JPS5896722A - Capacity type moisture sensor and method of producing same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitive humidity sensor and a method for manufacturing the same. An extremely high-performance humidity sensor and its g! It concerns law reform.

In general, an electric hygrometer is understood as a transducer that displays changes in electrical characteristics due to changes in humidity conditions as relative humidity, and its water replenishment principle is one that makes full use of changes in electrical resistance, and one that uses static electricity. There are two types: those that measure changes in capacitance I; and those that measure changes in capacitance I. Of these, the latter, the Seiden Yongfu style,
In other words, it is a type of humidity sensor that determines humidity by measuring the change in capacitance I when the moisture-sensing part absorbs moisture. However, it is said that there is a problem in practical use because the measurement sensitivity is poor.
Humidity sensors using dielectrics and organic polymer films that function as
No. 2 and US Pat. No. 33!02t1.

By the way, in general, when a dielectric material made of an organic polymer film is used as a moisture-sensitive layer, this dielectric material has excellent responsiveness to one-dimensional music and has good repeatability. Since the relationship appears extremely linear, it has advantages such as improved measurement accuracy. On the other hand, however, the organic polymer film dielectric has the disadvantage that if it is exposed to excessively dry conditions and high humidity (11) for a long period of time, it will peel off from the substrate and its moisture sensitive properties will deteriorate.

In addition, since organic polymer membranes are easily attacked by organic solvents (e.g. acetone),
It has been pointed out that in an atmosphere where a large amount of lubricant vapor is present, it is adversely affected and cannot be used.

Therefore, there is a strong demand in the industry for the practical application of a humidity sensor with excellent mechanical strength, which can be suitably used in adverse environments such as high temperature conditions and organic solvent atmospheres. For example, Japanese Patent Application Laid-Open No. 3.2-1
No. 817 [Metal Oxide Film Moisture Sensing Element] and JP-A No. 3-J
rij → [Wetness detection element j using an anodic oxide film of aluminum for If, etc. have been proposed. In both of these methods, a conductive porous gold (4) oxide film is formed on the substrate itself, such as an aluminum plate, by electrolysis or other means, but measurement errors are likely to occur due to the roughness of the element surface. However, the mechanical strength of the metal oxide film itself was not as high as that of light, and thus did not meet the above requirements.

Therefore, in order to solve the above-mentioned drawbacks, the inventors have carried out various prototype research on the bond, the substrate itself [oxidation, etc.] Instead of forming a film by solution, a film of a metal compound (e.g. gold oxide, gold@nitride) is deposited on an insulating substrate that is not compatible with oxidation, such as glass, and the vapor of the corresponding metal is applied in a high-frequency electric field. Oxygen
If fc is formed by introducing nitrogen or ammonia gas and ion blating, the resulting metal compound film will have extremely high strength. Since the surface is smooth and dense, it was found that responsiveness, repeatability, IL, and measurement accuracy were improved, and a patent application was filed.

However, after that, it is preferable to perform ion blating by sputtering the corresponding gold with an ion gun in a high-frequency electric field while introducing a mixed gas of oxygen and argon, 1 ammonia gas, or a mixed gas of nitrogen and hydrogen under a high vacuum. Furthermore, the present invention was completed based on the discovery that if the surface of the metal compound film is roughened by mechanical treatment, such as plasma etching, the responsiveness can be significantly improved.

Therefore, the general object of the present invention is to have excellent mechanical strength;
To provide a 6-meter humidity sensor that exhibits poor performance even in harsh environments such as high temperature conditions and organic solvent atmospheres. .

In order to achieve this object, the present invention arranges electrodes facing each other on a non-conductive substrate, independently forms a moisture-active metal compound film on the electrodes, and roughens the metal compound film by mechanical treatment. A surface, and a moisture-permeable gold peel on the rough surface is formed into a shape Ijy, r stone.

Ion plating with an ion gun in a high-frequency zone is preferably used as a method for forming the metal compound*J1 on a substrate, and one sample of the obtained metal compound is subjected to plasma etching and C phase opening using the same equipment. be done. Therefore, in the method for manufacturing a humidity sensor according to the present invention, a non-conductive substrate is supported on a high-voltage electrode in a vacuum forming chamber, and a high pressure metal seal is applied to the substrate, thereby evacuating all infertile gases in the vacuum forming chamber. After introducing a predetermined gas from the outside and forming a high frequency 11T field in the vacuum forming chamber, one metal plate or metal compound placed in the vacuum forming chamber is sputtered with ions from an ion gun. After generating gold ions or all-class compound ions, converting the metal ions into metal compound ions by the introduced gas, and forming a sample of the metal compound film independently on the non-conductive substrate and the electrode, the subsequent canning is performed. The present invention is characterized in that the application of the high pressure is increased to roughen the entire surface of the metal compound film 11 by plasma etching, and a moisture-permeable metal film is entirely formed on the rough surface.

Next, the customer layer type humidity sensor and its manufacturing method according to the present invention will be described in detail below with reference to preferred embodiments and all the accompanying drawings.

1 and 2 show an embodiment of each wrinkle type humidity sensor according to the present invention, and as shown in FIG. The lower electrodes are formed oppositely to a thickness of about 1/μ by means of vapor deposition, photoetching, etc. In this case, the lower electrodes are 1@-shaped and arranged in a pattern such that the comb teeth mesh without touching each other. It is preferable to do so. Note that chemically inert gold, palladium, or the like is preferably used as a material for the lower electrodes.In this way, the lower electrodes are formed on the substrate 10 on which the electrodes /2 and /2 are formed. As described later, an ion blating method using a high frequency power source is carried out to coat a moisture-active metal compound film (for example, a metal oxide film or a metal nitride film).
Shape 1 is cut independently to the substrate with a thickness of ~2μ.

This surface is mechanically roughened, for example by plasma etching, to form a rough surface/6 with a thickness of about 10.degree. Furthermore, a moisture-permeable and chemically stable metal such as synthetic leather or palladium film is vapor-deposited on top of the obtained metal compound film/≠ rough surface/ to a thickness of 200−λjO^. Let it be the upper electrode it. As a result, a humidity sensor 1 (sensor) having extremely excellent mechanical strength and extremely good responsiveness can be obtained.

Next, the lower electrode/,2. 1 Regarding the method of forming the metal compound film /≠ and the rough surface 16 on the substrate 10 with /2 formed E7
Be happy. Figure 3 (1) shows an outline of an apparatus for carrying out this method, in which a negative electrode 22, a coil 2≠, and a metal compound plate are placed in a vacuum forming chamber 2θ that can be airtightly isolated from the outside world. IF electric book and ion gun, 2t
are arranged as shown. Front dpi IE negative arousal pole 22
,．． 26 (fcId-0,0j ~/kV 11th flow'
1 so that the city pressure is applied, and the coil 2 is connected to an external high frequency source 30. 1E peep pole 2
At the bottom of coil 2≠, connect it with the ion gun by about 2 to 3
The IF electrodes 2 are arranged at a distance of t-n+ at an angle of 0 degrees, and the IF electrodes 2 are inclined at an angle of about urH5 with respect to the horizontal direction.
A current of jmN to 10 mA is supplied at the voltage of V.

In addition, the tube body 3 is led out from the itl record forming chamber 1O, and connected to the vacuum pump 3g through 36 cells, and the tube body ≠O is similarly led out from the vacuum formation chamber 20. Valve body 2
It is connected to a gas source (not shown), which will be described later.

During operation, it is applied to the lower surface of one electrode in the empty forming chamber 2θ, the lower electrode/2. After the substrate 10f on which the substrate 2 is formed is fixed horizontally, and an aluminum plate, for example, is fixed to the anode 2t, the vacuum forming chamber 20 is hermetically closed. Next, the vacuum pump 311fJi.

to remove impurity gas in the vacuum forming chamber 2.0, and when the degree of vacuum reaches 10 to 10 tnrr, the valve≠2.
was opened, and a mixed gas in the ratio of oxygen (d) and argon (l) was introduced into the chamber 20, or a mixed gas in the ratio of -r ammonia, moss, nitrogen, and hydrogen (l) was introduced into the chamber 20. 3x
10 torr, the negative electrode, 2.2;
Apply a DC voltage of 10 to 100V. In history, coil 2
'tt has 200WI and 300~■/j, J
j-MI (connect the high frequency power supply of z, and also connect the ion gun 2
1 is activated to sputter the aluminum plate attached to the positive electrode 2B, and the generated aluminum ions are sent to the coil 2I.
Aluminum oxide is concentrated on the substrate IO and the lower electrode /2, to which a voltage is applied by the electrode 22, and reacts with the mixed gas to form aluminum oxide on the substrate 10 and the lower electrode /2. Or form a film of aluminum nitride.

The thickness of the aluminum compound film becomes l to λμ by ion blating for ti-o-J'o. Ion irradiation from an ion gun to an aluminum plate attached to the positive electrode, positive @, 1! The film thickness can be controlled by adjusting the voltage applied to the poles. Next, the electrode 22
．． By increasing the voltage applied to 26 to Ot~/kV and continuing the ion grating operation, plasma etching is performed on the previously formed ion brating skin, and after about 20 minutes, 100~tooQ is etched. The thickness makes me laugh. The gs diagram and the second figure are scanning electron micrographs (X10,000) showing cross-sectional photographs before and after surface roughening. After forming the so-called metal compound film l≠ and rough surface /2 in this way, the above-mentioned moisture-permeable metal upper electrode /I, for example, a full film or a palladium film, is deposited to form a layer of approximately 200-λ ! O^
Form a layer of skin with a thickness of . In this way, a humidity sensor according to the present invention can be obtained.

By performing this ion blating in a high frequency electric field, the adhesion strength of the aluminum oxide formed on the substrate IO and the lower electrode 12 is extremely high, and aluminum oxide has excellent heat resistance, acid resistance, and solvent resistance. Therefore, it can withstand use in harsh environments such as factories with rope temperature conditions and a lot of acid and organic solvent vapor. In the previous example, aluminum was attached to the positive electrode 2B when gold oxide such as aluminum oxide was formed by ion blasting, but the oxygen/argon mixed gas introduced into the vacuum forming chamber was When ammonia gas or a mixed gas of nitrogen and hydrogen is introduced into a nitride film, a metal nitride film is formed on the substrate, and like metal oxides, this metal perride also exhibits properties suitable for use as a humidity sensor. It is.

Furthermore, instead of aluminum, magnesium may be used as the material sample. Furthermore, the object to be attached to the IE electrode is not a metal plate, but a metal r*r metal or metal nitride plate, and an ion gun of metal oxide or metal nitride is used to attach the metal oxide or metal nitride ion tube to the substrate IO and the lower part. It is also possible to form a film of gold@oxide or metal/podide on the 11-pole lλ.

According to the capacitive humidity sensor according to the present invention, the response to humidity changes is extremely quick, as shown in FIG. In other words, Fig. 1 shows the humidity sensor's % characteristics, and compares the storage humidity Ftt using an FC Taniwa hygrometer using an aluminum oxide film that does not roughen the surface of the FC Taniwa hygrometer with an aluminum oxide film that uses a roughened aluminum oxide film. Relative humidity / 7j%, rs% when placed in a constant humidity tank with humidity of 1 to 3j% and reaching an equilibrium state.

This is a plot of the relationship between the RIL QC meter's readings and time after placing it in each humidity chamber in section 7j. Song #5! In the case of a moisture meter with aluminum oxide film, the curve (indicated by -■-) has a roughened surface and r (rough aluminum oxide film). The case of a 1-capacity hygrometer using
．． In all cases of J% January 1° 71 ratio, approximately equilibrium 1 (reaches) in about <10 seconds, but the case where the surface does not become rough is "4" as shown in the figure.
It takes about 5 minutes. This clearly shows the improvement in response due to surface roughening. The response characteristics of a conventional hygrometer with aluminum oxide formed on an aluminum plate were measured in the same way as a commercially available hygrometer. The improvement in response due to surface roughening seems to be related to the formation of a flaky crystal structure on the rough surface, and it is easier to form columnar crystals in a nitride film than in an oxide film.

According to the manufacturing method of the present invention, the metal tung compound coating (this includes both metal nitride coatings and metal nitride coatings) is extremely strongly formed on the substrate, so the mechanical strength is low. It is sufficiently durable and can withstand 6'i severe use. In particular, since the dielectric body is made of a Φ polymer film and a rc<gold compound film, it can be used for a long time without impairing the characteristics of the moisture sensitive part even in an atmosphere filled with organic solvent vapor. It has the advantage of being used sparingly and hardly changing over time.

Additionally, the heat resistance has been significantly improved, making it easier to solder the electrodes, and when the moisture sensing part absorbs too much moisture, the sensor itself can be heated to dry it.

1μF1 Although the container type humidity sensor and the manufacturing method thereof according to the present invention have been described by citing preferred embodiments, the present invention is not limited to these embodiments, and many improvements can be made within the spirit of the invention. Changes can be made.

[Brief explanation of drawings]

FIG. 1 is a plan view of a capacitive humidity sensor according to the present invention, and FIG.
The figure shows the capacitive humidity sensor according to the present invention shown in FIG.
A top view of U-line 1, FIG. 3 is a schematic diagram of the equipment for carrying out the manufacturing method according to the present invention, and FIG. 3 is a diagram showing the roughened metal compound according to the present invention. Response characteristics of a capacitive humidity sensor (indicated by a curve -・-) used in the history of Kankei 1 and a capacitive humidity sensor using a metal compound*J film that does not roughen the surface (indicated by a curve -■-) Figures 45 and 45 are scanning electron micrographs showing cross sections of unroughened and roughened aluminum oxide films. 10...Substrate /λ...Lower electrode/≠...
・Kinne compound 1/A... Rough surface/r... Upper electrode 20... Vacuum forming chamber 22... Negative electrode
, 24t°°° coil, 2J...positive electrode
Jr...°Ion gun 30...High frequency power supply 32
・Pion gun power supply 3≠...Pipe body 3t...
Valve body 3g...Vacuum pump 3...Pipe body≠2
... Valve body Fl (3, I FIG, 2 FIG4 -96- FIG, 5

Claims (8)

[Claims] (1) Electrodes are arranged to face each other on a non-conductive substrate, a moisture-active metal compound film is independently formed on the electrodes, this metal compound is made into a rough surface by mechanical treatment, and the surface of the rough surface is A capacitive humidity sensor formed by forming a moisture-permeable metal skin g. (2) The hydraulic humidity sensor according to claim 1, wherein the non-conductive substrate is a sapphire plate or a glass plate. (3) The capacitive humidity sensor according to claim 1 or 2, wherein the metal compound plate is a gold happy oxide model or a metal nitride film. (4) The wet-irradiation process according to any one of items 7 to 3, wherein the mechanical treatment is plasma etching and the range of aluminum % tolerance. (5) The adhesive type humidity sensor according to any one of claims 1 to q, wherein the electrodes are formed in a comb shape and are arranged to face each other so that the comb teeth mesh with each other without contacting each other. (6) N4W1. are placed facing each other and supported on high-voltage electrodes in a vacuum forming chamber, and a high voltage is applied.
Impurity gases in the vacuum forming chamber are removed by creating a high vacuum, a predetermined gas is introduced from the outside, a high frequency electric field is formed in the vacuum forming chamber, and then a metal plate or metal compound plate is placed in the vacuum forming chamber. is sputtered with ions from an ion gun to generate metal ions or metal compound ions, and the metal ions are converted into metal compound ions by the introduced gas, thereby forming an independent metal compound film on the non-conductive substrate and the electrode. After the formation, the application of the high voltage is subsequently increased to plasma-etch the metal compound film HA to phase open it, thereby forming a moisture-permeable metal film entirely on the rough surface H. Fukushiki Humidity 1 (Sensor manufacturing method. (7) The metal compound plate is aluminum or magnesium, and the metal compound plate is an aluminum casing or magnesium oxide or nitride.
81! Desire law. (8) The gas introduced into the vacuum forming chamber is a mixed gas of oxygen and argon, ammonia gas, or a mixed gas of nitrogen and hydrogen.
Manufacturing method described in section.