JP2009162846A - Element inspection light source, and device and method for inspecting element - Google Patents

Element inspection light source, and device and method for inspecting element Download PDF

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JP2009162846A
JP2009162846A JP2007339756A JP2007339756A JP2009162846A JP 2009162846 A JP2009162846 A JP 2009162846A JP 2007339756 A JP2007339756 A JP 2007339756A JP 2007339756 A JP2007339756 A JP 2007339756A JP 2009162846 A JP2009162846 A JP 2009162846A
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JP5157437B2 (en
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Toru Takagi
徹 高木
Satoshi Suzuki
智 鈴木
Naoki Okochi
直紀 大河内
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Nikon Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To easily estimate the focus detecting performance of an imaging element with focus detecting pixels arrayed thereon, before the imaging element is incorporated into an imaging apparatus. <P>SOLUTION: An element inspection light source 21 for inspecting the imaging element 13 where imaging pixels for imaging an image formed by an imaging optical system are two-dimensionally arrayed, and also where the plurality of focus detecting elements for detecting the focusing state of the imaging optical system are arrayed in a part thereof, and the light source 21 includes: an illumination lamp 21a; an illumination optical system 21b; and a light shielding plate 21e for limiting the luminous flux emitted from the illumination lamp 21a and transmitted through the illumination optical system 21b by a predetermined shaped aperture 21d and irradiating the focus detecting pixels on the imaging element 13 with the luminous flux. The light shielding plate 21e comprises: a first light shielding plate 21e having the first aperture 21d for generating a luminous flux equivalent to the luminous flux passing through one of a pair of areas of the exit pupil of the imaging optical system by the luminous flux transmitted through the illumination optical system 21b: and a second light shielding plate having a second aperture for generating a luminous flux equivalent to the luminous flux passing through an area other than the one area of the exit pupil by the luminous flux transmitted through the illumination optical system 21b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は素子検査用光源、素子検査装置および素子検査方法に関する。   The present invention relates to a light source for element inspection, an element inspection apparatus, and an element inspection method.

光学系により結像された像の撮像と光学系の焦点検出とを行うために、撮像画素の二次元配列の一部に焦点検出画素を配列した固体撮像素子（以下、単に撮像素子という）が知られている（例えば、特許文献１参照）。
この撮像素子は、一つの焦点検出画素の中に一対の光電変換部を設け、光学系の射出瞳の一対の領域を通過した一対の光束をマイクロレンズを介して一対の光電変換部により受光し、一対の光電変換部上に結像される一対の像のズレ量を検出して光学系の焦点調節状態を検出する、いわゆる瞳分割型位相差検出方式の焦点検出を行うために用いられる。 A solid-state imaging device (hereinafter simply referred to as an imaging device) in which focus detection pixels are arranged in a part of a two-dimensional array of imaging pixels in order to perform imaging of an image formed by the optical system and focus detection of the optical system. It is known (see, for example, Patent Document 1).
In this imaging device, a pair of photoelectric conversion units are provided in one focus detection pixel, and a pair of light beams that have passed through a pair of regions of the exit pupil of the optical system are received by the pair of photoelectric conversion units via a microlens. This is used to perform focus detection by a so-called pupil division type phase difference detection system that detects a shift amount of a pair of images formed on the pair of photoelectric conversion units and detects a focus adjustment state of the optical system.

この出願の発明に関連する先行技術文献としては次のものがある。
特開２００３−２４４７１２号公報 Prior art documents related to the invention of this application include the following.
JP 2003-244712 A

焦点検出専用の検出器と光学系を備えた従来の焦点検出装置と異なり、瞳分割型位相差検出方式の焦点検出画素を組み込んだ上記撮像素子では、焦点検出用の光学系が焦点検出画素のマイクロレンズに相当するとともに、焦点検出用の検出器が焦点検出画素の光電変換部に相当し、光学系（マイクロレンズ）と検出器（光電変換部）とが一体化している。
そのため、焦点検出画素の光電変換部や配線層の形状を変更して瞳を分割することになるが、近年の撮像素子の画素サイズは２〜１０μｍ程度であり、可視光の波長の１０倍程度の領域で分割することになるので、回折の影響や製造誤差が無視できない。
その結果、分割された瞳から所望の位相差情報が得られているかどうか定かではなく、十分な焦点検出精度が得られるかどうかは撮像装置組み込み後の実画像による評価まで判らなかった。 Unlike the conventional focus detection device having a focus detection detector and an optical system, the focus detection optical system of the focus detection pixel is the focus detection pixel in the above-described imaging element incorporating the pupil detection type phase difference detection focus detection pixel. In addition to the microlens, the focus detection detector corresponds to the photoelectric conversion unit of the focus detection pixel, and the optical system (microlens) and the detector (photoelectric conversion unit) are integrated.
For this reason, the pupil is divided by changing the shape of the photoelectric conversion unit and the wiring layer of the focus detection pixel. However, the pixel size of the recent image sensor is about 2 to 10 μm, which is about 10 times the wavelength of visible light. Therefore, the influence of diffraction and manufacturing errors cannot be ignored.
As a result, it is not certain whether the desired phase difference information is obtained from the divided pupils, and it has not been known until evaluation with an actual image after incorporating the imaging device whether sufficient focus detection accuracy is obtained.

（１） 請求項１の発明は、撮像光学系により結像された像を撮像するための撮像画素が二次元配列された撮像素子の一部に、撮像光学系の焦点調節状態を検出するための焦点検出画素を複数個配列した撮像素子を検査する素子検査用光源であって、照明灯と、照明光学系と、照明灯から発せられ照明光学系を透過した光束を、所定形状の開口により制限して撮像素子上の焦点検出画素に照射する遮光板とを備え、遮光板は、撮像光学系の射出瞳の一対の領域の内の一方の領域を通過する光束と同等な光束を照明光学系を透過した光束より生成する第１開口を有する第１遮光板と、射出瞳の一方の領域以外の領域を通過する光束と同等な光束を照明光学系を透過した光束より生成する第２開口を有する第２遮光板とからなる。
（２） 請求項２の発明は、請求項１に記載の素子検査用光源において、第１開口を射出瞳を二等分した一方の領域に相当する開口とし、第２開口を射出瞳を二等分した他方の領域に相当する開口としたものである。
（３） 請求項３の発明は、請求項１または請求項２に記載の素子検査用光源において、遮光板の照明灯側に光を拡散させるための拡散板を設置したものである。
（４） 請求項４の発明は、請求項１〜３のいずれか一項に記載の素子検査用光源において、遮光板を回転させる駆動手段を備え、光学系の射出瞳の一対の領域の内の一方の領域を通過する光束を焦点検出用光束として受光する焦点検出画素を検査する場合と、一対の領域の内の他方の領域を通過する光束を焦点検出用光束として受光する焦点検出画素を検査する場合とで、駆動手段により遮光板を１８０度回転させるようにしたものである。
（５） 請求項５の発明は、請求項１〜４のいずれか一項に記載の検査用光源と、第１遮光板を用いて焦点検出画素を照射した場合の焦点検出画素の出力信号Ｓと、第２遮光板を用いて焦点検出画素を照射した場合の焦点検出画素の出力信号Ｎとを測定する測定手段と、出力信号Ｓと出力信号Ｎとに基づいて撮像素子の焦点検出性能を判定する判定手段とを備える素子検査装置である。
（６） 請求項６の発明は、請求項５に記載の素子検査装置において、判定手段は、撮像素子の中に出力信号Ｓと出力信号Ｎの比Ｓ／Ｎが予め設定した判定基準値以下の焦点検出画素が含まれていた場合には、当該撮像素子を不良品と判定するようにしたものである。
（７） 請求項７の発明は、撮像光学系により結像された像を撮像するための撮像画素が二次元配列された撮像素子の一部に、撮像光学系の焦点調節状態を検出するための焦点検出画素を複数個配列した撮像素子を検査する素子検査方法であって、照明灯から発せられ照明光学系を透過した光束を、所定形状の開口により制限して撮像素子上の焦点検出画素に照射する際に、撮像光学系の射出瞳の一対の領域の内の一方の領域を通過する光束と同等な光束を照明光学系を透過した光束より生成する第１開口により光束を制限して焦点検出画素を照射した場合の焦点検出画素の出力信号Ｓと、射出瞳の一方の領域以外の領域を通過する光束と同等な光束を照明光学系を透過した光束より生成する第２開口により光束を制限して焦点検出画素を照射した場合の焦点検出画素の出力信号Ｎとを測定し、出力信号Ｓと出力信号Ｎの比Ｓ／Ｎに基づいて撮像素子の焦点検出性能を評価する素子検査方法である。 (1) In order to detect the focus adjustment state of the imaging optical system in a part of the imaging element in which imaging pixels for imaging an image formed by the imaging optical system are two-dimensionally arranged. A light source for inspecting an image pickup device in which a plurality of focus detection pixels are arranged, and an illumination lamp, an illumination optical system, and a light beam emitted from the illumination lamp and transmitted through the illumination optical system through an aperture having a predetermined shape A light-blocking plate that irradiates the focus detection pixels on the image sensor in a limited manner, and the light-blocking plate illuminates a light beam equivalent to a light beam that passes through one of the pair of regions of the exit pupil of the imaging optical system. A first light-shielding plate having a first aperture generated from a light beam transmitted through the system, and a second aperture for generating a light beam equivalent to a light beam passing through a region other than one region of the exit pupil from the light beam transmitted through the illumination optical system A second light-shielding plate having
(2) According to a second aspect of the present invention, in the element inspection light source according to the first aspect, the first opening is an opening corresponding to one region obtained by dividing the exit pupil into two equal parts, and the second opening is the second exit pupil. This is an opening corresponding to the other equally divided region.
(3) The invention of claim 3 is the element inspection light source according to claim 1 or 2, wherein a diffusion plate for diffusing light is installed on the side of the illuminating lamp of the light shielding plate.
(4) The invention according to claim 4 is the element inspection light source according to any one of claims 1 to 3, further comprising a driving unit that rotates the light shielding plate, and includes a pair of regions of the exit pupil of the optical system. A focus detection pixel that receives a light beam that passes through one of the two regions as a focus detection light beam, and a focus detection pixel that receives a light beam that passes through the other region of the pair of regions as a focus detection light beam. In the case of inspection, the light shielding plate is rotated 180 degrees by the driving means.
(5) The invention according to claim 5 is the output signal S of the focus detection pixel when the focus detection pixel is irradiated using the inspection light source according to any one of claims 1 to 4 and the first light shielding plate. Measuring means for measuring the output signal N of the focus detection pixel when the focus detection pixel is irradiated using the second light shielding plate, and the focus detection performance of the image sensor based on the output signal S and the output signal N. It is an element inspection apparatus provided with the determination means to determine.
(6) In the element inspection apparatus according to claim 5, the determination unit is configured such that the determination unit has a ratio S / N of the output signal S and the output signal N in the imaging element equal to or less than a predetermined determination reference value. If this focus detection pixel is included, the image sensor is determined to be defective.
(7) The invention of claim 7 is for detecting the focus adjustment state of the imaging optical system in a part of the imaging element in which imaging pixels for imaging an image formed by the imaging optical system are two-dimensionally arranged. Inspection method for inspecting an image pickup device in which a plurality of focus detection pixels are arranged, wherein a light beam emitted from an illumination lamp and transmitted through an illumination optical system is limited by an aperture having a predetermined shape, and the focus detection pixel on the image pickup device When the light beam is irradiated, the light beam is limited by a first aperture that generates a light beam equivalent to a light beam passing through one of the pair of areas of the exit pupil of the imaging optical system from the light beam transmitted through the illumination optical system. The output signal S of the focus detection pixel when the focus detection pixel is irradiated and the second aperture which generates a light beam equivalent to the light beam passing through the region other than one region of the exit pupil from the light beam transmitted through the illumination optical system The focus detection pixels In this case, the output signal N of the focus detection pixel is measured, and the focus detection performance of the image sensor is evaluated based on the ratio S / N between the output signal S and the output signal N.

本発明によれば、焦点検出画素が配列された撮像素子の焦点検出性能を、撮像素子を撮像装置に組み込む前に簡単に評価することができる。   According to the present invention, it is possible to easily evaluate the focus detection performance of an image pickup device in which focus detection pixels are arranged before the image pickup device is incorporated into an image pickup apparatus.

まず、瞳分割型位相差検出方式の焦点検出画素が組み込まれた撮像素子の特性を評価するための指標について説明する。ここで、撮像素子の受光面に像を結像する撮像光学系の射出瞳を想定する。焦点検出画素の光電変換部は、射出瞳の一方の領域を通過する光束を受光するためにマイクロレンズの一方側に偏って配置される（図４参照）。この瞳面の分割した一対の領域の内の一方の領域からの入射光を受光したときの焦点検出画素の出力信号（位相情報）をＳとし、上記一方の領域以外の領域（ここには一対の領域の内の他方の領域も含まれる）からの入射光を受光したときの出力信号をＮとする。後者の出力信号Ｎは、光束の回折や乱反射、あるいは製造誤差等に起因したものであり、前記一方の領域以外の領域から入射した光に応じた出力信号である。二つの出力信号ＳとＮの比Ｓ／Ｎは焦点検出画素の焦点検出性能を表すものであり、この比Ｓ／Ｎが大きいほど撮像素子上の焦点検出画素の出力信号Ｓに基づく焦点検出結果は良好なものとなる。したがって、この比Ｓ／Ｎを焦点検出画素の焦点検出性能を示す指標とする。   First, an index for evaluating the characteristics of an image sensor incorporating a focus detection pixel of the pupil division type phase difference detection method will be described. Here, an exit pupil of an imaging optical system that forms an image on the light receiving surface of the imaging element is assumed. The photoelectric conversion unit of the focus detection pixel is arranged so as to be biased toward one side of the microlens in order to receive a light beam passing through one region of the exit pupil (see FIG. 4). The output signal (phase information) of the focus detection pixel when receiving incident light from one of the pair of divided areas of the pupil plane is S, and an area other than the one area (here, a pair of areas) The output signal when the incident light from the other region is also received is N. The latter output signal N is caused by diffraction or irregular reflection of a light beam, a manufacturing error, or the like, and is an output signal corresponding to light incident from a region other than the one region. The ratio S / N between the two output signals S and N represents the focus detection performance of the focus detection pixel, and the focus detection result based on the output signal S of the focus detection pixel on the image sensor as the ratio S / N increases. Will be good. Therefore, this ratio S / N is used as an index indicating the focus detection performance of the focus detection pixel.

射出瞳面における一対の領域は、横方向の焦点検出の場合は左右に分割し、縦方向の焦点検出の場合は上下に分割する。そして、一対の領域からの一対の光束に対応した一対の位相情報を取得し、この一対の位相情報の位相差に基づいて焦点検出を行う。ここで、瞳上の一対の領域をＲ１、Ｒ２とし、一対の光束をＰ１、Ｐ２とすると、一方の領域Ｒ１からの光束Ｐ１に応じた出力信号Ｓと、一方の領域Ｒ１以外の領域Ｒ１’からの光束Ｐ１’に応じた出力信号Ｎとの比Ｓ／Ｎ１は、一方の領域Ｒ１からの光束Ｐ１を受光する焦点検出画素の性能を示す。同様に、一対の領域Ｒ１、Ｒ２の内の他方の領域Ｒ２からの光束Ｐ２に応じた出力信号Ｓと、他方の領域Ｒ２以外の領域Ｒ２’からの光束Ｐ２’に応じた出力信号Ｎとの比Ｓ／Ｎ２は、他方の領域Ｒ２からの光束Ｐ２を受光する焦点検出画素の性能を表す。   The pair of regions on the exit pupil plane are divided into left and right in the case of horizontal focus detection, and up and down in the case of vertical focus detection. Then, a pair of phase information corresponding to the pair of light beams from the pair of regions is acquired, and focus detection is performed based on the phase difference between the pair of phase information. Here, if the pair of regions on the pupil are R1 and R2, and the pair of light beams are P1 and P2, the output signal S corresponding to the light beam P1 from one region R1 and the region R1 ′ other than the one region R1. The ratio S / N1 with the output signal N corresponding to the light beam P1 ′ from the light indicates the performance of the focus detection pixel that receives the light beam P1 from one region R1. Similarly, an output signal S corresponding to the light beam P2 from the other region R2 of the pair of regions R1 and R2, and an output signal N corresponding to the light beam P2 ′ from the region R2 ′ other than the other region R2. The ratio S / N2 represents the performance of the focus detection pixel that receives the light beam P2 from the other region R2.

この一実施の形態では、一対の瞳領域Ｒ１、Ｒ２からの光束Ｐ１、Ｐ２を受光する焦点検出画素の性能をＳ／Ｎ１、Ｓ／Ｎ２で表し、焦点検出画素配列の中の最も小さい比Ｓ／Ｎを撮像素子の焦点検出性能指標とする。撮像素子を装置に組み込む前の撮像素子の検査工程において、撮像素子単体の焦点検出性能Ｓ／Ｎを測定することによって、事前に撮像素子の良否を判定することができ、良品だけを素子込み込み工程へ流すことができる。なお、ここでは焦点検出画素が１つの光電変換部を有するものとして説明するが、このような焦点検出画素に限定されない。例えば、焦点検出画素は２つの光電変換部を有してもよい（図１４参照）。この種の焦点検出画素については後述する。   In this embodiment, the performance of the focus detection pixels that receive the light beams P1 and P2 from the pair of pupil regions R1 and R2 is represented by S / N1 and S / N2, and the smallest ratio S in the focus detection pixel array. Let / N be the focus detection performance index of the image sensor. By measuring the focus detection performance S / N of a single image sensor in the image sensor inspection process before incorporating the image sensor into the device, the quality of the image sensor can be determined in advance, and only good products are included. It can flow to the process. Here, the focus detection pixel is described as having one photoelectric conversion unit, but is not limited to such a focus detection pixel. For example, the focus detection pixel may have two photoelectric conversion units (see FIG. 14). This type of focus detection pixel will be described later.

撮像素子の焦点検出性能評価においては、上述した焦点検出光学系による要因以外に、焦点検出画素からの出力自体を電気回路系統のノイズより十分に大きくする必要があり、焦点検出画素からの出力の大きさも性能評価の対象となる。   In the focus detection performance evaluation of the image sensor, in addition to the above-described factors due to the focus detection optical system, the output from the focus detection pixel itself needs to be sufficiently larger than the noise of the electric circuit system. Size is also subject to performance evaluation.

さらに具体的な検査方法について説明する。この一実施の形態では、撮像光学系の射出瞳を分割した一対の領域Ｒ１、Ｒ２の内の一方の領域Ｒ１と同形状の光源と、上記一方の領域Ｒ１以外の領域Ｒ１’（ここには一対の領域の内の他方の領域Ｒ２も含まれる）と同形状の光源とを用い、上述した出力信号ＳとＮを個別に測定する。   Further, a specific inspection method will be described. In this embodiment, a light source having the same shape as one region R1 out of a pair of regions R1 and R2 obtained by dividing the exit pupil of the imaging optical system, and a region R1 ′ other than the one region R1 (here, The output signals S and N described above are individually measured using a light source having the same shape as the other region R2 of the pair of regions).

領域Ｒ１に対応する光源は、一般的にウエハーから切り出す前の撮像素子単体の特性評価時に使用する白色光源と絞りからなる。絞りは白色光源と撮像素子の間の、撮像素子から撮像光学系の射出瞳距離だけ離れた位置に設置される一対の領域Ｒ１、Ｒ２の内の一方の領域Ｒ１の形状を有している。その絞りより白色光源側に拡散板が設置され、一方の領域Ｒ１に均一光が照射される。   The light source corresponding to the region R1 is generally composed of a white light source and a diaphragm used when evaluating the characteristics of the image pickup device before being cut out from the wafer. The diaphragm has the shape of one region R1 out of a pair of regions R1 and R2 that are installed between the white light source and the image sensor at a position separated from the image sensor by the exit pupil distance of the image pickup optical system. A diffusion plate is installed on the white light source side of the diaphragm, and uniform light is irradiated to one region R1.

さらに、一方の領域Ｒ１以外の領域Ｒ１’に対応する光源には、上記一方の領域Ｒ１の形状の絞りの代わりに、射出瞳面の一方の領域Ｒ１を補間する形状と同形状の絞りを設置すればよい。このような絞りと拡散板を白色光源と撮像素子との間に設定することによって、容易に撮像素子の焦点検出性能を評価することができる。   Furthermore, the light source corresponding to the region R1 ′ other than the one region R1 is provided with a diaphragm having the same shape as the shape for interpolating one region R1 of the exit pupil plane instead of the diaphragm having the shape of the one region R1. do it. By setting such a diaphragm and a diffusion plate between the white light source and the image sensor, the focus detection performance of the image sensor can be easily evaluated.

図１は検査対象の撮像素子の一例で光電変換部を正面から見た部分拡大図である。この撮像素子１は、撮像光学系（不図示）により結像された像を撮像するための撮像画素２が半導体基板６上に二次元状に配列されており、その一部に撮像画素２の代わりに撮像光学系の焦点調節状態を検出するための２種類の焦点検出画素３ａと３ｂが直線上に交互に配列されている。   FIG. 1 is a partially enlarged view of an example of an image sensor to be inspected, as viewed from the front of a photoelectric conversion unit. In this imaging device 1, imaging pixels 2 for imaging an image formed by an imaging optical system (not shown) are two-dimensionally arranged on a semiconductor substrate 6. Instead, two types of focus detection pixels 3a and 3b for detecting the focus adjustment state of the imaging optical system are alternately arranged on a straight line.

図２は撮像画素２の正面図、図３は撮像画素２の断面図である。撮像画素２は被写体を画像化するための信号を出力する。撮像画素２はマイクロレンズ４、光電変換部５および色フィルター（不図示）を有している。その他の構成は省略されている。色フィルターは赤（Ｒ）、緑（Ｇ）、青（Ｂ）の３種類からなり、各色フィルターを備えた撮像画素２がベイヤー配列されている。撮像画素２では撮像用の光電変換部５の前方にマイクロレンズ４が配置される。光電変換部５は半導体回路基板６上に形成される。なお、不図示の色フィルターはマイクロレンズ４と光電変換部５の中間に配置される。   FIG. 2 is a front view of the imaging pixel 2, and FIG. 3 is a cross-sectional view of the imaging pixel 2. The imaging pixel 2 outputs a signal for imaging the subject. The imaging pixel 2 includes a microlens 4, a photoelectric conversion unit 5, and a color filter (not shown). Other configurations are omitted. There are three types of color filters, red (R), green (G), and blue (B), and image pickup pixels 2 having each color filter are arranged in a Bayer array. In the imaging pixel 2, the microlens 4 is disposed in front of the photoelectric conversion unit 5 for imaging. The photoelectric conversion unit 5 is formed on the semiconductor circuit substrate 6. A color filter (not shown) is arranged between the microlens 4 and the photoelectric conversion unit 5.

図４は焦点検出画素３ａ、３ｂの正面図、図５は焦点検出画素３ａ、３ｂの断面図である。焦点検出画素３ａは、図４(ａ)に示すようにマイクロレンズ４と光電変換部７を有している。光電変換部７の形状は矩形である。同様に、焦点検出画素３ｂは、図４(ｂ)に示すようにマイクロレンズ４と光電変換部８を有しており、光電変換部８の形状は矩形である。なお、焦点検出画素３ａ、３ｂのその他の構成は省略されている。この実施の形態では、光電変換部７，８の画素中心側の境界が画素中心と一致するように設計されている。焦点検出画素３ａと焦点検出画素３ｂとをマイクロレンズ４を重ね合わせて表示すると、光電変換部７と８が左右方向に並んでいる。図１において、焦点検出画素３ａと焦点検出画素３ｂは左右方向、すなわち光電変換部７と８の並び方向に交互に配置されている。   4 is a front view of the focus detection pixels 3a and 3b, and FIG. 5 is a cross-sectional view of the focus detection pixels 3a and 3b. The focus detection pixel 3a includes a microlens 4 and a photoelectric conversion unit 7 as shown in FIG. The shape of the photoelectric conversion unit 7 is a rectangle. Similarly, the focus detection pixel 3b includes a microlens 4 and a photoelectric conversion unit 8 as shown in FIG. 4B, and the photoelectric conversion unit 8 has a rectangular shape. Note that other configurations of the focus detection pixels 3a and 3b are omitted. In this embodiment, the photoelectric conversion units 7 and 8 are designed so that the boundary on the pixel center side coincides with the pixel center. When the focus detection pixel 3a and the focus detection pixel 3b are displayed with the microlens 4 superimposed, the photoelectric conversion units 7 and 8 are arranged in the left-right direction. In FIG. 1, the focus detection pixels 3 a and the focus detection pixels 3 b are alternately arranged in the left-right direction, that is, the arrangement direction of the photoelectric conversion units 7 and 8.

図５(ａ)に示すように、焦点検出画素３ａの光電変換部７の前方にマイクロレンズ４が配置される。光電変換部７は半導体回路基板６上に形成されるとともに、その上にマイクロレンズ４が半導体イメージセンサーの製造工程により一体的かつ固定的に形成される。同様に、図５(ｂ)に示すように、焦点検出画素３ｂの光電変換部８の前方にマイクロレンズ４が配置され、マイクロレンズ４により光電変換部８の形状が前方に投影される。光電変換部８は半導体回路基板６上に形成されるとともに、その上にマイクロレンズ４が半導体イメージセンサーの製造工程により一体的かつ固定的に形成される。   As shown in FIG. 5A, the micro lens 4 is disposed in front of the photoelectric conversion unit 7 of the focus detection pixel 3a. The photoelectric conversion unit 7 is formed on the semiconductor circuit substrate 6, and the microlens 4 is integrally and fixedly formed thereon by a semiconductor image sensor manufacturing process. Similarly, as shown in FIG. 5B, the microlens 4 is disposed in front of the photoelectric conversion unit 8 of the focus detection pixel 3b, and the shape of the photoelectric conversion unit 8 is projected forward by the microlens 4. The photoelectric conversion unit 8 is formed on the semiconductor circuit substrate 6, and the microlens 4 is integrally and fixedly formed on the photoelectric conversion unit 8 by a manufacturing process of the semiconductor image sensor.

図６(ａ)は、撮像素子上の焦点検出画素３ａ（または３ｂ）と撮像光学系の射出瞳１０との関係を示す図である。ここでは、焦点検出画素３ａのマイクロレンズ４から１００mmの位置に撮像光学系の射出瞳１０があるものとし、瞳の明るさをｆ２．８とする。焦点検出画素３ａの光電変換面１１上の破線１０ａは、図６(ｂ)に示すようにマイクロレンズ４による射出瞳１０の投影像である。なお、図６では説明を解りやすくするためにマイクロレンズ４と光電変換部７（または８）からなる焦点検出画素３ａを撮像光学系と同程度の大きさで示しているが、実際には撮像光学系の１／１００００程度の大きさである。   FIG. 6A is a diagram illustrating the relationship between the focus detection pixel 3a (or 3b) on the image sensor and the exit pupil 10 of the imaging optical system. Here, it is assumed that the exit pupil 10 of the imaging optical system is located 100 mm from the micro lens 4 of the focus detection pixel 3a, and the brightness of the pupil is f2.8. A broken line 10a on the photoelectric conversion surface 11 of the focus detection pixel 3a is a projection image of the exit pupil 10 by the microlens 4 as shown in FIG. In FIG. 6, the focus detection pixel 3a including the microlens 4 and the photoelectric conversion unit 7 (or 8) is shown in the same size as the imaging optical system for easy understanding, but in practice, the imaging is performed. The size is about 1/10000 of the optical system.

図６において、理想的な焦点検出光学系であれば、ｆ２．８の明るさの射出瞳１０の半分の領域を通過した焦点検出用光束が光電変換部７（または８）に入射し、光電変換部７で光強度に応じた電気信号に変換される。射出瞳１０の残りの半分の領域を通過した光束は光電変換部７以外の領域に入射するので、光電変換部７の出力信号にはまったく寄与しない。しかしながら、実際には、マイクロレンズ４の設計との乖離や回折の影響から、焦点検出用光束の一部が光電変換部７へ入射せずに光電変換部以外の領域へ入射し、射出瞳１０の残り半分の領域を通過した光束の一部が光電変換部７へ入射する。   In FIG. 6, in the case of an ideal focus detection optical system, a focus detection light beam that has passed through a half region of the exit pupil 10 having a brightness of f2.8 is incident on the photoelectric conversion unit 7 (or 8), The signal is converted into an electrical signal corresponding to the light intensity by the converter 7. Since the light beam that has passed through the remaining half of the exit pupil 10 enters the region other than the photoelectric conversion unit 7, it does not contribute to the output signal of the photoelectric conversion unit 7 at all. However, in reality, due to the deviation from the design of the microlens 4 and the influence of diffraction, a part of the focus detection light beam does not enter the photoelectric conversion unit 7 but enters the region other than the photoelectric conversion unit, and the exit pupil 10 Part of the light beam that has passed through the remaining half of the light enters the photoelectric conversion unit 7.

図７は、射出瞳１０の左半分の領域１０ｂを通過した光束（焦点検出画素３ｂが焦点検出に用いる光束）が、焦点検出画素３ｂのマイクロレンズ４を介して光電変換面１１へ入射する様子を示す。射出瞳１０の領域１０ｂを通過した光束は、理想的には焦点検出画素３ｂの光電変換部８へ入射するはずであるが、上述した問題によりこの光束は光電変換面１１上の領域１０ｃへ入射し、光電変換部８以外の領域に漏れ出してしまう。   FIG. 7 shows a state in which the light beam that has passed through the left half region 10b of the exit pupil 10 (the light beam used by the focus detection pixel 3b for focus detection) enters the photoelectric conversion surface 11 via the microlens 4 of the focus detection pixel 3b. Indicates. The light beam that has passed through the region 10b of the exit pupil 10 should ideally be incident on the photoelectric conversion unit 8 of the focus detection pixel 3b. However, due to the above-described problem, this light beam is incident on the region 10c on the photoelectric conversion surface 11. As a result, it leaks into a region other than the photoelectric conversion unit 8.

図８は、射出瞳１０の残り半分の領域１０ｄを通過した光束（焦点検出画素３ｂが焦点検出に用いない光束）が、焦点検出画素３ｂのマイクロレンズ４を介して光電変換面１１へ入射する様子を示す。射出瞳１０の残り半分の領域１０ｄを通過した光束は、理想的には焦点検出画素３ｂの光電変換部８以外の領域へ入射するはずであるが、上述した問題によりこの光束は光電変換面１１上の領域１０ｅへ入射し、光電変換部８へ漏れ込んでしまう。   In FIG. 8, the light beam that has passed through the remaining half region 10d of the exit pupil 10 (the light beam that the focus detection pixel 3b does not use for focus detection) enters the photoelectric conversion surface 11 via the microlens 4 of the focus detection pixel 3b. Show the state. The light beam that has passed through the remaining half region 10d of the exit pupil 10 should ideally be incident on a region other than the photoelectric conversion unit 8 of the focus detection pixel 3b. The light enters the upper region 10 e and leaks into the photoelectric conversion unit 8.

なお、図７および図８では、右側に光電変換部８を有する焦点検出画素３ｂを例に挙げて説明したが、左側に光電変換部７を有する焦点検出画素３ａについても同様な光束の漏れ出しと漏れ込みが発生する。この焦点検出画素３ａにおいては、射出瞳１０の光束を通過する領域を入れ替えるだけであり、図示と説明を省略する。なお、焦点検出画素３ａの光電変換部７は、図８に示す射出瞳１０の右半分の領域１０ｄを通過した光束を焦点検出用光束として受光する。   7 and 8, the focus detection pixel 3b having the photoelectric conversion unit 8 on the right side is described as an example. However, similar leakage of the light flux is performed on the focus detection pixel 3a having the photoelectric conversion unit 7 on the left side. Leakage occurs. In this focus detection pixel 3a, only the region of the exit pupil 10 through which the light flux passes is replaced, and illustration and description thereof are omitted. The photoelectric conversion unit 7 of the focus detection pixel 3a receives the light beam that has passed through the right half region 10d of the exit pupil 10 shown in FIG. 8 as a focus detection light beam.

焦点検出画素３ｂの光電変換部８は、図７に示す射出瞳１０の左半分の領域１０ｂを通過した光束と、図８に示す射出瞳１０の右半分の領域１０ｄを通過した光束の一部とを受光し、受光光束の光強度に応じた信号を出力する。一方、焦点検出画素３ａの光電変換部７は、図８に示す射出瞳１０の右半分の領域１０ｄを通過した光束と、図７に示す射出瞳１０の左半分の領域１０ｂを通過した光束の一部とを受光し、受光光束の光強度に応じた信号を出力する。これら焦点検出画素３ａと３ｂの出力信号は、撮像光学系の焦点調節状態を示す一対の位相情報となる。   The photoelectric conversion unit 8 of the focus detection pixel 3b has a part of the light beam that has passed through the left half region 10b of the exit pupil 10 illustrated in FIG. 7 and a part of the light beam that has passed through the right half region 10d of the exit pupil 10 illustrated in FIG. And outputs a signal corresponding to the light intensity of the received light flux. On the other hand, the photoelectric conversion unit 7 of the focus detection pixel 3a has a light flux that has passed through the right half area 10d of the exit pupil 10 shown in FIG. 8 and a light flux that has passed through the left half area 10b of the exit pupil 10 shown in FIG. A part of the light is received and a signal corresponding to the light intensity of the received light beam is output. The output signals of these focus detection pixels 3a and 3b become a pair of phase information indicating the focus adjustment state of the imaging optical system.

射出瞳１０の左半分の領域１０ｂと右半分の領域１０ｄをそれぞれ通過した光束によって焦点検出用の位相差情報を正確に検出するためには、焦点検出画素３ｂでは、図７に示す左半分の領域１０ｂからの光束をより多く受光し（つまり、光束が光電変換部８以外へ漏れ出さないようにし）、図８に示す右半分の領域１０ｄからの光束をより少なく受光する（つまり、光束が光電変換部８へ漏れ込まないようにする）ことが重要になる。一方、焦点検出画素３ａでは、図７に示す左半分の領域１０ｂからの光束をより少なく受光し（光束が光電変換部７へ漏れ込まないようにし）、図８に示す右半分の領域１０ｄからの光束をより多く受光する（光束が光電変換部７以外へ漏れ出さないようにする）ことが重要になる。   In order to accurately detect the phase difference information for focus detection using the light beams that have passed through the left half area 10b and the right half area 10d of the exit pupil 10, the focus detection pixel 3b has the left half area shown in FIG. More light flux from the region 10b is received (that is, the light flux does not leak to other than the photoelectric conversion unit 8), and less light flux is received from the right half region 10d shown in FIG. It is important that it does not leak into the photoelectric conversion unit 8). On the other hand, the focus detection pixel 3a receives a smaller amount of light from the left half region 10b shown in FIG. 7 (so that the light does not leak into the photoelectric conversion unit 7), and from the right half region 10d shown in FIG. It is important to receive a larger amount of the light beam (to prevent the light beam from leaking to other than the photoelectric conversion unit 7).

焦点検出画素３ｂにおいて、図７に示す左半分の領域１０ｂからの光束による焦点検出画素３ｂの出力信号をＳとし、図８に示す右半分の領域１０ｄからの光束による焦点検出画素３ｂの出力信号をＮとすると、上述したように比Ｓ／Ｎは位相差情報の正確さを表すパラメーターであり、焦点検出画素３ｂの焦点検出性能を示す指標値とすることができる。一方、焦点検出画素３ａでは、図８に示す右半分の領域１０ｄからの光束による焦点検出画素３ａの出力信号をＳとし、図７に示す左半分の領域１０ｂからの光束による焦点検出画素３ａの出力信号をＮとすると、比Ｓ／Ｎは位相差情報の正確さを表すパラメーターであり、焦点検出画素３ａの焦点検出性能を示す指標値とすることができる。   In the focus detection pixel 3b, the output signal of the focus detection pixel 3b by the light beam from the left half region 10b shown in FIG. 7 is S, and the output signal of the focus detection pixel 3b by the light beam from the right half region 10d shown in FIG. Assuming that N is N, the ratio S / N is a parameter indicating the accuracy of the phase difference information as described above, and can be an index value indicating the focus detection performance of the focus detection pixel 3b. On the other hand, in the focus detection pixel 3a, the output signal of the focus detection pixel 3a by the light beam from the right half region 10d shown in FIG. 8 is set as S, and the focus detection pixel 3a by the light beam from the left half region 10b shown in FIG. When the output signal is N, the ratio S / N is a parameter indicating the accuracy of the phase difference information, and can be an index value indicating the focus detection performance of the focus detection pixel 3a.

ここで、図９を参照してシリコンウエハー上に形成された撮像素子の一般的な検査方法を説明する。ステージ（不図示）上のシリコンウエハー１２には複数の固体撮像素子１３が形成されており、撮像素子１３と同じ大きさの開口（不図示）を有するプローブカード（不図示）がウエハー１２上にセットされ、プローブカードと撮像素子１３とが電気的に接続されるとともに、ランプ１５と照明光学系１６からなる検査用光源１７からの光をプローブカードの開口を介して撮像素子１３に照射する。なお、図９では説明を解りやすくするためにプローブカードの下に位置するウエハー１２が見えるように図示したが、実際のプローブカードは開口以外の部分は不透明である。一つの撮像素子１３の検査が終了すると、ステージが移動して次の撮像素子１３がプローブカードの開口の真下にセットされ、これを繰り返してウエハー１２上のすべての撮像素子１３の検査が行われる。   Here, a general inspection method for an image sensor formed on a silicon wafer will be described with reference to FIG. A plurality of solid-state imaging devices 13 are formed on a silicon wafer 12 on a stage (not shown), and a probe card (not shown) having an opening (not shown) having the same size as the imaging device 13 is formed on the wafer 12. The probe card and the image sensor 13 are electrically connected, and light from the inspection light source 17 including the lamp 15 and the illumination optical system 16 is irradiated to the image sensor 13 through the opening of the probe card. In FIG. 9, for ease of explanation, the wafer 12 positioned under the probe card is shown to be visible, but the actual probe card is opaque except for the opening. When the inspection of one image sensor 13 is completed, the stage moves and the next image sensor 13 is set immediately below the opening of the probe card, and this is repeated to inspect all the image sensors 13 on the wafer 12. .

次に、焦点検出性能指標Ｓ／Ｎの具体的な測定装置と測定方法を説明する。図１０は一実施の形態の素子検査装置の構成を示す図である。瞳分割型位相差検出方式による焦点検出画素を組み込んだ撮像素子の検査装置２０は、検査用光源２１、ウエハープローバー２２およびテスター２３から構成される。検査用光源２１は、図７に示すように射出瞳１０の左半分の領域１０ｂを通過して焦点検出画素３ｂに向かう光束を生成するとともに、図８に示すように射出瞳１０の右半分の領域１０ｄを通過して焦点検出画素３ｂに向かう光束を生成する。   Next, a specific measuring apparatus and measuring method for the focus detection performance index S / N will be described. FIG. 10 is a diagram illustrating a configuration of an element inspection apparatus according to an embodiment. An imaging device inspection apparatus 20 incorporating a focus detection pixel by a pupil division type phase difference detection system includes an inspection light source 21, a wafer prober 22, and a tester 23. As shown in FIG. 7, the inspection light source 21 generates a light beam that passes through the left half region 10b of the exit pupil 10 and travels toward the focus detection pixel 3b, and at the right half of the exit pupil 10 as shown in FIG. A light flux that passes through the region 10d and travels toward the focus detection pixel 3b is generated.

ウエハープローバー２２は、ウエハー１２の搬送、ウエハー１２上の撮像素子１３とテスター２３との電気的な接続などを行う装置であり、例えば東京エレクトロン株式会社製Ｐ−８ＸＬ型などを用いることができる。さらに、テスター２３は、ウエハー１２上の撮像素子１３をウエハープローバー２２を介して駆動制御し、撮像素子１３からの出力信号を測定して撮像素子１３上の撮像画素２の撮像性能や焦点検出画素３ａ、３ｂの焦点検出性能を評価する。テスター２３はまた、詳細を後述する検査用光源２１のランプの点消灯制御と、拡散板と遮光板の照明光路への出し入れおよび回転を制御する。テスター２３には例えば株式会社アドバンテスト製Ｔ８５７１Ａ型などを用いることができる。   The wafer prober 22 is a device for carrying the wafer 12, electrically connecting the image sensor 13 on the wafer 12 and the tester 23, and for example, a P-8XL type manufactured by Tokyo Electron Ltd. can be used. Further, the tester 23 drives and controls the image sensor 13 on the wafer 12 via the wafer prober 22, measures the output signal from the image sensor 13, and the imaging performance and focus detection pixel of the image pixel 2 on the image sensor 13. The focus detection performance of 3a and 3b is evaluated. The tester 23 also controls turning on / off of the lamp of the inspection light source 21, which will be described in detail later, and controlling the movement of the diffusion plate and the light shielding plate into and out of the illumination optical path. As the tester 23, for example, T8571A manufactured by Advantest Co., Ltd. can be used.

図１１は検査用光源２１の詳細な構成を示す斜視図であり、図１２は検査用光源２１の一部と撮像素子１３上の焦点検出画素３ｂの横断面図である。なお、図１２では焦点検出画素３ｂの断面を示すが、焦点検出画素３ａについても同様である。検査用光源２１は、ランプ２１ａ、照明光学系２１ｂ、ランプ２１ａからの光を拡散させる拡散板２１ｃ、開口２１ｄを有する遮光板２１ｅ、遮光板２１ｅの出し入れと回転を行う駆動装置２１ｆなどを備えている。   FIG. 11 is a perspective view showing a detailed configuration of the inspection light source 21, and FIG. 12 is a cross-sectional view of a part of the inspection light source 21 and the focus detection pixel 3 b on the image sensor 13. FIG. 12 shows a cross section of the focus detection pixel 3b, but the same applies to the focus detection pixel 3a. The inspection light source 21 includes a lamp 21a, an illumination optical system 21b, a diffusion plate 21c for diffusing the light from the lamp 21a, a light shielding plate 21e having an opening 21d, a drive device 21f for taking in and out the light shielding plate 21e, and the like. Yes.

図９により説明した一般的な撮像素子の検査装置の検査用光源１７と異なるのは、一実施の形態の検査用光源２１が、照明光学系２１ｂとウエハープローバー２２のプローブカード（不図示）との間に、拡散板２１ｃと開口２１ｄを有する遮光板２１ｅを出し入れ可能に設置したことにある。この拡散板２１ｃと遮光板２１ｅは、ウエハー１２上の撮像素子１３から撮像光学系の射出瞳距離相当の距離１００ｍｍだけ離れた位置に挿入される。拡散板２１ｃと遮光板２１ｅは貼り合わせて一体に形成されており、開口２１ｄはｆ２．８の明るさの射出瞳の半分の大きさである。遮光板２１ｅの開口２１ｄ以外の部分は光を完全に遮光する。   Unlike the inspection light source 17 of the general image sensor inspection apparatus described with reference to FIG. 9, the inspection light source 21 according to the embodiment includes an illumination optical system 21b and a probe card (not shown) of the wafer prober 22. The light shielding plate 21e having the diffusion plate 21c and the opening 21d is installed so as to be able to be taken in and out. The diffusing plate 21c and the light shielding plate 21e are inserted at a position away from the imaging element 13 on the wafer 12 by a distance of 100 mm corresponding to the exit pupil distance of the imaging optical system. The diffusion plate 21c and the light shielding plate 21e are integrally formed by bonding, and the opening 21d is half the size of the exit pupil with brightness of f2.8. The portions other than the opening 21d of the light shielding plate 21e completely shield light.

図９に示す一般用素子検査装置と同様に、ウエハープローバー２２のステージ（不図示）上のシリコンウエハー１２には複数の固体撮像素子１３が形成されており、撮像素子１３と同じ大きさの開口（不図示）を有するプローブカードがウエハー１２上にセットされ、プローブカードと撮像素子１３とが電気的に接続されるとともに、検査用光源２１からの光をプローブカードの開口を介して撮像素子１３に照射する。なお、図１１では説明を解りやすくするためにプローブカードの下に位置するウエハー１２が見えるように図示したが、実際のプローブカードは開口以外の部分は不透明である。一つの撮像素子１３の検査が終了すると、ステージが移動して次の撮像素子１３がプローブカードの開口の真下にセットされ、これを繰り返してウエハー１２上のすべての撮像素子１３の検査が行われる。   As in the general element inspection apparatus shown in FIG. 9, a plurality of solid-state imaging elements 13 are formed on the silicon wafer 12 on the stage (not shown) of the wafer prober 22, and the opening has the same size as the imaging element 13. A probe card having (not shown) is set on the wafer 12, the probe card and the image sensor 13 are electrically connected, and light from the inspection light source 21 is passed through the opening of the probe card. Irradiate. In FIG. 11, for ease of explanation, the wafer 12 positioned below the probe card is shown so as to be visible, but the actual probe card is opaque except for the opening. When the inspection of one image sensor 13 is completed, the stage moves and the next image sensor 13 is set immediately below the opening of the probe card, and this is repeated to inspect all the image sensors 13 on the wafer 12. .

撮像素子１３の検査途中で焦点検出画素３ａ、３ｂの検査を行うときは、照明光学系２１ｂとウエハープローバー２２のプローブカードとの間に、駆動装置２１ｆによって拡散板２１ｃと遮光板２１ｅを挿入する。そして、ランプ２１ａを点灯し、照明用光学系２１ｂ、拡散板２１ｃおよび遮光板２１ｅの開口２１ｄを介して撮像素子１３上の焦点検出画素３ａ、３ｂへ光を照射する。   When the focus detection pixels 3a and 3b are inspected during the inspection of the image pickup device 13, the diffusion plate 21c and the light shielding plate 21e are inserted between the illumination optical system 21b and the probe card of the wafer prober 22 by the driving device 21f. . Then, the lamp 21a is turned on, and the focus detection pixels 3a and 3b on the image sensor 13 are irradiated with light through the illumination optical system 21b, the diffusion plate 21c, and the opening 21d of the light shielding plate 21e.

ここで、焦点検出画素３ａ、３ｂの検査手順を説明する。遮光板２１ｅの開口２１ｄは図７に示す射出瞳１０の左半分の領域１０ｂに相当し、この開口２１ｄからマイクロレンズ４を介して焦点検出画素３ａ、３ｂへ光を照射する。この状態で、右側に光電変換部８を有する焦点検出画素３ｂ（図５(ｂ)参照）の出力信号をＳとして測定するとともに、左側に光電変換部７を有する焦点検出画素３ａ（図５(ａ)参照）の出力信号をＮとして測定する。   Here, the inspection procedure of the focus detection pixels 3a and 3b will be described. The opening 21d of the light shielding plate 21e corresponds to the left half region 10b of the exit pupil 10 shown in FIG. 7, and the focus detection pixels 3a and 3b are irradiated with light from the opening 21d through the microlens 4. In this state, the output signal of the focus detection pixel 3b having the photoelectric conversion unit 8 on the right side (see FIG. 5B) is measured as S, and the focus detection pixel 3a having the photoelectric conversion unit 7 on the left side (FIG. 5 ( The output signal of a) is measured as N.

次に、拡散板２１ｃと遮光板２１ｅを駆動装置２１ｆにより１８０度回転させると、図１３に示すように開口２１ｄ’を備えた遮光板２１ｅ’になり、この開口２１ｄ’は図８に示す射出瞳１０の右半分の領域１０ｄに相当し、この開口２１ｄ’からマイクロレンズ４を介して焦点検出画素３ａ、３ｂへ光を照射する。この状態で、右側に光電変換部８を有する焦点検出画素３ｂ（図５(ｂ)参照）の出力信号をＮとして測定するとともに、左側に光電変換部７を有する焦点検出画素３ａ（図５(ａ)参照）の出力信号をＳとして測定する。   Next, when the diffusing plate 21c and the light shielding plate 21e are rotated 180 degrees by the driving device 21f, the light shielding plate 21e 'having an opening 21d' is formed as shown in FIG. 13, and the opening 21d 'is emitted as shown in FIG. This corresponds to the right half region 10d of the pupil 10, and light is emitted from the opening 21d 'to the focus detection pixels 3a and 3b through the microlens 4. In this state, the output signal of the focus detection pixel 3b having the photoelectric conversion unit 8 on the right side (see FIG. 5B) is measured as N, and the focus detection pixel 3a having the photoelectric conversion unit 7 on the left side (see FIG. The output signal of a) is measured as S.

以上の手順で撮像素子１３内のすべての焦点検出画素３ａ、３ｂの出力Ｓ、Ｎを測定し、焦点検出画素３ａ、３ｂごとに比Ｓ／Ｎを算出する。そして、撮像素子１３の中の焦点検出画素３ａ、３ｂの最小の比Ｓ／Ｎが所定値以下であった場合には、その撮像素子１３を不良と判定し、製品への組み込みを禁止する。あるいは、Ｓ／Ｎが所定値以下である焦点検出画素３ａ、３ｂは、製品では不使用とされてもよい。   With the above procedure, the outputs S and N of all the focus detection pixels 3a and 3b in the image sensor 13 are measured, and the ratio S / N is calculated for each focus detection pixel 3a and 3b. If the minimum ratio S / N of the focus detection pixels 3a and 3b in the image pickup device 13 is equal to or less than a predetermined value, the image pickup device 13 is determined to be defective and its incorporation into a product is prohibited. Alternatively, the focus detection pixels 3a and 3b whose S / N is less than or equal to a predetermined value may be unused in the product.

焦点検出画素３ａ、３ｂの検査時には、焦点検出画素３ａ、３ｂの出力を撮像画素２の出力と比較し、撮像画素出力に対する焦点検出画素出力の比を求め、焦点検出画素３ａ、３ｂの相対感度を検出する。検出感度の最小値が予め設定された良品判定基準感度以下の場合には、その撮像素子１を不良品と判定し、製品への組み込みを禁止する。   When inspecting the focus detection pixels 3a and 3b, the output of the focus detection pixels 3a and 3b is compared with the output of the imaging pixel 2 to obtain the ratio of the focus detection pixel output to the imaging pixel output, and the relative sensitivity of the focus detection pixels 3a and 3b. Is detected. If the minimum value of the detection sensitivity is equal to or lower than a preset good product determination reference sensitivity, the image pickup device 1 is determined as a defective product, and incorporation into the product is prohibited.

上述した一実施の形態では、一つの焦点検出画素の中に一つの光電変換部を備えた焦点検出画素３ａ、３ｂを例に挙げて説明したが、一つの焦点検出画素の中に一対の光電変換部を備え、射出瞳の一対の領域を通過した一対の光束を一対の光電変換部で受光して一対の焦点検出用信号を出力する焦点検出画素に対しても本発明を適用することができる。   In the above-described embodiment, the focus detection pixels 3a and 3b including one photoelectric conversion unit in one focus detection pixel have been described as an example. However, a pair of photoelectric detection pixels in one focus detection pixel are described. The present invention can also be applied to a focus detection pixel that includes a conversion unit and receives a pair of light beams that have passed through a pair of regions of the exit pupil, and outputs a pair of focus detection signals. it can.

図１４は変形例の焦点検出画素３０を示す正面図であり、図１５は焦点検出画素３０が組み込まれた撮像素子３１を示す正面図である。焦点検出画素３０は、マイクロレンズ４と一対の光電変換部３２ａ、３２ｂから構成され、光電変換部３２ａ、３２ｂの形状は矩形である。焦点検出画素３０の一対の光電変換部３２ａと３２ｂは左右方向に配列されており、撮像素子３１上では複数の焦点検出画素３０が一対の光電変換部３２ａ、３２ｂと同じ配列方向、すなわち左右方向に配列されている。   FIG. 14 is a front view showing a focus detection pixel 30 of a modification, and FIG. 15 is a front view showing an image sensor 31 in which the focus detection pixel 30 is incorporated. The focus detection pixel 30 includes a microlens 4 and a pair of photoelectric conversion units 32a and 32b, and the photoelectric conversion units 32a and 32b have a rectangular shape. The pair of photoelectric conversion units 32a and 32b of the focus detection pixel 30 are arranged in the left-right direction, and the plurality of focus detection pixels 30 on the image sensor 31 are arranged in the same arrangement direction as the pair of photoelectric conversion units 32a, 32b, that is, the left-right direction. Is arranged.

図１６は、撮像光学系の射出瞳３５上の一対の領域の内の一方の領域３５ａを通過した光束（焦点検出画素３０の光電変換部３２ｂが焦点検出に用いる光束）が、焦点検出画素３０のマイクロレンズ４を介して光電変換面３６へ入射する様子を示す。射出瞳３５の領域３５ａを通過した光束は、理想的には焦点検出画素３０の光電変換部３２ｂへ入射するはずであるが、上述した問題によりこの光束は光電変換面３６上の領域３７へ入射し、光電変換部３２ｂ以外の領域に漏れ出してしまう。   FIG. 16 shows that the light beam that has passed through one of the pair of regions 35a on the exit pupil 35 of the image pickup optical system (the light beam used for focus detection by the photoelectric conversion unit 32b of the focus detection pixel 30) is the focus detection pixel 30. A state in which the light enters the photoelectric conversion surface 36 through the microlens 4 is shown. The light beam that has passed through the region 35a of the exit pupil 35 should ideally be incident on the photoelectric conversion unit 32b of the focus detection pixel 30, but this light beam is incident on the region 37 on the photoelectric conversion surface 36 due to the problem described above. Then, it leaks out to a region other than the photoelectric conversion unit 32b.

図１７は、射出瞳３５上の一対の領域の内の上記一方の領域３５ａ以外の領域３５ｂを通過した光束（焦点検出画素３０の光電変換部３２ｂが焦点検出に用いない光束）が、焦点検出画素３０のマイクロレンズ４を介して光電変換面３６へ入射する様子を示す。射出瞳３５の領域３５ｂを通過した光束は、理想的には焦点検出画素３０の光電変換部３２ｂ以外の領域へ入射するはずであるが、上述した問題によりこの光束は光電変換面３６上の領域３８へ入射し、光電変換部３２ｂへ漏れ込んでしまう。   FIG. 17 shows focus detection of a light beam that has passed through a region 35b other than the one region 35a in the pair of regions on the exit pupil 35 (light beam that the photoelectric conversion unit 32b of the focus detection pixel 30 does not use for focus detection). A mode that it injects into the photoelectric conversion surface 36 through the micro lens 4 of the pixel 30 is shown. The light beam that has passed through the region 35b of the exit pupil 35 should ideally be incident on a region other than the photoelectric conversion unit 32b of the focus detection pixel 30, but due to the problem described above, this light beam is a region on the photoelectric conversion surface 36. 38 and leaks into the photoelectric conversion unit 32b.

なお、図１６および図１７では、焦点検出画素３０上の一対の光電変換部３２ａ、３２ｂの内の右側の光電変換部３２ｂを例に挙げて説明するが、左側の光電変換部３２ａについても同様な光束の漏れ出しと漏れ込みが発生する。この光電変換部３２ａにおいては、射出瞳３５の光束を通過する領域が左右対称に変わるだけであり、図示と説明を省略する。なお、焦点検出画素３０の光電変換部３２ａは、図１６に示す射出瞳３５上の一方の領域３５ａと左右対象位置にある他方の領域を通過した光束を焦点検出用光束として受光する。   16 and 17, the right photoelectric conversion unit 32b of the pair of photoelectric conversion units 32a and 32b on the focus detection pixel 30 will be described as an example, but the same applies to the left photoelectric conversion unit 32a. Leakage of light flux and leakage occur. In the photoelectric conversion unit 32a, only the region of the exit pupil 35 that passes through the light flux changes symmetrically, and illustration and description thereof are omitted. The photoelectric conversion unit 32a of the focus detection pixel 30 receives a light beam that has passed through one region 35a on the exit pupil 35 and the other region at the left and right target positions shown in FIG. 16 as a focus detection light beam.

焦点検出画素３０の光電変換部３２ｂは、図１６に示す射出瞳３５上の一対の領域の内の一方の領域３５ａを通過した光束と、図１７に示す射出瞳３５上の前記一対の領域３５ａ以外の領域３５ｂを通過した光束の一部とを受光し、受光光束の光強度に応じた信号を出力する。一方、焦点検出画素３０の光電変換部３２ａは、図１６に示す射出瞳３５上の一方の領域３５ａと左右対象位置にある他方の領域（不図示）を通過した光束と、図１７に示す射出瞳３５上の領域３５ｂと左右対象位置にある領域（不図示）を通過した光束の一部とを受光し、受光光束の光強度に応じた信号を出力する。これら焦点検出画素３０の一対の光電変換部３２ａと３２ｂの出力信号は、撮像光学系の焦点調節状態を示す一対の位相情報となる。   The photoelectric conversion unit 32b of the focus detection pixel 30 includes a light beam that has passed through one region 35a of the pair of regions on the exit pupil 35 illustrated in FIG. 16 and the pair of regions 35a on the exit pupil 35 illustrated in FIG. A part of the light beam that has passed through the other region 35b is received, and a signal corresponding to the light intensity of the received light beam is output. On the other hand, the photoelectric conversion unit 32a of the focus detection pixel 30 has a light beam that has passed through one region 35a on the exit pupil 35 shown in FIG. 16 and the other region (not shown) at the left and right target positions, and the exit shown in FIG. The region 35b on the pupil 35 and a part of the light beam that has passed through the region (not shown) at the left and right target positions are received, and a signal corresponding to the light intensity of the received light beam is output. The output signals of the pair of photoelectric conversion units 32a and 32b of the focus detection pixel 30 become a pair of phase information indicating the focus adjustment state of the imaging optical system.

焦点検出画素３０において、図１６に示す一方の領域３５ａからの光束による光電変換部３２ｂの出力信号をＳとし、図１７に示す一方の領域３５ａ以外の領域３５ｂからの光束による光電変換部３２ｂの出力信号をＮとすると、上述したように比Ｓ／Ｎは位相差情報の正確さを表すパラメーターであり、焦点検出画素３０の一方の光電変換部３２ｂの焦点検出性能を示す指標値とすることができる。一方、図１６に示す一方の領域３５ａと左右対象位置にある他方の領域（不図示）からの光束による光電変換部３２ａの出力信号をＳとし、図１７に示す領域３５ｂと左右対象位置にある領域（不図示）からの光束による光電変換部３２ａの出力信号をＮとすると、比Ｓ／Ｎは位相差情報の正確さを表すパラメーターであり、他方の光電変換部３２ａの焦点検出性能を示す指標値とすることができる。   In the focus detection pixel 30, the output signal of the photoelectric conversion unit 32b by the light beam from one region 35a shown in FIG. 16 is set as S, and the photoelectric conversion unit 32b by the light beam from the region 35b other than the one region 35a shown in FIG. Assuming that the output signal is N, as described above, the ratio S / N is a parameter indicating the accuracy of the phase difference information, and is an index value indicating the focus detection performance of one photoelectric conversion unit 32b of the focus detection pixel 30. Can do. On the other hand, the output signal of the photoelectric conversion unit 32a by the light beam from one region 35a shown in FIG. 16 and the other region (not shown) at the left and right target positions is S, and is located at the left and right target positions as shown in FIG. When the output signal of the photoelectric conversion unit 32a by a light beam from a region (not shown) is N, the ratio S / N is a parameter indicating the accuracy of the phase difference information and indicates the focus detection performance of the other photoelectric conversion unit 32a. It can be an index value.

一対の光電変換部３２ａ、３２ｂを内蔵する焦点検出画素３０に対しては、図１１に示す遮光板２１ｅの代わりに、図１６に示す領域３５ａおよび図１７に示す領域３５ｂと同じ開口形状の遮光板を用い、光電変換部３２ａと３２ｂで遮光板を１８０度回転して上記手順と同様な手順で測定を行えばよい。   For the focus detection pixel 30 including the pair of photoelectric conversion units 32a and 32b, the light shielding plate having the same opening shape as the region 35a illustrated in FIG. 16 and the region 35b illustrated in FIG. 17 is used instead of the light shielding plate 21e illustrated in FIG. Using a plate, the light shielding plate may be rotated 180 degrees by the photoelectric conversion units 32a and 32b, and measurement may be performed in the same procedure as described above.

なお、上述した一実施の形態では焦点検出画素を左右に配列した撮像素子を例に挙げて説明したが、焦点検出画素の配列方向は上下あるいは斜め方向であってもよい。また、焦点検出画素上の光電変換部の形状は矩形に限定されず、例えば半円形としてもよい。さらに、上述した一実施の形態では比Ｓ／Ｎを焦点検出性能指標値としたが、ＳとＮの差を焦点検出性能指標値としてもよい。   In the above-described embodiment, the imaging element in which the focus detection pixels are arranged on the left and right is described as an example. However, the arrangement direction of the focus detection pixels may be up and down or oblique. Further, the shape of the photoelectric conversion unit on the focus detection pixel is not limited to a rectangle, and may be, for example, a semicircle. Furthermore, in the above-described embodiment, the ratio S / N is used as the focus detection performance index value, but the difference between S and N may be used as the focus detection performance index value.

以上説明したように、一実施の形態によれば、撮像光学系により結像された像を撮像するための撮像画素が二次元配列された撮像素子の一部に、撮像画素の代わりに光学系の焦点調節状態を検出するための焦点検出画素を複数個配列した撮像素子を検査する素子検査用光源２１であって、照明灯２１ａと、照明光学系２１ｂと、照明灯２１ａから発せられ照明光学系２１ｂを透過した光束を、所定形状の開口２１ｄ、２１ｄ’により制限して撮像素子１３上の焦点検出画素に照射する遮光板２１ｃ、２１ｃ’とを備え、遮光板２１ｃ、２１ｃ’は、撮像光学系の射出瞳の一対の領域の内の一方の領域を通過する光束と同等な光束を生成する第１開口２１ｄを有する第１遮光板２１ｅと、射出瞳の一方の領域以外の領域を通過する光束と同等な光束を生成する第２開口２１ｄ’を有する第２遮光板２１ｅ’とからなるように構成したので、焦点検出画素が配列された撮像素子の焦点検出性能を、撮像素子を撮像装置に組み込む前に簡単に評価することができる。   As described above, according to an embodiment, an optical system is used instead of an imaging pixel in a part of an imaging element in which imaging pixels for imaging an image formed by an imaging optical system are two-dimensionally arranged. An element inspection light source 21 for inspecting an image pickup device in which a plurality of focus detection pixels for detecting the focus adjustment state of the light source is arranged, and is emitted from the illumination lamp 21a, the illumination optical system 21b, and the illumination lamp 21a. The light shielding plates 21c and 21c ′ are provided with light shielding plates 21c and 21c ′ that irradiate the focus detection pixels on the image sensor 13 while restricting the light beam transmitted through the system 21b by apertures 21d and 21d ′ having a predetermined shape. A first light-shielding plate 21e having a first opening 21d that generates a light beam equivalent to a light beam that passes through one of the pair of regions of the exit pupil of the optical system, and a region other than the one region of the exit pupil. Equivalent to the luminous flux Since it is configured to include the second light shielding plate 21e ′ having the second opening 21d ′ for generating a bundle, the focus detection performance of the image pickup element in which the focus detection pixels are arranged is measured before the image pickup element is incorporated in the image pickup apparatus. Can be easily evaluated.

また、一実施の形態によれば、素子検査用光源２１の第１開口２１ｄを撮像光学系の射出瞳を二等分した一方の領域に相当する開口とし、第２開口２１ｄ’を射出瞳を二等分した他方の領域に相当する開口としたので、撮像光学系の射出瞳の一対の領域を通過する一対の焦点検出用光束を受光する焦点検出画素の焦点検出性能を、１枚の遮光板を回転させて用いることによって簡単に評価することができる。   According to one embodiment, the first opening 21d of the element inspection light source 21 is an opening corresponding to one region obtained by dividing the exit pupil of the imaging optical system into two equal parts, and the second opening 21d ′ is the exit pupil. Since the aperture is equivalent to the other half of the area, the focus detection performance of the focus detection pixel that receives a pair of focus detection light beams that pass through the pair of exit pupil areas of the imaging optical system is reduced by one light shielding. It can be easily evaluated by rotating the plate.

一実施の形態によれば、素子検査用光源２１の遮光板２１ｅの照明灯２１ａ側に光を拡散させるための拡散板２１ｃを設置したので、実際の撮像光学系の射出瞳上の一対の領域を通る焦点検出用光束に近い素子検査用光束を撮像素子に照射することができる。   According to the embodiment, since the diffusion plate 21c for diffusing light is installed on the illumination lamp 21a side of the light shielding plate 21e of the element inspection light source 21, a pair of regions on the exit pupil of the actual imaging optical system The image sensor can be irradiated with a light beam for element inspection close to a focus light beam for focus detection passing through.

一実施の形態によれば、第１遮光板２１ｅを用いて焦点検出画素を照射した場合の焦点検出画素の出力信号Ｓと、第２遮光板２１ｅ’を用いて焦点検出画素を照射した場合の焦点検出画素の出力信号Ｎとを測定し、出力信号Ｓと力信号Ｎとに基づいて撮像素子の焦点検出性能を判定するようにしたので、撮像素子の焦点検出性能を、実際の使用状態に近い状態で正確に評価することができる。   According to the embodiment, the output signal S of the focus detection pixel when the focus detection pixel is irradiated using the first light shielding plate 21e and the focus detection pixel when the focus detection pixel is irradiated using the second light shielding plate 21e ′. Since the output signal N of the focus detection pixel is measured and the focus detection performance of the image sensor is determined based on the output signal S and the force signal N, the focus detection performance of the image sensor is changed to the actual use state. Accurate evaluation can be performed in a close state.

検査対象の撮像素子の光電変換部を正面から見た図Front view of the photoelectric conversion part of the image sensor to be inspected 撮像画素の正面図Front view of imaging pixels 撮像画素の断面図Cross section of imaging pixel 焦点検出画素の正面図Front view of focus detection pixels 焦点検出画素の断面図Cross section of focus detection pixel 撮像素子上の焦点検出画素と撮像光学系の射出瞳との関係を示す図The figure which shows the relationship between the focus detection pixel on an image sensor, and the exit pupil of an imaging optical system 射出瞳の左半分の領域を通過した光束（焦点検出画素が焦点検出に用いる光束）が、焦点検出画素のマイクロレンズを介して光電変換面へ入射する様子を示す図The figure which shows a mode that the light beam (The light beam which a focus detection pixel uses for focus detection) which passed the area | region of the left half of an exit pupil injects into a photoelectric conversion surface through the micro lens of a focus detection pixel. 射出瞳の残り半分の領域を通過した光束（焦点検出画素が焦点検出に用いない光束）が、焦点検出画素のマイクロレンズを介して光電変換面へ入射する様子を示す図The figure which shows a mode that the light beam (The light beam which a focus detection pixel does not use for focus detection) which passed the other half area | region of the exit pupil injects into a photoelectric conversion surface through the micro lens of a focus detection pixel. シリコンウエハー上に形成された撮像素子の一般的な検査方法を説明するための図The figure for demonstrating the general inspection method of the image pick-up element formed on the silicon wafer 一実施の形態の素子検査装置の構成を示す図The figure which shows the structure of the element inspection apparatus of one embodiment 検査用光源の詳細な構成を示す斜視図The perspective view which shows the detailed structure of the light source for a test | inspection 検査用光源の一部と撮像素子上の焦点検出画素の横断面図Cross-sectional view of part of inspection light source and focus detection pixel on image sensor １８０度回転した遮光板を示す図The figure which shows the light-shielding plate rotated 180 degrees 変形例の焦点検出画素を示す正面図Front view showing a modified focus detection pixel 焦点検出画素が組み込まれた撮像素子を示す正面図Front view showing an image sensor incorporating focus detection pixels 撮像光学系の射出瞳上の一対の領域の内の一方の領域を通過した光束（焦点検出画素の光電変換部が焦点検出に用いる光束）が、焦点検出画素のマイクロレンズを介して光電変換面へ入射する様子を示す図The light beam that has passed through one of the pair of regions on the exit pupil of the imaging optical system (the light beam used by the photoelectric conversion unit of the focus detection pixel for focus detection) passes through the micro lens of the focus detection pixel. Figure showing how the light enters 射出瞳上の一対の領域の内の上記一方の領域以外の領域を通過した光束（焦点検出画素の光電変換部が焦点検出に用いない光束）が、焦点検出画素のマイクロレンズを介して光電変換面へ入射する様子を示す図A light beam that has passed through a region other than the one of the pair of regions on the exit pupil (light beam that the photoelectric conversion unit of the focus detection pixel does not use for focus detection) undergoes photoelectric conversion via the micro lens of the focus detection pixel. Diagram showing how light enters the surface

符号の説明Explanation of symbols

２；撮像画素、３ａ、３ｂ、７，８，３２ａ、３２ｂ；光電変換部、２１；検査用光源、３０；焦点検出画素、２１ａ；ランプ、２１ｂ；照明光学系、２１ｃ；拡散板、２１ｄ；開口、２１ｅ；遮光板、２１ｆ；駆動装置、２２；ウエハープローバー、２３；テスター 2; imaging pixels, 3a, 3b, 7, 8, 32a, 32b; photoelectric conversion unit, 21; inspection light source, 30; focus detection pixel, 21a; lamp, 21b; illumination optical system, 21c; Opening, 21e; light shielding plate, 21f; driving device, 22; wafer prober, 23; tester

Claims (7)

撮像光学系により結像された像を撮像するための撮像画素が二次元配列された撮像素子の一部に、前記撮像光学系の焦点調節状態を検出するための焦点検出画素を複数個配列した撮像素子を検査する素子検査用光源であって、
照明灯と、
照明光学系と、
前記照明灯から発せられ前記照明光学系を透過した光束を、所定形状の開口により制限して前記撮像素子上の前記焦点検出画素に照射する遮光板とを備え、
前記遮光板は、前記撮像光学系の射出瞳の一対の領域の内の一方の領域を通過する光束と同等な光束を前記照明光学系を透過した光束より生成する第１開口を有する第１遮光板と、前記射出瞳の前記一方の領域以外の領域を通過する光束と同等な光束を前記照明光学系を透過した光束より生成する第２開口を有する第２遮光板とからなることを特徴とする素子検査用光源。 A plurality of focus detection pixels for detecting the focus adjustment state of the imaging optical system are arranged in a part of an imaging element in which imaging pixels for imaging an image formed by the imaging optical system are two-dimensionally arranged. A light source for inspecting an image sensor,
With lighting,
Illumination optics,
A light-shielding plate that irradiates the focus detection pixels on the image sensor by limiting a light beam emitted from the illumination lamp and transmitted through the illumination optical system with an opening having a predetermined shape,
The light-shielding plate has a first light-shielding having a first opening that generates a light beam equivalent to a light beam passing through one of the pair of regions of the exit pupil of the imaging optical system from the light beam transmitted through the illumination optical system. And a second light-shielding plate having a second aperture for generating a light beam equivalent to a light beam passing through a region other than the one region of the exit pupil from a light beam transmitted through the illumination optical system. Light source for device inspection. 請求項１に記載の素子検査用光源において、
前記第１開口を前記射出瞳を二等分した一方の領域に相当する開口とし、前記第２開口を前記射出瞳を二等分した他方の領域に相当する開口とすることを特徴とする素子検査用光源。 The light source for element inspection according to claim 1,
The element in which the first opening is an opening corresponding to one area obtained by dividing the exit pupil into two equal parts, and the second opening is an opening corresponding to the other area obtained by dividing the exit pupil into two equal parts. Light source for inspection. 請求項１または請求項２に記載の素子検査用光源において、
前記遮光板の前記照明灯側に、光を拡散させるための拡散板を設置することを特徴とする素子検査用光源。 In the element inspection light source according to claim 1 or 2,
A light source for element inspection, comprising a diffusion plate for diffusing light on the side of the illuminating lamp of the light shielding plate. 請求項１〜３のいずれか一項に記載の素子検査用光源において、
前記遮光板を回転させる駆動手段を備え、
前記光学系の射出瞳の一対の領域の内の一方の領域を通過する光束を焦点検出用光束として受光する前記焦点検出画素を検査する場合と、前記一対の領域の内の他方の領域を通過する光束を焦点検出用光束として受光する前記焦点検出画素を検査する場合とで、前記駆動手段により前記遮光板を１８０度回転させることを特徴とする素子検査用光源。 In the light source for element inspection according to any one of claims 1 to 3,
Drive means for rotating the light shielding plate;
When inspecting the focus detection pixel that receives a light beam passing through one of the pair of regions of the exit pupil of the optical system as a focus detection light beam, and passing through the other region of the pair of regions A light source for element inspection, wherein the light shielding plate is rotated 180 degrees by the driving means when inspecting the focus detection pixel that receives a light beam to be detected as a focus detection light beam. 請求項１〜４のいずれか一項に記載の検査用光源と、
前記第１遮光板を用いて前記焦点検出画素を照射した場合の前記焦点検出画素の出力信号Ｓと、前記第２遮光板を用いて前記焦点検出画素を照射した場合の前記焦点検出画素の出力信号Ｎとを測定する測定手段と、
前記出力信号Ｓと前記出力信号Ｎとに基づいて前記撮像素子の焦点検出性能を判定する判定手段とを備えることを特徴とする素子検査装置。 The inspection light source according to any one of claims 1 to 4,
The output signal S of the focus detection pixel when the focus detection pixel is irradiated using the first light shielding plate, and the output of the focus detection pixel when the focus detection pixel is irradiated using the second light shielding plate Measuring means for measuring the signal N;
An element inspection apparatus comprising: a determination unit that determines a focus detection performance of the imaging element based on the output signal S and the output signal N. 請求項５に記載の素子検査装置において、
前記判定手段は、前記撮像素子の中に前記出力信号Ｓと前記出力信号Ｎの比Ｓ／Ｎが予め設定した判定基準値以下の前記焦点検出画素が含まれていた場合には、当該撮像素子を不良品と判定することを特徴とする素子検査装置。 In the element inspection apparatus according to claim 5,
When the focus detection pixel in which the ratio S / N between the output signal S and the output signal N is less than or equal to a predetermined determination reference value is included in the image sensor, the determination unit A device inspection apparatus characterized by determining that the product is defective. 撮像光学系により結像された像を撮像するための撮像画素が二次元配列された撮像素子の一部に、前記撮像光学系の焦点調節状態を検出するための焦点検出画素を複数個配列した撮像素子を検査する素子検査方法であって、
照明灯から発せられ照明光学系を透過した光束を、所定形状の開口により制限して前記撮像素子上の前記焦点検出画素に照射する際に、
前記撮像光学系の射出瞳の一対の領域の内の一方の領域を通過する光束と同等な光束を前記照明光学系を透過した光束より生成する第１開口により前記光束を制限して前記焦点検出画素を照射した場合の前記焦点検出画素の出力信号Ｓと、前記射出瞳の前記一方の領域以外の領域を通過する光束と同等な光束を前記照明光学系を透過した光束より生成する第２開口により前記光束を制限して前記焦点検出画素を照射した場合の前記焦点検出画素の出力信号Ｎとを測定し、前記出力信号Ｓと前記出力信号Ｎの比Ｓ／Ｎに基づいて前記撮像素子の焦点検出性能を評価することを特徴とする素子検査方法。 A plurality of focus detection pixels for detecting the focus adjustment state of the imaging optical system are arranged in a part of an imaging element in which imaging pixels for imaging an image formed by the imaging optical system are two-dimensionally arranged. An element inspection method for inspecting an image sensor,
When irradiating the focus detection pixel on the image sensor by limiting the light beam emitted from the illumination lamp and transmitted through the illumination optical system with an opening having a predetermined shape,
The focus detection is performed by limiting the light beam by a first aperture that generates a light beam equivalent to a light beam passing through one of the pair of regions of the exit pupil of the imaging optical system from the light beam transmitted through the illumination optical system. A second aperture that generates a light beam equivalent to a light beam passing through an area other than the one area of the exit pupil from a light beam that has passed through the illumination optical system, and an output signal S of the focus detection pixel when the pixel is irradiated And measuring the output signal N of the focus detection pixel when the focus detection pixel is irradiated with the light flux being limited by the ratio, and based on the ratio S / N of the output signal S and the output signal N An element inspection method characterized by evaluating focus detection performance.
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