JP6120041B2 - Radiation detection element and radiation detector - Google Patents
Radiation detection element and radiation detector Download PDFInfo
- Publication number
- JP6120041B2 JP6120041B2 JP2012017611A JP2012017611A JP6120041B2 JP 6120041 B2 JP6120041 B2 JP 6120041B2 JP 2012017611 A JP2012017611 A JP 2012017611A JP 2012017611 A JP2012017611 A JP 2012017611A JP 6120041 B2 JP6120041 B2 JP 6120041B2
- Authority
- JP
- Japan
- Prior art keywords
- substrate
- detection element
- radiation detection
- radiation
- metal 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.)
- Active
Links
- 230000005855 radiation Effects 0.000 title claims description 109
- 238000001514 detection method Methods 0.000 title claims description 73
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 113
- 239000000758 substrate Substances 0.000 claims description 91
- 229910052751 metal Inorganic materials 0.000 claims description 31
- 239000002184 metal Substances 0.000 claims description 31
- 229910052697 platinum Inorganic materials 0.000 claims description 29
- 239000013078 crystal Substances 0.000 claims description 21
- 229910052760 oxygen Inorganic materials 0.000 claims description 15
- 150000001875 compounds Chemical class 0.000 claims description 13
- 239000004065 semiconductor Substances 0.000 claims description 13
- 229910052714 tellurium Inorganic materials 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 10
- 229910052793 cadmium Inorganic materials 0.000 claims description 10
- 239000001301 oxygen Substances 0.000 claims description 10
- MARUHZGHZWCEQU-UHFFFAOYSA-N 5-phenyl-2h-tetrazole Chemical compound C1=CC=CC=C1C1=NNN=N1 MARUHZGHZWCEQU-UHFFFAOYSA-N 0.000 claims description 9
- 239000000956 alloy Substances 0.000 claims description 9
- 229910045601 alloy Inorganic materials 0.000 claims description 9
- 239000010931 gold Substances 0.000 claims description 9
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 8
- 229910052737 gold Inorganic materials 0.000 claims description 8
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 claims description 8
- CEKJAYFBQARQNG-UHFFFAOYSA-N cadmium zinc Chemical compound [Zn].[Cd] CEKJAYFBQARQNG-UHFFFAOYSA-N 0.000 claims description 6
- 230000007423 decrease Effects 0.000 claims description 6
- 229910052738 indium Inorganic materials 0.000 claims description 6
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims description 6
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 3
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052801 chlorine Inorganic materials 0.000 claims description 3
- 239000000460 chlorine Substances 0.000 claims description 3
- 229910052733 gallium Inorganic materials 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- 239000011701 zinc Substances 0.000 claims description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 2
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims 1
- 239000010410 layer Substances 0.000 description 65
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 32
- 238000007747 plating Methods 0.000 description 26
- 238000000034 method Methods 0.000 description 22
- 239000000203 mixture Substances 0.000 description 17
- 239000000243 solution Substances 0.000 description 17
- 239000002344 surface layer Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 14
- 238000007772 electroless plating Methods 0.000 description 13
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 12
- 238000007517 polishing process Methods 0.000 description 11
- 239000010408 film Substances 0.000 description 10
- 238000004544 sputter deposition Methods 0.000 description 8
- 238000001228 spectrum Methods 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 6
- 238000005520 cutting process Methods 0.000 description 6
- 238000000151 deposition Methods 0.000 description 6
- 239000002390 adhesive tape Substances 0.000 description 5
- 230000008021 deposition Effects 0.000 description 5
- 229920002120 photoresistant polymer Polymers 0.000 description 5
- 238000006467 substitution reaction Methods 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 150000004687 hexahydrates Chemical class 0.000 description 2
- 229940046892 lead acetate Drugs 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- MODGUXHMLLXODK-UHFFFAOYSA-N [Br].CO Chemical compound [Br].CO MODGUXHMLLXODK-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000007261 regionalization Effects 0.000 description 1
- 238000000682 scanning probe acoustic microscopy Methods 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000004506 ultrasonic cleaning Methods 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
Description
本発明は、化合物半導体で形成された基板と基板の表面に形成された金属電極とを備える放射線検出素子、この放射線検出素子を備える放射線検出器、およびこの放射線検出素子を製造する方法に関する。 The present invention relates to a radiation detection element including a substrate formed of a compound semiconductor and a metal electrode formed on the surface of the substrate, a radiation detector including the radiation detection element, and a method of manufacturing the radiation detection element.
テルル化カドミウム（ＣｄＴｅ）やテルル化亜鉛カドミウム（ＣｄＺｎＴｅ）などを含む化合物半導体の用途の１つに放射線検出器がある。放射線検出器は、化合物半導体結晶で形成された板状の基板の両面に金属電極を形成した放射線検出素子に回路を接続することで構成され、放射線検出素子が放射線を受けた際に放出する電子量を回路で電流に変換して増幅することにより、放射線を検出することができるようになっている。
ＣｄＴｅやＣｄＺｎＴｅはＳｉやＧｅに比べてバンドギャップエネルギーが大きいため、常温で使用でき、かつ高い精度で放射線を検出することができる。また、ＣｄＴｅやＣｄＺｎＴｅは光電子増倍管を用いるシンチレータと異なり、放射線を直接電流に変換するので、放射線検出器を小型化することができる。
One application of compound semiconductors that include cadmium telluride (CdTe), zinc cadmium telluride (CdZnTe), and the like is a radiation detector. A radiation detector is configured by connecting a circuit to a radiation detection element in which metal electrodes are formed on both sides of a plate-like substrate made of a compound semiconductor crystal, and emits electrons when the radiation detection element receives radiation. Radiation can be detected by converting the amount into current by a circuit and amplifying it.
Since CdTe and CdZnTe have a larger band gap energy than Si and Ge, they can be used at room temperature and can detect radiation with high accuracy. Further, unlike a scintillator using a photomultiplier tube, CdTe or CdZnTe converts radiation directly into a current, so that the radiation detector can be miniaturized.
基板の表面に回路と接続するための金属電極を形成する方法としては、従来、真空蒸着やめっき等が知られているが、最近では、塩化金酸や塩化白金酸を含むめっき液に基板を浸漬し、基板表面の所定箇所に金あるいは白金を析出させることにより金電極または白金電極を形成する無電解めっきがよく用いられている（特許文献１〜７参照）。 As a method for forming a metal electrode for connecting to a circuit on the surface of a substrate, vacuum deposition or plating has been conventionally known. Recently, a substrate is applied to a plating solution containing chloroauric acid or chloroplatinic acid. Electroless plating that forms a gold electrode or a platinum electrode by immersing and depositing gold or platinum at a predetermined location on the substrate surface is often used (see Patent Documents 1 to 7).
しかしながら、従来の無電解めっきにより形成された金電極あるいは白金電極は、基板との密着性が充分ではないことが多く、基板から剥がれ易くなっていた。このため、製造時の歩留まりが低下してしまうという問題や、放射線検出器としての寿命が短くなってしまうという問題を招いていた。 However, gold electrodes or platinum electrodes formed by conventional electroless plating often have insufficient adhesion to the substrate, and have been easily peeled off from the substrate. For this reason, the problem that the yield at the time of manufacture falls and the problem that the lifetime as a radiation detector becomes short were invited.
本発明は、上記課題を解決するためになされたもので、化合物半導体で形成された基板と、基板表面に形成された金属電極と、を備えた放射線検出素子において、製造時の歩留まりを高めるとともに、その寿命を長くすることを目的とする。 The present invention has been made to solve the above problems, and in a radiation detection element including a substrate formed of a compound semiconductor and a metal electrode formed on the surface of the substrate, the manufacturing yield is improved. The purpose is to extend its life.
請求項１に記載の発明は、
テルル化カドミウムまたはテルル化亜鉛カドミウムを含む化合物半導体結晶で形成された基板と、前記基板の表面に白金または金の単体、もしくは白金または金を含む合金で形成された金属電極と、を備えた放射線検出素子において、
前記基板の表層であってその表面に前記金属電極が形成される部位には、テルルの酸化物を含む中間層が形成されており、
前記中間層には、
テルルおよび酸素が、それぞれ前記基板の深さ方向に向かうに従って増加した後に減少するよう分布するとともに、
カドミウムが、テルルおよび酸素が最も多くなる深さ近傍から、前記基板の深さ方向に向かうに従って増加し始めるよう分布していることを特徴としている。
The invention described in claim 1
Radiation comprising: a substrate formed of a compound semiconductor crystal containing cadmium telluride or zinc cadmium telluride; and a metal electrode formed of platinum or gold alone or an alloy containing platinum or gold on the surface of the substrate. In the detection element,
An intermediate layer containing tellurium oxide is formed on the surface of the substrate where the metal electrode is formed on the surface.
In the intermediate layer,
Tellurium and oxygen are distributed so as to decrease after increasing toward the depth of the substrate, respectively,
Cadmium is distributed so as to start increasing in the depth direction of the substrate from the vicinity of the depth where tellurium and oxygen are the largest.
請求項２に記載の発明は、請求項１に記載の放射線検出素子において、前記中間層の平均膜厚は、０．１μｍ以上０．７μｍ以下であることを特徴としている。 According to a second aspect of the present invention, in the radiation detection element according to the first aspect, an average film thickness of the intermediate layer is not less than 0.1 μm and not more than 0.7 μm.
請求項３に記載の発明は、請求項１または２に記載の放射線検出素子において、前記基板がテルル化亜鉛カドミウムを含む化合物半導体である場合の前記基板の亜鉛の含有量は、２原子％以上９原子％以下であることを特徴としている。 The invention according to claim 3 is the radiation detection element according to claim 1 or 2, wherein the zinc content of the substrate when the substrate is a compound semiconductor containing zinc cadmium telluride is 2 atomic% or more. It is characterized by 9 atomic% or less.
請求項４に記載の発明は、請求項１から３の何れか一項に記載の放射線検出素子において、前記基板の前記金属電極が形成される主面は、結晶面（１１１）、（１１０）または（１００）であることを特徴としている。 According to a fourth aspect of the present invention, in the radiation detecting element according to any one of the first to third aspects, the main surface of the substrate on which the metal electrode is formed is a crystal plane (111), (110) Or (100).
請求項５に記載の発明は、請求項１から４の何れか一項に記載の放射線検出素子において、前記基板を構成する化合物半導体には、不純物として塩素またはインジウムが添加されていることを特徴としている。 The invention according to claim 5 is the radiation detection element according to any one of claims 1 to 4, wherein chlorine or indium is added as an impurity to the compound semiconductor constituting the substrate. It is said.
請求項６に記載の発明は、請求項１から５の何れか一項に記載の放射線検出素子において、前記中間層は、全体に亘ってテルルに対する酸素の原子数比（Ｏ／Ｔｅ）が０．６超になっていることを特徴としている。 According to a sixth aspect of the present invention, in the radiation detection element according to any one of the first to fifth aspects, the intermediate layer has an oxygen atomic ratio (O / Te) to tellurium of 0 throughout. It has become .6 than is characterized in Rukoto.
請求項７に記載の発明は、請求項１から６の何れか一項に記載の放射線検出素子において、前記金属電極は、白金単体で形成された第１層と、白金とは異なる金属で形成されるとともに前記第１層に積層された第２層と、からなることを特徴としている。 The invention according to claim 7 is the radiation detection element according to any one of claims 1 to 6, wherein the metal electrode is formed of a first layer formed of platinum alone and a metal different from platinum. And a second layer laminated on the first layer.
請求項８に記載の発明は、請求項１から６の何れか一項に記載の放射線検出素子において、前記金属電極は、白金を含む合金で形成されていることを特徴としている。 According to an eighth aspect of the present invention, in the radiation detecting element according to any one of the first to sixth aspects, the metal electrode is formed of an alloy containing platinum.
請求項９に記載の発明は、請求項１から８の何れか一項に記載の放射線検出素子において、前記基板の表裏両主面に、白金単体または白金を含む合金で前記金属電極が形成されていることを特徴としている。 According to a ninth aspect of the present invention, in the radiation detection element according to any one of the first to eighth aspects, the metal electrode is formed of platinum alone or an alloy containing platinum on both front and back main surfaces of the substrate. It is characterized by having.
請求項１０に記載の発明は、請求項１から８の何れか一項に記載の放射線検出素子において、前記基板の一方の主面には、白金単体または白金を含む合金で前記金属電極が形成され、他方の主面には、アルミニウム、ガリウムまたはインジウムで前記金属電極が形成されていることを特徴としている。 A tenth aspect of the present invention is the radiation detection element according to any one of the first to eighth aspects, wherein the metal electrode is formed of platinum alone or an alloy containing platinum on one main surface of the substrate. The metal electrode is formed of aluminum, gallium or indium on the other main surface.
請求項１１に記載の発明は、請求項１から１０の何れか一項に記載の放射線検出素子において、前記金属電極の平均膜厚は、１０ｎｍ以上１００ｎｍ以下であることを特徴としている。 The invention according to claim 11 is the radiation detection element according to any one of claims 1 to 10, wherein an average film thickness of the metal electrode is 10 nm or more and 100 nm or less.
請求項１２に記載の発明は、放射線検出器において、請求項１から１１の何れか一項に記載の放射線検出素子を備えることを特徴としている。 The invention according to claim 12, in the radiation detector, and further comprising a radiation detection element according to any one of claims 1 to 11.
本発明によれば、化合物半導体で形成された基板と、基板表面に形成された金属電極と、を備えた放射線検出素子において、製造時の歩留まりを向上させることができるとともに、その寿命を長くすることができる。 According to the onset bright, in the radiation detecting element comprising: a substrate formed of a reduction compound semiconductor, and a metal electrode formed on the substrate surface, and it is possible to improve the yield in manufacturing, its lifetime Can be lengthened .
＜実施形態＞
以下、図面を参照して、本発明の実施形態について詳細に説明する。
<Embodiment>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
〔放射線検出器の構成〕
まず、本実施形態の放射線検出器の概略構成について説明する。
図１に示すように、本実施形態の放射線検出器１は、放射線検出素子２、コンデンサ３、増幅器４、マルチチャンネルアナライザ（ＭＣＡ）５等で構成されている。放射線検出素子２は、その一方の電極（共通電極７）がグランドに接続（接地）され、他方の電極（ピクセル電極８）が負電位に接続されることにより所定のバイアス電圧が印加されている。また、他方の電極は、コンデンサ３、増幅器４を介してＭＣＡ５に接続されている。
[Configuration of radiation detector]
First, a schematic configuration of the radiation detector of the present embodiment will be described.
As shown in FIG. 1, the radiation detector 1 of this embodiment includes a radiation detection element 2, a capacitor 3, an amplifier 4, a multichannel analyzer (MCA) 5, and the like. The radiation detection element 2 has one electrode (common electrode 7) connected to the ground (grounded) and the other electrode (pixel electrode 8) connected to a negative potential so that a predetermined bias voltage is applied. . The other electrode is connected to the MCA 5 via the capacitor 3 and the amplifier 4.
放射線検出素子２の基板６は、II−VI族化合物半導体であるテルル化亜鉛カドミウム（ＣｄＺｎＴｅ（ＣｄＴｅ中のＣｄを例えば２〜９原子％程度Ｚｎで置き換えたもの））の結晶で形成されている。このＣｄＺｎＴｅが放射線（硬Ｘ線やγ線）を受けると電子を放出し、この電子がバイアス電圧により電離電流となり、コンデンサ３、増幅器４を経てパルス信号に変換される。そして、パルス信号がＭＣＡ５で解析され、放射線のスペクトルが得られる。
このようにして、本実施形態に係る放射線検出器１が構成されている。
The substrate 6 of the radiation detection element 2 is formed of a crystal of zinc cadmium telluride (CdZnTe (in which Cd in CdTe is replaced with, for example, about 2 to 9 atomic% Zn)), which is a II-VI group compound semiconductor. . When this CdZnTe receives radiation (hard X-rays or γ-rays), it emits electrons, and this electron becomes an ionization current by a bias voltage and is converted into a pulse signal through the capacitor 3 and the amplifier 4. Then, the pulse signal is analyzed by the MCA 5 to obtain a radiation spectrum.
Thus, the radiation detector 1 which concerns on this embodiment is comprised.
〔放射線検出素子の構成〕
次に、上記放射線検出素子の具体的構成について説明する。
図２に示すように、本実施形態の放射線検出素子２は、基板６、共通電極７、ピクセル電極８等で構成されている。
基板６は、薄い板状に形成されており、共通電極７およびピクセル電極８が形成される主面は、（１１１）面となっている。結晶方位[１１１]は、ＣｄＺｎＴｅにおける極性軸であるため、基板６の表面のうち一方の主面（以下Ａ面）６ａ側の表面組成はＣｄの割合が高く、他方の主面（以下Ｂ面）６ｂ側の表面組成はＴｅの割合が高くなっている。
[Configuration of radiation detection element]
Next, a specific configuration of the radiation detection element will be described.
As shown in FIG. 2, the radiation detection element 2 of the present embodiment includes a substrate 6, a common electrode 7, a pixel electrode 8, and the like.
The substrate 6 is formed in a thin plate shape, and the main surface on which the common electrode 7 and the pixel electrode 8 are formed is a (111) plane. Since the crystal orientation [111] is a polar axis in CdZnTe, the surface composition on the one main surface (hereinafter referred to as A surface) 6a side of the surface of the substrate 6 has a high Cd ratio, and the other main surface (hereinafter referred to as B surface). ) The surface composition on the 6b side has a high Te ratio.
共通電極（金属電極）７は、基板６のＢ面６ｂ全体を覆うように形成されている。ピクセル電極８（金属電極）は、基板６のＡ面６ａに複数設けられるとともに、マトリクス状（図では縦横４列）に配列されている。共通電極７およびピクセル電極８は共に白金（Ｐｔ）で薄膜状に形成されている。すなわち、基板６と共通電極１、基板６とピクセル電極８は共にオーミック接触している。以下、共通電極７とピクセル電極８を区別しない場合は、両電極を合わせてＰｔ電極７，８と称する。
また、図３に示すように、基板６の表層（ここではＡ面６ａ側）であって、その表面にＰｔ電極７，８（ここではピクセル電極８）の形成された部位、すなわち、基板のバルク結晶６１とＰｔ電極７，８との間には、主にＴｅの酸化物とＰｔからなる中間層６２が形成されている。
本実施形態の放射線検出素子２はこのようにして構成されている。
The common electrode (metal electrode) 7 is formed so as to cover the entire B surface 6 b of the substrate 6. A plurality of pixel electrodes 8 (metal electrodes) are provided on the A surface 6a of the substrate 6 and arranged in a matrix (4 rows in the figure). Both the common electrode 7 and the pixel electrode 8 are made of platinum (Pt) in a thin film shape. That is, both the substrate 6 and the common electrode 1 and the substrate 6 and the pixel electrode 8 are in ohmic contact. Hereinafter, when the common electrode 7 and the pixel electrode 8 are not distinguished from each other, the electrodes are collectively referred to as Pt electrodes 7 and 8.
Further, as shown in FIG. 3, the surface layer of the substrate 6 (here, the A surface 6a side) where the Pt electrodes 7 and 8 (here, the pixel electrode 8) are formed, that is, the substrate surface. Between the bulk crystal 61 and the Pt electrodes 7 and 8, an intermediate layer 62 mainly composed of an oxide of Te and Pt is formed.
The radiation detection element 2 of the present embodiment is configured in this way.
〔放射線検出素子の製造方法〕
次に、上記放射線検出素子の製造方法について説明する。
本実施形態の放射線検出素子２は、基板製造工程、電極形成工程、ダイシング工程を経て製造される。
はじめに行われる基板製造工程は、切断工程、研磨工程からなる。
切断工程では、ＣｄＺｎＴｅの単結晶インゴットを結晶面（１１１）に沿って切断することにより薄い円盤状のウエハー（基板６）を切り出す。
切断工程の後は、研磨工程に移る。研磨工程では、切り出したウエハーの切断面をアルミナ粉末等の研磨剤を用いて物理的に鏡面研磨する。この研磨工程は、ウエハー毎に複数回繰り返してもよい。
[Method of manufacturing radiation detection element]
Next, the manufacturing method of the said radiation detection element is demonstrated.
The radiation detection element 2 of this embodiment is manufactured through a substrate manufacturing process, an electrode forming process, and a dicing process.
The substrate manufacturing process performed first includes a cutting process and a polishing process.
In the cutting step, a CdZnTe single crystal ingot is cut along the crystal plane (111) to cut out a thin disk-shaped wafer (substrate 6).
After the cutting process, the process proceeds to the polishing process. In the polishing step, the cut surface of the cut wafer is physically mirror-polished using an abrasive such as alumina powder. This polishing process may be repeated multiple times for each wafer.
基板製造工程の後は電極形成工程に移る。電極形成工程は、電極パターン形成工程、めっき工程からなる。
電極パターン形成工程では、まず、基板製造工程で製造されたウエハーをメタノールに浸漬し、室温で３０秒間超音波洗浄することにより、ウエハーに付着した異物を除去する。そして、ウエハーの表面にフォトレジストを塗布し、ピクセル電極パターンが描かれたフォトマスクを用いてフォトレジストを露光する。そして、現像することにより感光したフォトレジストを除去する。そして、ウエハーを１容量％の臭素を混合したメタノール（ブロメタ液）に浸漬し、室温で３分間ウエハーの研磨面をエッチングして基板６の表面から加工変質層を除去する。そして、メタノールを用いてウエハーからブロメタ液を除去し、純水を用いてウエハーからメタノールを除去して電極パターン形成工程を終了する。
After the substrate manufacturing process, the process proceeds to an electrode forming process. An electrode formation process consists of an electrode pattern formation process and a plating process.
In the electrode pattern forming process, first, the wafer manufactured in the substrate manufacturing process is immersed in methanol, and ultrasonic cleaning is performed at room temperature for 30 seconds to remove foreign matters attached to the wafer. Then, a photoresist is applied to the surface of the wafer, and the photoresist is exposed using a photomask on which a pixel electrode pattern is drawn. Then, the exposed photoresist is removed by development. Then, the wafer is immersed in methanol (brometa solution) mixed with 1% by volume of bromine, and the polished surface of the wafer is etched at room temperature for 3 minutes to remove the work-affected layer from the surface of the substrate 6. Then, the brometa solution is removed from the wafer using methanol, the methanol is removed from the wafer using pure water, and the electrode pattern forming step is completed.
電極パターン形成工程の後はめっき工程に移る。めっき工程では、ウエハーを塩化白金酸（IV）六水和物水溶液に塩酸を混合しためっき液に浸漬することで、ウエハーの研磨面６ａ，６ｂのうちフォトレジストの除去された箇所にＰｔを析出させＰｔ層を形成する。このＰｔ層が所定の膜厚まで成長したものがＰｔ電極７，８となる。Ｐｔ電極７，８が形成された後は、不要になったフォトレジストを除去し、純水を用いてウエハーを洗浄する。そして、ウエハーおよびＰｔ電極７，８に窒素ガスを噴きつけることによりウエハーおよびＰｔ電極７，８を乾燥させて電極形成工程を終了する。 After the electrode pattern forming process, the process proceeds to the plating process. In the plating process, the wafer is immersed in a plating solution in which hydrochloric acid is mixed with an aqueous solution of chloroplatinic acid (IV) hexahydrate to deposit Pt on the polished surfaces 6a and 6b of the wafer where the photoresist has been removed. To form a Pt layer. The Pt layers 7 and 8 are formed by growing the Pt layer to a predetermined thickness. After the Pt electrodes 7 and 8 are formed, the unnecessary photoresist is removed and the wafer is washed with pure water. Then, nitrogen gas is sprayed onto the wafer and the Pt electrodes 7 and 8 to dry the wafer and the Pt electrodes 7 and 8, and the electrode forming process is completed.
電極形成工程の後はダイシング工程に移る。ダイシング工程では、研磨面６ａ，６ｂにＰｔ電極７，８が形成されたウエハーを切断して複数の基板６に分割するとともに、個々の放射線検出素子２をウエハーから切り出す。
以上の各工程を経ることにより、ＣｄＺｎＴｅ結晶で形成された基板６の表面にＴｅの酸化物を含む中間層６２を介してＰｔ電極７，８が形成されてなる放射線検出素子２が製造される。
After the electrode forming process, the process proceeds to a dicing process. In the dicing process, the wafer having the Pt electrodes 7 and 8 formed on the polished surfaces 6a and 6b is cut and divided into a plurality of substrates 6, and the individual radiation detection elements 2 are cut out from the wafer.
Through the above steps, the radiation detection element 2 is manufactured in which the Pt electrodes 7 and 8 are formed on the surface of the substrate 6 formed of CdZnTe crystal via the intermediate layer 62 containing Te oxide. .
〔中間層〕
次に、中間層６２について説明する。
基板６のバルク結晶６１とＰｔ電極７，８との間に介在する中間層６２は、上記めっき工程において無電解めっきを行う際に、基板６表層に含まれるＣｄとめっき液に含まれるＰｔとが置換されることにより形成される。すなわち、中間層６２は、基板６の表層のうちＰｔ電極７，８と接する部分が無電解めっきを行ったことにより変質したものである。
[Middle layer]
Next, the intermediate layer 62 will be described.
The intermediate layer 62 interposed between the bulk crystal 61 of the substrate 6 and the Pt electrodes 7 and 8 has Cd contained in the surface layer of the substrate 6 and Pt contained in the plating solution when electroless plating is performed in the plating step. Is formed by substitution. In other words, the intermediate layer 62 has been altered by performing electroless plating on the surface layer of the substrate 6 in contact with the Pt electrodes 7 and 8.
中間層６２は、めっきを行う際の各種条件によってその状態が変わってくる。例えば、中間層６２は、無電解めっきを行う前の基板６の表面状態により、その平均膜厚や膜厚の均一さが異なってくる。具体的には、上記研磨工程を３回繰り返し経て製造された基板と、１回のみ経て製造された基板に、それぞれ同様の条件で無電解白金めっきを行うと、研磨工程を３回経たものは、図４（ａ）に示すように、中間層６２の膜厚が均一になっているのに対し、１回だけ経たものは、図４（ｂ）に示すように、バルク結晶６１と中間層６２との境界面に起伏が大きく、中間層６２の膜厚が均一になっていないことがわかる。これは図５に示すＢ面についても同様である。 The state of the intermediate layer 62 changes depending on various conditions during plating. For example, the intermediate layer 62 has different average film thickness and film thickness uniformity depending on the surface state of the substrate 6 before electroless plating. Specifically, when electroless platinum plating is performed under the same conditions on a substrate manufactured by repeating the polishing process three times and a substrate manufactured only once, the polishing process is performed three times. As shown in FIG. 4 (a), the thickness of the intermediate layer 62 is uniform, whereas after passing only once, the bulk crystal 61 and the intermediate layer are formed as shown in FIG. 4 (b). It can be seen that the undulation is large at the boundary surface with 62 and the film thickness of the intermediate layer 62 is not uniform. The same applies to the B surface shown in FIG.
また、Ａ面に限れば、図４（ａ）に示した研磨工程を３回経たものは、図４（ｂ）に示した１回だけ経たものに比べ中間層が厚く形成されている。すなわち、基板６を製造する際に研磨工程を多く経るほど、中間層６２、Ｐｔ電極７，８共に膜厚を均一にすることができ、少なくともＡ面においては、厚い中間層６２を厚くすることが可能になるといえる。 Further, as far as the A surface is concerned, the intermediate layer formed thicker after the polishing process shown in FIG. 4 (a) three times than the one shown in FIG. 4 (b). That is, the more the polishing process is performed when the substrate 6 is manufactured, the more uniform the thickness of the intermediate layer 62 and the Pt electrodes 7 and 8 can be. At least in the A plane, the thick intermediate layer 62 is increased. Can be said to be possible.
また、発明者は、無電解めっきを行う際のＰｔの析出速度により、所定時間で形成される中間層６２の厚さが異なることを見出した。具体的には、Ｐｔの析出速度が速いとＣｄとＰｔの置換が充分に行われないので中間層６２は薄くなり、逆に、Ｐｔの析出速度が遅いとＣｄとＰｔの置換が基板６の深部まで行われるので中間層６２は厚くなる。
Ｐｔの析出速度を制御する方法としては、めっき液中の塩酸濃度の調節が効果的である。具体的には、塩酸濃度を高くすると析出速度を遅くすることができ、逆に、塩酸濃度を低くすると析出速度を速くすることができる。
The inventors have also found that the thickness of the intermediate layer 62 formed in a predetermined time varies depending on the deposition rate of Pt when performing electroless plating. Specifically, if the deposition rate of Pt is high, the substitution of Cd and Pt is not sufficiently performed, so that the intermediate layer 62 becomes thin. Conversely, if the deposition rate of Pt is slow, the substitution of Cd and Pt causes the substitution of the substrate 6. Since the process is performed to the deep part, the intermediate layer 62 becomes thick.
As a method for controlling the deposition rate of Pt, it is effective to adjust the hydrochloric acid concentration in the plating solution. Specifically, when the hydrochloric acid concentration is increased, the precipitation rate can be decreased, and conversely, when the hydrochloric acid concentration is decreased, the precipitation rate can be increased.
つまり、めっきを行う時間が同じであれば、めっき液中の塩酸濃度が高いほど中間層６２は厚く、Ｐｔ電極７，８は薄く形成され、塩酸濃度が低いほど中間層６２は薄く、Ｐｔ電極７，８は厚く形成されることになる。しかし、塩酸濃度が高い場合であっても、めっき時間を長くすることで、中間層６２、Ｐｔ電極７，８を共に厚くすることが可能である。 That is, if the plating time is the same, the intermediate layer 62 is thicker and the Pt electrodes 7 and 8 are thinner as the hydrochloric acid concentration in the plating solution is higher, and the intermediate layer 62 is thinner as the hydrochloric acid concentration is lower. 7 and 8 are formed thick. However, even when the hydrochloric acid concentration is high, it is possible to increase the thickness of both the intermediate layer 62 and the Pt electrodes 7 and 8 by increasing the plating time.
＜実施例＞
実施例では、まず、温度５０℃、濃度０．８ｇ／Ｌの塩化白金酸（IV）六水和物水溶液が等量ずつ入れられた７つの容器を用意し、各容器のうち１つの容器の水溶液には塩酸を加えず、他の６つの容器の水溶液には３５質量％の濃度の塩酸を、濃度がそれぞれ３，５、１０，２０，４０、６０ｍｌ／Ｌとなるように加えることより、塩酸濃度の異なる７種類のめっき液を用意した。そして、上記の原理を利用し、ＣｄＺｎＴｅの単結晶で形成した基板を、塩酸を含まないめっき液には３分間、塩酸を含む６つのめっき液のうち、濃度が３，５，１０，４０，６０ｍｌ／Ｌのものには１５分間、濃度が２０ｍｌ／Ｌのものには１５，３０分間それぞれ浸漬して無電解めっきを行ない、中間層の膜厚が異なる８種類のＰｔ電極のサンプル（比較例１，２、実施例１〜６）を作成した。下の表１は、各サンプルのめっき条件、Ｐｔ電極の膜厚、中間層の膜厚をそれぞれ示したものである。
<Example>
In the examples, first, seven containers each containing an equal amount of an aqueous solution of chloroplatinic acid (IV) hexahydrate having a temperature of 50 ° C. and a concentration of 0.8 g / L were prepared. By adding no hydrochloric acid to the aqueous solution and adding 35% by mass hydrochloric acid to the aqueous solution of the other six containers so that the concentrations are 3, 5, 10, 20, 40, and 60 ml / L, respectively. Seven types of plating solutions having different hydrochloric acid concentrations were prepared. Then, using the above principle, a substrate formed of a single crystal of CdZnTe is used for a plating solution that does not contain hydrochloric acid for 3 minutes, and the concentration is 3, 5, 10, 40, Electroless plating is performed by dipping for 15 minutes for 60 ml / L, and for 15 and 30 minutes for concentration of 20 ml / L. Samples of 8 types of Pt electrodes with different intermediate layer thicknesses (comparative examples) 1, 2, Examples 1-6) were prepared. Table 1 below shows the plating conditions of each sample, the thickness of the Pt electrode, and the thickness of the intermediate layer.
〔組成の比較〕
また、上記サンプルのうち、比較例１（両面とも中間層なし）と実施例３（中間層膜厚Ａ面０．３５μｍ、Ｂ面０．３μｍ）について、スパッタリングによるサンプル表面の削り取りとオージェ電子分光法によるサンプル表面の組成分析を交互に繰り返すことにより、Ｐｔ電極表面から基板へ向かう深さ方向（Ｐｔ電極表面に垂直な方向）の組成分析を行った。図６（ａ）は比較例１の（１１１）Ａ面側の組成分析をした結果であり、図６（ｂ）は実施例３の（１１１）Ａ面側の組成分析をした結果であり、横軸がスパッタリングの実行時間（電極表面から基板方向への深さに該当する）、縦軸が各元素のピーク強度である。
[Composition comparison]
Further, among the above samples, for Comparative Example 1 (no intermediate layer on both sides) and Example 3 (intermediate layer thickness A surface 0.35 μm, B surface 0.3 μm), scraping of the sample surface by sputtering and Auger electron spectroscopy By alternately repeating the composition analysis of the sample surface by the method, the composition analysis in the depth direction (direction perpendicular to the Pt electrode surface) from the Pt electrode surface to the substrate was performed. 6 (a) shows the result of the composition analysis on the (111) A plane side of Comparative Example 1, and FIG. 6 (b) shows the result of the composition analysis on the (111) A plane side of Example 3, The horizontal axis represents the sputtering execution time (corresponding to the depth from the electrode surface to the substrate direction), and the vertical axis represents the peak intensity of each element.
図６（ａ）に示すように、比較例１のサンプルでは、最表層（スパッタリング時間０〜約３分）でＰｔが検出されている。また、上記ＣｄＺｎＴｅ基板と最表層の中間部分（スパッタリング時間約１〜５分：Ａ１で示される範囲）では、その最表層側から上記基板側へ（深さ方向に）向かうにつれて、Ｔｅ，Ｃｄの濃度が急激に増加している。また、上記中間部分では、酸素（Ｏ）がスパッタリング時間約３分の箇所に濃度分布のピークを有するように分布していることがわかる。無電解めっきを行う前のＣｄＺｎＴｅ基板は、臭素２ｖｏｌ％濃度のメタノール液で表面処理されていて、その中に酸素は存在しないので、ここで酸素（Ｏ）が検出されるのは、めっき液に浸漬されている間にめっき液中の水分と上記中間部分中のＴｅが反応してＴｅの酸化物を形成したことによるものと考えられる。この酸素（Ｏ）が分布している範囲は、無電解めっきを行う前のＣｄＺｎＴｅ基板の表層に該当する部分と考えられ、比較例１のサンプルでは、上記最表層と上記ＣｄＺｎＴｅ基板との中間部分は、主にＴｅ，Ｃｄ，Ｏから構成されていることがわかる。 As shown to Fig.6 (a), in the sample of the comparative example 1, Pt is detected by the outermost layer (sputtering time 0 to about 3 minutes). Further, in an intermediate portion between the CdZnTe substrate and the outermost layer (sputtering time: about 1 to 5 minutes: a range indicated by A1), the direction of Te and Cd increases from the outermost layer side toward the substrate side (in the depth direction). Concentration is increasing rapidly. Also, it can be seen that oxygen (O) is distributed so as to have a concentration distribution peak at a position where the sputtering time is about 3 minutes in the intermediate portion. The CdZnTe substrate before the electroless plating is surface-treated with a 2 vol% bromine methanol solution, and oxygen is not present therein, so oxygen (O) is detected here in the plating solution. It is considered that the moisture in the plating solution and Te in the intermediate portion reacted to form Te oxide while being immersed. The range in which oxygen (O) is distributed is considered to correspond to the surface layer of the CdZnTe substrate before electroless plating. In the sample of Comparative Example 1, the intermediate portion between the outermost layer and the CdZnTe substrate. Is mainly composed of Te, Cd, and O.
これに対し、図６（ｂ）に示す実施例３では、図６（ａ）の比較例１と同様に、最表層においてＰｔが検出されている。図６（ｂ）の場合、Ｐｔの濃度分布は、スパッタリング時間で０〜約５分の範囲に広がっており、比較例１よりもＰｔが基板側へ深く混入している。また、最表面からＣｄＺｎＴｅ基板側へ組成分析を進めていくと、図６（ｂ）のスパッタリング時間が約２〜８分のＡ２で示される範囲では、Ｔｅ，Ｏが比較例１と同様の増加傾向を示しているのに対して、Ｃｄ濃度が減少している。また、Ｐｔが最表層近傍にピークを有し、緩やかに減少して、基板側へ混入している。つまり、実施例３のサンプルでは、比較例１の場合と異なり、この最表層とＣｄＺｎＴｅ基板の中間部分（実施例３のＡ２領域）で、上記基板中のＣｄとＰｔが置換して濃度分布に変化を起こしている。このＣｄとＰｔの置換されている領域（中間層）は、Ｔｅ、Ｏ及び微量のＰｔからなり、Ｃｄが殆ど含まれないことがわかる。なお、実施例３における中間層厚は約０．３５μｍであった。 On the other hand, in Example 3 shown in FIG. 6B, Pt is detected in the outermost surface layer as in Comparative Example 1 in FIG. In the case of FIG. 6B, the concentration distribution of Pt spreads in the range of 0 to about 5 minutes in terms of sputtering time, and Pt is mixed deeper into the substrate side than Comparative Example 1. Further, when the composition analysis proceeds from the outermost surface to the CdZnTe substrate side, Te and O increase in the same manner as in Comparative Example 1 within the range indicated by A2 of about 2 to 8 minutes in the sputtering time in FIG. In contrast to the trend, the Cd concentration decreases. Further, Pt has a peak in the vicinity of the outermost layer, gradually decreases, and enters the substrate side. That is, in the sample of Example 3, unlike the case of Comparative Example 1, Cd and Pt in the substrate are substituted into the concentration distribution in the intermediate portion (A2 region of Example 3) between this outermost layer and the CdZnTe substrate. It is changing. It can be seen that the region (intermediate layer) where Cd and Pt are substituted is composed of Te, O, and a small amount of Pt, and hardly contains Cd. The intermediate layer thickness in Example 3 was about 0.35 μm.
この分析の結果、塩酸を用いて無電解めっきを行うことにより形成される中間層６２は、塩酸を用いずに無電解めっきを行った際の基板表層と比べ、含有されるＣｄの割合に大きな相違があることが判明した。
なお、比較例１と実施例３との基板表層の組成の相違は、図７（ａ）に示す比較例１の（１１１）Ｂ面側の表層領域（スパッタリング時間約２〜５分：Ｂ１で示される範囲）と、図７（ｂ）に示す実施例３の（１１１）Ｂ面側の中間層（スパッタリング時間約２〜５分：Ｂ２で示される範囲）においても同様に見られる。
As a result of this analysis, the intermediate layer 62 formed by performing electroless plating using hydrochloric acid is larger in the proportion of Cd contained compared to the substrate surface layer when performing electroless plating without using hydrochloric acid. It turns out that there is a difference.
The difference in the composition of the substrate surface layer between Comparative Example 1 and Example 3 is that the surface layer region on the (111) B surface side of Comparative Example 1 shown in FIG. This is also the case with the intermediate layer on the (111) B surface side of Example 3 shown in FIG. 7B (sputtering time: about 2 to 5 minutes: the range indicated by B2).
〔基板とＰｔ電極の密着性評価〕
また、上記のようにして作成した各サンプルについて、ＪＩＳ・Ｈ８５０４に準拠した「めっきの密着性試験方法」のうち「テープ試験方法」により、基板６とＰｔ電極７，８との密着性を評価した。具体的には、各サンプルのＰｔ電極表面に、ＪＩＳ・Ｚ１５２２に規定された粘着テープ（幅２５ｍｍ当たり約８Ｎの粘着力、呼び幅１２〜１９ｍｍ）を貼り付け、気泡ができないように強く押し付ける。そして、粘着テープの端部を持ち、粘着テープをＰｔ電極表面に対して垂直方向に強く引っ張って瞬時に引き剥がす。そして、剥離したＰｔ膜の面積を測定し、剥離したＰｔ膜の面積が、粘着テープに貼り付いたＰｔ膜の面積全体の５％以下であったものを密着性良好（○）とし、５％を超えたものを密着性不良（×）とした。
[Evaluation of adhesion between substrate and Pt electrode]
In addition, for each sample prepared as described above, the adhesion between the substrate 6 and the Pt electrodes 7 and 8 is evaluated by the “tape test method” in the “plating adhesion test method” based on JIS / H8504. did. Specifically, an adhesive tape (adhesive strength of about 8N per 25 mm width, nominal width 12 to 19 mm) specified in JIS / Z1522 is applied to the surface of the Pt electrode of each sample, and pressed strongly so as not to generate bubbles. Then, holding the end of the adhesive tape, the adhesive tape is strongly pulled in the direction perpendicular to the surface of the Pt electrode, and is instantly peeled off. Then, the area of the peeled Pt film was measured, and when the peeled Pt film area was 5% or less of the total area of the Pt film attached to the adhesive tape, the adhesion was good (O), and 5% Those exceeding the range were defined as poor adhesion (x).
この試験の結果、表１に示したように、比較例１，２のサンプルは密着性不良（×）と判定され、実施例１〜５のサンプルはＡ，Ｂ面共に密着性良好（○）と判定された。つまり、中間層６２が無い又はその厚さが非常に薄いサンプルでは、基板６とＰｔ電極７，８の密着性が低く、中間層６２が厚い（０．１μｍ以上の）サンプルでは、Ａ，Ｂ面共に密着性が良好であることが判明した。特に、実施例３〜５のサンプルのように、中間層厚さが０．３５〜０．７０μｍのときには、剥離するＰｔ膜が粘着テープに貼り付いたＰｔ膜全体の１％未満となり、粘着性が極めて良好であった。
なお、本実施例では中間層厚０．７μｍを上限として密着性を評価したが、これより厚さが増しても密着性が低下することは無いものと思われる。しかし、中間層を厚くするほど塩酸が大量に必要になったり、めっきに時間がかかったりするので、密着性とコスト等のバランスを勘案し１μｍ程度を上限膜厚とするのが好ましい。
As a result of this test, as shown in Table 1, the samples of Comparative Examples 1 and 2 were determined to have poor adhesion (x), and the samples of Examples 1 to 5 had good adhesion on both A and B surfaces (◯). It was determined. That is, in the sample having no intermediate layer 62 or a very thin sample, the adhesion between the substrate 6 and the Pt electrodes 7 and 8 is low, and in the sample having a thick intermediate layer 62 (over 0.1 μm), A and B Both surfaces were found to have good adhesion. In particular, as in the samples of Examples 3 to 5, when the intermediate layer thickness is 0.35 to 0.70 μm, the Pt film to be peeled is less than 1% of the entire Pt film attached to the adhesive tape, and the adhesiveness Was very good.
In this example, the adhesiveness was evaluated with an intermediate layer thickness of 0.7 μm as the upper limit. However, it seems that the adhesiveness does not decrease even when the thickness is increased. However, the thicker the intermediate layer, the larger the amount of hydrochloric acid that is required, and the longer the plating takes. Therefore, it is preferable to set the upper limit thickness to about 1 μm in consideration of the balance between adhesion and cost.
〔素子特性〕
次に、放射線検出素子２の密着性以外の特性について説明する。
まず、本実施形態の放射線検出素子２と従来の放射線検出素子とで、リーク電流の量を比較した。その結果、本実施形態の放射線検出素子２は従来の放射線検出素子よりもバイアス電圧印加時のリーク電流を減少させることができることが判明した。リーク電流を少なくすることができれば、放射線検出素子２に更に高いバイアス電圧をかけることができるので、エネルギー分解能をより高めることができる。
(Element characteristics)
Next, characteristics other than the adhesion of the radiation detection element 2 will be described.
First, the amount of leakage current was compared between the radiation detection element 2 of the present embodiment and the conventional radiation detection element. As a result, it has been found that the radiation detection element 2 of the present embodiment can reduce the leakage current when a bias voltage is applied, as compared with the conventional radiation detection element. If the leakage current can be reduced, a higher bias voltage can be applied to the radiation detection element 2, so that the energy resolution can be further increased.
また、本実施形態の放射線検出素子２を用いた放射線検出器１と従来の放射線検出素子を用いた放射線検出器とで、得られる放射線スペクトルを比較した。その結果、本実施形態の放射線検出器１は、図８（ａ）に示すように、良好なスペクトルが得られるのに対し、従来の放射線検出器は、図９（ａ）に示すように、得られるスペクトルが良好でないことが見て取れる。これは、中間層６２からバルク結晶６１にかけてのＯおよびＣｄの組成勾配の緩急、すなわち、ＯおよびＣｄの組成勾配が、本実施形態の放射線検出素子２では、図８（ｂ）に示すように急になっているのに対し、従来の放射線検出素子では、図９（ｂ）に示すように緩やかになっていることが影響しているものと思われる。 Moreover, the radiation spectrum obtained was compared with the radiation detector 1 using the radiation detection element 2 of this embodiment, and the radiation detector using the conventional radiation detection element. As a result, the radiation detector 1 of the present embodiment can obtain a good spectrum as shown in FIG. 8 (a), while the conventional radiation detector as shown in FIG. 9 (a), It can be seen that the resulting spectrum is not good. This is because the composition gradient of O and Cd from the intermediate layer 62 to the bulk crystal 61, that is, the composition gradient of O and Cd is as shown in FIG. 8B in the radiation detection element 2 of the present embodiment. On the other hand, it seems that the conventional radiation detection element is affected by the gradual decrease as shown in FIG.
また、本実施形態の放射線検出器１と従来の放射線検出器２つとで、得られるスペクトルの半値幅（エネルギー分解能）を比較した。その結果、本実施形態の放射線検出器１は約１３％という半値幅が得られたのに対し、従来の放射線検出器では約１５．５％、１７％という半値幅が得られた。
また、本実施形態の放射線検出素子２の中間層６２におけるＴｅに対するＯ比（以下Ｏ／Ｔｅ）、および従来の放射線検出素子の表層におけるＯ／Ｔｅを調べた。その結果、本実施形態の放射線検出素子２はＯ／Ｔｅが約１００ａｔ％であったのに対し、従来の放射線検出素子では２つとも約６０ａｔ％であった。この結果を、横軸をＯ／Ｔｅ、縦軸を半値幅としてプロットしたところ、図１０に示すように、中間層６２または表層におけるＯ／Ｔｅが大きい、すなわち、中間層６２または表層にＯが多く含まれているほど、放射線検出素子２のエネルギー分解能が高まることが判明した。
Moreover, the half width (energy resolution) of the spectrum obtained was compared with the radiation detector 1 of this embodiment, and two conventional radiation detectors. As a result, the half width of about 13% was obtained with the radiation detector 1 of the present embodiment, whereas the half width of about 15.5% and 17% was obtained with the conventional radiation detector.
Further, the O ratio (hereinafter referred to as O / Te) to Te in the intermediate layer 62 of the radiation detection element 2 of the present embodiment and the O / Te in the surface layer of the conventional radiation detection element were examined. As a result, the radiation detection element 2 of the present embodiment had an O / Te of about 100 at%, whereas the two conventional radiation detection elements had about 60 at%. The results are plotted with the horizontal axis representing O / Te and the vertical axis representing the full width at half maximum. As shown in FIG. 10, O / Te in the intermediate layer 62 or the surface layer is large, that is, O is present in the intermediate layer 62 or the surface layer. It was found that the energy resolution of the radiation detection element 2 increases as the content increases.
このように、本実施形態の放射線検出素子２は、基板６の表層であってその表面にＰｔ電極７，８が形成される部位には、Ｔｅの酸化物を含む中間層６２が形成されているので、基板６とＰｔ電極７，８との密着性が高まり、Ｐｔ電極７，８が基板６から剥がれにくくなる。このため、製造時の歩留まりを向上させることができるとともに、その寿命を長くすることができる。
また、リーク電流が低減する、より精度の高い検出が可能となるなど素子特性を高めることもできる。
Thus, in the radiation detection element 2 of the present embodiment, the intermediate layer 62 containing the oxide of Te is formed on the surface layer of the substrate 6 where the Pt electrodes 7 and 8 are formed. Therefore, the adhesion between the substrate 6 and the Pt electrodes 7 and 8 is enhanced, and the Pt electrodes 7 and 8 are hardly peeled off from the substrate 6. For this reason, while improving the yield at the time of manufacture, the lifetime can be lengthened.
In addition, the device characteristics can be enhanced such that the leakage current is reduced and detection with higher accuracy is possible.
また、Ｔｅの割合が高い（１１１）Ｂ面は、従来（１１１）Ａ面に比べてＰｔ電極との密着性が低いとされてきたが、本実施形態のような中間層６２を形成することにより（１１１）Ｂ面６ｂとＰｔ電極７，８との密着性も向上させることができる。
更に、ピクセル電極８は基板６との接触面積が小さいことから、従来、共通電極に比べて密着性が劣り基板の（１１１）Ｂ面に形成することが困難であったが、本実施形態のような中間層６２を形成することによりピクセル電極８を（１１１）Ａ面６ａ，（１１１）Ｂ面６ｂの何れにも形成することができる。
Further, the (111) B surface having a high Te ratio has been considered to have lower adhesion to the Pt electrode than the conventional (111) A surface, but the intermediate layer 62 as in this embodiment is formed. Thus, the adhesion between the (111) B surface 6b and the Pt electrodes 7 and 8 can also be improved.
Furthermore, since the pixel electrode 8 has a small contact area with the substrate 6, conventionally, the pixel electrode 8 is inferior to the common electrode and has been difficult to form on the (111) B surface of the substrate. By forming such an intermediate layer 62, the pixel electrode 8 can be formed on either the (111) A surface 6a or the (111) B surface 6b.
また、本実施形態では、無電解めっきでＰｔ電極７，８を形成する際、塩酸を含むめっき液を用いることにより、基板６表層のＣｄとめっき液中のＰｔが置換され、基板６のバルク結晶６１とＰｔ電極７，８との間にＴｅの酸化物を含む中間層６２を形成することができる。
また、塩酸の濃度を高めることにより、Ｐｔの析出速度が遅くなり、Ｐｔ層がゆっくりと形成される。その間に基板６表層のＣｄとＰｔとの置換が基板の深部まで進み、厚く均一な中間層６２を形成しつつ薄く均一なＰｔ電極７，８を形成することができる。
In the present embodiment, when the Pt electrodes 7 and 8 are formed by electroless plating, the plating solution containing hydrochloric acid is used to replace Cd on the surface layer of the substrate 6 and Pt in the plating solution. An intermediate layer 62 containing an oxide of Te can be formed between the crystal 61 and the Pt electrodes 7 and 8.
Further, by increasing the concentration of hydrochloric acid, the deposition rate of Pt is reduced, and the Pt layer is slowly formed. Meanwhile, the substitution of Cd and Pt on the surface layer of the substrate 6 proceeds to the deep part of the substrate, and the thin and uniform Pt electrodes 7 and 8 can be formed while forming the thick and uniform intermediate layer 62.
以上、本発明者によってなされた発明を実施形態に基づいて具体的に説明したが、本発明は上記実施形態に限定されるものではなく、その要旨を逸脱しない範囲で変更可能である。
例えば、上記実施形態では、基板を形成する化合物半導体にＣｄＺｎＴｅ結晶を用いたが、ＣｄＴｅ結晶を用いてもよいし、ＣｄＺｎＴｅまたはＣｄＴｅに微量の不純物（塩素やインジウム）をドープしたものを用いてもよい。また、本実施形態では、ＣｄＺｎＴｅの単結晶インゴットを（１１１）面に沿って切断して切り出した基板を用いたが、他の結晶面（例えば（１１０）面、（１００）面など）に沿って切断して形成した基板を用いてもよい。
As mentioned above, although the invention made by this inventor was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.
For example, in the above embodiment, the CdZnTe crystal is used for the compound semiconductor that forms the substrate. However, the CdTe crystal may be used, or CdZnTe or CdTe doped with a small amount of impurities (chlorine or indium) may be used. Good. In the present embodiment, a substrate obtained by cutting and cutting a CdZnTe single crystal ingot along the (111) plane is used, but along other crystal planes (for example, the (110) plane, the (100) plane, etc.). A substrate formed by cutting may be used.
また、上記実施形態では金属電極をＰｔで形成する例を挙げたが、金（Ａｕ）で形成してもよいし、Ｐｔ単体の電極ではなく、Ｐｔを含む合金を用いたり、Ｐｔ層の上に更に他の金属の層を積層することで形成したりしてもよい。このようにすれば高価なＰｔの使用量を減らし、製造コストを下げることができる。
また、上記実施形態では基板６のＡ，Ｂ両面にＰｔ電極を形成したが、Ｂ面の電極をインジウム（Ｉｎ）やガリウム（Ｇａ）、アルミニウム（Ａｌ）で形成（ショットキー接合）してもよい。このようにすれば、両面をＰｔ電極とした場合に比べバイアス電圧印加時のリーク電流が抑えられ、放射線検出素子２に更に高い電圧を印加することができるので、エネルギー分解能が高まり、より精密な検出が可能となる。
Moreover, although the example which forms a metal electrode with Pt was given in the said embodiment, you may form with gold (Au), the alloy containing Pt may be used instead of the electrode of Pt single-piece | unit, or on the Pt layer In addition, another metal layer may be laminated. In this way, the amount of expensive Pt used can be reduced and the manufacturing cost can be reduced.
In the above embodiment, the Pt electrodes are formed on both sides A and B of the substrate 6. However, even if the B side electrodes are formed of indium (In), gallium (Ga), or aluminum (Al) (Schottky junction). Good. In this way, the leakage current at the time of bias voltage application can be suppressed and higher voltage can be applied to the radiation detection element 2 as compared with the case where both surfaces are Pt electrodes, so that the energy resolution is increased and more precise. Detection is possible.
また、無電解めっきに用いるめっき液に安定剤を添加するようにしてもよい。例えば、酢酸鉛を安定剤として添加しためっき液を用いることで、酢酸鉛を添加しないめっき液を用いる場合に比べ、中間層６２にできる空隙を少なくすることができるので、Ｐｔ電極７，８との密着性を更に高めることができる。 Moreover, you may make it add a stabilizer to the plating solution used for electroless plating. For example, by using a plating solution to which lead acetate is added as a stabilizer, it is possible to reduce the gaps that can be formed in the intermediate layer 62 as compared to the case of using a plating solution to which no lead acetate is added. The adhesion can be further improved.
今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
１ 放射線検出器
２ 放射線検出素子
６ 基板
６ａ Ａ面（主面）
６ｂ Ｂ面（主面）
６１ バルク結晶
６２ 中間層
７ 共通電極（金属電極）
８ ピクセル電極（金属電極）
DESCRIPTION OF SYMBOLS 1 Radiation detector 2 Radiation detection element 6 Board | substrate 6a A surface (main surface)
6b B side (main surface)
61 Bulk crystal 62 Intermediate layer 7 Common electrode (metal electrode)
8 Pixel electrode (metal electrode)
Claims (12)
前記基板の表層であってその表面に前記金属電極が形成される部位には、テルルの酸化物を含む中間層が形成されており、
前記中間層には、
テルルおよび酸素が、それぞれ前記基板の深さ方向に向かうに従って増加した後に減少するよう分布するとともに、
カドミウムが、テルルおよび酸素が最も多くなる深さ近傍から、前記基板の深さ方向に向かうに従って増加し始めるよう分布していることを特徴とする放射線検出素子。 Radiation comprising: a substrate formed of a compound semiconductor crystal containing cadmium telluride or zinc cadmium telluride; and a metal electrode formed of platinum or gold alone or an alloy containing platinum or gold on the surface of the substrate. In the detection element,
An intermediate layer containing tellurium oxide is formed on the surface of the substrate where the metal electrode is formed on the surface.
In the intermediate layer,
Tellurium and oxygen are distributed so as to decrease after increasing toward the depth of the substrate, respectively,
A radiation detecting element, wherein cadmium is distributed so as to start increasing from a vicinity of a depth at which tellurium and oxygen are maximized toward a depth direction of the substrate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2012017611A JP6120041B2 (en) | 2012-01-31 | 2012-01-31 | Radiation detection element and radiation detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2012017611A JP6120041B2 (en) | 2012-01-31 | 2012-01-31 | Radiation detection element and radiation detector |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2015197429A Division JP6018680B2 (en) | 2015-10-05 | 2015-10-05 | Manufacturing method of radiation detecting element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2013157494A JP2013157494A (en) | 2013-08-15 |
| JP6120041B2 true JP6120041B2 (en) | 2017-04-26 |
Family
ID=49052391
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2012017611A Active JP6120041B2 (en) | 2012-01-31 | 2012-01-31 | Radiation detection element and radiation detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6120041B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6129706B2 (en) * | 2013-09-27 | 2017-05-17 | Ｊｘ金属株式会社 | Compound semiconductor device manufacturing method and etching solution |
| JP2015072201A (en) * | 2013-10-03 | 2015-04-16 | 日立アロカメディカル株式会社 | Semiconductor radiation detector, nuclear medicine diagnostic device using semiconductor radiation detector, and semiconductor radiation detector manufacturing method |
| EP3279946B1 (en) * | 2015-03-31 | 2019-12-04 | JX Nippon Mining & Metals Corp. | Ubm electrode structure for radiation detector, radiation detector, and method for manufacturing said detector and structure |
| TWI683428B (en) | 2018-03-29 | 2020-01-21 | 日商Ｊｘ金屬股份有限公司 | Radiation detection element and its manufacturing method |
| US11721778B2 (en) | 2018-09-25 | 2023-08-08 | Jx Nippon Mining & Metals Corporation | Radiation detecting element and method for producing radiation detecting element |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08125203A (en) * | 1994-10-19 | 1996-05-17 | Japan Energy Corp | Manufacture of cdte element |
| JP2001177141A (en) * | 1999-12-20 | 2001-06-29 | Acrorad Co Ltd | Semiconductor device and method of manufacturing the same, and radioactive detector |
| JP2003142673A (en) * | 2001-11-07 | 2003-05-16 | Acrorad Co Ltd | Semiconductor radiation detecting element |
| US8314395B2 (en) * | 2009-08-31 | 2012-11-20 | General Electric Company | Semiconductor crystal based radiation detector and method of producing the same |
-
2012
- 2012-01-31 JP JP2012017611A patent/JP6120041B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2013157494A (en) | 2013-08-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP6120041B2 (en) | Radiation detection element and radiation detector | |
| EP3165947B1 (en) | Radiation detector ubm electrode structure body, radiation detector, and method of manufacturing same | |
| JP6018680B2 (en) | Manufacturing method of radiation detecting element | |
| Zheng et al. | Comparison of radiation detector performance for different metal contacts on CdZnTe deposited by electroless deposition method | |
| WO2019187217A1 (en) | Radiation detection element, and method for manufacturing same | |
| US20140217297A1 (en) | Array of Virtual Frisch-Grid Detectors with Common Cathode and Reduced Length of Shielding Electrodes | |
| WO2018012209A1 (en) | Radiation detector | |
| CN112585503A (en) | Photon-counting radiation detector and radiation inspection apparatus using the same | |
| JP6570619B2 (en) | UBM electrode structure for radiation detector, radiation detector and manufacturing method thereof | |
| CN114335238B (en) | Electrode structure of diamond particle detector and preparation method thereof | |
| Jones et al. | Study of surface passivation and Contact Deposition Techniques in CdZnTe X-Ray and gamma-ray detectors | |
| US6975012B2 (en) | Semiconductor radiation detector having voltage application means comprises InxCdyTez on CdTe semiconductor substrate | |
| Raulo et al. | Ion beam (RBS) and XRF analysis of metal contacts deposited on CdZnTe and CdTe crystals | |
| JP2001177141A (en) | Semiconductor device and method of manufacturing the same, and radioactive detector | |
| JPH08125203A (en) | Manufacture of cdte element | |
| WO2020066070A1 (en) | Radiation detection element and production method for radiation detection element | |
| JP5564928B2 (en) | DLTS measurement electrode and manufacturing method thereof | |
| JP4138673B2 (en) | Diamond sensor | |
| JPH0690291B2 (en) | Radiation detector | |
| JPH03201487A (en) | Manufacture of semiconductor radiation sensor | |
| JP6270498B2 (en) | Radiation detection element and method for manufacturing radiation detection element | |
| TW200924177A (en) | Ultraviolet detector | |
| JP2006303213A (en) | Semiconductor x-ray detection element and manufacturing method thereof | |
| CN112216749A (en) | Cadmium Zinc Telluride (CZT) crystal detector with high-resistance passivation layer and preparation method thereof | |
| Park et al. | Fabrication of CZT planar-type detectors and comparison of their performance |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20141009 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20150729 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20150804 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20151005 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20160322 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20160426 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20161004 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20161114 |
|
| A911 | Transfer to examiner for re-examination before appeal (zenchi) |
Free format text: JAPANESE INTERMEDIATE CODE: A911 Effective date: 20161121 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20170207 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20170215 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20170217 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20170307 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20170315 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6120041 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |