JP2006135190A

JP2006135190A - Photodiode array and spectroscope

Info

Publication number: JP2006135190A
Application number: JP2004324195A
Authority: JP
Inventors: Sadaji Takimoto; 貞治滝本
Original assignee: Hamamatsu Photonics KK
Current assignee: Hamamatsu Photonics KK
Priority date: 2004-11-08
Filing date: 2004-11-08
Publication date: 2006-05-25

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photodiode array which has a high wavelength resolution, a high optical responsive speed and a high light sensitivity, and a spectroscope which uses this photodiode array as a light detecting means. <P>SOLUTION: The photodiode array comprises a plurality of photodiodes 10 which have a planar shape which is a long and slender substantially rectangular shape, and are juxtaposed at a high density with long sides adjacent to each other, and an electrode 5 for extracting charges to be generated by entrance of lights. The photodiode 10 comprises a first conductive type low concentration impurity region 1 which contains a first conductive type impurity and constitutes a photosensitive region 7. A first conductive type high concentration impurity region 2 which contains the first conductive type impurity at a higher concentration than the first conductive type low concentration impurity region 1 and is formed in the photosensitive region 7 so as to extend in a long side direction. The first conductive type low concentration impurity region 1 and the first conductive type high concentration impurity region 2 are formed in a second conductive type impurity layer 3 containing a second conductive type impurity different from the first conductive type. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、ホトダイオードアレイと分光器とに関する。 The present invention relates to a photodiode array and a spectroscope.

ホトダイオードに係る技術としては、例えば、下記特許文献１などに開示されたものが知られている。このようなホトダイオードは、従来より様々な用途に用いられているが、特に、分光器の光検出手段として広く用いられている。
特開２００３−１５８２５１号公報 As a technique related to the photodiode, for example, one disclosed in Patent Document 1 below is known. Such photodiodes have been conventionally used for various applications, and in particular, are widely used as photodetection means for spectroscopes.
JP 2003-158251 A

ところで、分光器の光検出手段としては、高い波長分解能を高感度で実現するため、光が入射する光感応領域の平面形状が極端に細長い略矩形状（例えば、短辺の長さが２５〜５０μｍで、長辺の長さが略２．５ｍｍの略矩形状）を成す複数のフォトダイオードを長辺を相互に隣接させて並列且つ高密度で配置したものが知られている。この場合、光感応領域に発生するキャリアの電荷（以下、キャリア電荷という）を抽出するための電極が光感応領域の平面形状における一方の短辺側（二つの短辺のうち何れか一方の側であって、この短辺の近傍領域。以下同様）に設けられる。そして、個々のホトダイオードはそれぞれ一画素として構成される。 By the way, as a light detection means of a spectroscope, in order to realize high wavelength resolution with high sensitivity, the planar shape of the light sensitive region where light is incident is extremely long and narrow (for example, the length of the short side is 25 to 25). A plurality of photodiodes having a long side of approximately 2.5 mm and a long side of approximately 2.5 mm are arranged in parallel and at a high density with their long sides adjacent to each other. In this case, an electrode for extracting the charge of carriers generated in the photosensitive region (hereinafter referred to as carrier charge) is one short side of the planar shape of the photosensitive region (one of the two short sides). And in the vicinity of this short side (the same applies hereinafter). Each photodiode is configured as one pixel.

ここで、上記した分光器の光検出手段の一例を図を参照して説明する。図１２は分光器の光検出手段の構成を示す平面図であり、図１３はこの光検出手段に用いられるホトダイオードの構成を示す平面図である。この光検出手段は、ホトダイオード４０が一列に並列配置されたホトダイオードアレイ４１であり、このホトダイオードアレイ４１はそれぞれ光感応領域４２を有する複数のホトダイオード４０と、各ホトダイオード４０に設けられた電極４３と、この電極４３により抽出されたキャリア電荷を収集する読出部４４とが基板４５の表面に配置されている。特に、各ホトダイオード４０は、高い波長分解能を実現するため、光感応領域４２の平面形状を成す長辺を相互に隣接させるようにして並列配置され、さらに、この光感応領域４２の平面形状における一方の短辺側には電極４３が配置されている。そして、光感応領域４２には、例えば、Ｐ型（またはＮ型）の半導体領域４６が、Ｎ型（またはＰ型）の半導体層４７の表面に埋め込まれるように形成される。 Here, an example of the light detection means of the above-described spectroscope will be described with reference to the drawings. FIG. 12 is a plan view showing the configuration of the photodetecting means of the spectroscope, and FIG. 13 is a plan view showing the configuration of the photodiode used in the photodetecting means. This photodetecting means is a photodiode array 41 in which photodiodes 40 are arranged in parallel in a line. The photodiode array 41 includes a plurality of photodiodes 40 each having a photosensitive region 42, and electrodes 43 provided in each photodiode 40. A reading unit 44 that collects carrier charges extracted by the electrode 43 is arranged on the surface of the substrate 45. In particular, the photodiodes 40 are arranged in parallel so that the long sides forming the planar shape of the photosensitive region 42 are adjacent to each other in order to achieve high wavelength resolution. An electrode 43 is disposed on the short side of the. In the photosensitive region 42, for example, a P-type (or N-type) semiconductor region 46 is formed so as to be embedded in the surface of the N-type (or P-type) semiconductor layer 47.

ところで、分光器の光検出手段は、一般に、高い波長分解能が要求されるとともに、微弱な入射光でも高感度で検出できるような高い光感度も要求される。このため、この光検出手段として用いられるホトダイオード４０には非常に高い光感度が要求される。このように、ホトダイオード４０に高い光感度を実現させるためには、光感応領域４２を構成する不純物領域（以下、単に不純物領域という）の不純物濃度を低くすればよい。このことは、不純物領域の不純物濃度が高いと光応答速度は速くなるが光感度は低くなり、逆に、この不純物領域の不純物濃度が低いと光応答速度は遅くなるが光感度は高くなる、というホトダイオードの特性に由来している。ここで、光応答速度とは、光が照射されてから、光により不純物領域内に生じたキャリアが、電極４３により抽出されるまでの時間間隔を意味する。この光応答速度は、ＣＲの時定数により決まっており、不純物領域内の電気抵抗値が高い（不純物濃度が低い）と遅く、不純物領域内の電気抵抗値が低い（不純物濃度が高い）と速い。また、同じ電気抵抗値（不純物濃度）であっても、キャリアの発生地点と、このキャリア電荷を抽出する電極との距離に応じて光応答速度は異なったものとなる。 By the way, the photodetecting means of the spectroscope is generally required to have high wavelength resolution and high photosensitivity so that even weak incident light can be detected with high sensitivity. For this reason, the photodiode 40 used as the light detecting means is required to have very high light sensitivity. As described above, in order to achieve high photosensitivity in the photodiode 40, the impurity concentration of the impurity region (hereinafter simply referred to as impurity region) constituting the photosensitive region 42 may be lowered. This means that if the impurity concentration in the impurity region is high, the photoresponse speed is high but the photosensitivity is low. Conversely, if the impurity concentration in the impurity region is low, the photoresponse speed is slow but the photosensitivity is high. This is derived from the characteristics of the photodiode. Here, the light response speed means a time interval from the irradiation of light until the carriers generated in the impurity region by the light are extracted by the electrode 43. This optical response speed is determined by the time constant of CR, and is slow when the electric resistance value in the impurity region is high (impurity concentration is low), and fast when the electric resistance value in the impurity region is low (impurity concentration is high). . Even with the same electric resistance value (impurity concentration), the optical response speed differs depending on the distance between the generation point of carriers and the electrode from which the carrier charge is extracted.

しかし、光感度を高くしようとして不純物領域の不純物濃度を低くすると、電気抵抗値が高くなって逆に光応答速度が低下する、という問題が生じる。さらに、光感応領域４２のうち電極４３から遠い場所でキャリアが発生した場合、すなわち、光感応領域４２の平面形状を成す二つの短辺のうち電極４３が配置された側とは反対側に位置する短辺側にキャリアが発生した場合には、このキャリアは光感応領域４２の平面形状を成す長辺の長さに相当する距離を移動しなければ電極４３に到達できず、このため、光応答速度がさらに低下することとなる。 However, if the impurity concentration in the impurity region is lowered in order to increase the photosensitivity, there arises a problem that the electrical resistance value is increased and the light response speed is decreased. Further, when carriers are generated in a location far from the electrode 43 in the photosensitive region 42, that is, on the side opposite to the side on which the electrode 43 is disposed on the two short sides forming the planar shape of the photosensitive region 42. When the carrier is generated on the short side, the carrier cannot reach the electrode 43 unless the distance corresponding to the length of the long side forming the planar shape of the photosensitive region 42 is moved. The response speed is further reduced.

そこで、本発明の課題は、高い波長分解能、速い光応答速度および高い光感度を有するホトダイオードアレイと、このホトダイオードアレイを光検出手段として用いる分光器とを提供することである。 Accordingly, an object of the present invention is to provide a photodiode array having high wavelength resolution, fast light response speed and high light sensitivity, and a spectroscope using the photodiode array as a light detection means.

本発明によるホトダイオードアレイは、光が入射する光感応領域の平面形状が二つの長辺と二つの短辺とによって形作られる略矩形状を成すとともに、上記光感応領域の平面形状を成す長辺を互いに隣接させるように並列配置した複数のホトダイオードと、上記光感応領域に光が入射することによって発生する電荷を抽出するための電極と、を備え、上記ホトダイオードは、第１導電型不純物を含有して上記光感応領域を構成する第１の半導体領域と、上記第１導電型不純物を上記第１の半導体領域に比べて高濃度に含有して上記光感応領域の平面形状を成す長辺の向きに延びるように前記光感応領域に電気的に接続して形成され、前記電極に電気的に接続された第２の半導体領域とが、上記第１導電型とは異なる第２導電型の不純物を含有する第３の半導体層内に形成されている、ことを特徴とする。 The photodiode array according to the present invention has a substantially rectangular shape in which the planar shape of the photosensitive region where light is incident is formed by two long sides and two short sides, and the long side that forms the planar shape of the photosensitive region. A plurality of photodiodes arranged in parallel so as to be adjacent to each other; and an electrode for extracting charges generated when light enters the photosensitive region, wherein the photodiode contains a first conductivity type impurity. A first semiconductor region constituting the photosensitive region, and a direction of a long side containing the first conductivity type impurity at a higher concentration than the first semiconductor region to form a planar shape of the photosensitive region The second semiconductor region formed electrically connected to the photosensitive region and extending to the electrode and electrically connected to the electrode has impurities of a second conductivity type different from the first conductivity type. Contains The third is formed in the semiconductor layer that is characterized in that.

本発明のホトダイオードアレイによれば、ホトダイオードが、二つの長辺と二つの短辺とによって形作られる細長い略矩形状の光感応領域を有し、キャリア電荷を抽出するための電極が、この光感応領域の平面形状における所定位置に設けられ、さらに、長辺を互いに隣接させるように並列配置される。これにより、ホトダイオードを高密度に配置可能となり、ホトダイオードアレイを分光器に適用した場合に非常に高い波長分解能が実現できる。そして、ホトダイオードの光感応領域を構成する第１の半導体領域に電気的に接続されるように、この第１の半導体領域より不純物濃度が高く光応答速度が速い（電気抵抗値が低い、たとえばキャリア濃度１×１０^１８ｃｍ^−３以上）第２の半導体領域が形成され、さらに、この第２の半導体領域にキャリア電荷を抽出するための電極が電気的に接続される。このため、第１の半導体領域に光が照射されることにより生じるキャリア電荷が電気抵抗値の高い第１の半導体領域を移動することなく電気抵抗値の低い第２の半導体領域を移動して電極まで到達できるので、光応答速度が向上する。特に、第２の半導体領域が光感応領域の平面形状を成す長辺の向きに延びるように形成されるため、光感応領域のどの地点で発生したキャリアであっても（特に、電極が設けられた側とは反対に位置する短辺側で発生したキャリアであっても）、発生地点からすぐに第２の半導体領域に到達可能となり、より速い光応答速度が実現できる。さらに、第１の半導体領域の不純物濃度を低く、たとえばキャリア濃度１×１０^１７ｃｍ^−３以下に設定すれば、第１の半導体領域だけの光応答速度は遅いが（電気抵抗値が高いが）、全体としては光感度がよく、微弱な入射光でも感度良く検出可能となる。したがって、高い波長分解能、速い光応答速度および高い光感度を有するホトダイオードアレイが実現できる。 According to the photodiode array of the present invention, the photodiode has an elongated, substantially rectangular photosensitive region formed by two long sides and two short sides, and an electrode for extracting carrier charge is the photosensitive layer. It is provided at a predetermined position in the planar shape of the region, and is further arranged in parallel so that the long sides are adjacent to each other. As a result, the photodiodes can be arranged at high density, and a very high wavelength resolution can be realized when the photodiode array is applied to a spectrometer. Then, the impurity concentration is higher and the light response speed is faster than the first semiconductor region so as to be electrically connected to the first semiconductor region constituting the photosensitive region of the photodiode (for example, carrier resistance is low, for example, carrier) A concentration of 1 × 10 ¹⁸ cm ⁻³ or more) is formed, and an electrode for extracting carrier charges is electrically connected to the second semiconductor region. For this reason, the carrier charge generated by irradiating light to the first semiconductor region moves through the second semiconductor region having a low electrical resistance value without moving through the first semiconductor region having a high electrical resistance value. The light response speed is improved. In particular, since the second semiconductor region is formed so as to extend in the direction of the long side forming the planar shape of the photosensitive region, carriers generated at any point in the photosensitive region (particularly, electrodes are provided). Even if the carrier is generated on the short side opposite to the opposite side), the second semiconductor region can be reached immediately from the point of occurrence, and a faster optical response speed can be realized. Furthermore, if the impurity concentration of the first semiconductor region is low, for example, if the carrier concentration is set to 1 × 10 ¹⁷ cm ⁻³ or less, the optical response speed of only the first semiconductor region is slow (although the electric resistance value is high). As a whole, the photosensitivity is good and even weak incident light can be detected with good sensitivity. Therefore, a photodiode array having high wavelength resolution, fast light response speed and high light sensitivity can be realized.

また、本発明では、ホトダイオードは、上記電極が、上記光感応領域の平面形状を成す一方の短辺の近傍に設けられているのが好ましい。これにより、ホトダイオードを高密度に整列配置できるので、高い波長分解能を有するホトダイオードアレイが実現できる。 In the present invention, the photodiode is preferably provided in the vicinity of one short side forming the planar shape of the photosensitive region. As a result, the photodiodes can be arranged at high density, so that a photodiode array having high wavelength resolution can be realized.

また、本発明では、上記第２の半導体領域は、上記光感応領域の平面形状の外周に沿うように形成されているのが好ましい。これによれば、光感応領域の平面形状の外周に沿って第２の半導体領域が形成されるため、互いに導電型が異なる第１の半導体領域と第３の半導体層との界面がこの外周に沿っては形成されないこととなる。このため、ＳｉＯ_２層（またはＳｉＮ層）が光感応領域（第１の半導体領域）の表面に形成された場合であっても、この界面近傍に生じる空乏層が、第１の半導体領域（Ｓｉ領域）内で暗電流が生じるＳｉＯ_２層との界面近傍にまで拡大形成される、という現象が起こりにくくなる。このため、第１の半導体領域内における暗電流の増大化が抑制可能となり、低ノイズ化が実現できる。 In the present invention, the second semiconductor region is preferably formed along the outer periphery of the planar shape of the photosensitive region. According to this, since the second semiconductor region is formed along the outer periphery of the planar shape of the photosensitive region, the interface between the first semiconductor region and the third semiconductor layer having different conductivity types is formed on the outer periphery. It will not be formed along. For this reason, even when the SiO ₂ layer (or SiN layer) is formed on the surface of the photosensitive region (first semiconductor region), the depletion layer generated in the vicinity of the interface is not formed in the first semiconductor region (Si In the region), a phenomenon that the dark current is enlarged and formed near the interface with the SiO ₂ layer is less likely to occur. For this reason, an increase in dark current in the first semiconductor region can be suppressed, and a reduction in noise can be realized.

また、本発明による分光器は、入射光を分光する分光手段と、分光後の入射光の光量を電気信号に変換するための上記したホトダイオードアレイとを備えることを特徴とする。本発明の分光器によれば、光検出手段としてのホトダイオードアレイが高い波長分解能、速い光応答速度および高い光感度を有するため、高精度な分光器が実現できる。 In addition, a spectroscope according to the present invention is characterized by comprising spectroscopic means for splitting incident light and the above-described photodiode array for converting the amount of incident light after splitting into an electric signal. According to the spectrometer of the present invention, since the photodiode array as the light detecting means has high wavelength resolution, fast light response speed and high light sensitivity, a highly accurate spectrometer can be realized.

本発明によれば、高い波長分解能、速い光応答速度および高い光感度を有する低ノイズなホトダイオードアレイと、このホトダイオードアレイを光検出手段として用いる分光器とが提供できる。 According to the present invention, it is possible to provide a low-noise photodiode array having high wavelength resolution, fast light response speed and high light sensitivity, and a spectroscope using the photodiode array as a light detection means.

以下、図面を参照して、本実施形態に係るホトダイオードと、このホトダイオードを複数備えるホトダイオードアレイと、このホトダイオードアレイを光検出手段として用いる分光器とについて説明する。なお、以下の図面の説明においては、同一要素には同一符号を付し、重複説明は省略する。 Hereinafter, a photodiode according to the present embodiment, a photodiode array including a plurality of the photodiodes, and a spectroscope using the photodiode array as a light detection unit will be described with reference to the drawings. In the following description of the drawings, the same reference numerals are given to the same elements, and duplicate descriptions are omitted.

まず、図１〜図３に基づいて本実施形態に係るホトダイオードについて説明する。図１（ａ）は、本実施形態に係るホトダイオードの平面図であり、同図（ｂ）は、同図（ａ）に示すＩ−Ｉ矢示方向の断面構造を示す図であり、同図（ｃ）は、同図（ａ）に示すＩＩ−ＩＩ矢示方向の断面構造を示す図である。図２（ａ）は、本実施形態に係るホトダイオードに対し遮光膜が形成された場合の態様を示す平面図であり、同図（ｂ）は、同図（ａ）に示すＩＩＩ−ＩＩＩ矢示方向の断面構造を示す図である。そして、図３は、本実施形態に係るホトダイオードに生じる空乏層を説明するための図である。 First, the photodiode according to the present embodiment will be described with reference to FIGS. FIG. 1A is a plan view of the photodiode according to the present embodiment, and FIG. 1B is a diagram showing a cross-sectional structure in the direction of arrows I-I shown in FIG. (C) is a figure which shows the cross-section of the II-II arrow direction shown to the figure (a). FIG. 2A is a plan view showing a mode in which a light-shielding film is formed on the photodiode according to the present embodiment, and FIG. 2B is a cross-sectional view taken along the line III-III shown in FIG. It is a figure which shows the cross-sectional structure of a direction. And FIG. 3 is a figure for demonstrating the depletion layer produced in the photodiode which concerns on this embodiment.

まず、図１に基づいて、ホトダイオード１０の構成について説明する。ホトダイオード１０は、第１の半導体領域としての第１導電型低濃度不純物領域１と、第２の半導体領域としての第１導電型高濃度不純物領域２と、第３の半導体層としての第２導電型不純物層３と、シリコン熱酸化膜（ＳｉＯ_２であるが、ＳｉＮでも良い）４と、電極５，６と、光感応領域７とが形成される。ここで「第１導電型」と「第２導電型」とは、互いに異なる導電型（Ｎ型、Ｐ型）を意味する。すなわち、第１導電型がＰ型の場合には、第２導電型はＮ型であり、第１導電型がＮ型の場合には、第２導電型はＰ型である。以下、本実施形態においては、第１導電型を例えばＰ型として説明する。 First, the configuration of the photodiode 10 will be described with reference to FIG. The photodiode 10 includes a first conductivity type low concentration impurity region 1 as a first semiconductor region, a first conductivity type high concentration impurity region 2 as a second semiconductor region, and a second conductivity as a third semiconductor layer. A type impurity layer 3, a silicon thermal oxide film (SiO ₂ , but may be SiN) 4, electrodes 5 and 6, and a photosensitive region 7 are formed. Here, “first conductivity type” and “second conductivity type” mean different conductivity types (N-type and P-type). That is, when the first conductivity type is P type, the second conductivity type is N type, and when the first conductivity type is N type, the second conductivity type is P type. Hereinafter, in the present embodiment, the first conductivity type will be described as a P type, for example.

第１導電型低濃度不純物領域１は、シリコン（Ｓｉ）領域に、低濃度、たとえばキャリア濃度１×１０^１７ｃｍ^−３以下の第１導電型不純物（導電型がＮ型の場合には砒素などであり、Ｐ型の場合には硼素などである。以下同様）が含有されたものであり、第１導電型高濃度不純物領域２は、シリコン（Ｓｉ）領域に、第１導電型低濃度不純物領域１より高い濃度、たとえばキャリア濃度１×１０^１８ｃｍ^−３以上の第１導電型不純物が含有されたものである。 The first conductivity type low concentration impurity region 1 is formed in a silicon (Si) region with a first conductivity type impurity having a low concentration, for example, a carrier concentration of 1 × 10 ¹⁷ cm ⁻³ or less (arsenic or the like when the conductivity type is N type). In the case of the P type, boron or the like is contained, and the same applies to the first conductivity type high concentration impurity region 2 in the silicon (Si) region. A first conductivity type impurity having a concentration higher than that of region 1, for example, a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ or more is contained.

第１導電型低濃度不純物領域１は光感応領域７に形成され、第１導電型高濃度不純物領域２は第１導電型低濃度不純物領域１を取り囲むようにして形成される。また、第１導電型高濃度不純物領域２の厚さＬ２は第１導電型低濃度不純物領域１の厚さＬ１よりも厚くなるように設計されている。ここで、光感応領域７の平面形状は、二つの長辺と二つの短辺とによって形作られる略矩形状を成し、この平面形状における短辺側であってシリコン熱酸化膜４表面には電極５が形成される。電極５はシリコン熱酸化膜４を貫通して第１導電型高濃度不純物領域２と電気的に接続されている。 The first conductivity type low concentration impurity region 1 is formed in the photosensitive region 7, and the first conductivity type high concentration impurity region 2 is formed so as to surround the first conductivity type low concentration impurity region 1. Further, the thickness L2 of the first conductivity type high concentration impurity region 2 is designed to be thicker than the thickness L1 of the first conductivity type low concentration impurity region 1. Here, the planar shape of the photosensitive region 7 is a substantially rectangular shape formed by two long sides and two short sides, and is on the short side of the planar shape and on the surface of the silicon thermal oxide film 4. Electrode 5 is formed. The electrode 5 penetrates the silicon thermal oxide film 4 and is electrically connected to the first conductivity type high concentration impurity region 2.

そして、第１導電型低濃度不純物領域１と第１導電型高濃度不純物領域２とは第２導電型不純物層３の一方の表面にプレーナー状になるように形成され、さらに、その表面にシリコン熱酸化膜４が形成される。第２導電型不純物層３の上記表面とは反対側の表面には電極６が形成される。 The first-conductivity-type low-concentration impurity region 1 and the first-conductivity-type high-concentration impurity region 2 are formed on one surface of the second-conductivity-type impurity layer 3 so as to have a planar shape. A thermal oxide film 4 is formed. An electrode 6 is formed on the surface of the second conductivity type impurity layer 3 opposite to the surface.

さらに、本実施形態に係るホトダイオードアレイに並列配置されたホトダイオード１０の場合には、図２に示すような遮光膜８が、互いに隣接するホトダイオード１０の光感応領域７の間にあってシリコン熱酸化膜４の表面に形成される。図２には、図示簡略化のため、ホトダイオードアレイに並列配置される複数のホトダイオード１０のうちの二つが示されている。この遮光膜８は、例えば、ポリシリコン或いはＴｉＮなどの物質により構成される。 Further, in the case of the photodiode 10 arranged in parallel in the photodiode array according to the present embodiment, the light shielding film 8 as shown in FIG. 2 is located between the photosensitive regions 7 of the photodiodes 10 adjacent to each other, and the silicon thermal oxide film 4. Formed on the surface. FIG. 2 shows two of the plurality of photodiodes 10 arranged in parallel in the photodiode array for the sake of simplicity of illustration. The light shielding film 8 is made of a material such as polysilicon or TiN, for example.

上記構成を有するホトダイオード１０では、電極５，６間に電圧が印加された状態で光感応領域７に光が入射すると、光感応領域７を構成する第１導電型低濃度不純物領域１内の空乏層でキャリアが発生する。このキャリアは第１導電型低濃度不純物領域１や第１導電型高濃度不純物領域２内を移動して電極５に到達し、電極５によってそのキャリア電荷が抽出される。しかし、キャリアの移動速度は、第１導電型低濃度不純物領域１内よりも、第１導電型高濃度不純物領域２内のほうが速い（低電気抵抗）ため、第１導電型低濃度不純物領域１で発生するキャリアは、主に第１導電型高濃度不純物領域２内を移動して電極５に到達する。これにより、キャリアが第１導電型低濃度不純物領域１内のみを移動する場合に比べて移動速度が速くなり、光応答速度の向上が図られることとなる。さらに、光感応領域７が低不純物濃度の第１導電型低濃度不純物領域１により構成されるため、微弱な入射光も検出可能な高い光感度が実現できる。すなわち、本実施形態に係るホトダイオード１０によれば、高い光感度と速い光応答速度とが実現できる。尚、第２導電型高濃度不純物層３内に延びた空乏層でもキャリアが発生するが、このキャリアは第２導電型高濃度不純物層３内を移動して電極６に速やかに到達する。 In the photodiode 10 having the above configuration, when light is incident on the photosensitive region 7 with a voltage applied between the electrodes 5 and 6, the depletion in the first conductivity type low concentration impurity region 1 constituting the photosensitive region 7 is performed. Carriers are generated in the layer. The carriers move through the first conductivity type low concentration impurity region 1 and the first conductivity type high concentration impurity region 2 to reach the electrode 5, and the carrier charge is extracted by the electrode 5. However, the carrier movement speed is higher in the first conductivity type high concentration impurity region 2 than in the first conductivity type low concentration impurity region 1 (low electrical resistance). The carriers generated in (1) move mainly in the first conductivity type high concentration impurity region 2 and reach the electrode 5. As a result, the moving speed is increased as compared with the case where the carriers move only in the first conductivity type low-concentration impurity region 1, and the light response speed is improved. Furthermore, since the photosensitive region 7 is composed of the first conductivity type low-concentration impurity region 1 having a low impurity concentration, high photosensitivity capable of detecting even weak incident light can be realized. That is, according to the photodiode 10 according to the present embodiment, high light sensitivity and high light response speed can be realized. Note that carriers are also generated in the depletion layer extending into the second conductivity type high concentration impurity layer 3, but this carrier moves through the second conductivity type high concentration impurity layer 3 and quickly reaches the electrode 6.

また、上記したような第１導電型低濃度不純物領域１内に第１導電型高濃度不純物領域が形成されていないホトダイオードの場合には、図１４に示すように、半導体領域４６（光感応領域４２）や半導体層４７を含むＳｉ層と、このＳｉ層の表面に形成されるＳｉＯ_２層４８との界面近傍には、分子結合の電子対欠陥に起因する暗電流（ノイズ）が発生するが、特に、この界面が空乏層に接している場合には暗電流がより増大化されて大きくなる。したがってこの場合、半導体領域４６（光感応領域４２）の不純物濃度を低く設定すると、この半導体領域４６内にも空乏層が拡がるため、半導体領域４６内で生じる暗電流も増大化されて大きくなり、ノイズが増大する、という問題が生じる。これに対し、本実施例にかかるホトダイオード１０では、図３に示すように、第１導電型低濃度不純物領域１と第２導電型不純物層３との界面近傍に空乏層（図中符号Ａ１に示す点線で囲まれた領域）が生じるが、第１導電型高濃度不純物領域２が第１導電型低濃度不純物領域１（光感応領域７）を取り囲むようにして形成されるため、第１導電型低濃度不純物領域１内であって第１導電型低濃度不純物領域１とシリコン熱酸化膜４との界面近傍（例えば、図中符号Ａ２に示す一点鎖線で囲まれた領域）にまでこの空乏層が拡がる、という現象が起こりにくくなっている。このため、第１導電型低濃度不純物領域１とシリコン熱酸化膜４との界面近傍に生じる暗電流の増大化が抑制可能となり、低ノイズ化が実現できる。 In the case of the photodiode in which the first conductivity type high concentration impurity region 1 is not formed in the first conductivity type low concentration impurity region 1 as described above, as shown in FIG. 14, the semiconductor region 46 (photosensitive region) is formed. 42) or dark current (noise) due to electron-pair defects of molecular bonds occurs near the interface between the Si layer including the semiconductor layer 47 and the SiO ₂ layer 48 formed on the surface of the Si layer. In particular, when this interface is in contact with the depletion layer, the dark current is further increased and increased. Therefore, in this case, if the impurity concentration of the semiconductor region 46 (photosensitive region 42) is set low, the depletion layer also expands in the semiconductor region 46, so that the dark current generated in the semiconductor region 46 is increased and increased. There arises a problem that noise increases. On the other hand, in the photodiode 10 according to the present embodiment, as shown in FIG. 3, a depletion layer (indicated by reference numeral A1 in the figure) is provided in the vicinity of the interface between the first conductivity type low concentration impurity region 1 and the second conductivity type impurity layer 3. The first conductive type high concentration impurity region 2 is formed so as to surround the first conductive type low concentration impurity region 1 (photosensitive region 7). This depletion is within the type low-concentration impurity region 1 and to the vicinity of the interface between the first conductivity type low-concentration impurity region 1 and the silicon thermal oxide film 4 (for example, a region surrounded by a one-dot chain line indicated by reference numeral A2 in the figure). The phenomenon that the layer expands is less likely to occur. For this reason, an increase in dark current generated in the vicinity of the interface between the first conductivity type low-concentration impurity region 1 and the silicon thermal oxide film 4 can be suppressed, and a reduction in noise can be realized.

更に、図２に示されるように、第１導電型高濃度不純物領域２と第２導電型不純物層３との界面近傍を、遮光膜８で覆うことにより、空乏層が生じる第１導電型高濃度不純物領域２と第２導電型不純物層３との界面に光が入射することを防ぎ、分子結合の電子対欠陥に起因する暗電流（ノイズ）が光入射によって増大することを防ぐこともできる。 Further, as shown in FIG. 2, the first conductivity type high concentration in which a depletion layer is generated by covering the vicinity of the interface between the first conductivity type high concentration impurity region 2 and the second conductivity type impurity layer 3 with a light shielding film 8. Light can be prevented from entering the interface between the concentration impurity region 2 and the second conductivity type impurity layer 3, and dark current (noise) caused by electron-pair defects of molecular bonds can be prevented from increasing due to light incidence. .

ところで、上記特許文献１（特開２００３−１５８２５１号公報）に記載のホトダイオードは、本実施形態に係るホトダイオード１０のような、高い波長分解能が要求される分光器のホトダイオードアレイ（光検出手段）に設置できるような構成とはなっていない。すなわち、本発明に係るホトダイオードは、高い波長分解能を実現するためホトダイオードアレイに高密度に並列配置が可能な構成、すなわち、平面形状が細長い略矩形状を成し、キャリア電荷を抽出するための電極がこの平面形状における短辺側に設置された構成となっているが、上記文献に記載のホトダイオードはこのような構成にはなっていない。すなわち、本実施形態に係るホトダイオードアレイが備えるホトダイオードは、上記文献に記載のホトダイオードとは異なり、分光器に適用した場合に高い波長分解能と、十分に高い光感度および速い光応答速度とが実現できるものとなっている。 By the way, the photodiode described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-158251) is used as a photodiode array (photodetection means) of a spectrometer that requires a high wavelength resolution, such as the photodiode 10 according to the present embodiment. It is not configured to be installed. That is, the photodiode according to the present invention has a configuration that can be arranged in parallel with a photodiode array at high density in order to achieve high wavelength resolution, that is, an electrode for extracting carrier charges, having a substantially rectangular shape in plan view. However, the photodiode described in the above document does not have such a configuration. That is, unlike the photodiodes described in the above documents, the photodiodes included in the photodiode array according to the present embodiment can achieve high wavelength resolution, sufficiently high photosensitivity, and fast optical response speed when applied to a spectrometer. It has become a thing.

次に、本実施形態に係るホトダイオードアレイについて説明する。本実施形態に係るホトダイオードアレイの基本構成は、上記説明したホトダイオード１０を複数備え、このホトダイオード１０が光感応領域７の平面形状を成す長辺を相互に隣接させるようにして基板表面に高密度に並列配置されていることである。この場合、ホトダイオード１０に発生するキャリア電荷を抽出するための電極５は、できるだけ多くのホトダイオード１０を高密度に配置できるようにするため、光感応領域７の平面形状における短辺側にそれぞれ設けられている。 Next, the photodiode array according to the present embodiment will be described. The basic configuration of the photodiode array according to the present embodiment includes a plurality of the photodiodes 10 described above, and the photodiodes 10 have a high density on the substrate surface so that the long sides forming the planar shape of the photosensitive region 7 are adjacent to each other. It is arranged in parallel. In this case, the electrodes 5 for extracting the carrier charges generated in the photodiode 10 are respectively provided on the short side in the planar shape of the photosensitive region 7 so that as many photodiodes 10 as possible can be arranged at high density. ing.

上記のような基本構成を有する四タイプのホトダイオードアレイを図４に示す。図４（ａ）〜（ｄ）は、何れも、本実施形態に係るホトダイオードアレイを示す平面図である。 FIG. 4 shows four types of photodiode arrays having the above basic configuration. 4A to 4D are all plan views showing the photodiode array according to this embodiment.

図４（ａ）に示すホトダイオードアレイ２１は、モノリシック型であって、シフトレジスタ２０ｂに接続された複数のホトダイオード１０が光感応領域７の平面形状を成す長辺を相互に隣接させるようにして基板２０ａ表面に一列に並列配置されたものである。そして図４（ｂ）に示すホトダイオードアレイ２２は、同じくモノリシック型であって、シフトレジスタ２０ｂに接続された複数のホトダイオード１０が光感応領域７の平面形状を成す長辺を相互に隣接させるようにして基板２０ａ表面に並列配置されたものを複数列（図４に示す例では、二列）設けたものである。また、図４（ｃ）に示すホトダイオードアレイ２３は、チップ別体構造であって、読出し回路２０ｃに接続された複数のホトダイオード１０が光感応領域７の平面形状を成す長辺を相互に隣接させるようにして基板２０ａ表面に一列に並列配置されたものである。そして図４（ｄ）に示すホトダイオードアレイ２４は、チップ別体構造であるが、複数の基板２０ａ（図４に示す例では、二枚）を有し、各基板２０ａの表面には、それぞれ、読出し回路２０ｃに接続された複数のホトダイオード１０が光感応領域７の平面形状を成す長辺を相互に隣接させるようにして一列に並列配置されている。 The photodiode array 21 shown in FIG. 4A is a monolithic type, and is a substrate in which a plurality of photodiodes 10 connected to the shift register 20b are adjacent to each other with long sides forming the planar shape of the photosensitive region 7. These are arranged in parallel on the surface of 20a. The photodiode array 22 shown in FIG. 4B is also of a monolithic type, and a plurality of photodiodes 10 connected to the shift register 20b are adjacent to each other with long sides forming the planar shape of the photosensitive region 7. A plurality of rows (two rows in the example shown in FIG. 4) arranged in parallel on the surface of the substrate 20a are provided. Also, the photodiode array 23 shown in FIG. 4C has a separate chip structure, and a plurality of photodiodes 10 connected to the readout circuit 20c are adjacent to each other with long sides forming the planar shape of the photosensitive region 7. In this way, they are arranged in parallel in a row on the surface of the substrate 20a. The photodiode array 24 shown in FIG. 4 (d) has a separate chip structure, but has a plurality of substrates 20a (two in the example shown in FIG. 4). A plurality of photodiodes 10 connected to the readout circuit 20c are arranged in parallel in a row so that the long sides forming the planar shape of the photosensitive region 7 are adjacent to each other.

ここで、モノリシック型とは、基板２０ａにシフトレジスタ２０ｂを備え、このシフトレジスタ２０ｂによって複数のホトダイオード１０の受光量がシリアルデータとして出力可能となっている。これに対し、チップ別体構造とは、半導体チップ（この場合、シフトレジスタ２０ｂを含む読出し回路２０ｃ）が基板２０ａとは別体に設けられた構成のホトダイオードアレイであり、外部に設けられた読出し回路２０ｃと、基板２０ａに設けられた各ホトダイオード１０との間がワイヤ２０ｄによって電気的に接続されたものである。 Here, the monolithic type includes a shift register 20b on a substrate 20a, and the shift register 20b can output the received light amounts of a plurality of photodiodes 10 as serial data. On the other hand, the chip-separated structure is a photodiode array having a configuration in which a semiconductor chip (in this case, a read circuit 20c including the shift register 20b) is provided separately from the substrate 20a. The circuit 20c and each photodiode 10 provided on the substrate 20a are electrically connected by a wire 20d.

このホトダイオードアレイ２１〜２４によれば、ホトダイオード１０が基板２０ａに高密度で配置可能となるので高い波長分解能が実現できる。 According to the photodiode arrays 21 to 24, the photodiodes 10 can be arranged on the substrate 20a with high density, so that high wavelength resolution can be realized.

次に、図５を参照して、本実施形態に係る分光器３０について説明する。図５は、本実施形態に係る分光器を示す斜視図である。 Next, the spectrometer 30 according to the present embodiment will be described with reference to FIG. FIG. 5 is a perspective view showing the spectrometer according to the present embodiment.

図示のように、分光器３０は、光ファイバ３１、入射部３２、回折格子部３３、ミラー３４、基台３５、光検出手段３６などを備える。入射部３２は光ファイバ３１の端部を固定し、分光手段としての回折格子部３３は光ファイバ３１を通じて入射した光を回折させ、ミラー３４は光ファイバ３１から入射した光を回折格子部３３に向けて反射させるとともに回折格子部３３により回折された光を光検出手段３６に向けて反射させる。また、光検出手段３６は、回折格子部３３によって回折された光の光量を波長ごとに電気信号に変換するためのものであり、本実施形態に係るホトダイオードアレイ２１〜２４の何れかが用いられる。そして、入射部３２、回折格子部３３、ミラー３４、光検出手段３６は基台３５に設置される。 As shown in the figure, the spectroscope 30 includes an optical fiber 31, an incident part 32, a diffraction grating part 33, a mirror 34, a base 35, a light detection means 36, and the like. The incident part 32 fixes the end of the optical fiber 31, the diffraction grating part 33 as a spectroscopic means diffracts the light incident through the optical fiber 31, and the mirror 34 causes the light incident from the optical fiber 31 to enter the diffraction grating part 33. The light reflected by the diffraction grating portion 33 is reflected toward the light detection means 36. The light detection means 36 is for converting the amount of light diffracted by the diffraction grating section 33 into an electrical signal for each wavelength, and any one of the photodiode arrays 21 to 24 according to the present embodiment is used. . The incident portion 32, the diffraction grating portion 33, the mirror 34, and the light detection means 36 are installed on the base 35.

このように、本実施形態に係るホトダイオードアレイ２１〜２４を光検出手段として用いた分光器３０は、光検出手段３６（すなわち、ホトダイオードアレイ２１〜２４のいずれか）に用いられるホトダイオード１０が、低暗電流（低ノイズ）であるとともに高い光感度と速い光応答速度とを有するので、高い波長分解能を維持しつつ極めて精度の高い分光器となる。 As described above, the spectroscope 30 using the photodiode arrays 21 to 24 according to the present embodiment as the light detection means has a low photodiode 10 used for the light detection means 36 (that is, any one of the photodiode arrays 21 to 24). Since it has dark current (low noise) and high photosensitivity and fast photoresponse speed, it becomes a spectroscope with extremely high accuracy while maintaining high wavelength resolution.

なお、本発明は、上記説明したホトダイオードアレイ２１〜２４やホトダイオード１０に限らず、詳細構成や詳細動作については変更可能である。 The present invention is not limited to the photodiode arrays 21 to 24 and the photodiode 10 described above, and the detailed configuration and detailed operation can be changed.

例えば、ホトダイオード１０に替えて、図６〜図９に示すホトダイオード１０ａ〜１０ｄを用いてもよい。図６〜図９は、それぞれ本実施形態に係るホトダイオードの第１〜４の変形例を示す図である。なお、以下では、説明簡略化のため、第１導電型高濃度不純物領域２の立体的な形成領域（位置や形状）の説明を、平面形状を用いて行う。 For example, photodiodes 10a to 10d shown in FIGS. 6 to 9 may be used in place of the photodiode 10. 6 to 9 are diagrams showing first to fourth modifications of the photodiode according to the present embodiment, respectively. Hereinafter, for simplification of description, the three-dimensional formation region (position and shape) of the first conductivity type high concentration impurity region 2 will be described using a planar shape.

＜第１の変形例＞図６（ａ）は、本実施形態に係る第１の変形例としてのホトダイオードを示す平面図であり、同図（ｂ）は同図（ａ）に示すＩＶ−ＩＶ矢示方向の断面構造を示す図であり、同図（ｃ）は同図（ａ）に示すＶ−Ｖ矢示方向の断面構造を示す図である。図６に示すホトダイオード１０ａは、第１導電型高濃度不純物領域２の厚さＬ２が第１導電型低濃度不純物領域１の厚さＬ１よりも薄くなっており、この点を除けば、ホトダイオード１０ａの構成は上記した図１に示すホトダイオード１０と同様のものとなっている。 <First Modification> FIG. 6A is a plan view showing a photodiode as a first modification according to the present embodiment, and FIG. 6B is a IV-IV shown in FIG. It is a figure which shows the cross-section of an arrow direction, and the figure (c) is a figure which shows the cross-section of the VV arrow direction shown to the figure (a). In the photodiode 10a shown in FIG. 6, the thickness L2 of the first conductivity type high concentration impurity region 2 is smaller than the thickness L1 of the first conductivity type low concentration impurity region 1. Except for this point, the photodiode 10a The configuration is the same as that of the photodiode 10 shown in FIG.

＜第２の変形例＞図７（ａ）は、本実施形態に係る第２の変形例としてのホトダイオードを示す平面図であり、同図（ｂ）は同図（ａ）に示すＶＩ−ＶＩ矢示方向の断面構造を示す図であり、同図（ｃ）は同図（ａ）に示すＶＩＩ−ＶＩＩ矢示方向の断面構造を示す図である。図７に示すホトダイオード１０ｂは、第１導電型高濃度不純物領域２が、電極５を含む光感応領域７の平面形状における短辺側に位置する略矩形状領域に形成されると共に、当該形成された略矩形状領域に連結して光感応領域７の平面形状における略中央部で長辺の向きに延びる略直線状領域に形成される。そして、第１導電型低濃度不純物領域１の厚さＬ１が第１導電型高濃度不純物領域２の厚さＬ２よりも薄くなっている。 <Second Modification> FIG. 7A is a plan view showing a photodiode as a second modification according to this embodiment, and FIG. 7B is a VI-VI shown in FIG. It is a figure which shows the cross-sectional structure of an arrow direction, and the same figure (c) is a figure which shows the cross-sectional structure of the VII-VII arrow direction shown to the same figure (a). In the photodiode 10b shown in FIG. 7, the first conductivity type high-concentration impurity region 2 is formed in a substantially rectangular region located on the short side in the planar shape of the photosensitive region 7 including the electrode 5, and is formed. The light-sensitive region 7 is formed in a substantially linear region extending in the direction of the long side at the substantially central portion in the planar shape of the light-sensitive region 7. The thickness L1 of the first conductivity type low concentration impurity region 1 is smaller than the thickness L2 of the first conductivity type high concentration impurity region 2.

＜第３の変形例＞図８（ａ）は、本実施形態に係る第３の変形例としてのホトダイオード示す平面図であり、同図（ｂ）は同図（ａ）に示すＶＩＩＩ−ＶＩＩＩ矢示方向の断面構造を示す図であり、同図（ｃ）は同図（ａ）に示すＩＸ−ＩＸ矢示方向の断面構造を示す図である。図８に示すホトダイオード１０ｃは、第１導電型高濃度不純物領域２が、電極５の下に形成されると共に、当該形成された領域に連結して光感応領域７の平面形状の略中央部で長辺の向きに延びる略直線状領域に形成される。そして、第１導電型高濃度不純物領域２の厚さＬ２が第１導電型低濃度不純物領域１の厚さＬ１よりも薄くなっている。 <Third Modification> FIG. 8A is a plan view showing a photodiode as a third modification according to the present embodiment, and FIG. 8B is a VIII-VIII arrow shown in FIG. It is a figure which shows the cross-sectional structure of a shown direction, and the same figure (c) is a figure which shows the cross-sectional structure of the IX-IX arrow direction shown to the same figure (a). In the photodiode 10c shown in FIG. 8, the first conductivity type high-concentration impurity region 2 is formed below the electrode 5 and connected to the formed region at the substantially central portion of the planar shape of the photosensitive region 7. It is formed in a substantially linear region extending in the direction of the long side. The thickness L2 of the first conductivity type high concentration impurity region 2 is smaller than the thickness L1 of the first conductivity type low concentration impurity region 1.

＜第４の変形例＞図９（ａ）は、本実施形態に係る第４の変形例としてのホトダイオードを示す平面図であり、同図（ｂ）は同図（ａ）に示すＸ−Ｘ矢示方向の断面構造を示す図であり、同図（ｃ）は同図（ａ）に示すＸＩ−ＸＩ矢示方向の断面構造を示す図である。図９に示すホトダイオード１０ｄは、第１導電型高濃度不純物領域２が、電極５を含む光感応領域７の平面形状における短辺側に位置する略矩形状領域に形成されると共に、当該形成された略矩形状領域に連結して光感応領域７の平面形状を成す長辺の向きにジグザグ状に延びる領域に形成される。そして、第１導電型低濃度不純物領域１の厚さＬ１が第１導電型高濃度不純物領域２の厚さＬ２よりも薄くなっている。 <Fourth Modification> FIG. 9A is a plan view showing a photodiode as a fourth modification according to the present embodiment, and FIG. 9B is a cross-sectional view taken along line XX shown in FIG. It is a figure which shows the cross-sectional structure of an arrow direction, and the same figure (c) is a figure which shows the cross-sectional structure of the XI-XI arrow direction shown to the same figure (a). In the photodiode 10d shown in FIG. 9, the first conductivity type high concentration impurity region 2 is formed in a substantially rectangular region located on the short side in the planar shape of the photosensitive region 7 including the electrode 5, and is formed. It is formed in a region extending in a zigzag shape in the direction of the long side that is connected to the substantially rectangular region and forms the planar shape of the photosensitive region 7. The thickness L1 of the first conductivity type low concentration impurity region 1 is smaller than the thickness L2 of the first conductivity type high concentration impurity region 2.

上記した第１〜４の変形例としてのホトダイオード１０ａ〜１０ｄは、第１導電型高濃度不純物領域２の形成領域が、何れも電極５に電気的に接続された構成となっている。すなわち、ホトダイオード１０ａ〜１０ｄは、第１導電型高濃度不純物領域２を移動するキャリアのキャリア電荷が電極５によって抽出される構成となっている。 The photodiodes 10a to 10d as the first to fourth modifications described above are configured such that the formation region of the first conductivity type high concentration impurity region 2 is electrically connected to the electrode 5. That is, the photodiodes 10 a to 10 d are configured such that the carrier charges of the carriers moving through the first conductivity type high concentration impurity region 2 are extracted by the electrode 5.

ここで、上記した第１〜４の変形例に対して遮光膜８が形成された場合の態様について、特に、第２の変形例に係るホトダイオード１０ｂを用いて示す。図１０は、本実施例に係るホトダイオードに対し遮光膜が形成された場合の態様を示す平面図であり、同図（ｂ）は同図（ａ）に示すＸＩＩ−ＸＩＩ矢示方向の断面構造を示す図である。図１０に示すように、ホトダイオード１０ａがホトダイオードアレイ２１〜２４の基板２０ａ表面に並列配置された際には、互いに隣接するホトダイオード１０ａの光感応領域７の間にあってシリコン熱酸化膜４の表面に遮光膜８が形成される。ここで図１０には、図示簡略化のため、並列配置される複数のホトダイオード１０ａのうちの二つのみが示されている。 Here, an aspect in the case where the light shielding film 8 is formed with respect to the above-described first to fourth modifications will be described using the photodiode 10b according to the second modification. FIG. 10 is a plan view showing a mode in which a light-shielding film is formed on the photodiode according to the present embodiment, and FIG. 10B is a cross-sectional structure in the direction of arrows XII-XII shown in FIG. FIG. As shown in FIG. 10, when the photodiode 10a is arranged in parallel on the surface of the substrate 20a of the photodiode arrays 21 to 24, the light is shielded from the surface of the silicon thermal oxide film 4 between the photosensitive regions 7 of the adjacent photodiodes 10a. A film 8 is formed. Here, only two of the plurality of photodiodes 10a arranged in parallel are shown in FIG.

＜その他の変形例＞以上、本実施形態に係るホトダイオード１０の第１〜４の変形例について説明したが、上記第１〜４の変形例に限らず、第１導電型高濃度不純物領域２の形成領域の幾何学的形状の違いに応じて、本実施形態に係るさらに多くの変形例が存在する。このような変形例を図１１に四つ例示する。図１１（ａ）〜（ｄ）は、何れも、本実施形態に係るホトダイオードの他の変形例を示す平面図である。 <Other Modifications> The first to fourth modifications of the photodiode 10 according to this embodiment have been described above. However, the present invention is not limited to the first to fourth modifications. There are many variations according to the present embodiment depending on the difference in the geometric shape of the formation region. Four such modifications are illustrated in FIG. FIGS. 11A to 11D are plan views showing other modified examples of the photodiode according to the present embodiment.

図１１（ａ）に示すホトダイオード１０ｅは、第１導電型高濃度不純物領域２が、光感応領域７の平面形状の外周に沿って閉じた帯状領域に形成されると共に、当該形成された帯状領域に連結して光感応領域７の平面形状における略中央部で長辺の向きに細長く延びる略矩形状領域に形成されたものとなっている。そして、図１１（ｂ）に示すホトダイオード１０ｆは、第１導電型高濃度不純物領域２が、光感応領域７の平面形状の外周のうち、二つの長辺と一方の短辺とに沿うと共に他方の短辺側には開いた帯状領域に形成されたものとなっている。 In the photodiode 10e shown in FIG. 11A, the first conductivity type high-concentration impurity region 2 is formed in a band-shaped region closed along the planar outer periphery of the photosensitive region 7, and the formed band-shaped region Are formed in a substantially rectangular region that is elongated in the direction of the long side at the substantially central portion in the planar shape of the photosensitive region 7. In the photodiode 10f shown in FIG. 11B, the first conductivity type high-concentration impurity region 2 is along the two long sides and one short side of the planar outer periphery of the photosensitive region 7, and the other It is formed in an open belt-like region on the short side.

図１１（ｃ）に示すホトダイオード１０ｇは、第１導電型高濃度不純物領域２が、各々光感応領域７の平面形状を成す短辺の向きに細く延びる（すなわち、光感応領域７の平面形状を成す二つの長辺を結ぶような）複数の略矩形状領域に形成されると共に、当該形成された複数の略矩形状領域に連結して光感応領域７の平面形状の略中央部で長辺の向きに細長く延びる略矩形状領域に形成されたものとなっている。そして、図１１（ｄ）に示すホトダイオード１０ｈは、第１導電型高濃度不純物領域２が光感応領域７の平面形状を成す長辺の向きに細くジグザグ状に延びる領域に形成されたものとなっている。 In the photodiode 10g shown in FIG. 11C, the first conductivity type high-concentration impurity region 2 extends thinly in the direction of the short side that forms the planar shape of the photosensitive region 7 (that is, the planar shape of the photosensitive region 7 changes). Formed in a plurality of substantially rectangular regions (such as connecting two long sides formed) and connected to the formed plurality of substantially rectangular regions, and the long side at the substantially central portion of the planar shape of the photosensitive region 7 It is formed in a substantially rectangular region that is elongated in the direction of. The photodiode 10h shown in FIG. 11 (d) is formed in a region where the first conductivity type high concentration impurity region 2 is thinly extended in a zigzag shape in the direction of the long side forming the planar shape of the photosensitive region 7. ing.

ここで、上記したホトダイオード１０ｅ〜１０ｈは、何れも、第１導電型高濃度不純物領域２の形成領域が電極５に電気的に接続された構成となっており、第１導電型高濃度不純物領域２を移動するキャリアのキャリア電荷が電極５により抽出されるものである。 Here, each of the photodiodes 10e to 10h described above has a configuration in which the formation region of the first conductivity type high concentration impurity region 2 is electrically connected to the electrode 5, and the first conductivity type high concentration impurity region is formed. 2 is extracted by the electrode 5.

本実施形態に係るホトダイオードを示す図である。It is a figure which shows the photodiode which concerns on this embodiment. 本実施形態に係るホトダイオードに遮光膜が形成された態様を示す図である。It is a figure which shows the aspect by which the light shielding film was formed in the photodiode which concerns on this embodiment. 本実施形態に係るホトダイオードに生じる空乏層を説明するための図である。It is a figure for demonstrating the depletion layer produced in the photodiode which concerns on this embodiment. 本実施形態に係るホトダイオードアレイを示す平面図である。It is a top view which shows the photodiode array which concerns on this embodiment. 本実施形態に係る分光器を示す斜視図である。It is a perspective view which shows the spectrometer which concerns on this embodiment. 本実施形態に係るホトダイオードの第１の変形例を示す図である。It is a figure which shows the 1st modification of the photodiode which concerns on this embodiment. 本実施形態に係るホトダイオードの第２の変形例を示す図である。It is a figure which shows the 2nd modification of the photodiode which concerns on this embodiment. 本実施形態に係るホトダイオードの第３の変形例を示す図である。It is a figure which shows the 3rd modification of the photodiode which concerns on this embodiment. 本実施形態に係るホトダイオードの第４の変形例を示す図である。It is a figure which shows the 4th modification of the photodiode which concerns on this embodiment. 本実施例に係るホトダイオードに対し遮光膜が形成された場合の態様を示す平面図である。It is a top view which shows the aspect when the light shielding film is formed with respect to the photodiode which concerns on a present Example. 本実施形態に係るホトダイオードの他の変形例を示す平面図である。It is a top view which shows the other modification of the photodiode which concerns on this embodiment. 従来のホトダイオードアレイを示す平面図である。It is a top view which shows the conventional photodiode array. 従来のホトダイオードを示す平面図である。It is a top view which shows the conventional photodiode. 従来のホトダイオードに生じる空乏層を説明するための図である。It is a figure for demonstrating the depletion layer which arises in the conventional photodiode.

Explanation of symbols

１…第１導電型低濃度不純物領域、２…第１導電型高濃度不純物領域、３…第２導電型不純物層、４…シリコン熱酸化膜、５，６…電極、７…光感応領域、８…遮光膜、１０，１０ａ〜１０ｈ…ホトダイオード、２０ａ…基板、２０ｂ…シフトレジスタ、２０ｃ…読出し回路、２０ｄ…ワイヤ、２１〜２４…ホトダイオードアレイ、３０…分光器、３１・・・光ファイバ、３２…入射部、３３…回折格子部、３４…ミラー、３５…基台、３６…光検出手段。
DESCRIPTION OF SYMBOLS 1 ... 1st conductivity type low concentration impurity region, 2 ... 1st conductivity type high concentration impurity region, 3 ... 2nd conductivity type impurity layer, 4 ... Silicon thermal oxide film, 5, 6 ... Electrode, 7 ... Photosensitive region, DESCRIPTION OF SYMBOLS 8 ... Light-shielding film, 10, 10a-10h ... Photodiode, 20a ... Substrate, 20b ... Shift register, 20c ... Read-out circuit, 20d ... Wire, 21-24 ... Photodiode array, 30 ... Spectroscope, 31 ... Optical fiber, 32 ... Incident part, 33 ... Diffraction grating part, 34 ... Mirror, 35 ... Base, 36 ... Light detection means.

Claims

The planar shape of the photosensitive region where light enters is formed in a substantially rectangular shape formed by two long sides and two short sides, and the long sides forming the planar shape of the photosensitive region are arranged in parallel so as to be adjacent to each other A plurality of photodiodes, and an electrode for extracting charges generated by light incident on the photosensitive region,
The photodiode includes a first semiconductor region containing the first conductivity type impurity to constitute the photosensitive region, and the first conductivity type impurity is contained in a higher concentration than the first semiconductor region. A second semiconductor region formed by being electrically connected to the photosensitive region so as to extend in the direction of the long side forming the planar shape of the photosensitive region, and electrically connected to the electrode, A photodiode array, wherein the photodiode array is formed in a third semiconductor layer containing an impurity of a second conductivity type different from the conductivity type.

2. The photodiode array according to claim 1, wherein the photodiode is provided in the vicinity of one short side forming a planar shape of the photosensitive region. 3.

3. The photodiode array according to claim 1, wherein the second semiconductor region is formed along an outer periphery of a planar shape of the photosensitive region. 4.

A spectroscope comprising: a spectroscopic unit that splits incident light; and the photodiode array according to any one of claims 1 to 3 that converts an amount of incident light after splitting into an electric signal.