JPS6369272A - Pyroelectric thin film - Google Patents
Pyroelectric thin filmInfo
- Publication number
- JPS6369272A JPS6369272A JP61213256A JP21325686A JPS6369272A JP S6369272 A JPS6369272 A JP S6369272A JP 61213256 A JP61213256 A JP 61213256A JP 21325686 A JP21325686 A JP 21325686A JP S6369272 A JPS6369272 A JP S6369272A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- pyroelectric
- pyroelectric thin
- sputtering
- polarization
- 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.)
- Pending
Links
- 239000010409 thin film Substances 0.000 title claims abstract description 35
- 230000010287 polarization Effects 0.000 claims abstract description 17
- 239000000203 mixture Substances 0.000 claims abstract description 7
- 239000000126 substance Substances 0.000 claims abstract description 3
- 238000004544 sputter deposition Methods 0.000 abstract description 7
- 239000000758 substrate Substances 0.000 abstract description 5
- 239000013078 crystal Substances 0.000 abstract description 4
- 238000001755 magnetron sputter deposition Methods 0.000 abstract description 2
- 238000000034 method Methods 0.000 abstract description 2
- 229910018487 Ni—Cr Inorganic materials 0.000 abstract 1
- 239000000919 ceramic Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 229910052573 porcelain Inorganic materials 0.000 description 4
- 230000002269 spontaneous effect Effects 0.000 description 4
- 239000010408 film Substances 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 241000287828 Gallus gallus Species 0.000 description 1
- 229910003781 PbTiO3 Inorganic materials 0.000 description 1
- -1 TaO3 type Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000005616 pyroelectricity Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000005477 sputtering target Methods 0.000 description 1
Landscapes
- Physical Vapour Deposition (AREA)
- Ceramic Capacitors (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は焦電型赤外線検出素子に用いられる焦電薄膜に
関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pyroelectric thin film used in a pyroelectric infrared detection element.
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。Conventional technology Pyroelectric infrared detectors are thermal infrared detectors that can operate at room temperature, have low sensitivity dependence on wavelength, and are highly sensitive among thermal detectors.
焦電型検出器に使用されている材料にはTGS系・Li
TaO3系等の単結晶、P b T i Os系・Pb
xZr+−xTiO2系のセラミック、PvF2系等の
有機膜等がある。Materials used in pyroelectric detectors include TGS and Li.
Single crystal such as TaO3 type, Pb TiOs type/Pb
Examples include xZr+-xTiO2-based ceramics and PvF2-based organic films.
P b T i O3は焦電材料の性能指数であるFv
(−7/gCv)及びFm (−y/CvJεd t
anδ)が高い。P b T i O3 is Fv which is the figure of merit of pyroelectric material
(-7/gCv) and Fm (-y/CvJεd t
anδ) is high.
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、PbTiOsは焦電係数の温度
変化が小さく、キュリ一点が十分高い等の特長をもって
いる。焦電型検出器にはP b T i O3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<、シたがって自発分極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。Here, γ is the pyroelectric coefficient, ε is the permittivity, Cv is the volumetric specific heat,
d is the thickness. Furthermore, PbTiOs has features such as a small change in pyroelectric coefficient with temperature and a sufficiently high Curie point. Pb Ti O3 porcelain is often used for pyroelectric detectors. Porcelain is polycrystalline, and there is no directionality in the arrangement of crystal axes, so the spontaneous polarization Ps is also arranged randomly. Pyroelectric materials extract changes in spontaneous polarization Ps as output, so when Ps is aligned in one direction,
Maximum output is obtained. Therefore, it is necessary to polarize the ceramic by applying a high electric field to align the directions of Ps.
また、C軸配向したP b T i O3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、PbTiC)+
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。Furthermore, when using pyroelectricity generated in the orientation axis direction of a C-axis oriented PbTiC)+ thin film, the dielectric constant in the C-axis direction decreases and the pyroelectric coefficient increases.
Proceedings of the 30th Applied Physics Association Lecture Proceedings 7P-
It is reported in z-2.
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京は増大する。P b T i Os磁器で構
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DIを向上することは限度がある。Problems to be Solved by the Invention As the thickness of the pyroelectric material becomes thinner, the noise becomes smaller and the detectability: Dky increases. In the case of using P b T i Os porcelain, there is a limit to how thin the porcelain film can be, and there is a limit to how DI can be improved by reducing the thickness.
また、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。Also, as the area becomes smaller, the capacitance becomes smaller, so
Miniaturization is also difficult due to external capacitance and stray capacitance.
また、上記のPbTi03薄膜も誘電率が低いので、容
量の点から高密度化が困難となる。Furthermore, since the above-mentioned PbTi03 thin film also has a low dielectric constant, it is difficult to increase the density from the viewpoint of capacity.
さらに、焦電薄膜に分極処理を施すとき次のような問題
点が生じる。Furthermore, the following problems occur when polarizing a pyroelectric thin film.
(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)高分解能アレイ素子の様に多(の微小素子が高密
度に配列しているものでは、それらを均一に分極するこ
とが困難である。(2) In a high-resolution array element in which a large number of microelements are arranged at 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 itself may not be possible in some cases.
問題点を解決するための手段
化学式が Pbl−、cLax Tit−o、7sx
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を構成する。Means to solve the problem The chemical formula is Pbl-, cLax Tit-o, 7sx
A pyroelectric thin film is composed of O3 and has a composition range of 0<X<0.15 and is oriented in the <001> direction.
作用
上記のような焦電薄膜においては、Psが既に揃った自
然分極が得られ、分極処、理をおこなう必要が無く、歩
留まり良く、高性能の焦電薄膜が実現できる。Function: In the above-mentioned pyroelectric thin film, natural polarization in which Ps is already aligned can be obtained, and there is no need for polarization treatment or treatment, and a high-performance pyroelectric thin film with good yield can be realized.
実施例
(100)でへき開し鏡面研摩したMgO単結晶を基板
とし、下部電極として膜厚0.2μm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−02
混合ガスである。ついで、焦電薄膜として、Pbl−x
La)(Tit−o、tsx Os (PLT)を1〜
4μm成長させた。方法は高周波マグネトロンスパッタ
法で、A rと02の混合ガスを用い、スパッタリング
ターゲットは
((1−Y)Pbl−x Lax Tit−o、7sx
03 +Y PbO1の粉末である。表1にスパッ
タリング条件を示す。Using the MgO single crystal cleaved and mirror polished in Example (100) as a substrate, a 0.2 μm thick PT thin film was formed as a lower electrode by sputtering. Sputtering gas is Ar-02
It is a mixed gas. Then, as a pyroelectric thin film, Pbl-x
La) (Tit-o, tsx Os (PLT) from 1 to
It was grown to 4 μm. The method is high-frequency magnetron sputtering, using a mixed gas of Ar and 02, and the sputtering target is ((1-Y)Pbl-x Lax Tit-o, 7sx
03 +Y PbO1 powder. Table 1 shows the sputtering conditions.
次に、この薄膜上に上部電極としてNi−Cr電極を蒸
着し、焦電薄膜素子を作製した。さらに、焦電薄膜の下
部における基板には開口部を設けた。Next, a Ni--Cr electrode was deposited as an upper electrode on this thin film to produce a pyroelectric thin film element. Furthermore, an opening was provided in the substrate below the pyroelectric thin film.
第1図に代表的な薄膜のX線回折パターンを示す。ペロ
ブスカイト構造の(001)と(100)反射、及びそ
の高次の反射のみ観察される。また(00f)反射の強
度が(100)のそれと比べて著しく大きいのでC軸配
向膜であることがわかる。C軸配向率αを次の式で定義
する。Figure 1 shows the X-ray diffraction pattern of a typical thin film. Only the (001) and (100) reflections of the perovskite structure and their higher-order reflections are observed. Furthermore, since the intensity of the (00f) reflection is significantly larger than that of (100), it can be seen that it is a C-axis oriented film. The C-axis orientation rate α is defined by the following equation.
α−1101)/(l<oo+)+Iuoo)1ここで
I<oo+)、および1(1003はそれぞれ(001
)と(100)反射の回折強度を表す。α-1101)/(l<oo+)+Iuoo)1 where I<oo+) and 1(1003 are (001
) and (100) represent the diffraction intensity of reflection.
C軸配向率αはスパッタリング条件である成膜速度・ス
パッタリングガス・ガス圧・基板温度・ターゲットによ
り変化することが明確となった。It has become clear that the C-axis orientation ratio α changes depending on the sputtering conditions, such as the deposition rate, sputtering gas, gas pressure, substrate temperature, and target.
第2図に組成XとC軸配向率αの平均値との関係を示す
。FIG. 2 shows the relationship between the composition X and the average value of the C-axis orientation ratio α.
C軸配向率αはXが増えるとともに低下し、X=O,1
5ではαはかなり低下する。The C-axis orientation rate α decreases as X increases, and X=O,1
5, α drops considerably.
第3図にC軸配向率をパラメータにしてXに対するPL
T薄膜の焦電係数:γの変化、第4図に誘電率:εの変
化を示す。αが等しいとき、焦電係数:γ及び誘電率:
εはXとともに増大する。Figure 3 shows the PL with respect to X using the C-axis orientation rate as a parameter.
Figure 4 shows the change in the pyroelectric coefficient: γ of the T thin film, and the change in the dielectric constant: ε. When α is equal, pyroelectric coefficient: γ and permittivity:
ε increases with X.
第3図及び第4図のデータから焦電材料の性能指数であ
るFm(−γ/Cv Jεd tanδ)を計算して第
5図に示した。Flはα771”17L 「ときXとと
もに増え、X−0,1以上で飽和する。第2図で示した
ようにXによるαの変化を考慮するとX−0,1でFm
は最大となる。The figure of merit Fm (-γ/Cv Jεd tan δ) of the pyroelectric material was calculated from the data in FIGS. 3 and 4 and is shown in FIG. Fl increases with time X and becomes saturated above X-0,1.As shown in Figure 2, considering the change in α due to X, Fm at X-0,1
is maximum.
第6図にC軸配向率に対するPLT薄膜の焦電係数;γ
の変化、第7図に誘電率:εの変化を示す。焦電係数は
自発分極Psの配向に比例して大きくなる。焦電係数は
配向率の増加とともに太き(なり、誘電率は小さくなる
。第6図及び第7図は分極処理(200℃で100kV
/cjlo分印加)を行なった場合の結果についても示
しである。配向率が小さい場合、分極処理前後で焦電係
数及び誘電率の値は大きく変化する。配向率が75零に
なると焦電係数は5.0x10’C/cjKとなり、こ
の値は200℃で100kV/cm印加して分極処理を
行ったPbTi0oセラミクス(γ−1.8xlo−8
C/cjK)とくらべかなり大きい。配向率90零の場
合焦電係数は6.8xlO−1i1C/c+jK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90zの場合、セラミクスはぼ同等の値
で約200である。Figure 6 shows the pyroelectric coefficient of the PLT thin film with respect to the C-axis orientation rate;
Figure 7 shows the change in dielectric constant: ε. The pyroelectric coefficient increases in proportion to the orientation of the spontaneous polarization Ps. The pyroelectric coefficient becomes thicker as the orientation rate increases, and the dielectric constant becomes smaller.
The results are also shown in the case where the voltage is applied (application of /cjlo). When the orientation rate is small, the values of the pyroelectric coefficient and permittivity change significantly before and after the polarization treatment. When the orientation rate becomes 75 zero, the pyroelectric coefficient becomes 5.0x10'C/cjK, and this value is the same as that of PbTi0o ceramics (γ-1.8xlo-8
C/cjK) is considerably larger. When the orientation rate is 90 and zero, the pyroelectric coefficient is 6.8xlO-1i1C/c+jK. Moreover, not only is it almost the same as the value after polarization treatment, but it is also larger than the value after polarization when the orientation rate is small. When the orientation rate is 90z, the dielectric constant of ceramics is approximately the same as that of about 200.
以上述べたとおり、PLT薄膜では、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
果が大きいことが明らかになった。As mentioned above, in a PLT thin film, if the thin film is sufficiently oriented along the C-axis during production, the spontaneous polarization will be uniform even without polarization treatment, and this effect is particularly large for thin films with an orientation rate of 75% or more. It became clear.
本実施例で作製した焦電薄膜を赤外線センサとして利用
する場合、焦電材料としての性能指数であるFv(−γ
/εCv)の値も太き(なる。200℃で10分間10
0kV/am印加して分極処理を行ったpbTiOaセ
ラミクスの値と比較して、PLT薄膜は3倍強の値を示
す。つまり、本発明による焦電薄膜を用いると、全く分
極処理を行わな(でも優れた特性の赤外線センサが作製
されることがわかる。When using the pyroelectric thin film produced in this example as an infrared sensor, Fv (-γ
/εCv) also becomes thicker.
Compared to the value of pbTiOa ceramics subjected to polarization treatment by applying 0 kV/am, the PLT thin film exhibits a value more than three times as large. In other words, it can be seen that by using the pyroelectric thin film according to the present invention, an infrared sensor with excellent characteristics can be produced without any polarization treatment.
発明の効果
本発明による焦電薄膜は、分極処理が不要であり、また
特性も優れていて、作製も容易であるがら、実用的にき
わめて有効である。Effects of the Invention The pyroelectric thin film according to the present invention does not require polarization treatment, has excellent properties, is easy to produce, and is extremely effective in practice.
第1図は発明の一実施例における焦電薄膜のX線回折パ
ターンを示す図、第2図〜第5図は各々、本発明の一実
施例に於ける焦電薄膜の組成Xと、C軸配向率、焦電係
数、誘電率及び性能指数:F層との関係を示すグラフ、
第6図はC軸配向率と焦電係数の関係を示すグラフ、第
7図はC軸配向率と誘電率の関係を示すグラフである。
代理人の氏名 弁理士 中尾敏男 ほか12第 3 図
O占乃 o、t θ15
1 しり戸9ミ −レニ(
配回率:べ 8
洒S差× ゝ
第4図
o o、os o、to o、t
s机八へX
第5図
0 0.05 0./Q θ15狙八
X
第6図
θ、6 σ、8
1.OC軸酉芭同牢;べ
第7図
O16θ、81O
C車臼酉己181率 医FIG. 1 is a diagram showing the X-ray diffraction pattern of a pyroelectric thin film in an embodiment of the invention, and FIGS. 2 to 5 show the composition X and C of the pyroelectric thin film in an embodiment of the invention, respectively. Axial orientation ratio, pyroelectric coefficient, dielectric constant, and figure of merit: graph showing the relationship with the F layer,
FIG. 6 is a graph showing the relationship between the C-axis orientation rate and the pyroelectric coefficient, and FIG. 7 is a graph showing the relationship between the C-axis orientation rate and the dielectric constant. Name of agent Patent attorney Toshio Nakao et al. ,t
s To machine 8X Figure 5 0 0.05 0. /Q θ15 aim eight X Figure 6 θ, 6 σ, 8
1. OC axis rooster joint prison; 7th figure O16θ, 81OC C wheel miller 181 rate medical
Claims (3)
_0_._7_5_xO_3で組成範囲が0<X<0.
15であり<001>方向に配向していることを特徴と
する焦電薄膜。(1) The chemical formula is Pb_1_-_xLa_xTi_1_-
_0_. _7_5_xO_3 and the composition range is 0<X<0.
15 and is oriented in the <001> direction.
を特徴とする特許請求の範囲第1項記載の焦電薄膜。(2) The pyroelectric thin film according to claim 1, wherein 75% or more of the polarization axes are oriented in one direction.
求の範囲第1項記載の焦電薄膜。(3) The pyroelectric thin film according to claim 1, characterized in that the composition is X-0.1.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP61213256A JPS6369272A (en) | 1986-09-10 | 1986-09-10 | Pyroelectric thin film |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP61213256A JPS6369272A (en) | 1986-09-10 | 1986-09-10 | Pyroelectric thin film |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS6369272A true JPS6369272A (en) | 1988-03-29 |
Family
ID=16636084
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP61213256A Pending JPS6369272A (en) | 1986-09-10 | 1986-09-10 | Pyroelectric thin film |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6369272A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5717157A (en) * | 1993-12-01 | 1998-02-10 | Matsushita Electric Industrial Co., Ltd. | Ferroelectric thin film and method of manufacturing the same |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57188460A (en) * | 1981-05-12 | 1982-11-19 | Matsushita Electric Ind Co Ltd | Titanium perovskite compound sintered body and manufacture |
JPS59138004A (en) * | 1983-01-27 | 1984-08-08 | 松下電器産業株式会社 | Ferrodielectric thin film |
-
1986
- 1986-09-10 JP JP61213256A patent/JPS6369272A/en active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57188460A (en) * | 1981-05-12 | 1982-11-19 | Matsushita Electric Ind Co Ltd | Titanium perovskite compound sintered body and manufacture |
JPS59138004A (en) * | 1983-01-27 | 1984-08-08 | 松下電器産業株式会社 | Ferrodielectric thin film |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5717157A (en) * | 1993-12-01 | 1998-02-10 | Matsushita Electric Industrial Co., Ltd. | Ferroelectric thin film and method of manufacturing the same |
US5989395A (en) * | 1993-12-01 | 1999-11-23 | Matsushita Electric Industrial Co., Ltd. | Ferroelectric thin film and method of manufacturing the same |
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