JPH02146703A - Manufacture of thin film resistor - Google Patents

Abstract

PURPOSE:To obtain a manufacturing method for a resistor which has a small change rate in resistance with changes in temperature and has characteristics that are superior in its high resistivity and not only make its film thin and its shape compact but also its yielding rate high by forming its oxide layer through drying and burning its layer after making to adhere a specific nitrate solution to the surface of a heat-resisting insulating substrate and performing the patterning of the oxide layer. CONSTITUTION:After making to adhere a nitrate solution containing Bi, Si, and Cu as well as at least a kind of ingredients selected out of a group consisting of Cd, Zn, Mg, and Hg to the surface of a heat resisting insulating substrate, its substrate is dried. Then it is fried at a temperature 800-870 deg.C in an atmosphere of oxidation to form an oxide layer consisting of Bi-Sr-M (although M is Cd, Zn, Mg, and/or Hg)-Cu-O and the patterning of its oxide layer is performed. For example, a powder in which combined quantities of 1/2 mol Bi2O3, 1mol SrO, 1mol CdO, 2mol CuO are dissolved into nitric acid. An alumina substrate is immersed in a diluted nitric acid solution and its treatment makes its nitric acid solution stick to the alumina substrate. After drying its solution, its substrate is fired at a temperature 850 deg.C and then a resister shown in Fig. is obtained by patterning the formed thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a thin film resistor suitable for being incorporated into high-density and highly integrated elements in the field of electrical and electronic materials.

[Prior Art] Conventional resistors include solid resistors, thick film paste resistors, and metal thin film resistors.

However, since this solid resistor has a thick shape, a large space is required for its arrangement.

Further, although thick film paste resistors are smaller in size than the solid resistors, since they are formed by printing, they cannot be manufactured to a thickness thinner than the thickness determined by printing technology. For this reason, thick film paste resistors have a large cross-sectional area, so
In order to obtain high resistance, it is necessary to mold the material into an extremely long shape. Therefore, it is not possible to obtain a resistor whose formation area is small. Further, there is also the problem that variations in resistance value tend to occur due to printing unevenness, resulting in poor yield.

Furthermore, since metal thin film resistors have a low specific resistance, it is necessary to mold extremely long thin film resistors in order to obtain high resistance. For this reason, the area in which it is formed becomes large, and it is also difficult to miniaturize it. Another drawback is that metal thin film resistors have a large temperature coefficient, and their resistance value tends to fluctuate due to temperature fluctuations.

Against this background, the inventors of the present application have developed B i -
A resistor made of Sr-Cd-Cu-0 based oxide was proposed (Japanese Patent Application No. 11i3-70293). This B1
-Sr-Cd-Cu-0-based oxides have excellent properties such as a small temperature coefficient of resistance over a wide temperature range, an extremely small rate of change in resistance due to temperature, and an extremely high specific resistance value.

[Problems to be Solved by the Invention] However, since oxide resistors are usually manufactured by sintering a powder compact, there is a problem in that it is difficult to reduce the thickness of the oxide resistor.

The present invention has been made in view of such problems, and includes:
To provide a method for manufacturing a thin film resistor which uses an oxide having excellent characteristics of low resistance change rate due to temperature and high specific resistance as a constituent component, can be made thinner and smaller, and has a high yield. With the goal.

[Means for Solving the Problems] A method for manufacturing a thin film resistor according to the present invention includes B t +Sr
A nitrate aqueous solution containing Cu and at least one component selected from the group consisting of CD, Zn, Mg and Hg is attached to the surface of the heat-resistant insulating substrate, and then dried,
Next, it is fired in an oxidizing atmosphere at 800 to 870°C to form a BiBl-Sr- (where M is Cd, Zn, Mg and/or Hg)-Cu-0 based oxide layer, and this oxide layer is patterned. It is characterized by

In addition, another method for manufacturing a thin film resistor according to the present invention includes Bi
A La-Sr-M-Cu-0 based oxide layer is formed by using a nitrate aqueous solution containing La instead of the nitrate aqueous solution containing La.

Furthermore, still another method of manufacturing a thin film resistor according to the present invention is as follows:
By using a nitrate aqueous solution containing Bi and a nitrate aqueous solution containing La, B 1-La-Sr −
This forms an M-Cu-0 based oxide layer.

[Function] In the present invention, since each element of B i+ S r+ Cd and Cu constituting the B i-Sr-Cd-Cu -○-based oxide is in an aqueous solution of its nitrate, the constituent elements of this oxide are finely dispersed in this nitrate aqueous solution. Therefore, when this aqueous solution is applied to the surface of a heat-resistant insulating substrate and at least a portion of this surface is covered with the aqueous solution, B 11 S r+ C is present on the substrate surface.
Since the aqueous solution with a uniform thickness is deposited with the constituent elements of d and Cu uniformly dispersed, an extremely thin B1-Sr-Cd-Cu-0 is formed by drying and firing.
oxide resistor films are formed with high yield.

As mentioned above, this B1-Sr-Cd-Cu-0 based oxide resistor has a small temperature coefficient of resistance and an extremely high specific resistance, so the present invention can improve the performance of thin film resistors with such excellent characteristics. It can be manufactured with high yield.

In this way, oxides with a small temperature coefficient of resistance, a small rate of change in resistance due to temperature, and an extremely high specific resistance are not limited to those of the above-mentioned type, but also those of the following types with similar characteristics. shows.

B i -Sr -M-Cu-0 system La-5r -M-Cu-0 system B 1-La-Sr -M-Cu-0 system, where M is Cd
+ Znl At least one element selected from the group consisting of Mg and Hg.

That is, Cd + Z n + M g and Hg are used alone or in combination of two or more of these elements.

[Example code] The present invention will be explained in more detail below.

In the present invention, B i -Sr -M-Cu-0 based oxide, La-Sr -M-Cu-0 based oxide or B
A thin film resistor of 1-La-Sr-M-Cu-0 based oxide is formed. However, M is Cd or Zn.

At least one component selected from the group consisting of Mg and Hg.

In Figure 1, the horizontal axis represents temperature, and the vertical axis represents the resistance change rate based on the resistance value at 27°C.
FIG. 3 is a graph showing the rate of change in resistance value of i and/or La-Sr-M-Cu-0-based oxides. Note that this first
The figure shows, as an example, measurements of a BiS r-Cd-Cu-0 based oxide containing 0.5 mol of Bi2O3, 1 mol of SrO, 1 mol of CdO, and 2 mol of CuO.

As is clear from FIG. 1, B iS r −Cd
-The resistance value of Cu-0 type oxide is from -220℃ to 150'
The resistance change rate is small over an extremely wide temperature range of C,
In this temperature range, the temperature coefficient of resistance is 4X10-'/
'C' is extremely small. Therefore, the resistance value does not fluctuate even when the temperature changes, and it has extremely excellent characteristics as a resistor used in various applications. In addition, this oxide has a specific resistance of 7500 μΩ·am, which is about 1.5 times the specific resistance of a conventional commonly used resistor. As described above, the resistance value (specific resistance) itself is large, and this oxide resistor also has favorable characteristics in this respect.

In addition, as mentioned above, BI Sr Cd Cu-○
Outside the system, Zn was added instead of Cd in this system.

System containing Mg or Hg, or Cd+Zn+M
In systems containing two or more types of g or Hg, in systems containing La in place of Bi in these systems, and in systems containing both Bi and La in place of Bi in these systems. , excellent characteristics similar to those shown in FIG. 1 can be obtained.

Furthermore, the specific resistance of all these systems is 7500 μΩ・cm.
That's high.

Conventionally, insulators or semiconductors have been obtained by combining various oxides. In this case, B1-Sr-Ca-C
When an oxide with a superconducting oxide composition such as the u-0 system is cooled to liquid nitrogen or liquid helium temperature, even if the composition is the same, it will exhibit superconducting properties if the manufacturing conditions are different. The electrical resistance becomes O, or exhibits semiconductor-like characteristics and increases near the temperature of liquid helium.

However, when the inventors of the present application were repeating trial production experiments to develop functional materials made of various oxides including superconducting oxides, they discovered that Cd oxide was substituted for Ca oxide in the above-mentioned superconducting oxide composition. 812
03, S r 01 B i -Sr-Cd-Cu-0 obtained by combination of oxides of CdO and CuO
It has been found that the oxides of the system result in resistors that exhibit neither metallic nor semiconducting characteristics. In addition, this type of oxide has a high resistance value and, as shown in FIG. 1, has a substantially constant resistance value over an extremely wide temperature range. Also, instead of CdO, ZnO, MgO
Or add HgO, or add these CdO, ZnO
The same holds true when two or more oxides of , MgO, or HgO are added.

Furthermore, in each prefecture mentioned above, instead of Bi2O3, L
The same applies when a2O3 and/or Bi20a is added.

In this way, the mechanism by which the resistance value remains constant regardless of temperature changes due to the combination of this type of oxide is that the tendency of increase/decrease in lattice vibration due to temperature change and the tendency of increase/decrease in electron conduction using lattice defects are just as wide. This is thought to be because they act in a compensating manner over a temperature range, but this mechanism has not necessarily been fully elucidated.

However, through extensive experimental research by the inventors of the present application, it has been experimentally determined that the resistance value of the above-mentioned oxides remains constant over a wide temperature range.

In particular, by combining the oxides in the following molar ratio, the above-mentioned resistance characteristics can be further improved.

Bi2O3 and/or La203; 0.25 to 1
．． 5 mol, SrO; 0.5 to 2.5 mol 1/; CdO, ZnO, MgO or HgO; 0.5 to 2 mol; Cub; ] to 4 mol.

In addition, when adding oxides of CdO, ZnO, MgO, or HgO in combination, the total amount is 0.5 to 2 moles. Also, when Bi2O3 and La2O3 are added in combination, the total amount is 0.25 to 1.5 mol.

Therefore, the constituent elements of this Bi (and/or La)-Sr-M (M is at least one component selected from the group consisting of Cd+Zn1Mg and Hg)-Cu-O based oxide are included in the nitrate aqueous solution. to the surface of the heat-resistant insulating substrate.

Specifically, the aqueous solution may be attached to the substrate surface by immersing the substrate in the nitrate aqueous solution, or the nitrate aqueous solution may be dropped onto the surface of the substrate and the aqueous solution may be applied by a so-called spin quarter method. may be attached to the surface of the substrate. That is, by dropping an aqueous nitrate solution onto the surface of the substrate and rotating the substrate around an axis perpendicular to the surface, the droplets of the aqueous nitrate solution are spread thinly on the substrate, thereby forming a thin layer of the aqueous solution. In any case, since the oxide composition is deposited on the substrate as an aqueous solution, its thickness is uniform. Furthermore, since it is supplied onto the substrate as an aqueous solution, it is easy to form a thin oxide resistance layer by making the aqueous solution layer thin.

When the aqueous solution is attached to the substrate by immersing the substrate in the aqueous solution, the thickness of the aqueous solution layer can be adjusted to a desired value by adjusting the concentration and viscosity of the aqueous solution. can. Furthermore, when forming an aqueous solution layer by the spin quarter method, the layer thickness can be adjusted by adjusting the rotation speed of the substrate, etc.

Next, after forming an aqueous solution layer on the surface of the substrate as described above, this is dried and further heated to a temperature of 800 to 870° C. and fired. If this firing temperature is less than 8 oo'c, the oxide will not be fired sufficiently, and BI (and/or La)-Sr
-Sufficient characteristics as an M-Cu-0 based oxide resistor cannot be obtained. On the other hand, when the firing temperature exceeds 870° C., variations occur in the resistance values of the formed resistors. Therefore, the firing temperature needs to be 800 to 870°C. By this firing process, Bi (and/or La)-Sr-M-Cu
A thin film of -0-based oxide is formed over the entire surface of the substrate.

Next, this oxide thin film is patterned using photolithography technology to obtain a thin film resistor of a predetermined shape.

The oxide thin film resistor thus formed is made of Bi(
and/La) -Sr-M-Cu-0 system oxide, so as mentioned above, it has extremely high specific resistance, and has a small temperature coefficient of resistance over a wide temperature range, and small fluctuations in resistance value due to temperature. .

Moreover, since each constituent component of the oxide is deposited on the substrate surface while being uniformly dispersed in the nitric acid aqueous solution, an extremely uniform thin oxide film can be obtained.

Therefore, the length of the resistor to obtain a desired resistance value can be shortened, and a minute thin film resistive element can be manufactured.

Next, by the method of the present invention, Bi (and/or La)
The results of manufacturing a -Sr-M-Cu-0 based oxide thin film resistor will be explained. First, a powder containing 172 moles of Bi2O3, 1 mole of SrO, 1 mole of CdO, and 2 moles of CuO was dissolved in 5 parts of nitric acid and diluted with 5 parts of water to prepare a nitric acid aqueous solution. An alumina substrate was immersed in this nitric acid aqueous solution, and then the substrate was pulled up to adhere the nitric acid aqueous solution to the substrate surface. Next, after drying the nitric acid aqueous solution on this substrate, it was heated to 850° C. for 3 hours and subjected to baking treatment, and a thin film with a thickness of 0.1 μm was formed.

This thin film was patterned by photolithography to form a resistor as shown in FIG. The width of this resistor is 10 μm, and the interval between each resistor is also 10 μm. Also, the formation area of this resistor is 1 mII in length + 1 m II in width.
There are two issues. Although the resistor thus obtained was minute, it had an extremely high resistance value of 3 MΩ.

Note that when the nitric acid aqueous solution was dropped onto an alumina substrate and a thin film was formed by the spin quarter method, a fine resistance element with a high resistance value was similarly obtained.

La2 instead of Bi2O3 or a part thereof
Similar effects were obtained when O3 was used and ZnO, MgO, or HgO was used alone or in combination in place of CdO.

[Effect of the invention] According to the present invention, Bi (and/or La)Sr-M-
An extremely thin film of Cu-0-based oxide can be stably and uniformly formed. Furthermore, since the constituent elements of this oxide are finely dispersed in the nitric acid aqueous solution, the obtained resistor has small variations in resistance value and has a high yield.

Furthermore, since the film is fired at a temperature of 800 to 870° C., the strength of the thin film is sufficiently high, and therefore the variation in resistance value is low and the yield is high.

Furthermore, Bi (and/or La)-Sr-MCu-0
The specific resistance of oxides is several thousand times higher than that of metal thin film resistors, so it is possible to obtain extremely small and thin resistance elements, which contributes to the high integration and density of electronic devices in which these resistance elements are incorporated. .

Moreover, since the temperature coefficient of resistance is small, a resistance element with small resistance value fluctuation can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the temperature change rate of the resistance value of B i -Sr-Cd-Cu-0 based oxide, and FIG. 2 is a diagram showing the pattern of the resistance element formed in the example.

Claims (3)

[Claims] (1) Bi, Sr and Cu, Cd, Zn, Mg and H
A nitrate aqueous solution containing at least one component selected from the group consisting of -Sr-M (where M is Cd, Z
1. A method for manufacturing a thin film resistor, comprising forming an oxide layer of n, Mg and/or Hg)-Cu-O system, and patterning this oxide layer. (2) La, Sr and Cu, Cd, Zn, Mg and H
A nitrate aqueous solution containing at least one component selected from the group consisting of La -Sr-M (where M is Cd, Z
1. A method for manufacturing a thin film resistor, comprising forming an oxide layer of n, Mg and/or Hg)-Cu-O system, and patterning this oxide layer. (3) Bi, La, Sr and Cu, and Cd, Zn, Mg
A nitrate aqueous solution containing at least one component selected from the group consisting of Bi-La-Sr-M (however,
A method for manufacturing a thin film resistor, characterized in that M is Cd, Zn, Mg and/or Hg)-Cu-O based oxide layer is formed and this oxide layer is patterned.