JP2012208061A - Flow sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow sensor having a high reliability.SOLUTION: A flow sensor comprises: a first substrate 1 of which top surface is provided with a recess 8; a heating element 6 disposed in such a manner that it covers a part of the recess 8 of the first substrate 1; a protecting member 40 which protects the heating element 6; and a second substrate 14 which is disposed in such a manner that it covers the recess 8 of the first substrate 1 and the heating element 6 and is provided with an inflow port and an outflow port which respectively communicate with the recess 8 of the first substrate 1.

Description

  The present invention relates to a fluid inspection technique and relates to a flow sensor.

  In gas piping or the like, it is important to accurately measure the gas flow rate. There is a flow sensor as a device for measuring the flow rate of a fluid such as gas. In order to eliminate the necessary work as much as possible when installing the flow sensor on the pipe, a flow sensor has been proposed that has a package function to facilitate installation on the pipe (for example, patents). Reference 1).

JP 2009-109349 A

  However, the conventional flow sensor has a problem that it is weak against active gas or the like and has low reliability. Therefore, an object of the present invention is to provide a highly reliable flow sensor.

  As a result of intensive studies, the present inventor has found that a conventional flow sensor using a heating element is weak against an active gas or the like because the heating element is exposed to the fluid to be measured. Therefore, according to an aspect of the present invention, (a) a first substrate provided with a recess on the upper surface, (b) a heating element disposed so as to cover a part of the recess of the first substrate, c) a protective member that protects the heat generating element; and (d) a first member that is disposed so as to cover the concave portion and the heat generating element of the first substrate, and is provided with an inlet and an outlet that respectively communicate with the concave portion of the first substrate. There is provided a flow sensor comprising two substrates.

  According to the present invention, a highly reliable flow sensor can be provided.

It is a top view of the flow sensor which concerns on the 1st Embodiment of this invention. It is sectional drawing seen from the II-II direction of FIG. 1 of the flow sensor which concerns on the 1st Embodiment of this invention. It is sectional drawing seen from the III-III direction of FIG. 1 of the flow sensor which concerns on the 1st Embodiment of this invention. It is a 1st process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 2nd process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 3rd process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 4th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 5th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 6th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 7th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is an 8th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 9th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 10th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is an 11th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is a 12th process sectional view of the flow sensor concerning a 1st embodiment of the present invention. It is sectional drawing of the flow sensor which concerns on the 2nd Embodiment of this invention. It is a 1st process sectional view of the flow sensor concerning a 2nd embodiment of the present invention. It is a 2nd process sectional view of the flow sensor concerning a 2nd embodiment of the present invention. It is a 3rd process sectional view of the flow sensor concerning a 2nd embodiment of the present invention. It is a 4th process sectional view of the flow sensor concerning a 2nd embodiment of the present invention. It is sectional drawing of the flow sensor which concerns on the 3rd Embodiment of this invention. It is a 1st process sectional view of the flow sensor concerning a 3rd embodiment of the present invention. It is a 2nd process sectional view of the flow sensor concerning a 3rd embodiment of the present invention. It is a process bottom view of a flow sensor concerning a 3rd embodiment of the present invention. It is a 3rd process sectional view of the flow sensor concerning a 3rd embodiment of the present invention. It is a 4th process sectional view of the flow sensor concerning a 3rd embodiment of the present invention. It is a 5th process sectional view of the flow sensor concerning a 3rd embodiment of the present invention. It is a 6th process sectional view of the flow sensor concerning a 3rd embodiment of the present invention. It is 1st process sectional drawing of the flow sensor which concerns on the modification of the 3rd Embodiment of this invention. It is 2nd process sectional drawing of the flow sensor which concerns on the modification of the 3rd Embodiment of this invention. It is sectional drawing of the flow sensor which concerns on the 4th Embodiment of this invention. It is a 1st process sectional view of the flow sensor concerning a 4th embodiment of the present invention. It is a 2nd process sectional view of the flow sensor concerning a 4th embodiment of the present invention. It is a 3rd process sectional view of the flow sensor concerning a 4th embodiment of the present invention. It is a 4th process sectional view of the flow sensor concerning a 4th embodiment of the present invention. It is a 5th process sectional view of the flow sensor concerning a 4th embodiment of the present invention. It is sectional drawing of the flow sensor which concerns on other embodiment of this invention.

  Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(First embodiment)
As shown in FIGS. 1 to 3, the flow sensor according to the first embodiment covers the first substrate 1 provided with the recess 8 on the upper surface and a part of the recess 8 of the first substrate 1. The heating element 6 arranged in this way, the protective member 40 protecting the heating element 6, the recess 8 of the first substrate 1 and the heating element 6 are arranged so as to cover the recess 8 of the first substrate 1, respectively. And an inflow port 12 and a second substrate 14 provided with the outflow port 13.

  As a material of the first substrate 1, Pyrex (registered trademark) glass or the like can be used. A recess 8 is provided in the first substrate 1, and the heating element 6 is held in a bridge shape on both sides of the recess 8. A silicon filament can be used for the heating element 6. The first substrate 1 is provided with through-electrodes 2 and 3 penetrating from the bottom surface to the top surface with the metal film 9 interposed therebetween. The through electrodes 2 and 3 are in contact with the heating element 6 via the metal film 9 on both sides of the recess 8 of the first substrate 1.

  A protective member 40 such as a passivation film covers the entire surface of the heating element 6. For example, as the material of the protective member 40, an organic material such as a fluorine-based resin and an inorganic material such as silicon oxide (SiO) and silicon nitride (SiN) can be used.

  Pyrex (registered trademark) glass or the like can also be used as the material of the second substrate 14. A recess 11 is provided on the bottom surface of the second substrate 14. The first substrate 1 and the second substrate 14 are coupled by, for example, thermocompression bonding. As a result, a fluid chamber is formed around the heat generating element 6. The fluid chamber includes the recess 8 provided in the first substrate 1 and the recess 11 provided in the second substrate 14.

  A fluid is injected into the fluid chamber through an inlet 12 provided in the second substrate 14. The injected fluid flows above and below the heat generating element 6 and is discharged to the outside of the flow sensor through the outlet 13 provided in the second substrate 14.

  Here, when a voltage is applied between the through electrodes 2 and 3, a current flows through the heating element 6 and Joule heat is generated. The heat generated by the heating element 6 is deprived according to the flow rate of the fluid injected into the flow sensor. The electrical resistance of the heating element 6 correlates with the heating temperature of the heating element 6. Therefore, it is possible to measure the change in the heat generation temperature of the heat generating element 6 by measuring the change in the electrical resistance of the heat generating element 6, and consequently measure the change in the flow velocity of the fluid flowing around the heat generating element 6. It becomes possible.

  Next, a method for manufacturing the flow sensor according to the first embodiment will be described.

  First, a first substrate 1 is prepared, and a recess 8 is provided on the upper surface of the first substrate 1 by an etching method or the like as shown in FIG. Next, as shown in FIG. 5, through holes 16 and 17 are provided in the first substrate 1 by a sandblast method or the like. Further, as shown in FIG. 6, a silicon substrate 18 is prepared, and a boron high concentration layer 19 is formed on the surface of the silicon substrate 18 by epitaxial growth. Next, as shown in FIG. 7, the boron high concentration layer 19 is shaped to an appropriate size by an etching method or the like.

  As shown in FIG. 8, the first substrate 1 and the boron high concentration layer 19 are bonded by anodic bonding so that the boron high concentration layer 19 covers a part of the recess 8 and the through holes 16 and 17. . Note that the first substrate 1 and the boron high concentration layer 19 may be directly bonded. Next, the silicon substrate 18 is removed using an alkaline solution such as hydrazine or tetramethylammonium hydroxide (TMAH), and the boron high-concentration layer 19 is used as the heating element 6 as shown in FIG. Thereafter, as shown in FIG. 10, the surface of the heating element 6 is formed by any method such as spin coating, dipping, sputtering, vapor deposition, chemical vapor deposition (CVD), or atomic layer deposition (ALD). A protective member 40 is formed on the substrate.

  A second substrate 14 is prepared, and as shown in FIG. 11, the recess 11 is provided on the bottom surface of the second substrate 14 by an etching method or the like. Further, as shown in FIG. 12, the inlet 12 and the outlet 13 are provided in the second substrate 14 by a sandblast method or the like. Next, as shown in FIG. 13, the 1st board | substrate 1 with which the heat generating element 6 is arrange | positioned, and the 2nd board | substrate 14 are couple | bonded by thermocompression bonding. Thereafter, as shown in FIG. 14, a metal film 9 is formed on the bottom surface of the first substrate 1 and the insides of the through holes 16 and 17 by sputtering or the like.

  As shown in FIG. 15, the metal film 9 is divided and electrically separated by processing the grooves 10 in the first substrate 1 by a dicing method or the like. Thereafter, the through holes 16 and 17 are filled with metal to form the through electrodes 2 and 3 shown in FIG. 2 that respectively energize the heating elements 6, and the flow sensor manufacturing method according to the first embodiment is performed. finish. The separation / division of the metal film 9 can also be performed by photolithography or a hard mask.

  According to the flow sensor according to the first embodiment described above, since the heating element 6 is covered with the protective member 40, not only the inactive fluid but also the flow rate of the active fluid is stably measured. It becomes possible to do. In addition, the withstand voltage can be improved by covering the heating element 6 with the protective member 40. Furthermore, by covering the heat generating element 6 with the protective member 40, it is possible to suppress the drift of the output of the heat generating element 6 due to the adhesion of dust.

(Second Embodiment)
As shown in FIG. 16, in the flow sensor according to the second embodiment, the heating element 7 is embedded in a glass substrate 41 as a protective member. The glass substrate 41 in which the heating element 7 is embedded is bonded to the glass substrate 42. The glass substrate 42 is provided with through electrodes 106 and 206. The heating element 7 is electrically connected to the through electrodes 2 and 3 of the first substrate 1 through the through electrodes 106 and 206 of the glass substrate 42. Other components of the flow sensor according to the second embodiment are the same as those of the flow sensor according to the first embodiment.

  When manufacturing the flow sensor according to the second embodiment, a glass substrate 41 provided with a recess is prepared, and the recess of the glass substrate 41 is filled with a conductive material. As shown in FIG. Is formed inside the glass substrate 41. Further, a glass substrate 42 provided with through holes is prepared, and the through holes of the glass substrate 42 are filled with a conductive material, so that the through electrodes 106 and 206 are formed on the glass substrate 42 as shown in FIG. After that, as shown in FIG. 19, the glass substrate 41 and the glass substrate 42 are bonded so that the heating element 7 and the through electrodes 106 and 206 are in electrical contact. Further, as shown in FIG. 20, the heating element 7 sandwiched between the glass substrates 41 and 42 is disposed on the first substrate 1 processed in the same manner as the flow sensor manufacturing method according to the first embodiment. . Thereafter, the flow sensor according to the second embodiment is manufactured by the same process as that of the first embodiment.

  By sandwiching the heating element 7 shown in FIG. 16 made of silicon filament or the like between the glass substrates 41 and 42, the mechanical strength of the flow sensor can be increased. Further, since the heating element 7 is covered with the hard glass substrates 41 and 42, it is easy to form the through electrodes 2 and 3 on the first substrate 1. In addition, you may protect the heat generating element 7 with a sapphire substrate etc. instead of a glass substrate.

(Third embodiment)
As shown in FIG. 21, in the flow sensor according to the third embodiment, the heating element 37 is embedded in a glass substrate 44 as a protective member in contact with the first substrate 1. A flat glass substrate 43 is pasted on the glass substrate 44 in which the heating elements 7 are embedded. The glass substrate 44 is provided with through electrodes 126 and 226. The heating element 7 is electrically connected to the through electrodes 2 and 3 of the first substrate 1 through the through electrodes 126 and 226 of the glass substrate 44. Other components of the flow sensor according to the third embodiment are the same as those of the flow sensor according to the second embodiment.

  When manufacturing the flow sensor according to the third embodiment, first, a flat glass substrate 43 is prepared as shown in FIG. Next, as shown in FIG. 23, a metal film to be the heating element 37 is formed on the bottom surface of the glass substrate 43 by sputtering or vapor deposition. As shown in FIG. 24, in order to secure the length of the heating element 37, the heating element 37 may be shaped into a meander shape by a photolithography method and an etching method.

  As shown in FIG. 25, a glass substrate 44 provided with a recess and two through holes is prepared. Next, as shown in FIG. 26, the glass substrate 44 and the glass substrate 43 are bonded by direct bonding so that the heating element 37 is stored inside the recess of the glass substrate 44. Thereafter, as shown in FIG. 27, the through holes of the glass substrate 44 are filled with a conductive material, and through electrodes 126 and 226 that are in electrical contact with the heating elements 37 are formed on the glass substrate 44. Further, as shown in FIG. 28, the heating element 7 sandwiched between the glass substrates 43 and 44 is disposed on the first substrate 1 processed in the same manner as the flow sensor manufacturing method according to the first embodiment. . Thereafter, the flow sensor according to the third embodiment is manufactured by the same process as that of the first embodiment.

  Also in the flow sensor according to the third embodiment, it is possible to improve the mechanical strength.

(Modification to the third embodiment)
A method for manufacturing a flow sensor according to a modification of the third embodiment will be described. First, as in the third embodiment, as shown in FIG. 26, the glass substrate 44 and the glass substrate 43 are directly bonded so that the heating element 37 is housed in the recess of the glass substrate 44. Connect by. Next, without forming the through electrode on the glass substrate 44, as shown in FIG. 29, the glass substrate 43 is formed on the first substrate 1 processed in the same manner as the flow sensor manufacturing method according to the first embodiment. , 44 is disposed between the heating elements 7. The two through holes of the glass substrate 44 communicate with the through holes 16 and 17 of the first substrate 1, respectively. Thereafter, the two through holes of the glass substrate 44 and the through holes 16 and 17 of the first substrate 1 are filled with a conductive material, and each of the through holes extends from the bottom surface of the first substrate 1 to the heating element 7 as shown in FIG. Through electrodes 102 and 103 are formed.

  Since the heat generating element 7 is protected by the glass substrate, it is easy to form the through electrodes 102 and 103 that penetrate from the bottom surface of the first substrate 1 directly to the heat generating element 7, respectively.

(Fourth embodiment)
As shown in FIG. 31, in the flow sensor according to the fourth embodiment, the heating element 37 is sandwiched between a flat glass substrate 46 disposed on the first substrate 1 and a flat glass substrate 43. It is. Further, the heating element 37 is surrounded by a filling member 47 between the glass substrate 46 and the glass substrate 43. The glass substrate 46 is provided with through electrodes 126 and 226. The heating element 7 is electrically connected to the through electrodes 2 and 3 of the first substrate 1 through the through electrodes 126 and 226 of the glass substrate 46. Other components of the flow sensor according to the fourth embodiment are the same as those of the flow sensor according to the second embodiment.

  When manufacturing the flow sensor according to the fourth embodiment, first, as shown in FIG. 32, a glass substrate 46 provided with two through holes is prepared. Next, as described in FIG. 23, a glass substrate 43 having a heating element 37 formed on the bottom surface is prepared, and the bottom surface of the heating element 37 and the upper surface of the glass substrate 46 are bonded together as shown in FIG. . Thereafter, an adhesive or molten glass frit is filled between the glass substrate 46 and the glass substrate 43 to form a filling member 47 as shown in FIG.

  As shown in FIG. 35, the through holes of the glass substrate 46 are filled with a conductive material, and through electrodes 126 and 226 that are in electrical contact with the heating elements 37 are formed on the glass substrate 44. Furthermore, as shown in FIG. 36, the heating element 7 sandwiched between the glass substrates 43 and 46 is arranged on the first substrate 1 processed in the same manner as the flow sensor manufacturing method according to the first embodiment. . Thereafter, the flow sensor according to the fourth embodiment is manufactured by the same process as that of the first embodiment.

  Also in the flow sensor according to the fourth embodiment, it is possible to improve the mechanical strength.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, embodiments, and operation techniques should be apparent to those skilled in the art. For example, as shown in FIG. 37, when the heating element 7 is covered with a hard protective member such as a glass substrate 41, 42, the through-electrode is not provided on the first substrate 1, and the heating element 7 is formed by the wires 116, 216. It may be energized. As a result, the manufacturing cost of the flow sensor can be reduced. Thus, it should be understood that the present invention includes various embodiments and the like not described herein.

DESCRIPTION OF SYMBOLS 1 1st board | substrate 2, 3 Through-electrode 6, 7, 37 Heating element 8, 11 Recess 9 Metal film 10 Dicing groove 12 Inlet 13 Outlet 14 Second board | substrate 16, 17 Through-hole 18 Silicon substrate 19 Boron high concentration Layer 40 Protective member 41, 42, 43, 44, 46 Glass substrate 47 Filling member 102, 103, 106, 206, 126, 226 Through electrode 116, 216 Wire

Claims (6)

A first substrate having a recess on the upper surface;
A heating element arranged to cover a part of the recess of the first substrate;
A protective member for protecting the heating element;
A second substrate provided so as to cover the concave portion of the first substrate and the heating element, and provided with an inlet and an outlet that respectively communicate with the concave portion of the first substrate;
A flow sensor comprising:   The flow sensor according to claim 1, wherein at least two through holes are provided in the first substrate, and the heating element is exposed from the through holes.   The flow sensor according to claim 2, further comprising a wiring connected to the heat generating element through the at least two through holes of the first substrate.   The flow sensor according to claim 1, wherein the protective member is a glass substrate.   The flow sensor according to claim 1, wherein the protective member is a sapphire substrate.   The flow sensor according to claim 1, wherein the protective member is a passivation film.

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