JP3608427B2 - Infrared absorber and thermal infrared sensor using the infrared absorber - Google Patents

Infrared absorber and thermal infrared sensor using the infrared absorber Download PDF

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JP3608427B2
JP3608427B2 JP10430499A JP10430499A JP3608427B2 JP 3608427 B2 JP3608427 B2 JP 3608427B2 JP 10430499 A JP10430499 A JP 10430499A JP 10430499 A JP10430499 A JP 10430499A JP 3608427 B2 JP3608427 B2 JP 3608427B2
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infrared
metal thin
thin film
absorber
thin films
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JP2000292254A (en
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顕治 櫻井
文彦 佐藤
正和 椎木
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Omron Corp
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Omron Corp
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【０００１】
【発明の属する技術分野】
本発明は、赤外線吸収体及びこの赤外線吸収体を用いた熱型赤外線センサに関するものである。
【０００２】
【従来の技術】
赤外線吸収体は熱型赤外線センサに多く用いられており、外部からの入射赤外線エネルギーを赤外線吸収体により熱に変換し、その熱を熱型赤外線センサにより電気信号に変換している。
【０００３】
従来、この入射赤外線を熱に変換するための赤外線吸収体には、▲１▼金属を電気が流れない程度の厚さで蒸着する方法で形成されたものや、▲２▼金黒、▲３▼カーボンペースト塗布膜、▲４▼白金などをメッキにより被膜する方法で形成されたものがある。
【０００４】
▲１▼は、金属薄膜の膜厚を電気が流れない程度の膜厚にすると、金属薄膜に赤外線を入射した時、金属薄膜中の電子が振動し、そのエネルギーが熱に変換される。この金属薄膜の赤外線吸収率は、赤外線反射率および透過率が等しくなる膜厚で最大となり、最大値は理論的にはＯ．５（５０％）と低い。しかし、通常の蒸着装置があれば簡単に製造でき、熱容量が小さいため応答速度が速いという利点がある（文献名：Ｚｅｉｔｓｃｈｒｉｆｔ ｆｕｒ Ｐｈｙｓｉｋ，巻号：ｖｏｌ９１，ｐｐ２３０〜２５１、出版年：１９３４参照）。
【０００５】
図１０及び図１１に示すように、▲１▼金属を電気が流れない程度の厚さで蒸着する方法で形成された赤外線吸収体９は、熱型赤外線センサ（サーモパイルセンサ）のセンサチップＧの受光部分を形成している。このセンサチップＧは、シリコン製の半導体基板１０上にメンブレン１１を結合して構成してある。そして、図１２に示すように、メンブレン１１は一方の誘電薄膜１２上に形成した複数個（１１個）の熱電対（サーモパイル）１３を直列に接続し、且つこれらの複数個の熱電対１３を十字状に配置して各熱電対１３の温接点部（測温接点）１４を中心側に配し各熱電対１３の冷接点部（基準接点）１５を外側に配し、且つ２つの端子部１６、１７を形成し、これらの熱電対１３を他方の誘電薄膜１８で被覆して構成してある。
【０００６】
そして、熱電対１３は異種金属、例えばＢｉ製の線材１９とＳｂ製の線材２０とから構成してあり、温接点部１４及び冷接点部１５は両線材１９、２０を重ね合わせて構成してある。
【０００７】
そして、受光部分である赤外線吸収体９の形成はメンブレン１１上に金属薄膜を蒸着することにより行われる。
【０００８】
【発明が解決しようとじている課題】
吸収効率の良い材料としては、▲２▼金黒、▲３▼カーボンペースト塗布膜、▲４▼メッキによる白金被膜などがあるが、▲２▼金黒を形成するためには低真空蒸着機が必要であり、形成した赤外線吸収体は強度が弱いという問題点があった。
【０００９】
また、▲３▼カーボンペースト塗布膜は赤外線センサ上のパタ−ニングが容易であるが、赤外線センサを形成する基材（Ｓｉ）を異方性エッチングするための薬液に対する耐薬品性がないために生産が困難になるという問題点があった。
【００１０】
また、▲４▼メッキによる白金被膜も同様に専用の装置が必要となり、その材料が高価であるという問題点があった。
【００１１】
また、これらの材料は熱容量が大きいため、金属薄膜に比べて応答速度が遅くなるという問題点もあった。（金属薄膜を赤外線吸収体に用いた場合、時定数は、金黒、樹脂材料を用いたものの約半分である）。
【００１２】
また、▲１▼金属を電気が流れない程度の厚さで蒸着する方法で形成された赤外線吸収体９にあっては、その金属薄膜の生産が容易であって、低コストで形成できるが、赤外線吸収率は０．５（５０％）と低い。赤外線吸収率の高い他の赤外線吸収体を形成するには専用の装置が必要であったり、材料のコストが高いなどの問題点があった。
【００１３】
本発明は上記の問題点に着目して成されたものであって、その第１の目的とするところは、赤外線吸収率が高く、且つ高速応答性を持ち、低コストで生産が容易な赤外線吸収体を提供することにある。
【００１４】
また、本発明の第２の目的とするところは、赤外線吸収率が高く、且つ高速応答性を持ち、低コストで生産が容易な赤外線吸収体を用いた熱型赤外線センサを提供することにある。
【００１５】
【課題を解決するための手段】
上記の第１の目的を達成するために、請求項１の発明に係る赤外線吸収体は、外部からの入射赤外線のエネルギーを熱に変換するための赤外線吸収体であって、少なくとも２つ以上の金属薄膜を有し、且つその隣り合う前記金属薄膜間に絶縁膜を介在させて多層構造にした赤外線吸収体であって、前記多層構造における金属薄膜は、共に、単層における赤外線吸収率を最大０．５（５０％）でしかも互いに絶縁できる程度の薄膜で構成し、且つ、最終段の金属薄膜における赤外線透過率よりも赤外線反射率を大きくすると共に、前記最終段の金属薄膜以外の前記金属薄膜における赤外線反射率よりも赤外線透過率を大きくして構成したことを特徴とするものである。
【００１６】
かかる構成により、隣り合う金属薄膜間を絶縁すると共に、隣り合う金属薄膜を熱的に接続することが可能になり、隣り合う金属薄膜のうち、一方の金属薄膜を透過した赤外線は、他方の金属薄膜で吸収でき、他方の金属薄膜で反射した赤外線を一方の金属薄膜で吸収できるために、単層時の金属薄膜に比べより多くの赤外線を吸収することができる。このように赤外線吸収率が高く、且つ高速応答性を持ち、低コストで生産が容易な赤外線吸収体を提供することができる。
【００１８】
また、かかる構成により、隣り合う金属薄膜間を絶縁すると共に、隣り合う金属薄膜を熱的に接続することが可能になり、隣り合う金属薄膜のうち、一方の金属薄膜を透過した赤外線は、他方の金属薄膜で吸収でき、他方の金属薄膜で反射した赤外線を一方の金属薄膜で吸収できるために、単層時の金属薄膜に比べより多くの赤外線を吸収することができる。
【００１９】
しかも、多層構造における最終段の金属薄膜は、その赤外線透過率よりも赤外線反射率を大きくし、最終段の前記金属薄膜以外の金属薄膜は、その赤外線反射率よりも赤外線透過率を大きくしてあるために、より多くの赤外線が最終段の金属薄膜に到達し、この最終段の金属薄膜はより多くの赤外線を反射し、反射光は再び最終段の金属薄膜以外の金属薄膜で吸収されて、赤外線吸収率が向上する。例えば、２層構造の赤外線吸収体であれば、赤外線吸収率は０．５（単層時）から０．７に向上するし、３層構造の赤外線吸収体であれば、赤外線吸収率は０．５（単層時）から０．８に向上する。
【００２０】
また、上記の第１の目的を達成するために、請求項２の発明に係る赤外線吸収体は、外部からの入射赤外線のエネルギーを熱に変換するための赤外線吸収体であって、一方の金属薄膜と他方の金属薄膜との間に絶縁膜を介在させ、且つ赤外線の入射方向に、前記一方の金属薄膜と前記他方の金属薄膜とをこの順序で配置し、前記他方の金属薄膜の面積を前記一方の金属薄膜の面積より大きくして、前記他方の金属薄膜に赤外線の直接入射箇所を設けたものである。
【００２１】
かかる構成により、請求項１の発明の作用効果と同様な作用効果を奏し得るばかりか、他方の金属薄膜の面積は一方の金属薄膜の面積より大きくしてあり、一方の金属薄膜が他方の金属薄膜を覆っていない赤外線の直接入射箇所では、入射赤外線を直接に他方の金属薄膜で吸収し、また、他方の金属薄膜による入射赤外線の反射光のうち垂直でない方向の反射光をより多く一方の金属薄膜に入射することができる。このために、単層時の金属薄膜に比べより多くの赤外線を吸収できる。
【００２２】
また、上記の第２の目的を達成するために、請求項３の発明に係る熱型赤外線センサは、赤外線吸収体を、少なくとも２つ以上の金属薄膜を有し且つその隣り合う前記金属薄膜間に絶縁膜を介在させて多層構造に構成し、また、前記多層構造における金属薄膜は、共に、単層における赤外線吸収率を最大０．５（５０％）でしかも互いに絶縁できる程度の薄膜で構成し、且つ、最終段の金属薄膜における赤外線透過率よりも赤外線反射率を大きくすると共に、前記最終段の金属薄膜以外の前記金属薄膜における赤外線反射率よりも赤外線透過率を大きくして構成した受光部にしたものである。
【００２３】
かかる構成により、赤外線吸収体の一方の金属薄膜を透過した赤外線を、他方の金属薄膜で吸収でき、他方の金属薄膜で反射した赤外線を一方の金属薄膜で吸収できるため、単層時の金属薄膜に比べより多くの赤外線を吸収できる。このように吸収率の増加に比例してセンサ出力が向上するために、感度が向上し、周囲の温度のふらつきによる雑音も軽減できるためにセンサの精度が向上する。このように、赤外線吸収率が高く、且つ高速応答性を持ち、低コストで生産が容易な赤外線吸収体を用いた熱型赤外線センサを提供することができる。
【００２４】
しかも、多層構造における最終段の金属薄膜は、その赤外線透過率よりも赤外線反射率を大きくし、最終段の前記金属薄膜以外の金属薄膜は、その赤外線反射率よりも赤外線透過率を大きくしてあるために、より多くの赤外線が最終段の金属薄膜に到達し、この最終段の金属薄膜はより多くの赤外線を反射し、反射光は再び最終段の金属薄膜以外の金属薄膜で吸収されて、赤外線吸収率が向上する。例えば、２層構造の赤外線吸収体であれば、赤外線吸収率は０．５（単層時）から０．７に向上するし、３層構造の赤外線吸収体であれば、赤外線吸収率は０．５（単層時）から０．８に向上する。
【００２７】
また、上記の第２の目的を達成するために、請求項４の発明に係る熱型赤外線センサは、請求項３に記載の熱型赤外線センサにおいて、絶縁膜は、熱電対を誘電薄膜に封入したメンブレンである。
【００２８】
かかる構成により、請求項３の発明の作用効果と同様な作用効果を奏し得るばかりか、一方の金属薄膜をメンブレンの一方の面に形成し、他方の金属薄膜をメンブレンの他方の面に形成することにより絶縁膜を無くすことができて、熱型赤外線センサの受光部の構成を簡略化することができる。
【００２９】
また、上記の第２の目的を達成するために、請求項５の発明に係る熱型赤外線センサは、赤外線吸収体を、少なくとも２つ以上の金属薄膜を有し、且つその隣り合う前記金属薄膜間に絶縁膜を介在させて多層構造にし、前記多層構造における金属薄膜が、共に、単層における赤外線吸収率を最大０．５（５０％）でしかも互いに絶縁できる程度の薄膜で構成し、且つ、最終段の金属薄膜における赤外線透過率よりも赤外線反射率を大きくすると共に、前記最終段の金属薄膜以外の前記金属薄膜における赤外線反射率よりも赤外線透過率を大きくして構成した部分赤外線吸収部で構成し、当該部分赤外線吸収部を感温部上のみに形成した受光部にしたものである。
【００３０】
かかる構成により、請求項３の発明の作用効果と同様な作用効果を奏し得るばかりか、サーモパイルセンサのように受光部が感温部、すなわち温接点部上にのみでよい場合、温接点部上に部分赤外線吸収部を形成することで、受光部全体の熱容量を小さくでき、その結果、応答速度が早くなる。
【００３１】
【発明の実施の形態】
以下、本発明の実施例を図面を参照して詳細に説明する。
【００３２】
（実施の形態例１）
本発明に係る赤外線吸収体の実施の形態例１を図１乃至図３に示す。
図１は本発明に係る赤外線吸収体（実施の形態例１）を用いた熱型赤外線センサのセンサチップの平面図、図２は同センサチップの縦断面図、図３は本発明に係る赤外線吸収体（実施の形態例１）の作用説明図である。
【００３３】
本発明に係る赤外線吸収体Ｆは、一方の金属薄膜である第１の金属薄膜１と、他方の金属薄膜である第２の金属薄膜２と、これら第１、第２の金属薄膜１、２間に介装された絶縁膜３とから構成してあり、第１、第２の金属薄膜１、２は熱的に結合し、電気的には接触しない構造にしてある。
【００３４】
第１、第２の金属薄膜１、２としては、例えばＡｕの薄膜が用いられており、絶縁膜３としては、赤外線を吸収しやすい性質を有するもの、例えば、酸化シリコン（ＳｉＯ２ ）が用いられる。そして、第１、第２の金属薄膜１、２の膜厚は、単層での吸収率が最大０．５（５０％）となる膜厚にしてある（Ａｕを用いた場合、膜厚は約１７０Åにしてある（文献名：Ａｂｓｏｒｂｉｎｇ Ｌａｙｅｒｓ ｔｈｃｒｍａｌ Ｉｎｆｒａｒｅｄ Ｄｅｔｅｃｔｏｒｓ、ｐ６３５〜６３８参照）。
【００３５】
また、ここで用いた絶縁膜３は酸化シリコン（ＳｉＯ２ ）などのように赤外線の透過率が高いものであって、その膜厚も、第１、第２の金属薄膜１、２の膜厚程度にしてある。
【００３６】
次に、上記のように構成された赤外線吸収体Ｆの赤外線吸収の挙動を、図３を参照して説明する。
【００３７】
第１の金属薄膜１による赤外線透過光をＤ１、第１の金属薄膜１による赤外線反射光をＲ１、赤外線透過光Ｄ１のうち第２の金属薄膜２による赤外線透過光をＤ２、赤外線透過光Ｄ１のうち第２の金属薄膜２による赤外線反射光をＲ２、赤外線反射光Ｒ２のうち第１の金属薄膜１による赤外線透過光をＤ３、赤外線反射光Ｒ２のうち第１の金属薄膜１による赤外線反射光をＲ３とした場合において、赤外線入射光イを（≒１）とすると、第１の金属薄膜１に吸収された赤外線吸収光Ａ１は、
Ａ１≒｛１−（Ｄ１＋Ｒ１）｝＋｛Ｒ２−（Ｄ３＋Ｒ３）｝
である。この場合。｛１−（Ｄ１＋Ｒ１）｝は直接入射した赤外線入射光であり、｛Ｒ２−（Ｄ３＋Ｒ３）｝は第２の金属薄膜２による赤外線反射光である。
【００３８】
また、第２の金属薄膜２により吸収された赤外線吸収光Ａ２は、
Ａ２≒Ｄ１−（Ｄ２＋Ｒ２）
である。
【００３９】
よって、赤外線吸収体Ｆのトータル吸収量Ａは、
Ａ＝Ａ１＋Ａ２＝１−（Ｄ２＋Ｄ３＋Ｒ１＋Ｒ３）
となる。
【００４０】
そして、赤外線吸収体Ｆにおいて、入射赤外線量を１００％とすると、まず赤外線吸収体Ｆに到達した赤外線イは、第１の金属薄膜１により５０％が吸収される。残りの５０％の赤外線イは第１の金属薄膜１により２５％が赤外線反射光（Ｒ１）として反射され、残り２５％は赤外線透過光（Ｄ１）として透過される。
【００４１】
赤外線透過光（Ｄ１）は第２の金属薄膜２に到達し、１２．５％が吸収（Ａ２）される。さらに、約６％の赤外線が第２の金属薄膜２で反射（Ｒ２）され、第１の金属薄膜１によりさらに約３％の赤外線が吸収される。
【００４２】
このように、赤外線の赤外線吸収体Ｆによる反射を１回反射まで考えても、２層構造では、赤外線入射量のうち約６５％が吸収され、従来の単層での赤外線の吸収率５０％の約１．３倍となる。
【００４３】
ここでは、第１、第２の金属薄膜１、２を同じ膜厚で形成したが、それぞれの膜厚が違ってもよい。また、面積も同じでなくてもよい。また、赤外線吸収体Ｆは３層以上の多層構造でもよい。上記した本発明の実施の形態例１と同様な赤外線吸収体Ｆを３層構造として計算すると、赤外線の吸収は約７０％となり、単層の吸収率５０％の約１．４倍になる。また、各層の赤外線吸収率、反射率、透過率を、［表１］のように設計すれば吸収率が最大となる。
【００４４】
【表１】

Figure 0003608427
【００４５】
上記のように構成された赤外線吸収体Ｆは、熱型赤外線センサ（サーモパイルセンサ）のセンサチップＧの受光部分を形成している。このセンサチップＧはシリコン製の半導体基板１０上にメンブレン１１を結合して構成してある。このメンブレン１１は一方の誘電薄膜１２上に形成した複数個（１１個）の熱電対（サーモパイル）１３を直列に接続し、且つこれら複数個の熱電対１３を十字状に配置して各熱電対１３の温接点部（測温接点）１４を中心側に配し各熱電対１３の冷接点部（基準接点）１５を外側に配し、且つ２つの端子部１６、１７を形成し、これらの熱電対１３を他方の誘電薄膜１８で被覆して構成してある（図１２参照）。
【００４６】
そして、熱電対１３は異種金属、例えばＢｉ製の線材１９とＳｂ製の線材２０とから構成してあり、温接点部１４及び冷接点部１５は両線材１９、２０を重ね合わせて構成してある。
【００４７】
そして、受光部分である赤外線吸収体Ｆの形成はメンブレン１１上に第２の金属薄膜２を蒸着などによりＡｕなどで形成し、その上にＳｉＯ２ などの絶縁膜３を形成し、さらに、その上に第１の金属薄膜１を蒸着などによりＡｕなど
で形成して行われている。この場合、センサチップＧの各熱電対１３の温接点部１４が赤外線吸収体Ｆに覆われている。
【００４８】
したがって、受光部分である赤外線吸収体Ｆは上記したように２層構造では、赤外線入射量のうち約６５％を吸収する。この赤外線吸収体Ｆが吸収した赤外線の熱エネルギーはセンサチップＧの各熱電対１３の温接点部１４を加熱し、温接点部（測温接点）１４と冷接点部（基準接点）１５との間に温度差を与えて各熱電対１３に起電力を生じさせる。これらの起電力を端子部１６、１７より取出して、物体から放射される熱放射エネルギーを測定する。
【００４９】
上記した本発明の実施の形態例１によれば、赤外線吸収体Ｆは、第１の金属薄膜１と第２の金属薄膜２との間に絶縁膜３を介在させて、第１、第２の金属薄膜１、２間を絶縁すると共に、第１、第２の金属薄膜１、２を熱的に接続することが可能になり、第１の金属薄膜１を透過した赤外線は、第２の金属薄膜２で吸収でき、第２の金属薄膜２で反射した赤外線を第１の金属薄膜１で吸収できるため、単層時の金属薄膜に比べより多くの赤外線を吸収できる。
【００５０】
また、上記したセンサチップＧを用いた熱型赤外線センサは、赤外線吸収体Ｆの第１の金属薄膜１を透過した赤外線を、第２の金属薄膜２で吸収でき、第２の金属薄膜２で反射した赤外線を第１の金属薄膜１で吸収できるため、単層時の金属薄膜に比べより多くの赤外線を吸収できる。
【００５１】
このように吸収率の増加に比例してセンサ出力が向上するために、感度が向上し、周囲の温度のふらつきによる雑音も軽減できるために、センサの精度が向上する（外乱である周囲温度の影響が小さくなる）。また、熱型赤外線センサが安価に製造可能になる。
【００５２】
また、絶縁膜３の膜厚と第１、第２の金属薄膜１、２との膜厚を同程度にすることにより、熱型赤外線センサの赤外線吸収エリアの熱容量（Ｈ）の増加及び熱伝導率（Ｇ）の低下を最小限にすることができて、応答速度（τ＝Ｈ／Ｇ）を赤外線吸収体が単層の場合と同じにできる。
【００５３】
また、絶縁膜３は、赤外線透過率が高く、熱容量の小さい材料で構成すると、この絶縁膜３による吸収損失を最小限にできるし、この絶縁膜３の吸収損失を無視できるために設計が容易になる。
【００５４】
また、赤外線吸収体Ｆを２層構造とし、第１の金属薄膜１は赤外線反射率よりも赤外線透過率を多くし、第２の金属薄膜２は赤外線透過率よりも赤外線反射率を大きくすることは可能である。
【００５５】
この場合、より多くの赤外線が第２の金属薄膜２に到達するようになるし、また、第２の金属薄膜２は透過よりも反射が多くなるため、より多くの赤外線を反射し、赤外線反射光は再び第１の金属薄膜１で吸収される。その結果、赤外線吸収率は最大で０．５（５０％）（単層時）→０．７（７０％）に向上する（表１参照）。
【００５６】
また、赤外線吸収体Ｆを３層以上の多層構造とし、最終段の金属薄膜以外は赤外線反射率よりも赤外線透過率を多くし、最終段の金属薄膜は赤外線透過率よりも赤外線反射率を大きくすることも可能である。
【００５７】
この場合、膜構成を多くするほど赤外線吸収率は向上する。３層構成で赤外線吸収率は最大で０．５（５０％）（単層時）→０．８（８０％）に向上する（表１参照）。
【００５８】
（実施の形態例２）
本発明に係る赤外線吸収体の実施の形態例２を図４及び図５に示す。
図４は本発明に係る赤外線吸収体（実施の形態例２）を用いた熱型赤外線センサのセンサチップの平面図、図５は同センサチップの縦断面図である。なお、上記した本発明の実施の形態例１と同じ部品には同じ符号を付す。
【００５９】
本発明の実施の形態例２では、赤外線吸収体Ｆ−１を、メンブレン１１の他方の誘電薄膜１８上に第１の金属薄膜１を蒸着などによりＡｕなどで形成し、メンブレン１１の一方の誘電薄膜１２に第２の金属薄膜２を蒸着などによりＡｕなどで形成して構成し、本発明の実施の形態例１における絶縁膜３を無くしたものである。この場合、熱型赤外線センサのセンサチップＧの各熱電対１３の温接点部１４が赤外線吸収体Ｆ−１の第１、第２の金属薄膜１、２に覆われている。そして、この赤外線吸収体Ｆ−１は熱型赤外線センサ（サーモパイルセンサ）の受光部分を形成している。
【００６０】
このように構成された赤外線吸収体Ｆ−１の赤外線吸収の挙動は、本発明の実施の形態例１の赤外線吸収体Ｆの場合と同様である。この場合、熱電対１３の配線部分の占める割合が小さいので、この配線部分の熱的な損失は微小である。
【００６１】
また、受光部分である赤外線吸収体Ｆ−１は、２層構造では、赤外線入射量のうち約６５％が吸収する。この赤外線吸収体Ｆ−１が吸収した赤外線の熱エネルギーは熱型赤外線センサのセンサチップＧの各熱電対１３の温接点部１４を加熱し、温接点部（測温接点）１４と冷接点部（基準接点）１５との間に温度差を与えて各熱電対１３に起電力を生じさせる。これらの起電力を端子部１６、１７より取出して、物体から放射される熱放射エネルギーを測定する。
【００６２】
上記した本発明の実施の形態例２によれば、赤外線吸収体Ｆ−１を、第１の金属薄膜１をメンプレン１１の他方の誘電薄膜１８上に形成し、第２の金属薄膜２をメンプレン１１の一方の誘電薄膜１２上に形成して構成することにより、絶縁膜３を無くすことできて、熱型赤外線センサＧの受光部の構成を簡略化することができる。
【００６３】
（実施の形態例３）
本発明に係る赤外線吸収体の実施の形態例３を図６及び図７に示す。
図６は本発明に係る赤外線吸収体（実施の形態例３）を用いた熱型赤外線センサのセンサチップの平面図、図７は同センサチップの縦断面図である。なお、上記した本発明の実施の形態例１と同じ部品には同じ符号を付す。
【００６４】
本発明の実施の形態例３では、赤外線吸収体Ｆ−２は、熱型赤外線センサのセンサチップＧの感温部、すなわち、各熱電対１３の温接点部１４上のみに形成された部分赤外線吸収部４を有している。この部分赤外線吸収部４の構成は本発明の実施の形態例１における赤外線吸収体Ｆと同構成であって、金属薄膜の２層構造にしてある。すなわち、部分赤外線吸収部４は第１、第２の金属薄膜１、２と、これら第１、第２の金属薄膜１、２間に介装された絶縁膜３とから構成してあり、第１、第２の金属薄膜１、２は熱的に結合し、電気的には接触しない構造にしてある。第１、第２の金属薄膜１、２としては、例えばＡｕの薄膜が用いられており、絶縁膜３としては、赤外線を吸収しやすい性質を有するもの、例えば、酸化シリコン（ＳｉＯ２ ）が用いられる。
【００６５】
第１、第２の金属薄膜１、２の膜厚は、単層での吸収率が最大０．５（５０％）となる膜厚とする（Ａｕを用いた場合、膜厚は約１７０Åにしてある。）。また、ここで用いた絶縁膜３は酸化シリコン（ＳｉＯ２ ）などのように赤外線の透過率が高いものであり、その膜厚も、第１、第２の金属薄膜１、２の膜厚程度にしてある。
【００６６】
そして、赤外線吸収体Ｆ−２の赤外線吸収の挙動は、各熱電対１３の温接点部１４上のみにおいて、本発明の実施の形態例１に場合と同様である。
【００６７】
上記した本発明の実施の形態例３によれば、サーモパイルセンサのように受光部が感温部、すなわち温接点部１４上にのみでよい場合、温接点部１４上に部分赤外線吸収部４を形成することで、受光部全体の熱容量を小さくでき、その結果、応答速度が早くなる。
【００６８】
（実施の形態例４）
本発明に係る赤外線吸収体の実施の形態例４を図８及び図９に示す。
図８は本発明に係る赤外線吸収体（実施の形態例４）の断面図、図９は同赤外線吸収体を用いた熱型赤外線センサの縦断面図である。なお、上記した本発明に係る赤外線吸収体の実施の形態例１と同じ部品には同じ符号を付す。
【００６９】
本発明に係る赤外線吸収体Ｆ−３を用いたセンサチップＧをセンサパッケージ３１に収容して熱型赤外線センサＳを構成した場合、このセンサパッケージ３１に設けた窓部３２の大きさから入射赤外線の範囲は２θである。
【００７０】
そして、赤外線吸収体Ｆ−３の構成は、金属薄膜の２層構造にしてある。すなわち、赤外線吸収体Ｆ−３は第１、第２の金属薄膜１、２と、これら第１、第２の金属薄膜１、２間に介装された絶縁膜３とから構成してあり、第１、第２の金属薄膜１、２は熱的に結合し、電気的には接触しない構造にしてある。第１、第２の金属薄膜１、２としては、例えばＡｕの薄膜が用いられており、絶縁膜３としては、赤外線を吸収しやすい性質を有するもの、例えば、酸化シリコン（ＳｉＯ ２ ）が用いられる。
【００７１】
第１、第２の金属薄膜１、２の膜厚は、単層での吸収率が最大０．５（５０％）となる膜厚とする（Ａｕを用いた場合、膜厚は約１７０Åにしてある。）。また、ここで用いた絶縁膜３は酸化シリコン（ＳｉＯ２ ）などのように赤外線の透過率が高いものであり、その膜厚も、第１、第２の金属薄膜１、２の膜厚程度にしてある。
【００７２】
そして、赤外線の入射方向に、第１の金属薄膜１と第２の金属薄膜２とが、この順序で配置してあって、第２の金属薄膜２の面積は第１の金属薄膜１の面積より大きくしてある。このために、第１の金属薄膜１が第２の金属薄膜２を覆っていない直接入射箇所２Ａが生じている。
【００７３】
このような赤外線吸収体Ｆ−３の構成において、赤外線入射光には、図８に示すように第１、第２の金属薄膜１、２に入射する赤外線入射光ａと、第２の金属薄膜２に直接入射して、その赤外線反射光が第１の金属薄膜１に入射する赤外線入射光ｂと、第２の金属薄膜２に直接入射する赤外線入射光ｃとが存在する。
【００７４】
赤外線入射光ａの場合は、本発明の実施の形態例１に場合と同様であって、図３に示すように入射赤外線量を１００％とすると、まず赤外線吸収体Ｆ−３に到達した赤外線イは、第１の金属薄膜１により５０％が吸収される。残りの５０％の赤外線イは第１の金属薄膜１により２５％が赤外線反射光（Ｒ１）として反射され、残り２５％は赤外線透過光（Ｄ１）として透過される。
【００７５】
赤外線透過光（Ｄ１）は第２の金属薄膜２に到達し、１２．５％が吸収（Ａ２）される。さらに、約６％の赤外線が第２の金属薄膜２で反射（Ｒ２）され、第１の金属薄膜１によりさらに約３％の赤外線が吸収される。
【００７６】
このように、赤外線の赤外線吸収体Ｆ−３による反射を１回反射まで考えても、２層構造では、赤外線入射量の内約６５％が吸収され、従来の単層での赤外線の吸収率５０％の約１．３倍となる。
【００７７】
また、赤外線入射光ｂの場合は、第２の金属薄膜２の直接入射箇所２Ａに直接入射してこの第２の金属薄膜２に吸収され、第２の金属薄膜２による入射赤外線の反射光のうち、メンブレン１１に対して垂直でない方向の赤外線反射光をより多く第１の金属薄膜１に入射するようにしてある。例えば、図８に示すように入射角θで第１の金属薄膜１に入射した入射赤外線ロの反射光ロ´は、より多く第１の金属薄膜１に入射される。
【００７８】
また、赤外線入射光ｃの場合は、第２の金属薄膜２の直接入射箇所２Ａに直接入射してこの第２の金属薄膜２に吸収され、第２の金属薄膜２による入射赤外線ハの反射光は第１の金属薄膜１に入射しない。
【００７９】
上記した本発明の実施の形態例４によれば、第２の金属薄膜２の面積は第１の金属薄膜１の面積より大きくしてあるために、第１の金属薄膜１が第２の金属薄膜２を覆っていない箇所、すなわち直接入射箇所２Ａが生じ、この直接入射箇所２Ａに直接に入射した入射赤外線を第２の金属薄膜２で吸収し、この第２の金属薄膜２による入射赤外線ロの反射光ロ´のうち、メンブレン１１に対して垂直でない方向の反射光をより多く第１の金属薄膜１に入射することができる。このために、単層時の金属薄膜に比べより多くの赤外線を吸収できる。
【００８０】
【発明の効果】
以上説明したように、請求項１の発明に係る赤外線吸収体によれば、隣り合う金属薄膜間を絶縁すると共に、隣り合う金属薄膜を熱的に接続することが可能になり、隣り合う金属薄膜のうち、一方の金属薄膜を透過した赤外線は、他方の金属薄膜で吸収でき、他方の金属薄膜で反射した赤外線を一方の金属薄膜で吸収できるために、単層時の金属薄膜に比べより多くの赤外線を吸収することができる。このように赤外線吸収率が高く、且つ高速応答性を持ち、低コストで生産が容易な赤外線吸収体を提供することができる。
【００８１】
また、請求項１の発明に係る赤外線吸収体によれば、隣り合う金属薄膜間を絶縁すると共に、隣り合う金属薄膜を熱的に接続することが可能になり、隣り合う金属薄膜のうち、一方の金属薄膜を透過した赤外線は、他方の金属薄膜で吸収でき、他方の金属薄膜で反射した赤外線を一方の金属薄膜で吸収できるために、単層時の金属薄膜に比べより多くの赤外線を吸収することができる。
【００８２】
しかも、多層構造における最終段の金属薄膜は、その赤外線透過率よりも赤外線反射率を大きくし、最終段の金属薄膜以外の金属薄膜は、その赤外線反射率よりも赤外線透過率を大きくしてあるために、より多くの赤外線が最終段の金属薄膜に到達し、この最終段の金属薄膜はより多くの赤外線を反射し、反射光は再び最終段の金属薄膜以外の金属薄膜で吸収されて、赤外線吸収率が向上する。例えば、２層構造の赤外線吸収体であれば、赤外線吸収率は０．５（単層時）から０．７に向上するし、３層構造の赤外線吸収体であれば、赤外線吸収率は０．５（単層時）から０．８に向上する。
【００８３】
また、請求項２の発明に係る赤外線吸収体によれば、請求項１の発明の作用効果と同様な作用効果を奏し得るばかりか、他方の金属薄膜の面積は一方の金属薄膜の面積より大きくしてあり、一方の金属薄膜が他方の金属薄膜を覆っていない赤外線の直接入射箇所では、入射赤外線を直接に他方の金属薄膜で吸収し、また、他方の金属薄膜による入射赤外線の反射光のうち垂直でない方向の反射光をより多く一方の金属薄膜に入射することができる。このために、単層時の金属薄膜に比べより多くの赤外線を吸収できる。
【００８４】
また、請求項３の発明に係る熱型赤外線センサによれば、赤外線吸収体の一方の金属薄膜を透過した赤外線を、他方の金属薄膜で吸収でき、他方の金属薄膜で反射した赤外線を一方の金属薄膜で吸収できるために、単層時の金属薄膜に比べより多くの赤外線を吸収できる。このように吸収率の増加に比例してセンサ出力が向上するために、感度が向上し、周囲の温度のふらつきによる雑音も軽減できるためにセンサの精度が向上する。このように、赤外線吸収率が高く、且つ高速応答性を持ち、低コストで生産が容易な赤外線吸収体を用いた熱型赤外線センサを提供することができる。
【００８５】
しかも、多層構造における最終段の金属薄膜は、その赤外線透過率よりも赤外線反射率を大きくし、最終段の前記金属薄膜以外の金属薄膜は、その赤外線反射率よりも赤外線透過率を大きくしてあるために、より多くの赤外線が最終段の金属薄膜に到達し、この最終段の金属薄膜はより多くの赤外線を反射し、反射光は再び最終段の金属薄膜以外の金属薄膜で吸収されて、赤外線吸収率が向上する。例えば、２層構造の赤外線吸収体であれば、赤外線吸収率は０．５（単層時）から０．７に向上するし、３層構造の赤外線吸収体であれば、赤外線吸収率は０．５（単層時）から０．８に向上する。
【００８６】
また、請求項３の発明に係る熱型赤外線センサによれば、赤外線吸収体の一方の金属薄膜を透過した赤外線を、他方の金属薄膜で吸収でき、他方の金属薄膜で反射した赤外線を一方の金属薄膜で吸収できるために、単層時の金属薄膜に比べより多くの赤外線を吸収できる。このように吸収率の増加に比例してセンサ出力が向上するために、感度が向上し、周囲の温度のふらつきによる雑音も軽減できるために、センサの精度が向上する。また、熱型赤外線センサが安価に製造可能になる。
【００８７】
このように、赤外線吸収率が高く、且つ高速応答性を持ち、低コストで生産が容易な赤外線吸収体を用いた熱型赤外線センサを提供することができる。
【００８８】
また、請求項４の発明に係る熱型赤外線センサによれば、請求項３の発明の作用効果と同様な作用効果を奏し得るばかりか、一方の金属薄膜をメンブレンの一方の面に形成し、他方の金属薄膜をメンブレンの他方の面に形成することにより絶縁膜を無くすことができて、熱型赤外線センサの受光部の構成を簡略化することができる。
【００８９】
また、請求項５の発明に係る熱型赤外線センサによれば、請求項３の発明の作用効果と同様な作用効果を奏し得るばかりか、サーモパイルセンサのように受光部が感温部、すなわち温接点部上にのみでよい場合、温接点部上に部分赤外線吸収部を形成することで、受光部全体の熱容量を小さくでき、その結果、応答速度が早くなる。
【図面の簡単な説明】
【図１】本発明に係る赤外線吸収体（実施の形態例１）を用いた熱型赤外線センサのセンサチップの平面図である。
【図２】同センサチップの縦断面図である。
【図３】本発明に係る赤外線吸収体（実施の形態例１）の作用説明図である。
【図４】本発明に係る赤外線吸収体（実施の形態例２）を用いた熱型赤外線センサのセンサチップの平面図である。
【図５】同センサチップの縦断面図である。
【図６】本発明に係る赤外線吸収体（実施の形態例３）を用いた熱型赤外線センサのセンサチップの平面図である。
【図７】同センサチップの縦断面図である。
【図８】本発明に係る赤外線吸収体（実施の形態例４）の断面図である。
【図９】同赤外線吸収体を用いた熱型赤外線センサの縦断面図である。
【図１０】従来の赤外線吸収体を用いた熱型赤外線センサのセンサチップの平面図である。
【図１１】同センサチップの縦断面図である。
【図１２】赤外線吸収体を除いた状態のセンサチップの平面図である。
【符号の説明】
１ 第１の金属薄膜（一方の金属薄膜）
２ 第２の金属薄膜（他方の金属薄膜）
３ 絶縁膜
４ 部分赤外線吸収部
１０ 半導体基板
１１ メンブレン
１２ 一方の誘電薄膜
１３ 熱電対
１４ 温接点部（測温接点）（感温部）
１５ 冷接点部（基準接点）
１６ 端子部
１７ 端子部
１８ 他方の誘電薄膜
１９ 線材
２０ 線材
３１ センサパッケージ
３２ 窓部
Ｇ センサチップ
Ｆ 赤外線吸収体
Ｆ−１ 赤外線吸収体
Ｆ−２ 赤外線吸収体
Ｆ−３ 赤外線吸収体
Ｓ 熱型赤外線センサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an infrared absorber and a thermal infrared sensor using the infrared absorber.
[0002]
[Prior art]
Infrared absorbers are often used in thermal infrared sensors, and incident infrared energy from the outside is converted into heat by the infrared absorber, and the heat is converted into electric signals by the thermal infrared sensor.
[0003]
Conventionally, infrared absorbers for converting incident infrared rays into heat include (1) those formed by a method of vapor-depositing metal with a thickness that does not flow electricity, (2) gold black, (3) (2) Carbon paste coating film (4) Some films are formed by plating platinum or the like by plating.
[0004]
In (1), when the film thickness of the metal thin film is set to such a level that electricity does not flow, when infrared rays are incident on the metal thin film, electrons in the metal thin film vibrate and the energy is converted into heat. The infrared absorptivity of this metal thin film becomes the maximum at the film thickness at which the infrared reflectance and transmittance are equal, and the maximum value is theoretically O.D. 5 (50%) is low. However, there is an advantage that a normal vapor deposition apparatus can be easily manufactured and the response speed is fast because the heat capacity is small (refer to literature title: Zeitshift fur Physik, volume: vol91, pp230-251, publication year: 1934).
[0005]
As shown in FIGS. 10 and 11, (1) the infrared absorber 9 formed by a method of depositing metal with a thickness that does not allow electricity to flow is the sensor chip G of the thermal infrared sensor (thermopile sensor). A light receiving portion is formed. The sensor chip G is configured by bonding a membrane 11 on a silicon semiconductor substrate 10. Then, as shown in FIG. 12, the membrane 11 has a plurality (11 pieces) of thermocouples (thermopiles) 13 formed on one dielectric thin film 12 connected in series, and the plurality of thermocouples 13 are connected to each other. Arranged in a cross shape, the hot junction part (temperature measuring contact) 14 of each thermocouple 13 is arranged on the center side, the cold junction part (reference contact) 15 of each thermocouple 13 is arranged on the outside, and two terminal parts 16 and 17 are formed, and these thermocouples 13 are covered with the other dielectric thin film 18.
[0006]
The thermocouple 13 is composed of dissimilar metals, for example, a wire 19 made of Bi and a wire 20 made of Sb, and the hot junction portion 14 and the cold junction portion 15 are constructed by superimposing both wires 19 and 20. is there.
[0007]
The infrared absorber 9 as a light receiving portion is formed by depositing a metal thin film on the membrane 11.
[0008]
[Problems to be solved by the invention]
Materials with good absorption efficiency include (2) gold black, (3) carbon paste coating film, (4) platinum coating by plating, etc. (2) Low vacuum deposition equipment is used to form gold black. It is necessary, and the formed infrared absorber has a problem that its strength is weak.
[0009]
(3) The carbon paste coating film is easy to pattern on the infrared sensor, but has no chemical resistance to chemicals for anisotropic etching of the substrate (Si) forming the infrared sensor. There was a problem that production became difficult.
[0010]
In addition, (4) a platinum film by plating also requires a dedicated device, and there is a problem that the material is expensive.
[0011]
In addition, since these materials have large heat capacities, there is a problem that the response speed is slower than that of the metal thin film. (When a metal thin film is used for the infrared absorber, the time constant is about half that of gold black or resin material).
[0012]
In addition, (1) In the infrared absorber 9 formed by the method of vapor-depositing a metal with a thickness that does not allow electricity to flow, the metal thin film can be easily produced and can be formed at low cost. The infrared absorptivity is as low as 0.5 (50%). In order to form another infrared absorber having a high infrared absorptivity, a dedicated device is required, and the cost of the material is high.
[0013]
The present invention has been made paying attention to the above-mentioned problems. The first object of the present invention is to provide an infrared ray having a high infrared absorption rate, a high speed response, and low cost and easy to produce. It is to provide an absorber.
[0014]
A second object of the present invention is to provide a thermal infrared sensor using an infrared absorber that has a high infrared absorptance, has high-speed response, and is easy to produce at low cost. .
[0015]
[Means for Solving the Problems]
In order to achieve the above first object, an infrared absorber according to the invention of claim 1 is an infrared absorber for converting the energy of incident infrared rays from the outside into heat, and includes at least two or more infrared absorbers. Having a metal thin film and adjacent to it Said Multi-layer structure with insulating film between metal thin films Each of the metal thin films in the multilayer structure is an infrared absorber, and is composed of a thin film having a maximum infrared absorption rate of 0.5 (50%) in a single layer and capable of being insulated from each other. The infrared reflectance is made larger than the infrared transmittance in the thin film, and the infrared transmittance is made larger than the infrared reflectance in the metal thin film other than the metal thin film in the final stage. Is.
[0016]
With this configuration, it is possible to insulate adjacent metal thin films and to thermally connect adjacent metal thin films, and among the adjacent metal thin films, infrared rays transmitted through one metal thin film are transmitted to the other metal thin film. Since it can be absorbed by a thin film and the infrared light reflected by the other metal thin film can be absorbed by one metal thin film, more infrared light can be absorbed than a metal thin film in a single layer. As described above, it is possible to provide an infrared absorber that has a high infrared absorption rate, has high-speed response, and is easy to produce at low cost.
[0018]
Also, With this configuration, it is possible to insulate adjacent metal thin films and to thermally connect adjacent metal thin films, and among the adjacent metal thin films, infrared rays transmitted through one metal thin film are transmitted to the other metal thin film. Since it can be absorbed by a thin film and the infrared light reflected by the other metal thin film can be absorbed by one metal thin film, more infrared light can be absorbed than a metal thin film in a single layer.
[0019]
In addition, the metal thin film at the final stage in the multilayer structure has an infrared reflectance greater than its infrared transmittance, and the metal thin film other than the metal thin film at the final stage has an infrared transmittance greater than its infrared reflectance. For this reason, more infrared rays reach the final stage metal thin film, this final stage metal thin film reflects more infrared rays, and the reflected light is again absorbed by metal thin films other than the final stage metal thin film. Infrared absorption rate is improved. For example, if the infrared absorber has a two-layer structure, the infrared absorption rate is improved from 0.5 (single layer) to 0.7, and if the infrared absorber has a three-layer structure, the infrared absorption rate is 0. From 0.5 (single layer) to 0.8.
[0020]
In order to achieve the first object, the claims 2 The infrared absorber according to the invention is an infrared absorber for converting the energy of incident infrared rays from the outside into heat, and an insulating film is interposed between one metal thin film and the other metal thin film, and In the direction of incidence of infrared rays Said With one metal thin film Said Arrange the other metal thin film in this order, Said The area of the other metal thin film Said Larger than the area of one metal thin film, Said The other metal thin film is provided with a direct incident portion of infrared rays.
[0021]
With this configuration, not only can the same effect as the effect of the invention of claim 1 be obtained, but the area of the other metal thin film is larger than the area of one metal thin film, and one metal thin film is the other metal. In the direct incident part of the infrared rays not covering the thin film, the incident infrared ray is directly absorbed by the other metal thin film, and more of the reflected light of the incident infrared ray by the other metal thin film is reflected in a non-perpendicular direction. It can be incident on a metal thin film. For this reason, more infrared rays can be absorbed compared with the metal thin film at the time of a single layer.
[0022]
In order to achieve the second object, a claim is provided. 3 The thermal infrared sensor according to the invention has an infrared absorber having at least two metal thin films and adjacent to each other. Said A multilayer structure is formed by interposing an insulating film between metal thin films. The metal thin films in the multilayer structure are both thin films having a maximum infrared absorption rate of 0.5 (50%) in a single layer and can be insulated from each other, and the infrared transmittance of the final stage metal thin film. The infrared reflectance is made larger than that of the metal thin film other than the final stage metal thin film, and the infrared transmittance is made larger than the infrared reflectance of the metal thin film. The light receiving part is used.
[0023]
With this configuration, the infrared light transmitted through one metal thin film of the infrared absorber can be absorbed by the other metal thin film, and the infrared light reflected by the other metal thin film can be absorbed by the one metal thin film. More infrared rays can be absorbed. Since the sensor output is improved in proportion to the increase in the absorption rate in this way, the sensitivity is improved, and noise due to fluctuations in the ambient temperature can be reduced, so that the accuracy of the sensor is improved. As described above, it is possible to provide a thermal infrared sensor using an infrared absorber that has a high infrared absorptivity, has high-speed response, and is easy to produce at low cost.
[0024]
In addition, the metal thin film at the final stage in the multilayer structure has an infrared reflectance greater than its infrared transmittance, and the metal thin film other than the metal thin film at the final stage has an infrared transmittance greater than its infrared reflectance. For this reason, more infrared rays reach the final stage metal thin film, this final stage metal thin film reflects more infrared rays, and the reflected light is again absorbed by metal thin films other than the final stage metal thin film. Infrared absorption rate is improved. For example, if the infrared absorber has a two-layer structure, the infrared absorption rate is improved from 0.5 (single layer) to 0.7, and if the infrared absorber has a three-layer structure, the infrared absorption rate is 0. From 0.5 (single layer) to 0.8.
[0027]
In order to achieve the second object, a claim is provided. 4 The thermal infrared sensor according to the invention of claim 3 In the thermal infrared sensor according to claim 1, an insulating film Is A membrane in which a thermocouple is enclosed in a dielectric thin film.
[0028]
With this configuration, the claims 3 In addition to having the same effect as that of the present invention, one metal thin film is formed on one surface of the membrane, and the other metal thin film is formed on the other surface of the membrane, thereby eliminating the insulating film. Thus, the configuration of the light receiving part of the thermal infrared sensor can be simplified.
[0029]
In order to achieve the second object, a claim is provided. 5 The thermal infrared sensor according to the invention has an infrared absorber having at least two metal thin films. , And its neighbors Said Insulating film between metal thin films The Multilayer structure In addition, both the metal thin films in the multi-layer structure are composed of thin films having a maximum infrared absorption rate of 0.5 (50%) in a single layer and can be insulated from each other, and the infrared transmittance of the final stage metal thin film The infrared reflectance is made larger than that of the metal thin film other than the final stage metal thin film, and the infrared transmittance is made larger than the infrared reflectance of the metal thin film. Consists of a partial infrared absorption part, and the partial infrared absorption part is on the temperature sensitive part. of Formed only The The light receiving part is used.
[0030]
With this configuration, the claims 3 In addition to the effects similar to those of the present invention, when the light receiving part only needs to be on the temperature sensitive part, i.e., the hot junction part as in the case of a thermopile sensor, a partial infrared ray absorbing part is formed on the hot junction part. By doing so, the heat capacity of the entire light receiving unit can be reduced, and as a result, the response speed is increased.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0032]
(Embodiment 1)
Embodiment 1 of an infrared absorber according to the present invention is shown in FIGS.
FIG. 1 is a plan view of a sensor chip of a thermal infrared sensor using an infrared absorber according to the present invention (Embodiment 1), FIG. 2 is a longitudinal sectional view of the sensor chip, and FIG. 3 is an infrared ray according to the present invention. It is operation | movement explanatory drawing of an absorber (Embodiment example 1).
[0033]
The infrared absorber F according to the present invention includes a first metal thin film 1 that is one metal thin film, a second metal thin film 2 that is the other metal thin film, and the first and second metal thin films 1 and 2. The first and second metal thin films 1 and 2 are thermally coupled to each other and are not in electrical contact with each other.
[0034]
As the first and second metal thin films 1 and 2, for example, Au thin films are used, and as the insulating film 3, a material having a property of easily absorbing infrared rays, for example, silicon oxide (SiO 2 2 ) Is used. The film thicknesses of the first and second metal thin films 1 and 2 are such that the maximum absorption rate in a single layer is 0.5 (50%) (when Au is used, the film thickness is The thickness is about 170 mm (see literature name: Absorbing Layers infrared Infrared Detectors, p635-638).
[0035]
The insulating film 3 used here is silicon oxide (SiO 2). 2 ) And the like, and the film thickness is also set to about the film thickness of the first and second metal thin films 1 and 2.
[0036]
Next, the behavior of infrared absorption of the infrared absorber F configured as described above will be described with reference to FIG.
[0037]
The infrared transmitted light by the first metal thin film 1 is D1, the infrared reflected light by the first metal thin film 1 is R1, the infrared transmitted light by the second metal thin film 2 of the infrared transmitted light D1 is D2, and the infrared transmitted light D1 Among them, infrared reflected light by the second metal thin film 2 is R2, infrared transmitted light by the first metal thin film 1 is D3 among infrared reflected light R2, and infrared reflected light by the first metal thin film 1 is reflected by infrared reflected light R2. In the case of R3, when the infrared incident light A is (≈1), the infrared absorbed light A1 absorbed by the first metal thin film 1 is
A1≈ {1- (D1 + R1)} + {R2- (D3 + R3)}
It is. in this case. {1- (D1 + R1)} is directly incident infrared incident light, and {R2- (D3 + R3)} is infrared reflected light by the second metal thin film 2.
[0038]
Further, the infrared absorption light A2 absorbed by the second metal thin film 2 is
A2≈D1- (D2 + R2)
It is.
[0039]
Therefore, the total absorption amount A of the infrared absorber F is
A = A1 + A2 = 1− (D2 + D3 + R1 + R3)
It becomes.
[0040]
In the infrared absorber F, assuming that the amount of incident infrared rays is 100%, 50% of the infrared rays that have reached the infrared absorber F are first absorbed by the first metal thin film 1. The remaining 50% of infrared rays a are reflected by the first metal thin film 1 as 25% as infrared reflected light (R1), and the remaining 25% are transmitted as infrared transmitted light (D1).
[0041]
The infrared transmitted light (D1) reaches the second metal thin film 2 and 12.5% is absorbed (A2). Further, about 6% of infrared rays are reflected (R2) by the second metal thin film 2, and further about 3% of infrared rays are absorbed by the first metal thin film 1.
[0042]
Thus, even if reflection of infrared rays by the infrared absorber F is considered up to one reflection, in the two-layer structure, about 65% of the amount of incident infrared rays is absorbed, and the infrared absorption rate of a conventional single layer is 50%. It is about 1.3 times that of.
[0043]
Here, the first and second metal thin films 1 and 2 are formed with the same film thickness, but each film thickness may be different. Moreover, the area may not be the same. Further, the infrared absorber F may have a multilayer structure of three or more layers. When the infrared absorber F similar to that of the first embodiment of the present invention is calculated as a three-layer structure, the infrared absorption is about 70%, which is about 1.4 times the single layer absorption rate of 50%. Moreover, if the infrared absorptivity, reflectance, and transmittance of each layer are designed as shown in [Table 1], the absorptance is maximized.
[0044]
[Table 1]
Figure 0003608427
[0045]
The infrared absorber F configured as described above forms a light receiving portion of a sensor chip G of a thermal infrared sensor (thermopile sensor). The sensor chip G is configured by bonding a membrane 11 on a silicon semiconductor substrate 10. The membrane 11 has a plurality of (11) thermocouples (thermopiles) 13 formed on one dielectric thin film 12 connected in series, and the plurality of thermocouples 13 are arranged in a cross shape to form each thermocouple. 13 hot junctions (temperature measuring junctions) 14 are arranged on the center side, cold junctions (reference junctions) 15 of each thermocouple 13 are arranged on the outside, and two terminal parts 16 and 17 are formed. The thermocouple 13 is covered with the other dielectric thin film 18 (see FIG. 12).
[0046]
The thermocouple 13 is composed of dissimilar metals, for example, a wire 19 made of Bi and a wire 20 made of Sb, and the hot junction portion 14 and the cold junction portion 15 are constructed by superimposing both wires 19 and 20. is there.
[0047]
The infrared absorber F, which is the light receiving portion, is formed by forming the second metal thin film 2 on the membrane 11 by vapor deposition or the like, and then forming SiO on the second metal thin film 2. 2 An insulating film 3 such as Au is formed, and a first metal thin film 1 is further deposited thereon by vapor deposition or the like.
It is done by forming. In this case, the hot junction 14 of each thermocouple 13 of the sensor chip G is covered with the infrared absorber F.
[0048]
Therefore, as described above, the infrared absorber F as the light receiving portion absorbs about 65% of the amount of incident infrared rays in the two-layer structure. The infrared thermal energy absorbed by the infrared absorber F heats the hot contact portions 14 of the thermocouples 13 of the sensor chip G, and the hot contact portion (temperature measuring contact) 14 and the cold contact portion (reference contact) 15 An electromotive force is generated in each thermocouple 13 by providing a temperature difference therebetween. These electromotive forces are taken out from the terminal portions 16 and 17, and the thermal radiation energy radiated from the object is measured.
[0049]
According to the first embodiment of the present invention described above, the infrared absorber F includes the first and second insulating films 3 interposed between the first metal thin film 1 and the second metal thin film 2. The first and second metal thin films 1 and 2 can be thermally connected to each other, and the infrared rays transmitted through the first metal thin film 1 Since the infrared rays reflected by the second metal thin film 2 and reflected by the second metal thin film 2 can be absorbed by the first metal thin film 1, more infrared rays can be absorbed as compared to the metal thin film in a single layer.
[0050]
Further, the thermal infrared sensor using the sensor chip G described above can absorb the infrared light transmitted through the first metal thin film 1 of the infrared absorber F by the second metal thin film 2, and the second metal thin film 2 can absorb the infrared light. Since the reflected infrared rays can be absorbed by the first metal thin film 1, more infrared rays can be absorbed as compared to the metal thin film in a single layer.
[0051]
Since the sensor output improves in proportion to the increase in the absorption rate, the sensitivity is improved, and noise due to fluctuations in the ambient temperature can be reduced, so that the accuracy of the sensor is improved (the ambient temperature, which is a disturbance). The impact is reduced). In addition, the thermal infrared sensor can be manufactured at low cost.
[0052]
Further, by making the film thickness of the insulating film 3 and the film thicknesses of the first and second metal thin films 1 and 2 approximately the same, the heat capacity (H) of the infrared absorption area of the thermal infrared sensor is increased and the heat conduction. The reduction in the rate (G) can be minimized, and the response speed (τ = H / G) can be made the same as when the infrared absorber is a single layer.
[0053]
Further, if the insulating film 3 is made of a material having a high infrared transmittance and a small heat capacity, the absorption loss due to the insulating film 3 can be minimized, and the absorption loss of the insulating film 3 can be ignored, so that the design is easy. become.
[0054]
The infrared absorber F has a two-layer structure, the first metal thin film 1 has a higher infrared transmittance than the infrared reflectance, and the second metal thin film 2 has a higher infrared reflectance than the infrared transmittance. Is possible.
[0055]
In this case, more infrared rays reach the second metal thin film 2, and since the second metal thin film 2 is more reflective than transmitted, it reflects more infrared rays and reflects infrared rays. The light is again absorbed by the first metal thin film 1. As a result, the infrared absorptance is improved to 0.5 (50%) (single layer) → 0.7 (70%) at maximum (see Table 1).
[0056]
Further, the infrared absorber F has a multilayer structure of three or more layers, except for the final stage metal thin film, the infrared transmittance is greater than the infrared reflectance, and the final stage metal thin film has a greater infrared reflectance than the infrared transmittance. It is also possible to do.
[0057]
In this case, the infrared absorption rate is improved as the film configuration is increased. In the three-layer structure, the infrared absorption rate is improved to 0.5 (50%) (in the case of a single layer) → 0.8 (80%) at the maximum (see Table 1).
[0058]
(Embodiment 2)
Embodiment 2 of the infrared absorber according to the present invention is shown in FIGS.
FIG. 4 is a plan view of a sensor chip of a thermal infrared sensor using an infrared absorber according to the present invention (Embodiment 2), and FIG. 5 is a longitudinal sectional view of the sensor chip. In addition, the same code | symbol is attached | subjected to the same components as above-mentioned Embodiment 1 of this invention.
[0059]
In Embodiment 2 of the present invention, the infrared absorber F-1 is formed of Au or the like on the other dielectric thin film 18 of the membrane 11 by vapor deposition or the like, and one dielectric of the membrane 11 is formed. The second metal thin film 2 is formed on the thin film 12 by vapor deposition or the like using Au or the like, and the insulating film 3 in the first embodiment of the present invention is eliminated. In this case, the hot junction 14 of each thermocouple 13 of the sensor chip G of the thermal infrared sensor is covered with the first and second metal thin films 1 and 2 of the infrared absorber F-1. And this infrared rays absorber F-1 forms the light-receiving part of a thermal type infrared sensor (thermopile sensor).
[0060]
The infrared absorption behavior of the infrared absorber F-1 configured as described above is the same as that of the infrared absorber F of the first embodiment of the present invention. In this case, since the proportion of the wiring portion of the thermocouple 13 is small, the thermal loss of this wiring portion is very small.
[0061]
Further, in the infrared absorber F-1 which is a light receiving portion, about 65% of the amount of incident infrared rays is absorbed in the two-layer structure. The infrared thermal energy absorbed by the infrared absorber F-1 heats the hot contact portions 14 of the thermocouples 13 of the sensor chip G of the thermal infrared sensor, and warm contact portions (temperature measuring contacts) 14 and cold contact portions. An electromotive force is generated in each thermocouple 13 by giving a temperature difference to (reference contact) 15. These electromotive forces are taken out from the terminal portions 16 and 17, and the thermal radiation energy radiated from the object is measured.
[0062]
According to the second embodiment of the present invention described above, the infrared absorber F-1 is formed by forming the first metal thin film 1 on the other dielectric thin film 18 of the membrane 11 and the second metal thin film 2 as the membrane. 11 is formed on one of the dielectric thin films 12, the insulating film 3 can be eliminated, and the configuration of the light receiving portion of the thermal infrared sensor G can be simplified.
[0063]
(Embodiment 3)
Embodiment 3 of the infrared absorber according to the present invention is shown in FIGS.
FIG. 6 is a plan view of a sensor chip of a thermal infrared sensor using an infrared absorber (Embodiment 3) according to the present invention, and FIG. 7 is a longitudinal sectional view of the sensor chip. In addition, the same code | symbol is attached | subjected to the same components as above-mentioned Embodiment 1 of this invention.
[0064]
In the third embodiment of the present invention, the infrared absorber F-2 is a partial infrared ray formed only on the temperature sensing part of the sensor chip G of the thermal infrared sensor, that is, the hot junction part 14 of each thermocouple 13. It has an absorption part 4. The configuration of this partial infrared absorbing portion 4 is the same as that of the infrared absorber F in the first embodiment of the present invention, and has a two-layer structure of a metal thin film. That is, the partial infrared ray absorbing portion 4 is composed of first and second metal thin films 1 and 2 and an insulating film 3 interposed between the first and second metal thin films 1 and 2. The first and second metal thin films 1 and 2 are configured to be thermally coupled and not electrically contacted. As the first and second metal thin films 1 and 2, for example, Au thin films are used, and as the insulating film 3, a material having a property of easily absorbing infrared rays, for example, silicon oxide (SiO 2 2 ) Is used.
[0065]
The film thicknesses of the first and second metal thin films 1 and 2 are set so that the absorption rate in a single layer is a maximum of 0.5 (50%) (when Au is used, the film thickness is about 170 mm). ) The insulating film 3 used here is silicon oxide (SiO 2). 2 ) And the like, and the film thickness is also set to about the film thickness of the first and second metal thin films 1 and 2.
[0066]
And the infrared absorption behavior of the infrared absorber F-2 is the same as in the first embodiment of the present invention only on the hot junction 14 of each thermocouple 13.
[0067]
According to the above-described third embodiment of the present invention, when the light receiving part only needs to be on the temperature sensing part, that is, the warm contact part 14 as in the thermopile sensor, the partial infrared ray absorbing part 4 is provided on the warm contact part 14. By forming, the heat capacity of the entire light receiving unit can be reduced, and as a result, the response speed is increased.
[0068]
(Embodiment 4)
Embodiment 4 of the infrared absorber according to the present invention is shown in FIGS.
FIG. 8 is a sectional view of an infrared absorber (Embodiment 4) according to the present invention, and FIG. 9 is a longitudinal sectional view of a thermal infrared sensor using the infrared absorber. In addition, the same code | symbol is attached | subjected to the same components as Embodiment 1 of the infrared absorber which concerns on above-described this invention.
[0069]
In the case where the sensor chip G using the infrared absorber F-3 according to the present invention is accommodated in the sensor package 31 to constitute the thermal infrared sensor S, the incident infrared ray is determined from the size of the window portion 32 provided in the sensor package 31. The range is 2θ.
[0070]
The configuration of the infrared absorber F-3 is a two-layer structure of a metal thin film. That is, the infrared absorber F-3 is composed of first and second metal thin films 1 and 2 and an insulating film 3 interposed between the first and second metal thin films 1 and 2. The first and second metal thin films 1 and 2 are configured to be thermally coupled and not electrically contacted. As the first and second metal thin films 1 and 2, for example, Au thin films are used, and as the insulating film 3, a material that easily absorbs infrared rays, for example, silicon oxide (SiO 2) is used. It is done.
[0071]
The film thicknesses of the first and second metal thin films 1 and 2 are set so that the absorption rate in a single layer is a maximum of 0.5 (50%) (when Au is used, the film thickness is about 170 mm). ) The insulating film 3 used here is silicon oxide (SiO 2). 2 ) And the like, and the film thickness is also set to about the film thickness of the first and second metal thin films 1 and 2.
[0072]
The first metal thin film 1 and the second metal thin film 2 are arranged in this order in the infrared incident direction, and the area of the second metal thin film 2 is the area of the first metal thin film 1. It is bigger. For this reason, the direct incidence location 2A where the first metal thin film 1 does not cover the second metal thin film 2 is generated.
[0073]
In the configuration of the infrared absorber F-3, the infrared incident light includes infrared incident light a incident on the first and second metal thin films 1 and 2 and a second metal thin film as shown in FIG. 2 is incident on the first metal thin film 1 and the infrared incident light c is incident directly on the second metal thin film 2.
[0074]
In the case of the infrared incident light a, it is the same as in the first embodiment of the present invention, and when the incident infrared ray amount is 100% as shown in FIG. 3, the infrared ray that has first reached the infrared absorber F-3. 50% is absorbed by the first metal thin film 1. The remaining 50% of infrared rays a are reflected by the first metal thin film 1 as 25% as infrared reflected light (R1), and the remaining 25% are transmitted as infrared transmitted light (D1).
[0075]
The infrared transmitted light (D1) reaches the second metal thin film 2 and 12.5% is absorbed (A2). Further, about 6% of infrared rays are reflected (R2) by the second metal thin film 2, and further about 3% of infrared rays are absorbed by the first metal thin film 1.
[0076]
As described above, even when the reflection of the infrared ray by the infrared absorber F-3 is considered to be reflected once, in the two-layer structure, about 65% of the incident infrared ray is absorbed, and the infrared absorption rate in the conventional single layer is absorbed. It is about 1.3 times 50%.
[0077]
In the case of the infrared incident light b, the incident light directly enters the direct incident portion 2A of the second metal thin film 2 and is absorbed by the second metal thin film 2, and the incident infrared reflected light by the second metal thin film 2 is reflected. Among them, more infrared reflected light in a direction not perpendicular to the membrane 11 is incident on the first metal thin film 1. For example, as shown in FIG. 8, more reflected light b ′ of incident infrared rays incident on the first metal thin film 1 at the incident angle θ is incident on the first metal thin film 1.
[0078]
In the case of the infrared incident light c, the incident light directly enters the direct incident portion 2A of the second metal thin film 2 and is absorbed by the second metal thin film 2, and the reflected light of the incident infrared light C by the second metal thin film 2 Does not enter the first metal thin film 1.
[0079]
According to the above-described fourth embodiment of the present invention, the area of the second metal thin film 2 is larger than the area of the first metal thin film 1, so that the first metal thin film 1 is the second metal. A portion that does not cover the thin film 2, that is, a direct incident portion 2 A is generated, and the incident infrared ray directly incident on the direct incident portion 2 A is absorbed by the second metal thin film 2, and the incident infrared ray by the second metal thin film 2 is absorbed. Of the reflected light b ′, more reflected light in a direction not perpendicular to the membrane 11 can be incident on the first metal thin film 1. For this reason, more infrared rays can be absorbed compared with the metal thin film at the time of a single layer.
[0080]
【The invention's effect】
As described above, according to the infrared absorber according to the invention of claim 1, it is possible to insulate adjacent metal thin films and to thermally connect adjacent metal thin films. Among them, infrared light that has passed through one metal thin film can be absorbed by the other metal thin film, and infrared light reflected by the other metal thin film can be absorbed by one metal thin film. Can absorb infrared rays. As described above, it is possible to provide an infrared absorber that has a high infrared absorption rate, has high-speed response, and is easy to produce at low cost.
[0081]
Claims 1 According to the infrared absorber of the invention, it is possible to insulate adjacent metal thin films and to thermally connect adjacent metal thin films, and transmit one of the adjacent metal thin films. The infrared rays that can be absorbed by the other metal thin film and the infrared rays reflected by the other metal thin film can be absorbed by the one metal thin film, so that more infrared rays can be absorbed compared to the metal thin film in a single layer.
[0082]
Moreover, the final stage metal thin film in the multilayer structure has an infrared reflectance greater than its infrared transmittance, and the metal thin films other than the final stage metal thin film have an infrared transmittance greater than its infrared reflectance. Therefore, more infrared rays reach the final stage metal thin film, this final stage metal thin film reflects more infrared rays, and the reflected light is absorbed again by metal thin films other than the final stage metal thin film, Infrared absorption rate is improved. For example, if the infrared absorber has a two-layer structure, the infrared absorption rate is improved from 0.5 (single layer) to 0.7, and if the infrared absorber has a three-layer structure, the infrared absorption rate is 0. From 0.5 (single layer) to 0.8.
[0083]
Claims 2 According to the infrared absorber of the present invention, not only can the same effect as that of the invention of claim 1 be achieved, but the area of the other metal thin film is larger than the area of one metal thin film, In the direct incident part of the infrared rays where the metal thin film does not cover the other metal thin film, the incident infrared ray is directly absorbed by the other metal thin film, and the incident infrared light reflected by the other metal thin film is not perpendicular to the incident light. More reflected light can be incident on one metal thin film. For this reason, more infrared rays can be absorbed compared with the metal thin film at the time of a single layer.
[0084]
Claims 3 According to the thermal infrared sensor of the invention, the infrared light transmitted through one metal thin film of the infrared absorber can be absorbed by the other metal thin film, and the infrared light reflected by the other metal thin film can be absorbed by the one metal thin film. For In More infrared can be absorbed than a single layer metal thin film. Since the sensor output is improved in proportion to the increase in the absorption rate in this way, the sensitivity is improved, and noise due to fluctuations in the ambient temperature can be reduced, so that the accuracy of the sensor is improved. As described above, it is possible to provide a thermal infrared sensor using an infrared absorber that has a high infrared absorptivity, has high-speed response, and is easy to produce at low cost.
[0085]
In addition, the metal thin film at the final stage in the multilayer structure has an infrared reflectance greater than its infrared transmittance, and the metal thin film other than the metal thin film at the final stage has an infrared transmittance greater than its infrared reflectance. For this reason, more infrared rays reach the final stage metal thin film, this final stage metal thin film reflects more infrared rays, and the reflected light is again absorbed by metal thin films other than the final stage metal thin film. Infrared absorption rate is improved. For example, if the infrared absorber has a two-layer structure, the infrared absorption rate is improved from 0.5 (single layer) to 0.7, and if the infrared absorber has a three-layer structure, the infrared absorption rate is 0. From 0.5 (single layer) to 0.8.
[0086]
Claims 3 According to the thermal infrared sensor of the invention, the infrared light transmitted through one metal thin film of the infrared absorber can be absorbed by the other metal thin film, and the infrared light reflected by the other metal thin film can be absorbed by the one metal thin film. For In More infrared can be absorbed than a single layer metal thin film. Thus, since the sensor output is improved in proportion to the increase in the absorption rate, the sensitivity is improved, and noise due to fluctuations in the ambient temperature can be reduced, so that the accuracy of the sensor is improved. In addition, the thermal infrared sensor can be manufactured at low cost.
[0087]
As described above, it is possible to provide a thermal infrared sensor using an infrared absorber that has a high infrared absorptivity, has high-speed response, and is easy to produce at low cost.
[0088]
Claims 4 According to the thermal type infrared sensor of the present invention, the claim 3 In addition to having the same effect as the effect of the invention of the present invention, one metal thin film is formed on one surface of the membrane and the other metal thin film is formed on the other surface of the membrane, thereby eliminating the insulating film. Therefore, the configuration of the light receiving part of the thermal infrared sensor can be simplified.
[0089]
Claims 5 According to the thermal type infrared sensor of the present invention, the claim 3 In addition to the effects similar to the effects of the invention of the invention, when the light receiving part only needs to be on the temperature sensitive part, i.e., the hot junction part, like a thermopile sensor, a partial infrared ray absorbing part is formed on the hot junction part. By doing so, the heat capacity of the entire light receiving unit can be reduced, and as a result, the response speed is increased.
[Brief description of the drawings]
FIG. 1 is a plan view of a sensor chip of a thermal infrared sensor using an infrared absorber (Embodiment 1) according to the present invention.
FIG. 2 is a longitudinal sectional view of the sensor chip.
FIG. 3 is an operation explanatory diagram of an infrared absorber (Embodiment 1) according to the present invention.
FIG. 4 is a plan view of a sensor chip of a thermal infrared sensor using an infrared absorber (Embodiment 2) according to the present invention.
FIG. 5 is a longitudinal sectional view of the sensor chip.
6 is a plan view of a sensor chip of a thermal infrared sensor using an infrared absorber (Embodiment 3) according to the present invention. FIG.
FIG. 7 is a longitudinal sectional view of the sensor chip.
FIG. 8 is a cross-sectional view of an infrared absorber (Embodiment 4) according to the present invention.
FIG. 9 is a longitudinal sectional view of a thermal infrared sensor using the same infrared absorber.
FIG. 10 is a plan view of a sensor chip of a thermal infrared sensor using a conventional infrared absorber.
FIG. 11 is a longitudinal sectional view of the sensor chip.
FIG. 12 is a plan view of the sensor chip with the infrared absorber removed.
[Explanation of symbols]
1 First metal thin film (one metal thin film)
2 Second metal thin film (the other metal thin film)
3 Insulating film
4 Partial infrared absorption parts
10 Semiconductor substrate
11 Membrane
12 One dielectric thin film
13 Thermocouple
14 Hot junction part (temperature measuring junction) (temperature sensing part)
15 Cold junction (reference junction)
16 Terminal section
17 Terminal
18 The other dielectric thin film
19 Wire
20 Wire rod
31 Sensor package
32 windows
G Sensor chip
F Infrared absorber
F-1 Infrared absorber
F-2 Infrared absorber
F-3 Infrared absorber
S Thermal infrared sensor

Claims (5)

外部からの入射赤外線のエネルギーを熱に変換するための赤外線吸収体であって、少なくとも２つ以上の金属薄膜を有し、且つその隣り合う前記金属薄膜間に絶縁膜を介在させて多層構造にした赤外線吸収体であって、
前記多層構造における金属薄膜は、共に、単層における赤外線吸収率を最大０．５（５０％）でしかも互いに絶縁できる程度の薄膜で構成し、且つ、最終段の金属薄膜における赤外線透過率よりも赤外線反射率を大きくすると共に、前記最終段の金属薄膜以外の前記金属薄膜における赤外線反射率よりも赤外線透過率を大きくして構成したことを特徴とする赤外線吸収体。An infrared absorber for converting the energy of incident infrared radiation from the outside into heat, having at least two metal thin films, and having an insulating film interposed between the adjacent metal thin films to form a multilayer structure An infrared absorber,
The metal thin films in the multilayer structure are both thin films having a maximum infrared absorption rate of 0.5 (50%) in a single layer and can be insulated from each other, and more than the infrared transmittance of the metal thin film in the final stage. An infrared absorber characterized in that the infrared reflectance is increased and the infrared transmittance is made larger than the infrared reflectance of the metal thin film other than the metal thin film at the final stage . 外部からの入射赤外線のエネルギーを熱に変換するための赤外線吸収体であって、一方の金属薄膜と他方の金属薄膜との間に絶縁膜を介在させ、且つ赤外線の入射方向に、前記一方の金属薄膜と前記他方の金属薄膜とをこの順序で配置し、前記他方の金属薄膜の面積を前記一方の金属薄膜の面積より大きくして、前記他方の金属薄膜に赤外線の直接入射箇所を設けたことを特徴とする赤外線吸収体。An infrared absorber for converting energy of incident infrared rays from the outside into heat, wherein an insulating film is interposed between one metal thin film and the other metal thin film, The metal thin film and the other metal thin film are arranged in this order, the area of the other metal thin film is made larger than the area of the one metal thin film, and the infrared light is directly incident on the other metal thin film . An infrared absorber characterized by that. 赤外線吸収体を、少なくとも２つ以上の金属薄膜を有し且つその隣り合う前記金属薄膜間に絶縁膜を介在させて多層構造に構成し、
また、前記多層構造における金属薄膜は、共に、単層における赤外線吸収率を最大０．５（５０％）でしかも互いに絶縁できる程度の薄膜で構成し、且つ、最終段の金属薄膜における赤外線透過率よりも赤外線反射率を大きくすると共に、前記最終段の金属薄膜以外の前記金属薄膜における赤外線反射率よりも赤外線透過率を大きくし、前記赤外線吸収体を受光部にしたことを特徴とする熱型赤外線センサ。 The infrared absorber has at least two or more metal thin films, and has a multilayer structure with an insulating film interposed between the adjacent metal thin films,
The metal thin films in the multilayer structure are both thin films having a maximum infrared absorption rate of 0.5 (50%) in a single layer and can be insulated from each other, and the infrared transmittance of the final stage metal thin film. A thermal type characterized in that the infrared reflectance is made larger than that of the metal thin film other than the final stage metal thin film, and the infrared light absorber is used as a light receiving portion. Infrared sensor . 前記絶縁膜が、熱電対を誘電薄膜に封入したメンブレンである請求項３に記載の熱型赤外線センサ。 The thermal infrared sensor according to claim 3, wherein the insulating film is a membrane in which a thermocouple is enclosed in a dielectric thin film . 赤外線吸収体を、少なくとも２つ以上の金属薄膜を有し、且つその隣り合う前記金属薄膜間に絶縁膜を介在させて多層構造にし、
前記多層構造における金属薄膜が、共に、単層における赤外線吸収率を最大０．５（５０％）でしかも互いに絶縁できる程度の薄膜で構成し、且つ、最終段の金属薄膜における赤外線透過率よりも赤外線反射率を大きくすると共に、前記最終段の金属薄膜以外の前記金属薄膜における赤外線反射率よりも赤外線透過率を大きくして構成した部分赤外線吸収部で構成し、当該部分赤外線吸収部を感温部上のみに形成した受光部にしたことを特徴とする熱型赤外線センサ。The infrared absorber has at least two or more metal thin films, and has a multilayer structure by interposing an insulating film between the adjacent metal thin films,
Both of the metal thin films in the multilayer structure are composed of thin films having a maximum infrared absorption rate of 0.5 (50%) in a single layer and can be insulated from each other, and more than the infrared transmittance of the metal thin film in the final stage. In addition to increasing the infrared reflectance, the infrared radiation transmittance of the metal thin film other than the metal thin film in the final stage is set to be larger than that of the infrared radiation, and the partial infrared absorption section is temperature sensitive. A thermal infrared sensor characterized in that it is a light receiving part formed only on the part.
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