JPH04254301A - Resistor element and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a high quality resistor element with a superior yield and at a low cost which is used for a chip resistor, a variable resistor, a hybrid IC, a thermal printer head, etc. CONSTITUTION:A resistor element is constituted in a structure wherein a bismuth oxide based substratum film 4 is formed for a double oxide based resistance film 3 made of ruthenium and lead oxide, and a lead oxide based substratum film 4 is formed for a double oxide based resistance film 3 made of ruthenium and bismuth. These films are manufactured by printing and baking paste. Hence resistor material is not vaporized in a baking process, the resistance value yield is improved, and a thin oxide film resistor of high quality can be obtained at a low cost.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistor used in chip resistors, variable resistors, hybrid ICs, thermal print heads, etc., and a method for manufacturing the resistor.

0002

2. Description of the Related Art When a technique of forming a film of a corresponding metal oxide by thermal decomposition of a metal compound is applied to the production of a resistive film, a resistor having a small resistive film thickness and uniform crystal grain sizes can be obtained. For example, if you use a ruthenium compound,
Although the resistor has a larger sheet resistance than a resistor using a vapor-deposited metal film, it has better current noise characteristics, and since it is made of an oxide, it can also have better power resistance. At the same time, manufacturing equipment costs,
The running cost and raw material cost can also be kept lower than a process including a vacuum process because it is a simple process consisting only of printing and firing.

On the other hand, ruthenium oxide is a type of compound that sublimates at high temperatures, and is known to have a high vapor pressure. In particular, ruthenium double oxides, regardless of whether they are pyrochlore or perovskite, are thought to have extremely high vapor pressures at high temperatures. For example, according to experiments conducted by the inventors, when barium ruthenate or strontium ruthenate, which has a perovskite structure, is formed using silicon or quartz glass as a substrate by the method described above, 6
It is known that heating at 50° C. for 30 minutes completely evaporates and disappears from the substrate. Therefore, attempts were made to suppress the volatilization of substances by examining the material of the substrate and the firing conditions, but it was not possible to reduce to a practical level the variation in properties such as resistance within and between substrates caused by volatilization. There wasn't.

0004

[Problems to be Solved by the Invention] However, in order to satisfy the range required for the resistance value of the resulting resistor, the above-mentioned double oxide system, which has a volume resistivity that is about one order of magnitude higher than that of ruthenium oxide etc., must be used. Therefore, it is necessary to devise a method to improve the above-mentioned drawbacks of these substances.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate this drawback and to provide a resistor and a method for manufacturing the same, which can produce resistors with excellent electrical characteristics with little variation in characteristics.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a substrate, a first film mainly composed of bismuth oxide formed on the substrate, and a first film formed on the substrate. The second film is made of a composite oxide of ruthenium and lead formed in the above-described method, or a mixture thereof with other metal oxides for adjusting the temperature coefficient of resistance. Further, the present invention includes a base, a first film formed on the base and mainly composed of lead oxide, and a composite oxide of ruthenium and bismuth formed on the first film or a resistance temperature It is characterized by comprising a second film made of a mixture with other metal oxides for coefficient adjustment.

[0007] The manufacturing method of the present invention also includes the steps of applying or printing a paste consisting of an active agent consisting of a compound containing bismuth in its structure, a solvent, and a thickener onto a substrate and drying it, and drying the paste in the atmosphere. a step of firing at a temperature of 700°C or less to form the first film, and a mixture of only a compound containing ruthenium in its structure and a compound containing lead in its structure or a compound containing other metals in its structure. A process of coating or printing a paste consisting of an active agent, a solvent, and a thickener on the first film and drying it, and a process of heating and baking it are performed in sequence. A process of coating or printing a paste consisting of an active agent, a solvent, and a thickening agent on a substrate and drying it in the atmosphere at 700°C.
a step of firing at a temperature below to form a first film; A step of applying or printing a paste made of a thickening agent, a solvent, and a thickener onto the first film and drying the paste, and a step of heating and baking the paste are sequentially performed.

[0008]

[Operation] According to the present invention, a bismuth oxide-based first film which is reactive with both the substrate and the second film (resistor film) mainly composed of a composite oxide of ruthenium and lead is provided. Either a film is provided, or a lead oxide-based first film that is reactive with both of them is provided between the substrate and a second film (resistor film) mainly composed of a composite oxide of ruthenium and bismuth. It is a thing,
When the resistor film is fired, the oxide film mainly composed of bismuth oxide or lead oxide, which is provided as an underlayer, is melted, which has the effect of preventing the volatilization of components from the resistor film formed above.

The reason for this is that oxides whose main components are bismuth oxide and lead oxide have a low melting point, and when they are very small particles such as those forming a film formed by thermal decomposition of a metal compound, The melting point has further decreased and is much lower than the literature value (around 800°C), and there is a strong correlation between the volatilization of the resistor film and the softening point of the substrate.
This is because the lower the softening point of the base, the less volatilization of the resistor film.

[0010] In addition, in lead ruthenate, the lead ions at the 8-coordination site are easily replaced by bismuth ions, and in bismuth ruthenate, the bismuth ions are similarly easy to replace with lead ions, so such problems occur during firing of the resistive film. The reaction can be expected to have the effect of chemically suppressing volatilization of the resistor film.

The present invention provides a manufacturing method that can produce practical resistors with excellent electrical characteristics with small variations in characteristics by suppressing volatilization of substances through the above two mechanisms. can.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A resistor according to an embodiment of the present invention and a method for manufacturing the same will be explained in detail below.

(Embodiment 1) FIG. 1(a) shows a sectional view of a resistor of this embodiment. In the figure, 1 is a base, 2 is an electrode,
3 is a resistor film, and 4 is a base film. The resistor film 3 corresponds to a second film, and the base film 4 corresponds to a first film in the claims.

Next, a specific manufacturing method will be explained. As the substrate 1, a 96% alumina substrate glazed with barium borosilicate glass having a softening point of 725° C. is used. Next, a solution of commercially available rosin (product name Silvatac 140, manufactured by Arakawa Chemical) dissolved in an equal weight of terpineol (
A solution (hereinafter referred to as 5-bismuth paste) in which 5.0 wt% bismuth octylate (manufactured by Asahi Denka) was dissolved in a solution (hereinafter referred to as vehicle liquid) was applied onto a substrate using a screen printing plate with a stainless steel mask of 325 mesh. printed on. After drying this at 150° C. for 15 minutes, it was heated at a temperature increase rate of 30° C./min, held at each predetermined temperature for 10 minutes, and then fired in the air using a profile in which the temperature was lowered at the same rate. As a result, a pale yellow transparent bismuth oxide base film 4 having a thickness of about 300 Å is formed.

The X-ray diffraction pattern of this CuKα is shown in FIG.
Shown below. From FIG. 2, it can be seen that the δ-type bismuth oxide produced at temperatures below 500°C, as shown by the diffraction pattern 11, reacts with the silica contained in the glaze of the substrate 1, and at 600°C, the δ-type bismuth oxide is almost completely produced as shown in the diffraction pattern 12. It can be seen that it changes to bismuth silicate. When the firing temperature is further increased to 700° C., this bismuth silicate reacts with the glaze of the substrate 1 and becomes glassy as is clear from the diffraction pattern 13.

Next, the paste for forming the resistor film 3 is as follows:
Ruthenium octylate 0.6 per 20g vehicle liquid
A solution containing 0.616 g of lead octylate and 0.616 g of lead octylate (hereinafter referred to as
It is called 55RP paste. ), and in this 55RP paste, the ratio of ruthenium to lead is adjusted to 1:1 (this paste may also be fired with the same profile as the base film 4).

Next, in order to verify the effect of the base film 4 based on bismuth oxide, the resistor film 3 was coated as shown in FIG. 2(a).
1200 resistors were prepared for each substrate, and 100 resistors were sampled to examine the variation in resistance value. In order to estimate the volatilization of resistor components, they were formed on a transparent glass plate and the light transmittance at a wavelength of 540 nm was measured. The resistance value measurement sample was made by applying the same glass glaze as above to a 96% alumina substrate with slits for dividing.
), a baked silver-palladium electrode was used as the electrode 2. The size of one of these is 2.0 x 1.2
mm, and the effective size of the resistor is 0.6 x 0.7 mm. In addition, the light transmittance measurement sample was Corning's 7059, which has a similar composition to the glass glaze mentioned above, as the substrate 1.
A glass plate was used. The same 5-bismuth paste as described above was used as the paste for forming the bismuth oxide base film 4. It was confirmed by X-ray diffraction that the change in crystal structure due to the firing conditions as described above was also observed on the 7059 glass plate. Then, the resistor film 3 is formed using the aforementioned 55RP paste. Here, the base film 4 and the resistor film 3 were formed by changing the firing temperatures as listed in (Table 1), and the measurement results of their characteristics are shown in (Table 1).

[0018]

[Table 1]

In this table, CV is a parameter indicating variation, and is defined by (Equation 1).

[0020]

[Math 1]

From this table, it is clear that there is a correlation between the variation in resistance value and the light transmittance, and as the light transmittance increases (that is, the degree of volatilization of the resistor component increases), the variation in resistance value also decreases. You can see it getting bigger. The relationship between the firing conditions of the bismuth oxide film of the base film 4 and the variation in resistance value is as follows.
Regardless of the firing conditions of the resistor film 3, the variation increases at 700°C. This can be explained as follows, taking into account the results of the X-ray diffraction described above. When a bismuth oxide film is fired at 700°C, it becomes amorphous, but the resulting glass layer, although containing bismuth, is small in quantity (300 Å thick).
Therefore, it is expected that the composition is close to the barium borosilicate glass of Substrate 1. Therefore, the melting point (or softening point) increases and the effect of suppressing volatilization of resistor components decreases, resulting in an increase in resistance value variations. Comparing this data with the data of the resistor film in the comparative example in which no base film was formed, which is shown in the rightmost column of Table 1, it is judged that there is still some effect of suppressing volatilization. This seems undesirable from a practical standpoint. From the above, it can be seen that the base bismuth oxide film should be fired at a temperature of 700°C or lower, preferably around 600°C.

Furthermore, the firing conditions for the bismuth oxide film of the base film 4 were fixed at 600° C. for 10 minutes (therefore, the film was made of bismuth silicate), and the ratio of ruthenium to lead in the resistor paste was varied. The average resistance value and variation were investigated by changing the firing conditions in the same manner as described above. At this time, a paste was prepared by mixing at the compounding ratio shown in Table 2 so that the metal compound concentration in the resistance paste was the same as that of the 55RP paste. The type of substrate and the number of samples sampled were the same as in the previous study. The results are shown in (Table 2).

[0023]

[Table 2]

Furthermore, in order to clarify the effect of such a bismuth oxide film, the same sample as in the study shown in Table 2 was prepared without the bismuth oxide film, and the same evaluation was performed. The results are shown in Table 3 as a comparative example.

[0025]

[Table 3]

As clearly judged from Tables 2 and 3, when a bismuth oxide film is provided as a base, the CV value is small and there is an effect of reducing variations in resistance value. This effect appears almost regardless of the ratio of ruthenium to lead contained in the resistor, and seems to demonstrate the validity of the mechanism intended by the present inventors.

As described above, according to this embodiment, the bismuth oxide film for preventing volatilization is used as the base and the firing temperature is 700.
By forming the resistor at a temperature of 0.degree.

(Example 2) Based on the above study, as a second example of the present invention, various metals were added to the resistor film 3 for the purpose of adjusting the temperature coefficient of resistance. This was done by adding organic compounds of various metals into the paste, and the metal concentration in the paste was adjusted to be similar to the 55RP paste. The metals studied include Co, Fe, Ni, Mn, Ti, In, Cu,
V, Cr, Zn, Cd, Sn, Ag, Y, Zr, Nb,
Examples of the organic group include Rh, Pt, La, Ce, Au, Ca, Sr, and Ba, and examples of the organic group include octylic acid, acetylacetone, and alkoxide. A resistor was formed on the substrate 1 (1200 pieces per substrate as above) on which a bismuth oxide film was formed at 600°C for 10 minutes using a paste containing these metals at 700°C for 10 minutes. When film 3 was created and the variation in resistance value was evaluated,
It was found that all compositions had CV values as shown in Table 2. However, the composition contains a very large amount of the above metals (approximately 50% of the total of ruthenium and lead).
mol% or more), some samples have CV values exceeding 10%, and it is recommended to use transition metals such as Co, Fe, Ni, Mn, and V, which are effective even when added in small amounts, to adjust the temperature coefficient of resistance. Seems desirable. As a result, ruthenium 45 mol%, lead 45 mol%, manganese 10 mol%
Using a paste with a composition of %, the average resistance value was 7.4 kΩ.
/□, CV value 5.2%, resistance temperature coefficient 15ppm/℃ (
It was possible to manufacture a resistor with characteristics of (average temperature between -55°C and 125°C).

(Embodiment 3) A third embodiment of the present invention will be described below.

[0030] Lead octylate (manufactured by Hanui Chemical Co., Ltd.) in the vehicle liquid
was dissolved to a concentration of 7.0 wt%, and this was used as a paste for forming a lead oxide film. After printing and drying on the same substrate as in the first embodiment, baking is performed in the same manner to form the base film 4. When the crystal phase formed in this film was examined by X-ray diffraction, it was found that
It was found that from 500°C to 650°C it is lead oxide, and at 700°C it is amorphous.

[0031] Then, 0.6 g of ruthenium octylate and 0.86 g of bismuth octylate were added to 20 g of vehicle liquid.
A resistor film 3 is formed in exactly the same manner as in the first embodiment using a paste prepared by dissolving the 55RB paste (hereinafter referred to as 55RB paste). The same study as in the first embodiment was conducted to investigate the effect of the lead oxide based base film 4 on the ruthenium and bismuth double oxide based resistor film 3.
Almost the same results as in Example 1 were obtained.

Further, as a result of adding a transition metal additive according to the second embodiment to adjust the temperature coefficient of resistance, it was found that 60
A lead oxide based base film was formed at 0°C for 10 minutes, and 42.5 mol% of ruthenium, 42.5 mol% of bismuth,
By forming a film with a composition of 15 mol% cobalt at 700°C for 10 minutes, the average resistance was 5.25 kΩ/□, C
A resistor having characteristics of a V value of 2.3% and a resistance temperature coefficient of 3 ppm/°C was manufactured.

As described above, according to this embodiment, a lead oxide film for preventing volatilization is formed as a base at a firing temperature of 700° C. or less, and a ruthenium and bismuth double oxide film is formed on top of it as a resistor. By providing this, it is possible to manufacture a resistor whose resistance value variation is at a practical level.

In the above embodiments, the resistor structure shown in FIG. Figure 2
Even if the structure shown in (b) (electrode post-installation type) is used, the same effects as in the example can be obtained.

Furthermore, as can be inferred from the fact that the purpose of the present invention is to suppress volatilization of resistor components during the firing process, the structure in which the resistor film 24 and the film 25 are provided in the opposite positional relationship in FIG. We also considered the following. In this case, the process involves first firing the resistor film at a temperature (400 to 500°C) at which the volatilization of substances from the resistor film is not severe, and then printing, drying, and firing the film 25, but at a low temperature. Since the strength of the resistor film is low due to being fired, the resistor film may be damaged or peeled off from the base during the process of forming the film 25.

Regarding the substrate 1, as is clearly judged, any material can be used as long as it has heat resistance of about 800 to 900°C, but if the thickness of the formed film is 300 to 1000 Å, Because it is small, care must be taken to ensure its surface smoothness. For example, if the surface of a commercially available 96% alumina substrate is used, the resistance value will increase and the variation will increase compared to the case where a glazed surface is used. In particular, when manufacturing a heating resistor for a thermal print head, which requires extremely precise control over variations in resistance, the smoothness of the surface of the substrate 1 must be carefully evaluated.

[0037]Also, in the above examples, a paste vehicle in which rosin was dissolved in α-terpineol was used, but this was because the printing method applied in this example was screen printing. Yes, solvents and resins can be selected and adjusted to suit other types of printing. The metal compound as a raw material should also be selected accordingly, and is not limited to the compound selected in this example.

As described above, according to this embodiment, a resistor with excellent electrical characteristics with a resistance value of 5 to 7 Ω/□ and a resistance temperature coefficient close to 0 ppm/°C can be manufactured at a low cost and in a practical manner. It becomes possible to manufacture with a high yield, which has a great industrial effect.

[0039]

As described above, the present invention provides a resistor and a method for manufacturing the same, which reduce volatilization of the resistor material during the firing process and can produce a resistor with excellent electrical characteristics with little variation in characteristics. can be provided.

[Brief explanation of the drawing]

[Fig. 1] (a), (b) Cross-sectional views showing the structure of a resistor according to an embodiment of the present invention.

[Fig. 2] Characteristic diagram of X-ray diffraction using CuKα showing changes in crystal phase depending on firing temperature of bismuth oxide film in the first embodiment of the present invention.

[Explanation of symbols]

1 Base 2 Electrode 3 Resistor film 4 Base film

Claims (4)

[Claims] Claim 1: A base body, a first film formed on the base body mainly composed of bismuth oxide, and a composite oxide of ruthenium and lead formed on the first film, or only a resistance temperature. A resistor comprising a second film made of a mixture with another metal oxide for coefficient adjustment. [Claim 2] A base, a first film mainly composed of lead oxide formed on the base, and a composite oxide of ruthenium and bismuth formed on the first film or a resistance temperature. and a second film made of a mixture with another metal oxide for coefficient adjustment. 3. A step of coating or printing a paste consisting of an active agent consisting of a compound containing bismuth in its structure, a solvent, and a thickener on a substrate and drying the paste at 700° C. in the atmosphere.
A step of firing at a temperature below to form a first film; 2. The resistor according to claim 1, wherein the steps of applying or printing a paste made of a thickener, a solvent, and a thickener onto the first film and drying the paste, and heating and baking the same are performed in sequence. Production method. 4. A step of applying or printing a paste consisting of an active agent consisting of a compound containing lead in its structure, a solvent, and a thickening agent onto a substrate and drying the paste at a temperature of 700°C or less in the atmosphere. a step of firing to form a first film, and an active agent and a solvent consisting of only a compound containing ruthenium in its structure and a compound containing bismuth in its structure or a mixture of a compound containing other metals in its structure. 3. The method of manufacturing a resistor according to claim 2, wherein the steps of applying or printing a paste containing a thickener on the first film and drying the paste, and heating and baking the paste are sequentially performed.