JPH10270201A - Cr-n-based strained resistance film, manufacture therefor and strain sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly stable high-sensitivity thin film for strain sensor by reducing the absolute value of the resistance-temperature coefficient of a Cr thin film, while maintaining the gage factor of the Cr thin film as much as possible. SOLUTION: This resistance film is set to be composed of a thin film, a having a composition expressed by a general formula Cr100-x-y Nx My , where M represents one or two or more kinds of elements selected form among Ti, V, Nb, Ta, Ni, Zr, Hf, Si, Ge, C, O, P, Se, Te, Zn, Cu, Bi, Fe, Mo, W, As, Sn, Sb, Pb, B, Ga, In, Tl, Ru, Rh, Re, Os, Ir, Pt, Pd, Ag, Au, Co, Be, Mg, Ca, Sr, Ba, Mn, Al, and rare-earth elements and x and y are atomic percentages specified satisfying relations of 0.0001<=x<=30 and 0<=y<=30, and 0.0001<=x+y<=500, a crystal structure composed mainly of the bcc structure or a mixed structure of the bcc structure and A15-type structure, a gage factor of >=2, and temperature coefficient of an electric-resistance -4×10<-4> to 4×10<-4> / deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to Cr (chromium) and N (nitrogen) as main components and Ti (titanium), V (vanadium), Nb (niobium), Ta (tantalum), Ni ( Nickel), Zr (zirconium), H
f (hafnium), Si (silicon), Ge (germanium), C (carbon), O (oxygen), P (phosphorus), Se (selenium), Te (tellurium), Zn (zinc), Cu (copper),
Bi (bismuth), Fe (iron), Mo (molybdenum),
W (tungsten), As (arsenic), Sn (tin), S
b (antimony), Pb (lead), B (boron), Ga
(Gallium), In (indium), Tl (thallium), Ru (ruthenium), Rh (rhodium), Re
(Rhenium), Os (osmium), Ir (iridium), pt (platinum), Pd (palladium), Ag
(Silver), Au (gold), Co (cobalt), Be (beryllium), Mg (magnesium), Ca (calcium),
Sr (strontium), Ba (barium), Mn (manganese), Al (aluminum) and one or more of rare earth elements in total 0.0001 to 50%
The present invention relates to a Cr _— N-based strain (strain) resistive film, a method for manufacturing the same, and a strain sensor (also referred to as a strain gauge) using the resistive film. 2 or more, and the temperature coefficient of resistance _(- 4 to 4) to provide a strain resistance film is within × ^{10 -4} / ℃. Another object of the present invention is to provide a strain sensor including the strain resistance film.

[0002]

2. Description of the Related Art A strain sensor generally utilizes a phenomenon in which the electrical resistance of a thin wire or foil-shaped sensor material changes depending on elasticity. However, a strain sensor measures a change in resistance to measure strain or stress. And used for conversion. For example, strain gauges, weigh scales, accelerometers, torque meters, flow meters and various mechanical-electricity converters in the production industry, earth pressure gauges in the civil engineering industry, pressure gauges, flow meters and deflections in the construction and energy related industries Meters, accelerometers, torque meters, flow meters, and various stress / strain meters in the aviation, space, railway, and ship-related industries, and are also widely used in commercial scales and security equipment for consumer use. ing.

The strain sensor has a thin metal wire (10 to 10).
30 μm) or a metal foil (3 to 5 μm) is arranged in a grid or rosette shape. The sensor material is attached to an object to be measured with an adhesive, and a strain generated in the object to be measured is obtained. Is indirectly measured from a change in resistance of the sensor. The sensitivity of the strain sensor is determined by the gauge factor K, and the value of K is generally given by the following equation.

[0004]

(Equation 1)

[0005] Here, R, σ, ρ and l are the total resistance, Poisson's ratio, specific electrical resistance and total length of the thin wire or foil as the sensor material, respectively. In general, since σ in a metal or alloy is approximately 0.3,
The sum of the term and the second term is approximately 1.6, which is a substantially constant value. Therefore, in order to increase the gauge factor, it is an essential condition that the third term in the above equation is large. That is,
This is because when the material is subjected to tensile deformation, the electronic structure in the longitudinal direction of the material changes significantly, and the variation Δρ / ρ in the specific electrical resistance increases.

[0006] Materials having a large gauge factor include semiconductor carbon,
Silicon and germanium are known. However, in the case of these semiconductors, the gauge factor is as large as 10 to 170, but the anisotropy of the value and the fluctuation due to temperature are large and lack stability, and furthermore, there are drawbacks such as poor mechanical strength. It is only applied to special small pressure transducers. The most frequently used material for the strain sensor at present is a Cu _- Ni alloy. Since this alloy has a very small temperature coefficient of resistance, it has the characteristic that the characteristics change with temperature change is small, but on the other hand, the gauge factor is as small as 2 and it is suitable as a material for high-sensitivity strain sensors. Absent.

[0007] Strain sensors using alloy bulk materials are used in the form of fine wires or foils as described above. However, thin wire strain sensors have large variations in characteristics due to the effects of residual strain during grid formation and the effect of an adhesive used to adhere the processed thin wire to the substrate. Since special techniques such as bonding of substrates are required, the production efficiency is low, which causes high costs. The foil-shaped strain sensor is not affected by strain during processing, but the effect of the adhesive is the same as that of the thin wire, which is also a problem.

[0008]

The area of application of strain sensors has been expanding with the recent advances in microcomputers, and has been directed toward miniaturization and higher performance.
This applies to any of the applications described in the “Prior Art” section, but in particular, strain transducers that can be used for pressure sensors and load cells that require high sensitivity and stability, as well as robot contact sensors and slip sensors, etc. The demand for sensors has increased. With respect to strain sensors used for these various sensors, there is an urgent need to develop a material having high sensitivity and good stability and to improve the manufacturing process.

It is an object of the present invention is to solve is already greater than the gauge factor 2 of strain sensors that are commercially available, and practical ^{_{(- 4~4) × 10 -4 /}} ℃ are within desirable resistance The aim is to develop a thin film material with a small temperature coefficient and a manufacturing method thereof. In the present invention, the object is narrowed down to a structurally stable metal material as a material having high sensitivity and good stability, and Cr is focused on as a material having a high gauge factor.

It is known that the bulk (lumped) resistance strain sensitivity of Cr is as large as 26 to 28. However, since Cr is extremely difficult to process, it has not been possible to use it for thin wire and foil-shaped strain sensors. Therefore, it is conceivable to apply Cr to a strain sensor by thinning without requiring processing. The gauge factor of the Cr thin film is as large as about 15, though not as large as the bulk. Further, since the material is directly applied to the substrate, the problem of the influence of the adhesive which occurs in the case of the strain sensor using the alloy bulk material is also solved. On the other hand, the strain sensor must not be sensitive to physical quantities other than strain, and in particular, the amount of change in electrical resistance with respect to temperature must be small. However, as shown in FIG. 1, the temperature dependence of the resistance of a Cr thin film produced using a normal vapor deposition apparatus or a sputtering apparatus indicates that the resistance to temperature near a normally used room temperature (here, the resistance value at 0 ° C. big change of which) using the resistance value R / R 0 _{° C.} the vertical axis normalized is, a large value that the TCR negative _(- 6 × 10
⁻⁴ / ° C.), which is not suitable for a strain sensor in terms of stability.

The present invention has been made to provide a highly sensitive and stable thin film for a strain sensor by reducing the absolute value of the temperature coefficient of resistance while maintaining a high gauge factor of a Cr thin film as much as possible. Things.

[0012]

As a result of a number of experiments on the preparation of a Cr thin film, a bulk Cr of about 30 × 10 ⁻⁴ / ° C. was obtained.
TCR is about the thinning of _- a cause of a 6 × 10 -4 ^/ ℃, vacuum degree in the deposition chamber in the thin film produced immediately before it was revealed that relate. That is, the film forming chamber background vacuum degree conventional deposition apparatus or a sputtering apparatus is about 10 - is a ₇ order, TCR changes from positive to negative by changing the amount of air very slightly present in the vacuum It is. Since the main component of air is nitrogen, as a result of intentionally adding it to the Cr thin film,
It has been found that CR can take a negative value, and that the value of TCR differs depending on the nitrogen concentration. FIG. 2 shows the relationship between nitrogen concentration and TCR. As a result of examining the crystal structure of the film to which 20% or less of nitrogen was added, they were found to have a bcc structure of Cr or an A15 type structure (reference document) or a mixed structure of both. If the nitrogen concentration is low,
The crystal structure becomes a bcc structure and the TCR shows a positive value. On the other hand, if the crystal structure is large, the crystal structure becomes an A15 type structure and the TCR becomes
Indicates a negative value.

Further, as in the case of the Cr ₉₆ N ₄ strain resistance film shown in FIG. 3, it has been found that the TCR of these thin films increases as the heat treatment temperature increases and is determined by the heat treatment temperature. That is, a thin film exhibiting a negative TCR is heat-treated at an appropriate temperature during film formation, so that a TCR of about 0 × 10 ⁻⁴ /
Thus, a thin film having a characteristic of ° C. can be obtained. At this time, as in the case of the Cr ₉₆ N ₄ strain resistance film shown in FIG.
It changes to a cc structure, but in this process, bc
In a heat treatment temperature region where the structure in which the c structure and the A15 type structure coexist is changed to the structure of the bcc structure alone, a value near zero is obtained as the TCR. According to these production methods, the composition is represented by the general formula Cr _100-x N _x , and the composition ratio x has a relation of 0.0001 ≦ x ≦ 30 in atomic%, and the crystal structure has a bcc structure or mainly a bcc structure. A15
It consists mixed structure of the mold structure, a gauge index of at least 2, and the temperature coefficient of electrical resistance _{(- 4} ~ 4) Cr, characterized in that within _× 10 -4 ^/ ℃ - _N Motoibitsu resistive film Was obtained and found to be suitable as a material for a high-sensitivity strain sensor.

By using a Cr _— N strain-resistant material, a TCR of about 0 × 10 ⁻⁴ / ° C. can be obtained, but the temperature range where the TCR shows about 0 × 10 ⁻⁴ / ° C. It does not always match the operating temperature range. Therefore, it was considered that the addition of an auxiliary component was effective in making them match. It is known that the temperature of the Neel point (Neel temperature) of bulk Cr shifts to a lower temperature side or a higher temperature side by adding a specific element. Therefore, the resistance temperature curve showing the temperature dependence of the resistance value is considered to be closely related to the Neel point, and various elements are added to Cr _- N as subcomponents, and the added amount and the resistance temperature curve are compared. An experiment for investigating the relationship with the movement width was conducted enthusiastically. As a result, it is possible to move the resistance temperature curve along the temperature axis by adding an appropriate amount of the subcomponent element to Cr _- N, thereby reducing the portion of the resistance temperature curve where the variation is small to the operating temperature. It has been found that it can be moved within the range.

Further, even when the strain sensor is used at a temperature other than room temperature, the strain resistance having a small temperature coefficient of resistance in a desired temperature range can be obtained by appropriately selecting the type and amount of the element added to Cr _- N. A film was obtained, and it was found that it was possible to provide a strain sensor using the film.

[0016] Based on these findings, further result of numerous experiments, is represented by the general formula _{Cr 100-x-y N x} M y, M is Ti, V, Nb, Ta, Ni, Zr, Hf,
Si, Ge, C, O, P, Se, Te, Zn, Cu, B
i, Fe, Mo, W, As, Sn, Sb, Pb, B, G
a, In, Tl, Ru, Rh, Re, Os, Ir, P
t, Pd, Ag, Au, Co, Be, Mg, Ca, S
r, Ba, Mn, Al and one or more elements selected from rare earth elements, and the composition ratios x and y are 0.0001 ≦ x ≦ 30, 0 ≦ y ≦ 30, 0. 00
Has 01 ≦ x + y ≦ 50 the relationship, the crystal structure is mainly bcc structure or mainly mixed structure of bcc structure and the A15 type structure, a gauge index of at least 2, and the temperature coefficient of electrical resistance _{(- 4 ~} 4) It was found that a Cr _— N-based strain resistance film having a temperature within _× 10 ⁻⁴ / ° C. was obtained and was suitable as a material for a high-sensitivity strain sensor.

In order to manufacture the present invention, a vapor deposition method using an alloy having the above composition as a raw material, a sputtering method using an alloy target, a composite target or a multi-target capable of forming a thin film having the above composition, An insulator film is formed on an insulating substrate or a conductive substrate surface by a reactive sputtering method using a film formation atmosphere containing a gas, or a vapor phase transport method using a material capable of forming a thin film having the above composition. Then, a thin film having a desired shape and thickness is formed by using a mask method or the like. Alternatively, after forming a thin film of an appropriate shape, dry etching (plasma etching, sputter etching, etc.), chemical etching (corrosion method), lift-off method, etching such as laser trimming or trimming is performed to obtain a desired shape. Process to form an element. If necessary, as a temperature compensation, a gauge pattern in which elements arranged at right angles to the above elements are constructed within the same value is formed. Further, the electrode may be used as it is, or an electrode may be formed on the electrode if necessary, and if necessary, these thin films may be formed in the air, in a non-oxidizing gas, in a reducing gas or in a vacuum at a temperature of 200 ° C. After heating at a temperature for an appropriate time, preferably from 1 second to 100 hours, and then cooling at an appropriate rate, preferably from 1 ° C./hour to 100 ° C./minute, the resistance strain sensitivity (gauge rate) There at least two, and temperature coefficient of resistance _{(- 4~4)} × ^{10 -4} / strain sensor Cr has a value of less ° C. _- N group thin film is obtained.

First Invention Se, Te, Zn, Cu, Bi, Fe, Mo, W, A
s, Sn, Sb, Pb, B, Ga, In, Tl, Ru,
Rh, Re, Os, Ir, Pt, Pd, Ag, Au, C
o, Be, Mg, Ca, Sr, Ba, Mn, Al and one or more elements selected from rare earth elements, and the composition ratio x, y is 0.0001 ≦ x ≦ 3 in atomic%.
0, 0 ≦ y ≦ 30, 0.0001 ≦ x + y ≦ 50, and the crystal structure is mainly a bcc structure or a mixed structure of mainly a bcc structure and an A15 type structure,
A gauge factor of 2 or more, and the temperature coefficient of electrical resistance _(- 4
N Motoibitsu Resistive _- Cr, characterized in that _1-4) is within _× 10 ^-4 10 / ℃.

[0019] in a gas atmosphere containing a second invention of nitrogen, by vapor deposition or sputtering, is represented by the general formula _{Cr 100-x-y N x} M y, M is Ti, V, Nb, Ta, Ni, Zr , Hf, S
i, Ge, C, O, P, Se, Te, Zn, Cu, B
i, Fe, Mo, W, As, Sn, Sb, Pb, B, G
a, In, Tl, Ru, Rh, Re, Os, Ir, P
t, Pd, Ag, Au, Co, Be, Mg, Ca, S
r, Ba, Mn, Al and one or more elements selected from rare earth elements, and the composition ratio x, y is 0.0001 ≦ x ≦ 30, 0 ≦ y ≦ 30, 0.0001 in atomic%.
≦ x + y ≦ 50, and the crystal structure is mainly b
A Cr _— N-based strain resistive film having a cc structure or a mixed structure of mainly a bcc structure and an Al5 type structure is formed on an insulating substrate, or an insulating film is formed on a conductive base plate. Then, the strain resistance film is formed at a temperature of 200 ° C. or higher for 1
Cr heat-treated at a temperature of 000 ° C. or less
_- preparation of N Motoibitsu resistive film.

Third invention A strain sensor using the Cr _— N based strain resistance film according to the first invention.

[0021]

The TCR value of the Cr _- N thin film differs depending on the nitrogen concentration. When the nitrogen concentration is low, the crystal structure becomes a bcc structure and the TCR shows a positive value. When the nitrogen concentration is high, the crystal structure becomes mainly an A15 type structure. TCR showed a negative value. Further, as shown in FIG. 3, it has been found that the TCR of these thin films increases with an increase in the heat treatment temperature and strongly depends on the heat treatment temperature. Therefore, it is considered that an excellent Cr _- N strain resistance film having zero TCR characteristics can be obtained by heat-treating a thin film having a negative TCR formed in an atmosphere gas containing an appropriate amount of nitrogen at an appropriate temperature. Can be
The crystal structure of the film at this time is, as shown in FIG.
The structure changes from a mold structure to a bcc structure with an increase in heat treatment temperature. In this process, the bcc structure and A15
The TCR takes a value near zero in a temperature region where the structure in which the type structure coexists is changed to the structure of the bcc structure alone.

If the nitrogen concentration is greater than about 15%,
Cr nitride microcrystal or amorphous state of (Cr ₂ N and CrN, etc.) _CrN is generated in the film of Cr to Cr or bcc structure and A15 type structure of bcc structure coexist, crystal structure is hard to determine May be. In such a case as well, the TCR shows a negative value, but the TCR can be controlled by heat treatment and can be reduced.
However, as the proportion of Cr _- N in the microcrystalline or amorphous state of these Cr nitrides increases, TC
R increases, and if it exceeds 30%, almost the entire film becomes Cr nitride and the TCR exceeds 4 × 10 ⁻⁴ / ° C., which is not preferable. Therefore, the nitrogen concentration was limited to 30% or less.

The solid line in FIG. 5 represents Cr heat-treated at 500 ° C.
₄ shows a resistance temperature curve of a ₉₆ N ₄ strain resistance film. About _- 80 in a temperature range of + 150 ℃ from ° C. the slope of the curve is small, that is, the temperature change is small, shows excellent properties as a strain sensor used in this temperature range. In fact, the TCR calculated from the slope of this curve was a small value within ± 1 × 10 ⁻⁴ / ° C. Here, if the temperature range to be used is little hot, approximately the TCR is small _- 80 ° C.
To + 150 ° C. to its desired temperature range. As a means for achieving this, it is considered effective to add an appropriate amount of subcomponent elements to Cr _- N. The dashed dotted line and the dashed line in FIG. 5 indicate Cr ₉₆ N ₄ to which Mn was added at 1%, 2% and 3%, respectively.
_{96-y N 4 Mn y (} y = 1,2 and 3) showing the resistance-temperature curve of the thin film. From the figure, it can be seen that the resistance temperature curve shifts to the higher temperature side as the Mn content increases. As described above, by adding the subcomponent element, the resistance temperature curve can be moved along the temperature axis, and the region where the change in the resistance temperature curve is small can be moved to the operating temperature range. At this time, it is necessary to selectively use an element having a function of moving the resistance temperature curve to a low temperature side and an element having a function of moving the resistance temperature curve to a high temperature side.

FIGS. 6 to 13 show Cr _{100-xy formed} on a glass substrate using a high frequency sputtering apparatus.
For N _x M _y samples, the amount y of each sub-component element M,
Temperature coefficient of resistance at 0-50 ° C and room temperature (about 20
C)). As can be seen from these figures, Ti, V, Nb, Ta, Ni, Zr, H
f, Si, Ge, C, O, P, Se, Te, Zn, C
u, Bi, Fe, Mo, W, As, Sn, Sb, Pb,
B, Ga, In, Tl, Ru, Rh, Re, Os, I
r, Pt, Pd, Ag, Au, Co, Be, Mg, C
a, Sr, Ba, Mn, Al and one or more of the rare earth elements of 30% or less, respectively, and a total of 0.0001 to 50%, preferably 0.1 to 50%, including nitrogen.
1 to 40%, more preferably 1 to 40% and the balance C
reason for limiting the r is the gauge factor in these ranges is more than one higher value is obtained, and the temperature coefficient of resistance _(- 4 to 4)
This is because a small value within × 10 ⁻⁴ / ° C. is obtained,
Outside of these ranges, these effects cannot be expected.

Of the above subcomponents, Hf, Zr, P, A
s, Sb, Mg, Ca, Co and Pd are also beyond the scope of limiting the resistance temperature coefficient ^{_{(- 4~4) × 10 -4 /}} ℃
However, if it exceeds 30%, the gauge factor becomes smaller than 2, so that it cannot be applied to a strain gauge, and therefore, the above-mentioned limitation is applied to these elements.

From FIGS. 2 to 7, it can be seen that the gauge factor decreases with an increase in the added amount of the auxiliary component.
e, Al and Ga show a small decrease in the gauge factor with an increase in the addition amount of the subcomponent, and also show Ni, Nb and Ti
Since the minimum point moves to around room temperature only by adding a small amount of these subcomponents, a high gauge factor can be obtained.
A high gage factor is obtained when a plurality of elements capable of obtaining these high gage factors are added, and a gage factor value larger than 2 is obtained when two or more of the subcomponents of the present invention are added. was gotten.

The rare earth elements are Sc, Y and lanthanum elements (La, Ce, Pr, Nd, Pm, Sm, E
u, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), but their effects are equal and all are the same active ingredients.

FIG. 14 shows the relationship between the heating temperature and the temperature coefficient of resistance, the specific resistance and the gauge factor of the alloy of the present invention (Sample No. 13). As can be seen, the alloy of the present invention was
In a temperature range of not less than 1000 ° C. and not more than 1 minute and not more than 100 hours, and then not less than 1 ° C./hour and not more than 1000 ° C.
By cooling at a rate of not more than / min, desired gauge characteristics can be obtained. 200 ° C or higher 1 under heat treatment conditions
In 000 ° C. below the temperature range, preferably reason for limiting to heat to 100 hours or more per minute, a gauge rate in this process condition 2 or more and the temperature coefficient of resistance _(- 4~4) × 10 ^-4 / ° C. If the temperature is lower than 200 ° C., a stable TCR cannot be obtained, which is not preferable. If the temperature is higher than 1000 ° C., a desired TCR cannot be obtained, which is not preferable.

[0029]

An embodiment of the present invention will be described. Example 1 Production and Evaluation of Alloy Thin Film of Sample No. 1 (Composition: Cr _- 4% N) A Cr disk having a diameter of 105 mm and a thickness of 3 mm (purity 9)
(9.9%) to a copper electrode to form a sputtering target. A small amount of nitrogen gas flows along with Ar (argon) as a sputtering gas as a film forming atmosphere,
From this target, a Cr _— N thin film having a thickness of about 0.36 μm is produced using a magnetron-type high-frequency sputtering apparatus under the following sputtering conditions (reactive sputtering). The substrate is covered with a glass mask before film formation so that a patterned thin film can be formed during film formation. Preliminary evacuation 1 × 10 ⁻⁷ Torr High frequency power 100 W Argon flow rate 20.0 SCCM Nitrogen flow rate 0.9 SCCM Atmospheric gas pressure 1 × 10 ⁻² Torr Substrate glass (CORNING # 0211) Substrate warming Non-heating Distance between electrodes 50 mm Film forming speed 30 mm A coated wire having a diameter of 0.05 mm was welded to the prepared thin film using solder to form an electrode, and the temperature coefficient of resistance and the gauge factor were measured by a four-terminal method. As a result, as shown in Table ^{_{1, - 6 × 10 -4 /}} ℃ negative resistance-temperature coefficient and 7.1 gauge factor was obtained. Next, the obtained thin film is heated in various atmospheres at various temperatures of 200 ° C. to 1000 ° C. for an appropriate time and then cooled in a furnace to room temperature (cooling rate: 200 ° C./hour).
did. Table 1 shows the heat treatment conditions and the measured gauge factor, specific resistance, and temperature coefficient of resistance (TCR). In any atmosphere, the gauge factor was improved and showed a large value. The temperature coefficient of resistance increases as the temperature of the heat treatment increases.
Very excellent characteristics of 4 × 10 ⁻⁴ / ° C. and a gauge factor of 7.4 were obtained.

[0030]

[Table 1]

Example 2 Sample No. 14 (Composition: Cr _- 4
% N _- 6.0% V) Production and evaluation of alloy thin film Purity 9
9.9% of Cr and V are alloyed by an arc melt method to produce an alloy target having a diameter of 203 mm and a thickness of 5 mm. The alloy target is bonded to a copper electrode to form a sputtering target. From this target, a thin film having a thickness of 0.36 μm is produced using an ion beam sputtering apparatus under the sputtering conditions shown below. The substrate is covered with a glass mask before film formation so that a gauge pattern can be formed at the time of film formation, and a stacked electrode of Ni and Au is constructed. Preliminary evacuation 2 × 10 ⁻⁸ Torr Acceleration voltage 700 V Ion current density ² mA / cm ² Nitrogen gas flow 0.5 SCCM Nitrogen gas pressure 0.5 mtorr Substrate Stainless steel with SiO ₂ insulating film formed on the surface Substrate temperature 500 ° C. Between ion source and target Distance 120 mm Substrate-target distance 120 mm Deposition rate 90 ° / min An Au wire was welded to the electrode of the prepared thin film, and the resistance temperature coefficient and the gauge factor were measured by a four-terminal method. A value of ⁻⁴ / ° C. and 9.4 was obtained.
Next, the obtained thin film is applied at 200 ° C. to 1000
After heating at various temperatures of ° C. for an appropriate time, it was cooled in a furnace to room temperature (cooling rate: 500 ° C./hour). Table 2 shows the heat treatment conditions and the measured gauge factor, specific resistance, and temperature coefficient of resistance (TCR). In any atmosphere, the gauge factor increased with the temperature. FIG. 14 shows the relationship between the heat treatment temperature, the temperature coefficient of resistance, the specific resistance, and the gauge factor when these heat treatments are performed in vacuum for 2 hours.
The temperature coefficient of resistance increased from negative to positive, and the resistivity decreased with increasing heating temperature, but the gauge factor showed a monotonic increasing trend. Very small TC of 0.03 × 10 ⁻⁴ / ° C. in the sample heat-treated at a temperature of 450 ° C.
Large gauge factors of R and 10.9 were obtained. The heat treatment of the present invention was found to be effective in producing a highly sensitive and highly stable strain gauge.

[0032]

[Table 2]

Example 3 Sample No. 53 (Composition: Cr _- 4
% N _- 1.2% Al _- 1.6% Si) Production and evaluation of alloy thin film Cr having a purity of 99.99% and A having a purity of 99.9%
l and 99.999% pure Si are converted to 97.0% C
r, a mixture of 1.3% Al and 1.7% Si is melted and alloyed in a high-frequency melting furnace, and about 1 g of the alloy is used as an evaporation source material. Using this raw material, a thin film having a thickness of 1.2 μm is produced by vacuum evaporation under the following conditions in a vacuum evaporation apparatus in a nitrogen stream. The substrate is covered with a metal mask before film formation so that a gauge pattern can be formed during film formation. Degree of vacuum 6 × 10 ⁻⁷ Torr Substrate Polyimide (thickness 0.1 mm) Substrate temperature 200 ° C. Nitrogen gas flow rate 10 SCCM Nitrogen gas pressure 10 mtorr Substrate-evaporation source distance 180 mm Deposition rate 130 ° / min. After taking out and replacing the mask covering the substrate, Cu for the electrode is again
Film is formed, as a result of the measurement of the temperature coefficient of resistance and gage factor in the four-terminal method by welding clothing wire diameter 0.2mm using solder, respectively _- 5.4 × 10 -4 ^/ ℃ and A value of 7.9 was obtained. Next, the obtained thin film is heated in various atmospheres at various temperatures of 200 ° C. to 1000 ° C. for an appropriate time, and then cooled in a furnace to room temperature (cooling rate: 500 ° C./hour).
did. Table 3 shows the heat treatment conditions and the measured gauge factor, specific resistance, and temperature coefficient of resistance (TCR). As in Example 1, the gauge factor was improved in any of the atmospheres, and showed a large value. Also, similarly, the temperature coefficient of resistance increases with an increase in the heat treatment temperature, and a very small TCR of 0.1 × 10 ⁻⁴ / ° C. and a large gauge factor of 8.1 in the sample heat-treated at 450 ° C. Indicated. That is, it became clear that a high-sensitivity and high-stability strain sensor can be provided by using the alloy of the present invention.

[0034]

[Table 3]

A large number of film formation experiments according to the present invention have been intensively performed, and Cr100 has been deposited on various substrates using various film formation methods.
The _-x-y N x _{M y} thin film was fabricated. In Tables 4 and 5,
Among the samples containing as much as 4% of nitrogen, the as-deposited samples or the samples subjected to the heat treatment under various conditions, the gauge factor (K) and the ratio of the representative thin film of the present invention. Resistance (ρ) and temperature coefficient of resistance (TCR)
Are shown together with the composition of the subcomponents and the heat treatment conditions.

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

The Cr _- N-based strain resistive film of the present invention has a low temperature coefficient of resistance over a wide temperature range, and has a significantly higher gauge factor than conventional materials. That, Cr of the present invention - _N Motoibitsu resistance film, a gauge index of at least 2, and temperature coefficient of resistance _- because (4-4) is within × 10 -4 ^/ ° C., the strain sensor using the same Has the effect of exhibiting high sensitivity and high stability. Therefore, the strain gauge made of the thin film of the present invention is suitable for a load cell, a strain sensor, a weigh scale, an accelerometer, various stress / strain gauges, various security devices, and the like.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing the temperature dependence of the electrical resistance of a Cr thin film manufactured using a normal vapor deposition apparatus or sputtering apparatus.

FIG. 2 is a characteristic diagram showing a relationship between a nitrogen concentration and a TCR in a Cr _100-x N _x strain resistance film.

FIG. 3 is a characteristic diagram showing a relationship between a heat treatment temperature and a TCR in a Cr ₉₆ N ₄ strain resistance film.

FIG. 4 shows an X-ray diffraction pattern of a Cr ₉₆ N ₄ strain resistance film at each heat treatment temperature.

FIG. 5 shows Cr _96-y N ₄ M n _y (y = 0,
1, 2, 3) Characteristic diagrams showing resistance temperature curves of strain resistance films.

FIG. 6 shows Be, Mg, and C added as subcomponents.
FIG. 4 is a characteristic diagram showing a temperature coefficient of resistance at 0 to 50 ° C. and a gauge factor at room temperature (20 ° C.) with respect to the amounts of a, Sr, and Ba.

FIG. 7 shows Fe, Co, and Mn added as subcomponents.
FIG. 3 is a characteristic diagram showing a temperature coefficient of resistance at 0 to 50 ° C. and a gauge factor at room temperature (20 ° C.) with respect to the amount of Al and Al.

FIG. 8 shows Ti, V, Zr,
FIG. 4 is a characteristic diagram showing a temperature coefficient of resistance at 0 to 50 ° C. and a gauge factor at room temperature (20 ° C.) with respect to the amounts of Nb, Hf, and Ta.

FIG. 9 shows Ti, V, Zr,
Nb, Hf, Ta, Ni, Ge, Si, C, N, P, S
FIG. 4 is a characteristic diagram showing a temperature coefficient of resistance at 0 to 50 ° C. and a gauge factor at room temperature (20 ° C.) with respect to the amounts of e and Te.

FIG. 10 shows Ru, Rh,
0-5 relative to the amount of Re, Os, Ir, Pt and Pd
FIG. 4 is a characteristic diagram showing a temperature coefficient of resistance at 0 ° C. and a gauge factor at room temperature (20 ° C.).

FIG. 11 shows that Ag, Au,
FIG. 4 is a characteristic diagram showing the temperature coefficient of resistance at 0 to 50 ° C. and the gauge factor at room temperature (20 ° C.) with respect to the amounts of Y, La and Ce.

FIG. 12 shows Pb, Sn, and Pb added as subcomponents.
0 to 50 relative to the amount of As, Sb, Bi, W and Mo
FIG. 3 is a characteristic diagram showing a temperature coefficient of resistance at ° C. and a gauge factor at room temperature (about 20 ° C.).

FIG. 13 shows B, Ga, and I added as subcomponents.
FIG. 4 is a characteristic diagram showing a temperature coefficient of resistance at 0 to 50 ° C. and a gauge factor at room temperature (about 20 ° C.) with respect to the amounts of n, Tl, Cu, and Zn.

FIG. 14: Sample No. 14 (composition: Cr _- 4% N _- 6%)
FIG. 4 is a characteristic diagram showing a relationship between a heat treatment temperature and a temperature coefficient of resistance, a specific resistance, and a gauge factor when a heat treatment is performed on the alloy thin film of V) in vacuum for 2 hours.

Claims (3)

[Claims] 1. A represented by the general formula _{Cr 100-x-y N x} M y, M is Ti, V, Nb, Ta, Ni, Zr, Hf, S
i, Ge, C, O, P, Se, Te, Zn, Cu, B
i, Fe, Mo, W, As, Sn, Sb, Pb, B, G
a, In, Tl, Ru, Rh, Re, Os, Ir, P
t, Pd, Ag, Au, Co, Be, Mg, Ca, S
r, Ba, Mn, Al and one or more elements selected from rare earth elements, and the composition ratios x and y are 0.0001 ≦ x ≦ 30, 0 ≦ y ≦ 30, 0. 00
It has 01 ≦ x + y ≦ 50 the relationship, the crystal structure is mainly bcc structure or predominantly mixed structure of bcc structure and the A15 type structure, a gauge index of at least 2, and the temperature coefficient of electrical resistance _{(- 4 ~} 4) Cr, characterized in that within _× 10 ^-4 / ℃ _- N Motoibitsu resistive film. 2. In a gas atmosphere containing nitrogen, a general formula cr _100-xy N is formed by a vapor deposition method or a sputtering method.
_x M _y , where M is Ti, V, Nb, Ta, Ni, Z
r, Hf, Si, Ge, C, O, P, Se, Te, Z
n, Cu, Bi, Fe, Mo, W, As, Sn, Sb,
Pb, B, Ga, In, Tl, Ru, Rh, Re, O
s, Ir, Pt, Pd, Ag, Au, Co, Be, M
g, Ca, Sr, Ba, Mn, Al and one or more elements selected from rare earth elements, and the composition ratio x, y is 0.0001 ≦ x ≦ 30, 0 ≦ y ≦ in atomic%. 3
0, 0.0001 ≦ x + y ≦ 50, and a Cr _— N-based strain resistive film having a crystal structure mainly composed of a bcc structure or a mixed structure mainly composed of a bcc structure and an A15 type structure is formed on an insulating substrate. Or a film is formed on an insulating film formed on a conductive substrate.
A method for producing a Cr _- N-based strain-resistant film, comprising heat-treating at a temperature of from 00C to 1000C. 3. A strain sensor using the Cr _— N-based strain resistance film according to claim 1.