JP2005116804A - Metal resistor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal resistor several times higher in volume resistivity than conventional metal resistors such as Ni-Cr or Fe-Cr-Al alloys, high in precision or low in temperature coefficient of resistance, and excellent in heat resistance and corrosion resistance. <P>SOLUTION: The metal resistor comprises 10-15 mass% V, 12-16 mass% Al, 1-30 mass% Cr, and Fe as the rest substantially. The alloy for the metal resistor has a temperature coefficient of resistance of ≤200 ppm/°C in absolute value in the range of -25 to 125°C and exhibits a volume resistivity of ≥400 μΩcm. For the formation of a thin film metal resistor, the sputtering target of the same composition is used, the treatment chamber is evacuated to ≤1.0×10<SP>-4</SP>Pa, and sputtering is performed in an Ar atmosphere. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal resistance material used for a thin film resistor such as a thin film resistance element.

  Metal resistance materials such as metal resistors, metal thin film resistors, and sputtering targets are required to have a large volume resistivity, a small resistance temperature change, and a relatively strong resistance to repeated cold heat. Among these metal resistance materials, Ni-Cr-based and Fe-Cr-Al-based alloys have a relatively large volume resistivity, a small temperature coefficient of resistance (TCR), and are excellent in heat resistance and corrosion resistance. Since it is excellent, it is widely used as a thin film resistor for electronic parts.

  However, the volume resistivity of Ni—Cr and Fe—Cr—Al alloys is at most about 150 μΩcm. In order to obtain a large resistance with these alloys having a relatively small volume resistivity, it is necessary to reduce the thickness of the thin film resistor and make the pattern finer. However, when the thin film resistor is thinned or the pattern is miniaturized, there are problems that thermal stability and resistance accuracy are deteriorated and rated power is lowered.

  For the above reasons, the resistance value that can be realized with a Ni—Cr-based or Fe—Cr—Al-based alloy thin film resistor is naturally limited.

  Recently, materials having the following high resistance have been found.

1) It has a high resistance of about several thousand μΩcm at room temperature, but has a large negative resistance temperature coefficient, containing Fe as a main component, 26.9% by mass of V, and 14.2% by mass of Al, Fe ₃ A Heusler-type intermetallic compound (Fe ₂ VAl) material obtained by substituting a part of Fe of Al with V (see Non-Patent Document 1).

2) An intermetallic compound (Fe _2.7 V) having a low temperature coefficient of resistivity but having a specific resistance at room temperature of about 200 μΩcm and containing Fe as a main component, V of 7.9% by mass, and Al of 14.1% by mass. _0.3 Al) material (see Non-Patent Document 2).

  However, when these Fe-V-Al materials are used as metal resistors, there are problems in specific resistance and resistance temperature coefficient, respectively, and oxidation resistance and heat resistance are low. Therefore, from these materials, However, high-resistance small electronic parts cannot be obtained.

From the above situation, there has been a demand for a metal resistance material that achieves a high specific resistance and a low temperature coefficient of resistance and has excellent heat resistance and corrosion resistance in miniaturization and thinning of thin film resistors.
Physical Review Letters, Vol. 79, 1997, p. 1909-1912 Journal of Physics: condensed Matter, Vol. 12, 2000, p. 1769-1779

  The object of the present invention is to have a volume resistivity several times that of a conventional metal resistor such as a Ni-Cr-based or Fe-Cr-Al-based alloy, a highly accurate or low resistance temperature coefficient, and an excellent An object of the present invention is to provide a metal resistor exhibiting heat resistance and corrosion resistance, particularly a thin film resistor, and a method for producing the same.

  The metal resistor according to the present invention is an alloy containing V: 10 to 15% by mass, Al: 12 to 16% by mass, Cr: 1 to 30% by mass, and the balance being substantially Fe. The absolute value of the temperature coefficient of resistance at 125 ° C. is 200 ppm / ° C. or less, and the volume resistivity is 400 μΩcm or more.

  The metal resistor according to the present invention is useful in the form of a thin film.

  In order to manufacture a metal resistor in the form of a thin film according to the present invention, that is, a thin film resistor, sputtering is used, and sputtering targets therefor are: V: 10-15% by mass, Al: 12-16% by mass, Cr : 1 to 30% by mass, with the balance being substantially Fe.

In the method of manufacturing a thin film resistor according to the present invention, the sputtering target is used, and the inside of the chamber is evacuated to 1.0 × 10 ⁻⁴ Pa or less during sputtering, and then sputtering is performed in an Ar atmosphere.

  The metal resistor according to the present invention has a volume resistivity several times higher than conventional Ni—Cr and Fe—Cr—Al alloys and the like, and the temperature coefficient of resistance is as high as ± 200 ppm / ° C. or less. It is accurate and has excellent heat resistance and corrosion resistance. Therefore, by using the metal resistor of the present invention, it is possible to easily realize a thin film resistor having a high resistance, that is, a stable and high resistance, which has conventionally been difficult to realize.

  In order to achieve the above-mentioned object, the present inventors have conducted intensive research on the material composition and the manufacturing method of the metal resistor, and as a result, only at a specific material composition and film formation conditions, a high specific resistance and a low resistance temperature. It has been found that a thin film resistor having a coefficient and good heat resistance and corrosion resistance can be obtained, and the present invention has been completed.

  Hereinafter, for the metal resistor, thin film resistor, sputtering target, and manufacturing method thereof according to the present invention, reliability such as resistance temperature coefficient, volume resistivity, heat resistance, corrosion resistance, reliability, thermal stability / resistance accuracy, etc. Will be described in detail.

  The metal resistor of the present invention is an alloy containing Cr: 1 to 30% by mass, V: 10 to 15% by mass, Al: 12 to 16% by mass, and the balance being substantially made of Fe.

  The Fe—V—Al—Cr alloy having this composition has a metal resistivity that is several times higher than that of the Ni—Cr system, has a small resistance temperature coefficient, and has almost the same reliability as the Ni—Cr system. A material is obtained.

  That is, Cr: 1 to 30% by mass, V: 10 to 15% by mass, Al: 12 to 16% by mass, and the balance is substantially Fe, so that the volume resistivity is 400 μΩcm or more. The resistance temperature coefficient at −25 to 125 ° C. can be as small as ± 200 ppm or less, which can be as small as that of the conventional Ni—Cr system.

  As the amount of V increases, the resistance increases, the temperature coefficient of resistance becomes negative, and the semiconductor electrical resistance behavior is exhibited. Therefore, when V is less than 10% by mass, the volume resistivity becomes as small as 400 μΩcm or less, and the resistance temperature coefficient becomes +200 ppm / ° C. or more. Moreover, when V is added exceeding 15 mass%, although a volume resistivity will become large, a resistance temperature coefficient will be set to -200 ppm / degrees C or less.

  Al does not contribute to the resistance change as much as V, but, like V, affects the resistance temperature coefficient change. When Al is less than 12% by mass, the temperature coefficient of resistance becomes +200 ppm / ° C. or more. When Al is added in excess of 16% by mass, the temperature coefficient of resistance becomes −200 ppm / ° C. or less.

  Cr rapidly forms a dense and stable Cr oxide film on the surface, thereby suppressing embrittlement due to hydrogen generated by the reaction between Al and moisture and protecting the material from the atmosphere. If Cr is less than 1% by mass, sufficient embrittlement suppressing effect and corrosion resistance improving effect cannot be obtained. On the other hand, when Cr exceeds 30% by mass, the temperature coefficient of resistance becomes −200 ppm / ° C. or less, and the temperature change becomes large.

By setting the sputtering target to the composition of the present invention, the same characteristics can be obtained even in a thin film resistor formed on a substrate by sputtering or the like. However, when a thin film resistor is manufactured by sputtering, it is necessary to evacuate the chamber to 1.0 × 10 ⁻⁴ Pa or less and then perform sputtering in an Ar atmosphere. This is because Al is very easy to oxidize, and if the amount of residual oxygen in the chamber is large, Al is oxidized during sputtering, and a thin film resistor having the desired resistance cannot be obtained.

  The metal resistor according to the present invention is excellent in stability when held in a high temperature atmosphere for a long time. That is, by adding Cr, a stable oxide film is formed on the surface, and resistance change due to oxidation is suppressed.

(Examples 1-4, Comparative Examples 1-6, Conventional Example 1)
Using 99.9% or more pure vanadium, aluminum, electrolytic iron, and electrolytic chromium as raw materials, weigh each composition of Examples 1 to 4 and Comparative Examples 1 to 6 shown in Table 1 and dissolve them in an Ar plasma arc. Approximately 1000 g of ingot was produced. After homogenizing each, a bulk sample having a thickness of 2 mm, a width of 5 mm, and a length of about 40 mm was cut by wire cutting, and this was used as a resistance measurement sample. Table 1 shows the composition analysis values of the ingots produced.

As a conventional example, an ingot was similarly prepared for a Ni—Cr alloy, and a composition analysis was performed.

About the cut-out sample, resistance measurement was performed at room temperature by the 4-terminal method, and the volume resistivity was calculated from the measured resistance value and the dimension of the sample. Moreover, resistance measurement was performed while heating up in a thermostat, and the temperature coefficient of resistance at −25 to 125 ° C. was obtained. The results are shown in Table 2.

  From the measurement results, Examples 1 to 4 in the composition range defined in the present invention all had a volume resistivity of 400 μΩcm or more, and showed a temperature coefficient of resistance equivalent to that of Ni-Cr alloy Conventional Example 1. .

  In Comparative Example 4 with a small amount of V, the volume resistivity was low. In Example 3 with a large amount of V, the volume resistivity was large, but the temperature coefficient of resistance was as large as -450 ppm / ° C. In Comparative Examples 5 and 6 in which the Al amount deviates from the specified range, or in Comparative Example 2 in which the Al amount and Cr amount deviate from the specified range, the absolute value of TCR exceeds ± 200 ppm / ° C. It was. Comparative Example 1 with only a small amount of Cr showed good volume resistivity and resistance temperature coefficient.

  Next, the sample after the resistance measurement was heated in the atmosphere at 300 ° C. for 30 minutes, and the change in the surface was observed.

  It can be seen that, among Examples 1 to 4, Comparative Examples 1 to 6, and Conventional Example 1, except for Comparative Example 1, there is no change in the surface after heating, and there is no problem in corrosion resistance and oxidation resistance. Comparative Example 1 having a low Cr content turned red and black and had insufficient corrosion resistance.

  Therefore, only in the composition range specified in the present invention, a volume resistance, a temperature coefficient of resistance, a heat resistance and a corrosion resistance were all good and a stable resistor was obtained.

Next, in order to manufacture a thin film resistor, a round plate having a thickness of 3 mm and a diameter of 80 mm was cut from the ingots of Examples 1 to 4, Comparative Examples 1, 3, 4 and Conventional Example 1 and the upper and lower surfaces were ground. And targeted. Using these targets, a film was formed on a quartz glass substrate with a DC sputtering apparatus. Film formation was performed in an Ar atmosphere of 0.9 Pa after evacuating the chamber to 1.0 × 10 ⁻⁴ Pa or less. The sputtering power was 350 W and the film thickness was 50 to 500 nm. For the obtained film, measure the film thickness with a surface roughness meter, further measure the sheet resistance using a four-probe low resistivity meter Loresta IP (Mitsubishi Chemical), and multiply the film thickness by the sheet resistance. The volume resistivity was calculated. Moreover, resistance measurement was performed while heating up in a thermostat, and the temperature coefficient of resistance at −25 to 125 ° C. was obtained. The results are shown in Table 3.

  The volume resistivity and temperature coefficient of resistance of the manufactured thin film resistor almost reflected the characteristics of the bulk sample shown in Table 2. As in the case of the bulk samples of Examples 1 to 3, Examples 1 to 4 of the present invention have a volume resistivity several times that of the Ni—Cr alloy of Conventional Example 1, and according to the present invention, an equivalent resistance temperature coefficient is obtained. It can be seen that a thin film resistor showing

(Examples 5-7)
Next, using the sputtering target of Example 1, the ultimate vacuum at the time of sputtering was changed to form a film on a glass substrate. About the obtained film | membrane, the film thickness was measured with the surface roughness meter, the sheet resistance was measured by the four-probe method, and the volume resistivity was calculated by multiplying the film thickness and the sheet resistance. Moreover, resistance measurement was performed while heating up in a thermostat, and the temperature coefficient of resistance at −25 to 100 ° C. was obtained. The results are shown in Table 4.

It can be seen that when the ultimate vacuum is lower than 1.0 × 10 ⁻⁴ Pa, the volume resistivity of the thin film resistor is extremely lower than that of the bulk sample shown in Table 2.

(Examples 8 and 9, Comparative Example 7, Conventional Examples 2 and 3)
In order to compare the thermal stability and reliability of the thin film resistors, the sputtering targets of Examples 1 and 2 and Comparative Example 1 and a conventional example of Ni—Cr alloy were used, and 10 mm wide on a quartz glass substrate by a metal mask. After the film formation, a metal mask was applied again, and gold was formed on both ends to form a resistance pattern having a width of 10 mm and a length of 50 mm as an electrode. About the obtained film | membrane, the film thickness was measured with the surface roughness meter, and the resistance value of the resistance pattern was measured with the four-terminal method. Furthermore, it hold | maintained at 155 degreeC for 500 hours in the thermostat, and the resistance change by heating was measured. The results are shown in Table 5.

  The resistance change due to heating in a pattern with a film thickness of 200 nm was comparatively investigated for the example of the present invention, the comparative example, and the conventional example. When the resistance change after heating was compared, in Comparative Example 7 in which the amount of Cr added was small, the resistance change was several tens of times larger than in the example of the present invention.

  It can be seen that the rate of change of Examples 8 and 9 of the present invention is almost the same as that of Conventional Examples 2 and 3. However, at the same film thickness, the Ni—Cr alloy has a low volume resistivity and therefore has a resistance value of about ¼. Therefore, when compared with the same resistance value, it is found that the film thickness must be reduced to 50 nm, and the resistance change rate at that time is nearly twice as high.

  As described above, according to the present invention, a material suitable for a high-resistance metal thin film resistor can be obtained which is superior in thermal stability as compared with a conventional Ni—Cr alloy.

Claims (4)

V: 10 to 15% by mass, Al: 12 to 16% by mass, Cr: 1 to 30% by mass, the balance being substantially composed of Fe, absolute value of resistance temperature coefficient at −25 to 125 ° C. Is 200 ppm / ° C. or less and has a volume resistivity of 400 μΩcm or more. 2. A metal resistor according to claim 1 in the form of a thin film. The metal resistor according to claim 1, comprising: V: 10 to 15% by mass, Al: 12 to 16% by mass, Cr: 1 to 30% by mass, and the balance being substantially made of Fe. Sputtering target to do. The sputtering target according to claim 3 is used, and at the time of sputtering, the inside of the chamber is evacuated to 1.0 × 10 ⁻⁴ Pa or less, and then sputtering is performed in an Ar atmosphere, and the metal resistor according to claim 1 is formed into a thin film A method for producing a metal resistor, characterized by comprising: