JPH10163005A - Metal oxide film resistor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method oxide film resistor having a wide range of resistance and small temp. coefficient by forming a first metal oxide protective film at least on an insulative substrate, metal oxide resistance film on the protective film, and second metal oxide protective film on the resistance film. SOLUTION: On an insulative substrate 1, a first metal oxide protective film 2 is formed which is composed of crystal grains grown in a columnal shape and oriented in a specified crystal plane. On the protective film 2, a metal oxide resistance film 3 is formed which is composed of crystal grains grown in a columnal shape. On the resistance film 3, a second metal oxide protective film 4 is formed which is composed of crystal grains grown in a columnal shape. It suffices so long as the protective films 2, 4 are made of a metal oxide film material having the same crystal structure as that of the resistance film 3. The resistance film 3 is pref. one contg. Sn oxide, In oxide and Zn oxide as main components, and the formed protective film 2 is 150-500nm thick.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal oxide film resistor which is widely used for forming circuits of various electric devices, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Metal oxide film resistors are usually rod-shaped insulating substrates such as mullite or alumina, and tin oxide or antimony-added tin oxide (ATO) formed on the surface thereof.
A metal cap terminal that is pressed into both ends of the substrate and contacts the resistance film, a lead wire welded to the cap terminal, and a protective film that covers the surface of the resistance film. I have. When the metal oxide resistance film material has a single phase of tin oxide, the specific resistance is large, and the temperature coefficient of resistance (TCR) is a negatively large value. For this reason, generally, as a metal oxide film material, the specific resistance is small,
ATO having a positive or close to 0 TCR has been put to practical use.

In order to produce this kind of metal oxide film,
Generally, a chemical film forming method such as a spray method or a chemical vapor deposition method (CVD) is used. In these methods, 600-
In a furnace heated to 800 ° C., a vapor of an aqueous solution or an organic solvent solution containing stannic chloride and antimony trichloride is sprayed onto a rod-shaped mullite-alumina base material, so that ATO is formed on the surface of the base material. Form a film. At this time, the thickness of the obtained ATO film is 400 to 1000 nm, and the microstructure of the film is such that a region of 150 nm from the base material is composed of granular polycrystalline grains, and a region of 150 nm or more grows to have a columnar crystal. It is a grain. Next, a metal cap terminal is pressed into both ends of the base material, and a part of the ATO film is trimmed with a diamond cutter or a laser while rotating the base material to a desired resistance value. After welding, by forming a resin protective film,
The metal oxide film resistor is completed. The completed resistance value of the metal oxide film resistor obtained in this manner varies depending on the thickness of the ATO film and the number of trimming turns, if the size of the base material is constant, but is generally from 10Ω to 100 kΩ.

[0004]

According to the above-described resistance adjusting method, in order to obtain a metal oxide film resistor having a completed resistance value of 100 kΩ or more, the thickness of the ATO film must be reduced or the ATO film must be thinned. A method of narrowing the trimming interval of the image is considered. However, the specific resistance of the ATO film is about 1 ×
Since it is 10 ⁻³ to 1 × 10 ⁻² Ω · cm, the film thickness must be considerably reduced in order to increase the resistance value. When the film thickness is reduced, the strain of the film itself and the ratio of the depletion layer on the film surface to the entire film increase, so that it is difficult to obtain a product of constant quality. In addition, since the crystallinity of the film itself is low, there is a problem that the TCR tends to be a large negative value. Furthermore, since the initial resistance value of the ATO film is low, if the final resistance value is set to 100 kΩ or more, the number of turns of the trimming by the laser increases, and the trimming takes a very long time and the trimming interval becomes too narrow. However, there is also a problem that the trimming cannot be performed physically.

[0005] As described above, when the film thickness is reduced or the trimming interval is reduced, the cross-sectional area of the electric conduction path decreases and the contact area with the outside increases. Furthermore, since the crystallinity of the grains constituting the resistive film itself is low and there are many grain boundaries, the resistance value of the film itself changes due to the effects of moisture and alkali ions in the insulating base material due to electrical stress and humidity. Therefore, it was difficult to obtain a metal oxide film resistor having high reliability. The present invention solves the above-mentioned problems, and has a completed resistance value of 100 kΩ or more, a small TCR,
An object of the present invention is to provide a highly reliable metal oxide film resistor.

[0006]

According to the present invention, there is provided a metal oxide film resistor comprising at least an insulating base material, and a first crystal grain which is oriented on a predetermined crystal plane on the base material and grown in a columnar shape. A metal oxide protective film, a metal oxide resistive film composed of columnar crystal grains grown on the protective film, and a second metal oxide protective film composed of columnar crystal grains grown on the resistive film. Have. Here, it is preferable that the film thickness of the first metal oxide protective film is equal to or larger than the film thickness of the second metal oxide protective film. Also, the first
The average thickness of the metal oxide protective film is 150 to 500 n.
m is preferable. Further, the present invention provides a metal oxide resistance film comprising at least an insulating base material, and a columnar crystal grain having a crystal composition distribution within a particle, wherein the crystal grows while being oriented in a certain crystal plane on the base material. A metal oxide film resistor comprising: The method for producing a metal oxide film resistor according to the present invention includes a step of forming a first metal oxide protective film composed of crystal grains which are oriented in a certain crystal plane and grown in a columnar shape on an insulating base material, Forming a metal oxide resistance film made of columnar crystal grains grown on the protective film, forming a second metal oxide protective film made of columnar crystal grains grown on the resistance film; And annealing at a temperature equal to or higher than the film forming temperature of the resistance film.

[0007]

FIG. 1 shows a metal oxide film resistor according to one embodiment of the present invention. An insulating substrate 1, a first metal oxide protective film 2 composed of crystal grains oriented in a certain crystal plane formed on the substrate 1 and grown in a columnar shape, and a columnar crystal grown on the protective film 2. A metal oxide resistance film 3 composed of crystal grains, a second metal oxide protective film 4 composed of columnar crystal grains grown on the resistance film 3, and a metal cap terminal 6 press-fitted at both ends of the substrate 1. And 7, lead wires 8 and 9 welded to the terminals, and a protective film 10 formed on the surface of the resistor.

Here, the substrate 1 only needs to have an insulating property at least on its surface, and is preferably made of porcelain such as mullite, alumina, cordierite, forsterite, and steatite. The protective film 2 suppresses diffusion of alkali ions into the resistance film 3, and the protective film 4 suppresses deterioration of the resistance film 3 due to electrochemical reaction due to moisture. Each of the protective films 2 and 4 has lower electric conductivity than the resistance film 3 and
Any metal oxide film material having the same crystal structure as described above may be used. On the other hand, the resistance film 3 preferably has a high electric conductivity and a high carrier concentration, and preferably includes tin oxide, indium oxide, and zinc oxide as main components.

When the resistance film 3 is mainly composed of tin oxide, the protective films 2 and 4 are preferably made of either tin oxide or titanium oxide (rutile structure) or a solid solution thereof, and the resistance film 3 mainly contains indium oxide. When it is used as a component, indium oxide is preferable, and when the resistance film 3 mainly contains zinc oxide, either zinc oxide or cadmium oxide or a solid solution thereof is preferable. Further, the specific resistance of the protective films 2, 4 and the resistance film 3 depends on the additive added to the main component. Tin oxide, indium oxide, zinc oxide, etc. may be used for the protective films 2 and 4 in a single phase of 10 ^-1.
It can be used at about 10 ⁻² Ω · cm. In the case of tin oxide, the same tetravalent titanium oxide or silicon oxide as tin is used. In the case of indium oxide, the same trivalent titanium as indium is used.
In the case of zinc oxide, a low-resistivity material to which a bivalent alkaline earth oxide or the like same as zinc is added can be used. In the case of tin oxide, the resistance film 3 is made of pentavalent antimony oxide, phosphorus oxide, arsenic oxide or the like having one valence larger than tin. In the case of zinc oxide, an appropriate amount of trivalent aluminum oxide, indium oxide, gallium oxide, or the like is added. It is preferable to use a material that is high and has a TCR of positive or close to zero.

FIG. 2 shows a metal oxide film resistor according to another embodiment of the present invention. An insulating base material 1, a metal oxide resistance film 5 formed on the base material 1, metal cap terminals 6 and 7 pressed into both ends of the base material, lead wires 8 and 9 welded to the terminals, And a protective film 10 formed on the surface of the resistor. Here, the resistive film 5 is formed of columnar crystal grains having a crystal composition oriented in a predetermined crystal plane and having a chemical composition distribution in the grains, and the crystal grains are formed of a portion having high electric conductivity and a portion having a higher electric conductivity. It consists of a part with low electrical conductivity. The resistance film preferably has tin oxide, indium oxide, or zinc oxide as a main component. When tin oxide is used as the main component, pentavalent antimony oxide, phosphorus oxide, arsenic oxide, or the like having a valence of one greater than tin is used for the portion having high electric conductivity. In the case of indium oxide, For example, tetravalent tin oxide, titanium oxide, zirconium oxide, and the like having a valence of one greater than indium, and in the case of zinc oxide, trivalent aluminum oxide, indium oxide, and gallium oxide having a valence of one greater than zinc. Are preferably added, each having a high specific resistance and a TCR of positive or close to 0. In addition, tin oxide, indium oxide, zinc oxide, etc. can be used in a single phase at a low electrical conductivity of about 10 ⁻¹ to 10 ⁻² Ω · cm. In the case of tin oxide, the same tetravalent titanium oxide or silicon oxide as tin, in the case of indium oxide, the same trivalent aluminum oxide or rare earth oxide as indium, or in the case of zinc oxide Also, a material having a low specific resistance to which the same divalent alkaline earth oxide as zinc is added can be used.

Next, the metal oxide film manufacturing apparatus shown in FIG. 3 will be described. Quartz reaction tube 11 containing substrate 1
Is fixed by a packing 13 in a furnace core tube 12 also made of quartz. Furnace core tube 1 inserted into electric furnace 14
2 is driven by a driving device (not shown) to
It is adapted to be rotated at an appropriate rotation speed in the interior. The raw material supply device 16 containing the metal oxide film forming composition 15 is connected to a gas supply device 17 for supplying a carrier gas by a pipe 18 and is connected to the reaction tube 11 by a pipe 19. The reaction tube 11
An exhaust device 21 is connected to the other end by a pipe 20.

In order to form a metal oxide film on the surface of a substrate using this apparatus, first, the substrate is placed in a reaction tube 11 and set as shown in the drawing, and the substrate is heated by an electric furnace 14.
While maintaining the temperature at which the composition for forming a metal oxide film is thermally decomposed or higher, the reaction tube 11 is rotated. In this state, a carrier gas is sent from the gas supply device 17 to the raw material supply device 16 through the pipe 18, and the gas or mist of the composition for forming a metal oxide film is supplied to the reaction tube 11 through the pipe 19. The gas or mist supplied to the reaction tube 11 is decomposed by contacting the base material to form a metal oxide film on the surface of the base material. Then, the undecomposed metal oxide film forming composition is sucked by the gas exhaust device 21, cooled, and collected. In addition, as the carrier gas supplied from the gas supply device 17, air, oxygen, or an inert gas such as nitrogen or argon is used. The supply amount of the gas or mist can be controlled by the flow rate of the carrier gas. Further, the supply amount of the gas or mist can be controlled by heating the raw material supply device 16 or applying ultrasonic waves to the raw material supply device. The rotation of the reaction tube 11 is for uniformly forming the metal oxide film on the substrate, and mechanical vibration may be applied instead of rotating the reaction tube 11. Further, there is no particular need to rotate the furnace core tube 12, and in this embodiment, the reaction tube 11 is not required.
Is fixed to the furnace core tube 12 in order to stabilize the rotation.

Embodiment 1 In this embodiment, a resistor having the structure shown in FIG. 1 was manufactured. First, a composition for forming the metal oxide protective film 2, a composition for forming the metal oxide resistance film 3, and a composition for forming the metal oxide protective film 4 were prepared as follows. In a 200 ml Erlenmeyer flask, 5 g of stannic chloride (SnCl ₄ .5H ₂ O) and M (= Si) expressed as 100 × M / (Sn + M)% in terms of the number of moles of metal M ) And silicon tetraethoxide (Si (OCH ₂ CH ₃ ) ₄ ) corresponding to 10 mol% (hereinafter simply referred to as mol%), and weighed 75 ml.
Was added and dissolved to prepare a composition for forming the protective film 2. Also, 5 g of stannic chloride and antimony trichloride (SbCl ₃ ) corresponding to 3 mol% of Sb were weighed into a 200 ml Erlenmeyer flask, and 68 ml of the mixture was weighed.
Was added and dissolved in 8 ml of concentrated hydrochloric acid to prepare a composition for forming the resistance film 3. Further, 5 g of stannic chloride (SnCl ₄ .5H ₂ O) was weighed, and dissolved by adding 68 ml of methanol and 8 ml of concentrated hydrochloric acid to prepare a composition for forming the protective film 4.

Using the production apparatus shown in FIG. 3, an alumina content of 92% was used.
The protective film 2, the resistance film 3, and the protective film 4 were sequentially formed on the surface of the cylindrical substrate 1 (outer diameter 2 mm, length 10 mm, surface roughness Ra = 0.3 μm). That is, the substrate 1 was placed in the reaction tube 11 and the composition for forming the film 2 was placed in the raw material supply device 16. Air was used as the carrier gas, the gas flow rate was 1 liter / min, and the heating temperature of the substrate 1 was 700 ° C. Note that the heating temperature of the substrate 1 may be lower than the deformation temperature of the substrate 1 or the melting point of the coating 2.
The higher the heating temperature, the better the film quality of the obtained film 2, and the temperature is preferably 400 to 900 ° C. Reaction tube 1 at 700 ° C
1 was held for 30 minutes, and then the composition for forming a coating 2 was placed in a reaction tube 11 at a rate of 0.2 g / min for 10 to 10 minutes.
After feeding for 20 minutes to form the film 2, the film 2 was kept at 700 ° C. for 10 minutes. The film thickness of the film 2 formed in this manner is usually several tens to several thousand nm, but in this embodiment, it is about 1 nm.
It was 00 to 200 nm.

Next, similarly, the substrate 1 on which the film 2 was formed was placed in a reaction tube, and the composition for forming the film 3 was placed in a raw material feeder 16. Air was used as the carrier gas, the gas flow rate was 1 liter / min, and the heating temperature of the substrate 1 was 700 ° C. The heating temperature of the substrate 1 is
It suffices that the temperature be equal to or lower than the deformation temperature of the base material 1 or the melting point of the film 2 and the film 3. The higher the heating temperature, the better the film quality of the obtained film 3, and preferably 400 to 900 ° C. 70
The substrate 1 in the reaction tube 11 was held at 0 ° C. for 30 minutes, and then 1 g of the composition for forming the coating 3 was placed in the reaction tube 11 for 5 minutes.
After sending the resistive film 3 for a further 70 minutes.
Hold at 0 ° C. for 10 minutes. The film thickness of the resistance film 3 thus formed is usually several tens to several thousand nm, but in this embodiment, it was about 150 nm.

In the same manner, the substrate 1 on which the resistance film 3 was formed was placed in a reaction tube 11 and the composition for forming the film 4 was placed in a raw material supply device 16. Air was used as the carrier gas, the gas flow rate was 1 liter / min, and the heating temperature of the substrate 1 was 700 ° C. The heating temperature of the substrate 1 may be lower than the deformation temperature of the substrate 1 or the melting point of the film 3 and the film 4, and the higher the heating temperature, the better the film quality of the obtained film 4 is. ~ 900 ° C is preferred. The substrate 1 in the reaction tube 11 was held at 700 ° C. for 30 minutes, and then the composition for forming a film 4 was fed into the reaction tube 11 at a rate of 0.1 g / min for 10 to 20 minutes to form a film 4. After that, the temperature was further maintained at 700 ° C. for 10 minutes. The film thickness of the film 4 thus formed is usually several tens to several thousand n
m, but in this example, it was about 100 to 200 nm.

The tin-plated stainless steel cap terminals 6 and 7 are press-fitted into both ends of the substrate 1 on which the coatings 2, 3 and 4 are formed, and the diamond cutter 1
After trimming for two turns, the cap terminal 6,
7, copper-plated lead wires 8 and 9 plated with tin were welded. Note that the cap terminals 8 and 9 only need to be ohmically joined to the film 4, and the lead wires 8 and 9 only need to be ohmically joined to the cap terminals 6 and 7. Finally, a thermosetting resin paste was applied to the surface of the film 4, dried, and heated at 150 ° C. for 10 minutes to form an insulating protective film 10. Thus, a metal oxide film resistor was obtained. The protective film 10 may have insulation and moisture resistance, and may be made of a material containing only a resin or an inorganic filler, and may be cured using light such as visible light or ultraviolet light in addition to heat. Good.

The thicknesses of the protective films 2 and 4, the initial resistance value (value before trimming), the completed resistance value (value after trimming), the TCR of the obtained metal oxide film resistor, and the TCR after the moisture resistance test. Table 1 shows the rate of change of the resistance value with respect to the value before the test. The TCR is a value at 25 ° C. to 125 ° C., and the moisture resistance test is a test in which the sample is exposed to an atmosphere of 60 ° C. and 95% RH for 100 hours.

[0019]

[Table 1]

An insulating base material and a highly crystalline metal oxide resistive film composed of crystal-grown columnar crystal grains are mainly used as a resistor, and two layers are formed above and below the resistive film. By forming a highly crystalline metal oxide protective film consisting of columnar crystal grains, the diffusion of alkali ions, which is a factor in lowering the reliability due to thinning for higher resistance, and the electrochemical reaction with moisture The deterioration of the resistance film due to the reaction can be suppressed.

Example 2 A substrate 1 was prepared in the same manner as in Example 1.
After forming a protective film 2, a resistive film 3, and a protective film 4 on the surface of, an annealing treatment was performed at 800 ° C. for 10 minutes in an air atmosphere. Otherwise, a metal film resistor was manufactured under the same conditions as in Example 1. Table 2 shows each characteristic of the obtained metal oxide film resistor.

[0022]

[Table 2]

A first metal oxide protective film is formed on the insulating substrate, the first metal oxide protective film being composed of crystal grains which are oriented in a predetermined crystal plane and grown in a columnar shape, and a crystal is grown on the protective film. Forming a metal oxide resistive film made of columnar crystal grains, forming a second metal oxide protective film consisting of columnar crystal grains grown on the resistive film, and then forming the resistive film. By annealing at a temperature or higher, the crystallinity of the resistive film and the protective film can be increased, the TCR as a resistor becomes positive or close to 0, and a decrease in reliability due to high resistance can be suppressed. A highly reliable metal oxide film resistor having a small TCR and a high resistance can be obtained.

Example 3 In this example, a metal oxide film resistor having the structure shown in FIG. 2 was manufactured using two types of compositions for forming a resistance film. In a 200 ml Erlenmeyer flask, 5 g of stannic chloride (SnCl ₄ .5H ₂ O) and T
i corresponds to 10 mol% of titanium tetrachloride (TiC
l ₄ ) was weighed and dissolved by adding 68 ml of methanol and 8 ml of concentrated hydrochloric acid to prepare a composition A for forming a resistive film. In a 200 ml Erlenmeyer flask, 5 g of stannic chloride and antimony trichloride (SbCl ₃ ) corresponding to 9 mol% of Sb were weighed and dissolved by adding 68 ml of methanol and 8 ml of concentrated hydrochloric acid. Various types of compositions B for forming a resistive film were prepared.

Using the manufacturing apparatus shown in FIG. 3, the base material 1 was placed in a reaction tube, and the composition A for forming a resistive film was placed in a raw material supplier 16. Air was used as the carrier gas, the gas flow rate was 1 liter / min, and the heating temperature of the substrate 1 was 800 ° C. The heating temperature of the substrate 1 may be lower than the deformation temperature of the substrate 1 or the melting point of the film 5, and the higher the heating temperature is, the better the film quality (crystallinity) of the obtained film 5 is.
0-900 degreeC is preferable. The substrate 1 in the reaction tube 11 is
After holding at 0 ° C. for 30 minutes, 3 g of the composition A for forming a resistive film was sent into the reaction tube 11 over 15 minutes. continue,
While the temperature was lowered from 800 ° C. to 650 ° C., the resistive film forming composition B was put into the raw material supplier 16 and 1 g of the composition
Into the reaction tube 11 over 10 minutes, followed by 650 ° C.
While forming for 10 minutes, the composition A for forming a resistive film
Is placed in a raw material feeder 16 and 2 g of this composition
And then held at 650 ° C. for 10 minutes. Thus, the metal oxide resistance film 5 was formed on the surface of the substrate. The film thickness of the film 5 thus formed is usually several tens to several thousands nm, but in this embodiment, it is about 500 nm.
Met. Otherwise, a resistor was manufactured in the same manner as in Example 1.

Example 4 In this example, the resistor shown in FIG. 2 was manufactured using two types of compositions for forming a resistive film.
In a 200 ml Erlenmeyer flask, 10 g of indium triacetylacetonate (In (CH ₃ COCH ₂ COCH
₃ ) ₃ ) and aluminum triacetylacetonate (Al (CH ₃ COCH ₂ CO ₃ ) corresponding to 10 mol% of Al
CH ₃ ) ₃ ) was weighed and dissolved by adding 50 ml of ethanol to prepare a composition C for forming a resistive film. Also,
In a 200 ml Erlenmeyer flask, 10 g of indium triacetylacetonate (In (CH ₃ COCH ₂ COCH
₃ ) ₃ ) and tin dibutyl diacetylacetonate ((CH ₃ CH ₂ CH ₂ CH ₂ ) ₂ corresponding to Sn of 10 mol%)
Sn (CH ₃ COCH ₂ COCH ₃ ) ₂ ) and 50
Then, another kind of composition D for forming a resistive film was prepared.

Using the production apparatus shown in FIG. 3, the substrate 1 was placed in a reaction tube, and the composition C for forming a resistive film was placed in a raw material supplier 16. Air is used as the carrier gas and the gas flow rate is 1
Liter / min, and the heating temperature of the substrate 1 was 600 ° C. The heating temperature of the substrate 1 may be lower than the deformation temperature of the substrate 1 or the melting point of the resistance film. The higher the heating temperature, the better the film quality (crystallinity) of the resistance film obtained,
400-800 ° C is preferred. After holding the substrate 1 in the reaction tube 11 at 600 ° C. for 30 minutes, 15 g of the composition C for forming a resistive film is sent into the reaction tube 11 over 20 minutes, and then while the temperature is lowered from 600 ° C. to 500 ° C. Then, the composition D for forming a resistive film is put into a raw material supplier 16 and the composition 10
g was sent into the reaction tube 11 over 15 minutes. Then, 5
While holding at 00 ° C. for 10 minutes, the composition C for forming a resistive film is put into the raw material feeder 16, 10 g of this composition is fed into the reaction tube 11 over 15 minutes, and then the temperature is raised to 600 ° C. And held for 10 minutes to form a metal oxide resistance film 5. The film thickness of the resistance film 5 formed in this manner is usually several tens to several thousand nm, but in this embodiment, it is about 450 nm.
Met. Otherwise, a resistor was manufactured in the same manner as in Example 1.

Example 5 In this example, the resistor shown in FIG. 2 was manufactured using two types of compositions for forming a resistive film.
In a 200 ml Erlenmeyer flask, 10 g of zinc diacetylacetonate (Zn (CH ₃ COCH ₂ COCH ₃ ) ₂ )
And magnesium diacetylacetonate (Mg (CH ₃ COCH ₂ COCH ₃ ) ₂ ) corresponding to 5 mol% of Mg
Are weighed and dissolved by adding 50 ml of ethanol,
A composition E for forming a resistive film was prepared. Also, 200ml
10 g of zinc diacetylacetonate (Zn (CH ₃ COCH ₂ COCH ₃ ) ₂ ) and 5 g of In
mol% of indium triacetylacetonate (In (CH ₃ COCH ₂ COCH ₃ ) ₃ ) was weighed,
50 ml of ethanol was added and dissolved to prepare another composition F for forming a resistive film.

Using the manufacturing apparatus shown in FIG. 3, the substrate 1 was placed in a reaction tube, and the composition E for forming a resistive film was placed in a raw material supplier 16. Air is used as the carrier gas and the gas flow rate is 1
Liter / min, and the heating temperature of the substrate 1 was 550 ° C. The heating temperature of the substrate 1 may be lower than the deformation temperature of the substrate 1 or the melting point of the resistance film 5, and the higher the heating temperature is, the better the film quality (crystallinity) of the resistance film obtained is. ~ 600 ° C is preferred. After holding the substrate 1 in the reaction tube 11 at 550 ° C. for 30 minutes, 15 g of the composition E for forming a resistive film was sent into the reaction tube 11 over 20 minutes.
Subsequently, while the temperature was lowered from 550 ° C. to 400 ° C., the composition F for forming a resistive film was put into the raw material feeder 16 and 10 g of this composition was fed into the reaction tube 11 over 15 minutes. While holding for 10 minutes, the composition E for forming a resistive film is put into the raw material feeder 16, and 10 g of this is sent into the reaction tube 11 over 15 minutes, and then the temperature is raised to 500 ° C. for 10 minutes While holding, the metal oxide resistance film 5 was formed. The thickness of the resistance film 5 thus formed is usually several tens to several thousands nm, but in this embodiment, it was about 400 nm. Otherwise, a resistor was manufactured in the same manner as in Example 1.

Comparative Example 1 Without forming the metal oxide protective films 2 and 4, 3 g of the composition for forming the resistance film 3 was fed into the reaction tube 11 over 15 minutes. The thickness of the obtained resistance film 3 was about 450 nm. Otherwise, a resistor was manufactured in the same manner as in Example 1.

Comparative Example 2 Composition for forming resistive film
5 g was sent into the reaction tube 11 over 3 minutes. The thickness of the obtained resistance film 3 was about 80 nm. Otherwise, a resistor was manufactured in the same manner as in Comparative Example 1. Table 3 shows the characteristics of the resistors of Examples 3 to 5 and Comparative Examples 1 and 2.

[0032]

[Table 3]

As is apparent from the above results, a crystal having a high crystallinity composed of columnar crystal grains having a chemical composition distribution within the grains is grown on the insulating base material while being oriented in a certain crystal plane. By forming the metal oxide resistive film, it is possible to suppress the deterioration of the resistive film due to the diffusion of alkali ions and the electrochemical reaction with moisture, which are factors of the decrease in reliability due to the thinning for high resistance. it can.

[0034]

As described above, according to the present invention, a metal oxide film resistor having a wide range of resistance and a small TCR can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a metal oxide film resistor according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a cross section of a metal oxide film of the resistor.

FIG. 3 is a schematic vertical sectional view of a metal oxide film resistor according to another embodiment.

FIG. 4 is a schematic view showing a cross section of a metal oxide film of the resistor.

FIG. 5 is a cross-sectional view illustrating a schematic configuration of a metal oxide film manufacturing apparatus used in Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2, 4 Metal oxide protective film 3, 5 Metal oxide resistance film 6, 7, Cap terminal 8, 9 Lead wire 10 Protective film 11 Reaction tube 12 Furnace tube 13 Packing 14 Electric furnace 15 Composition for oxide film formation Object 16 Raw material supply device 17 Gas supply device 18, 19, 20 Pipe 21 Exhaust device

Claims (7)

[Claims] 1. A first metal oxide protective film comprising at least an insulating substrate, crystal grains grown on the substrate and oriented in a certain crystal plane to form a column, and a columnar crystal grown on the protective film. A metal oxide resistance film composed of crystal grains of the above, and a second crystal grain composed of columnar crystal grains grown on the resistance film.
A metal oxide film resistor comprising a metal oxide protective film of the above. 2. The metal oxide film resistor according to claim 1, wherein the film thickness of the first metal oxide protective film is equal to or greater than the film thickness of the second metal oxide protective film. 3. The metal oxide film resistor according to claim 1, wherein the first metal oxide protective film has an average thickness of 150 to 500 nm. 4. A metal oxide resistive film comprising at least an insulating base material and a columnar crystal grain having a chemical composition distribution within a particle, wherein the metal oxide resistive film is grown on the base material while being oriented in a certain crystal plane. A metal oxide film resistor comprising: 5. The method according to claim 1, wherein the metal oxide resistance film comprises tin oxide,
The metal oxide film resistor according to claim 1, comprising indium oxide or zinc oxide as a main component. 6. The method according to claim 1, wherein the metal oxide protective film comprises tin oxide,
The metal oxide film resistor according to any one of claims 1 to 3, comprising indium oxide, zinc oxide, or titanium oxide as a main component. 7. A step of forming a first metal oxide protective film composed of crystal grains grown in a columnar shape oriented on a predetermined crystal plane on an insulating substrate, wherein a columnar crystal grown on the protective film is formed. A step of forming a metal oxide resistance film composed of crystal grains,
A step of forming a second metal oxide protective film made of columnar crystal grains grown on the resistance film, and a step of annealing at a film forming temperature of the resistance film or higher. Manufacturing method of film resistor.