JPH07122772A - Semiconductor radiation detecting device - Google Patents
Semiconductor radiation detecting deviceInfo
- Publication number
- JPH07122772A JPH07122772A JP5270262A JP27026293A JPH07122772A JP H07122772 A JPH07122772 A JP H07122772A JP 5270262 A JP5270262 A JP 5270262A JP 27026293 A JP27026293 A JP 27026293A JP H07122772 A JPH07122772 A JP H07122772A
- Authority
- JP
- Japan
- Prior art keywords
- diffusion layer
- protective film
- substrate
- thickness
- semiconductor radiation
- 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.)
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- Measurement Of Radiation (AREA)
- Light Receiving Elements (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は放射線検出素子に係り、
特に大面積の半導体放射線検出素子に好適な放射線検出
素子に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation detecting element,
Particularly, the present invention relates to a radiation detection element suitable for a large area semiconductor radiation detection element.
【０００２】[0002]
【従来の技術】従来の半導体放射線検出素子の構造を図
２の断面図を用いて説明する。検出素子は例えばｐ型シ
リコン基板１にｎ型の拡散層２を設け、その上部にＳｉ
Ｏ2 の表面保護膜３とアルミニウム電極５の蒸着膜を設
けている。拡散層２の外周にはｐ型の拡散層をチャンネ
ルストッパー６として設けている。図２のａがシリコン
基板１の半径を、ｂがｐ−ｎ接合の拡散層２の半径を、
ｃがチャンネルストッパー６の内半径を示す。アルミニ
ウム電極５に逆バイアス７を印加すると拡散層２の下に
空乏層８が広がる。半導体検出素子の有感部はｐ−ｎ接
合に隣接して形成する空乏層８である。この空乏層内で
放射線との相互作用で生成する電子と正孔を電極に収集
し、放射線の検出信号を発生させる。一般に、半導体検
出素子の空乏層厚さは０.２〜０.３mmが限界であり、よ
り高感度な半導体検出素子を実現するためには大面積化
が不可欠となる。2. Description of the Related Art The structure of a conventional semiconductor radiation detecting element will be described with reference to the sectional view of FIG. The detection element is, for example, a p-type silicon substrate 1 on which an n-type diffusion layer 2 is provided, and Si
A surface protection film 3 of O 2 and a vapor deposition film of an aluminum electrode 5 are provided. A p-type diffusion layer is provided as a channel stopper 6 on the outer periphery of the diffusion layer 2. In FIG. 2, a is the radius of the silicon substrate 1, b is the radius of the diffusion layer 2 of the pn junction,
c indicates the inner radius of the channel stopper 6. When the reverse bias 7 is applied to the aluminum electrode 5, the depletion layer 8 spreads under the diffusion layer 2. The sensitive part of the semiconductor detection element is the depletion layer 8 formed adjacent to the pn junction. Electrons and holes generated by the interaction with radiation in this depletion layer are collected at the electrodes, and a radiation detection signal is generated. Generally, the thickness of the depletion layer of the semiconductor detection element is limited to 0.2 to 0.3 mm, and in order to realize a semiconductor detection element with higher sensitivity, it is necessary to increase the area.
【０００３】従来の半導体大面積検出素子（φ５０mm以
上）に関しては、第２７回理工学における同位元素研究
発表会要旨集（１９９０年）：４ａ−Ｉ−８，４ａ−Ｉ
−１０にアモルファスヘテロ接合型やＳＳＢ型（表面障
壁型）の記載がある。ここで、アモルファスヘテロ接合
型とは単結晶シリコン基板表面に非晶質シリコン（アモ
ルファスシリコン）を堆積させて接合を形成したもので
あり、ＳＳＢ型とは単結晶シリコン基板表面に金属を蒸
着して接合を形成したものである。これらの検出素子は
漏洩電流が大きいことや経年劣化が発生することなどが
あり、改善が望まれている。一方、プレーナ技術で製造
する拡散接合型検出素子は経年劣化がなく、均一な製品
を大量生産できるので低コスト化が図れる。拡散接合型
とは、単結晶シリコン基板表面に不純物をドープし、熱
拡散で接合を形成するものである。このため、低漏洩電
流の大面積拡散接合型検出素子の実現が強く望まれてい
る。Regarding the conventional semiconductor large-area detecting element (φ50 mm or more), abstracts of the 27th isotope research presentation in science and engineering (1990): 4a-I-8, 4a-I
-10 describes amorphous heterojunction type and SSB type (surface barrier type). Here, the amorphous heterojunction type is one in which amorphous silicon (amorphous silicon) is deposited on the surface of a single crystal silicon substrate to form a junction, and the SSB type is one in which a metal is vapor-deposited on the surface of the single crystal silicon substrate. It is what forms a bond. These detection elements have a large leakage current and may deteriorate over time, and therefore improvements are desired. On the other hand, the diffusion-bonding type detection element manufactured by the planar technology does not deteriorate with age, and uniform products can be mass-produced, so that the cost can be reduced. The diffusion bonding type is a type in which impurities are doped on the surface of a single crystal silicon substrate to form a bond by thermal diffusion. Therefore, realization of a large-area diffusion junction type detection element with low leakage current is strongly desired.
【０００４】[0004]
【発明が解決しようとする課題】一枚のウエハーから多
数の素子を切り出す小形素子の場合は、漏洩電流が大き
い不良品を種分けすることで良品を選別できる。検出素
子の漏洩電流は、空乏層の内部で発生する発生電流成分
と素子表面の漏洩電流成分とに分けられ、前者は用いる
半導体の純度（抵抗率）に、後者は素子の表面処理に依
存する。これに対して、ウエハーサイズの大きい大面積
素子は局部的にでも不良個所があれば実用品にならな
い。従って、大面積高感度素子の実現には漏洩電流の低
減が不可欠になる。In the case of a small-sized device in which a large number of devices are cut out from one wafer, a defective product having a large leakage current can be sorted into good products. The leakage current of the detection element is divided into a generated current component generated inside the depletion layer and a leakage current component of the element surface. The former depends on the purity (resistivity) of the semiconductor used, and the latter depends on the surface treatment of the element. . On the other hand, a large-area device having a large wafer size cannot be used as a practical product if there is a defective portion even locally. Therefore, reduction of leakage current is indispensable for realizing a large-area high-sensitivity element.
【０００５】本発明の目的は、高感度な大面積半導体放
射線検出素子を提供することにある。An object of the present invention is to provide a highly sensitive large area semiconductor radiation detecting element.
【０００６】[0006]
【課題を解決するための手段】上記目的を達成するため
に、第１の発明は、表面に拡散層を有するＳｉ基板と、
該拡散層の表面の一部を覆う多層保護膜と、該多層保護
膜の表面及び前記拡散層の表面を覆い該拡散層に電気的
に接する電極とを備え、前記多層保護膜は前記Ｓｉ基板
との間に発生する応力歪を緩和し、前記拡散層の厚さが
０.１μｍ 以上でμｍオーダ以下である構成としたもの
である。In order to achieve the above object, a first invention is a Si substrate having a diffusion layer on its surface,
A multilayer protective film covering a part of the surface of the diffusion layer, and an electrode covering the surface of the multilayer protective film and the surface of the diffusion layer and in electrical contact with the diffusion layer, wherein the multilayer protective film is the Si substrate. The stress strain generated between and is relaxed, and the thickness of the diffusion layer is set to 0.1 μm or more and on the order of μm or less.
【０００７】また、第２の発明は、表面に拡散層を有す
るＳｉ基板と、該拡散層の表面の一部を覆う第１の保護
膜と、該第１の保護膜の表面を覆う第２の保護膜と、該
第２の保護膜の表面及び前記拡散層の表面を覆い該拡散
層に電気的に接する電極とを備え、前記第２の保護膜は
前記Ｓｉ基板と第１の保護膜との間に発生する応力歪を
緩和し、前記拡散層の厚さが０.１μｍ 以上でμｍオー
ダ以下である構成としたものである。A second aspect of the invention is a Si substrate having a diffusion layer on the surface, a first protective film covering a part of the surface of the diffusion layer, and a second protective film covering the surface of the first protective film. And a electrode that covers the surface of the second protective film and the surface of the diffusion layer and is in electrical contact with the diffusion layer, wherein the second protective film is the Si substrate and the first protective film. The stress strain generated between and is relaxed, and the thickness of the diffusion layer is set to 0.1 μm or more and on the order of μm or less.
【０００８】また、第３の発明は、表面に拡散層を有す
るＳｉ基板と、該拡散層の表面の一部を覆う第１の保護
膜と、該第１の保護膜の表面を覆う第２の保護膜と、該
第２の保護膜の表面及び前記拡散層の表面を覆い該拡散
層に電気的に接する電極とを備え、前記第１の保護膜の
熱膨張係数は前記Ｓｉ基板より小さく、前記第２の保護
膜の熱膨張係数は前記Ｓｉ基板に比べて同等又は大き
く、前記拡散層の厚さが０.１μｍ 以上でμｍオーダ以
下である構成としたものである。A third invention is a Si substrate having a diffusion layer on its surface, a first protective film covering a part of the surface of the diffusion layer, and a second protective film covering the surface of the first protective film. And a electrode that covers the surface of the second protective film and the surface of the diffusion layer and is in electrical contact with the diffusion layer, and the thermal expansion coefficient of the first protective film is smaller than that of the Si substrate. The coefficient of thermal expansion of the second protective film is equal to or larger than that of the Si substrate, and the thickness of the diffusion layer is not less than 0.1 μm and not more than μm.
【０００９】また、第４の発明は、表面に拡散層を有す
るＳｉ基板と、該拡散層の表面の一部を覆うＳｉＯ2 膜
と、該ＳｉＯ2 膜の表面を覆うＳｉ3Ｎ4膜と、該Ｓｉ3
Ｎ4膜の表面及び前記拡散層の表面を覆い該拡散層に電
気的に接する電極とを備え、前記拡散層の厚さが０.１
μｍ 以上でμｍオーダ以下である構成としたものであ
る。[0009] A fourth aspect of the present invention is a Si substrate having a diffusion layer on the surface, and the SiO 2 film covering the portion of the surface of the diffusion layer, and the Si 3 N 4 film covering the surface of the SiO 2 film , The Si 3
An electrode that covers the surface of the N 4 film and the surface of the diffusion layer and is in electrical contact with the diffusion layer, and the thickness of the diffusion layer is 0.1.
The configuration is such that it is equal to or more than μm and is equal to or less than μm.
【００１０】[0010]
【作用】第１の発明によれば、多層保護膜がＳｉ基板と
の間に発生する応力歪を緩和することにより検出素子表
面の漏洩電流成分を低減できるので、大面積の検出素子
でも高感度化を図ることができる。また、拡散層の厚さ
を０.１μｍ 以上でμｍオーダ以下とすることにより拡
散層のｐ−ｎ接合を完全に形成できると共に、飛程の短
いα線の不感層での減衰を低減できるので、高感度で放
射線を検出することができる。According to the first aspect of the invention, the leakage current component on the surface of the detecting element can be reduced by relaxing the stress strain generated between the multilayer protective film and the Si substrate. Can be realized. Further, by setting the thickness of the diffusion layer to be 0.1 μm or more and on the order of μm or less, it is possible to completely form the pn junction of the diffusion layer and reduce the attenuation of the α-ray having a short range in the dead layer. , Can detect radiation with high sensitivity.
【００１１】また、第２の発明によれば、第２の保護膜
がＳｉ基板と第１の保護膜との間に発生する応力歪を緩
和することにより検出素子表面の漏洩電流成分を低減で
きるので、大面積の検出素子でも高感度化を図ることが
できる。また、拡散層の厚さを０.１μｍ 以上でμｍオ
ーダ以下とすることにより第１の発明と同様に高感度で
放射線を検出することができる。According to the second invention, the leakage current component on the surface of the detecting element can be reduced by relaxing the stress strain generated between the Si substrate and the first protective film by the second protective film. Therefore, high sensitivity can be achieved even with a large-area detection element. Further, by setting the thickness of the diffusion layer to be 0.1 μm or more and on the order of μm or less, radiation can be detected with high sensitivity as in the first invention.
【００１２】また、第３の発明によれば、第２の保護膜
が第１の保護膜からＳｉ基板に作用する圧縮応力を緩和
できるので、検出素子表面の漏洩電流成分を低減し、大
面積の検出素子でも高感度化を図ることができる。ま
た、拡散層の厚さを０.１μｍ以上でμｍオーダ以下と
することにより第１の発明と同様に高感度で放射線を検
出することができる。Further, according to the third invention, since the second protective film can relieve the compressive stress acting on the Si substrate from the first protective film, the leakage current component on the surface of the detecting element can be reduced and the large area can be obtained. It is possible to increase the sensitivity even with the detection element. Further, by setting the thickness of the diffusion layer to be 0.1 μm or more and on the order of μm or less, radiation can be detected with high sensitivity as in the first invention.
【００１３】また、第４の発明によれば、Ｓｉ3Ｎ4膜が
ＳｉＯ2 膜からＳｉ基板に作用する圧縮応力を緩和でき
るので、検出素子表面の漏洩電流成分を低減し、大面積
の検出素子でも高感度化を図ることができる。また、拡
散層の厚さを０.１μｍ 以上でμｍオーダ以下とするこ
とにより第１の発明と同様に高感度で放射線を検出する
ことができる。Further, according to the fourth aspect of the invention, the Si 3 N 4 film can relieve the compressive stress acting on the Si substrate from the SiO 2 film, so that the leakage current component on the surface of the detecting element can be reduced and a large area can be detected. High sensitivity can be achieved even with an element. Further, by setting the thickness of the diffusion layer to be 0.1 μm or more and on the order of μm or less, radiation can be detected with high sensitivity as in the first invention.
【００１４】次に図３を用いてＳｉ基板に働く応力につ
いて説明する。図３（ａ）はＳｉ基板１上にＳｉＯ2 膜
３を設けたときの応力を示す。ＳｉＯ2 膜の熱膨張係数
はＳｉ基板に比べて小さいので、これに基づく収縮応力
がマスクパターンエッジに作用し歪を発生させる。素子
表面の応力歪はＳｉ基板上に転位や欠陥を発生させ、こ
れが漏洩電流の原因となる。放射線の検出信号は極めて
小さいので、検出素子の漏洩電流は放射線検出の性能に
大きく影響する。図３（ｂ）はＳｉ基板１上にＳｉ3Ｎ4
膜４を設けたときの応力を示す。Ｓｉ3Ｎ4膜４の熱膨張
係数はＳｉ基板１に比べて同等かやや大きいので、Ｓｉ
基板１上には引張り応力が働く。Next, the stress acting on the Si substrate will be described with reference to FIG. FIG. 3A shows stress when the SiO 2 film 3 is provided on the Si substrate 1. Since the thermal expansion coefficient of the SiO 2 film is smaller than that of the Si substrate, the contraction stress based on the thermal expansion coefficient acts on the mask pattern edge to generate strain. The stress strain on the element surface causes dislocations and defects on the Si substrate, which causes leakage current. Since the radiation detection signal is extremely small, the leak current of the detection element greatly affects the radiation detection performance. FIG. 3B shows Si 3 N 4 on the Si substrate 1.
The stress when the film 4 is provided is shown. Since the coefficient of thermal expansion of the Si 3 N 4 film 4 is equal to or slightly larger than that of the Si substrate 1, Si
Tensile stress acts on the substrate 1.
【００１５】Ｓｉ3Ｎ4膜のこの性質を利用して図３
（ｃ）のようにＳｉ基板１上にＳｉＯ2 膜３とＳｉ3Ｎ4
膜４を二層に設けることにより、ＳｉＯ2 膜３からＳｉ
基板１に作用する圧縮応力を緩和し、表面漏洩電流成分
を低減することができる。これによって実用的な大面積
素子を実現するものである。Utilizing this property of the Si 3 N 4 film, FIG.
As shown in (c), the SiO 2 film 3 and Si 3 N 4 are formed on the Si substrate 1.
By providing the film 4 in two layers, the SiO 2 film 3 is converted into Si.
The compressive stress acting on the substrate 1 can be relaxed and the surface leakage current component can be reduced. This realizes a practical large-area device.
【００１６】[0016]
【実施例】以下、本発明の実施例を図面を用いて説明す
る。図１は本発明を大面積の半導体放射線検出素子に適
用した第１の実施例の断面を示す図である。本検出素子
は、９０mmφのｐ型シリコン基板１に厚さが０.１μｍ
以上でμｍオーダ以下のｎ型の拡散層２を設け、その上
部にＳｉＯ2 膜３とＳｉ3Ｎ4膜４の表面保護膜、更にそ
の外表面にアルミニウム電極５の蒸着膜を設ける。この
検出素子は光にも感応するため、アルミニウム電極５は
光の遮蔽も兼ねる。本検出素子は拡散接合型とし、拡散
層２の外側にはｐ型の拡散層をチャンネルストッパー６
として設ける。図１のａ，ｂ，ｃはそれぞれシリコン基
板１の半径，ｐ−ｎ接合の拡散層２の半径，チャンネル
ストッパー６の内半径を示す。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a cross section of a first embodiment in which the present invention is applied to a large area semiconductor radiation detecting element. This detection element has a thickness of 0.1 μm on a 90 mmφ p-type silicon substrate 1.
As described above, the n-type diffusion layer 2 of the order of μm or less is provided, the surface protection film of the SiO 2 film 3 and the Si 3 N 4 film 4 is provided thereon, and the vapor deposition film of the aluminum electrode 5 is provided on the outer surface thereof. Since this detection element is also sensitive to light, the aluminum electrode 5 also serves as light shield. This detection element is a diffusion junction type, and a p-type diffusion layer is provided on the outside of the diffusion layer 2 as a channel stopper 6.
It is provided as. 1A, 1B, 1C show the radius of the silicon substrate 1, the radius of the diffusion layer 2 of the pn junction, and the inner radius of the channel stopper 6, respectively.
【００１７】本検出素子のアルミニウム電極５に逆バイ
アスを端子７から印加して拡散層２の下に空乏層８を形
成する。空乏層８の厚さは印加する逆バイアスの電圧に
依存し、横方向の広がりはチャンネルストッパー６の内
径まで広がる。検出素子の放射線の有感部は空乏層８で
あり、この空乏層内で放射線との相互作用で生成する電
子と正孔をアルミニウム電極５で収集し、放射線の検出
信号を発生させる。本検出素子によれば、ＳｉＯ2 膜３
からシリコン基板１に作用する圧縮応力をＳｉ3Ｎ4膜４
で緩和することができる。従って、シリコン基板１の応
力歪に起因する表面漏洩電流成分を低減し、大面積の検
出素子でも高感度化を図ることができる。A reverse bias is applied to the aluminum electrode 5 of the present detection element from the terminal 7 to form a depletion layer 8 under the diffusion layer 2. The thickness of the depletion layer 8 depends on the reverse bias voltage applied, and the lateral expansion extends to the inner diameter of the channel stopper 6. The radiation sensitive portion of the detection element is the depletion layer 8, and electrons and holes generated by the interaction with radiation in this depletion layer are collected by the aluminum electrode 5 to generate a radiation detection signal. According to this detection element, the SiO 2 film 3
Compressive stress acting on the silicon substrate 1 from the Si 3 N 4 film 4
Can be mitigated with. Therefore, the surface leakage current component due to the stress strain of the silicon substrate 1 can be reduced, and high sensitivity can be achieved even with a large-area detection element.
【００１８】次に図４を用いて漏洩電流について説明す
る。図４は検出素子の漏洩電流成分の模式図を示す。Ｉ
ｂは検出素子の空乏層内で発生する発生電流成分、Ｉｓ
はシリコン基板の表面で発生する表面漏洩電流成分であ
る。Ｉｂは次式で表わせる。Next, the leakage current will be described with reference to FIG. FIG. 4 shows a schematic diagram of the leakage current component of the detection element. I
b is a generated current component generated in the depletion layer of the detection element, Is
Is a surface leakage current component generated on the surface of the silicon substrate. Ib can be expressed by the following equation.
【００１９】[0019]
【数１】 Ｉｂ＝ｑ・ｎｉ・Ｗ・Ｓ／(２τ) ………（数１） ここで、ｑは電子の電荷（１.６×１０-19Ｃ）、ｎｉは
真性半導体のキャリア濃度（１.５×１０10cm-3 ）、Ｗ
は空乏層の厚さ（cm）、Ｓは空乏層の表面積（cm2)、τ
は少数キャリアのライフタイム（ｓ）である。Ｗは印加
バイアスで決まり、τは用いるシリコン材料の純度で決
まる。従って、Ｉｂは検出素子の構造とその動作条件だ
けで評価できる。更に、検出素子の全漏洩電流Ｉｄは数
２の関係があるので、Ｉｄが分かればＩｓを定量でき
る。## EQU1 ## Ib = q.ni.W.S / (2.tau.) ... (Equation 1) where q is electron charge (1.6 × 10 -19 C) and ni is carrier concentration of intrinsic semiconductor. (1.5 × 10 10 cm -3 ), W
Is the thickness of the depletion layer (cm), S is the surface area of the depletion layer (cm 2 ), τ
Is the minority carrier lifetime (s). W is determined by the applied bias, and τ is determined by the purity of the silicon material used. Therefore, Ib can be evaluated only by the structure of the detecting element and its operating condition. Further, since the total leakage current Id of the detection element has a relationship of the equation 2, if Id is known, Is can be quantified.
【００２０】[0020]
【数２】 Ｉｄ＝Ｉｂ＋Ｉｓ ………（数２） 図５は表面処理と漏洩電流の関係を調べた結果を示す図
である。この関係は６mmφの小形検出素子を用いて調べ
た結果である。同図から明らかなように、従来のＳｉＯ
2 膜だけの場合に比べて、Ｓｉ3Ｎ4膜だけの場合と、Ｓ
ｉＯ2 膜とＳｉ3Ｎ4膜の二層膜構造の場合の方が低漏洩
電流となる。特に、二層膜構造の漏洩電流値は発生電流
の計算値と良く一致しており、表面電流成分を無視でき
る程度に低減できていることが分かる。この漏洩電流の
低減効果は数分の１程度であるが、これは用いた素子が
６mmφの小形素子であるためで、マスクパターンエッジ
が極端に長くなる大面積素子に対しては極めて大きな漏
洩電流の低減効果が得られる。## EQU00002 ## Id = Ib + Is (Equation 2) FIG. 5 is a diagram showing the results of examining the relationship between the surface treatment and the leakage current. This relationship is the result of investigation using a small detection element of 6 mmφ. As is clear from the figure, conventional SiO
Compared to the case of only 2 films, the case of only Si 3 N 4 film and the case of S
The leakage current is lower in the case of the two-layer film structure of the iO 2 film and the Si 3 N 4 film. In particular, the leakage current value of the two-layer film structure is in good agreement with the calculated value of the generated current, and it can be seen that the surface current component can be reduced to a negligible level. The effect of reducing this leakage current is about a few times, but this is because the element used is a small element with a diameter of 6 mm, so an extremely large leakage current is required for a large area element with an extremely long mask pattern edge. Can be obtained.
【００２１】図６は漏洩電流と有感面積の関係を調べた
結果を示す図である。同図から明らかなように、本実施
例によればウエハーサイズの大きな大面積素子（９０mm
φ）の漏洩電流を０.３μＡ 程度に抑えることができ、
従来品の１／２０以下に低減できている。半導体検出素
子は微弱信号を取扱うため、漏洩電流がμＡ程度になる
と検出性能が著しく低下する。例えば、測定のＳ／Ｎや
分解能の性能に直接影響が現れる。本実施例の大面積検
出素子の漏洩電流は数百ｎＡ以下であり、放射線の検出
性能は小形素子と同等の性能を維持できる。しかも、プ
レーナ技術で製造する拡散接合型検出素子であるため、
経年劣化がなく、均一な製品を大量生産でき低コスト化
を図ることができる。FIG. 6 is a diagram showing the results of examining the relationship between the leakage current and the sensitive area. As is clear from the figure, according to this embodiment, a large area device (90 mm) having a large wafer size is used.
φ) leakage current can be suppressed to about 0.3 μA,
It can be reduced to 1/20 or less of the conventional product. Since the semiconductor detection element handles a weak signal, the detection performance remarkably deteriorates when the leakage current becomes about μA. For example, the measurement S / N and resolution performance are directly affected. The leakage current of the large-area detection element of this embodiment is several hundreds nA or less, and the radiation detection performance can be maintained at the same level as the small-sized detection element. Moreover, because it is a diffusion junction type detection element manufactured by the planar technology,
With no deterioration over time, uniform products can be mass-produced and cost reduction can be achieved.
【００２２】次に、第１の実施例において拡散層２の厚
さを０.１μｍ 以上でμｍオーダ以下としたことによる
効果について説明する。各種の放射線（α，β，γ，中
性子線）を高感度で検出するためには、特に飛程の短い
α線（シリコン中の飛程が１０〜４０μｍ）に対して、
α線の入射窓となる不感層（アルミニウム蒸着層，表面
保護膜や拡散層）の厚さを極端に薄くする必要がある。
低エネルギーα線の飛程は１０μｍ以下となるため、不
感層の影響を無視するには不感層の厚さを１μｍ以下に
設定する必要がある。Next, the effect obtained by setting the thickness of the diffusion layer 2 in the first embodiment to 0.1 μm or more and on the order of μm or less will be described. In order to detect various radiations (α, β, γ, neutron rays) with high sensitivity, especially for α rays with a short range (range in silicon is 10 to 40 μm),
It is necessary to extremely reduce the thickness of the insensitive layer (aluminum vapor deposition layer, surface protective film or diffusion layer) that becomes the α-ray incident window.
Since the range of low-energy α-rays is 10 μm or less, it is necessary to set the thickness of the dead layer to 1 μm or less in order to ignore the influence of the dead layer.
【００２３】アルミニウム蒸着層や表面保護膜の厚さは
０.１μｍ 程度に形成する技術が既に確立されており、
技術的にも特に問題はない。一方、拡散層の厚さはでき
るだけ薄い方が良いが、拡散層が薄くなるとｐ−ｎ接合
そのものが不完全となり、漏洩電流の増大が予想され
る。このため、本発明者は拡散層厚と漏洩電流の関係を
明らかにし、α線やβ線を高感度に検出するための条件
を明らかにした。A technique for forming the aluminum vapor-deposited layer and the surface protective film to have a thickness of about 0.1 μm has already been established.
There is no technical problem. On the other hand, the thickness of the diffusion layer should be as thin as possible. However, if the diffusion layer becomes thin, the pn junction itself becomes incomplete, and leakage current is expected to increase. Therefore, the present inventor clarified the relationship between the diffusion layer thickness and the leakage current, and clarified the conditions for highly sensitive detection of α rays and β rays.
【００２４】図７に拡散層厚と漏洩電流および感度の関
係を調べた結果を示す。拡散層厚が０.１μｍ 以下にな
ると、ｐ−ｎ接合の不完全さのために漏洩電流が極端に
増大する。この関係から拡散層厚は０.１μｍ が下限と
いえる。また、拡散層厚が数μｍ以上になると不感層で
のα線の減衰が顕著になり感度の低下を招く。この厚さ
に比べアルミニウム蒸着層や表面保護膜の厚さは十分薄
いので、不感層厚が数μｍ以下の設定条件では拡散層厚
が高感度化の律速条件となる。従って、高感度な検出器
を得るための拡散層厚は０.１μｍ 〜数μｍの範囲が最
適な設計値といえる。このように入射窓を薄膜化した大
面積検出素子により高感度の放射線検出器を実現するこ
とができる。FIG. 7 shows the results of examining the relationship between the diffusion layer thickness, the leakage current and the sensitivity. When the thickness of the diffusion layer is 0.1 μm or less, the leakage current extremely increases due to the imperfection of the pn junction. From this relationship, it can be said that the lower limit of the diffusion layer thickness is 0.1 μm. Further, when the thickness of the diffusion layer is several μm or more, α rays are significantly attenuated in the insensitive layer, resulting in a decrease in sensitivity. Since the thickness of the aluminum vapor-deposited layer and the surface protective film is sufficiently smaller than this thickness, the diffusion layer thickness is the rate-determining condition for increasing the sensitivity under the setting conditions where the dead layer thickness is several μm or less. Therefore, it can be said that the optimum design value of the diffusion layer thickness in order to obtain a highly sensitive detector is in the range of 0.1 μm to several μm. As described above, a high-sensitivity radiation detector can be realized by the large-area detection element having a thin entrance window.
【００２５】次に、図８を用いて第１の実施例の信号取
出し電極の構造を説明する。図８は第１の実施例の放射
線検出素子の上面図を示す。大面積検出素子では放射線
との相互作用で生成する電荷の発生位置によって、その
収集効率が大きく異なることが予想される。このため、
本実施例ではｐ−ｎ接合の拡散層とアルミニウム電極５
のコンタクト２０を周方向の対称な４か所に設け、電荷
の収集効率を一定にする構成としている。複数のコンタ
クト２０で収集した電荷はアルミニウム電極５の蒸着面
の一点からボンディングワイヤー２１を介して逆バイア
スを印加する端子７（外部回路への信号取出し部）へ信
号を取出す。このような信号取出し電極の構造は大面積
の検出素子に不可欠な構造となる。Next, the structure of the signal extraction electrode of the first embodiment will be described with reference to FIG. FIG. 8 shows a top view of the radiation detecting element of the first embodiment. It is expected that the collection efficiency of the large-area detection element will greatly differ depending on the position where the electric charge generated by the interaction with the radiation is generated. For this reason,
In this embodiment, the diffusion layer of the pn junction and the aluminum electrode 5 are used.
The contacts 20 are provided at four symmetrical locations in the circumferential direction to make the charge collection efficiency constant. The electric charge collected by the plurality of contacts 20 is taken out from one point of the vapor deposition surface of the aluminum electrode 5 to the terminal 7 (the signal taking-out portion to the external circuit) which applies the reverse bias via the bonding wire 21. The structure of such a signal extraction electrode is an essential structure for a large-area detection element.
【００２６】図９に本発明の検出素子を放射線計測装置
に用いた第２の実施例を示す。本計測装置は、放射線検
出素子１０，カップリングコンデンサー１１，電荷増幅
器１２，線形増幅器１３，計数回路１４，演算表示器１
５などで構成される。放射線検出素子１０に逆バイアス
を端子７から印加し、放射線検出素子１０内に空乏層を
形成する。空乏層に入射した放射線は電子正孔対を生成
し、これが放射線検出信号となる。この微弱信号をカッ
プリングコンデンサー１１を介して電荷増幅器１２及び
線形増幅器１３で増幅後、計数回路１４で計数し、演算
表示器１５で放射能強度に換算して表示する。図８の構
成が各種の放射線（α，β，γ，中性子線）を計測する
計測装置の基本構成である。同図で放射線検出素子１０
は図１で説明した検出素子と同じ構成のものを用いるこ
ととし、ここでは詳細な説明は省略する。本実施例の大
面積検出素子を用いた放射線計測装置の適用範囲は、各
種の放射線モニタ（物品搬出モニタ，汚染モニタなど）
やサーベイメータなど極めて広い。更に、従来の計測装
置に比べて１桁以上の高感度化を容易に達成できる。FIG. 9 shows a second embodiment in which the detecting element of the present invention is used in a radiation measuring apparatus. This measuring device includes a radiation detecting element 10, a coupling capacitor 11, a charge amplifier 12, a linear amplifier 13, a counting circuit 14, and an operation display unit 1.
5, etc. A reverse bias is applied to the radiation detection element 10 from the terminal 7 to form a depletion layer in the radiation detection element 10. The radiation incident on the depletion layer produces electron-hole pairs, which serve as radiation detection signals. This weak signal is amplified by the charge amplifier 12 and the linear amplifier 13 via the coupling capacitor 11, counted by the counting circuit 14, and converted into radioactivity intensity by the calculation display unit 15 for display. The configuration of FIG. 8 is a basic configuration of a measuring device that measures various types of radiation (α, β, γ, neutron rays). In the figure, the radiation detection element 10
1 has the same configuration as the detection element described in FIG. 1, and detailed description thereof will be omitted here. The applicable range of the radiation measuring apparatus using the large-area detecting element of the present embodiment is various radiation monitors (such as an article carry-out monitor and a contamination monitor).
And survey meters are extremely wide. Furthermore, it is possible to easily achieve high sensitivity of one digit or more as compared with the conventional measuring device.
【００２７】尚、以上の説明はシリコン基板の表面をＳ
ｉＯ2 膜とＳｉ3Ｎ4膜の二層膜構造とすることにより漏
洩電流を低減するものであるが、他の単層表面保護膜で
素子表面の応力歪を緩和する手段や、複数の異種材料又
は同種材料の多層表面保護膜構造で応力歪を緩和する手
段を用いても同様の効果を得ることができる。In the above description, the surface of the silicon substrate is S
Although a leakage current is reduced by adopting a two-layer film structure of an iO 2 film and a Si 3 N 4 film, another single-layer surface protection film is used as a means for relaxing stress strain on the element surface, The same effect can be obtained by using a means for relaxing stress strain in a multilayer surface protective film structure of a material or a similar material.
【００２８】また、上述した検出素子は異種多層の表面
処理を行うため、その処理工程が従来の製造工程より１
工程多くなるが、低漏洩電流の大面積素子を実現できる
ことからその実用上の付加価値は大きい。Further, since the above-mentioned detection element performs surface treatment of different kinds of multilayers, the treatment process is one more than the conventional manufacturing process.
Although the number of steps increases, it is possible to realize a large-area element with low leakage current, so that its practical added value is great.
【００２９】以上、本発明を放射線検出器に適用した実
施例を説明したが、同一構造で大面積のフォトダイオー
ドとしても容易に適用可能となる。但し、フォトダイオ
ードは光を透過させる必要があるので、電極のアルミニ
ウム蒸着面を設けない構造が必要である。即ち、受光面
の一部分から電極を引出す構造とする必要がある。Although the embodiment in which the present invention is applied to a radiation detector has been described above, it can be easily applied to a large-area photodiode having the same structure. However, since the photodiode needs to transmit light, it is necessary to have a structure in which the aluminum vapor deposition surface of the electrode is not provided. That is, it is necessary to have a structure in which the electrode is drawn out from a part of the light receiving surface.
【００３０】[0030]
【発明の効果】以上説明したように、本発明によれば、
Ｓｉ基板と保護膜の間に発生する応力歪を緩和すること
により検出素子表面の漏洩電流成分を低減できると共
に、拡散層の厚さを最適な範囲に設定することにより放
射線の減衰を低減できるので、高感度な大面積半導体放
射線検出素子を実現することができる。As described above, according to the present invention,
Since the leakage current component on the surface of the detection element can be reduced by relaxing the stress strain generated between the Si substrate and the protective film, the attenuation of radiation can be reduced by setting the thickness of the diffusion layer in the optimum range. A high-sensitivity large-area semiconductor radiation detecting element can be realized.
【図１】本発明を大面積半導体放射線検出素子に適用し
た第１の実施例の断面図。FIG. 1 is a sectional view of a first embodiment in which the present invention is applied to a large area semiconductor radiation detecting element.
【図２】従来の半導体放射線検出素子の断面を示す図。FIG. 2 is a view showing a cross section of a conventional semiconductor radiation detecting element.
【図３】Ｓｉ基板に働く応力の説明図で、（ａ）はＳｉ
Ｏ2 膜のみ、（ｂ）はＳｉ3Ｎ4膜のみ、（ｃ）はＳｉＯ
2 膜とＳｉ3Ｎ4膜の二層の場合を示す図。FIG. 3 is an explanatory diagram of stress acting on a Si substrate, in which (a) is Si.
O 2 film only, (b) Si 3 N 4 film only, (c) SiO
Shows a case of two layers of 2 film and the Si 3 N 4 film.
【図４】検出素子の漏洩電流成分の模式図。FIG. 4 is a schematic diagram of a leakage current component of a detection element.
【図５】表面処理と漏洩電流の関係を示す図。FIG. 5 is a diagram showing the relationship between surface treatment and leakage current.
【図６】漏洩電流と有感面積の関係を示す図。FIG. 6 is a diagram showing a relationship between a leakage current and a sensitive area.
【図７】拡散層厚と漏洩電流および感度の関係を示す
図。FIG. 7 is a diagram showing a relationship among a diffusion layer thickness, a leakage current and sensitivity.
【図８】第１の実施例の放射線検出素子の上面図。FIG. 8 is a top view of the radiation detecting element according to the first embodiment.
【図９】本発明の検出素子を放射線計測装置に用いた第
２の実施例を示す図。FIG. 9 is a diagram showing a second embodiment in which the detection element of the present invention is used in a radiation measuring apparatus.
１…シリコン基板、２…拡散層、３…ＳｉＯ2 膜、４…
Ｓｉ3Ｎ4膜、５…アルミニウム電極、６…チャンネルス
トッパー、７…端子、８…空乏層、１０…放射線検出素
子、１１…カップリングコンデンサー、１２…電荷増幅
器、１３…線形増幅器、１４…計数回路、１５…演算表
示器、２０…コンタクト。1 ... Silicon substrate, 2 ... Diffusion layer, 3 ... SiO 2 film, 4 ...
Si 3 N 4 film, 5 ... Aluminum electrode, 6 ... Channel stopper, 7 ... Terminal, 8 ... Depletion layer, 10 ... Radiation detection element, 11 ... Coupling capacitor, 12 ... Charge amplifier, 13 ... Linear amplifier, 14 ... Counting Circuit, 15 ... Calculation display, 20 ... Contact.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 海原 明久 茨城県日立市大みか町五丁目２番１号 株 式会社日立製作所大みか工場内 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Akihisa Umihara 5-2-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Omika factory
Claims (12)
層の表面の一部を覆う多層保護膜と、該多層保護膜の表
面及び前記拡散層の表面を覆い該拡散層に電気的に接す
る電極とを備え、 前記多層保護膜は前記Ｓｉ基板との間に発生する応力歪
を緩和し、 前記拡散層の厚さが０.１μｍ 以上でμｍオーダ以下で
あることを特徴とする半導体放射線検出素子。1. A Si substrate having a diffusion layer on the surface thereof, a multilayer protective film covering a part of the surface of the diffusion layer, and an electric layer formed on the surface of the multilayer protective film and the surface of the diffusion layer. The multilayer protective film relieves stress strain generated between the multilayer substrate and the Si substrate, and the diffusion layer has a thickness of 0.1 μm or more and a μm order or less. Radiation detection element.
層の表面の一部を覆う多層保護膜と、該多層保護膜の表
面及び前記拡散層の表面を覆い該拡散層に電気的に接す
る電極とを備え、 前記多層保護膜は前記Ｓｉ基板との間に発生する応力歪
を緩和し、 前記多層保護膜と前記拡散層と前記電極の厚さの和がμ
ｍオーダ以下で、且つ、前記拡散層の厚さが０.１μｍ
以上でμｍオーダ以下であることを特徴とする半導体放
射線検出素子。2. A Si substrate having a diffusion layer on the surface thereof, a multilayer protective film covering a part of the surface of the diffusion layer, and a surface of the multilayer protective film and the surface of the diffusion layer, wherein the diffusion layer is electrically connected. The multilayer protective film relaxes stress strain generated between the Si substrate, and the total thickness of the multilayer protective film, the diffusion layer, and the electrode is μ.
m order or less, and the thickness of the diffusion layer is 0.1 μm
The semiconductor radiation detection element is characterized by being in the order of μm or less.
層の表面の一部を覆う第１の保護膜と、該第１の保護膜
の表面を覆う第２の保護膜と、該第２の保護膜の表面及
び前記拡散層の表面を覆い該拡散層に電気的に接する電
極とを備え、 前記第２の保護膜は前記Ｓｉ基板と第１の保護膜との間
に発生する応力歪を緩和し、 前記拡散層の厚さが０.１μｍ 以上でμｍオーダ以下で
あることを特徴とする半導体放射線検出素子。3. A Si substrate having a diffusion layer on the surface thereof, a first protective film covering a part of the surface of the diffusion layer, a second protective film covering a surface of the first protective film, An electrode that covers the surface of the second protective film and the surface of the diffusion layer and is in electrical contact with the diffusion layer, wherein the second protective film occurs between the Si substrate and the first protective film. A semiconductor radiation detecting element, which relaxes stress strain and has a thickness of the diffusion layer of 0.1 μm or more and on the order of μm or less.
層の表面の一部を覆う第１の保護膜と、該第１の保護膜
の表面を覆う第２の保護膜と、該第２の保護膜の表面及
び前記拡散層の表面を覆い該拡散層に電気的に接する電
極とを備え、 前記第２の保護膜は前記Ｓｉ基板と第１の保護膜との間
に発生する応力歪を緩和し、 前記第１及び第２の保護膜と前記拡散層と前記電極の厚
さの和がμｍオーダ以下で、且つ、前記拡散層の厚さが
０.１μｍ 以上でμｍオーダ以下であることを特徴とす
る半導体放射線検出素子。4. A Si substrate having a diffusion layer on the surface thereof, a first protective film covering a part of the surface of the diffusion layer, a second protective film covering a surface of the first protective film, An electrode that covers the surface of the second protective film and the surface of the diffusion layer and is in electrical contact with the diffusion layer, wherein the second protective film occurs between the Si substrate and the first protective film. The stress strain is relaxed, and the sum of the thicknesses of the first and second protective films, the diffusion layer, and the electrode is on the order of μm or less, and the thickness of the diffusion layer is 0.1 μm or more and the order of μm or less. The semiconductor radiation detecting element according to claim 1.
層の表面の一部を覆う第１の保護膜と、該第１の保護膜
の表面を覆う第２の保護膜と、該第２の保護膜の表面及
び前記拡散層の表面を覆い該拡散層に電気的に接する電
極とを備え、 前記第１の保護膜の熱膨張係数は前記Ｓｉ基板より小さ
く、前記第２の保護膜の熱膨張係数は前記Ｓｉ基板に比
べて同等又は大きく、 前記拡散層の厚さが０.１μｍ 以上でμｍオーダ以下で
あることを特徴とする半導体放射線検出素子。5. A Si substrate having a diffusion layer on its surface, a first protective film covering a part of the surface of the diffusion layer, a second protective film covering a surface of the first protective film, An electrode that covers the surface of the second protective film and the surface of the diffusion layer and is in electrical contact with the diffusion layer, wherein the thermal expansion coefficient of the first protective film is smaller than that of the Si substrate; The semiconductor radiation detecting element, wherein the thermal expansion coefficient of the film is equal to or larger than that of the Si substrate, and the thickness of the diffusion layer is 0.1 μm or more and on the order of μm or less.
導体放射線検出素子において、前記第１の保護膜はＳｉ
Ｏ2 膜であることを特徴とする半導体放射線検出素子。6. The semiconductor radiation detecting element according to claim 3, wherein the first protective film is Si.
A semiconductor radiation detecting element, which is an O 2 film.
導体放射線検出素子において、前記第２の保護膜はＳｉ
3Ｎ4膜であることを特徴とする半導体放射線検出素子。7. The semiconductor radiation detecting element according to claim 3, wherein the second protective film is Si.
A semiconductor radiation detecting element, which is a 3 N 4 film.
層の表面の一部を覆うＳｉＯ2 膜と、該ＳｉＯ2 膜の表
面を覆うＳｉ3Ｎ4膜と、該Ｓｉ3Ｎ4膜の表面及び前記拡
散層の表面を覆い該拡散層に電気的に接する電極とを備
え、 前記拡散層の厚さが０.１μｍ 以上でμｍオーダ以下で
あることを特徴とする半導体放射線検出素子。A Si substrate having a diffusion layer 8. A surface, and the SiO 2 film covering the portion of the surface of the diffusion layer, and the Si 3 N 4 film covering the surface of the SiO 2 film, the Si 3 N 4 A semiconductor radiation detecting element, comprising: an electrode that covers the surface of the film and the surface of the diffusion layer and is in electrical contact with the diffusion layer, wherein the thickness of the diffusion layer is 0.1 μm or more and μm or less. .
導体放射線検出素子において、前記電極は光を遮蔽する
ことを特徴とする半導体放射線検出素子。9. The semiconductor radiation detecting element according to claim 1, wherein the electrode shields light.
半導体放射線検出素子において、前記拡散層は熱拡散型
のｐ−ｎ接合を有することを特徴とする半導体放射線検
出素子。10. The semiconductor radiation detecting element according to claim 1, wherein the diffusion layer has a thermal diffusion type pn junction.
半導体放射線検出素子において、前記拡散層からの電極
引出しコンタクトを複数設けたことを特徴とする半導体
放射線検出素子。11. The semiconductor radiation detecting element according to claim 1, wherein a plurality of electrode lead-out contacts from the diffusion layer are provided.
の半導体放射線検出素子と、該検出素子で検出した信号
を増幅する増幅器と、該検出信号を計数する計数回路
と、該計数結果を放射能強度に換算して表示する演算表
示器とを備えたことを特徴とする放射線検出器。12. The semiconductor radiation detection element according to claim 1, an amplifier for amplifying a signal detected by the detection element, a counting circuit for counting the detection signal, and the counting result. A radiation detector, comprising: a calculation display unit for converting and displaying the radiation intensity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5270262A JPH07122772A (en) | 1993-10-28 | 1993-10-28 | Semiconductor radiation detecting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5270262A JPH07122772A (en) | 1993-10-28 | 1993-10-28 | Semiconductor radiation detecting device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07122772A true JPH07122772A (en) | 1995-05-12 |
Family
ID=17483808
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5270262A Pending JPH07122772A (en) | 1993-10-28 | 1993-10-28 | Semiconductor radiation detecting device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07122772A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019144172A (en) * | 2018-02-22 | 2019-08-29 | 株式会社東芝 | Radiation detector |
-
1993
- 1993-10-28 JP JP5270262A patent/JPH07122772A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019144172A (en) * | 2018-02-22 | 2019-08-29 | 株式会社東芝 | Radiation detector |
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