JP6908554B2 - Strain resistance film and strain sensor, and their manufacturing method - Google Patents

Strain resistance film and strain sensor, and their manufacturing method Download PDF

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JP6908554B2
JP6908554B2 JP2018082592A JP2018082592A JP6908554B2 JP 6908554 B2 JP6908554 B2 JP 6908554B2 JP 2018082592 A JP2018082592 A JP 2018082592A JP 2018082592 A JP2018082592 A JP 2018082592A JP 6908554 B2 JP6908554 B2 JP 6908554B2
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英二 丹羽
英二 丹羽
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本発明は、高温で優れた特性を有する歪抵抗膜および歪センサ、ならびにそれらの製造方法に関する。 The present invention relates to strain resistance films and strain sensors having excellent properties at high temperatures, and methods for manufacturing them.

歪センサは、薄膜、細線または箔形状のセンサ材の電気抵抗が弾性歪によって変化する現象を利用するものであり、その抵抗変化を測定することにより、歪や応力の計測ならびに変換に用いられる。 The strain sensor utilizes a phenomenon in which the electrical resistance of a thin film, fine wire, or foil-shaped sensor material changes due to elastic strain, and is used for measuring and converting strain and stress by measuring the resistance change.

歪センサの感度は、ゲージ率Kによって決まり、Kの値は一般に以下の(1)式で与えられる。
K=(ΔR/R)/(Δl/l)=1+2σ+(Δρ/ρ)/(Δl/l) (1)
ここで、R、σおよびρは、それぞれセンサ材である薄膜、細線または箔の全抵抗、ポアソン比および比電気抵抗である。またlは被測定体の全長であり、よってΔl/lは被測定体に生じる歪を表す。一般に、金属・合金におけるσはほぼ0.3であるから、前記の式における右辺第1項と第2項の合計は約1.6でほぼ一定の値となる。したがってゲージ率を大きくするためには、前記の式における第3項が大きいことが必須条件である。すなわち、材料に引っ張り変形を与えたとき材料の長さ方向の電子構造が大幅に変化し、比電気抵抗の変化量Δρ/ρが増加することによる。
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 (1).
K = (ΔR / R) / (Δl / l) = 1 + 2σ + (Δρ / ρ) / (Δl / l) (1)
Here, R, σ, and ρ are the total resistance, Poisson's ratio, and specific electrical resistance of the thin film, thin wire, or foil that is the sensor material, respectively. Further, l is the total length of the object to be measured, and Δl / l represents the strain generated in the object to be measured. In general, since σ in metals and alloys is approximately 0.3, the sum of the first and second terms on the right side in the above equation is approximately 1.6, which is a substantially constant value. Therefore, in order to increase the gauge ratio, it is an essential condition that the third term in the above equation is large. That is, when the material is subjected to tensile deformation, the electronic structure in the length direction of the material changes significantly, and the amount of change in specific electrical resistance Δρ / ρ increases.

そこで近年になって注目されたのが、バルクのゲージ率として26〜28という非常に大きい値が報告されていたクロミウム(Cr)である。Crは加工が非常に困難であるが、加工を必要としない薄膜化によって歪センサに応用することができ、Crは薄膜化してもゲージ率が約15と依然として大きいため、Cr薄膜が歪センサとして注目されている(例えば特許文献1)。 Therefore, in recent years, attention has been paid to chromium (Cr), which has been reported to have a very large bulk gauge ratio of 26 to 28. Although Cr is very difficult to process, it can be applied to a strain sensor by thinning it without processing, and even if Cr is thinned, the gauge ratio is still large at about 15, so the Cr thin film can be used as a strain sensor. It is attracting attention (for example, Patent Document 1).

一方、歪センサは、高いゲージ率を有するとともに温度に対する安定性が高いことが要求されるが、Cr薄膜では、温度安定性の指標である抵抗温度係数(TCR)が正の大きな値を示し、安定性の点で問題がある。これに対して、ゲージ率が高く、TCRが小さい薄膜材料としてCr−N膜が提案されている(例えば特許文献2)。また、温度安定性の指標としてはゲージ率の温度係数(感度温度係数)(TCS)も重要であり、TCRおよびTCSが低いCr−N薄膜も提案されている(特許文献3)。 On the other hand, the strain sensor is required to have a high gauge ratio and high stability with respect to temperature, but in the Cr thin film, the temperature coefficient of resistance (TCR), which is an index of temperature stability, shows a large positive value. There is a problem in terms of stability. On the other hand, a Cr—N film has been proposed as a thin film material having a high gauge ratio and a small TCR (for example, Patent Document 2). Further, the temperature coefficient of gauge ratio (sensitivity temperature coefficient) (TCS) is also important as an index of temperature stability, and a Cr—N thin film having low TCR and TCS has also been proposed (Patent Document 3).

一方、近年、自動車および航空機等の内燃機関関連、射出成型、地熱発電、油田開発、火力発電のタービン関連など、200〜700℃の高温領域においてゲージ率が高く高感度な各種力学量のセンシングが強く要望されている。 On the other hand, in recent years, sensing of various dynamic quantities with high gauge ratio and high sensitivity in the high temperature range of 200 to 700 ° C, such as internal combustion engine related to automobiles and aircraft, injection molding, geothermal power generation, oil field development, turbine related to thermal power generation, etc. It is strongly requested.

特開昭61−256233号公報Japanese Unexamined Patent Publication No. 61-256233 特許第3642449号公報Japanese Patent No. 3642449 特開2015−031633号公報Japanese Unexamined Patent Publication No. 2015-031633

ところで、上記特許文献2、3に示されたCr−N薄膜を用いた歪センサは、高温領域での使用は考慮されていないため、高温領域でのゲージ率は測定しておらず不明である。 By the way, since the strain sensor using the Cr—N thin film shown in Patent Documents 2 and 3 is not considered for use in the high temperature region, the gauge ratio in the high temperature region is not measured and is unknown. ..

本発明は、このような事情に鑑みてなされたものであり、所定の高温領域において、高いゲージ率および温度安定性を示す歪抵抗膜および歪センサ、ならびにそれらの製造方法を提供することを課題とする。 The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a strain resistance film and a strain sensor exhibiting a high gauge ratio and temperature stability in a predetermined high temperature region, and a method for manufacturing the same. And.

本発明者は、先に、Cr薄膜を歪抵抗膜として用い、所定の高温での使用温度領域の上限よりも50℃以上高い温度で大気中において所定時間の熱処理を施すことにより、その高温での使用温度範囲において、実用的なゲージ率が得られることを見出し、特許出願した(特開2018−036143)。 The present inventor first uses a Cr thin film as a strain resistance film and heat-treats it in the air at a temperature 50 ° C. or higher higher than the upper limit of the operating temperature range at a predetermined high temperature for a predetermined time at that high temperature. We have found that a practical gauge ratio can be obtained in the operating temperature range of the above, and applied for a patent (Japanese Patent Laid-Open No. 2018-036143).

しかし、このようなCr薄膜は、100℃ではゲージ率の値が14程度であるが、100℃を超えるとゲージ率が低下して行き、250℃以上になると6程度、350℃以上になると4程度まで低下する。この値は、実用に供することができる値ではあるものの、常温から100℃におけるゲージ率よりもかなり小さい値である。また、温度安定性係数(感度温度係数)(TCS)が2000ppm/℃以下であり、さらなる温度安定性も望まれている。 However, such a Cr thin film has a gauge ratio value of about 14 at 100 ° C., but the gauge ratio decreases when it exceeds 100 ° C., about 6 when it reaches 250 ° C. or higher, and 4 when it reaches 350 ° C. or higher. It drops to a degree. Although this value can be put to practical use, it is considerably smaller than the gauge ratio at room temperature to 100 ° C. Further, the temperature stability coefficient (sensitivity temperature coefficient) (TCS) is 2000 ppm / ° C. or less, and further temperature stability is also desired.

そこで100℃以上の高温において大きなゲージ率および優れたTCS特性を示す材料について検討を行った結果、所定組成のCr−Al−N薄膜は、−50〜300℃でのゲージ率が高く、温度安定性も高いことを見出した。 Therefore, as a result of investigating a material showing a large gauge ratio and excellent TCS characteristics at a high temperature of 100 ° C. or higher, the Cr—Al—N thin film having a predetermined composition has a high gauge ratio at -50 to 300 ° C. and is temperature stable. I found that it was also highly sexual.

本発明は、このような知見に基づいてなされたものであり、以下の(1)〜(12)を提供する。 The present invention has been made based on such findings, and the following (1) to ( 12 ) are provided.

(1)一般式Cr100−x−yAl
(ただし、x、yは原子比率(at.%)であり、4≦x≦25、0.1≦y≦20である。)で表され、−50℃以上300℃以下の温度範囲において、ゲージ率が4以上であり、酸素を含む明確な幅を持つ粒界が存在しないことを特徴とする歪抵抗膜。
(1) General formula Cr 100-xy Al x N y
(However, x and y are atomic ratios (at.%) And are represented by 4 ≦ x ≦ 25 and 0.1 ≦ y ≦ 20), and in a temperature range of −50 ° C. or higher and 300 ° C. or lower. Ri der gauge factor of 4 or more, strain resistance film, wherein a grain boundary having a clear width including oxygen is not present.

(2)−50℃以上200℃以下の温度範囲において、感度温度係数(TCS)が、±1500ppm/℃以内であることを特徴とする(1)に記載の歪抵抗膜。 (2) The strain resistance film according to (1), wherein the sensitivity temperature coefficient (TCS) is within ± 1500 ppm / ° C. in a temperature range of −50 ° C. or higher and 200 ° C. or lower.

(3)−50℃以上500℃以下の温度範囲において、抵抗温度係数(TCR)が、±500ppm/℃以内であることを特徴とする(1)または(2)に記載の歪抵抗膜。 (3) The strain resistance film according to (1) or (2), wherein the temperature coefficient of resistance (TCR) is within ± 500 ppm / ° C. in a temperature range of −50 ° C. or higher and 500 ° C. or lower.

)上記(1)から()のいずれかの歪抵抗膜を起歪構造体上に形成してなることを特徴とする歪センサ。 ( 4 ) A strain sensor characterized in that the strain resistance film according to any one of (1) to ( 3) above is formed on a strain-causing structure.

(5) ガス圧が16mTorr以下で高周波スパッタリングすることにより、
一般式Cr100−x−yAl
(ただし、x、yは原子比率(at.%)であり、4≦x≦25、0.1≦y≦20である。)で表される薄膜に、300℃以上700℃以下の温度で熱処理を施し、−50℃以上300℃以下の温度範囲において、ゲージ率が4以上の歪抵抗膜とすることを特徴とする歪抵抗膜の製造方法。
(5) By high-frequency sputtering at a gas pressure of 16 mTorr or less,
General formula Cr 100-xy Al x N y
(However, x and y are atomic ratios (at.%), And 4 ≦ x ≦ 25 and 0.1 ≦ y ≦ 20) on the thin film at a temperature of 300 ° C. or higher and 700 ° C. or lower. A method for producing a strain resistance film, which comprises performing heat treatment to form a strain resistance film having a gauge ratio of 4 or more in a temperature range of −50 ° C. or higher and 300 ° C. or lower.

)前記熱処理によって膜表面に表面保護膜が形成されることを特徴とする(5)に記載の歪抵抗膜の製造方法。 ( 6 ) The method for producing a strain-resistant film according to (5) , wherein a surface protective film is formed on the film surface by the heat treatment.

)前記表面保護膜は、Crおよび不可避的不純物からなることを特徴とする()に記載の歪抵抗膜の製造方法。 ( 7 ) The method for producing a strain resistance film according to (6 ), wherein the surface protective film is composed of Cr 2 O 3 and unavoidable impurities.

)−50℃以上200℃以下の温度範囲において、感度温度係数(TCS)が、±1500ppm/℃以内であることを特徴とする(5)から()のいずれかに記載の歪抵抗膜の製造方法。 ( 8 ) The strain resistance according to any one of (5) to (7 ), wherein the sensitivity temperature coefficient (TCS) is within ± 1500 ppm / ° C. in the temperature range of −50 ° C. or higher and 200 ° C. or lower. Membrane manufacturing method.

)−50℃以上500℃以下の温度範囲において、抵抗温度係数(TCR)が、±500ppm/℃以内であることを特徴とする(5)から()のいずれかに記載の歪抵抗膜の製造方法。 ( 9 ) The strain resistance according to any one of (5) to (8 ), wherein the temperature coefficient of resistance (TCR) is within ± 500 ppm / ° C. in the temperature range of −50 ° C. or higher and 500 ° C. or lower. Method of manufacturing a membrane.

10ガス圧が16mTorr以下で高周波スパッタリングすることにより、
一般式Cr100−x−yAl
(ただし、x、yは原子比率(at.%)であり、4≦x≦25、0.1≦y≦20である。)で表される薄膜を起歪構造体上に形成し、300℃以上700℃以下の温度で熱処理を施し、上記(1)から(3)のいずれかの歪抵抗膜とすることにより歪センサを得ることを特徴とする歪センサの製造方法。
( 10 ) By high-frequency sputtering at a gas pressure of 16 mTorr or less,
General formula Cr 100-xy Al x N y
(However, x and y are atomic ratios (at.%), And 4 ≦ x ≦ 25 and 0.1 ≦ y ≦ 20). A method for manufacturing a strain sensor, which comprises subjecting a strain sensor to a strain resistance film according to any one of (1) to (3) above by performing heat treatment at a temperature of ° C. or higher and 700 ° C. or lower to obtain a strain sensor.

11)前記熱処理によって膜表面に表面保護膜が形成されることを特徴とする(10)に記載の歪センサの製造方法。 ( 11 ) The method for manufacturing a strain sensor according to (10) , wherein a surface protective film is formed on the film surface by the heat treatment.

12)前記表面保護膜は、Crおよび不可避的不純物からなることを特徴とする(11)に記載の歪センサの製造方法。 ( 12 ) The method for manufacturing a strain sensor according to (11 ), wherein the surface protective film is composed of Cr 2 O 3 and unavoidable impurities.

本発明によれば、所定の高温領域において、高いゲージ率および温度安定性を示す歪抵抗膜および歪センサ、ならびにそれらの製造方法が提供される。 INDUSTRIAL APPLICABILITY According to the present invention, a strain resistance film and a strain sensor exhibiting a high gauge ratio and temperature stability in a predetermined high temperature region, and a method for manufacturing the same are provided.

Cr−Al合金のAlの添加量とネール温度の関係を示す図である。It is a figure which shows the relationship between the addition amount of Al of Cr—Al alloy and the Néel temperature. Cr−Mn合金のMnの添加量とネール温度の関係を示す図である。It is a figure which shows the relationship between the addition amount of Mn of a Cr-Mn alloy, and the Néel temperature. 高温歪印加電気抵抗測定装置を示す概略構成図である。It is a schematic block diagram which shows the electric resistance measuring apparatus which applied high temperature strain. 曲げ試験シーケンスを示す図である。It is a figure which shows the bending test sequence. Cr薄膜およびCr−N薄膜の、測定温度とゲージ率および抵抗値との関係を示す図である。It is a figure which shows the relationship between the measurement temperature, the gauge ratio and the resistance value of a Cr thin film and a Cr—N thin film. Alチップ数nを0〜16にして製造した薄膜の測定温度とゲージ率との関係を示す図である。It is a figure which shows the relationship between the measurement temperature and the gauge ratio of the thin film manufactured by setting the number n of Al chips from 0 to 16. Alチップ数n=8にして製造した薄膜について、大気中500℃で熱処理後、抵抗値の温度に対する変化を把握した結果を示す図である。It is a figure which shows the result of grasping the change with respect to the temperature of a thin film produced by setting the number of Al chips n = 8 after heat treatment at 500 degreeC in the atmosphere. Alチップ数が8の場合について、大気中500℃で熱処理を施した試料と、大気中700℃で熱処理を施した試料についてゲージ率を比較して示す図である。In the case where the number of Al chips is 8, the gauge ratios of the sample heat-treated at 500 ° C. in the air and the sample heat-treated at 700 ° C. in the air are compared and shown. Alチップ数nを0〜16として成膜した後、大気中500℃で熱処理を施した試料における、測定温度とTCSとの関係を示す図である。It is a figure which shows the relationship between the measurement temperature and TCS in the sample which was heat-treated at 500 degreeC in the atmosphere after forming a film with the number n of Al chips set to 0 to 16. Alチップ数が8の場合について、大気中500℃で熱処理を施した試料と、大気中700℃で熱処理を施した試料の、測定温度とTCSとの関係を示す図である。It is a figure which shows the relationship between the measurement temperature and TCS of the sample which was heat-treated at 500 degreeC in the atmosphere, and the sample which was heat-treated at 700 degreeC in the air in the case of 8 Al chips. Alチップ数nを0〜16にして成膜した後、種々の条件で熱処理した試料の、チップ数と室温近傍におけるTCRを示す図である。It is a figure which shows the number of chips and TCR in the vicinity of room temperature of the sample which was heat-treated under various conditions after forming a film with the number of Al chips n set to 0 to 16. Alチップ数nを0〜16にして成膜した後、大気中500℃で熱処理した試料の、測定温度と抵抗値との関係を示す図である。It is a figure which shows the relationship between the measurement temperature and the resistance value of the sample which was heat-treated at 500 degreeC in the atmosphere after forming a film with the number n of Al chips set to 0 to 16. Alチップ数nを8にして成膜した後、大気中500℃で熱処理を施した試料と、大気中700℃で熱処理を施した試料の、測定温度と抵抗値の関係を示す図である。It is a figure which shows the relationship between the measurement temperature and the resistance value of the sample which was heat-treated at 500 degreeC in the air after forming a film with the number of Al chips n being eight, and the sample which was heat-treated at 700 degreeC in the air. Alチップ数nを0〜16にして成膜した後、大気中500℃で熱処理した試料の、測定温度とTCRとの関係を示す図である。It is a figure which shows the relationship between the measurement temperature and TCR of the sample which was heat-treated at 500 degreeC in the atmosphere after forming a film with the number n of Al chips set to 0 to 16. Alチップ数が8の場合について、大気中500℃で熱処理を施した試料と、大気中700℃で熱処理を施した試料の、測定温度とTCRとの関係を示す図である。It is a figure which shows the relationship between the measurement temperature and TCR of the sample which was heat-treated at 500 degreeC in the atmosphere, and the sample which was heat-treated at 700 degreeC in the atmosphere in the case of the case where the number of Al chips is eight. Alチップ数nを0〜16にして成膜した後、種々の条件で熱処理した試料の、チップ数と室温近傍のTCSとの関係を示す図である。It is a figure which shows the relationship between the number of chips and TCS in the vicinity of room temperature of a sample which was heat-treated under various conditions after forming a film with the number of Al chips n set to 0 to 16. Alチップ数nを0〜16にして成膜した後、種々の条件で熱処理した試料の、チップ数と室温近傍のゲージ率との関係を示す図である。It is a figure which shows the relationship between the number of chips and the gauge ratio near room temperature of the sample which was heat-treated under various conditions after forming a film with the number of Al chips n set to 0 to 16. Alチップ数n=0にして製造したCr−N:Al(0)薄膜について、大気中500℃で熱処理後、抵抗値の温度に対する変化を把握した結果を示す図である。It is a figure which shows the result of grasping the change with respect to the temperature of the Cr—N: Al (0) thin film produced with the number of Al chips n = 0 after heat treatment at 500 degreeC in the atmosphere. Alチップ数n=4にして製造したCr−N:Al(4)薄膜について、大気中500℃で熱処理後、抵抗値の温度に対する変化を把握した結果を示す図である。It is a figure which shows the result of grasping the change with respect to the temperature of the Cr—N: Al (4) thin film produced with the number of Al chips n = 4 after heat treatment at 500 degreeC in the atmosphere. Alチップ数n=8にして製造したCr−N:Al(8)薄膜について、大気中500℃で熱処理後、抵抗値の温度に対する変化を把握した結果を示す図である。It is a figure which shows the result of grasping the change with respect to the temperature of the Cr—N: Al (8) thin film produced with the number of Al chips n = 8 after heat treatment at 500 degreeC in the atmosphere. Alチップ数n=12にして製造したCr−N:Al(12)薄膜について、大気中500℃で熱処理後、抵抗値の温度に対する変化を把握した結果を示す図である。It is a figure which shows the result of grasping the change with respect to the temperature of the Cr—N: Al (12) thin film produced with the number of Al chips n = 12 after heat treatment at 500 degreeC in the atmosphere. Alチップ数n=16にして製造したCr−N:Al(16)薄膜について、大気中500℃で熱処理後、抵抗値の温度に対する変化を把握した結果を示す図である。It is a figure which shows the result of grasping the change with respect to the temperature of the Cr—N: Al (16) thin film produced with the number of Al chips n = 16 after heat treatment at 500 degreeC in the atmosphere. Alチップ数n=8にして製造したCr−N:Al(8)薄膜について、大気中700℃で熱処理後、抵抗値の温度に対する変化を把握した結果を示す図である。It is a figure which shows the result of grasping the change with respect to the temperature of the Cr—N: Al (8) thin film produced with the number of Al chips n = 8 after heat treatment at 700 degreeC in the atmosphere. Alチップ数nと、Al量(at.%)との関係を示す図である。It is a figure which shows the relationship between the number of Al chips n, and the amount of Al (at.%). Alチップ数n=4で成膜した後、大気中500℃で0.5時間の熱処理を施した試料を示すSEM写真であり、スパッタガス圧が20mTorrと5mTorr場合を比較して示すものである。It is an SEM photograph showing a sample which was heat-treated at 500 ° C. for 0.5 hour in the air after forming a film with the number of Al chips n = 4, and shows a comparison between the cases where the sputtering gas pressure is 20 mTorr and 5 mTorr. .. Alチップ数n=8で成膜した後、大気中500℃で0.5時間の熱処理を施した試料を示すTEM写真であり、スパッタガス圧が20mTorrと5mTorr場合を比較して示すものである。It is a TEM photograph showing a sample which has been heat-treated at 500 ° C. for 0.5 hour in the air after forming a film with the number of Al chips n = 8, and shows a comparison between the cases where the sputtering gas pressure is 20 mTorr and 5 mTorr. .. Alチップ数n=16で成膜した後、大気中500℃で0.5時間の熱処理を施した試料を示すTEM写真であり、スパッタガス圧が20mTorrと5mTorr場合を比較して示すものである。It is a TEM photograph showing a sample which has been heat-treated at 500 ° C. for 0.5 hour in the air after forming a film with the number of Al chips n = 16, and shows a comparison between the cases where the sputtering gas pressure is 20 mTorr and 5 mTorr. .. Alチップ数n=8で成膜した後、大気中700℃で0.5時間の熱処理を施した試料を示すTEM写真であり、スパッタガス圧が20mTorrと5mTorr場合を比較して示すものである。It is a TEM photograph showing a sample which has been heat-treated at 700 ° C. for 0.5 hour in the air after forming a film with the number of Al chips n = 8, and shows a comparison between the cases where the sputtering gas pressure is 20 mTorr and 5 mTorr. .. Alチップ数n=8、Alチップ数n=16でスパッタガス圧5mTorrで成膜した場合の、as−depositedの試料を示すTEM写真である。6 is a TEM photograph showing an as-deposited sample when a film is formed with a sputter gas pressure of 5 mTorr with an Al chip number n = 8 and an Al chip number n = 16. Alチップ数n=8で成膜した場合の、as−depositedの試料、大気中500℃で0.5時間の熱処理を施した試料、および大気中700℃で0.5時間の熱処理を施した試料を示すTEM写真である。An as-deposited sample, a sample that had been heat-treated at 500 ° C. for 0.5 hours in the air, and a sample that had been heat-treated at 700 ° C. for 0.5 hours in the air when the film was formed with the number of Al chips n = 8. It is a TEM photograph which shows a sample. Alチップ数n=8でスパッタガス圧20mTorrの条件で成膜した後、大気中500℃で熱処理を施した試料のEDX面分析結果を示す図である。It is a figure which shows the EDX plane analysis result of the sample which was subjected to the heat treatment at 500 degreeC in the atmosphere after the film formation under the condition of the sputter gas pressure of 20 mTorr with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧5mTorrの条件で成膜した後、大気中500℃で熱処理を施した試料のEDX面分析結果を示す図である。It is a figure which shows the EDX plane analysis result of the sample which was subjected to the heat treatment at 500 degreeC in the atmosphere after the film formation under the condition of the sputter gas pressure of 5 mTorr with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧20mTorrの条件で成膜した後、大気中700℃で熱処理を施した試料のEDX面分析結果を示す図である。It is a figure which shows the EDX plane analysis result of the sample which was subjected to the heat treatment at 700 ° C. in the atmosphere after forming a film under the condition of sputter gas pressure of 20 mTorr with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧5mTorrの条件で成膜した後、大気中570℃で熱処理を施した試料のEDX面分析結果を示す図である。It is a figure which shows the EDX plane analysis result of the sample which was subjected to the heat treatment at 570 ° C. in the atmosphere after forming a film under the condition of sputter gas pressure of 5 mTorr with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧20mTorrの条件で成膜した後、大気中500℃で熱処理を施した試料のXPSによる深さ方向の組成プロファイルを示す図である。It is a figure which shows the composition profile in the depth direction by XPS of the sample which was heat-treated at 500 degreeC in the atmosphere after forming a film under the condition of sputter gas pressure of 20 mTorr with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧5mTorrの条件で成膜した後、大気中500℃で熱処理を施した試料のXPSによる深さ方向の組成プロファイルを示す図である。It is a figure which shows the composition profile in the depth direction by XPS of the sample which was heat-treated at 500 degreeC in the atmosphere after forming a film under the condition of sputter gas pressure of 5 mTorr with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧20mTorrの条件で成膜した後、大気中700℃で熱処理を施した試料のXPSによる深さ方向の組成プロファイルを示す図である。It is a figure which shows the composition profile in the depth direction by XPS of the sample which was heat-treated at 700 degreeC in the atmosphere after forming a film under the condition of sputter gas pressure of 20 mTorr with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧5mTorrの条件で成膜した後、大気中570℃で熱処理を施した試料のXPSによる深さ方向の組成プロファイルを示す図である。It is a figure which shows the composition profile in the depth direction by XPS of the sample which was heat-treated at 570 ° C. in the atmosphere after forming a film under the condition of sputter gas pressure of 5 mTorr with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧5mTorrで成膜時間を約5倍にして厚く成膜した後、大気中500℃で熱処理を施した試料の断面TEM写真である。It is a cross-sectional TEM photograph of a sample which was subjected to heat treatment at 500 ° C. in the air after forming a thick film by increasing the film forming time by about 5 times with a sputtering gas pressure of 5 mTor with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧5mTorrで成膜時間を約5倍にして厚く成膜した後、大気中500℃で熱処理を施した試料のEDX面分析結果を示す図である。It is a figure which shows the EDX plane analysis result of the sample which performed the heat treatment at 500 degreeC in the atmosphere after making the film formation time about 5 times by the sputter gas pressure of 5 mTor with the number of Al chips n = 8. Alチップ数n=8でスパッタガス圧5mTorrで成膜時間を約5倍にして厚く成膜した後、大気中500℃で熱処理を施した試料のXPSによる深さ方向の組成プロファイルを示す図である。It is a figure which shows the composition profile in the depth direction by XPS of a sample which was heat-treated at 500 degreeC in the atmosphere after forming a thick film by increasing the film formation time by about 5 times with a sputter gas pressure of 5 mTor with the number of Al chips n = 8. be.

以下、本発明の実施の形態について詳細に説明する。
常温ではゲージ率が大きいことが知られているCr薄膜、ならびにゲージ率が大きくTCRおよびTCSのゼロ近傍への調整を可能とするCr−N薄膜について高温でのゲージ率を調べた。その結果、100℃以上でゲージ率が急激に低下した。また、そのゲージ率の温度に対する変化率、すなわちTCSの絶対値が大きい傾向があり温度安定性が不十分になることがあった。
Hereinafter, embodiments of the present invention will be described in detail.
The gauge ratio at high temperature was investigated for the Cr thin film, which is known to have a large gauge ratio at room temperature, and the Cr—N thin film, which has a large gauge ratio and enables adjustment of TCR and TCS to near zero. As a result, the gauge rate dropped sharply at 100 ° C. or higher. In addition, the rate of change of the gauge rate with respect to temperature, that is, the absolute value of TCS tends to be large, and the temperature stability may be insufficient.

そこで、100℃以上の高温において大きなゲージ率および優れた温度安定性を示す材料について検討した。様々な検討を行って800℃までのゲージ率測定を可能にした装置と方法を用い、Cr−Nに様々な第3元素を添加したCr−N−X薄膜について、その添加量を変えて高温におけるゲージ率およびその挙動等の調査を行った。 Therefore, a material exhibiting a large gauge ratio and excellent temperature stability at a high temperature of 100 ° C. or higher was investigated. Using a device and method that made it possible to measure the gauge rate up to 800 ° C by conducting various studies, the Cr-NX thin film in which various third elements were added to Cr-N was subjected to high temperature by changing the addition amount. The gauge rate and its behavior were investigated.

XとしてAlを用い、300℃〜700℃で熱処理した試料、特に500℃以上で熱処理した試料では、Al量の増加にともなって、室温のゲージ率が100℃を超えても低減することなく、約300℃まで高温側に拡大する挙動が見出された。すなわち、室温のゲージ率が300℃まで変わらず4以上の値が得られた。また、200℃までゲージ率の値の変化が小さいことを初めて見出した。その結果、−50℃から200℃までのTCSが0±1500ppm/℃以内という良好な値を示す。 In the sample heat-treated at 300 ° C. to 700 ° C. using Al as X, especially the sample heat-treated at 500 ° C. or higher, the gauge ratio at room temperature does not decrease even if it exceeds 100 ° C. as the amount of Al increases. The behavior of expanding to the high temperature side up to about 300 ° C. was found. That is, the gauge ratio at room temperature did not change up to 300 ° C., and a value of 4 or more was obtained. It was also found for the first time that the change in the gauge ratio value was small up to 200 ° C. As a result, the TCS from −50 ° C. to 200 ° C. shows a good value within 0 ± 1500 ppm / ° C.

一方、300℃〜700℃で熱処理を施した試料では、Al量の増加にともなって、室温近傍のTCRは減少し負に大きな値を示した。それらの値は熱処理温度が高いほど(正の方向に)大きな値を示した。このことから、熱処理温度の上昇にともなってTCRは正方向に増加することが確認された。 On the other hand, in the sample subjected to the heat treatment at 300 ° C. to 700 ° C., the TCR near room temperature decreased and showed a negatively large value as the amount of Al increased. The higher the heat treatment temperature, the larger the values (in the positive direction). From this, it was confirmed that the TCR increases in the positive direction as the heat treatment temperature rises.

すなわち、Cr−N−Al薄膜において、窒素量とAl量と熱処理温度でTCRを制御可能であることが初めて明らかとなり、Cr−N−Al膜が500℃までの高温域においても±500ppm/℃以内の低TCRとなるものがあることが明らかとなった。また、このことから、高温用途に必要な、より高温で熱処理を施す場合においてもTCRを低減(=0)可能であることが明らかとなった。 That is, it became clear for the first time that the TCR can be controlled by the amount of nitrogen, the amount of Al, and the heat treatment temperature in the Cr—N—Al thin film, and ± 500 ppm / ° C. even in the high temperature range of the Cr—N—Al film up to 500 ° C. It became clear that some of them had a low TCR within. Further, from this, it was clarified that the TCR can be reduced (= 0) even when the heat treatment is performed at a higher temperature, which is necessary for high temperature applications.

また、Cr−N−Al薄膜において、TCRをほぼ0に調整可能な、500℃付近以上の高い温度で大気中において30分以上4時間以下の熱処理を施すことによって、400℃以下の温度範囲においては上記特性に加えて、抵抗値の安定性が100時間で±0.02%以内、すなわち±2ppm/h以内の良好な特性を示すことを見出した。これは、大気中熱処理の効果と考えられる。 Further, in the Cr—N—Al thin film, the TCR can be adjusted to almost 0, and the heat treatment is performed in the air at a high temperature of about 500 ° C. or higher for 30 minutes or more and 4 hours or less in a temperature range of 400 ° C. or lower. In addition to the above characteristics, it was found that the stability of the resistance value shows good characteristics within ± 0.02%, that is, within ± 2 ppm / h in 100 hours. This is considered to be the effect of heat treatment in the atmosphere.

一方、Cr系薄膜においては、一般に、その電気抵抗は、広い温度領域全般にわたっては通常の金属と同様に温度変化に対し正の傾きで変化するが、Crの反強磁性に関連するネール温度において極小値をとること、または傾きが変化することが知られている。すなわち、ネール温度近傍のそれ以下の温度領域では負の値または増加量の減少が生じて極小点または傾きが変化する点にてネール温度に至り、ネール温度からそれ以上の温度領域では再び正の傾きで抵抗値が増加していく挙動を示す。そこで、Cr−N−Al薄膜において抵抗値の温度依存性を調査した結果、ネール温度と考えられる極小値または傾きが変化する抵抗値が見出された。 On the other hand, in a Cr-based thin film, in general, its electric resistance changes with a positive slope with respect to a temperature change like a normal metal over a wide temperature range, but at the Néel temperature related to the antiferromagnetism of Cr. It is known to take a minimum value or change the slope. That is, in the temperature range below the Néel temperature, a negative value or a decrease in the amount of increase occurs and the Néel temperature is reached at the point where the minimum point or the slope changes, and in the temperature range above the Néel temperature, it is positive again. It shows the behavior that the resistance value increases with the inclination. Therefore, as a result of investigating the temperature dependence of the resistance value in the Cr—N—Al thin film, a minimum value considered to be the Néel temperature or a resistance value in which the slope changes was found.

Cr−N−Al薄膜においては、ゲージ率が、室温からネール温度直下近傍の温度まで一定の値を示し、ネール温度近傍で低減することが確認され、Al成分量の増加にともなって、ネール温度とともに、ゲージ率一定領域の高温側のゲージ率低減の傾斜部分が高温側へシフトしていく挙動が観察された。このことから、Cr−N−Al薄膜が上記のように高温領域まで大きなゲージ率を示す要因は、Al量の増加に追従するネール温度の高温化に関連があると考えられる。 In the Cr-N-Al thin film, the gauge ratio showed a constant value from room temperature to the temperature near the Néel temperature, and it was confirmed that the gauge ratio decreased in the vicinity of the Néel temperature. At the same time, it was observed that the inclined portion of the gauge ratio reduction on the high temperature side in the constant gauge ratio region shifted to the high temperature side. From this, it is considered that the factor that the Cr—N—Al thin film exhibits a large gauge ratio up to the high temperature region as described above is related to the increase in the Néel temperature that follows the increase in the amount of Al.

一方、過去の文献(E.Fawcett et al.:"Spin-density-wave antiferromagnetism in chromium alloys",Rev.Mod.Phys.,66(1),(1994).)には、AlとMnは、Crに加える量に応じて、ネール温度を500℃を超える温度まで上昇させ得ることが報告されている。 On the other hand, in the past literature (E. Fawcett et al .: "Spin-density-wave antiferromagnetism in chromium alloys", Rev.Mod.Phys., 66 (1), (1994).), Al and Mn are described as It has been reported that the Néel temperature can be raised to temperatures above 500 ° C. depending on the amount added to Cr.

具体的には、同文献の48ページには、Cr−Al合金の磁気状態図、つまりAlの添加量とネール温度の関係が示されている。その図を図1に示すが、図1からCrへのAlの添加量が約25at%までネール温度が上昇し、その最高温度は約800K、すなわち約530℃であることがわかる。 Specifically, page 48 of the same document shows a magnetic phase diagram of a Cr—Al alloy, that is, a relationship between the amount of Al added and the Néel temperature. The figure is shown in FIG. 1, and it can be seen from FIG. 1 that the amount of Al added to Cr increases the Néel temperature to about 25 at%, and the maximum temperature is about 800 K, that is, about 530 ° C.

また、Mnの添加量とネール温度の関係については、上記文献の85ページに示されている。その図を図2に示すが、この図の中で1〜20は、Mn添加量が異なっており、1がMn:0at.%、2がMn:0.1at.%、3がMn:0.2at.%、・・・・8がMn:0.7at.%、9が1.0at.%、・・・・16がMn:6.0at.%、・・・・19がMn:30at.%、20がMn:34at.%である。この図に示すように、Mn添加量が34at.%まで、ネール温度が一様に上昇し、その最高温度は約780K、すなわち約510℃であることがわかる。 The relationship between the amount of Mn added and the Néel temperature is shown on page 85 of the above document. The figure is shown in FIG. 2. In this figure, the amount of Mn added is different between 1 and 20, and 1 is Mn: 0 at. % 2 is Mn: 0.1 at. % 3 is Mn: 0.2 at. %, ... 8 is Mn: 0.7 at. %, 9 is 1.0 at. %, ... 16 is Mn: 6.0 at. %, ... 19 is Mn: 30 at. %, 20 is Mn: 34 at. %. As shown in this figure, the amount of Mn added is 34 at. It can be seen that the Néel temperature rises uniformly up to%, and its maximum temperature is about 780 K, or about 510 ° C.

以上は、Cr薄膜をベースにした結果であるが、上述したように、Cr−N薄膜をベースにしたCr−N−Al薄膜の場合においてもほぼ同様の挙動が得られたことから、Crの場合と同じメカニズムが作用したと考えられ、室温近傍の比較的大きなゲージ率が300℃まで保たれたと考えられる。 The above is the result based on the Cr thin film, but as described above, almost the same behavior was obtained in the case of the Cr—N—Al thin film based on the Cr—N thin film. It is considered that the same mechanism as in the case worked, and it is considered that the relatively large gauge ratio near room temperature was maintained up to 300 ° C.

しかしCr−N−Mn薄膜の場合、Cr−N−Al薄膜の場合とは異なり、Mn量の増加にともなってTCR値が変化することはなく、300℃を超える温度での熱処理によってTCR=0への調整は不可能であることがわかった。また、Cr−N−Mn薄膜を用いた歪センサのゲージ率は、従来のCr−N薄膜を用いた場合よりは大きいものの、Mn添加によって比較的大きく低減し、300℃以上の熱処理で室温付近のゲージ率が3程度と小さく、300℃までは温度の上昇にともなってゲージ率が上昇し、TCSが大きいことが確認された。また、TCSは、Mn添加量および熱処理温度の上昇にともなって、その値が正に増加し、低減は難しいと考えられる。したがって、Cr−N−Mn薄膜では、室温近傍〜200℃においてTCSが大きく、かつTCR調整ができず、ゲージ率が小さいことから、高温域での歪センサとして利用するには問題が多いことが判明した。 However, in the case of the Cr—N—Mn thin film, unlike the case of the Cr—N—Al thin film, the TCR value does not change as the amount of Mn increases, and TCR = 0 by heat treatment at a temperature exceeding 300 ° C. It turned out that adjustment to was impossible. Further, although the gauge ratio of the strain sensor using the Cr—N—Mn thin film is larger than that when the conventional Cr—N thin film is used, it is relatively greatly reduced by adding Mn, and is near room temperature by heat treatment at 300 ° C. or higher. It was confirmed that the gauge ratio of was as small as about 3, and the gauge ratio increased as the temperature increased up to 300 ° C., and the TCS was large. Further, it is considered that the value of TCS increases positively with the increase in the amount of Mn added and the heat treatment temperature, and it is difficult to reduce it. Therefore, since the Cr-N-Mn thin film has a large TCS at about room temperature to 200 ° C., TCR cannot be adjusted, and the gauge ratio is small, there are many problems in using it as a strain sensor in a high temperature range. found.

以上の結果から、本発明では、高感度でかつ高安定性な歪センサとしてCr−N−Al薄膜を用いる。すなわち、所定の組成を有するCr−N−Al薄膜を用いることによって、初めて−50℃から300℃の温度領域に亘ってゲージ率が4以上であり、かつ温度安定性が高いことを見出し本発明を完成するに至ったのである。また、−50℃から200℃の温度領域においてTCSが0±1500ppm/℃とゲージ率変化が小さく、さらに、−50から500℃の温度領域において、TCRが±500ppm以内に低減調整が可能であり、さらに、400℃以下の温度領域においては100時間にわたる高温保持を行っても抵抗値がほとんど変化しないことを確認しており、良好な抵抗の安定性も得ることができる。 From the above results, in the present invention, a Cr—N—Al thin film is used as a highly sensitive and highly stable strain sensor. That is, the present invention has found that by using a Cr—N—Al thin film having a predetermined composition, the gauge ratio is 4 or more and the temperature stability is high over the temperature range of −50 ° C. to 300 ° C. for the first time. Was completed. Further, the gauge ratio change is small as TCS is 0 ± 1500 ppm / ° C. in the temperature range of -50 ° C to 200 ° C, and the TCR can be reduced and adjusted within ± 500 ppm in the temperature range of -50 to 500 ° C. Furthermore, it has been confirmed that the resistance value hardly changes even if the high temperature is maintained for 100 hours in the temperature range of 400 ° C. or lower, and good resistance stability can be obtained.

このような優れた特性により、本発明の歪センサは、各種力学量センサへの応用も可能となる。 Due to such excellent characteristics, the strain sensor of the present invention can be applied to various dynamic quantity sensors.

本発明の歪センサにおいて、歪抵抗膜は、一般式Cr100−x−yAlで表され、x、yは原子比率(at.%)であり、4≦x≦25、0.1≦y≦20である。4≦x≦25としたのは、CrにAlを添加した場合と同様、CrまたはCr−NにAlを添加した場合に、4≦x≦25の範囲で、ネール温度の上昇が見られるからである。また、0.1≦y≦20としたのは、この範囲を外れると、TCRが±500ppm/℃よりも大きくなり、かつ、yが20を超えるとゲージ率が5よりも小さくなるからである。xのより好ましい範囲は10≦x≦25である。xがこの範囲で、−50℃以上300℃以下の温度範囲におけるゲージ率を6以上とすることができる。 In the strain sensor of the present invention, the strain resistance film is represented by the general formula Cr 100-x-y Al x N y, x, y is the atomic ratio (at.%), 4 ≦ x ≦ 25,0. 1 ≦ y ≦ 20. The reason why 4 ≦ x ≦ 25 is set is that when Al is added to Cr or Cr−N, the nail temperature rises in the range of 4 ≦ x ≦ 25, as in the case where Al is added to Cr. Is. Further, the reason why 0.1 ≦ y ≦ 20 is set is that when the range is out of this range, the TCR becomes larger than ± 500 ppm / ° C., and when y exceeds 20, the gauge ratio becomes smaller than 5. .. A more preferred range of x is 10 ≦ x ≦ 25. In this range of x, the gauge ratio in the temperature range of −50 ° C. or higher and 300 ° C. or lower can be set to 6 or higher.

次に、高温におけるゲージ率の測定装置および方法について説明する。
上述したように、本発明は高温領域でのゲージ率が高い抵抗薄膜および歪センサを提供するものであり、高温でのゲージ率を把握することが必要であるが、従来、高温におけるゲージ率の測定方法が確立されていなかった。
Next, a device and a method for measuring the gauge ratio at high temperature will be described.
As described above, the present invention provides a resistance thin film and a strain sensor having a high gauge ratio in a high temperature region, and it is necessary to grasp the gauge ratio at a high temperature. The measurement method has not been established.

このため、高温におけるゲージ率を測定することができる装置と方法について様々な検討を行った結果、図3に示す高温歪印加電気抵抗測定装置に想到した。 Therefore, as a result of various studies on a device and a method capable of measuring the gauge ratio at a high temperature, the high temperature strain applied electric resistance measuring device shown in FIG. 3 was conceived.

図3の装置は、大気中で1000℃付近まで加熱することができる温度制御機能付きの電気オーブン1を有し、電気オーブン1の上部には窓2が形成されている。窓2は蓋部材3により塞がれており、蓋部材3には、電気オーブン1内に向けて下方に延びる支持棒4が固定されている。支持棒4は、電気オーブン1内の測定台5を支持している。 The device of FIG. 3 has an electric oven 1 having a temperature control function capable of heating to around 1000 ° C. in the atmosphere, and a window 2 is formed above the electric oven 1. The window 2 is closed by a lid member 3, and a support rod 4 extending downward toward the inside of the electric oven 1 is fixed to the lid member 3. The support rod 4 supports the measuring table 5 in the electric oven 1.

測定台5の上には固定部材6が設けられており、固定部材6には、基板7上に高周波スパッタリング等により所定パターンの薄膜8が形成された試料20が片持ち梁固定されている。測定台5は箱状をなしており、内部に端子11を有する端子台10が設けられている。薄膜8と端子11はボンディングワイヤー9で接続されている。 A fixing member 6 is provided on the measuring table 5, and a sample 20 in which a thin film 8 having a predetermined pattern is formed on the substrate 7 by high-frequency sputtering or the like is fixed to the fixing member 6 by a cantilever beam. The measuring table 5 has a box shape, and a terminal block 10 having a terminal 11 inside is provided. The thin film 8 and the terminal 11 are connected by a bonding wire 9.

端子11には耐熱配線ケーブル(図示せず)が接続されている。耐熱配線ケーブルは窓2を介して引き出され、測定系(DMM)14に接続されている。また、電源15も耐熱配線ケーブルにより接続されている。 A heat-resistant wiring cable (not shown) is connected to the terminal 11. The heat-resistant wiring cable is pulled out through the window 2 and connected to the measurement system (DMM) 14. The power supply 15 is also connected by a heat-resistant wiring cable.

蓋部材3にはマイクロメータ12が固定されており、マイクロメータ12からは歪印加用押し込み棒13が下方に延び、試料20の自由端近傍に接触するようになっている。これにより、マイクロメータ12により歪印加用押し込み棒13を所定長さ降下させて、試料20に所定の歪を印加することができるようになっている。 A micrometer 12 is fixed to the lid member 3, and a strain applying push rod 13 extends downward from the micrometer 12 so as to come into contact with the vicinity of the free end of the sample 20. As a result, the strain applying push rod 13 can be lowered by a predetermined length by the micrometer 12 to apply a predetermined strain to the sample 20.

このような高温歪印加電気抵抗測定装置により高温でのゲージ率を測定するに際しては、電気オーブン1内の温度を約800℃までの所定の温度に設定し、電気オーブン1の外部からマイクロメータ12により歪印加用押し込み棒13を操作して、試料20に所定の歪を印加し、歪抵抗膜の抵抗を測定する。このような操作を各温度で行い、各温度で得られた抵抗変化率を別途100℃で測定したゲージ率で校正し、高温でのゲージ率を求める。これにより、高温でのゲージ率を正確に求めることができる。 When measuring the gauge ratio at a high temperature with such a high temperature strain application electric resistance measuring device, the temperature inside the electric oven 1 is set to a predetermined temperature up to about 800 ° C., and the micrometer 12 is measured from the outside of the electric oven 1. The strain applying push rod 13 is operated to apply a predetermined strain to the sample 20 and measure the resistance of the strain resistance film. Such an operation is performed at each temperature, and the resistance change rate obtained at each temperature is calibrated with a gauge rate separately measured at 100 ° C. to obtain a gauge rate at a high temperature. This makes it possible to accurately determine the gauge rate at high temperatures.

次に、本発明の歪抵抗膜および歪センサの製造方法について説明する。
本発明では、基板上に歪抵抗膜として上述したCr−N−Al薄膜を成膜した後、300℃以上700℃以下の温度で熱処理を施す。この際の熱処理は、大気中で30分以上4時間以下の期間施すことが好ましい。
Next, a method for manufacturing the strain resistance film and the strain sensor of the present invention will be described.
In the present invention, after forming the above-mentioned Cr—N—Al thin film as a strain resistance film on the substrate, heat treatment is performed at a temperature of 300 ° C. or higher and 700 ° C. or lower. The heat treatment at this time is preferably performed in the air for a period of 30 minutes or more and 4 hours or less.

これにより、上述したように、−50℃から300℃の温度領域に亘ってゲージ率が4以上、好ましくは6以上であり、−50℃から200℃でTCSが0±1500ppm/℃のほぼ一定のゲージ率を示し、また、−50℃から500℃で、TCRが±500ppm以内に低減調整が可能な歪センサが得られる。 As a result, as described above, the gauge ratio is 4 or more, preferably 6 or more over the temperature range of -50 ° C to 300 ° C, and the TCS is almost constant at 0 ± 1500 ppm / ° C from -50 ° C to 200 ° C. A strain sensor can be obtained that shows the gauge ratio of -50 ° C to 500 ° C and can reduce and adjust the TCR within ± 500 ppm.

また、400℃以下の温度領域においては長時間その温度に保持しても抵抗変化が極めて小さい、良好な抵抗の安定性も得ることができる。 Further, in the temperature range of 400 ° C. or lower, even if the temperature is maintained for a long time, the resistance change is extremely small, and good resistance stability can be obtained.

このように大気中の熱処理によって表面保護膜が形成される。この表面保護膜は、ほぼCrであり、典型的にはCrおよび不可避的不純物からなるものを挙げることができる。このような表面保護膜によって、高温でも膜中への酸素の侵入を抑制することができる。 In this way, the surface protective film is formed by the heat treatment in the atmosphere. This surface protective film is substantially Cr 2 O 3 , and typically includes one composed of Cr 2 O 3 and unavoidable impurities. With such a surface protective film, the invasion of oxygen into the film can be suppressed even at a high temperature.

本発明において、Cr−N−Al薄膜を成膜する基材(起歪構造体)としては、耐熱性が良好な絶縁性セラミックスであるアルミナを好適に用いることができる。また、アルミナに限らず、他の種々のセラミックスを用いることもできる。さらに、基材としてステンレス鋼(SUS)等、種々の金属板に絶縁コートを施したものを用いることもできる。 In the present invention, as a base material (distortion-causing structure) for forming a Cr—N—Al thin film, alumina, which is an insulating ceramic having good heat resistance, can be preferably used. Further, not limited to alumina, various other ceramics can also be used. Further, as the base material, various metal plates such as stainless steel (SUS) coated with an insulating coating can also be used.

また、Cr−N−Al薄膜を成膜する手法は特に限定されないが、微量の窒素ガスの雰囲気中でスパッタリングを行う反応性スパッタリングが好ましく、スパッタリングとしては特に高周波スパッタリングが好ましい。高周波スパッタリング装置としてはマグネトロン方式のものが好適である。高周波スパッタリングの際のガス圧は、16mTorr(2.13Pa)以下、例えば5mTorr(0.67Pa)の低圧で行うことが好ましい。 The method for forming the Cr—N—Al thin film is not particularly limited, but reactive sputtering in which sputtering is performed in an atmosphere of a trace amount of nitrogen gas is preferable, and high frequency sputtering is particularly preferable as the sputtering. As the high-frequency sputtering apparatus, a magnetron type apparatus is preferable. The gas pressure during high-frequency sputtering is preferably 16 mTorr (2.13 Pa) or less, for example, a low pressure of 5 mTorr (0.67 Pa).

この範囲よりも高圧、例えば20mTorr(2.67Pa)で高周波スパッタリングを行うと、粗い柱状晶が発達しやすくなり、柱状晶の周囲に酸素を含む明確な幅を持つ粒界が存在するようになる。これに対し、ガス圧を16mTorr(2.13Pa)以下、例えば5mTorr(0.67Pa)にすることにより、膜組織が緻密であり、酸素を含む明確な粒界が存在せず、より良好な特性を得ることができる。 When high-frequency sputtering is performed at a pressure higher than this range, for example, 20 mTorr (2.67 Pa), coarse columnar crystals are likely to develop, and grain boundaries having a clear width containing oxygen are present around the columnar crystals. .. On the other hand, by setting the gas pressure to 16 mTorr (2.13 Pa) or less, for example, 5 mTorr (0.67 Pa), the film structure is dense, there is no clear grain boundary containing oxygen, and better characteristics are obtained. Can be obtained.

歪抵抗膜として用いる薄膜のパターンとしては、歪センサとして通常用いるパターンでよく、例えば格子状パターンを用いることができる。また、高周波スパッタリングに用いるターゲットとしては高純度のCr円盤にAlのチップを所定個数貼り付けた複合ターゲットでもよいが、予め所定組成のCr−Alに調製された合金ターゲットを用いてもよい。 As the pattern of the thin film used as the strain resistance film, a pattern usually used as a strain sensor may be used, and for example, a grid pattern can be used. The target used for high-frequency sputtering may be a composite target in which a predetermined number of Al chips are attached to a high-purity Cr disk, or an alloy target prepared in advance for Cr—Al having a predetermined composition may be used.

歪センサは、上述したCr−N−Al薄膜からなる歪抵抗膜を歪材料として歪構造体上に形成することにより得られる。 The strain sensor is obtained by forming a strain resistance film made of the above-mentioned Cr—N—Al thin film on the strain structure as a strain material.

以下、本発明の実施例について説明する。
ここでは、まず、以下に示す製造条件により、基材(起歪構造体)としてのアルミナ基板上に、高周波スパッタリングにより、格子状パターンのCr−N(N:8.5at.%)薄膜を成膜し、その後、図3とは別の熱処理装置により試料を大気中500℃で0.5時間の熱処理を施した後、図3の装置により500℃までの温度範囲におけるゲージ率を測定した。
Hereinafter, examples of the present invention will be described.
Here, first, a Cr—N (N: 8.5 at.%) Thin film having a lattice pattern is formed on an alumina substrate as a base material (distortion structure) by high-frequency sputtering under the production conditions shown below. After the film was formed, the sample was heat-treated in the air at 500 ° C. for 0.5 hours using a heat treatment device different from that shown in FIG. 3, and then the gauge ratio in the temperature range up to 500 ° C. was measured by the device shown in FIG.

<製造条件>
1.成膜方法:Arガスと微量の窒素ガスの雰囲気中でスパッタリングを行う反応性スパッタリング法
2.成膜装置:マグネトロン方式の高周波スパッタリング装置を使用
3・ターゲット:公称純度99.9%で直径75.5mmのCr円盤
4.基板:純度99.9%、厚さ0.1mmのアルミナ板
5・成膜条件
・成膜真空度(背景真空度):1×10−5Pa
・ターゲット−基板間距離(T−S距離):43mm
・スパッタガス圧:5mTorr(0.67Pa)
・スパッタガス総流量:5sccm
・窒素ガス流量比(N/(Ar+N)):0.06%
・入力電力:10W
・基板温度:20℃水冷
6.薄膜歪センサ(歪ゲージ)素子のパターニングおよび熱処理等
・受感部形状:8回の折り返しからなる格子状
・格子の線幅および間隔:線幅0.04mm、間隔0.05mm
・格子長さ:1mm
・薄膜の厚さ:約100nm
・パターン形状:フォトリソグラフィー技術とCrエッチング液による腐食整形技術を利用
・熱処理:大気中において所定の温度で30分間保持
・電極形成:センサ薄膜の所定位置にAu/Ni/Cr積層薄膜をリフトオフ法で重ねて形成
・評価用素子の切り出し:ダイシング装置を用いて素子を個別に切り出し
<Manufacturing conditions>
1. 1. Film formation method: Reactive sputtering method in which sputtering is performed in an atmosphere of Ar gas and a small amount of nitrogen gas. Film forming equipment: Uses magnetron type high frequency sputtering equipment 3. Target: Cr disk with nominal purity of 99.9% and diameter of 75.5 mm 4. Substrate: Alumina plate with purity 99.9% and thickness 0.1 mm 5. Film formation conditions-Film film vacuum (background vacuum): 1 x 10-5 Pa
-Target-board distance (TS distance): 43 mm
・ Sputter gas pressure: 5mTorr (0.67Pa)
・ Total flow rate of spatter gas: 5 sccm
-Nitrogen gas flow rate ratio (N 2 / (Ar + N 2 )): 0.06%
・ Input power: 10W
-Substrate temperature: 20 ° C water cooling 6. Patterning and heat treatment of thin film strain sensor (strain gauge) elements ・ Sensitive part shape: Lattice consisting of 8 folds ・ Lattice line width and spacing: Line width 0.04 mm, spacing 0.05 mm
・ Lattice length: 1 mm
-Thin film thickness: Approximately 100 nm
-Pattern shape: Utilizes photolithography technology and corrosion shaping technology using Cr etching solution-Heat treatment: Holds at a predetermined temperature in the air for 30 minutes-Electrode formation: Lift-off method for Au / Ni / Cr laminated thin film at a predetermined position on the sensor thin film・ Cut out the evaluation element: Cut out the element individually using a dicing device.

ゲージ率の測定に際しては、試料を測定台の所定の位置にセットし、各温度に保持した状態で、図3の装置のマイクロメータにより歪印加用押し込み棒を操作して、試料に図4のシーケンスで約0.05%の歪を印加する曲げ試験を行い、450℃までの各温度において抵抗測定を行った。各温度で得られた抵抗変化率を、別途100℃で測定したゲージ率で校正し、各温度でのゲージ率を求めた。また、スパッタリングの際のガスをArのみとした以外は同様にして格子状パターンのCr膜を成膜し、同様にして、各温度で得られた抵抗変化率に基づいて各温度でのゲージ率を求めた。 When measuring the gauge ratio, the sample is set at a predetermined position on the measuring table, and the sample is held at each temperature by operating the strain applying push rod with the micrometer of the device of FIG. A bending test was performed in which a strain of about 0.05% was applied in the sequence, and resistance was measured at each temperature up to 450 ° C. The resistance change rate obtained at each temperature was calibrated with a gauge rate separately measured at 100 ° C., and the gauge rate at each temperature was obtained. Further, a Cr film having a grid pattern is formed in the same manner except that the gas used for sputtering is only Ar, and in the same manner, the gauge rate at each temperature is based on the resistance change rate obtained at each temperature. Asked.

図5はCr薄膜およびCr−N薄膜の、測定温度とゲージ率および抵抗値との関係を示す図である。この図に示すように、Cr膜およびCr−N薄膜のいずれも、100℃を超えると急激にゲージ率が低減することが確認された。また、抵抗値の変化からCr薄膜およびCr−N薄膜のネール温度は200℃付近であることが確認された。 FIG. 5 is a diagram showing the relationship between the measured temperature, the gauge ratio, and the resistance value of the Cr thin film and the Cr—N thin film. As shown in this figure, it was confirmed that the gauge ratio of both the Cr film and the Cr—N thin film sharply decreased when the temperature exceeded 100 ° C. Further, from the change in the resistance value, it was confirmed that the Néel temperature of the Cr thin film and the Cr—N thin film was around 200 ° C.

次に、ターゲットとして、公称純度99.9%で直径75.5mmのCr円盤上に5×5mm大で厚さ1mmのAlチップを乗せた複合ターゲットを用い、チップ数nを0〜16の間で変化させて、上記製造条件で、基材(起歪構造体)としてのアルミナ基板上に、高周波スパッタリングにより、Cr−N:Al(n)薄膜を成膜した。なお、後述する図24に示すように、Alチップの枚数nとAl量x(at%)との間には、およそx=1.56nの関係がある。なお、図24はEPMA(XDX)を用いて測定した値であり、2〜3%程度の誤差を含むものである。 Next, as a target, a composite target in which a 5 × 5 mm 2 large Al chip having a thickness of 1 mm is placed on a Cr disk having a nominal purity of 99.9% and a diameter of 75.5 mm is used, and the number of chips n is 0 to 16. A Cr—N: Al (n) thin film was formed on an alumina substrate as a base material (distortion-causing structure) by high-frequency sputtering under the above-mentioned production conditions. As shown in FIG. 24, which will be described later, there is a relationship of about x = 1.56n between the number n of Al chips and the amount of Al x (at%). Note that FIG. 24 is a value measured using EPMA (XDX) and includes an error of about 2 to 3%.

nを0、4、8、12、16(Al量は、それぞれ、およそ0、6.24、12.48、18.72、24.96at%)として成膜した試料について、図3とは別の熱処理装置により、試料を大気中500℃で0.5時間の熱処理を施した後、500℃までの温度範囲におけるゲージ率を測定した。 The sample formed with n set to 0, 4, 8, 12, 16 (Al amounts are about 0, 6.24, 12.48, 18.72, 24.96 at%, respectively) is different from FIG. The sample was heat-treated in the air at 500 ° C. for 0.5 hours, and then the gauge ratio in the temperature range up to 500 ° C. was measured.

ゲージ率の測定に際しては、試料を測定台の所定の位置にセットし、各温度に保持した状態で、図3の装置のマイクロメータにより歪印加用押し込み棒を操作して、試料に図4のシーケンスで約0.05%の歪を印加する曲げ試験を行い、450℃または500℃までの各温度において抵抗測定を行った。各温度で得られた抵抗変化率を、別途100℃で測定したゲージ率で校正し、各温度でのゲージ率を求めた。 When measuring the gauge ratio, the sample is set at a predetermined position on the measuring table, and the sample is held at each temperature by operating the strain applying push rod with the micrometer of the device of FIG. A bending test was performed in which a strain of about 0.05% was applied in the sequence, and resistance was measured at each temperature up to 450 ° C. or 500 ° C. The resistance change rate obtained at each temperature was calibrated with a gauge rate separately measured at 100 ° C., and the gauge rate at each temperature was obtained.

その結果を図6に示す。この図に示すように、Al量の増加(Alチップ数nの増加)にともなって、ゲージ率の大きい領域が高温側に拡大する傾向が得られた。特に、Alチップ数nが12〜16の場合に、−50〜500℃まででゲージ率が7以上のほぼ一様な値を示すことが確認された。また、Alチップ数が8の場合は、450℃でゲージ率がわずかに低下しているものの、−50〜400℃まではほぼ一様であり、ゲージ率の値は7以上であった。また、Alチップ数が4の場合は、200℃まではほぼ一様なゲージ率を示すが、200℃を超えるとゲージ率が低下し、300℃以下ではゲージ率4以上であるものの、300℃を超えるとゲージ率は4よりも低い値となることが確認された。それはAl量が少ないためにネール温度の上昇も小さかったためである。このことから、Alチップ数が8程度以上、Al量がおよそ10at%以上の場合がより好ましいことが確認された。 The result is shown in FIG. As shown in this figure, as the amount of Al increased (the number of Al chips n increased), the region having a large gauge ratio tended to expand to the high temperature side. In particular, it was confirmed that when the number of Al chips n is 12 to 16, the gauge ratio shows a substantially uniform value of 7 or more at -50 to 500 ° C. When the number of Al chips was 8, the gauge ratio was slightly reduced at 450 ° C., but was almost uniform from −50 to 400 ° C., and the gauge ratio value was 7 or more. Further, when the number of Al chips is 4, the gauge ratio is almost uniform up to 200 ° C., but when it exceeds 200 ° C., the gauge ratio decreases, and when it is 300 ° C. or lower, the gauge ratio is 4 or more, but 300 ° C. It was confirmed that the gauge rate becomes a value lower than 4 when the value exceeds. This is because the increase in the Neel temperature was small because the amount of Al was small. From this, it was confirmed that the case where the number of Al chips is about 8 or more and the amount of Al is about 10 at% or more is more preferable.

図7は、Alチップ数が0、4、8の場合の抵抗値の昇降温依存性を示す図であるが、Alチップ数が8の場合のネール温度は測定温度の上限よりも高く500℃を超える値であると考えられ、Al添加によりネール温度の高温シフトが確認された。図6のAl添加によりゲージ率が大きい領域が高温に拡大する傾向は、ネール温度の上昇によるものと考えられる。 FIG. 7 is a diagram showing the temperature dependence of the resistance value when the number of Al chips is 0, 4, and 8. However, when the number of Al chips is 8, the Neel temperature is higher than the upper limit of the measurement temperature and is 500 ° C. It was considered that the value exceeded the above value, and a high temperature shift of the Néel temperature was confirmed by adding Al. The tendency for the region with a large gauge ratio to expand to a high temperature due to the addition of Al in FIG. 6 is considered to be due to an increase in the Néel temperature.

次に、Alチップ数が8の場合について、上述した大気中500℃で0.5時間の熱処理を施した試料と、大気中700℃で0.5時間の熱処理を施した試料についてゲージ率を比較した。なお、700℃のものについては、650℃までのゲージ率を求めた。その結果を図8に示す。この図に示すように、熱処理温度が700℃の試料では、250℃以上において、ゲージ率が低下する傾向にあるが、それは後述するように、700℃の熱処理によって酸素が膜中に取り込まれ、そのためネール温度が低下したことによる。それでも、300℃付近まではゲージ率4以上を維持していることが確認された。 Next, in the case where the number of Al chips is 8, the gauge ratios of the above-mentioned sample heat-treated at 500 ° C. for 0.5 hours and the sample heat-treated at 700 ° C. for 0.5 hours in the air are measured. Compared. For 700 ° C, the gauge rate up to 650 ° C was determined. The result is shown in FIG. As shown in this figure, in a sample having a heat treatment temperature of 700 ° C., the gauge ratio tends to decrease at 250 ° C. or higher, but as will be described later, oxygen is taken into the membrane by the heat treatment at 700 ° C. Therefore, the nail temperature has dropped. Even so, it was confirmed that the gauge rate was maintained at 4 or higher up to around 300 ° C.

次に、上述したAlチップ数nを0〜16として成膜した後、大気中500℃で0.5時間の熱処理を施した試料について、感度温度係数(TCS)を求めた。図9は、その際の測定温度とTCSとの関係を示す図である。なお、各温度のプロットは、その温度からその温度+50℃でのTCSを示す。つまり、150℃のプロットは、150〜200℃でのTCSを示す。この図に示すように、n=4では、200℃を超えるとTCSが±1500ppm/℃の範囲を超えたが、n=8では400℃まで、n=12〜16では500℃まで、TCSが±1500ppm/℃以内であった。 Next, the temperature coefficient of sensitivity (TCS) was determined for a sample that had been formed with the above-mentioned number n of Al chips set to 0 to 16 and then heat-treated at 500 ° C. for 0.5 hours in the air. FIG. 9 is a diagram showing the relationship between the measured temperature and TCS at that time. The plot of each temperature shows the TCS at that temperature + 50 ° C. from that temperature. That is, the 150 ° C. plot shows TCS at 150-200 ° C. As shown in this figure, at n = 4, the TCS exceeded the range of ± 1500 ppm / ° C. above 200 ° C., but at n = 8, it was up to 400 ° C., and at n = 12-16, the TCS was up to 500 ° C. It was within ± 1500 ppm / ° C.

次に、Alチップ数が8の場合について、上述した大気中500℃で0.5時間の熱処理を施した試料と、大気中700℃で0.5時間の熱処理を施した試料について各温度のTCSを求めた。なお、700℃のものについては、650℃までのTCSを求めた。その結果を図10に示す。熱処理温度が700℃の試料では、250℃までTCSが±1500ppm/℃の範囲内であった。 Next, in the case where the number of Al chips is 8, the above-mentioned sample that has been heat-treated at 500 ° C. for 0.5 hours in the air and the sample that has been heat-treated at 700 ° C. for 0.5 hours in the air have different temperatures. I asked for TCS. For those at 700 ° C, TCS up to 650 ° C was determined. The result is shown in FIG. In the sample having a heat treatment temperature of 700 ° C., the TCS was within the range of ± 1500 ppm / ° C. up to 250 ° C.

次に、上述したCr円盤上にn個のAlチップを乗せた複合ターゲットを用い、nを0〜16の間で変化させ、上記製造条件で成膜後、種々の熱処理条件で熱処理した場合について、室温近傍の抵抗温度係数(TCR)を測定した。図11は、300℃、500℃、700℃で熱処理した場合のAlチップの数nとTCRの関係を示す図である。 Next, in the case where a composite target in which n Al chips are placed on the above-mentioned Cr disk is used, n is changed between 0 and 16, the film is formed under the above-mentioned production conditions, and then heat-treated under various heat treatment conditions. , The temperature coefficient of resistance (TCR) near room temperature was measured. FIG. 11 is a diagram showing the relationship between the number n of Al chips and the TCR when heat-treated at 300 ° C., 500 ° C., and 700 ° C.

図11に示すように、Cr−N薄膜にAlを添加した場合でも、Cr−N薄膜と同様、TCRはas−depo.で負の値をとり、熱処理で正方向に変化することが確認された。また、Al量の増加にともなってTCRが減少し、負に大きな値を示すことが確認された。このことから、Cr−N−Al薄膜の組成(N量およびAl量)と熱処理温度によりTCRを制御可能であることが明らかとなった。また、いずれの熱処理温度においても、室温でのTCRがほぼゼロの試料が存在することが確認された。 As shown in FIG. 11, even when Al is added to the Cr—N thin film, the TCR is as-depo. It took a negative value in, and it was confirmed that it changed in the positive direction by heat treatment. Further, it was confirmed that the TCR decreased with the increase in the amount of Al and showed a negatively large value. From this, it was clarified that the TCR can be controlled by the composition (N amount and Al amount) of the Cr—N—Al thin film and the heat treatment temperature. Further, it was confirmed that there was a sample having a TCR of almost zero at room temperature at any heat treatment temperature.

次に、上記Alチップの数nを0〜16の間で変化させた複合ターゲットを用いて上記製造条件で成膜後、大気中500℃で0.5時間の熱処理を施した試料について、0〜500℃または0〜450℃の範囲の抵抗値を求めた。その結果を図12に示す。この図に示すように、Alチップの数nが増加するに従って、温度上昇に対する抵抗値の変化(低下)が大きくなることが確認された。 Next, for a sample obtained by forming a film under the above manufacturing conditions using a composite target in which the number n of the Al chips was changed between 0 and 16 and then heat-treating at 500 ° C. in the air for 0.5 hours, 0 The resistance value in the range of ~ 500 ° C. or 0 to 450 ° C. was determined. The result is shown in FIG. As shown in this figure, it was confirmed that as the number n of Al chips increases, the change (decrease) in the resistance value with respect to the temperature rise increases.

次に、Alチップ数が8の場合について、上述した大気中500℃で0.5時間の熱処理を施した試料と、大気中700℃で0.5時間の熱処理を施した試料について抵抗値の温度変化を比較した。なお、700℃のものについては、650℃までの抵抗値を求めた。その結果を図13に示す。この図に示すように、熱処理温度が500℃の場合は、測定温度の上昇にともなって抵抗値が比較的大きく低下しているが、熱処理温度が700℃の場合は、測定温度による抵抗値の変化が小さいことが確認された。 Next, in the case where the number of Al chips is 8, the resistance values of the above-mentioned sample that has been heat-treated at 500 ° C. for 0.5 hours and the sample that has been heat-treated at 700 ° C. for 0.5 hours in the air have resistance values. The temperature changes were compared. For 700 ° C., the resistance value up to 650 ° C. was determined. The result is shown in FIG. As shown in this figure, when the heat treatment temperature is 500 ° C., the resistance value decreases relatively significantly as the measurement temperature rises, but when the heat treatment temperature is 700 ° C., the resistance value due to the measurement temperature It was confirmed that the change was small.

次に、上記Alチップの数nを0〜16の間で変化させた複合ターゲットを用いて上記製造条件で成膜後、大気中500℃で0.5時間の熱処理を施した試料について、100〜500℃または100〜450℃の範囲のTCRを求めた。その結果を図14に示す。なお、各温度のプロットは、その温度からその温度+50℃でのTCRを示す。つまり、150℃のプロットは、150〜200℃でのTCRを示す。この図に示すように、Alチップ数0の試料は、100〜450℃の範囲において、TCRが+500ppm/℃を超えているのに対し、Alチップ数の増加(Al量の増加)にともなって、TCRがマイナス側にシフトした。Alチップ数4の試料は、100〜500℃の範囲でTCRがほぼ0となった。また、Alチップ数が8の試料は、100〜450℃の範囲でTCRが±1000ppm/℃以内であった。一方、Alチップ数が12、16の試料は、100℃〜500℃の範囲でTCRが−1000ppm/℃よりも小さい(不の絶対値が大きい)値となった。このことから、Al量を調整することにより、500℃までの温度範囲で、±1000ppm/℃以内、さらには±500ppm/℃以内のTCRが得られることが確認された。 Next, for a sample obtained by forming a film under the above manufacturing conditions using a composite target in which the number n of the Al chips was changed between 0 and 16 and then heat-treating at 500 ° C. in the air for 0.5 hours, 100 A TCR in the range of ~ 500 ° C. or 100 to 450 ° C. was determined. The result is shown in FIG. The plot of each temperature shows the TCR from that temperature at that temperature + 50 ° C. That is, the 150 ° C. plot shows the TCR at 150-200 ° C. As shown in this figure, the sample having 0 Al chips has a TCR exceeding + 500 ppm / ° C in the range of 100 to 450 ° C., whereas the sample has an increase in the number of Al chips (increase in the amount of Al). , TCR shifted to the minus side. The sample having 4 Al chips had a TCR of almost 0 in the range of 100 to 500 ° C. The sample having 8 Al chips had a TCR of ± 1000 ppm / ° C. in the range of 100 to 450 ° C. On the other hand, in the samples having 12 and 16 Al chips, the TCR was smaller than −1000 ppm / ° C. (the absolute value of non-absolute value was large) in the range of 100 ° C. to 500 ° C. From this, it was confirmed that by adjusting the amount of Al, a TCR within ± 1000 ppm / ° C. and further within ± 500 ppm / ° C. can be obtained in the temperature range up to 500 ° C.

次に、Alチップ数が8の場合について、上述した大気中500℃で0.5時間の熱処理を施した試料と、大気中700℃で0.5時間の熱処理を施した試料について各温度のTCRを求めた。なお、700℃のものについては、650℃までのTCRを求めた。その結果を図15に示す。この図に示すように、熱処理温度が500℃の試料は、TCRが−500ppm/℃よりも小さい値であったのに対し、熱処理温度が700℃の試料は、500℃まで、TCRが±500ppm/℃以内であった。このことから、熱処理によってTCRを調整することができ、±500ppm/℃以内にすることが可能であることが確認された。 Next, in the case where the number of Al chips is 8, the above-mentioned sample that has been heat-treated at 500 ° C. for 0.5 hours in the air and the sample that has been heat-treated at 700 ° C. for 0.5 hours in the air have different temperatures. The TCR was calculated. For 700 ° C, TCR up to 650 ° C was determined. The result is shown in FIG. As shown in this figure, the sample having a heat treatment temperature of 500 ° C. had a TCR of less than −500 ppm / ° C., whereas the sample having a heat treatment temperature of 700 ° C. had a TCR of ± 500 ppm up to 500 ° C. It was within / ° C. From this, it was confirmed that the TCR can be adjusted by heat treatment and can be kept within ± 500 ppm / ° C.

次に、ターゲットとして、同様にAlチップn個を乗せた複合ターゲットを用い、nの数を0〜16の間で変化させて、上記製造条件で成膜後、種々の熱処理条件で熱処理した場合について、室温近傍のTCS、ゲージ率を測定した。図16はAlチップ数とTCSとの関係を示す図、図17はAlチップ数とゲージ率との関係を示す図である。 Next, when a composite target on which n Al chips are similarly mounted is used as the target, the number of n is changed between 0 and 16, and the film is formed under the above manufacturing conditions and then heat-treated under various heat treatment conditions. The TCS and gauge ratio near room temperature were measured. FIG. 16 is a diagram showing the relationship between the number of Al chips and TCS, and FIG. 17 is a diagram showing the relationship between the number of Al chips and the gauge ratio.

図16に示すように、Alチップ数nが2〜16において、300℃以上の熱処理で、TCSが−1500〜+1000ppm/℃の範囲内の良好な値を示すことが確認された。 As shown in FIG. 16, it was confirmed that when the number of Al chips n was 2 to 16, the TCS showed a good value in the range of -1500 to + 1000 ppm / ° C. by the heat treatment at 300 ° C. or higher.

さらに、図17に示すように、Alチップ数nが2〜16において、300℃以上の熱処理で、ゲージ率4以上の、従来用いられている歪ゲージよりも大きな値を示すことが確認された。 Further, as shown in FIG. 17, it was confirmed that when the number of Al chips n is 2 to 16, the heat treatment at 300 ° C. or higher exhibits a gauge ratio of 4 or more, which is larger than that of the conventionally used strain gauge. ..

次に、Al量を変化させたCr−N−Al薄膜の抵抗の安定性について試験を行った。図18〜22は、各測定温度における抵抗変化率(ΔR/R)を示す図であり、図18はAlチップ個数n=0(Cr−N:Al(0)薄膜)の場合、図19はAlチップ個数n=4(Cr−N:Al(4)薄膜)の場合、図20はAlチップ数n=8(Cr−N:Al(8)薄膜)の場合、図21はAlチップ数n=12(Cr−N:Al(12)薄膜)の場合、図22はAlチップ数n=16(Cr−N:Al(16)薄膜)の場合である。抵抗変化率は、図4に示すように、曲げを含む30分保持前後の抵抗値から求めた。なお、成膜後の熱処理は、大気中500℃で0.5時間とした。 Next, the stability of the resistance of the Cr—N—Al thin film in which the amount of Al was changed was tested. 18 to 22 are diagrams showing the resistance change rate (ΔR / R 0 ) at each measurement temperature, and FIG. 18 is FIG. 19 when the number of Al chips is n = 0 (Cr−N: Al (0) thin film). Is the number of Al chips n = 4 (Cr—N: Al (4) thin film), FIG. 20 shows the number of Al chips n = 8 (Cr—N: Al (8) thin film), and FIG. 21 shows the number of Al chips. In the case of n = 12 (Cr—N: Al (12) thin film), FIG. 22 shows the case of the number of Al chips n = 16 (Cr—N: Al (16) thin film). As shown in FIG. 4, the resistance change rate was obtained from the resistance values before and after holding for 30 minutes including bending. The heat treatment after the film formation was carried out at 500 ° C. in the air for 0.5 hours.

これらの図に示すように、大気中500℃で0.5時間の熱処理によって、Alチップ数n=8までは400℃まで抵抗変化率が±0.02%以内の高い安定性を示すことが確認された。これに対し、Alチップ数n=12、16の試料は、安定性が多少低下した。しかしその低下は、図11および図14に示されているように、n=12および16の試料のTCRの絶対値が大きいため、図3の電気オーブンおよび室内の空調の温度コントロールの、それほど大きくはないが生じる変動によって生起したものである。測定温度による変動であれば、後述の図23のように一方向に値がシフトしていく挙動を示すはずであるが、図18から22において400℃までにそのようなシフトは見られず、バラツキ的な変化を示すことから、そのように判断できる。この結果は、TCRの低減がいかに重要であるかを示唆するものであり、それを含んでもなお、変化率は±0.05%以内と良好である。 As shown in these figures, it is possible to show high stability with a resistance change rate of ± 0.02% or less up to 400 ° C. up to the number of Al chips n = 8 by heat treatment at 500 ° C. for 0.5 hours in the atmosphere. confirmed. On the other hand, the stability of the samples having Al chips n = 12 and 16 was slightly lowered. However, the decrease is not so large in the temperature control of the electric oven and indoor air conditioning in FIG. 3 due to the large absolute value of the TCR of the samples n = 12 and 16, as shown in FIGS. 11 and 14. It is caused by fluctuations that occur, though not. If it fluctuates due to the measurement temperature, it should show the behavior of shifting the value in one direction as shown in FIG. 23 described later, but such a shift is not seen from FIG. 18 to 22 to 400 ° C. It can be judged that way because it shows various changes. This result suggests how important the reduction of TCR is, and even if it is included, the rate of change is as good as ± 0.05% or less.

次に、Alチップ数n=8のCr−N:Al(8)薄膜について、成膜後の熱処理を大気中700℃で0.5時間として、熱処理後同様に各測定温度で曲げを含む30分間保持による試験を行い、保持前後の抵抗変化率を求めた。図23はその際の各測定温度における抵抗変化率(ΔR/R)を示す図である。この図に示すように、Cr−N:Al(8)薄膜は、700℃で熱処理することにより、500℃とより高温まで抵抗変化率が±0.02%以内の高い安定性を示すことが確認された。 Next, for the Cr—N: Al (8) thin film having an Al chip number n = 8, the heat treatment after film formation is set to 0.5 hours at 700 ° C. in the air, and bending is included at each measurement temperature in the same manner as after the heat treatment 30. A test was conducted by holding for a minute, and the rate of change in resistance before and after holding was determined. FIG. 23 is a diagram showing the resistance change rate (ΔR / R 0) at each measured temperature at that time. As shown in this figure, the Cr—N: Al (8) thin film can exhibit high stability with a resistance change rate of ± 0.02% or less up to a higher temperature of 500 ° C. by heat treatment at 700 ° C. confirmed.

なお、図24に、上述した製造条件のときの、Alチップ数nと、Al量(at.%)との関係を示す。上述したとおり、Alチップ数nとAl濃度x(at%)との間には、およそx=1.56nの関係がある。 Note that FIG. 24 shows the relationship between the number of Al chips n and the amount of Al (at.%) Under the above-mentioned manufacturing conditions. As described above, there is a relationship of approximately x = 1.56n between the number of Al chips n and the Al concentration x (at%).

次に、以上の条件で製造した試料と、スパッタガス圧を5mTorr(0.67Pa)から20mTorr(2.67Pa)に変更し、さらに、それにともなって、成膜方法をコンベンショナル方式、ターゲット直径を101.6mm、スパッタガス総流量を20sccm、入力電力を100Wに変更した以外は同様の条件で製造した試料とについてミクロ組織を観察した。 Next, the sample produced under the above conditions and the sputtering gas pressure were changed from 5 mTorr (0.67 Pa) to 20 mTorr (2.67 Pa), and accordingly, the film formation method was a conventional method and the target diameter was 101. The microstructure was observed with the sample produced under the same conditions except that the total flow rate of the sputter gas was changed to .6 mm, the total flow rate of the sputtering gas was changed to 20 sccm, and the input power was changed to 100 W.

図25は、Alチップ数n=4で成膜した後、大気中500℃で0.5時間の熱処理を施した試料を示すSEM写真であり、図26は、Alチップ数n=8で成膜した後、大気中500℃で0.5時間の熱処理を施した試料を示すSEM写真であり、図27は、Alチップ数n=8で成膜した後、大気中500℃で0.5時間の熱処理を施した試料を示すSEM写真である。いずれもスパッタガス圧が20mTorrと5mTorrの場合を比較して示す。また、図28は、Alチップ数8で成膜した後、大気中700℃で0.5時間の熱処理を施した試料を示すSEM写真であり、スパッタガス圧が20mTorrと5mTorrの場合を比較して示すものである。また、図29は、Alチップ数n=8、Alチップ数n=16でスパッタガス圧5mTorrで成膜した場合の、成膜まま(as−deposited)の試料を示すSEM写真である。さらに、図30は、Alチップ数n=8で成膜した場合の、as−depositedの試料、大気中500℃で0.5時間の熱処理を施した試料、および大気中700℃で0.5時間の熱処理を施した試料を示すTEM写真である。 FIG. 25 is an SEM photograph showing a sample obtained by forming a film with the number of Al chips n = 4 and then heat-treating the sample in the air at 500 ° C. for 0.5 hours, and FIG. 26 is a sample formed with the number of Al chips n = 8. FIG. 27 is an SEM photograph showing a sample which has been heat-treated at 500 ° C. in the air for 0.5 hours after forming a film, and FIG. 27 shows a film formed with an Al chip number n = 8 and then 0.5 at 500 ° C. in the air. 6 is an SEM photograph showing a sample that has been heat-treated for hours. In each case, the cases where the sputter gas pressure is 20 mTorr and 5 mTorr are compared and shown. Further, FIG. 28 is an SEM photograph showing a sample which has been heat-treated at 700 ° C. for 0.5 hours in the air after forming a film with 8 Al chips, and compares the cases where the sputtering gas pressures are 20 mTorr and 5 mTorr. Is shown. Further, FIG. 29 is an SEM photograph showing a sample as-deposited when a film is formed with an Al chip number n = 8 and an Al chip number n = 16 at a sputtering gas pressure of 5 mTorr. Further, FIG. 30 shows an as-deposited sample when the film was formed with the number of Al chips n = 8, a sample heat-treated at 500 ° C. in the air for 0.5 hours, and 0.5 at 700 ° C. in the air. 6 is a TEM photograph showing a sample that has been heat-treated for hours.

これらTEM写真に示すように、条件にかかわらず、スパッタガス圧が20mTorrで成膜した試料は、粗い柱状晶が発達しているのに対し、スパッタガス圧を5mTorrとした試料は、こちらも柱状晶ではあるが、膜組織が緻密であることが確認された。この膜組織の違いにより、スパッタガス圧を5mTorrとした試料のほうが、スパッタガス圧が20mTorrで成膜した試料よりも、200℃以上でのゲージ率が2倍以上上昇した。 As shown in these TEM photographs, regardless of the conditions, the sample formed with a sputter gas pressure of 20 mTorr has coarse columnar crystals, whereas the sample with a sputter gas pressure of 5 mTorr also has columns. Although it was a crystal, it was confirmed that the membrane structure was dense. Due to this difference in film structure, the gauge ratio at 200 ° C. or higher was more than doubled in the sample having a sputter gas pressure of 5 mTorr than that in the sample formed with a sputter gas pressure of 20 mTorr.

また、図29のas−depositedの試料からは、緻密な柱状晶からなる組織のセンシング膜のみからなり、その上には何もないことが確認された。それに対し、500℃熱処理ではそのセンシング膜の上に薄い別の層が、700℃では厚い別の層が形成されていることがわかる。このことから、成膜時には存在しなかった別の層が、高温での熱処理によって形成され、より高温なほど厚く成長することが確認できる。後段で示す分析結果からそれらはCrからなり、センシング層の酸化を防ぐ保護層として機能するものであることが初めて明らかになった。 Further, from the as-deposited sample of FIG. 29, it was confirmed that the sample consisted only of a sensing film having a structure composed of dense columnar crystals, and nothing was on the sensing film. On the other hand, it can be seen that another thin layer is formed on the sensing film by the heat treatment at 500 ° C. and another thick layer is formed at 700 ° C. From this, it can be confirmed that another layer, which did not exist at the time of film formation, is formed by the heat treatment at a high temperature and grows thicker at a higher temperature. From the analysis results shown in the latter part, it was clarified for the first time that they consist of Cr 2 O 3 and function as a protective layer that prevents oxidation of the sensing layer.

次に、以上の条件で製造した試料と、スパッタガス圧を5mTorr(0.67Pa)から20mTorr(2.67Pa)に変更し、さらに上記と同様の一連の変更を施した以外は同様の条件で製造した試料について、それらの薄膜断面のEDX面分析を行った。 Next, the sample produced under the above conditions and the sputter gas pressure were changed from 5 mTorr (0.67 Pa) to 20 mTorr (2.67 Pa), and the same conditions were used except that the same series of changes as above were made. The prepared samples were subjected to EDX plane analysis of their thin film cross sections.

図31、図32は、いずれもAlチップ数n=8で成膜した後、大気中500℃で0.5時間の熱処理を施した試料における薄膜断面のEDX面分析結果を示す図であり、図31はスパッタガス圧が20mTorr、図32はスパッタガス圧が5mTorrである。また、図33、図34は、いずれもAlチップ数n=8で成膜した後、大気中700℃で0.5時間の熱処理を施した試料における薄膜断面のEDX面分析結果を示す図であり、図33はスパッタガス圧が20mTorr、図34はスパッタガス圧が5mTorrである。図31〜34は、いずれもHAADEF−STEM像と、各元素の面分析を示す。 31 and 32 are both views showing the EDX plane analysis result of the thin film cross section of the sample which was subjected to heat treatment at 500 ° C. for 0.5 hour in the air after forming a film with the number of Al chips n = 8. FIG. 31 shows a sputter gas pressure of 20 mTorr, and FIG. 32 shows a sputter gas pressure of 5 mTorr. In addition, FIGS. 33 and 34 are diagrams showing the results of EDX plane analysis of the thin film cross section of the sample which was subjected to heat treatment at 700 ° C. for 0.5 hour in the air after forming a film with the number of Al chips n = 8. In FIG. 33, the sputter gas pressure is 20 mTorr, and in FIG. 34, the sputter gas pressure is 5 mTorr. Figures 31 to 34 show HAADEF-STEM images and surface analysis of each element.

図31、図33に示すスパッタガス圧を20mTorrとした試料については、HAADEF−STEM像に明確な濃淡が観察され、明るい箇所にCr、暗い箇所にO(酸素)が、それぞれ対応していることかがわかる。Cr基の結晶粒の間に酸素を多く含む幅のある粒界が薄膜内全体に存在し、密でない結晶組織を呈していることがわかる。 For the samples shown in FIGS. 31 and 33 in which the sputter gas pressure was 20 mTorr, clear shades were observed in the HAADEF-STEM image, and Cr corresponded to the bright part and O (oxygen) corresponded to the dark part. I know. It can be seen that a wide grain boundary containing a large amount of oxygen exists between the crystal grains of the Cr group throughout the thin film, and exhibits a non-dense crystal structure.

図32、図34に示すスパッタガス圧を5mTorrとした試料については、HAADEF−STEM像に明確な濃淡が観察されず、薄膜内には、ほぼ一様にCrが多く、O(酸素)はあまり存在しないことがわかる。したがって幅広な粒界はなく、Crリッチな結晶粒が密に詰まった結晶組織を呈していることがわかる。 For the samples with sputter gas pressure of 5 mTorr shown in FIGS. 32 and 34, no clear shading was observed in the HAADEF-STEM image, and the thin film contained a large amount of Cr and a small amount of O (oxygen). It turns out that it does not exist. Therefore, it can be seen that there are no wide grain boundaries and the crystal structure is densely packed with Cr-rich crystal grains.

次に、Alチップ数n=8で、それぞれスパッタガス圧20mTorr、5mTorrで成膜した後、それぞれ大気中500℃、700℃で0.5時間の熱処理を施した試料について、XPSにより深さ方向の組成プロファイルを測定した。その結果を図35〜38に示す。 Next, the samples were formed with a sputter gas pressure of 20 mTorr and 5 mTorr with the number of Al chips n = 8 and then heat-treated at 500 ° C. and 700 ° C. for 0.5 hours in the air, respectively, in the depth direction by XPS. The composition profile of was measured. The results are shown in FIGS. 35-38.

図35は、スパッタガス圧20mTorrで500℃熱処理を施した試料の深さ方向の組成プロファイルを示す図であるが、薄膜中にO(酸素)が約20%も含まれており、面分析結果と良い一致を示した。左側の最表面にはCrが約40%、酸素が約60%であることから、安定なCrの酸化層が形成されていると考えられる。 FIG. 35 is a diagram showing a composition profile in the depth direction of a sample heat-treated at 500 ° C. at a sputtering gas pressure of 20 mTorr. The thin film contains about 20% of O (oxygen), and the surface analysis result. Showed a good match. Since Cr is about 40% and oxygen is about 60% on the outermost surface on the left side, it is considered that a stable Cr 2 O 3 oxide layer is formed.

図36は、スパッタガス圧5mTorrで500℃熱処理を施した試料の深さ方向の組成プロファイルを示す図であるが、薄膜中にO(酸素)は約2%程度と不可避的に含まれているだけで、こちらも面分析結果と良い一致を示した。左側の最表面には20mTorrと同様に、安定なCrの酸化層が形成され、保護膜として薄膜内部の酸化を防いでいると考えられる。 FIG. 36 is a diagram showing a composition profile in the depth direction of a sample heat-treated at 500 ° C. at a sputtering gas pressure of 5 mTorr, and O (oxygen) is inevitably contained in the thin film at about 2%. However, this also showed good agreement with the surface analysis results. Similar to 20 mTorr, a stable Cr 2 O 3 oxide layer is formed on the outermost surface on the left side, and it is considered that the protective film prevents oxidation inside the thin film.

図37は、スパッタガス圧20mTorrで700℃熱処理を施した試料の深さ方向の組成プロファイルを示す図であるが、薄膜中にO(酸素)が約25%も含まれており、面分析結果と良い一致を示した。左側の最表面にはCrが約45%、酸素が約55%と少しCrリッチではあるが、Crの厚い酸化層が形成されていると考えられる。 FIG. 37 is a diagram showing a composition profile in the depth direction of a sample heat-treated at 700 ° C. at a sputtering gas pressure of 20 mTorr. The thin film contains about 25% of O (oxygen), and the surface analysis result. Showed a good match. On the outermost surface on the left side, Cr is about 45% and oxygen is about 55%, which are slightly Cr-rich, but it is considered that a thick oxide layer of Cr 2 O 3 is formed.

図38は、スパッタガス圧5mTorrで700℃熱処理を施した試料の深さ方向の組成プロファイルを示す図であるが、薄膜中にO(酸素)は約10数%程度と、比較的多く含まれていた。700℃ではOは膜中に一様に拡散すると考えられ、そのため面分析ではよくわからなかったと思われる。左側の最表面には20mTorrと同様に、CrリッチなCrの厚い酸化層が形成されている。この酸化層はおよそ500℃以下で保護膜として薄膜内部の酸化を防いでいると考えられるが、700℃ではその効果が低下している。 FIG. 38 is a diagram showing a composition profile in the depth direction of a sample heat-treated at 700 ° C. at a sputtering gas pressure of 5 mTorr, and O (oxygen) is contained in the thin film in a relatively large amount of about 10%. Was there. At 700 ° C., O is thought to diffuse uniformly into the membrane, so it seems that it was not well understood by surface analysis. Similar to 20 mTorr, a thick oxide layer of Cr-rich Cr 2 O 3 is formed on the outermost surface on the left side. It is considered that this oxide layer prevents oxidation inside the thin film as a protective film at about 500 ° C. or lower, but the effect is reduced at 700 ° C.

次に、Alチップ数n=8でスパッタガス圧5mTorrで成膜時間を約5倍にして20mTorrの場合とほぼ同じ厚さで成膜した後、大気中500℃で0.5時間の熱処理を施した試料を作製した。 Next, the film formation time is increased about 5 times at a sputter gas pressure of 5 mTorr with the number of Al chips n = 8 to form a film with almost the same thickness as in the case of 20 mTorr, and then heat treatment is performed at 500 ° C. in the air for 0.5 hours. The subjected sample was prepared.

図39は、その試料の断面のTEM写真である。このTEM写真から、幅広の粒界が形成されることもなく、表面まで密な組織を示していることが確認され、厚さの違いの影響はないと考えられる。なお、中央の横に入った非結晶的な層は成膜途中のトラブルにより一時的に生じたものである。図40はその試料における薄膜断面のEDX面分析結果を示すが、膜厚を厚くしてもHAADEF−STEM像に明確な濃淡が観察されず、薄膜内には、ほぼ一様にCrが多く、O(酸素)があまり存在しないことが確認された。また、幅広な粒界はなく、全厚さにわたってCrリッチな結晶粒が密に詰まった結晶組織を呈していることがわかる。図41はその試料のXPSによる深さ方向の組成プロファイルを示す図であるが、薄膜中にO(酸素)は1〜2%程度と不可避的に含まれているだけで、こちらも面分析結果と良い一致を示した。やはり左側の最表面に安定なCrの酸化層が形成され、保護膜として薄膜内部の酸化を防いでいると考えられる。中央の非結晶的な層は酸素を多く含むことから、成膜時の酸素混入のトラブルが発生したと思われる。 FIG. 39 is a TEM photograph of a cross section of the sample. From this TEM photograph, it was confirmed that wide grain boundaries were not formed and the structure was dense to the surface, and it is considered that there is no influence of the difference in thickness. The amorphous layer on the side of the center was temporarily generated due to a trouble during film formation. FIG. 40 shows the EDX plane analysis result of the cross section of the thin film in the sample, but no clear shading was observed in the HAADEF-STEM image even if the film thickness was increased, and the thin film contained a large amount of Cr almost uniformly. It was confirmed that there was not much O (oxygen). Further, it can be seen that there are no wide grain boundaries and the crystal structure is densely packed with Cr-rich crystal grains over the entire thickness. FIG. 41 is a diagram showing the composition profile of the sample in the depth direction by XPS, but the thin film inevitably contains O (oxygen) of about 1 to 2%, which is also the result of surface analysis. Showed a good match. It is also considered that a stable Cr 2 O 3 oxide layer is formed on the outermost surface on the left side to prevent oxidation inside the thin film as a protective film. Since the amorphous layer in the center contains a large amount of oxygen, it is considered that a trouble of oxygen mixing during film formation occurred.

1;電気オーブン、2;窓、3;蓋部材、4;支持棒、5;測定台、6;固定部材、7;基板、8;薄膜(歪抵抗膜)、10;端子台、11;端子、12;マイクロメータ、13;歪印加用押し込み棒 1; Electric oven, 2; Window, 3; Lid member, 4; Support rod, 5; Measuring stand, 6; Fixing member, 7; Substrate, 8; Thin film (distortion resistance film), 10; Terminal block, 11; Terminal , 12; Micrometer, 13; Push rod for strain application

Claims (12)

一般式Cr100−x−yAl
(ただし、x、yは原子比率(at.%)であり、4≦x≦25、0.1≦y≦20である。)で表され、−50℃以上300℃以下の温度範囲において、ゲージ率が4以上であり、酸素を含む明確な幅を持つ粒界が存在しないことを特徴とする歪抵抗膜。
General formula Cr 100-xy Al x N y
(However, x and y are atomic ratios (at.%) And are represented by 4 ≦ x ≦ 25 and 0.1 ≦ y ≦ 20), and in a temperature range of −50 ° C. or higher and 300 ° C. or lower. A strain resistance film having a gauge ratio of 4 or more and having no grain boundary having a clear width containing oxygen.
−50℃以上200℃以下の温度範囲において、感度温度係数(TCS)が、±1500ppm/℃以内であることを特徴とする請求項1に記載の歪抵抗膜。 The strain resistance film according to claim 1, wherein the sensitivity temperature coefficient (TCS) is within ± 1500 ppm / ° C. in the temperature range of −50 ° C. or higher and 200 ° C. or lower. −50℃以上500℃以下の温度範囲において、抵抗温度係数(TCR)が、±500ppm/℃以内であることを特徴とする請求項1または請求項2に記載の歪抵抗膜。 The strain resistance film according to claim 1 or 2, wherein the temperature coefficient of resistance (TCR) is within ± 500 ppm / ° C. in the temperature range of −50 ° C. or higher and 500 ° C. or lower. 請求項1から請求項3のいずれか1項の歪抵抗膜を起歪構造体上に形成してなることを特徴とする歪センサ。 A strain sensor characterized in that the strain resistance film according to any one of claims 1 to 3 is formed on a strain generating structure. ガス圧が16mTorr以下で高周波スパッタリングすることにより、
一般式Cr100−x−yAl
(ただし、x、yは原子比率(at.%)であり、4≦x≦25、0.1≦y≦20である。)で表される薄膜を形成し、前記薄膜に、300℃以上700℃以下の温度で熱処理を施し、−50℃以上300℃以下の温度範囲において、ゲージ率が4以上の歪抵抗膜とすることを特徴とする歪抵抗膜の製造方法。
By high frequency sputtering at a gas pressure of 16 mTorr or less
General formula Cr 100-xy Al x N y
(However, x and y are atomic ratios (at.%), And 4 ≦ x ≦ 25 and 0.1 ≦ y ≦ 20.) A thin film is formed, and the temperature is 300 ° C. or higher. A method for producing a strain resistance film, which comprises performing heat treatment at a temperature of 700 ° C. or lower to form a strain resistance film having a gauge ratio of 4 or more in a temperature range of −50 ° C. or higher and 300 ° C. or lower.
前記熱処理によって膜表面に表面保護膜が形成されることを特徴とする請求項5に記載の歪抵抗膜の製造方法。 The method for producing a strain-resistant film according to claim 5 , wherein a surface protective film is formed on the film surface by the heat treatment. 前記表面保護膜は、Crおよび不可避的不純物からなることを特徴とする請求項に記載の歪抵抗膜の製造方法。 The method for producing a strain resistance film according to claim 6 , wherein the surface protective film is composed of Cr 2 O 3 and unavoidable impurities. −50℃以上200℃以下の温度範囲において、感度温度係数(TCS)が、±1500ppm/℃以内であることを特徴とする請求項5から請求項のいずれか1項に記載の歪抵抗膜の製造方法。 The strain resistance film according to any one of claims 5 to 7 , wherein the temperature coefficient of sensitivity (TCS) is within ± 1500 ppm / ° C. in the temperature range of −50 ° C. or higher and 200 ° C. or lower. Manufacturing method. −50℃以上500℃以下の温度範囲において、抵抗温度係数(TCR)が、±500ppm/℃以内であることを特徴とする請求項5から請求項のいずれか1項に記載の歪抵抗膜の製造方法。 The strain resistance film according to any one of claims 5 to 8 , wherein the temperature coefficient of resistance (TCR) is within ± 500 ppm / ° C. in the temperature range of −50 ° C. or higher and 500 ° C. or lower. Manufacturing method. ガス圧が16mTorr以下で高周波スパッタリングすることにより、
一般式Cr100−x−yAl
(ただし、x、yは原子比率(at.%)であり、4≦x≦25、0.1≦y≦20である。)で表される薄膜を起歪構造体上に形成し、300℃以上700℃以下の温度で熱処理を施し、請求項1から請求項3のいずれか1項の歪抵抗膜とすることにより歪センサを得ることを特徴とする歪センサの製造方法。
By high frequency sputtering at a gas pressure of 16 mTorr or less
General formula Cr 100-xy Al x N y
(However, x and y are atomic ratios (at.%), And 4 ≦ x ≦ 25 and 0.1 ≦ y ≦ 20). A method for manufacturing a strain sensor, which comprises subjecting a strain sensor to a strain resistance film according to any one of claims 1 to 3 by performing heat treatment at a temperature of ° C. or higher and 700 ° C. or lower to obtain a strain sensor.
前記熱処理によって膜表面に表面保護膜が形成されることを特徴とする請求項10に記載の歪センサの製造方法。 The method for manufacturing a strain sensor according to claim 10 , wherein a surface protective film is formed on the film surface by the heat treatment. 前記表面保護膜は、Crおよび不可避的不純物からなることを特徴とする請求項11に記載の歪センサの製造方法。 The method for manufacturing a strain sensor according to claim 11 , wherein the surface protective film is composed of Cr 2 O 3 and unavoidable impurities.
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