JP4752075B2 - Resistor and its manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thin film resistor forming the thin film resistor such as by vapor deposition or sputtering on the surface of the insulating substrate. Further it relates to the production how this resistor.
[0002]
[Prior art]
A thin film resistor is known in which a thin film resistor is formed by vapor deposition or sputtering of a thin film resistor material on an insulating substrate such as glass or alumina, and a pattern is formed on the thin film resistor by photoetching or laser processing. Oh Ru.
[0003]
In this type of resistor, it is necessary that the resistance value be stable over as wide a temperature range as possible, and a temperature coefficient of resistance (hereinafter referred to as TCR) is used to indicate this stability. Here, TCR is defined by the following equation, for example, when 25 ° C. is a reference temperature, a resistance value at this temperature is R (25), and a resistance value at temperature t is R (t).
TCR (ppm / ° C.) = {R (t) −R (25)} / R (25)
× [1 / (t−25)] × 10 ⁶
[0004]
When making a resistance thin film or a metal foil, it is generally desired to make this temperature coefficient of resistance TCR zero. For this reason, it is usual to study by changing various deposition conditions and sputtering conditions, or changing the thickness and type of substrate. As the thin film resistor, one using Ta (tantalum) is known as one of the most stable resistors at present. In addition, it has been conventionally performed to add T1 to zero by adding Al (aluminum) or Si (silicon) to a Ni-Cr (nickel-chrome) alloy.
[0005]
[Problems of conventional technology]
However, because of the non-linearity of the resistance value temperature change, it has been difficult for the conventional resistor to make the TCR minute or close to zero in a wide temperature range.
[0006]
OBJECT OF THE INVENTION
This invention is made | formed in view of such a situation, and makes it the 1st objective to provide the resistor which can make resistance temperature coefficient TCR approach zero in a wide temperature range. Also to provide a method of manufacturing the resistor and the second object.
[0007]
[Structure of the invention]
According to the present invention, a first object is to provide a resistor having a resistor on the surface of an insulating substrate.
The resistor has a Ni—Cr composition ratio of Ni / Cr of 83/17 to 60/40, an Al content of 3 to 10 at% , and an Mn content of 3 to 10 at%. Ri thin film resistor der of an alloy, the temperature coefficient of resistance TCR is a resistor, characterized in der Rukoto within ± 2 ppm / ° C., it is achieved by.
[0008]
Here, the Al (aluminum) content is 3 to 10 at%, and the Mn (manganese) content is 3 to 10 at%. Here, “at%” is an atomic percent of the atomic ratio and is synonymous with “mol%”.
[0009]
As the insulating substrate, glass, alumina, calcium titanate, sapphire, and the like are suitable. Resistor Ru can be a thin film resistor formed by vapor deposition or sputtering.
[0010]
The second object is a method of manufacturing a resistor according to claim 1 , wherein the thin film resistor is formed on the surface of the substrate by vapor deposition or sputtering, while the thin film resistor is being formed or during at least one step after the formation. This is achieved by a method for manufacturing a resistor, characterized by performing a heat treatment in a vacuum . In this case, a thin film containing Mn and a thin film containing Al can be formed by being overlapped and integrated to form a thin film resistor.
[0014]
Embodiment
A thin film resistor in which Al and Mn were added to a Ni—Cr alloy was formed by radio frequency (RF) sputtering. The atmosphere at this time was an Ar (argon) gas pressure of 0.5 Pa, the insulating substrate was alumina, the RF power was 300 W, and the thin film thickness was 0.3 μm. The composition ratio Ni / Cr (at%) of the Ni—Cr alloy is 77/23, and the addition amounts of Al and Mn are 9.5 at% and 5 at%. The heat treatment is performed by leaving the resistor at 300 ° C. or higher, preferably about 500 ° C. for about 3 hours in a vacuum.
[0015]
FIG. 1 is a graph showing the results. For comparison, the results for the case where Mn is not added are also shown. That is, in this comparative example, 12 at% Al is added to a Ni—Cr alloy having a composition ratio Ni / Cr (at%) of 80/20. Other conditions such as atmosphere, substrate material, and heat treatment in this case were the same as in the above embodiment. As apparent from FIG. 1, according to the embodiment of the present invention, the resistance value change rate (R (t) −R (25)) / R (25) becomes extremely small over a wide temperature range. There was found.
[0016]
Moreover, FIG. 2 shows the result measured about an example of what is marketed conventionally. In addition, the component of this product seems to have added Si to the Ni-Cr alloy, and other conditions, such as heat processing, are unknown. As is clear from a comparison between FIG. 2 and FIG. 1, it has become clear that the TCR can be reduced over a wide temperature range according to the present invention.
[0017]
The inventor analyzed the influence of the added element on the TCR when the Ni—Cr alloy was used as the base alloy. That is, the resistance value change rate (R (t) −R (25)) / R (25) is approximated by the following quadratic equation, and the primary temperature coefficient α (ppm / ° C.) and the secondary temperature coefficient β (ppm / ° C.). Elements that mainly contribute to ² ) were selected. [R (t) −R (25)] / R (25) = α (Δt) + β (Δt) ²
However, Δt = t−25
[0018]
It was found that Al, Si, Be, Mg, Ti, and Mn are elements that mainly contribute to the primary temperature coefficient α (referred to as the first group). Further, it was found that there are Mn, Fe, Co, Ti, and V as elements mainly contributing to the secondary temperature coefficient β (referred to as the second group). Mn and Ti are included in both groups because these are effective for both α and β.
[0019]
The inventor first selected Al as the element of the first group, and obtained the optimum addition amount of Al for sufficiently reducing the primary coefficient α. For this reason, a large number of resistors with different amounts of Al are manufactured, and among them, the coefficient α is sufficiently small and the rate of change in resistance value is 10 at as an optimum amount to bring it close to zero over a wide temperature range. %. FIG. 3 is a diagram showing the effect of the addition of Al on the resistance value change rate. FIG. 3 shows a comparative example in which the composition ratio Ni / Cr (at%) is 77/23 and no Al is added. The thin film formation conditions here are the same as in the case of FIG.
[0020]
Next, Mn selected from the second group was further added to this Ni—Cr alloy with 10 at% added Al, and the optimum addition amount for reducing the secondary coefficient β was determined. FIG. 4 is a diagram showing the influence of the addition of Mn on the resistance value change rate. In FIG. 4, the vertical scale of FIG. 3 is enlarged about 15 times.
[0021]
FIG. 4 shows three measurement examples A, B, and C in which the amount of Mn added is 0, 10, and 5 at% to a Ni—Cr alloy containing 10 at% Al. That is, A does not contain Mn and is the same as that shown in FIG. B is obtained by adding 10 at% of Mn, and the rate of change in resistance value is greatly bent contrary to the case of A, so that it is understood that the amount of Mn added is too large. C is an intermediate addition amount between A and B, that is, Mn is 5 at%. From this result, it was found that TCR is within ± 2 ppm / ° C. That is, it was found that the optimum amount of Mn was 5 at%.
[0022]
The resistors used for these measurements are manufactured under the same conditions as the thin film resistors used in FIG. 1 and 2 show a primary coefficient α and a secondary coefficient β obtained for each resistor. Comparing these coefficients α and β, α and β of the resistor according to the present invention shown in FIG. 1 are remarkably smaller than those of the other (comparative example) and (conventional product) resistors. It can also be seen that it approaches zero over a very wide temperature range.
[0023]
The elements of the first group and the second group can be determined as follows, for example. FIG. 5 shows the formation of thin films obtained by adding 10 at% each of Al, Si, Mn, and Fe to an alloy having a composition ratio Ni / Cr of 77/23 (at%), and the primary temperature coefficient for each thin film. It is the figure which calculated | required (alpha). FIG. 6 is a diagram in which the secondary temperature coefficient β is similarly obtained.
[0024]
From FIG. 5, α is about +55 ppm / ° C. for Ni—Cr alloy alone, whereas it is about −70 for Al added at 10 at% and about 0 for Si added at 10 at%. It can be seen that Al is suitable for improving the coefficient α.
[0025]
Similarly, from FIG. 6, β is about −0.04 (ppm / ° C. ² ) in the Ni—Cr alloy, whereas β is +0.03 in the case where Mn and Fe are added. It can be seen that Fe is suitable for improving the secondary coefficient β. The elements of the first group and the second group are obtained by conducting the above experiment on various elements. The resistors used in FIGS. 5 and 6 are thin film resistors manufactured under the same conditions as those in FIG.
[0027]
【The invention's effect】
As described above, the composition ratio Ni / Cr of the Ni / Cr alloy is 83/17 to 60/40 , the Al content is 3 to 10 at% , and the Mn content is 3 to 3 . It is a thin film resistor made of a Ni / Cr alloy of 10 at% , and the resistance temperature coefficient TCR is within ± 2 ppm / ° C., so that it can approach zero over a wide temperature range.
[0029]
This resistor is a thin film resistor formed by vapor deposition or sputtering, the stability of the resistance value can be further improved by applying a vacuum during heat treatment in at least one of the steps after the formation during and formation ( Claim 2 ). In the vapor deposition or sputtering, it is a matter of course that the resistor may be formed by a single treatment, but thin films having different components may be formed by being divided into a plurality of times (claim 3 ).
[Brief description of the drawings]
FIG. 1 is a diagram showing a resistance value change rate of an embodiment of the present invention. FIG. 2 is a diagram showing a resistance value change rate of a conventional product. FIG. 3 is a diagram showing a contribution of Al added to a Ni—Cr alloy. FIG. 4 shows the contribution of Mn added to Ni / Cr · Al. FIG. 5 shows the contribution of the first element to the coefficient α. FIG. 6 shows the contribution of the second element to the coefficient β. Figure

Claims (3)

In a resistor having a resistor on the surface of an insulating substrate,
The resistor has a Ni / Cr composition ratio of Ni / Cr of 83/17 to 60/40, an Al content of 3 to 10 at% , and a Mn content of 3 to 10 at%. Ri thin film resistor der of an alloy, resistor temperature coefficient of resistance TCR is characterized der Rukoto within ± 2 ppm / ° C..   2. The method of manufacturing a resistor according to claim 1, wherein the thin film resistor is formed on the surface of the substrate by vapor deposition or sputtering, and heat treatment in vacuum is performed during the formation of the thin film resistor and at least one step after the formation. A method for manufacturing a resistor. 3. The method of manufacturing a resistor according to claim 2 , wherein the thin film resistor is formed by forming a Ni-Cr alloy thin film containing Mn and a Ni-Cr alloy thin film containing Al on top of each other.

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