JP4913866B2 - Sensitive sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sensitive sensor having a sensitive film sensitive to a specific substance such as a gas sensor and a method for manufacturing the same.

  In Japanese Patent Laid-Open No. 5-281177 (Patent Document 1), a pair of thin film counter electrodes opposed to each other with an interval between them on an insulating substrate, and a pair of one end connected to the pair of thin film counter electrodes A sensitive sensor formed with a thin film wiring pattern is shown. Each of the pair of thin film counter electrodes has an elongated basic electrode portion and one or more linear electrode portions extending from the basic electrode portion. A pair of thin film counter electrodes are formed such that one or more linear electrode portions of one thin film counter electrode and one or more linear electrodes of the other thin film counter electrode are alternately arranged at equal intervals. Yes. In this type of sensitive sensor, a gas concentration and humidity are measured by measuring a resistance value between a pair of thin film counter electrodes.

In JP-A-2006-47276 (Patent Document 2), an uncured sensitive film formed by dropping a sensitive liquid so as to straddle a pair of thin film counter electrodes is heated and cured using a dispenser to detect the sensitivity of the sensitive sensor. Techniques for forming films are shown.
JP-A-5-281177 JP 2006-47276 A

  However, when the technique shown in Patent Document 2 is applied to a sensitive sensor as shown in Patent Document 1 and the sensitive liquid is dropped using a dispenser so as to straddle the pair of thin film counter electrodes, the sensitive liquid spreads concentrically. A circular uncured sensitive film is formed. Therefore, due to the difference between the contour shape of the pair of thin film counter electrodes and the contour shape of the uncured sensitive film, a part of the pair of thin film counter electrodes protrudes from the uncured sensitive film. Therefore, the area occupied by the pair of thin film counter electrodes has to be increased. Further, the sensitive film thus formed has a problem in that the thickness dimension varies, and when the sensitive sensor is mass-produced, the detection accuracy of the sensitive sensor varies.

  An object of the present invention is to reduce the difference between the contour shape of the occupied portion occupied by the pair of thin film counter electrodes and the contour shape of the occupied portion occupied by the sensitive film, and to prevent variation in detection accuracy of the sensitive sensor. It is to provide a sensitive sensor capable of

  Another object of the present invention is to provide a sensitive sensor and a method for manufacturing the same, which can form the dimension and shape of the sensitive film as accurately as possible to prevent variation in the sensitive accuracy.

  The sensitive sensor to be improved by the present invention includes an insulating substrate, a pair of thin film counter electrodes formed on the insulating substrate and opposed to each other with a space therebetween, and one end of the pair of thin film counter electrodes. It has a pair of connected thin film wiring patterns and a sensitive film formed across a pair of counter electrodes. And the uncured sensitive film | membrane formed by dripping the sensitive liquid so that a sensitive film may straddle a pair of thin film counter electrode is hardened | cured and formed. Here, the sensitive liquid spreads concentrically after dropping to form an uncured sensitive film having a circular planar contour shape. Curing includes curing caused by volatilizing a solvent by heating or natural standing and curing by baking. In the present invention, one thin film counter electrode of the pair of thin film counter electrodes has an arc shape formed so as to follow a virtual annular shape. Then, the other thin film counter electrode of the pair of thin film counter electrodes is surrounded by one thin film counter electrode and is located at the center of the virtual annular shape. The virtual annular shape here includes a virtual circle, a virtual ellipse, a virtual polygon approximate to a circle, and the like. Moreover, the arc shape here includes not only a curve but also an arc in which straight lines having one or more corners are combined.

  The sensitive liquid spreads concentrically after dropping, and the planar contour shape becomes a circular shape. Therefore, as in the present invention, when one thin film counter electrode of the pair of thin film counter electrodes has an arc shape formed along the virtual annular shape, the contour shape of the occupied portion of one thin film counter electrode, Since the contour shape of the occupying portion occupied by the sensitive film is close to an annular shape, there is no significant difference between the sizes of the two. However, the above-mentioned uncured sensitive film has a thin dome shape with a raised central part, and the thickness dimension tends to vary at the central part of the uncured sensitive film. Therefore, if the sensitive film portion at the center of the sensitive film obtained by curing the uncured sensitive film is also used, the accuracy of the sensitive sensor varies. Therefore, in the present invention, the other thin film counter electrode is surrounded by one thin film counter electrode and positioned at the center of the virtual annular shape. In this way, the sensitive film portion (peripheral portion) positioned between one thin film counter electrode and the other thin film counter electrode is the sensitive film portion (center portion) positioned on the other thin film counter electrode. ) Variation in thickness dimension is smaller. And the part of the sensitive film | membrane located on the other thin film counter electrode does not contribute to measurement substantially. Therefore, when configured as in the present invention, variations in the accuracy of the sensitive sensor can be suppressed.

  A heater for heating the sensitive film can be built in the insulating substrate. When the sensitive film is heated by the heater in this way, it is possible to prevent moisture and gas from adhering to the sensitive film more than necessary, and the accuracy of the sensitive sensor can be increased. In this case, it is preferable to form a hole penetrating the other thin film counter electrode in the center of the other thin film counter electrode. The planar contour shape of the other thin film counter electrode and the hole has an annular shape concentric with the virtual annular shape. In this way, the vertical distortion of the insulating base due to the heat of the heater can be suppressed, and damage to the insulating base and the heater can be prevented.

  A dimension L1 between one thin film counter electrode of the pair of thin film counter electrodes and the other thin film counter electrode, and a dimension L2 between the other thin film wiring pattern of the pair of thin film counter electrodes and the one thin film counter electrode. Preferably they are equal. In this way, the sensitive film portion positioned between one thin film counter electrode and the other thin film counter electrode has the same size, and it is possible to further suppress variation in the accuracy of the sensitive sensor.

  The virtual annular shape may be a virtual circle, and the other thin film counter electrode and the planar contour shape of the hole may have a similar shape concentric with the virtual circle. In this case, the radius R1 of the hole is preferably 30 to 90% of the radius R2 of the other thin film counter electrode. If it is less than 30%, the vertical distortion of the insulating substrate cannot be sufficiently suppressed. On the other hand, if it exceeds 90%, the adhesiveness between the sensitive film and the other thin film counter electrode is lowered, and the resistance value of the sensitive film may vary.

  The sensitive film can be, for example, a gas sensitive film whose resistance value changes when gas is absorbed.

  In the present invention, the other thin film counter electrode of the pair of thin film counter electrodes may also be formed in an arc shape so as to be along the virtual annular shape and to be opposed to the one thin film counter electrode. In that case, since a large space is formed between the pair of thin film counter electrodes, the thin film conductive portion is formed in the center portion of the virtual annular shape with a space between the pair of thin film counter electrodes.

  As described above, when the pair of thin film counter electrodes have an arc shape formed so as to be opposed to each other along the virtual annular shape, the contour shape of the occupied portion of the pair of thin film counter electrodes and the occupation occupied by the sensitive film Since the contour shapes of the portions are both close to an annular shape, there is no significant difference between the sizes of the two. In addition, since the thin-film conductive portion is formed at the center portion of the virtual annular shape (the central portion of the sensitive film) with a space between the pair of thin-film counter electrodes, from one thin-film counter electrode of the pair of thin-film counter electrodes Most of the current flowing through the other thin film counter electrode flows through the path of one thin film counter electrode → part of the sensitive film → thin film conductive portion → part of the sensitive film → the other thin film counter electrode. The sensitive film portion (peripheral portion) positioned between the thin film counter electrode and the thin film conductive portion has a smaller variation in thickness than the sensitive film portion (center portion) positioned on the thin film conductive portion. And the part of the sensitive film | membrane located on a thin film conductive part does not contribute to a measurement substantially. Therefore, when configured as in the present invention, variations in the accuracy of the sensitive sensor can be suppressed.

  When the above-mentioned virtual annular shape is a virtual circle or a virtual ellipse, the planar contour shape of the thin film conductive portion can be formed so as to have a similar shape concentric with the virtual circle or the virtual ellipse. In this way, a part of the sensitive film through which the current flowing from one thin film counter electrode to the other thin film counter electrode of the pair of thin film counter electrodes is substantially arc-shaped. Therefore, the variation in the thickness of the sensitive film part through which the current flowing from one thin film counter electrode to the other thin film counter electrode of the pair of thin film counter electrodes is made extremely small, resulting in variations in the accuracy of the sensitive sensor. Can be suppressed.

  The sensitive sensor of the present invention can be applied to various sensors. For example, a heater for heating the sensitive film can be built in, and the sensitive film can be a gas sensitive film whose resistance value changes when gas is absorbed. In this way, gas detection can be performed reliably.

  The pair of thin film counter electrodes has a resistance that resists the spread of the uncured sensitive film so as to prevent the uncured sensitive film from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes face each other. A structure can be formed. Thus, when the resistance generating structure is formed, when the sensitive liquid is dropped to form the uncured sensitive film, the resistance generating structure causes the uncured sensitive film to be opposite to the direction in which the pair of thin film counter electrodes face each other. Spreading in the direction of is suppressed. Therefore, even if the area of the sensitive film is designed to be small, the size and shape of the sensitive film can be formed as accurately as possible. As a result, when the gas sensor is mass-produced, it is possible to suppress variation in the gas sensitivity accuracy.

  Various resistance generating structures can be employed. For example, it is fixed to the upper surface of a pair of thin film counter electrodes, protrudes in a direction away from the insulating substrate, and continues along the edge of the thin film counter electrode located in the direction opposite to the direction in which the pair of thin film counter electrodes are opposed. The resistance generating structure can be constituted by one or more dam portions formed by a thin film extending in the direction. In this way, when the sensitive liquid is dropped to form the uncured sensitive film, the uncured sensitive film spreads in a direction opposite to the direction in which the pair of thin film counter electrodes face each other due to the weir portion. The uncured sensitive film is suppressed and has a disk shape with the center portion raised in contact with the weir portion. Therefore, it is possible to reliably suppress the spread of the uncured sensitive film and to make the outer periphery of the sensitive film along the dam part.

  Also, it is fixed to the upper surface of the pair of thin film counter electrodes and protrudes away from the insulating substrate, and is discontinuous along the edge of the thin film counter electrode located in the direction opposite to the direction in which the pair of thin film counter electrodes are opposed to each other The resistance generating structure can also be constituted by one or more protrusions formed by a thin film extending in the direction. In this way, when the sensitive liquid is dropped to form the uncured sensitive film, the outer periphery of the uncured sensitive film is formed into one or more protrusions (discontinuous protrusions) due to the surface tension of the sensitive liquid. Will be along. If such discontinuous protrusions are formed, the amount of material of the resistance generating structure can be reduced.

  Alternatively, the resistance generating structure can be constituted by a plurality of protrusions that are fixed to the upper surfaces of the pair of thin film counter electrodes, protrude in a direction away from the insulating base, and are dispersed on the thin film counter electrode and formed by a thin film. In this way, when the sensitive liquid is dropped to form an uncured sensitive film due to the step between the pair of thin film counter electrodes and the plurality of protrusions, the sensitive liquid and the pair that flow on the pair of thin film counter electrodes are dropped. The resistance with the thin film counter electrode increases.

  An output extraction electrode can be formed on a part of the pair of thin film wiring patterns. In this case, it is preferable to form the extraction electrode and the resistance generating structure with the same material. In this way, the resistance generating structure can be formed simultaneously in the process of forming the extraction electrode, and the formation of the resistance generating structure is facilitated.

  The pair of thin film counter electrodes can be formed from platinum, and the extraction electrode and the resistance generating structure can be formed from gold. If such a material is selected, the pair of thin film counter electrodes and extraction electrodes can be stabilized thermally, chemically, and electrically.

  The resistance generating structure can be configured to further include a plurality of recesses that are opened on the upper surfaces of the pair of thin film counter electrodes and are dispersed in the thin film counter electrodes. In this way, when the sensitive liquid is dropped to form an uncured sensitive film, the multiple recesses increase the resistance between the sensitive liquid flowing on the pair of thin film counter electrodes and the pair of thin film counter electrodes. The uncured sensitive film is prevented from spreading in the direction opposite to the direction in which the pair of thin film counter electrodes face each other. The resistance generating structure may be configured only from a plurality of recesses.

  In the method of manufacturing a sensitive sensor to be improved by the invention of the present application, first, a pair of thin film counter electrodes facing each other with a gap between each other and one end of each pair are connected to the pair of thin film counter electrodes by sputtering. A pair of thin film wiring patterns is formed on the insulating substrate. Next, an output extraction electrode is formed on part of the pair of thin film wiring patterns. Then, the uncured sensitive film formed by dropping the sensitive liquid so as to straddle the pair of thin film counter electrodes is cured to form the sensitive film. In this invention, it fixes to the upper surface of a pair of thin film counter electrode, protrudes in the direction away from an insulating base | substrate, and suppresses that an unhardened sensitive film spreads in the direction opposite to the direction where a pair of thin film counter electrode opposes. As described above, the resistance generating structure that is resistant to the spread of the uncured sensitive film is simultaneously formed by sputtering using the same material as the extraction electrode. According to the manufacturing method of the present invention, since the resistance generating structure can be formed at the same time in the step of forming the extraction electrode, the resistance generating structure can be easily formed.

  The resistance generating structure includes one or more dam portions formed by a thin film continuously extending along an edge of the thin film counter electrode positioned in a direction opposite to the direction in which the pair of thin film counter electrodes are opposed to the thin film counter electrode. It can be composed of one or more protrusions formed by a thin film extending discontinuously along the plurality, or a plurality of protrusions formed by a thin film dispersed on the thin film counter electrode.

  Further, in the present invention, when the pair of thin film counter electrodes are formed in an arc shape formed so as to be opposed to each other along the virtual annular shape, first, a pair of facing each other with a gap therebetween by sputtering. The thin film counter electrode and a pair of thin film wiring patterns each having one end connected to the pair of thin film counter electrodes are formed on the insulating substrate. Next, the uncured sensitive film formed by dropping the sensitive liquid so as to straddle the pair of thin film counter electrodes is cured to form a sensitive film. In the present invention, an opening is formed on the upper surface of the pair of thin film counter electrodes and dispersed along the thin film counter electrode, so that the uncured sensitive film is prevented from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes face each other. In addition, a resistance generating structure composed of a plurality of recesses that resists the spread of the uncured sensitive film is formed simultaneously with the pair of thin film counter electrodes. According to the manufacturing method of the present invention, since the resistance generating structure (a plurality of recesses) can be formed simultaneously in the step of forming the pair of thin film counter electrodes, the resistance generating structure can be easily formed.

  Moreover, you may form both a some recessed part and one or more dam parts. A plurality of recesses can be formed simultaneously when forming a pair of thin film counter electrodes, and one or more dam portions can be formed simultaneously by sputtering with the same material as the extraction electrode. Therefore, it is possible to easily form a sensitive sensor that effectively suppresses the uncured sensitive film from spreading in the direction opposite to the direction in which the pair of thin film counter electrodes face each other.

It is sectional drawing which represented typically the sensitive sensor of one embodiment of this invention applied to the gas sensor. It is the partial top view which looked at the center part of the gas sensor of FIG. 1 from upper direction. FIG. 3 is an enlarged view (sectional view taken along the line III-III in FIG. 2) of the central portion of the gas sensor in FIG. It is a figure which shows the test result which investigated the effect of the hole formed in the other thin film counter electrode. It is sectional drawing which represented typically the sensitive sensor of other embodiment of this invention applied to the gas sensor. It is the fragmentary top view which looked at the center part of the sensitive sensor of other embodiment of this invention applied to the gas sensor from upper direction. It is the VII-VII sectional view taken on the line of FIG. It is the fragmentary top view which looked at the center part of the sensitive sensor of further another embodiment of this invention applied to the gas sensor from upper direction. It is the IX-IX sectional view taken on the line of FIG. It is the fragmentary top view which looked at the center part of the sensitive sensor of another embodiment of this invention applied to the gas sensor from upper direction. It is the XI-XI sectional view taken on the line of FIG.

FIG. 1 is a cross-sectional view schematically showing a sensitive sensor according to an embodiment of the present invention applied to a gas sensor, and FIG. 2 is a partial plan view of a central portion of the gas sensor of FIG. 3 is an enlarged view of the central portion of the gas sensor of FIG. 1 (a cross-sectional view taken along line III-III of FIG. 2). As shown in each drawing, the gas sensor of this example includes an insulating substrate 1, a pair of thin film counter electrodes 3, 5, a pair of thin film wiring patterns 7A, 7B, and a sensitive film 9. In order to facilitate understanding, in FIG. 2, the sensitive film 9 is depicted as being transparent. In this example, the insulating substrate 1 is composed of a thin plate portion 11. The thin plate portion 11 is disposed on a cylindrical support portion 13 made of silicon single crystal. For this reason, a part of the thin plate portion 11 whose peripheral portion is supported by the support portion 13 is formed in a so-called diaphragm shape. The thin plate portion 11 is configured by laminating a SiO _0.7 N _0.7 layer 11a, a Si ₃ N ₄ layer 11b, and a SiO ₂ layer 11c from the upper side to the lower side in FIG. In this example, a heater 15 which is made of platinum and is arranged in a meandering manner is incorporated in a portion of the SiO _0.7 N _0.7 layer 11 a located above the Si ₃ N ₄ layer 11 b.

  The pair of thin film counter electrodes 3 and 5 are made of platinum, and are formed on the surface of the central portion of the thin plate portion 11 by sputtering. In this example, the pair of thin film counter electrodes 3 and 5 has a thickness dimension of 4000 mm. As shown in FIG. 2, one thin film counter electrode 3 of the pair of thin film counter electrodes 3 and 5 has an arc shape formed along a virtual annular shape (virtual circle) CA. In the present example, the contour of the sensitive film 9 and the virtual circle CA substantially coincide with each other. The other thin film counter electrode 5 of the pair of thin film counter electrodes 3 and 5 is surrounded by the one thin film counter electrode 3 and positioned at the center of the virtual circle CA. The planar contour shape of the other thin film counter electrode 5 has a circular shape that is concentric with the virtual circle CA. For this reason, the inner peripheral part 3a of one thin film counter electrode 3 and the outer peripheral part 5a of the other thin film counter electrode 5 are opposed to each other with a gap. Also, end portions 3b and 3c on the opposite side of one thin film counter electrode 3 on the side where one thin film wiring pattern 7A is located, and both side portions 7c and 7d in a direction perpendicular to the longitudinal direction of the other thin film wiring pattern 7B, Face each other at intervals. In this example, the distance L1 between the inner peripheral portion 3a of one thin film counter electrode 3 and the outer peripheral portion 5a of the other thin film counter electrode 5 is the same at any location, and the end portion 3b of one thin film counter electrode 3 is the same. , 3c and the distance L2 between the two side portions 7c, 7d of the other thin film wiring pattern 7B is the same at any location. The interval dimension L1 and the interval dimension L2 are also equal. In the center of the other thin film counter electrode 5, a hole 5b penetrating the other thin film counter electrode 5 is formed. The planar contour shape of the hole 5b also has a circular shape that is similar to the virtual circle CA. The radius R1 of the hole 5b is preferably 30 to 90% of the radius R2 of the other thin film counter electrode 5.

  The pair of thin film wiring patterns 7A and 7B are made of platinum and are formed together with the pair of thin film counter electrodes 3 and 5 by sputtering. The pair of thin film wiring patterns 7A and 7B are connected at one end to the pair of thin film counter electrodes 3 and 5 and extend toward the edge of the insulating substrate 1 respectively. On the surface in the vicinity of the edge of the pair of thin film wiring patterns 7A and 7B, extraction electrodes 21 are respectively formed (FIG. 1). The extraction electrode 21 is an electrode for extracting output to the outside, is made of gold, and is formed by sputtering.

The sensitive film 9 is made of a metal oxide semiconductor containing SnO ₂ as a main component, and an uncured sensitive film formed by dripping a sensitive liquid so as to straddle the pair of thin film counter electrodes 3 and 5 is cured by heating and formed. Has been. The sensitive film 9 has a disk shape with a raised central portion, and is formed across a pair of thin film counter electrodes 3 and 5.

  The gas sensor of this example was manufactured as follows. First, a pair of thin film counter electrodes 3 and 5 and a pair of thin film wiring patterns 7A and 7B were formed on the insulating substrate 1 by sputtering using platinum. Then, the extraction electrode 21 was formed on the pair of thin film wiring patterns 7A and 7B by sputtering using gold.

  Next, the sensitive liquid was dropped with a dispenser so as to straddle the pair of thin film counter electrodes 3 and 5 to form an uncured sensitive film. The uncured sensitive film has a disk shape with a raised center part. The uncured sensitive film was cured (baked) by heating at about 600 ° C. to form the sensitive film 9 to complete the gas sensor.

  In the gas sensor of this example, the gas concentration is measured by measuring the resistance value between the pair of thin film counter electrodes 3 and 5. In addition, according to the gas sensor of this example, since the sensitive liquid is dropped so as to straddle the pair of thin film counter electrodes 3 and 5, an uncured sensitive film is formed. A film is formed. Therefore, since one thin film counter electrode 3 has an arc shape formed along the virtual circle CA, the contour shape of the occupied portion occupied by the pair of thin film counter electrodes 3 and 5 and the contour of the occupied portion occupied by the sensitive film 9 The difference from the shape can be reduced. Therefore, the area occupied by the pair of thin film counter electrodes 3 and 5 can be reduced. In addition, since the other thin film counter electrode 5 is located at the center of the virtual circle CA surrounded by the one thin film counter electrode 3, the sensitivity located between the one thin film counter electrode 3 and the other thin film counter electrode 5. Variation in the thickness dimension of the film portion (peripheral portion) is reduced. Therefore, it is possible to suppress variation in the accuracy of the gas sensor.

  In this example, the virtual annular shape CA is a virtual circle, but it may be a virtual ellipse or a virtual polygon approximate to a circle.

  Moreover, although the example applied to the gas sensor of this invention was shown in this example, of course, this invention is applicable to other sensitive sensors, such as a humidity sensor. Further, in this example, the uncured sensitive film is cured by heating. However, the uncured sensitive film may be cured by being left to stand, for example, when used for a humidity sensor.

  Next, the results of a test examining the effect of the hole 5b formed in the other thin film counter electrode 5 will be described. First, a sensitive sensor (Example 2) having the same structure as the sensitive sensor of this example was manufactured without forming the hole 5b in the sensitive sensor (Example 1) of this example and the other thin film counter electrode 5. . Then, in an ambient temperature of 25 ° C., a voltage of 2.5 mV is applied to the heaters of the sensitive sensors of Example 1 and Example 2, and the insulative substrate of each sensitive sensor after 0.015 ms (milliseconds) after application. The upper temperature and the amount of vertical displacement of the insulating substrate were measured. FIG. 4 shows the measurement results. In FIG. 4, the horizontal axis indicates the dimension from one end in the process from one end of the sensitive sensor to the other end via the center. The position where the dimension is 1000 μm is the center of the other thin film counter electrode 5. From FIG. 4, there is no significant difference in temperature between the sensitive sensor of Example 1 (with holes) and the sensitive sensor of Example 2 (without holes). It can be seen that the sensitive sensor of Example 1 (with holes) can suppress the displacement amount at the center of the sensitive sensor by about 30% compared to the sensitive sensor of Example 2 (without holes).

FIG. 5 is a cross-sectional view schematically showing a sensitive sensor according to another embodiment of the present invention applied to a gas sensor, and FIG. 6 shows a sensitivity sensor according to another embodiment of the present invention applied to a gas sensor. FIG. 7 is a partial plan view of the central portion as viewed from above, and FIG. 7 is a sectional view taken along line VII-VII in FIG. As shown in each drawing, the gas sensor of this example includes an insulating substrate 101, a pair of thin film counter electrodes 103, 105, a pair of thin film wiring patterns 107A, 107B, and a sensitive film 109. In order to facilitate understanding, in FIG. 6, the sensitive film 109 is depicted as being transparent. In this example, the insulating base 101 is composed of a thin plate portion 111. The thin plate portion 111 is disposed on a cylindrical support portion 113 made of silicon single crystal. For this reason, a part of the thin plate part 111 whose peripheral part is supported by the support part 113 is formed in a so-called diaphragm shape. The thin plate portion 111 is configured by laminating a SiO _0.7 N _0.7 layer 111a, a Si ₃ N ₄ layer 111b, and a SiO ₂ layer 111c from the top to the bottom of FIG. In this example, a heater 115 which is made of platinum and is arranged in a meandering manner is incorporated in a portion of the SiO _0.7 N _0.7 layer 111 a located above the Si ₃ N ₄ layer 111 b.

  The pair of thin film counter electrodes 103 and 105 is made of platinum, and is formed on the surface of the central portion of the thin plate portion 111 by sputtering. In this example, the pair of thin film counter electrodes 103 and 105 has a thickness dimension of 4000 mm. As shown in FIG. 6, the pair of thin-film counter electrodes 103 and 105 each have an arc shape formed along a virtual annular shape (virtual circle) CA and facing each other. In other words, one thin film counter electrode 103 of the pair of thin film counter electrodes 103 and 105 has an arc shape formed along a virtual annular shape, and the other thin film counter electrode 105 extends along a virtual circle CA. In addition, it has an arc shape formed so as to face one thin film counter electrode 103. Between the pair of thin film counter electrodes 103 and 105, a circular thin film conductive portion 116 is formed that can be equally spaced from the pair of thin film counter electrodes 103 and 105. The planar contour shape of the thin film conductive portion 116 has a similar shape concentric with the virtual circle CA. The thin film conductive portion 116 is made of platinum and is formed by sputtering together with a pair of thin film counter electrodes 103 and 105. A plurality of concave portions 117 are formed in the pair of thin film counter electrodes 103 and 105, respectively. In this example, the plurality of recesses 117 are formed of rectangular through holes opened on the upper surface, and the pair of thin film counter electrodes 103 and 105 are formed side by side in a direction extending in an arc shape. As a result, the plurality of recesses 117 are formed in a distributed manner on the pair of thin film counter electrodes 103 and 105. In addition, dam portions 119 are formed on the pair of thin film counter electrodes 103 and 105, respectively. The dam portion 119 is made of gold of the same material as an extraction electrode described later, and is formed by sputtering. In this example, the dam portion 119 has a thickness dimension of 6000 mm. The dam portion 119 is fixed to the upper surface of the pair of thin film counter electrodes 103 and 105 and protrudes in a direction away from the insulating substrate 101, and is in a direction opposite to the direction in which the pair of thin film counter electrodes 103 and 105 face each other. The thin film is formed by a thin film continuously extending along the edges of the pair of thin film counter electrodes 103 and 105 positioned. In this example, a plurality of concave portions 117 and dam portions 119 form a resistance generating structure that provides resistance to the spread of an uncured sensitive film described later. The operation of the resistance generating structure (117, 119) will be described in detail later.

  The pair of thin film wiring patterns 107A and 107B is made of platinum, and is formed by sputtering together with the pair of thin film counter electrodes 103 and 105 and the thin film conductive portion 116. The pair of thin film wiring patterns 107 </ b> A and 107 </ b> B have ends connected to the pair of thin film counter electrodes 103 and 105 and extend toward the edge of the insulating substrate 101. On the surface in the vicinity of the edge of the pair of thin film wiring patterns 107A and 107B, extraction electrodes 121 are respectively formed (FIG. 5). The extraction electrode 121 is an electrode for extracting output to the outside, is made of gold, and is formed by sputtering.

The sensitive film 109 is made of a metal oxide semiconductor containing SnO ₂ as a main component, and an uncured sensitive film formed by dropping a sensitive liquid so as to straddle the pair of thin film counter electrodes 103 and 105 is cured by heating. Has been. The sensitive film 109 has a disk shape with a raised center part, and straddles the pair of thin film counter electrodes 103 and 105 in a state of contacting the respective dam portions 119 on the pair of thin film counter electrodes 103 and 105. Is formed.

  The gas sensor of this example was manufactured as follows. First, a pair of thin film counter electrodes 103 and 105, a pair of thin film wiring patterns 107A and 107B, and a thin film conductive portion 116 were formed on the insulating substrate 101 by sputtering using platinum. In the pair of thin film counter electrodes 103 and 105, a plurality of recesses 117 were simultaneously formed.

  Next, the extraction electrode 121 and the weir portion 119 were simultaneously formed on the pair of thin film wiring patterns 107A and 107B and the pair of thin film counter electrodes 103 and 105 by sputtering using gold.

  Next, the sensitive liquid was dropped with a dispenser so as to straddle the pair of thin film counter electrodes 103 and 105 to form an uncured sensitive film. The uncured sensitive film is prevented from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes 103 and 105 face each other by the plurality of concave portions 117 and the dam portions 119, and is in the center portion while being in contact with the dam portions 119. Becomes a raised disk shape. The uncured sensitive film was cured (baked) by heating at about 600 ° C. to form a sensitive film 109 to complete the gas sensor.

  In the gas sensor of this example, since the sensitive liquid is dropped so as to straddle the pair of thin film counter electrodes 103 and 105 to form the uncured sensitive film, the sensitive liquid spreads concentrically after the dripping and the uncured sensitive film is formed. The Therefore, the planar outline shape of the pair of thin film counter electrodes 103 and 105 has an arc shape formed so as to be opposed to each other along the virtual circle CA. The difference between the contour shape and the contour shape of the occupied portion occupied by the sensitive film 109 can be reduced. Further, in this example, since the thin film conductive portion 116 is formed in the center of the virtual circle CA (the center of the uncured sensitive film) with a space between the pair of thin film counter electrodes 103 and 105, a pair of The current flowing from one thin film counter electrode 103 to the other thin film counter electrode 105 of the thin film counter electrodes 103 and 105 is: one thin film counter electrode 103 → part of the sensitive film 109 → thin film conductive portion 116 → part of the sensitive film 109 → the other The thin film counter electrode 105 flows through the path. The part (peripheral part) of the sensitive film 109 located between the thin film counter electrodes 103 and 105 and the thin film conductive part 116 is thicker than the part (center part) of the sensitive film 109 located on the thin film conductive part 116. Small variation in dimensions. The portion of the sensitive film 109 located on the thin film conductive portion 116 does not substantially contribute to measurement. Therefore, when configured as in this example, variations in the accuracy of the sensitive sensor can be suppressed.

  Further, in the gas sensor of this example, when the sensitive liquid is dropped to form an uncured sensitive film, the sensitive liquid flowing on the pair of thin film counter electrodes 103 and 105 and the pair of thin film counter electrodes 103 are caused by the plurality of recesses 117. , 105 increases in resistance. Further, the dam portion 119 prevents the uncured sensitive film from spreading in the direction opposite to the direction in which the pair of thin film counter electrodes 103 and 105 face each other. Thus, all of the plurality of recesses 117 and dam portions 119 are resistant to the spread of the uncured sensitive film. Therefore, even if the area of the sensitive film is designed to be small, the sensitive film can be formed accurately in size and shape. As a result, when the gas sensor is mass-produced, it is possible to suppress variation in the gas sensitivity accuracy.

  FIG. 8 is a partial plan view of the center of a sensitive sensor according to still another embodiment of the present invention applied to a gas sensor, as viewed from above, and FIG. 9 is a cross-sectional view taken along the line XI-XI in FIG. The gas sensor of this example has the same structure as the gas sensor shown in FIGS. 6 and 7 except for the resistance generating structure. Therefore, the same members as those of the gas sensor shown in FIGS. 6 and 7 are given the same reference numerals as those shown in FIGS. The pair of thin film counter electrodes 203 and 205 of the gas sensor of this example form one or more protrusions (discontinuous protrusions) 219 instead of the dam portions. The discontinuous protrusion 219 is fixed to the upper surface of the pair of thin film counter electrodes 203 and 205 and protrudes in a direction away from the insulating base 201, and is positioned in a direction opposite to the direction in which the pair of thin film counter electrodes 203 and 205 are opposed to each other. The thin film counter electrodes 203 and 205 are formed by a thin film extending discontinuously along the edges. If such a discontinuous protrusion 219 is formed, when the sensitive liquid is dropped to form the uncured sensitive film, the outer periphery of the uncured sensitive film is discontinuous by the surface tension of the sensitive liquid. Will be along. Therefore, the amount of material forming the resistance generating structure can be reduced.

  FIG. 10 is a partial plan view of a central portion of a sensitive sensor according to still another embodiment of the present invention applied to a gas sensor as viewed from above, and FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. The gas sensor of this example also has the same structure as the gas sensor shown in FIGS. 6 and 7 except for the resistance generating structure. Therefore, the same members as those of the gas sensor shown in FIGS. 6 and 7 are given the same reference numerals as those shown in FIGS. A plurality of protrusions 319 are formed on the pair of thin film counter electrodes 303 and 305 of the gas sensor of this example without forming the weir portion and the plurality of recesses. The plurality of protrusions 319 are fixed to the upper surfaces of the pair of thin film counter electrodes 303 and 305, protrude in a direction away from the insulating base 301, and are dispersed on the thin film counter electrodes 303 and 305 and formed by a thin film. If a plurality of protrusions 319 are formed in this way, a pair of thin film counter electrodes 303, 305 and a plurality of protrusions 319 cause a pair of sensitive liquids to drop when a sensitive liquid is dropped to form an uncured sensitive film. The resistance between the sensitive liquid flowing on the thin film counter electrodes 303 and 305 and the pair of thin film counter electrodes 303 and 305 increases.

  In this example, an example is shown in which the present invention is applied to the gas sensor of the present invention. However, the present invention can of course be applied to other sensitive sensors such as a humidity sensor.

  Further, in this example, the uncured sensitive film is cured by heating. However, the uncured sensitive film may be cured by being left to stand, for example, when used for a humidity sensor.

  Hereinafter, the invention described in the specification of the present application will be added.

(1) an insulating substrate;
A pair of thin film counter electrodes formed on the insulating substrate and facing each other with a gap between them;
A pair of thin film wiring patterns having one end connected to the pair of thin film counter electrodes;
A sensitive film formed across the pair of counter electrodes,
A sensitive sensor formed by curing an uncured sensitive film formed by dropping a sensitive liquid so that the sensitive film straddles the pair of thin film counter electrodes,
The planar contour shape of the pair of thin film counter electrodes has an arc shape formed along a virtual annular shape and facing each other,
A thin film conductive portion is formed at the center of the virtual annular shape with a space between the pair of thin film counter electrodes,
The pair of thin film counter electrodes is resistant to spreading of the uncured sensitive film so as to prevent the uncured sensitive film from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes are opposed. A sensitive sensor characterized in that a resistance generating structure is formed.

  (2) The resistance generating structure is fixed to an upper surface of the pair of thin film counter electrodes and protrudes in a direction away from the insulating base, and is positioned in a direction opposite to a direction in which the pair of thin film counter electrodes are opposed to each other. The sensitive sensor according to (1) above, comprising one or more weir portions formed by a thin film continuously extending along the edge of the thin film counter electrode.

  (3) The resistance generating structure is fixed to an upper surface of the pair of thin film counter electrodes and protrudes in a direction away from the insulating substrate, and is positioned in a direction opposite to a direction in which the pair of thin film counter electrodes are opposed to each other. The sensitive sensor according to (1) above, comprising one or more protrusions formed by a thin film extending discontinuously along the edge of the thin film counter electrode.

  (4) The resistance generating structure is fixed to the upper surfaces of the pair of thin film counter electrodes, protrudes in a direction away from the insulating substrate, and is distributed from the plurality of protrusions formed by the thin films dispersed on the thin film counter electrode. The sensitive sensor according to (1) above, wherein

(5) An extraction electrode for output extraction is formed on a part of the pair of thin film wiring patterns,
The sensitive sensor according to (2), (3) or (4), wherein the extraction electrode and the resistance generating structure are formed of the same material.

  (6) The sensitive sensor according to (4), wherein the pair of thin film counter electrodes are made of platinum, and the extraction electrode and the resistance generating structure are made of gold.

  (7) The resistance generating structure further includes a plurality of recesses that are open on the upper surfaces of the pair of thin film counter electrodes and are formed dispersed in the thin film counter electrodes. The sensitive sensor according to (3) or (4).

(8) By sputtering, a pair of thin film counter electrodes opposed to each other with a space between each other and a pair of thin film wiring patterns each having one end connected to the pair of thin film counter electrodes are formed on an insulating substrate,
Forming an output electrode for extraction on part of the pair of thin film wiring patterns,
In the method of manufacturing a sensitive sensor, the uncured sensitive film formed by dropping the sensitive liquid so as to straddle the pair of thin film counter electrodes is cured to form a sensitive film.
Fixed to the upper surfaces of the pair of thin film counter electrodes and protruding in a direction away from the insulating substrate, so that the uncured sensitive film is prevented from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes are opposed. In addition, a resistance generating structure that becomes resistance to the spread of the uncured sensitive film is formed by sputtering simultaneously with the same material as the extraction electrode,
The resistance generating structure includes at least one dam portion formed of a thin film continuously extending along an edge of the thin film counter electrode located in a direction opposite to a direction in which the pair of thin film counter electrodes are opposed to each other; A sensitive sensor comprising one or more protrusions formed of a thin film extending discontinuously along a thin film counter electrode, or a plurality of protrusions formed of a thin film dispersed on the thin film counter electrode Manufacturing method.

(9) By sputtering, a pair of thin film counter electrodes opposed to each other with a space therebetween and a pair of thin film wiring patterns each having one end connected to the pair of thin film counter electrodes are formed on an insulating substrate,
In the method of manufacturing a sensitive sensor, the uncured sensitive film formed by dropping the sensitive liquid so as to straddle the pair of thin film counter electrodes is cured to form a sensitive film.
An opening is formed on the upper surface of the pair of thin film counter electrodes and dispersed along the thin film counter electrode, so that the uncured sensitive film is prevented from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes face each other. In addition, a method for producing a sensitive sensor is characterized in that a resistance generating structure composed of a plurality of recesses that resists the spread of the uncured sensitive film is formed simultaneously with the pair of thin film counter electrodes.

(10) By sputtering, a pair of thin film counter electrodes opposed to each other with a space therebetween and a pair of thin film wiring patterns each having one end connected to the pair of thin film counter electrodes are formed on an insulating substrate,
Forming an output electrode for extraction on part of the pair of thin film wiring patterns,
In the method of manufacturing a sensitive sensor, the uncured sensitive film formed by dropping the sensitive liquid so as to straddle the pair of thin film counter electrodes is cured to form a sensitive film.
An opening is formed on the upper surface of the pair of thin film counter electrodes and dispersed along the thin film counter electrode, so that the uncured sensitive film is prevented from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes face each other. And simultaneously forming a plurality of recesses that are resistant to the spread of the uncured sensitive film when forming the pair of thin film counter electrodes,
One or more weir portions formed by a thin film continuously extending along an edge of the thin film counter electrode positioned in a direction opposite to the direction in which the pair of thin film counter electrodes are opposed to each other, are made of the same material as the extraction electrode A method for producing a sensitive sensor, characterized by being formed simultaneously by sputtering.

  According to the present invention, since one thin film counter electrode of the pair of thin film counter electrodes has an arc shape formed so as to follow the virtual annular shape, the contour shape of the occupied portion of the pair of thin film counter electrodes, and the sensitive film Since the contour shape of the occupied portion occupied by each becomes a shape close to an annular shape, there is no great difference in size between the two. Therefore, the area occupied by the pair of thin film counter electrodes can be reduced. In addition, since the other thin film counter electrode is surrounded by one thin film counter electrode and is located at the center of the virtual annular shape, the portion of the sensitive film positioned between the one thin film counter electrode and the other thin film counter electrode ( Variation in the thickness dimension of the peripheral edge portion can be reduced. For this reason, it is possible to suppress variations in the accuracy of the sensitive sensor.

Claims (10)

An insulating substrate;
A pair of thin film counter electrodes formed on the insulating substrate and facing each other with a gap between them;
A pair of thin film wiring patterns having one end connected to the pair of thin film counter electrodes;
A sensitive film formed across the pair of counter electrodes,
A sensitive sensor formed by curing an uncured sensitive film formed by dropping a sensitive liquid so that the sensitive film straddles the pair of thin film counter electrodes,
A heater for heating the sensitive film is built in the insulating base,
One thin film counter electrode of the pair of thin film counter electrodes has an arc shape formed along a virtual annular shape,
The other thin film counter electrode of the pair of thin film counter electrodes is surrounded by the one thin film counter electrode and is located at the center of the virtual annular shape,
In the center of the other thin film counter electrode, a hole that penetrates the other thin film counter electrode is formed,
The other thin film counter electrode and the planar contour shape of the hole have an annular shape concentric with the virtual annular shape.   The dimension L1 between the one thin film counter electrode and the other thin film counter electrode of the pair of thin film counter electrodes, and the distance between the other thin film wiring pattern of the pair of thin film counter electrodes and the one thin film counter electrode. The sensitive sensor according to claim 1, wherein the dimension L <b> 2 is equal. The virtual annular shape consists of a virtual circle,
The other thin-film counter electrode and the planar contour shape of the hole have a similar shape concentric with the virtual circle,
The sensitive sensor according to claim 2, wherein a radius R1 of the hole is 30 to 90% of a radius R2 of the other thin film counter electrode.   The sensitive sensor according to claim 3, wherein the sensitive film is a gas sensitive film whose resistance value changes when gas is absorbed. An insulating substrate;
A pair of thin film counter electrodes formed on the insulating substrate and facing each other with a gap between them;
A pair of thin film wiring patterns having one end connected to the pair of thin film counter electrodes;
A sensitive film formed across the pair of counter electrodes,
A sensitive sensor formed by curing an uncured sensitive film formed by dropping a sensitive liquid so that the sensitive film straddles the pair of thin film counter electrodes,
One thin film counter electrode of the pair of thin film counter electrodes has an arc shape formed along a virtual annular shape,
The other thin film counter electrode of the pair of thin film counter electrodes is surrounded by the one thin film counter electrode and is located at the center of the virtual annular shape. An insulating substrate;
A pair of thin film counter electrodes formed on the insulating substrate and facing each other with a gap between them;
A pair of thin film wiring patterns having one end connected to the pair of thin film counter electrodes;
A sensitive film formed across the pair of counter electrodes,
A sensitive sensor formed by curing an uncured sensitive film formed by dropping a sensitive liquid so that the sensitive film straddles the pair of thin film counter electrodes,
One thin film counter electrode of the pair of thin film counter electrodes has an arc shape formed along a virtual annular shape,
The other thin film counter electrode of the pair of thin film counter electrodes has an arc shape formed so as to be along the virtual annular shape and to face the one thin film counter electrode,
A sensitive sensor, wherein a thin film conductive portion is formed at a central portion of the virtual annular shape with a space between the pair of thin film counter electrodes. The virtual annular shape is a virtual circle or a virtual ellipse,
7. The sensitive sensor according to claim 6, wherein a planar contour shape of the thin film conductive portion has a similar shape concentric with the virtual circle or virtual ellipse. A heater for heating the sensitive film is built in the insulating base,
The sensitive sensor according to claim 7, wherein the sensitive film is a gas sensitive film whose resistance value changes when gas is absorbed.   The pair of thin film counter electrodes is resistant to spreading of the uncured sensitive film so as to prevent the uncured sensitive film from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes are opposed. The sensitive sensor according to claim 8, wherein a resistance generating structure is formed. By sputtering, a pair of thin film counter electrodes facing each other with a space therebetween, and a pair of thin film wiring patterns each having one end connected to the pair of thin film counter electrodes are formed on an insulating substrate,
Forming an output electrode for extraction on part of the pair of thin film wiring patterns,
In the method of manufacturing a sensitive sensor, the uncured sensitive film formed by dropping the sensitive liquid so as to straddle the pair of thin film counter electrodes is cured to form a sensitive film.
Fixed to the upper surfaces of the pair of thin film counter electrodes and protruding in a direction away from the insulating substrate, so that the uncured sensitive film is prevented from spreading in a direction opposite to the direction in which the pair of thin film counter electrodes are opposed. In addition, a method for producing a sensitive sensor is characterized in that a resistance generating structure that is resistant to the spread of the uncured sensitive film is formed simultaneously by sputtering with the same material as the extraction electrode.

Images