 opens to the port 17, and the other end is the inlet side diffuser portion.

15 to communicate with. The inlet-side diffuser section 15 is formed so as to communicate the inlet-side channel 13 and the chamber part 12, and its cross-sectional area (inner diameter) gradually decreases from the inlet-side channel 13 side toward the chamber section 12 side. It has a tapered nozzle shape.

The outlet side channel 14 is formed so that one end opens to the side surface of the port 18 and the other end communicates with the outlet side diffuser portion 16. The outlet side diffuser portion 16 communicates with the chamber portion 12 and the outlet side channel 14, and is formed so as to open to the chamber portion 12 at a position different from the inlet side diffuser portion 15, and the outlet side diffuser portion 16 exits from the chamber portion 12 side. A tapered nozzle is formed with a cross-sectional area that gradually decreases toward the side channel 14 side.

As shown in FIG. 4, the inlet side diffuser portion 15 and the outlet side diffuser portion 16 are also formed from the inlet side channel 13, the chamber part 12, and the outlet side channel 14 in the thickness direction of the main body 11. Also, it is preferable to form such that the cross section is small.

In this way, the main body 11 has an inlet side diffuser portion 15 from the inlet side channel 13. A gas flow path is formed through the chamber part 12 and the outlet side diffuser 16 to the outlet side channel 14.

As shown in FIGS. 2 and 3, ports 17 and 18 are formed in the inlet side channel 13 and the outlet side channel 14 so that piping or the like can be connected thereto.

Now, as shown in FIG. 3, the heater 20 provided in the chamber part 12 is formed on one surface side of the substrate 11a or l ib, and is a power source (external to the body 11) ( (Not shown), it is electrically connected via the connecting part 20j.

As shown in FIG. 3, the heater 20 is provided in a portion corresponding to the chamber portion 12. The heater 20 is formed by diffusing a conductive material such as boron into a p-type silicon material.

As shown in FIG. 5, such a heater 20 has a so-called comb-like configuration in which a plurality of rod-shaped heater members 20a are arranged in parallel with each other in the radial direction of the chamber portion 12. . This is to increase the surface area of the heater 20, and therefore the heater member 20a has a thickness direction intermediate portion in the chamber portion 12 so that the entire outer periphery of the heater member 20a contacts the atmosphere in the chamber portion 12. It is preferable to provide it in a state where it penetrates and floats in the air in part 12 of the chamber.

[0027] Application of a voltage from a power source (not shown) to the heater 20 as described above is controlled by the controller 21 shown in FIG.

When a voltage is applied from the power source under the control of the controller 21, the heater 20 generates heat, which raises the temperature in the chamber part 12 and expands the gas. When the application of voltage to the heater 20 is stopped, the heat generation of the heater 20 is stopped, the temperature in the chamber part 12 is lowered, and the gas contracts. In the gas transfer pump 10, the heater 20 and the controller 21 function as a temperature change means and a volume change generation unit, and supply gas by utilizing expansion and contraction of gas. This will be described in detail below.

In the gas transfer pump 10, external gas is introduced from the inlet side diffuser portion 15 into the chamber portion 12 and discharged from the outlet side diffuser portion 16. When the heater 20 generates heat while the gas is introduced into the chamber part 12, the temperature in the chamber part 12 rises and the gas expands. The expanded gas then enters the inlet side diffuser 15 and the outlet side diffuser. It tries to flow out of the fuser part 16 to the outside of the chamber part 12.

At this time, as shown in FIG. 1 (b), the inlet-side diffuser portion 15 has a tapered nozzle shape in which the cross-sectional area gradually decreases from the inlet-side channel 13 side toward the chamber portion 12 side. Further, the outlet side diffuser portion 16 has a tapered nozzle shape in which the cross-sectional area gradually decreases from the chamber part 12 side toward the outlet side channel 14 side. Therefore, in the inlet side diffuser portion 15 and the outlet side diffuser portion 16, when the gas flows in a direction in which the cross-sectional area gradually decreases (hereinafter, this direction is referred to as the forward direction), the reverse direction, that is, the disconnection. The pressure loss is different from the case where the gas flows in a direction in which the area gradually increases (direct force from the outlet side channel 14 side to the inlet side channel 13 side, this direction is hereinafter referred to as the reverse direction). That is, in the inlet side diffuser portion 15 and the outlet side diffuser portion 16, the pressure loss when the gas flows in the reverse direction is larger than the pressure loss when the gas flows in the forward direction. This is because turbulent vortices are generated by the viscosity of the gas at the edges 15a and 16a of the inlet side diffuser part 15 and the outlet side diffuser part 16, thereby impairing the kinetic energy of the fluid, and as a result, the inlet side diffuser part. This is because the gas flow force at the outlet side diffuser section 16 is smoother in the forward direction than in the reverse direction.

Accordingly, when the gas in the chamber part 12 expands and flows out to the outside, the gas flows out from the outlet side diffuser part 16 having a smaller resistance (pressure loss) to the outside of the chamber part 12.

[0029] Thereafter, when the application of voltage to the heater 20 is stopped, the heat generation of the heater 20 is stopped, the temperature in the chamber portion 12 is lowered, and the gas contracts. Then, as the gas contracts, the gas tries to be introduced into the chamber part 12 from the inlet side diffuser portion 15 and the outlet side diffuser portion 16.

At this time, in the tapered nozzle-shaped inlet-side diffuser portion 15 and outlet-side diffuser portion 16, the pressure loss varies depending on the gas flow direction as described above. The gas is introduced into the interior of the chamber part 12 from the diffuser section 15 having a smaller resistance (pressure loss).

[0030] In this way, when the heater 20 is heated, the gas in the chamber part 12 expands and exits. Outflow from side diffuser section 16 to outlet side channel 14. Further, when the heater 20 is stopped, the gas in the chamber part 12 contracts and gas is introduced into the chamber part 12 from the inlet side channel 13 through the inlet side diffuser part 15. Yes.

Therefore, in the gas transport pump 10, by repeatedly heating and stopping the heater 20, the gas can be sucked from the inlet side channel 13 and can be discharged from the outlet side channel 14, thereby functioning as a pump.

For this reason, in the controller 21, the heater 20 is alternately switched on / off in a predetermined cycle. For example, the controller 21 can be controlled to repeat ON / OFF of the heater 20 in a cycle of 100 microseconds to 1 millisecond. Further, the controller 21 is preferably controlled so that the temperature change occurs in the range of room temperature to 1000 ° C., preferably room temperature to 500 ° C., when the heater 20 is turned on / off.

At this time, if the power of the heater 20 is increased, the temperature difference at ON / OFF increases, and the flow rate in the gas transfer pump 10 increases. Also, increasing the ON / OFF switching frequency decreases the flow rate. The temperature difference and the switching frequency at the time of ON / OFF may be set as appropriate according to the application target and application of the gas transfer pump 10. For example, when used in applications where gas decomposes at high temperatures, it is necessary to lower the temperature.

Furthermore, the gas transport pump 10 can also include a flow rate sensor unit 30 for measuring the flow rate of the discharged gas. The flow sensor unit 30 is disposed in the vicinity of at least one of the inlet side diffuser unit 15 and the outlet side diffuser unit 16. The flow rate sensor unit 30 is constantly applied with a constant voltage so as to be maintained at a predetermined temperature.

When the gas flows in the flow path, the temperatures of the inlet side diffuser portion 15 and the outlet side diffuser portion 16 are lowered. Along with this, the temperature of the flow sensor unit 30 also decreases, and by monitoring the change in electrical resistance at that time with the controller 21, it is possible to detect a decrease in the temperature of the inlet side diffuser unit 15 and the outlet side diffuser unit 16. The flow sensor unit 30 detects the flow rate of the gas discharged from the gas transfer pump 10 by grasping the relationship between the temperature drop and the flow rate at the inlet-side diffuser user unit 15 and outlet-side diffuser unit 16 in advance. It can be done.

[0033] Concerning the arrangement of the flow sensor unit 30 and the processing of its output signal, the sensitivity is improved. Various configurations are possible for this purpose. For example, the flow rate sensor unit 30 is provided on each of the inlet side diffuser unit 15 side and the outlet side diffuser unit 16 side, and by taking the difference between them, the absolute value of the flow rate can be detected or the noise component can be removed. It is also possible to remove noise components and draft components by taking response characteristics.

In order to form such a gas transport pump 10, for example, a pattern is formed by a lithography method on a substrate 11 a configured by laminating an oxide layer and a photoresist layer, whereby a chamber is formed. A part 12, an inlet side channel 13, an outlet side channel 14, an inlet side diffuser portion 15, an outlet side diffuser portion 16 and the like are formed.

For this, first, a pattern of the chamber part 12, the inlet side channel 13, the outlet side channel 14, the inlet side diffuser part 15, and the outlet side diffuser part 16 is formed on the oxide layer of the substrate 11a by lithography.

Subsequently, in a state where the inlet side diffuser portion 15 and the outlet side diffuser portion 16 are masked, the chamber part 12, the inlet side channel 13, and the outlet side channel 14 are formed to a predetermined depth by etching.

Further, the masks of the inlet side diffuser portion 15 and the outlet side diffuser portion 16 are removed, and the inlet side diffuser portion 15 and the outlet side diffuser portion 16 are formed to a predetermined depth by etching.

[0035] A film is formed on the other substrate l ib using a predetermined material. Then, a predetermined pattern corresponding to the heater 20, the connection portion 20j, and the flow rate sensor portion 30 is formed on these films by lithography and etching.

[0036] To form the heater 20, as shown in Fig. 6 (a), a BHF solution (NH F / HF / H 0)

The oxide film 1 lo is removed in a predetermined region 24 of the substrate 1 lb by etching using 4 2. This region 24 is a portion corresponding to the heater 20 and the connection portion 20j for connecting the heater 20 to the power source.

Then, a solution containing boron is spin-coated on the surface of the substrate rib in the region 24. Thereafter, the substrate l ib is heat-treated to diffuse boron to the surface of the substrate l ib, and the boron concentration is 5 × 10 ¹⁸ cnT ³ or more, more preferably 2 × 10 ¹⁹ cnT ³ or more, for example, 10 ² ° cm. — About ³ For example, as a solution containing boron, Tokyo Ohka Kogyo Co., Ltd.'s PBF ( When using a trade name), and in 1100 ° C, the heat treatment of 3. 5 hr, the surface layer portion 5 between m of boron substrate l ib, can be a boron concentration of about 10 ² ° cm_ ³ . As a result, as shown in FIG. 6B, a boron diffusion layer 25 in which boron is diffused is formed in the surface layer portion of the substrate ib.

Subsequently, as shown in FIG. 7 (a), in the region 24, the mask 20 is used and the heater 20 is attached by a D-RIE (Deep Reactive Ion Etching) method or the like. The portion other than the rod-shaped heater member 20a and the connecting portion 20j constituting the structure is etched to a predetermined depth (for example, 25 Hm) below the boron diffusion layer 25 of the substrate ib.

Then, as shown in FIG. 7 (b), using KOH (10% saturated solution dissolved in isopropanol at 60 ° C.), a boron diffusion layer is formed at a portion corresponding to the heater member 20a of the substrate rib. Etch 25 lower substrate l ib. As a result, in the portion corresponding to the heater member 20a, the substrate Lib below the surface boron diffusion layer 25 is removed, leaving only the boron diffusion layer 25, thereby forming the heater member 20a. Thereby, the heater member 20a is formed in a state of floating in the air.

At this time, the concentration of KOH is preferably 3 to 30%, more preferably 3 to 15%.

The concentration of KOH by adjusting, as described above, as shown in FIG. 8, at a concentration of boron and 10 ¹⁹ CM_ ³ or more parts and density 10 ¹⁹ CM_ ³ following part, the etching rate (etching speed) The difference is more than 200 times. Then, the boron diffusion layer 25 in which boron is diffused and the other portions increase the selectivity during etching, and the portion below the concentration of 10 ¹⁹ cm- ³ , that is, the substrate under the boron diffusion layer 25 l ib only is removed, the portion of the concentration of boron 10 ¹⁹ CM_ ³ on than, i.e. the remaining boron diffusion layer 25 can be satisfactorily formed a heater member 20a. Note here, when the boron is diffused at a concentration of 2 X 10 ¹⁹ cm_ ³ or more, the concentration of KOH 3 to 30% and more preferably may be 3 to 15% boron 5 X when diffused in a concentration range of less than 10 ¹⁸ CM_ ³ or 2 X 10 ¹⁹ cm- ³ is 10% to 60% to ensure obtained because the etching effect, more preferably 10 to 30% strength KOH It is preferable to use it for etching.

[0038] After such a step, the oxide film remaining on the substrate l ib is preferably removed in order to bond the substrate l ib by anodically bonding. And these substrates 11a , L ib can be bonded to form the gas transfer pump 10.

[0039] By configuring the heater 20 with silicon in which boron is diffused in this manner, the heat transfer coefficient can be increased as compared with metal heaters so far. At this time, the heater 20 is excellent in heat dissipation compared to a metal heater, and even if the heater member 20a is formed by a thin surface layer portion in which boron is diffused in the substrate rib, the heating / cooling rate is greatly increased. It is possible to improve it. Further, by forming the heater member 20a with silicon, the heater member 20a can be brought into a state of being suspended in the air, so that the entire outer periphery thereof can be brought into contact with the atmosphere in the chamber portion 12. Also in this respect, the heating / cooling cycle of the atmosphere in the chamber part 12 can be shortened. In this way, it is possible to increase the flow rate of the gas transfer pump 10 by increasing the ON / OFF switching frequency of the heater 20.

[0040] Such a gas transport pump 10 can be applied to various uses for transporting a small amount of gas. For example, in a detection sensor for detecting gas such as gas, flow control for supplying gas to the detection sensor part, semiconductor process process, minute adjustment of gas concentration in gas combustion equipment, for example, CPU cooling in mopile equipment For example, supply of refrigerant.

For example, a detection sensor for detecting a gas such as a gas can be used to detect the presence or quantitative concentration of an explosive or harmful gas. This detection sensor adsorbs specific molecules contained in the gas and detects the presence or concentration of the gas or the like by detecting the presence or absence or amount of the adsorption. Such detection sensors are installed in facilities, equipment, and equipment that handle gas, etc., and are used to control gas leakage and gas volume.

The detection sensor is also applicable to monitoring hydrogen leaks in hydrogen stations for fuel cells, vehicles, devices and equipment that use fuel cells, which have been actively developed in recent years. it can.

In addition to this, detection sensors that detect the presence or absence of adsorption by adsorbing specific molecules, or multiple types of molecules with specific characteristics or characteristics, include, for example, food freshness and component analysis. Providing a comfortable space, 'environmental control to maintain, and even It can be used for detecting the state of a living body such as a human body. In addition, by detecting various substances from the human body, exhaled breath and metabolic components of intestinal flora, etc. with high sensitivity, it is possible to monitor health conditions, perform simple screening for diseases, diagnose lifestyle-related diseases, and monitor infectious diseases. It will be possible to do things such as

[0041] Such detection sensors are roughly classified into two types.

One is to provide a molecular adsorption film (sensitivity film) that adsorbs specific molecules on the cantilever or microresonator. It is to detect. When molecules are adsorbed on the molecular adsorption film, the mass of the molecular adsorption film increases. As a result, the amount of deflection of the cantilever changes, so that the amount of change and the adsorption of specific molecules can be detected. In addition, when the mass of the molecular adsorption film increases due to molecular adsorption, the resonance frequency of the system composed of the cantilever and the molecular adsorption film changes, so that adsorption of a specific molecule can be detected from the change.

In the other method, a molecular adsorption film is provided on the crystal unit, and the adsorption of specific molecules is detected from the change in the resonance frequency of the crystal unit when molecules are adsorbed on the molecular adsorption layer.

In addition to this, it is of course possible to employ other types of detection sensors as appropriate.

[0042] By combining the gas conveyance pump 10 with such a detection sensor, the gas conveyance pump 10 collects the gas to be detected, and supplies it to the detection sensor portion, thereby detecting the detection sensor. Can be performed with high accuracy.

[0043] As described above, the gas transport pump 10 uses the thermal expansion of the gas to reliably cause a change in volume, and can reliably transport the gas even at a very small flow rate. Moreover, in order to transport the gas, only the flow path including the chamber part 12, the inlet side channel 13, the outlet side channel 14, the inlet side diffuser part 15, the outlet side diffuser part 16 and the heater 20 are provided. High mechanical reliability can be obtained because no mechanical moving parts are required. It is also possible to avoid problems such as operating noise and heat generation due to operation as in the case of having movable parts.

[0044] In addition, the gas transport pump 10 can be very small in size because of its configuration. As a result, the detection sensor and the like configured by combining the gas transport pump 10 However, it is possible to reduce the size.

Example

[0045] The operation of the gas transport pump 10 having the above-described configuration was verified by simulation. Here, the inner diameter of the chamber part 12 is 100 m, the width of the inlet channel 13 is 10 μm, the height is 20 μm, the width of the outlet 佃 J channel 14 is 10 μm, the height is 20 μm, The length of the inlet side diffuser portion 15 is 5 m, the width of the diffuser portion is 1 to 4 111, the height is 2 to 5 111, and the outlet side diffuser portion 16 has the same shape as the inlet side diffuser portion 15. In addition, the heater 20 was repeatedly cycled by flowing a 100 mA current for 100 ms and stopping it for 100 ms.

[0046] In the chamber portion 12 portion, the temperature periodically fluctuates from room temperature to 500 ° C. From the outlet side channel 14, the gas is heated once for the volume of the chamber portion 12 once. It was discharged at a rate of 3% per nozzle.

[0047] Here, a comparative study was made on the configuration of the heater.

For comparison, a heater was formed by depositing Pt on a substrate made of Nolex (registered trademark) glass. The heater was 160 ^ m long, 26 μm wide, and lOOnm thick. The heater is integrally connected to a trapezoidal connecting part with a length of 2mm, which extends from 160m to lmm. When a constant current of 100mA is passed through this heater, as shown in Fig. 9 (a), it reaches 1100K. It took 10 〃s for the temperature to rise.

As shown in Fig. 9 (b), the heater temperature rises over a range of 80 m or more on both sides across the center of the heater, totaling 160 m or more.

On the other hand, a heater was formed of silicon by the method of the present invention. This heater is a rod with a length of 200 Hm, ψ§5 μm, and a thickness of 5 m. When a constant current of 100 mA is passed through this heater, the temperature rises to 1000 K as shown in Fig. 10 (a). It took only 1 μs to rise, and the temperature rose more than 10 times faster than the heater using Pt. This is because the thermal conductivity S of silicon is more than 150 times the thermal conductivity of Pyrex.

As shown in Fig. 10 (b), the heater temperature rises over a wide range of 100 m or more on both sides and a total of 200 m or more across the center of the heater. This is Siri This is because the heater made by CON has high efficiency because it has a very large surface area in contact with the surrounding atmosphere.

Figure 11 shows the temperature distribution using a finite difference method (ANSYS) in a state where a constant current of 600 mA flows through lms when a heater is configured by arranging 12 rod-shaped heater members with the dimensions described above. Analyzed. As shown in FIG. 11, when lms passed, it was confirmed that the temperature of the heater had risen to 2000K or more and that it had sufficient heating performance.

In this way, by constructing a heater from rod-shaped heater members made of silicon, a surface area 12 times larger than that of a conventional metal heater can be secured for a chamber of the same size. It is possible to realize a heater about 10 times faster. In the present embodiment, a chamber part 12, an inlet side channel 13, an outlet side channel 14, an inlet side diffuser part 15, an outlet side diffuser part 16 and the like are formed on the substrate l ib, and the other substrate l ib Although the wiring pattern of the heater 20 and the flow rate sensor unit 30 is formed and the substrates 1 la and ib are joined to each other, the present invention is not limited to this. For example, the heater 20 and the flow rate sensor unit 30 may be separate members.

In the above embodiment, the heater 20 is formed on the upper substrate LIB and the wafer is bonded, but the heater 20 may be formed on the lower substrate 11a. In that case, the substrate 11a can be formed of silicon, and the substrate l ib can be formed of a glass substrate. Only the recess for forming the chamber part 12 may be formed in the substrate 1 lb. The production method is shown below.

First, as shown in FIG. 12 (a), the inlet side channel 13, the outlet side channel 14, and the inlet side diffuser portion 15 are formed by D-RIE until the substrate 11a reaches the Balta layer through the oxide layer of the substrate 11a. The pattern of the outlet side diffuser portion 16 is formed. The inlet side diffuser portion 15 and the outlet side diffuser portion 16 are formed to a predetermined depth (design value). Further, as shown in FIG. 12 (b), with the inlet side diffuser portion 15 and the outlet side diffuser portion 16 masked, the inlet side channel 13 and the outlet side channel 14 are set to a predetermined depth by lithography. Form. Thereafter, an oxide film of lOOnm is formed on the entire surface of the substrate 11a, and the silicon forming the substrate 1la is protected. [0050] As shown in FIG. 13 (a), a solution containing boron is used in a predetermined region 26 corresponding to the heater 20, the connection portion 20j, and the flow rate sensor portion 30 on the substrate 1 la, and the lithography method and A pattern is formed by etching. For this purpose, use a BHF solution (NH F / HF / HO) in advance.

The oxide film is removed from the predetermined region 26 of the substrate 11a by etching. Then, a solution containing boron is spin-coated on the surface of the substrate 11a. Thereafter, the substrate 11a is heat-treated to diffuse boron into a predetermined region 26 on the surface of the substrate 11a, and the boron concentration is 5 × 10 ¹⁸ cm− ³ or more, more preferably 2 × 10 ¹⁹ cm− ^3. For example, it is about 10 ² ° cm. For example, when PBF (trade name) of Tokyo Ohka Kogyo Co., Ltd. is used as a solution containing boron, boron is applied to the surface layer part of the substrate 11a 5 m by heat treatment at 1100 ° C for 3.5 hours. in the range, it may be boron concentration of about 10 ² ° cm_ ^3. As a result, as shown in FIG. 13B, a boron diffusion layer 25 in which boron is diffused is formed in a predetermined region 26 of the surface layer portion of the substrate 11a.

Subsequently, as shown in FIG. 14 (a), the portions other than the rod-shaped heater member 20a and the connection portion 20j constituting the heater 20 are diffused by boron in the substrate 11a by lithography and D-RIE. Etch to a predetermined depth below layer 25.

Then, as shown in FIG. 14 (b), using KOH (10% saturated solution dissolved in isopropanol at 60 ° C.), the boron diffusion layer 25 is formed at the portion corresponding to the heater member 20a of the substrate 11a. The lower substrate 11a is etched. Then, in the portion corresponding to the heater member 20a, the substrate 11a below the surface boron diffusion layer 25 is removed, leaving only the boron diffusion layer 25, thereby forming the heater member 20a, A chamber part 12 is formed below. Thereby, the heater member 20a is formed in a state of floating in the air.

The concentration of KOH by adjusting, as described above, as shown in FIG. 8, at a concentration of boron and 10 ¹⁹ CM_ ³ or more parts and density 10 ¹⁹ CM_ ³ following part, the etching rate (etching speed) The difference is more than 200 times. Then, the boron diffusion layer 25 in which boron is diffused and the other portions increase the selectivity during etching, and the substrate 11a below the boron diffusion layer 25 has a concentration of 10 ¹⁹ cm- ³ or less. only is removed, the concentration of boron 10 ¹⁹ CM_ ³ or more The upper portion, that is, the boron diffusion layer 25 remains, and the heater member 20a can be formed satisfactorily. Note here, when the boron is diffused at a concentration of 2 X 10 ¹⁹ cm_ ³ or more, the concentration of KOH 3 to 30% and more preferably may be 3 to 15% boron 5 X 10 ¹⁸ cm_ ³ or more

When diffused in a concentration range of less than 2 X 10 ¹⁹ cm— ³ , etching is performed using KOH at a concentration of 10 to 60%, more preferably 10 to 30% in order to ensure an etching effect. It is preferable to do so.

[0052] After such a step, it is preferable to remove the oxide film remaining on the substrate 11a in order to bond the substrate l ib together by ananodic bonding.

[0053] The substrate l ib is formed of a glass substrate such as Pyrex (registered trademark). As shown in FIG. 15, a cavity 27 slightly larger than the chamber part 12 is formed on the substrate ib. The depth of the cavity 27 is, for example, 10 m, and etching using a BHF solution can be used for the formation.

The gas transfer pump 10 can be formed by bonding such a substrate ib to the substrate 11a by ananodic bonding.

[0054] In the above-described embodiment, if the one having the same function as the force indicating the dimension example, the material example, the manufacturing method, etc. of the gas transfer pump 10 can be realized, it is limited to the category shown above. It is not a thing. In addition, the usage of the gas transfer pump 10 is not limited to the above.

[0055] Further, in the above-described embodiment, the force p-type silicon using a p-type silicon diffused with boron as a heater is not limited to ease of the production process. N-type silicon diffused with P or As may be used. In this case, it is necessary to devise another method for creating the comb heater and part of the chamber. For example, to create a silicon heater first, use a technique that uses RIE (reactive ion etching), which allows vertical processing, and then switches to plasma etching, which allows isotropic etching.

[0056] Further, in the gas transport pump 10, the force in which the inlet side channel 13 and the outlet side channel 14 are arranged in a straight line is not limited to this. The inlet side channel 13 and the outlet side channel 14 are connected to each other at a predetermined angle. Various arrangements can be made such as arrangement at a shifted position or arrangement so as to be adjacent to each other. In the above embodiment, silicon is used as the base material for forming the gas transfer pump 10. Silicon has excellent features such as high thermal conductivity, easy processing, and low cost. However, in order to form the gas transfer pump 10, a glass-based material, a plastic-based material, a ceramic-based material, or the like may be used for portions other than the heater 20. In the case of using a glass-based material or a plastic-based material, the gas transfer pump 10 may be formed using a molding technique, an imprint technique, etc. in addition to the lithography technique.

Furthermore, a silicon oxide layer is provided on the surface of the member such as the chamber part 12, the inlet side channel 13, the outlet side channel 14, the inlet side diffuser portion 15, the outlet side diffuser portion 16 and so on, and SiN is laminated. Alternatively, a coating layer may be formed by performing nitriding treatment, and the flow path resistance between the member surface and the gas may be reduced. Furthermore, the material of the coating layer on the surface can be made different depending on the type of gas used.

By the way, in the gas transport pump 10 in the above embodiment, since the fine inlet side diffuser portion 15 and the outlet side diffuser portion 16 are used, the flow path resistance against the gas is relatively large. For this reason, in order to increase the flow rate, a plurality of sets of flow paths each including the inlet side channel 13 and the inlet side diffuser portion 15, the outlet side diffuser portion 16 and the outlet side channel 14 are provided on the inlet side and the outlet side, It is also possible to expand the total flow area. In this case, the flow paths may be provided radially from the chamber part 12 or may be provided in parallel. Further, by stacking a plurality of such gas transfer pumps 10, the total flow area may be expanded.

In addition to the above, the configurations described in the above embodiments can be selected or changed to other configurations as appropriate without departing from the gist of the present invention.

Claims

The scope of the claims

[1] A pump for conveying gas,

A chamber portion formed in the pump;

A first channel formed to communicate between a portion of the chamber and the outside of the pump;

A second channel formed to communicate a part of the chamber and the outside of the pump at a position different from the first channel;

A first reduced diameter portion formed between the chamber portion and the first channel and having an inner diameter that gradually decreases from the first channel side toward the chamber portion; A second diameter-reduced portion formed between the second channels and gradually reducing the inner diameter toward the second channel side, and a temperature that changes the temperature in the chamber portion. Change means,

With

The temperature changing means includes a heater and a controller that changes the heat generation temperature of the heater,

The gas transfer pump according to claim 1, wherein the heater is made of silicon in which impurities are diffused, and is disposed so as to penetrate a space in a part of the chamber.

[2] The gas transport according to claim 1, wherein the heater is configured by arranging a plurality of rod-shaped heater members side by side in a portion corresponding to a part of the chamber! Pump.

[3] A method for forming a heater constituting the gas conveyance pump according to claim 1 or 2, wherein boron is diffused by diffusing boron as an impurity in a surface layer portion of a silicon substrate constituting the gas conveyance pump. A first step of forming a layer;

A second step of etching a portion of the silicon substrate corresponding to a portion of the chamber except for a portion constituting the heater to a position below the boron diffusion layer;

And a third step of etching the silicon substrate below the boron diffusion layer in a portion constituting the heater.

[4] In the first step, boron is added to the surface layer portion of the silicon substrate at 5 × 10 ¹⁸ cm_ ^3. Diffuse at the above concentration,

4. The method of forming a heater according to claim 3, wherein in the third step, etching is performed using KOH having a concentration of 10 to 60%.

[5] a detection unit for detecting a substance having a mass contained in the gas;

A pump unit for feeding the gas to the detection unit;

The pump unit includes a pump body in which a flow path for sending the gas to the detection unit from the outside is formed,

A volume change generating section for causing a volume change in the gas in the flow path;

A backflow prevention unit that prevents the gas from moving in a direction away from the detection unit in the flow path when a volume change occurs in the gas by the volume change generation unit;

The volume change generation unit includes a heater and a controller that changes the heat generation temperature of the heater,

The detection sensor according to claim 1, wherein the heater is made of silicon in which impurities are diffused, and is arranged to pass through the space of the volume change generation unit! /.

6. The detection sensor according to claim 5, wherein the heater is configured by arranging a plurality of rod-shaped heater members in a portion corresponding to the volume change generation portion.