JP3631328B2

JP3631328B2 - Temperature detection element

Info

Publication number: JP3631328B2
Application number: JP19986296A
Authority: JP
Inventors: 雅彦三橋; 誠志郎大屋; 志郎唐澤; 小太郎篠原; 幸香盤若; 久男大澤; 由太郎荒井
Original assignee: Kanagawa Prefecture
Current assignee: Kanagawa Prefecture
Priority date: 1996-07-10
Filing date: 1996-07-10
Publication date: 2005-03-23
Anticipated expiration: 2016-07-10
Also published as: JPH1026559A

Description

【０００１】
【発明の属する技術分野】
本発明は温度検出の技術分野にかかり、特に、白金薄膜を使用した小型の温度検出素子に関する。
【０００２】
【従来の技術】
従来より、温度による抵抗値の変化を検出し、温度測定を行う測温素子には、白金薄膜を利用した温度検出素子が用いられている。図４の符号１０２に、従来技術の温度検出素子を示す。
【０００３】
この温度検出素子１０２は、アルミナや酸化マグネシウムから成る絶縁基板１０４上に白金薄膜が全面成膜され、次いで、エッチングによって、その白金薄膜がパターニングされ、白金測温抵抗体が形成されている。そのパターニングによって形成された白金測温抵抗体のうち、幅狭に形成され、絶縁基板１０４上を引き回された部分によって主抵抗部１１５が形成されている。
【０００４】
また、白金薄膜が幅広で四角形状にパターニングされた部分によって電極パッド１１９_１、１１９_２が形成されており、各電極パッド１１９_１、１１９_２は、主抵抗部１１５の両端に接続され、金属ワイヤーをワイヤーボンディングによって接続すると、外部電源から金属ワイヤーを介して主抵抗部１１５に電流を流せるように構成されている。
【０００５】
白金は正の抵抗温度係数を有しており、温度が上昇すると抵抗値が増大する。従って、このように構成された温度検出素子１０２では、主抵抗部１１５に一定の大きさの電流を流し、そのときに生じる電圧ドロップを測定することで、温度検出素子１０２の温度を知ることが可能となる。
【０００６】
電圧検出精度上、そのような電圧ドロップの測定には、小さくても１００Ω程度の抵抗値、望ましくは１０００Ω程度の抵抗値が必要であると言われているが、温度検出素子は小型であることが求められているため、白金測温抵抗体の抵抗値を大きくすることにも限界がある。
【０００７】
そこで従来より、主抵抗部と電極パッドとを２ｍｍ^２程度の面積にし、小型の温度検出素子を得るために、白金薄膜の膜厚をより一層薄くし、微細パターンを形成して抵抗値を増加させようとする努力が成されている。
【０００８】
しかしながら膜上に形成された白金では、その抵抗温度係数（ＴＣＲ）は成膜条件によって異なる他、膜厚によっても異なるという事実があり、バルク状態では３８５０ｐｐｍ／℃の値をとるのに対し、薄膜状態ではそれより小さな値になってしまうことが知られている。特に、１．０μｍ未満の膜厚にした場合、従来得られている白金薄膜では、３５００ｐｐｍ／℃〜３７８０ｐｐｍ／℃程度の低い抵抗温度係数のものしか得られていない。
【０００９】
ＴＣＲについては、ＪＩＳ規格で定められている３８５０ｐｐｍ／℃の値に近い白金測温抵抗体が求められており、そのような高いＴＣＲの値を得るためには、白金膜の膜厚を厚くせざるを得ず、そのため、微細パターンが形成できず、現状では１ｋΩで８ｍｍ^２、１００Ωでは２．４ｍｍ^２より小さいチップ部品としての温度検出素子は得られていない。
【００１０】
ところで、一般に、スパッタリング等によって成膜される白金膜は、微小な白金粒子の成長によって形成されることが知られており、その白金粒子の成長過程において、白金膜中に各種の転位や格子欠陥が生じたり、結晶粒界に構造欠陥が生じることが多い。そのような転移や欠陥は、白金膜の膜質を悪化させ、その結果、白金測温抵抗体のＴＣＲの値が低下すると考えられている。
【００１１】
このような白金膜に対しては、密着性を向上させようとする試みの中で、非晶質であるアルミナ基板等の表面を改質して密着還元層を設け、その密着還元層上に白金膜を形成することで、結果的に結晶性の良い白金薄膜を得ているものがある（特開平３−１３３１０１号公報）。
【００１２】
また、より直接的には、ジルコニア上に白金膜を形成した場合、メカニズムは明らかにされていないものの、そのＸ線回折解析結果の一例から、結晶性が良く、高い抵抗温度係数の白金膜が得られたとする報告（特開平２−５８３０４）がある。
【００１３】
しかしながら、単に非晶質絶縁基板表面を改質して密着還元層を設ける場合には、白金膜の密着性と結晶性は向上するものの、必ずしも抵抗温度係数が向上するとは限らない。
【００１４】
また、ジルコニア上に形成された従来の白金膜では、その表面をＸ線回折分析した場合、（１１１）面方位しか観察できない。（１１１）面方位のＸ線強度が強く、結晶性が良いと考えられる白金膜では、膜厚が小さくなり、薄膜化するに連れて抵抗温度係数が急速に低下してしまい、薄膜で高いＴＣＲの白金測温抵抗体を再現性良く得ることができなかった。
【００１５】
【発明が解決しようとする課題】
本発明は上記従来技術の不都合を解決するために創作されたもので、その目的は、小型で高い抵抗温度係数（ＴＣＲ）の温度検出素子が得られる技術を提供することにある。
【００１６】
【課題を解決するための手段】
上記課題を解決するために、請求項１記載の発明は、絶縁物上に形成された白金薄膜がパターニングされ、幅狭に成形された部分によって白金測温抵抗体が構成された温度検出素子であって、前記白金測温抵抗体表面のＸ線回折パターンは、（１００）面方位の強度が（１１１）面方位の強度に対し０．８１以上の値であることを特徴とする。
【００１７】
この場合、請求項２記載の発明のように、前記白金測温抵抗体は０．１８μｍ以上の膜厚にしておくことが望ましい。
【００１８】
そのような請求項１又は請求項２のいずれか１項記載の発明については、請求項３記載の発明のように、結晶系が立方晶系の絶縁物上に白金薄膜を形成して白金測温抵抗体を構成することが望ましい。
【００１９】
その立方晶系の絶縁物については、請求項４記載の発明のように、ＭｇＯを用いることができる。
【００２０】
また、前記絶縁物については、請求項５記載の発明のように、基板上に形成された薄膜で構成することも可能である。
【００２１】
以上の請求項１乃至請求項５のいずれか１項記載の温度検出素子については、請求項６記載の発明のように、前記白金測温抵抗体から成る主抵抗部と、前記白金測温抵抗体が電気的に並列接続されて成る第１の抵抗調節部とを設け、前記主抵抗部と前記第１の抵抗調節部とを直列接続させ、前記第１の抵抗調節部を構成する白金測温抵抗体の一部を切断すると、全体の抵抗値を調節できるように構成することが好ましい。
【００２２】
また、請求項１乃至請求項６のいずれか１項記載の温度検出素子については、請求項７記載の発明のように、前記白金薄膜の幅広に成形された部分から成る第２の抵抗調節部を設け、前記第２の抵抗調節部を前記主抵抗部と直列接続させ、前記第２の抵抗調節部の一部に切れ込みを入れて幅を調節すると、全体の抵抗値を調節できるように構成することが好ましい。
【００２３】
更に、請求項１乃至請求項７のいずれか１項記載の温度検出素子については、請求項８記載の発明のように、前記白金薄膜で構成された電極パッドであって、金属ワイヤーが接続されるべきものを設け、その電極パッドを介して前記白金測温抵抗体に通電できるように構成し、各電極パッドに対し、電気的に近接させて電圧測定用の電極パッドを接続することが望ましい。
【００２４】
上述した本発明の構成は、本発明の発明者等が、白金薄膜で構成した白金測温抵抗体の表面をＸ線回折法により分析し、その結果と抵抗温度係数（ＴＣＲ）の値との関連を検討したところ、（１１１）面方位の強度に対する（１００）面方位の強度比が大きい場合に、ＴＣＲの値が高いことを見出したことにより創作されたものである。
【００２５】
具体的に実験結果を説明すると、マグネトロンスパッタリング法によって絶縁物上に白金薄膜を成膜する際、スパッタリング中の絶縁物の温度を変え、同じ膜厚（０．１２μｍ）で、（１００）面方位と（１１１）面方位の強度が異なる白金測温抵抗体を作成し、ＴＣＲを測定した。その測定結果を下記表１に示す。
【００２６】
【表１】

【００２７】
この表１の通り、膜厚が同じ場合でも、（１００）面方位／（１１１）面方位の強度比が高い白金測温抵抗体の方がＴＣＲの値が高い。即ち、同じ膜厚であれば（１００）面方位／（１１１）面方位の値が高いほどＴＣＲの値を高くすることができると予想される。
【００２８】
但し、絶縁基板表面近傍の白金薄膜は結晶性が乱れ易いので、０．１μｍ程度の膜厚まで薄くなると、ＴＣＲの値は界面近傍の影響を強く受けてしまい、（１００）面方位／（１１１）面方位の強度比が高い場合でも、膜厚が厚い白金測温抵抗体に比べるとＴＣＲの値は低くなる傾向にある。
【００２９】
他方、白金測温抵抗体の膜厚が０．２μｍ程度まで厚くなると、界面近傍の影響は小さくなる。従って、例えば膜厚０．１８μｍの白金薄膜では、（１００）面方位／（１１１）面方位の強度比が０．８１のもので、３８４０ｐｐｍ／℃と高いＴＣＲの値が得られている。
【００３０】
ところで、白金の結晶系は立方晶系なので、白金薄膜を絶縁物上に成膜して構成する白金測温抵抗体では、その（１００）面方位の強度は、絶縁物の結晶系が白金と同じ立方晶系である場合に強くなると考えられる。下記表２に、白金薄膜の結晶系と絶縁物の結晶系の一例を示す。
【００３１】
【表２】

【００３２】
更に、格子のミスマッチを生じさせず、白金測温抵抗体の（１００）面方位の強度を強くするためには、格子定数の値が白金の格子定数に近いものを用いればよいと予想される。
【００３３】
【発明の実施の形態】
本発明の実施の形態を図面を用いて説明する。
図２の符号２は、本発明の一例の温度検出素子を示しており、表面が（１００）面方位のＭｇＯ結晶基板で構成された絶縁物４を有しており、その表面に白金薄膜で構成された白金測温抵抗体５が形成されている。
【００３４】
その白金測温抵抗体５の形成方法を説明すると、まず、絶縁物４をスパッタリング装置内に搬入し、高真空状態に置いた後、１．０×１０^−２Ｔｏｒｒの圧力までアルゴンガスを導入し、２００Ｗの投入電力で白金ターゲットを高周波マグネトロンスパッタリングし、絶縁物４表面に膜厚０．１８μｍの白金薄膜を全面成膜した。
【００３５】
次いで、その絶縁基板４をスパッタリング装置内から取り出し、フォトリソグラフィとプラズマエッチングによってパターニングし、白金薄膜が幅狭に成形された部分によって、断面図の図１（ａ）に示すような白金測温抵抗体５を構成した。
【００３６】
そのパターニングの際、絶縁物４上で白金測温抵抗体５を折れ曲げ、一定面積内でできるだけ抵抗値が大きくなるように引き回して主抵抗部１５_１、１５_２を構成し、また、白金測温抵抗体５を電気的に並列接続して第１の抵抗調節部１７_１、１７_２を構成し、更に、白金薄膜が幅広に成形された部分によって、第２の抵抗調節部１６を構成した。
【００３７】
また、白金薄膜のパターニングの際、主抵抗部１５_１、１５_２と、第１の抵抗調節部１７_１、１７_２と、第２の抵抗調節部１６とはこの順で直列接続されるようにした。そして、その直列接続された抵抗回路の両端に電極パッド１９_１、１９_２が接続されるようにし、各電極パッド１９_１、１９_２に金属ワイヤーをワイヤーボンディングして外部電源に接続できるように構成した。
【００３８】
この電極パッド１９_１、１９_２と白金測温抵抗体５とが接続されたところに、電気的に近接して電極パッド１８_１、１８_２がそれぞれ接続されるようにし、電極パッド１９_１、１９_２の間に電圧を印加し、主抵抗部１５_１、１５_２と第１、第２の抵抗調節部１７_１、１７_２、１６に電流を流したときに生じる電圧ドロップを、電極パッド１８_１、１８_２の間の電位を測定することで検出できるように構成した。
【００３９】
このような構成によれば、第１、第２の抵抗調節部１７_１、１７_２、１６にスポット状のレーザー光を照射し、第１の抵抗調節部１７_１、１７_２の並列接続された白金測温抵抗体５の所望のものを切断したり、第２の抵抗調節部１６に切れ込みを入れたりすれば全体の抵抗値を調節できるので、所望抵抗値の温度検出素子２を得ることが可能となる。
【００４０】
この温度検出素子２に形成した白金測温抵抗体５の特性を測定したところ、厚みは、０．１８μｍ、抵抗温度係数（ＴＣＲ）は、ＪＩＳ規格で定められている３８５０ｐｐｍ／℃に近い値の３８４０ｐｐｍ／℃（平均値）が得られた。
【００４１】
この実施例と同じ成膜条件で、高い（１００）面方位強度で膜厚が異なる白金薄膜をＭｇＯ上に成膜し、パターニングによって白金測温抵抗体を構成し、ＴＣＲの値を測定した。その結果を下記表３に示す。
【００４２】
【表３】

【００４３】
いずれの膜厚のものでも、（１００）面方位／（１１１）面方位の強度比が高く、高い値のＴＣＲが得られている。
【００４４】
比較例として、絶縁物にサファイア基板とアルミナ基板とを用い、上述のマグネトロンスパッタリングの条件と同じ条件で白金薄膜を成膜し、パターニングによって白金測温抵抗体を形成してＴＣＲの値を測定した。その結果を下記表４、表５に示す。
【００４５】
【表４】

【００４６】
【表５】

【００４７】
サファイア基板、アルミナ基板とも、その表面に形成された白金測温抵抗体の（１００）面方位／（１１１）面方位の強度比は小さく、ＴＣＲの値は低い。
【００４８】
これらの結果を図３のグラフにまとめて示す。ＭｇＯ上に白金測温抵抗体５を形成した場合には小さい膜厚まで高いＴＣＲの値を維持できることが分かる。
【００４９】
以上説明した実施例は、基板状のＭｇＯから成る絶縁物４表面に白金薄膜を成膜し、白金測温抵抗体５を形成した場合であるが、図１（ｂ）に示すように、シリコン基板７表面に、エキシマレーザ蒸着法によって、温度３００〜６００℃、成長速度０．３Å／秒〜０．５Å／秒にてＭｇＯから成る薄膜を形成して絶縁物６とし、その絶縁物６表面に白金薄膜を成膜し、パターニングにして白金測温抵抗体５’を形成したところ、表１と同様に（１００）面方位／（１１１）面方位の強度比が高く、高いＴＣＲの値が得られた。
【００５０】
なお、薄膜で構成した絶縁物６’については、図１（ｃ）に示すように、白金測温抵抗体５’と同じ形状にパターニングすることができる。
【００５１】
【発明の効果】
本発明によれば、膜厚が薄くても高い抵抗温度係数（ＴＣＲ）の白金測温抵抗体を得ることができる。
【００５２】
白金薄膜によって白金測温抵抗体を構成したので、微細なパターニングによって小型で抵抗値が大きい温度検出素子を得ることができる。小型であれば、一つの基板から多数の温度検出素子を得ることができるので、低コストになるばかりでなく、小型であるために熱容量が小さくなり、応答速度を向上させることができる。
【００５３】
特に、基板上に絶縁物の薄膜を形成し、その表面に白金膜を成膜して温度検出素子を構成する場合には、測定物の熱容量や比熱を考慮して基板を選択すると、温度検出素子の特性を比測定物の特性に対応させることができるので、正確な測定を行うことが可能となる。
【図面の簡単な説明】
【図１】（ａ）：本発明の温度検出素子の一例の断面図
（ｂ）：他の例の断面図
（ｃ）：更に他の例の断面図
【図２】本発明の温度検出素子の一例の平面図
【図３】ＭｇＯ、サファイア、アルミナ上に形成した白金測温抵抗体のＴＣＲの値を示すグラフ
【図４】従来技術の温度検出素子を説明するための平面図
【符号の説明】
２、２’、２”……温度検出素子４、６、６’……絶縁物
５、５’……白金測温抵抗体７、７’……基板
１５_１、１５_２……主抵抗部１６……第２の抵抗調節部
１７_１、１７_２……第１の抵抗調節部
１８_１、１８_２、１９_１、１９_２……電極パッド[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the technical field of temperature detection, and particularly relates to a small temperature detection element using a platinum thin film.
[0002]
[Prior art]
Conventionally, a temperature detecting element using a platinum thin film is used as a temperature measuring element that detects a change in resistance value due to temperature and measures temperature. Reference numeral 102 in FIG. 4 shows a temperature detection element of the prior art.
[0003]
In this temperature detecting element 102, a platinum thin film is entirely formed on an insulating substrate 104 made of alumina or magnesium oxide, and then the platinum thin film is patterned by etching to form a platinum resistance temperature detector. Of the platinum resistance thermometer formed by the patterning, the main resistance portion 115 is formed by a portion that is formed narrow and is routed on the insulating substrate 104.
[0004]
In addition, electrode pads 119 ₁ and 119 ₂ are formed by a wide and square-patterned portion of the platinum thin film, and the electrode pads 119 ₁ and 119 ₂ are connected to both ends of the main resistor 115 and are connected to metal wires. Are connected by wire bonding, an electric current can be passed from the external power source to the main resistor 115 via the metal wire.
[0005]
Platinum has a positive resistance temperature coefficient, and the resistance value increases as the temperature rises. Therefore, in the temperature detection element 102 configured as described above, the temperature of the temperature detection element 102 can be known by flowing a constant current through the main resistor 115 and measuring a voltage drop generated at that time. It becomes possible.
[0006]
In terms of voltage detection accuracy, it is said that such a voltage drop measurement requires a resistance value of at least about 100Ω, preferably about 1000Ω, but the temperature detection element is small. Therefore, there is a limit to increasing the resistance value of the platinum resistance thermometer.
[0007]
Therefore, in order to obtain a small temperature detection element by making the main resistance part and the electrode pad about 2 mm ^{2 in the} past, the thickness of the platinum thin film is further reduced, and the resistance value is increased by forming a fine pattern. Efforts to make it happen.
[0008]
However, platinum formed on the film has the fact that its temperature coefficient of resistance (TCR) varies depending on the film forming conditions and also on the film thickness. In the bulk state, the value is 3850 ppm / ° C. It is known that the value will be smaller in that state. In particular, when the film thickness is less than 1.0 μm, conventionally obtained platinum thin films have only a low resistance temperature coefficient of about 3500 ppm / ° C. to 3780 ppm / ° C.
[0009]
For TCR, a platinum resistance thermometer that is close to the value of 3850 ppm / ° C. stipulated in the JIS standard is required, and in order to obtain such a high TCR value, the thickness of the platinum film must be increased. forced to not give, therefore, it can not be fine pattern formation, ^{8 mm} 2, the temperature sensing element as 2.4 mm ² smaller than the chip component at 100Ω has not been obtained in 1kΩ at present.
[0010]
By the way, it is generally known that a platinum film formed by sputtering or the like is formed by the growth of minute platinum particles. During the growth process of the platinum particles, various dislocations and lattice defects are formed in the platinum film. And structural defects often occur at the grain boundaries. Such dislocations and defects are thought to deteriorate the quality of the platinum film, resulting in a decrease in the TCR value of the platinum resistance thermometer.
[0011]
For such a platinum film, in an attempt to improve adhesion, the surface of an amorphous alumina substrate or the like is modified to provide an adhesion reduction layer, and the adhesion reduction layer is formed on the adhesion reduction layer. As a result, there is a film obtained by forming a platinum thin film with good crystallinity by forming a platinum film (JP-A-3-133101).
[0012]
More directly, when a platinum film is formed on zirconia, the mechanism has not been clarified, but from an example of the X-ray diffraction analysis result, a platinum film with good crystallinity and a high resistance temperature coefficient is obtained. There is a report (JP-A-2-58304) that it was obtained.
[0013]
However, when the surface of the amorphous insulating substrate is simply modified to provide the adhesion reduction layer, although the adhesion and crystallinity of the platinum film are improved, the temperature coefficient of resistance is not necessarily improved.
[0014]
Further, in the conventional platinum film formed on zirconia, when the surface is subjected to X-ray diffraction analysis, only the (111) plane orientation can be observed. A platinum film that has a strong (111) plane X-ray intensity and good crystallinity has a small film thickness, and the temperature coefficient of resistance rapidly decreases as the film is thinned. The platinum resistance temperature detector could not be obtained with good reproducibility.
[0015]
[Problems to be solved by the invention]
The present invention was created to solve the above-described disadvantages of the prior art, and an object of the present invention is to provide a technique capable of obtaining a small-sized and high resistance temperature coefficient (TCR) temperature detecting element.
[0016]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a temperature detecting element in which a platinum thin film formed on an insulator is patterned and a platinum resistance thermometer is constituted by a narrowly formed portion. In the X-ray diffraction pattern on the surface of the platinum resistance thermometer, the intensity of (100) plane orientation is 0.81 or more with respect to the intensity of (111) plane orientation.
[0017]
In this case, it is desirable that the platinum resistance thermometer has a film thickness of 0.18 μm or more as in the invention described in claim 2.
[0018]
With regard to the invention according to any one of

claims

1 and 2, as in the invention according to claim 3, a platinum thin film is formed on an insulator whose crystal system is a cubic system and platinum measurement is performed. It is desirable to construct a temperature resistor.
[0019]
As for the cubic insulator, MgO can be used as in the fourth aspect of the invention.
[0020]
In addition, the insulator can be constituted by a thin film formed on a substrate as in the invention described in claim 5.
[0021]
The temperature detecting element according to any one of claims 1 to 5, as in the invention according to claim 6, includes a main resistance portion made of the platinum resistance thermometer and the platinum resistance thermometer. A first resistance adjusting unit having a body electrically connected in parallel, and connecting the main resistance unit and the first resistance adjusting unit in series to form a platinum measuring device constituting the first resistance adjusting unit. It is preferable that the entire resistance value be adjusted by cutting a part of the temperature resistor.
[0022]
The temperature detection element according to any one of claims 1 to 6, as in the invention according to claim 7, is a second resistance adjusting portion comprising a wide-shaped portion of the platinum thin film. And the second resistance adjusting unit is connected in series with the main resistance unit, and the overall resistance value can be adjusted by adjusting the width by cutting a part of the second resistance adjusting unit. It is preferable to do.
[0023]
Further, the temperature detection element according to any one of claims 1 to 7 is an electrode pad configured by the platinum thin film as in the invention according to claim 8, and a metal wire is connected thereto. It is desirable that the platinum resistance thermometer element is energized through the electrode pads, and the electrode pads for voltage measurement are connected to each electrode pad in electrical proximity. .
[0024]
In the configuration of the present invention described above, the inventors of the present invention analyze the surface of a platinum resistance temperature detector composed of a platinum thin film by an X-ray diffraction method, and the result and the value of the resistance temperature coefficient (TCR) As a result of examining the relationship, it was created by finding that the TCR value is high when the intensity ratio of the (100) plane orientation to the intensity of the (111) plane orientation is large.
[0025]
Specifically, the experimental results will be described. When a platinum thin film is formed on an insulator by a magnetron sputtering method, the temperature of the insulator during sputtering is changed, and the (100) plane orientation with the same film thickness (0.12 μm). Platinum resistance thermometers having different intensities in the (111) plane orientation were prepared, and TCR was measured. The measurement results are shown in Table 1 below.
[0026]
[Table 1]

[0027]
As shown in Table 1, even when the film thickness is the same, the platinum resistance thermometer having a higher intensity ratio of (100) plane orientation / (111) plane orientation has a higher TCR value. That is, it is expected that the TCR value can be increased as the value of the (100) plane orientation / (111) plane orientation is higher for the same film thickness.
[0028]
However, since the platinum thin film near the surface of the insulating substrate is easily disturbed in crystallinity, when the film thickness is reduced to about 0.1 μm, the TCR value is strongly influenced by the vicinity of the interface, and the (100) plane orientation / (111 ) Even when the intensity ratio of the plane orientation is high, the TCR value tends to be lower than that of a platinum resistance thermometer having a large film thickness.
[0029]
On the other hand, when the thickness of the platinum resistance thermometer increases to about 0.2 μm, the influence in the vicinity of the interface is reduced. Therefore, for example, a platinum thin film having a film thickness of 0.18 μm has an intensity ratio of (100) plane orientation / (111) plane orientation of 0.81, and a high TCR value of 3840 ppm / ° C. is obtained.
[0030]
By the way, since the crystal system of platinum is a cubic system, in the platinum resistance thermometer configured by forming a platinum thin film on an insulator, the strength of the (100) plane orientation is the same as that of the insulator crystal system. It is thought that it becomes strong when they are the same cubic system. Table 2 below shows an example of the crystal system of the platinum thin film and the crystal system of the insulator.
[0031]
[Table 2]

[0032]
Furthermore, in order to increase the strength of the (100) plane orientation of the platinum resistance thermometer without causing lattice mismatch, it is expected that a lattice constant value close to that of platinum should be used. .
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
Reference numeral 2 in FIG. 2 shows a temperature detecting element of an example of the present invention, which has an insulator 4 whose surface is composed of an MgO crystal substrate having a (100) plane orientation, and a platinum thin film on the surface. The platinum resistance temperature detector 5 comprised is formed.
[0034]
The formation method of the platinum resistance temperature detector 5 will be described. First, the insulator 4 is carried into a sputtering apparatus and placed in a high vacuum state, and then argon gas is introduced to a pressure of 1.0 × 10 ⁻² Torr. Then, a platinum target was subjected to high-frequency magnetron sputtering with an input power of 200 W, and a platinum thin film having a thickness of 0.18 μm was formed on the entire surface of the insulator 4.
[0035]
Next, the insulating substrate 4 is taken out from the sputtering apparatus, patterned by photolithography and plasma etching, and a platinum resistance thermometer as shown in FIG. Body 5 was constructed.
[0036]
At the time of patterning, the platinum resistance thermometer 5 is bent on the insulator 4 and drawn so that the resistance value becomes as large as possible within a certain area to form the main resistance portions 15 ₁ and 15 _2. The first resistance adjusting portions 17 ₁ and 17 ₂ are configured by electrically connecting the temperature resistors 5 in parallel, and the second resistance adjusting portion 16 is configured by a portion in which the platinum thin film is formed wide. .
[0037]
Further, when patterning the platinum thin film, the main resistance portions 15 ₁ and 15 ₂ , the first resistance adjustment portions 17 ₁ and 17 ₂ , and the second resistance adjustment portion 16 are connected in series in this order. did. The electrode pads 19 ₁ and 19 ₂ are connected to both ends of the resistance circuit connected in series, and a metal wire is wire-bonded to the electrode pads 19 ₁ and 19 ₂ so as to be connected to an external power source. did.
[0038]
The electrode pads 19 ₁ , 19 ₂ and the platinum resistance thermometer 5 are connected to each other so that the electrode pads 18 ₁ , 18 ₂ are connected in electrical proximity to each other, so that the electrode pads 19 ₁ , 19 ₂ are connected. a voltage is applied between the _two, the main resistor portion ₁₅ 1, 15 ₂ and the first, a voltage drop occurring when current flows in the second

resistance controlling portion

₁₇ 1, ₁₇ 2, 16, the electrode pads 18 ₁ It was constructed as can be detected by measuring the potential between 18 _2.
[0039]
According to such a configuration, the first and second resistance adjusting units 17 ₁ , 17 ₂ , and 16 are irradiated with spot-shaped laser light, and the first resistance adjusting units 17 ₁ and 17 ₂ are connected in parallel. Since the entire resistance value can be adjusted by cutting a desired one of the platinum resistance thermometer 5 or making a notch in the second resistance adjusting section 16, it is possible to obtain the temperature detecting element 2 having a desired resistance value. It becomes possible.
[0040]
When the characteristics of the platinum resistance thermometer 5 formed on the temperature detecting element 2 were measured, the thickness was 0.18 μm, and the resistance temperature coefficient (TCR) was a value close to 3850 ppm / ° C. defined by the JIS standard. 3840 ppm / ° C. (average value) was obtained.
[0041]
Under the same film forming conditions as in this example, platinum thin films having different (100) plane orientation strengths and different film thicknesses were formed on MgO, a platinum resistance thermometer was formed by patterning, and the TCR value was measured. The results are shown in Table 3 below.
[0042]
[Table 3]

[0043]
In any film thickness, the intensity ratio of (100) plane orientation / (111) plane orientation is high, and a high value of TCR is obtained.
[0044]
As a comparative example, a sapphire substrate and an alumina substrate were used as insulators, a platinum thin film was formed under the same conditions as the above-described magnetron sputtering, a platinum resistance temperature detector was formed by patterning, and a TCR value was measured. . The results are shown in Tables 4 and 5 below.
[0045]
[Table 4]

[0046]
[Table 5]

[0047]
In both the sapphire substrate and the alumina substrate, the platinum resistance thermometer formed on the surface has a small (100) plane / (111) plane intensity ratio and a low TCR value.
[0048]
These results are summarized in the graph of FIG. It can be seen that when the platinum resistance thermometer 5 is formed on MgO, a high TCR value can be maintained up to a small film thickness.
[0049]
The embodiment described above is a case where a platinum thin film is formed on the surface of the substrate-like insulator 4 made of MgO, and the platinum resistance thermometer 5 is formed. As shown in FIG. A thin film made of MgO is formed on the surface of the substrate 7 by an excimer laser deposition method at a temperature of 300 to 600 ° C. and a growth rate of 0.3 to 0.5 to 0.5 tons / second. A platinum thin film RTD 5 ′ was formed by patterning and forming a platinum resistance temperature detector 5 ′. As in Table 1, the intensity ratio of (100) plane orientation / (111) plane orientation was high, and a high TCR value was obtained. Obtained.
[0050]
In addition, about the insulator 6 'comprised by the thin film, as shown in FIG.1 (c), it can pattern to the same shape as platinum resistance temperature detector 5'.
[0051]
【The invention's effect】
According to the present invention, a platinum resistance temperature detector having a high temperature coefficient of resistance (TCR) can be obtained even if the film thickness is small.
[0052]
Since the platinum resistance temperature detector is constituted by the platinum thin film, a small temperature detection element having a large resistance value can be obtained by fine patterning. If the size is small, a large number of temperature detection elements can be obtained from one substrate, so that not only the cost is reduced, but also the heat capacity is reduced because of the small size, and the response speed can be improved.
[0053]
In particular, when a thin film of an insulator is formed on a substrate and a platinum film is formed on the surface to form a temperature detection element, the temperature can be detected by selecting the substrate in consideration of the heat capacity and specific heat of the measurement object. Since the characteristics of the element can correspond to the characteristics of the specific measurement object, it is possible to perform accurate measurement.
[Brief description of the drawings]
1A is a cross-sectional view of an example of a temperature detection element of the present invention, FIG. 1B is a cross-sectional view of another example, and FIG. 2C is a cross-sectional view of still another example. FIG. FIG. 3 is a graph showing the TCR value of a platinum resistance thermometer formed on MgO, sapphire, and alumina. FIG. 4 is a plan view for explaining a conventional temperature detecting element. Description】
2, 2 ', 2 "...

Temperature detection element

4, 6, 6' ... Insulator 5, 5 '... Platinum resistance temperature detector 7,7' ... Substrate 15 ₁ , 15 ₂ ... Main resistance part 16... Second resistance adjuster 17 ₁ , 17 ₂ ... First resistance adjuster 18 ₁ , 18 ₂ , 19 ₁ , 19 _2.

Claims

A platinum thin film formed on an insulator is patterned, and a temperature sensing element in which a platinum resistance thermometer is configured by a narrowly shaped portion,
The X-ray diffraction pattern on the surface of the platinum resistance temperature detector has a (100) plane orientation strength of 0.81 or more with respect to the (111) plane orientation strength.

2. The temperature detecting element according to claim 1, wherein the platinum resistance thermometer has a thickness of 0.18 [mu] m or more.

The temperature detection element according to claim 1, wherein a crystal system of the insulator is a cubic system.

4. The temperature detecting element according to claim 3, wherein the insulator is MgO.

The temperature detecting element according to claim 1, wherein the insulator is formed of a thin film formed on a substrate.

A main resistance portion comprising the platinum resistance thermometer;
A platinum resistance thermometer having a first resistance adjusting unit electrically connected in parallel;
The main resistance unit and the first resistance adjustment unit are connected in series,
6. The structure according to claim 1, wherein the entire resistance value can be adjusted by cutting a part of the platinum resistance thermometer constituting the first resistance adjusting unit. The temperature detecting element according to the item.

A second resistance adjusting portion comprising a wide portion of the platinum thin film is provided;
The second resistance adjustment unit is connected in series with the main resistance unit,
7. The structure according to claim 1, wherein when the width is adjusted by cutting a part of the second resistance adjusting portion, the entire resistance value can be adjusted. Temperature sensing element.

It is composed of the platinum thin film, provided with an electrode pad to which a metal wire is to be connected,
A temperature detecting element configured to be able to energize the platinum resistance thermometer through the electrode pad,
8. The temperature detecting element according to claim 1, wherein an electrode pad for voltage measurement is connected in close proximity to an electrode pad for energizing the platinum resistance thermometer. .