JPH0749997B2 - Pyroelectric infrared array element - Google Patents
Pyroelectric infrared array elementInfo
- Publication number
- JPH0749997B2 JPH0749997B2 JP61272488A JP27248886A JPH0749997B2 JP H0749997 B2 JPH0749997 B2 JP H0749997B2 JP 61272488 A JP61272488 A JP 61272488A JP 27248886 A JP27248886 A JP 27248886A JP H0749997 B2 JPH0749997 B2 JP H0749997B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- pyroelectric
- array element
- infrared array
- pyroelectric infrared
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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Description
【発明の詳細な説明】 産業上の利用分野 本発明は焦電薄膜を用いた焦電型赤外線アレイ素子に関
するものである。TECHNICAL FIELD The present invention relates to a pyroelectric infrared array device using a pyroelectric thin film.
従来の技術 焦電型赤外線検出器は熱型の赤外線検出器で、常温動作
が可能で、感度の波長依存性が小さく、熱型検出器のな
かでは高感度である。2. Description of the Related Art Pyroelectric infrared detectors are thermal infrared detectors that are capable of operating at room temperature, have a small wavelength dependence of sensitivity, and have high sensitivity among thermal detectors.
焦電型検出器に使用されている材料にはTGS系・LiTaO3
系等の単結晶、PbTiO3系・Pbx Zr1-x TiO3系のセラミッ
ク、PVF2系等の有機膜等がある。The material used for the pyroelectric detector is TGS-based LiTaO 3
There is a single crystal such as a system, a PbTiO 3 system / Pb x Zr 1-x TiO 3 system ceramic, a PVF 2 system organic film, and the like.
PbTiO3は焦電材料の性能指数であるFv（＝γ／εCv）及
び が高い。ここでγは焦電係数、εは誘電率、Cvは体積比
熱、ｄは厚さである。また、PbTiO3は焦電係数の温度変
化が小さく、キュリー点が十分高い等の特長をもってい
る。焦電型検出器にはPbTiO3磁器が用いられる場合が多
い。磁器は多結晶であり、結晶軸の配列に方向性は無
く、したがって自発分極Psもランダムに配列している。
焦電材料は自発分極Psの変化を出力として取り出すた
め、Psが一方向に揃っているとき、最大出力が得られ
る。そこで、磁器には高電界を印加してPsの向きを揃え
る分極処理が必要である。PbTiO 3 is the figure of merit of pyroelectric materials Fv (= γ / εCv) and Is high. Here, γ is the pyroelectric coefficient, ε is the dielectric constant, Cv is the volume specific heat, and d is the thickness. In addition, PbTiO 3 has the characteristics that the change in pyroelectric coefficient with temperature is small and the Curie point is sufficiently high. PbTiO 3 porcelain is often used for the pyroelectric detector. The porcelain is a polycrystal, and the crystal axes are not directional, so that the spontaneous polarization Ps is also randomly arranged.
Since the pyroelectric material takes out the change in the spontaneous polarization Ps as an output, the maximum output is obtained when Ps is aligned in one direction. Therefore, it is necessary to apply a high electric field to the porcelain so that the Ps direction is aligned.
また、Ｃ軸配向したPbTiO3薄膜の配向軸方向に発生する
焦電気を利用した場合、Ｃ軸方向の誘電率が低下し、焦
電係数が増大するので、PbTiO3磁器の約３倍のFvを示す
高感度焦電材料を実現できることが、第30回応用物理学
関係連合講演予稿集7P−ｚ−２に報告されている。Also, when using a pyroelectric generated in the orientation direction of the PbTiO 3 films oriented C axis, the dielectric constant is reduced in the C-axis direction, the pyroelectric coefficient increases, about three times the Fv of PbTiO 3 ceramic It has been reported in the 30th Joint Lecture on Applied Physics Proceedings, 7P-z-2, that a highly sensitive pyroelectric material that exhibits
発明が解決しようとする問題点 焦電材料の厚さが薄くなるほど、雑音が小さくなり、検
出能:D＊は増大する。PbTiO3磁器でアレイを構成する場
合、磁器の薄膜化には限界があり、厚さを薄くしてＤ＊
を向上することは限界がある。また、各エレメント間の
クロストークが大きくなり空間分解能が低下する。その
ため各エレメントを分離することが必要となる。面積を
小さくすると電気容量が小さくなるため、外部からの静
電容量、浮遊容量の点から小形化も困難となる。Problems to be Solved by the Invention As the thickness of the pyroelectric material becomes thinner, the noise becomes smaller and the detectability: D * increases. When making an array with PbTiO 3 porcelain, there is a limit to how thin the porcelain can be made.
There is a limit to improving. In addition, the crosstalk between each element increases and the spatial resolution decreases. Therefore, it is necessary to separate each element. If the area is made smaller, the electric capacity becomes smaller, so it is difficult to make it smaller in terms of external electrostatic capacity and stray capacity.
さらに、焦電材料に分極処理を施すとき次のような問題
点が生じる。Further, the following problems occur when the pyroelectric material is polarized.
（１）分極処理により絶縁破壊が生じる場合がある。(1) Dielectric breakdown may occur due to polarization treatment.
（２）高密度に配列している高分解能アレイ素子では、
それらを均一に分極することが困難である。(2) In the high resolution array elements arranged in high density,
It is difficult to polarize them uniformly.
（３）半導体デバイス上に焦電薄膜を形成した集積化デ
バイスでは、分極処理そのものが不可能な場合がある。(3) In an integrated device in which a pyroelectric thin film is formed on a semiconductor device, polarization treatment itself may not be possible.
問題点を解決するための手段 化学式がPb1-x Lax Ti1-0.75x O3で組成範囲が０＜ｘ＜
0.15であり、分極軸の75％以上が一方向に配向している
焦電薄膜と、膜方向の熱伝導が焦電薄膜による熱伝導よ
り小さくなるように薄膜化された電極を用いる。Means for Solving Problems The chemical formula is Pb 1-x La x Ti 1-0.75x O 3 and the composition range is 0 <x <
It is 0.15, and a pyroelectric thin film in which 75% or more of the polarization axis is oriented in one direction and an electrode thinned so that heat conduction in the film direction is smaller than that of the pyroelectric thin film are used.
作用 上記のような焦電薄膜を用いた赤外線アレイ素子におい
ては、各エレメントを分離しなくてもクロストークが小
さいため工程数を低減できる。またPsが既に揃った自然
分極を有する焦電薄膜を用いることにより、分極処理を
おこなう必要が無く、歩留まり良く、高性能の焦電型赤
外線アレイ素子が実現できる。Action In the infrared array element using the pyroelectric thin film as described above, the number of steps can be reduced because the crosstalk is small even if the elements are not separated. Further, by using a pyroelectric thin film having natural polarization with Ps already aligned, it is not necessary to perform polarization treatment, and a high-performance pyroelectric infrared array element with good yield can be realized.
実施例 第１図は本発明の焦電型赤外線アレイ素子の構造を示す
図である。EXAMPLE FIG. 1 is a diagram showing the structure of a pyroelectric infrared array element of the present invention.
（100）でへき開し鏡面研摩したMgO単結晶基板１上に、
電極薄膜２として膜厚0.1〜0.4μｍのPt薄膜をスパッタ
リングにより形成した。スパッタガスはAr−O2混合ガス
である。ついで、焦電薄膜３としてPb1-x Lax Ti
1-0.75x O3（PLT）を４μｍ成長させた。方法は高周波
マグネトロンスパッタ法で、ArとO2の混合ガスを用い、
スパッタリングターゲットは ｛（１−Ｙ）Pb1-x Lax Ti1-0.75x O3＋Y PbO｝ の粉末である。表１にスパッタリング条件を示す。On the MgO single crystal substrate 1 cleaved with (100) and mirror-polished,
As the electrode thin film 2, a Pt thin film having a film thickness of 0.1 to 0.4 μm was formed by sputtering. The sputtering gas is an Ar-O 2 mixed gas. Then, Pb 1-x La x Ti as the pyroelectric thin film 3
1-0.75x O 3 (PLT) was grown to 4 μm. The method is a high frequency magnetron sputtering method, using a mixed gas of Ar and O 2 ,
The sputtering target is a powder of {(1-Y) Pb 1-x La x Ti 1-0.75x O 3 + Y PbO}. Table 1 shows the sputtering conditions.
次に、この焦電薄膜３上にNiCrからなる複数の受光電極
薄膜４を蒸着した後、取り出し電極５を作製した。さら
に、焦電薄膜３の下部におけるMgO基板１を熱濃燐酸に
よりエッチングし開口部６を設けた。Next, a plurality of light-receiving electrode thin films 4 made of NiCr were vapor-deposited on the pyroelectric thin film 3, and then extraction electrodes 5 were produced. Further, the MgO substrate 1 below the pyroelectric thin film 3 was etched with hot concentrated phosphoric acid to form an opening 6.
第２図及び第３図に電極薄膜２の膜厚が変化したとき
の、クロストークと感度の変化の様子を示す。クロスト
ークと感度は電極薄膜２の膜厚に強く影響を受け、膜厚
の減少とともにクロストークは減少し感度は増大する。
電極薄膜２の膜厚が0.1μｍのとき、電極薄膜２が各エ
レメント毎に分離している試料と比較してクロストーク
の値は２割程度大きかった。したがって上記膜厚のと
き、電極薄膜２による熱伝導が焦電薄膜３による熱伝導
より小さいと考えられる。 2 and 3 show changes in crosstalk and sensitivity when the film thickness of the electrode thin film 2 changes. Crosstalk and sensitivity are strongly influenced by the film thickness of the electrode thin film 2, and as the film thickness decreases, the crosstalk decreases and the sensitivity increases.
When the film thickness of the electrode thin film 2 was 0.1 μm, the value of crosstalk was about 20% larger than that of the sample in which the electrode thin film 2 was separated for each element. Therefore, at the above film thickness, it is considered that the heat conduction by the electrode thin film 2 is smaller than that by the pyroelectric thin film 3.
PLT焦電薄膜が分極軸の75％以上が一方向に配向してい
るとき、焦電係数：γは５×10-8C／cm2Kとなり、この
値は200℃で100kV/cm印加して分極処理を行ったPbTiO3
セラミクス（γ＝1.8x10-8C／cm2K）とくらべかなり大
きい。配向率90％の場合焦電係数は6.8x10-8C／cm2Kで
ある。また、分極処理後の値と比べ殆ど変わらないばか
りでなく、配向率が小さい場合の分極後の値より大き
い。誘電率は、配向率90％の場合、セラミクスとほぼ同
等の値で約200である。When 75% or more of the polarization axis of the PLT pyroelectric thin film is oriented in one direction, the pyroelectric coefficient: γ is 5 × 10 -8 C / cm 2 K, and this value is 100 kV / cm at 200 ° C. Polarized PbTiO 3
It is considerably larger than the ceramics (γ = 1.8x10 -8 C / cm 2 K). When the orientation rate is 90%, the pyroelectric coefficient is 6.8 × 10 -8 C / cm 2 K. In addition, it is almost the same as the value after the polarization treatment, and is larger than the value after the polarization when the orientation ratio is small. When the orientation rate is 90%, the dielectric constant is about 200, which is almost the same value as that of ceramics.
本実施例に用いたPLT膜厚では、薄膜作製時に十分にｃ
軸に配向しておれば分極処理を行わなくても自発分極が
揃っており、特に配向率75％以上の薄膜でその効果が大
きい。また、焦電材料としての性能指数であるFv（＝γ
／εCv）の値も大きくなる。200℃で10分間100kV/cm印
加して分極処理を行ったPbTiO3セラミクスの値と比較し
て、PLT薄膜は３倍強の値を示した。The PLT film thickness used in this example is sufficiently c
If the film is oriented along the axis, spontaneous polarization will be uniform even if polarization treatment is not performed, and the effect is particularly large in a thin film with an orientation rate of 75% or more. In addition, Fv (= γ which is a figure of merit as a pyroelectric material
The value of / εCv) also increases. Compared with the value of PbTiO 3 ceramics which was subjected to polarization treatment by applying 100 kV / cm for 10 minutes at 200 ° C., the PLT thin film showed a value more than 3 times.
以上述べたように、本発明による焦電薄膜を用いた焦電
型赤外線アレイ素子は、焦電薄膜を各エレメント毎に分
離することなく優れた特性を実現することができる。As described above, the pyroelectric infrared array element using the pyroelectric thin film according to the present invention can realize excellent characteristics without separating the pyroelectric thin film for each element.
発明の効果 本発明による焦電型赤外線アレイ素子は、焦電薄膜を各
エレメント毎に分離しない構成であるので、工程数が減
り、位置合わせの問題が解消し、高密度アレイが可能と
なる。また分極処理が不要であり高性能指数である焦電
薄膜を用いるので、特性も優れていて、歩留まりも大幅
に減少するので実用的にきわめて有効である。EFFECTS OF THE INVENTION Since the pyroelectric infrared array element according to the present invention has a configuration in which the pyroelectric thin film is not separated for each element, the number of steps is reduced, the problem of alignment is solved, and a high-density array is possible. Further, since a pyroelectric thin film which does not require polarization treatment and has a high performance index is used, the characteristics are excellent and the yield is greatly reduced, which is extremely effective in practice.
【図面の簡単な説明】 第１図は本発明の一実施例における焦電型赤外線アレイ
素子の構造を示す斜視図、第２図及び第３図は各々、本
発明の一実施例に於ける電極薄膜の膜厚と、クロストー
ク及び感度との関係を示すグラフである。 １……MgO基板、２……電極薄膜、３……焦電薄膜、４
……受光電極薄膜、６……開口部。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the structure of a pyroelectric infrared array element according to an embodiment of the present invention, and FIGS. 2 and 3 are each an embodiment of the present invention. It is a graph which shows the film thickness of an electrode thin film, and the relationship between crosstalk and sensitivity. 1 ... MgO substrate, 2 ... electrode thin film, 3 ... pyroelectric thin film, 4
...... Light receiving electrode thin film, 6 …… Aperture.
Claims (4)
極薄膜と、前記第１の電極薄膜上に作られた化学式がPb
1-x Lax Ti1-0.75x O3で組成範囲が０＜Ｘ＜0.15であり
〈001〉方向に配向している焦電薄膜と、前記焦電薄膜
上に形成された複数の分離した受光電極薄膜とを有する
ことを特徴とする焦電型赤外線アレイ素子。1. A substrate, a first electrode thin film formed on the substrate, and a chemical formula formed on the first electrode thin film is Pb.
1-x La x Ti 1-0.75x O 3 having a composition range of 0 <X <0.15 and oriented in the <001> direction, and a plurality of separated pyroelectric thin films formed on the pyroelectric thin film. A pyroelectric infrared array element comprising a light receiving electrode thin film.
膜による熱伝導より小さくなるように前記第１の電極薄
膜の膜厚を薄くしたことを特徴とする特許請求の範囲第
１項記載の焦電型赤外線アレイ素子。2. The thin film of the first electrode thin film is thinned so that the heat conduction in the film direction of the first electrode thin film is smaller than that of the pyroelectric thin film. The pyroelectric infrared array element as described in 1 above.
り除いたことを特徴とする特許請求の範囲第１項記載の
焦電型赤外線アレイ素子。3. The pyroelectric infrared array element according to claim 1, wherein a part of the substrate which is in contact with the first electrode thin film is removed.
用いたことを特徴とする特許請求の範囲第２項記載の焦
電型赤外線アレイ素子。4. A pyroelectric infrared array element according to claim 2, wherein the (100) -oriented platinum is used for the first electrode thin film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61272488A JPH0749997B2 (en) | 1986-11-14 | 1986-11-14 | Pyroelectric infrared array element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61272488A JPH0749997B2 (en) | 1986-11-14 | 1986-11-14 | Pyroelectric infrared array element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63124923A JPS63124923A (en) | 1988-05-28 |
| JPH0749997B2 true JPH0749997B2 (en) | 1995-05-31 |
Family
ID=17514619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61272488A Expired - Fee Related JPH0749997B2 (en) | 1986-11-14 | 1986-11-14 | Pyroelectric infrared array element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0749997B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR950001303A (en) * | 1993-06-22 | 1995-01-03 | 이헌조 | Thin film infrared sensor structure and manufacturing method |
| US5446284A (en) * | 1994-01-25 | 1995-08-29 | Loral Infrared & Imaging Systems, Inc. | Monolithic detector array apparatus |
-
1986
- 1986-11-14 JP JP61272488A patent/JPH0749997B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63124923A (en) | 1988-05-28 |
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