JPH02158168A - Pyroelectric infrared ray solid state image sensor and driving method therefor - Google Patents
Pyroelectric infrared ray solid state image sensor and driving method thereforInfo
- Publication number
- JPH02158168A JPH02158168A JP63313439A JP31343988A JPH02158168A JP H02158168 A JPH02158168 A JP H02158168A JP 63313439 A JP63313439 A JP 63313439A JP 31343988 A JP31343988 A JP 31343988A JP H02158168 A JPH02158168 A JP H02158168A
- Authority
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- Japan
- Prior art keywords
- thin film
- film transistor
- pyroelectric
- sensor
- electrode
- 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
- 238000000034 method Methods 0.000 title claims description 24
- 239000007787 solid Substances 0.000 title abstract description 3
- 239000010409 thin film Substances 0.000 claims abstract description 125
- 239000004065 semiconductor Substances 0.000 claims abstract description 30
- 239000012212 insulator Substances 0.000 claims abstract description 11
- 238000003384 imaging method Methods 0.000 claims description 23
- 239000003990 capacitor Substances 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 11
- 239000002184 metal Substances 0.000 claims description 10
- 230000003287 optical effect Effects 0.000 claims description 4
- 230000008859 change Effects 0.000 abstract description 11
- 238000003860 storage Methods 0.000 abstract description 11
- 230000035945 sensitivity Effects 0.000 abstract description 8
- 230000007423 decrease Effects 0.000 description 7
- 239000010408 film Substances 0.000 description 7
- 239000000758 substrate Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- 235000006693 Cassia laevigata Nutrition 0.000 description 2
- 241000522641 Senna Species 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000003321 amplification Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 229940124513 senna glycoside Drugs 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Landscapes
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は物体の温度分布を２次元の映像として表示させ
るための焦電型赤外線固体撮像装置に関するものである
。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pyroelectric infrared solid-state imaging device for displaying the temperature distribution of an object as a two-dimensional image.
従来の技術
従来、赤外線を検ｊ］３するセンサとして、赤外線を熱
に変換する焦電材料を用いたものがあり、センサの冷却
不要、感度波長の均一性、といった特徴のため広く利用
されている。このセンサの２次元化について、光学走査
、電子走査、自己走査方式のものが種々考案されている
。Conventional technology Conventionally, there is a sensor that detects infrared rays using a pyroelectric material that converts infrared rays into heat, and it has been widely used because of its characteristics such as no need for cooling the sensor and uniform sensitivity wavelength. There is. Various types of optical scanning, electronic scanning, and self-scanning systems have been devised to make this two-dimensional sensor.
しかし、単一もしくは線センサを回転または振動光学系
を用いて２次元走査を行なう光学走査方式は、装置が大
型で消費電力が大きく機械的故障寿命も短いという欠点
を有する。However, the optical scanning method in which two-dimensional scanning is performed using a rotating or vibrating optical system using a single or line sensor has the disadvantage that the device is large, consumes a large amount of power, and has a short mechanical failure life.
また、マトリックス検出器に信号を結像させて電子ビー
ムにより信号を読みだす電子ビーム方式は、一般的に感
度が低く、シかも画素数がそれほど多く形成できないた
め分解能が悪く、また前者と同様装置が大型になるなど
の欠点がある。また前者と同様に装置が大型になる等の
欠点がある。In addition, the electron beam method, in which the signal is imaged on a matrix detector and read out using an electron beam, generally has low sensitivity and also has poor resolution because it cannot form a large number of pixels. It has disadvantages such as being large. Also, like the former, there are drawbacks such as the large size of the device.
また、電荷結合素子（ＣＯＤ）のような信号の自己走査
機能を有する２次元固体電子走査部と２次元センサ部と
で構成した自己走査方式は前２方式に比べ、小型、高性
能、高信頼性といった利点が考えられ有望視されている
が、半導体素子とセンサ部との結合にまだ満足な方法が
得られていない。すなわち、例えば第２図に示すように
導電性金属支柱を用いて結線する方法（例えばインフラ
レッド フィジックス（Ｉｎｆｒａｒｅｄ、 Ｐｈｙｓ
ｉｃｓ）誌、１９巻、５１１頁、第４図に記載）では、
固体電子走査部２１の表面に形成された入力信号電極２
２と、センサ部２３の表面に形成された出力信号電極２
４との間をＩｎバンブ等の導電性金属支柱２３を用いて
結線する方法である。この方法は、結線の数が数１００
程度の場合には、信頓性も確保できるが結線の数が１０
０００個を越えると急激に技術的困難度が増大し、実用
化は難しくなる。In addition, the self-scanning method, which consists of a two-dimensional solid-state electronic scanning section with a signal self-scanning function such as a charge-coupled device (COD), and a two-dimensional sensor section is smaller, has higher performance, and is more reliable than the previous two methods. Although it is considered to be promising due to its advantages such as flexibility, a satisfactory method for bonding the semiconductor element and the sensor section has not yet been found. That is, for example, as shown in FIG.
ics), Volume 19, Page 511, Figure 4),
Input signal electrode 2 formed on the surface of solid-state electronic scanning section 21
2 and an output signal electrode 2 formed on the surface of the sensor section 23
4 using a conductive metal support 23 such as an In bump. This method requires hundreds of connections.
If the number of connections is 10, reliability can also be ensured.
If the number exceeds 1,000, the technical difficulty increases rapidly, making it difficult to put it into practical use.
また電極間隔が１００μｍ程度以下になると均一形状の
金属支柱を形成するのは非常に難しくなるので高分解能
の固体撮像装置はできない。Furthermore, if the electrode spacing is about 100 μm or less, it becomes very difficult to form metal pillars of uniform shape, and therefore a high-resolution solid-state imaging device cannot be produced.
さらに異なる従来例として、ＣＯＤを形成したシリコン
基板表面上に、絶縁膜を介して直接センサ部を形成する
構造が提案されている（例えば、特開昭６０−２１３０
５７号公報）。この方法では、センサ部として感度の良
好な焦電特性を示すＰｂＴｌ０ａ等の薄膜を用いる場合
は、薄膜形成°に６００°Ｃ程度の雰囲気中でのスパッ
タリング工程を必要とするため、シリコン基板に形成済
みのＣＯＤの特性が劣化してしまい良好な特性の固体１
’７１像装置の実現は困難である。また、大きな熱伝導
と熱容量とを有するシリコン基板とセンサ部とが近接し
ているため、センサ部の熱放散が大きくなり撮像装置の
温度分解能が低下するという欠点も有する。As a further different conventional example, a structure has been proposed in which a sensor section is directly formed on the surface of a silicon substrate on which a COD is formed, via an insulating film (for example, Japanese Patent Laid-Open No. 60-2130
Publication No. 57). In this method, when using a thin film such as PbTl0a, which exhibits pyroelectric properties with good sensitivity, as the sensor part, a sputtering process in an atmosphere of about 600°C is required to form the thin film. Solid 1 with good properties due to deterioration of the properties of COD
It is difficult to realize the '71 image device. Furthermore, since the silicon substrate, which has large heat conduction and heat capacity, is in close proximity to the sensor section, heat dissipation from the sensor section increases, resulting in a decrease in the temperature resolution of the imaging device.
発明が解決しようとする課題
本発明の目的は、小型で、感度が良く、高解像度が得ら
れ、冷却の必要のない焦電型赤外線固体撮像装置及びそ
の駆動方法を提供する事である。Problems to be Solved by the Invention An object of the present invention is to provide a pyroelectric infrared solid-state imaging device that is small, has good sensitivity, provides high resolution, and does not require cooling, and a method for driving the same.
課題を解決するための手段
本発明の焦電型赤外線固体撮像装置は、その一画素を、
一方の表面に共通電極を具備した薄膜状焦電材料の他方
の表面上に形成した第１の薄膜トランジスタのゲート電
極となる所定形状の金属層と、前記金属層及び前記薄膜
状焦電材料上に形成した絶縁体層と前記絶縁体層上に形
成した前記第１の薄膜トランジスタ及び第２の薄膜トラ
ンジスタの半導体薄膜の島と、前記各半導体薄膜の島の
表面上に形成した各々分離された所定形状の一組のソー
ス電極及びドレイン電極と、電気的に接続した前記第１
の薄膜トランジスタのソース電極と前記第２の薄膜トラ
ンジスタのドレイン電極とが前記共通電極との間に形成
する電荷積用容量とで構成したものである。Means for Solving the Problems The pyroelectric infrared solid-state imaging device of the present invention has one pixel:
A metal layer having a predetermined shape and serving as a gate electrode of a first thin film transistor formed on the other surface of a thin film pyroelectric material having a common electrode on one surface; the formed insulator layer, the semiconductor thin film islands of the first thin film transistor and the second thin film transistor formed on the insulator layer, and the separated predetermined shaped islands formed on the surfaces of the respective semiconductor thin film islands. the first electrode electrically connected to a pair of source and drain electrodes;
A charge product capacitor is formed between the source electrode of the thin film transistor and the drain electrode of the second thin film transistor and the common electrode.
作用
本発明の基本的な作用は、薄膜トランジスタの動作と同
一である。半導体薄膜と絶縁体層を介して接した焦電薄
膜がゲート電極とゲート絶縁膜との作用を行なう。すな
わち、測定対象物の温度変化ΔＴは焦電薄膜に表面電荷
の変化ΔＱを生じる。Operation The basic operation of the present invention is the same as that of a thin film transistor. A pyroelectric thin film that is in contact with a semiconductor thin film through an insulating layer functions as a gate electrode and a gate insulating film. That is, a temperature change ΔT of the object to be measured causes a change ΔQ in surface charge on the pyroelectric thin film.
この電荷の変化により焦電薄膜の表裏にはΔＶ＝ΔＱ／
Ｃ（Ｃは焦電薄膜の電気容量）の電位差が発生する。い
ま、焦電薄膜の半導体薄膜に対していない方の面、例え
ば裏面、を一定電位Ｖｇに固定しておくと、焦電薄膜の
表面、すなわち絶縁体層を介して半導体薄膜と対してい
る面の電位はＶｇ＋ΔＶとなる。この信号電圧ΔＶによ
り半導体薄膜中の絶縁体層との界面近傍の電位が変調さ
れ、すなわち、チャネル領域が形成されたり空乏層が形
成されたりして、半導体薄膜の導電率が大きく変化する
。すなわちセンサ用薄膜トランジ欠夕のソース電極とド
レイン電極との間に電流変化ΔＩが発生するわけである
。このΔＩと測定対象物の温度変化ΔＴとの関係は薄膜
トランジスタの原理を用いると次のように表わせる。Due to this change in charge, ΔV=ΔQ/
A potential difference of C (C is the capacitance of the pyroelectric thin film) is generated. Now, if the side of the pyroelectric thin film that is not facing the semiconductor thin film, such as the back side, is fixed at a constant potential Vg, then the surface of the pyroelectric thin film, that is, the side facing the semiconductor thin film through the insulator layer, will be fixed at a constant potential Vg. The potential of is Vg+ΔV. This signal voltage ΔV modulates the potential near the interface with the insulator layer in the semiconductor thin film, that is, a channel region or a depletion layer is formed, and the conductivity of the semiconductor thin film changes greatly. That is, a current change ΔI occurs between the source electrode and the drain electrode of the thin film transistor for the sensor. The relationship between this ΔI and the temperature change ΔT of the object to be measured can be expressed as follows using the principle of thin film transistors.
Ａ Ｉ／ＡＴ＝ （ΔＩ／ＡＶ）＊ （ΔＶ／ＡＱ）＊
（ΔＱ／ΔＴ）
＝Ｇｍ＊ （１／Ｃ）＊γ＊Ａ
ここで Ｇｏｄ： 薄膜トランジスタの相互フンダクタ
ンス
Ｃ：焦電薄膜の電気容量
γ ：焦電係数
Ａ ：受光面積
である。A I/AT= (ΔI/AV)* (ΔV/AQ)*
(ΔQ/ΔT) = Gm* (1/C)*γ*A where God: Mutual fundductance of thin film transistor C: Capacitance of pyroelectric thin film γ: Pyroelectric coefficient A: Light receiving area.
この式より明かなように、本発明の方法によれば、薄膜
トランジスタの増幅作用により、焦電薄膜で検知した熱
信号を薄膜トランジスタのドレイン電流変化に直接、効
率良く変換できる。所定の時間、赤外線を照射して、前
記ドレイン電流を流し続ける事により、前記ドレイン電
極と前記ソース電極との間に形成した蓄積用容量の電荷
は放出し続け、その両端の電圧は、ドレイン電流の大き
さ、すなわち、熱信号の大きさに比例して低下する。外
部駆動回路に接続しているスイッチング用薄膜トランジ
スタを開閉する事により、容品で発生しているこの電荷
蓄積用容量の両端の電圧変化を順次読みだしてゆく。As is clear from this equation, according to the method of the present invention, the thermal signal detected by the pyroelectric thin film can be directly and efficiently converted into a change in the drain current of the thin film transistor by the amplification effect of the thin film transistor. By irradiating infrared rays and continuing to flow the drain current for a predetermined period of time, the charges in the storage capacitance formed between the drain electrode and the source electrode continue to be released, and the voltage across the storage capacitance is equal to the drain current. , i.e., decreases in proportion to the magnitude of the thermal signal. By opening and closing the switching thin film transistor connected to the external drive circuit, the voltage changes across the charge storage capacitor occurring in the container are sequentially read out.
熱信号を所定時間積分して読みだすため大きな信号が得
られる事が本発明の駆動方法の大きな特徴である。また
本発明の構造では、半導体薄膜としてＣｄＳｅ等の比較
的低温で容易に良好な薄膜を形成できる材料を選ぶこと
により、最適な条件で形成した焦電薄膜上に焦電特性を
劣化させる事なく半導体薄膜を形成できる。A major feature of the driving method of the present invention is that a large signal can be obtained because the thermal signal is integrated over a predetermined period of time and read out. In addition, in the structure of the present invention, by selecting a material such as CdSe that can easily form a good thin film at a relatively low temperature as the semiconductor thin film, the pyroelectric properties of the pyroelectric thin film formed under optimal conditions are not deteriorated. A semiconductor thin film can be formed.
また従来例のように導電性金属支柱を用いていないため
、製造は極めて容易であり、かつ数１０μｍのセンサ部
ピッチにも容易に対応できるため高分解能の固体撮像装
置が可能となる。In addition, since no conductive metal support is used as in the conventional example, manufacturing is extremely easy, and a sensor part pitch of several tens of micrometers can be easily accommodated, making it possible to produce a high-resolution solid-state imaging device.
実施例
以下、本発明の一実施例を添付図面に基づいて説明する
。EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.
第１図は本発明の焦電型赤外線固体撮像装置の一実施例
をしめず断面図である。FIG. 1 is a sectional view showing one embodiment of the pyroelectric infrared solid-state imaging device of the present invention.
１は数μｍ〜数１０μｍの膜厚を存するＰｂＴ１０３や
Ｐｂ＋−ｘＬａｘＴＩ＋−ｘｚ４０ａ等の焦電材料から
なる薄膜であり赤外線センサとして作用する。この焦電
薄膜は単結晶基板を所定の厚さになるまで研磨して実施
しても良いし、ＭｇＯ等の、その表面にＰｂＴｌ０ａや
Ｐｂ＋−ｘＬａｘＴＩ＋−ｘｚ４０ａ等の焦電材料から
なる薄膜を配同性良くエピタキシアル成長できる基板上
にスパッタ法等により所定の厚さの薄膜を形成後、適当
な工程で前記基板のみを除去することによっても実現で
きる。２は前記焦電薄膜１の一方の表面上に、例えば高
周波マグネトロンスパッタ法で形成した５００ 程度の
膜厚を有する所定形状のＡ１からなるスイッチング用薄
膜トランジスタのゲート電極である。３は前記スイッチ
ング用薄膜トランジスタのゲート絶縁膜および前記焦電
薄膜の表面特性改善のために形成した絶縁体層であり例
えば高周波マグネトロンスパッタ法で形成した１０００
程度の膜厚を有する５Ｉ０２からなる。一般に薄膜ト
ランジスタにおいては、半導体薄膜とゲート絶縁体層と
の界面特性が良好であることが非常に重要である。半導
体薄膜としてＳＩやＣｄＳｅ、Ｃｃ）Ｓ等の十−族化合
物半導体を用いる場合には、５Ｉｏａは非常に良好な界
面特性を有する。４は前記ゲート電極２に対応して設け
られたスイッチング用薄膜トランジスタのチャネル領域
を形成するための半導体層である。５は、センサ用薄膜
トランジスタのチャネル領域を形成するための半導体層
である。これらの半導体層は、いずれも例えば１０００
程度の膜厚を有するＣｄＳｅ層であり、蒸着法等によ
り形成される。６゜７．８は前記半導体薄膜表面に設け
られた１０００ 程度の膜厚を有するＮｌＣｒ、Ａ１等
の金属層であり、６は前記スイッチング用薄膜トランジ
スタのドレイン電極、７は前記スイッチング用薄膜トラ
ンジスタのソース電極及び前記センサ用薄膜トランジス
タのドレイン電極、８は前記センサ用薄膜トランジスタ
のソース電極として作用する。Reference numeral 1 denotes a thin film made of a pyroelectric material such as PbT103 or Pb+-xLaxTI+-xz40a having a film thickness of several μm to several tens of μm, and acts as an infrared sensor. This pyroelectric thin film may be produced by polishing a single crystal substrate to a predetermined thickness, or by disposing a thin film made of a pyroelectric material such as MgO or PbTl0a or Pb+-xLaxTI+-xz40a on its surface. This can also be achieved by forming a thin film of a predetermined thickness by sputtering or the like on a substrate that can be epitaxially grown with good homogeneity, and then removing only the substrate in an appropriate step. Reference numeral 2 denotes a gate electrode of a switching thin film transistor made of A1 having a predetermined shape and having a film thickness of about 500 mm, which is formed on one surface of the pyroelectric thin film 1 by, for example, high frequency magnetron sputtering. 3 is an insulating layer formed to improve the surface characteristics of the gate insulating film of the switching thin film transistor and the pyroelectric thin film;
It is made of 5I02 with a film thickness of about In general, in thin film transistors, it is very important that the interface characteristics between the semiconductor thin film and the gate insulator layer be good. When a group 10 compound semiconductor such as SI, CdSe, or Cc)S is used as the semiconductor thin film, 5Ioa has very good interfacial properties. 4 is a semiconductor layer for forming a channel region of a switching thin film transistor provided corresponding to the gate electrode 2; 5 is a semiconductor layer for forming a channel region of a sensor thin film transistor. Each of these semiconductor layers has a thickness of, for example, 1000
This is a CdSe layer having a thickness of about 100 mL, and is formed by a vapor deposition method or the like. 6°7.8 is a metal layer such as NlCr or A1 having a film thickness of about 1000 nm provided on the surface of the semiconductor thin film, 6 is the drain electrode of the switching thin film transistor, and 7 is the source electrode of the switching thin film transistor. and the drain electrode of the sensor thin film transistor, 8 acts as a source electrode of the sensor thin film transistor.
さらに前記電極７は、前記焦電薄膜１の他方の表面」二
に形成した例えば２００ 程度の膜厚を有するＮｌＣｒ
からなる共通電極９との間に電荷蓄積用容量１０をも形
成している。以上の構造により１画素を構成する。撮像
装置πとして、これらの画素が複数個、所定の形状に配
列している。Further, the electrode 7 is made of NlCr having a thickness of about 200 nm, for example, formed on the other surface of the pyroelectric thin film 1.
A charge storage capacitor 10 is also formed between the common electrode 9 and the common electrode 9 . The above structure constitutes one pixel. As the imaging device π, a plurality of these pixels are arranged in a predetermined shape.
次に本発明の焦電型赤外線固体撮像装置中の１画素の動
作を詳しくのべる。第３図は本発明の焦電型赤外線固体
撮像装置の１画素の構成を、第４図はその動作を示す。Next, the operation of one pixel in the pyroelectric infrared solid-state imaging device of the present invention will be described in detail. FIG. 3 shows the configuration of one pixel of the pyroelectric infrared solid-state imaging device of the present invention, and FIG. 4 shows its operation.
チョッパーにより遮断された赤外光が間欠的に焦電薄膜
１に入射すると、チａツピング周波数が、焦電薄膜１の
熱時定数で決まる周波数よりも十分に速い場合には、焦
電薄膜１の温度変化ΔＴは時間に対してほぼ線形に増減
する。今、例えば共通電極９とセンサ用薄膜トランジス
タ１０のソース電極８との電圧をＯＶとし、スイッチン
グ用薄膜トランジスタ１１のドレイン電極の電圧を５Ｖ
とした本装置に、共通電極９側から赤外光が入射し、焦
電薄膜１の温度がΔＴだけ上昇する事により、絶縁体層
３と半導体薄膜４との界面に正の電荷がΔＱだけ誘起す
る場合を考える。この８起した正の電荷により、半導体
薄膜４の絶縁体層３と接する面の電位は共通電極９の電
位よりΔＶだけ上昇する。これは、半導体薄膜５、ソー
ス電極８、ドレイン電極７で構成したセンサ用薄膜トラ
ンジスタのゲーＩｆ位がΔＶだけ変化したことに等しい
。すなわち、第５図に示した薄膜トランジスタのゲート
電圧Ｖｇとドレイン電流■との関係を表わす図において
、動作点がＡからＢに変化したことである。これにより
ドレイン電流ＩにΔＩの変化が生じる。所定時間の間こ
のΔＩが発生し続ける事により電荷蓄積用容量１２内の
電荷は放電し、センサ用薄膜トランジスタのドレイン端
子の電圧は入射赤外光■に対応して低下する。これが本
画素のセンサ信号となる。When the infrared light blocked by the chopper intermittently enters the pyroelectric thin film 1, if the chipping frequency is sufficiently faster than the frequency determined by the thermal time constant of the pyroelectric thin film 1, the pyroelectric thin film 1 The temperature change ΔT increases or decreases almost linearly with time. Now, for example, the voltage between the common electrode 9 and the source electrode 8 of the sensor thin film transistor 10 is OV, and the voltage of the drain electrode of the switching thin film transistor 11 is 5V.
When infrared light enters this device from the common electrode 9 side, the temperature of the pyroelectric thin film 1 increases by ΔT, and a positive charge is generated at the interface between the insulating layer 3 and the semiconductor thin film 4 by ΔQ. Consider the case of induction. Due to this generated positive charge, the potential of the surface of the semiconductor thin film 4 in contact with the insulating layer 3 rises by ΔV from the potential of the common electrode 9. This is equivalent to a change in the gate If level of the sensor thin film transistor composed of the semiconductor thin film 5, the source electrode 8, and the drain electrode 7 by ΔV. That is, the operating point has changed from A to B in the diagram showing the relationship between the gate voltage Vg and drain current (2) of the thin film transistor shown in FIG. This causes a change in drain current I by ΔI. As this ΔI continues to occur for a predetermined period of time, the charges in the charge storage capacitor 12 are discharged, and the voltage at the drain terminal of the sensor thin film transistor decreases in response to the incident infrared light (2). This becomes the sensor signal of this pixel.
次に本発明の焦電型赤外線固体撮像装置の駆動方法の基
本的な考え方を述べる。マトリックス状に配列された任
意の画素のスイッチング用薄膜トランジスタのゲート電
極２に正の電圧、例えば５ｖ１ を印加し前記スイッ
チング用薄膜トランジスタをｏｎ状態にする。その後列
選択スイッチを閉じて、所定の画素中の前記電荷蓄積用
容量を前記列選択スイッチを介して接続したバイアス用
電源により充電し前記センサ用薄膜トランジスタのドレ
イン電極７の電位をＶｄに保持する。この後、前記スイ
ッチング用薄膜トランジスタのゲート電極２に負の電圧
、例えば−５Ｖ、 を印加し前記スイッチング用薄膜
トランジスタをｏｆｆ状態にすると前記電荷蓄積用容量
に保持されていた電荷は、前記センサ用薄膜トランジス
タを通じて放電し前記センサ用薄膜トランジスタのドレ
イン電極７の電位はＶｄから徐々に低下する。この時の
放電の速度は前記センサ用薄膜トランジスタのドレイン
電流の大きさに比例し、このドレイン電流の大きさは前
述の様に焦電薄膜１の温度に依存する。所定の時間経過
後、本画素を再度選択すると前記センサ用薄膜トランジ
スタのドレイン電極７の電位のＶｄからの低下分を補償
するように前記バイアス用電源より再充電する。この再
充電の開始直後の前記センサ用薄膜トランジスタのドレ
イン電極７の電位を外部回路を走査する事により順次読
みだしてゆきセンサ信号とする。あるいは、この再充電
時に流れる充電電流はドレイン電極７の電位のＶｄから
の低下分、すなわち焦電薄膜１の温度に依存するので、
各画素で発生したこの充電電流を外部回路を走査する事
により順次読みだしてゆきセンサ信号とすることも可能
である。Next, the basic concept of the driving method of the pyroelectric infrared solid-state imaging device of the present invention will be described. A positive voltage, for example 5v1, is applied to the gate electrode 2 of the switching thin film transistor of an arbitrary pixel arranged in a matrix to turn on the switching thin film transistor. Thereafter, the column selection switch is closed, and the charge storage capacitor in a predetermined pixel is charged by the bias power supply connected via the column selection switch, and the potential of the drain electrode 7 of the sensor thin film transistor is maintained at Vd. After that, when a negative voltage, for example, -5V, is applied to the gate electrode 2 of the switching thin film transistor to turn off the switching thin film transistor, the charges held in the charge storage capacitor are transferred through the sensor thin film transistor. As the discharge occurs, the potential of the drain electrode 7 of the sensor thin film transistor gradually decreases from Vd. The speed of discharge at this time is proportional to the magnitude of the drain current of the sensor thin film transistor, and the magnitude of this drain current depends on the temperature of the pyroelectric thin film 1 as described above. After a predetermined period of time has elapsed, when this pixel is selected again, it is recharged from the bias power source to compensate for the drop in potential of the drain electrode 7 of the sensor thin film transistor from Vd. Immediately after the start of this recharging, the potential of the drain electrode 7 of the sensor thin film transistor is sequentially read out by scanning an external circuit and used as a sensor signal. Alternatively, since the charging current that flows during this recharging depends on the decrease in the potential of the drain electrode 7 from Vd, that is, the temperature of the pyroelectric thin film 1,
It is also possible to sequentially read out this charging current generated in each pixel by scanning an external circuit and use it as a sensor signal.
具体的な駆動方法の一例を第６図、第７図を用いて説明
する。今、水平方向にｍ行、垂直方向にｎ列の画素から
なるマトリックスを考える。水平方向には読みだし行を
順次指定するためのＨｌ・・Ｈ・・Ｈｌのｍ段のシフト
レジスタ１３、垂直方向には読みだし列を指定するため
のＶ、・・Ｖｌ・・ｖＩ、のｎ個のスイッチＳ、がある
。これらのスイッチＳ１を介して各垂直ラインは共通の
電源Ｖｄ及び共通の出力端子ＶＯＵＴに接続される。各
画素のスイッチング用薄膜トランジスタ１１のドレイン
電極θは垂直ラインに、ゲート電極２は水平ラインに接
続している。赤外光をｏ ｎｌ ｏ ｆ ｆするチロ
ツバとセンサ信号読みだし行の選択とは周波数、位相と
も同期させる。An example of a specific driving method will be explained using FIGS. 6 and 7. Now, consider a matrix consisting of m rows of pixels in the horizontal direction and n columns in the vertical direction. In the horizontal direction, there is an m-stage shift register 13 of Hl...H...Hl for sequentially specifying readout rows, and in the vertical direction, there is a shift register 13 of V,...Vl...vI for specifying readout columns. There are n switches S. Each vertical line is connected to a common power supply Vd and a common output terminal VOUT via these switches S1. The drain electrode θ of the switching thin film transistor 11 of each pixel is connected to a vertical line, and the gate electrode 2 is connected to a horizontal line. The timing for turning on the infrared light and the selection of the sensor signal readout line are synchronized in both frequency and phase.
今、任意の１行水平ラインに注目する。赤外光の１チ目
ツピングサイクルに対して、このｉ行が暗状態から明状
態に変化した時点（Ａ時点）、明状態での時間が１／２
経過した時点（Ｂ時点）、明状態から暗状態に変化した
時点（Ｃ時点）、暗状態での時間が１／２経過した時点
（Ｂ時点）の４回、各々スイッチング用薄膜トランジス
タ１１のゲート電極に垂直方向シフトレジスタ１３の正
の電圧を所定の時間印加し、前記スイッチング用薄膜ト
ランジスタ１１をｏｎ状態にする。この。Now, pay attention to an arbitrary horizontal line. When this i row changes from a dark state to a bright state (time A), the time in the bright state is 1/2 for the first tripping cycle of infrared light.
The gate electrode of the switching thin film transistor 11 is applied four times: at the time when the time has elapsed (time B), when the bright state changes to the dark state (time C), and when 1/2 of the time in the dark state has elapsed (time B). A positive voltage of the vertical shift register 13 is applied for a predetermined period of time to turn on the switching thin film transistor 11. this.
ｎ状態の間に、１行水平ライン中の垂直方向読みだし列
を指定するためのＶ＋・・ｖｌ・・■、のｎ個のスイッ
チＳ１を所定の時間順次開閉し、ｎ個の画素のセンサ用
薄膜トランジスタ１ｏのドレイン電極に電源Ｖｄから順
次充電する。このｉ行の各画素における明状態でのセン
サ信号は前記（Ｃ時点）の時間に、１行水平ライン中の
ｎ個の垂直ライン読みだしスイッチＳ４、信号読みだし
スイッチＳ２を介して順次読みだされる。また暗状態で
のセンサ信号は前記（Ａ時点）の時間に、明状態の場合
と同様にして順次読みだされる。今、例えば（Ｃ時点）
の時間に、スイッチＨＩｌｖ、のみを閑にすると画素（
１，１）の電荷蓄積用容量にＶｄが印加され、赤外光強
度に対応して低下した前記電荷蓄積用容量の電圧を再充
電する。同時に前記信号読みだしスイッチＳ２を短時間
開状態に保持する事により低下した状態にあるセンサ用
薄膜トランジスタのドレイン電圧を、本画素の明状態の
信号として出力端子Ｖ ｏｕｔに読みだす。次にスイッ
チＨ＋ ＋ｖ２のみを閉にして画素（１，２）に同様の
動作をさせる。赤外光のチロツバが１回転する間に、行
方向のセンサ信号の読み取りのタイミングを行方向に移
動する赤外光のチロツバの速度と同期させつつｍ×ｎ個
の全画素に関して、このようなセンナ信号読み取り操作
を明状態と暗状態について各々１回づつ実施する。その
後、各画素について、その明状態と暗状態とのセンサ信
号の差を真のセンサ信号とする処理を行なう。本発明の
駆動方法ではセンナ信号の読み取りのタイミングを赤外
光のチョッパの速度と同期させているため、各画素の信
号をチョッパの回転速度で決まる時間の間積分した形で
読みだす事ができる。この信号の積分効果によりセンサ
の感度は、従来の瞬時読みだし方法に比べて大幅に改善
される。また、センサ部すなわち焦電薄膜の信号は、セ
ンサ用薄膜トランジスタによりＧｍ倍に増幅されて出力
され、更に電荷蓄積用容量により所定の時間分の信号が
積分されるため、センサ感度は従来の例に比べ数倍増加
する。またセンサ信号読みだし回路が直接、焦電薄膜と
接する構造のため、周知のホトリソグラフィ技術を用い
れば、１０μｍ程度の画素ピッチは極めて容易に実現で
き空間分解能も従来の１００μｍピッチと比べれば１０
倍程度改善される。During the n state, n switches S1 of V+...vl...■ for specifying the vertical readout column in one horizontal line are sequentially opened and closed for a predetermined time, and the n pixel sensors are The drain electrode of the thin film transistor 1o is sequentially charged from the power supply Vd. The sensor signals in the bright state of each pixel in the i row are sequentially read out at the time (time point C) through the n vertical line readout switches S4 and signal readout switches S2 in one horizontal line. be done. Further, the sensor signals in the dark state are sequentially read out at the above-mentioned time (point A) in the same manner as in the bright state. Now, for example (at point C)
If only the switch HIlv is left idle during the time, the pixel (
1, 1) is applied to the charge storage capacitor, and the voltage of the charge storage capacitor that has decreased in response to the infrared light intensity is recharged. At the same time, by holding the signal readout switch S2 open for a short time, the drain voltage of the sensor thin film transistor, which has been reduced, is read out to the output terminal V out as a bright state signal of the pixel. Next, only switch H+ +v2 is closed to cause pixels (1, 2) to perform the same operation. While the infrared light filter rotates once, the timing of reading sensor signals in the row direction is synchronized with the speed of the infrared light sensor moving in the row direction, and all m × n pixels are The senna signal reading operation is performed once each for the bright state and the dark state. Thereafter, for each pixel, a process is performed in which the difference between the sensor signals in its bright state and dark state is determined as a true sensor signal. In the driving method of the present invention, the timing of reading the senna signal is synchronized with the speed of the infrared light chopper, so the signal of each pixel can be read out in the form of an integral over the time determined by the chopper's rotation speed. . This signal integration effect significantly improves the sensitivity of the sensor compared to conventional instantaneous readout methods. In addition, the signal of the sensor section, that is, the pyroelectric thin film, is amplified by Gm times by the sensor thin film transistor and output, and the signal for a predetermined time is further integrated by the charge storage capacitor, so the sensor sensitivity remains the same as in the conventional example. It increases several times compared to the previous year. In addition, since the sensor signal readout circuit is in direct contact with the pyroelectric thin film, using well-known photolithography technology, a pixel pitch of about 10 μm can be achieved extremely easily, and the spatial resolution is also 10 μm compared to the conventional 100 μm pitch.
It will be improved by about twice as much.
また、焦電薄膜の厚さに比べ、半導体薄膜や、ソース電
極、ドレイン電極の厚さは１／１ｏ以下であり、熱容量
は非常に少ない。このため信号となる熱が焦電薄膜以外
に放散して、信号レベルが低下する事もほとんどない。Furthermore, the thickness of the semiconductor thin film, source electrode, and drain electrode is 1/10 or less compared to the thickness of the pyroelectric thin film, and the heat capacity is extremely small. Therefore, the heat that becomes the signal is dissipated to areas other than the pyroelectric thin film, and the signal level rarely decreases.
これも従来の金属柱を形成する場合に比へての、本発明
の構造による大きな利点である。This is also a major advantage of the structure of the present invention compared to forming conventional metal columns.
発明の効果
本発明の焦電型赤外線固体撮像装置及びその駆動方法に
よれば、センサ部すなわち焦電薄膜とそれに密着して形
成した薄膜トランジスタのアドレス指定機能及び信号増
幅機能により、小型で、感度が良く、高解像度が得られ
、冷却の必要のない赤外線固体撮像装置を容易に製造、
動作させることができるものであり、産業−ヒの利用価
値は高い。Effects of the Invention According to the pyroelectric infrared solid-state imaging device and its driving method of the present invention, the sensor section, that is, the pyroelectric thin film and the addressing function and signal amplification function of the thin film transistor formed in close contact with the sensor section, are compact and have high sensitivity. Easily manufacture infrared solid-state imaging devices that provide high resolution and do not require cooling.
It can be operated, and its utility value in industry is high.
第１図は本発明の焦電型赤外線固体撮像装置の構造の一
実施例を示す断面図、第２図は従来例の焦電型赤外線固
体撮像装置の構造の一実施例を示す断面図、第３図は本
発明の焦電型赤外線固体撮像装置の一画素の電気的接続
の一実施例を示す図、第４図は本発明の焦電型赤外線固
体撮像装置の一画素の動作を説明するための図、第５図
は薄膜トランジスタのゲート電圧Ｖｇとドレイン電流Ｉ
との関係を表わす図、第６図は本発明の焦電型赤外線固
体撮像装置の駆動方法の一実施例を示す図、第７図は本
発明の焦電型赤外線固体撮像装置の赤外光とセンサ信号
との関係を示す図である。
１・・・・焦電薄膜、２・・・・スイッチング用薄膜ト
ランジスタのゲート電極、３・・・・絶縁体層、４．５
・・・・半導体層、６・・・・スイッヂング用ｌ￥１メ
膜トランジスタのドレイン電極、７・・・・スイッチン
グ用薄膜トランジスタのソース電極及び前記センサ用薄
膜トランジスタのドレイン電極、８ ・・・センサ用薄
膜トランジスタのソース電極、９・・・・共通電極。
代理人の氏名 弁理士 栗野重孝 はか１名１図
第 ３ 図
２ 図
２２人力店号叱詠
第
図
第
図
第
図
粥
図FIG. 1 is a sectional view showing an example of the structure of a pyroelectric infrared solid-state imaging device of the present invention, and FIG. 2 is a sectional view showing an example of the structure of a conventional pyroelectric infrared solid-state imaging device. FIG. 3 is a diagram showing an example of the electrical connection of one pixel of the pyroelectric infrared solid-state imaging device of the present invention, and FIG. 4 explains the operation of one pixel of the pyroelectric infrared solid-state imaging device of the present invention. Figure 5 shows the gate voltage Vg and drain current I of the thin film transistor.
FIG. 6 is a diagram showing an embodiment of the method for driving the pyroelectric infrared solid-state imaging device of the present invention, and FIG. 7 is a diagram showing the relationship between the pyroelectric infrared solid-state imaging device of the present invention and It is a figure showing the relationship between and a sensor signal. DESCRIPTION OF SYMBOLS 1... Pyroelectric thin film, 2... Gate electrode of switching thin film transistor, 3... Insulator layer, 4.5
... Semiconductor layer, 6... Drain electrode of l\1 membrane transistor for switching, 7... Source electrode of switching thin film transistor and drain electrode of the sensor thin film transistor, 8... For sensor Source electrode of thin film transistor, 9... common electrode. Name of agent: Patent attorney Shigetaka Kurino
Claims (3)
の他方の表面上に形成した第１の薄膜トランジスタのゲ
ート電極となる所定形状の金属層と、前記金属層及び前
記薄膜状焦電材料上に形成した絶縁体層と、前記絶縁体
層上に形成した前記第１の薄膜トランジスタ及び第２の
薄膜トランジスタの半導体薄膜の島と、前記各半導体薄
膜の島の表面上に形成した各々分離された所定形状の一
組のソース電極及びドレイン電極と、電気的に接続した
前記第１の薄膜トランジスタのソース電極と前記第２の
薄膜トランジスタのドレイン電極とが前記共通電極との
間に形成する電荷積用容量とで一画素を構成したことを
特徴とする焦電型赤外線固体撮像装置。(1) A metal layer having a predetermined shape and serving as a gate electrode of a first thin film transistor formed on the other surface of a thin film pyroelectric material having a common electrode on one surface, and the metal layer and the thin film pyroelectric material. an insulator layer formed on the material, semiconductor thin film islands of the first thin film transistor and second thin film transistor formed on the insulator layer, and isolated semiconductor thin film islands formed on the surface of each of the semiconductor thin film islands. A charge product formed between a pair of source and drain electrodes having a predetermined shape and the common electrode and the electrically connected source electrode of the first thin film transistor and the drain electrode of the second thin film transistor. A pyroelectric infrared solid-state imaging device characterized in that one pixel is composed of a capacitor and a capacitor.
の他方の表面上に形成した第１の薄膜トランジスタのゲ
ート電極となる所定形状の金属層と、前記金属層及び前
記薄膜状焦電材料上に形成した絶縁体層と、前記絶縁体
層上に形成した前記第１の薄膜トランジスタ及び第２の
薄膜トランジスタの半導体薄膜の島と、前記各半導体薄
膜の島の表面上に形成した各々分離された所定形状の一
組のソース電極及びドレイン電極と、電気的に接続した
前記第１の薄膜トランジスタのソース電極と前記第２の
薄膜トランジスタのドレイン電極とが前記共通電極との
間に形成する電荷積用容量とで一画素を構成し、前記画
素を一平面上にｍ行×ｎ列の２次元的に配列し、同一の
行にある各画素中の前記第１の薄膜トランジスタのゲー
ト電極を共通の行ラインに接続し、ｍ本の前記行ライン
を各々行選択用シフトレジスタに接続し、同一の列にあ
る各画素中の前記第１の薄膜トランジスタのドレイン電
極を共通の列ラインに接続し、ｎ本の前記列ラインを列
選択用スイッチを介して出力ラインに接続した２次元焦
電型赤外線固体撮像装置の駆動方法であって、行方向の
センサ信号の読み取りのタイミングを行方向に移動する
赤外光のチョッパの速度と同期させつつ前記行選択用シ
フトレジスタ及び列選択用スイッチを順次開閉すること
により、ｍ×ｎ個の全画素のセンサ信号を所定の時間内
に順次前記出力ラインに読みだすことを特徴とする焦電
型赤外線固体撮像装置の駆動方法。(2) A metal layer having a predetermined shape and serving as a gate electrode of a first thin film transistor formed on the other surface of the thin film pyroelectric material having a common electrode on one surface, and the metal layer and the thin film pyroelectric material. an insulator layer formed on the material, semiconductor thin film islands of the first thin film transistor and second thin film transistor formed on the insulator layer, and isolated semiconductor thin film islands formed on the surface of each of the semiconductor thin film islands. A charge product formed between a pair of source and drain electrodes having a predetermined shape and the common electrode and the electrically connected source electrode of the first thin film transistor and the drain electrode of the second thin film transistor. The pixels are two-dimensionally arranged in m rows x n columns on one plane, and the gate electrodes of the first thin film transistors in each pixel in the same row are arranged in a common row. line, the m row lines are each connected to a row selection shift register, the drain electrodes of the first thin film transistors in each pixel in the same column are connected to a common column line, and the m row lines are connected to a row selection shift register. A method for driving a two-dimensional pyroelectric infrared solid-state imaging device in which the column line of the device is connected to an output line via a column selection switch, the method comprising: moving the timing of reading a sensor signal in the row direction in the infrared direction; By sequentially opening and closing the row selection shift register and column selection switch in synchronization with the speed of the optical chopper, sensor signals of all m×n pixels are sequentially read out to the output line within a predetermined time. A method for driving a pyroelectric infrared solid-state imaging device, characterized in that:
各々２回の前記第１の薄膜トランジスタのドレイン電極
への充電及び１回のセンサ信号の読み取りをおこない、
明状態でのセンサ信号と暗状態でのセンサ信号との差分
を真のセンサ信号とすることを特徴とする請求項２に記
載の焦電型赤外線固体撮像装置の駆動方法。(3) For each pixel, during one bright state and one dark state,
charging the drain electrode of the first thin film transistor twice and reading the sensor signal once;
3. The method of driving a pyroelectric infrared solid-state imaging device according to claim 2, wherein a difference between a sensor signal in a bright state and a sensor signal in a dark state is used as the true sensor signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63313439A JPH02158168A (en) | 1988-12-12 | 1988-12-12 | Pyroelectric infrared ray solid state image sensor and driving method therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63313439A JPH02158168A (en) | 1988-12-12 | 1988-12-12 | Pyroelectric infrared ray solid state image sensor and driving method therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02158168A true JPH02158168A (en) | 1990-06-18 |
Family
ID=18041311
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63313439A Pending JPH02158168A (en) | 1988-12-12 | 1988-12-12 | Pyroelectric infrared ray solid state image sensor and driving method therefor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02158168A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1093063C (en) * | 1996-05-15 | 2002-10-23 | 本田技研工业株式会社 | Installation structure of auxiliary foot-rest for small base motorcycle |
| JP2011174919A (en) * | 2010-01-26 | 2011-09-08 | Seiko Epson Corp | Detection circuit for thermal sensor, thermal sensor device, and electronic device |
-
1988
- 1988-12-12 JP JP63313439A patent/JPH02158168A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1093063C (en) * | 1996-05-15 | 2002-10-23 | 本田技研工业株式会社 | Installation structure of auxiliary foot-rest for small base motorcycle |
| JP2011174919A (en) * | 2010-01-26 | 2011-09-08 | Seiko Epson Corp | Detection circuit for thermal sensor, thermal sensor device, and electronic device |
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