JP4335104B2 - Photodiode array and spectrometer - Google Patents

Description

  The present invention relates to a photodiode array and a spectroscope.

As a technique related to a photodiode that is a light receiving element, for example, one having an overflow drain portion as 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.
Japanese Patent Laid-Open No. 7-50402

  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 length of 50 μm 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 provided on the short side in the planar shape of the photosensitive region.

  Here, an example of the light detection means of the spectroscope described above will be described with reference to the drawings. FIG. 10 is a plan view showing the configuration of the photodetecting means of the spectroscope, and FIG. 11 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 one short side. In the photosensitive region 42, for example, a semiconductor layer 46 containing P-type (or N-type) impurities is formed so as to be embedded in the surface of the semiconductor layer 47 containing N-type (or P-type) impurities. The

  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, in order to achieve high photosensitivity in the photodiode 40 used as the photodetecting means, the impurity concentration of an impurity semiconductor layer (hereinafter simply referred to as an impurity layer) constituting the photosensitive region 42 may be lowered. This means that if the impurity concentration of the impurity layer is high, the photoresponse speed is fast but the photosensitivity is low. Conversely, if the impurity concentration of the impurity layer is low, the photoresponse speed is slow but the photosensitivity is high. This is derived from one characteristic of the photodiode. Here, the light response speed means a time interval from the generation of carriers generated in the impurity layer by the irradiation of light to the extraction by the electrode 43. This optical response speed is slow when the electric resistance value in the impurity layer is high (impurity concentration is low) and fast when the electric resistance value in the impurity layer 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.

  However, if the impurity concentration of the impurity layer 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 at a location far from the electrode 43 in the photosensitive region 42, that is, on the side opposite to the side where 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.

  Accordingly, an object of the present invention is to provide a photodiode array having a high wavelength resolution and a high light response speed while maintaining high photosensitivity, and a spectroscope using the photodiode array as a light detection means. .

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 sides forming the planar shape of the photosensitive region. A plurality of photodiodes arranged in parallel so as to be adjacent to each other and provided on one short side in the planar shape of the photosensitive region, and for extracting charges generated by light incident on the photosensitive region A conductive wire portion electrically connected to the electrode, and a plurality of contact portions for electrically connecting the conductive wire portion and the electrode to the photodiode, the photodiode comprising: In a second semiconductor layer in which the first semiconductor layer that contains the conductive type impurity and constitutes the photosensitive region contains a second conductive type impurity different from the first conductive type While being formed, the plurality of contact portions are electrically connected to the semiconductor layer of the first through respectively the silicon thermal oxide film on said first semiconductor layer, the contact portion and the conductor portion Is made of a material having a lower electrical resistance than the first semiconductor layer.

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 is arranged in parallel so that the long sides are adjacent to each other. An electrode for extracting carrier charges generated according to light is provided on one short side of the two short sides in the planar shape of the photosensitive region. 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, for example, a spectroscope. The electrode has an electric resistance lower than that of the first semiconductor layer constituting the photosensitive region, and is electrically connected to the first semiconductor layer via a contact portion and a conductor portion that transmit carriers at high speed. . For this reason, even when the impurity concentration of the first semiconductor layer is set to be low, for example, about 10 ¹⁸ cm ⁻³ or less in order to obtain high photosensitivity, the carrier charge generated according to the incident light is Since it is possible to move not only to the first semiconductor layer having a high value but also to the electrode through a contact portion and a conducting wire portion having a low electric resistance value, it is possible to improve the light response speed while maintaining high light sensitivity.

In the present invention, the conductor portion is made of a material capable of blocking incident light, and is formed in a shape that covers part or all of the vicinity of the outer periphery in the planar shape of the photosensitive region with respect to the incident light. It is preferable. In this case, since the conductor part has not only the function of transmitting the carriers generated in the photosensitive region as described above to the electrode at a high speed but also a function as a light shielding film, a light shielding film is newly provided outside the conductor part. There is no need to provide it. For this reason, the manufacturing cost and manufacturing process for the photodiode array can be reduced. Furthermore, the conductive wire portion has a function as a light shielding film as described above, and has a shape that covers the vicinity of the outer periphery in the planar shape of the photosensitive region from incident light. For this reason, when the SiO ₂ layer is formed on the surface of the light sensitive region (first semiconductor layer), incident light to the region near the outer periphery and in contact with the SiO ₂ layer can be shielded. As described above, when light enters, an increase in dark current generated in the region due to the charge generated in the SiO ₂ layer can be suppressed, and thereby low noise can be realized.

  In the present invention, it is preferable that the contact portion and the conductor portion are integrally formed of the same material. As a result, the manufacturing cost and manufacturing process for the photodiode array can be reduced.

  In the present invention, it is preferable that the electrode, the conductor portion, and the contact portion are integrally formed of the same material. As a result, the manufacturing cost and manufacturing process for the photodiode array can be more effectively reduced.

  In the present invention, it is preferable that the contact portion is provided at least on the two short sides in the planar shape of the photosensitive region. As a result, a carrier generated on either of the two short sides in the elongated planar shape of the photosensitive region can reach the contact portion immediately from the generation point, so that a higher light response speed can be realized. .

  In the present invention, it is preferable that one or a plurality of contact portions be provided on one or both of the long sides of the two long sides in the planar shape of the photosensitive region. For this reason, even a carrier generated within a wider range along the long side of the long and narrow planar shape of the photosensitive region can reach the contact portion immediately from the point of occurrence, thereby realizing a faster light response speed. it can.

  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, the photodiode array as the light detection means has a high wavelength resolution and a fast optical response speed while maintaining high photosensitivity, so that a highly accurate spectrometer can be realized.

  According to the present invention, it is possible to provide a photodiode array having a high wavelength resolution and a high light response speed while maintaining a high light sensitivity, and a spectroscope using the photodiode array as a light detection means.

  Hereinafter, a photodiode according to the present embodiment and a photodiode array including a plurality of the photodiodes 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.

  First, the photodiode according to this embodiment will be described with reference to FIG. 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.

First, the configuration of the photodiode 10 will be described with reference to FIG. The photodiode 10 includes a first conductivity type impurity layer 1 as a first semiconductor layer, a second conductivity type impurity layer 2 as a second semiconductor layer, and a silicon thermal oxide film (SiO ₂ ) 3. The photodiode 10 is provided with electrodes 4 and 5, contact portions 6 (6 a and 6 b), a conductive wire portion 7, and a light shielding film 8. 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.

The first conductivity type impurity layer 1 is a silicon (Si) layer with a first conductivity type impurity having a low concentration, for example, about 10 ¹⁸ cm ⁻³ or less (arsenic or the like when the first conductivity type is N type). In the case of the P type, boron or the like is included. The second conductivity type impurity layer 2 includes a silicon (Si) layer and a second conductivity type impurity (boron or the like when the first conductivity type is N type and the second conductivity type is P type). Is P type and the second conductivity type is N type, such as arsenic.

  The first conductivity type impurity layer 1 is formed in the photosensitive region 9. The first conductivity type impurity layer 1 is formed so as to be embedded in one surface of the second conductivity type impurity layer 2, and a silicon thermal oxide film 3 is formed on the surface. Here, the planar shape of the photosensitive region 9 is a substantially rectangular shape formed by two long sides and two short sides, and an electrode is formed on the surface of the silicon thermal oxide film 3 on the short side of the planar shape. 4 is formed, and an electrode 5 is formed on the surface of the second conductivity type impurity layer 2 opposite to the surface. The electrode 5 is electrically connected to the second conductivity type impurity layer 2. Between the electrode 4 and the first conductivity type impurity layer 1, a contact portion 6 a for penetrating the silicon thermal oxide film 3 and electrically connecting the electrode 4 and the first conductivity type impurity layer 1. Is formed.

  In addition, a contact portion 6b is formed through the silicon thermal oxide film 3 on the short side located on the opposite side of the electrode 4 of the two short sides forming the planar shape of the photosensitive region 9, and the contact portion 6b The first conductive type impurity layer 1 is electrically connected. The contact portions 6 (6a, 6b) are electrically connected to each other through the conductor portion 7.

  The conducting wire portion 7 is formed to be parallel to the surface of the photosensitive region 9 and along a single straight line extending in the long side direction at the approximate center of the surface. Further, as described above, the lead wire portion 7 electrically connects the contact portions 6 (6a, 6b) to each other, but may be configured to be directly connected to the electrode 4 as well.

  Here, the contact portion 6 (6a, 6b) and the conductor portion 7 are made of a material (polysilicon, metal, etc.) having a smaller electrical resistance than the first conductivity type impurity layer 1. In particular, the contact portion 6 may be made of the same material as that of the conductor portion 7. In this case, the contact portion 6 (6 a, 6 b) is integrally formed with the conductor portion 7. Furthermore, the contact part 6 (6a, 6b), the conducting wire part 7, and the electrode 4 may be integrally formed of the same substance.

  Further, a light shielding film 8 is formed for each interval between the photodiodes 10 arranged in parallel. In this case, the light shielding film 8 is between the photosensitive regions 9 arranged in parallel, covers the outer periphery of the planar shape of each photosensitive region 9 (long side in the present embodiment), and the vicinity of the outer periphery in the planar shape. It is formed on the surface of the silicon thermal oxide film 3 in a shape that blocks incident light.

  In the photodiode 10 having the above configuration, when light is incident on the photosensitive region 9 with a voltage applied between the electrodes 4 and 5, a depletion layer in the first conductivity type impurity layer 1 constituting the photosensitive region 9 is used. Career is generated. The carriers reach the electrode 4 through the first conductivity type impurity layer 1, the contact portion 6 (6 a, 6 b), and the conducting wire portion 7, and carrier charges are extracted by the electrode 4.

  However, since the carrier moving speed is faster in the contact portion 6 (6a, 6b) and the conductor portion 7 than in the first conductivity type impurity layer 1 (lower electrical resistance than in the first conductivity type impurity layer 1), Carriers generated in the first conductivity type impurity layer 1 mainly move through the contact portions 6 (6a, 6b) and the conductive wire portion 7 and reach the electrode 4. Thereby, the moving speed of the carriers becomes faster than the case of moving only in the first conductivity type impurity layer 1, and the light response speed is improved.

  Furthermore, since the photosensitive region 9 is configured by the first conductivity type impurity layer 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.

In general, in a photodiode formed by forming the first conductivity type impurity layer 1 in the second conductivity type impurity layer 2, as shown in FIG. 12, a semiconductor layer 46 (photosensitive region 42) or a semiconductor layer 47 is formed. In the vicinity of the interface between the Si layer containing Si and the SiO ₂ layer 48 formed on the surface of the Si layer, dark current (noise) due to electron-pair defects of molecular bonds is generated. When in contact with the depletion layer, an electric charge is generated in the SiO ₂ layer 48 in response to incident light, and the dark current resulting from the above-described molecular bond electron pair defects is further increased and increased. Therefore, when the impurity concentration of the semiconductor layer 46 (photosensitive region 42) is set low, the depletion layer also expands in the semiconductor layer 46, so that the dark current generated in the semiconductor layer 46 in response to incident light is also increased. This increases the noise and increases the noise. On the other hand, in the photodiode array according to the present embodiment, the vicinity of the outer periphery in the planar shape of the photosensitive region 9 is covered by the light-shielding film 8, so that the increase in the dark current according to the incident light as described above can be suppressed. become. In the present embodiment, the light shielding film 8 covers only the long side of the photosensitive region 9, but it may have a shape covering the entire outer periphery including the short side, which increases the dark current. Can be suppressed more effectively, which is preferable.

  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 9 are adjacent to each other. It is arranged in parallel. In this case, the electrode 4 for extracting the carrier charges generated in the photodiode 10 is arranged on one short side in the planar shape of the photosensitive region 9 so that as many photodiodes 10 as possible can be arranged at high density. Each is provided.

  FIG. 2 shows four types of photodiode arrays having the above basic configuration. FIGS. 2A to 2D are all plan views showing the photodiode array according to the present embodiment.

  The photodiode array 21 shown in FIG. 2A 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 9. These are arranged in parallel on the surface of 20a. The photodiode array 22 shown in FIG. 2B is also of a monolithic type, and a plurality of photodiodes 10 connected to the shift register 20b are arranged so that the long sides forming the planar shape of the photosensitive region 9 are adjacent to each other. A plurality of rows (two rows in the example shown in FIG. 2) arranged in parallel on the surface of the substrate 20a are provided. The photodiode array 23 shown in FIG. 2C 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 9. 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. 2D has a separate chip structure, but has a plurality of substrates 20a (two in the example shown in FIG. 2), and the surface of each substrate 20a is read out. A plurality of photodiodes 10 connected to the circuit 20c are arranged in parallel in a row so that the long sides forming the planar shape of the photosensitive region 9 are adjacent to each other.

  Here, the monolithic type includes a shift register 20b on a substrate 20a, and the shift register 20b can output the amount of light received by the photodiode 10 as digital 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.

  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.

  Next, the spectrometer 30 according to the present embodiment will be described with reference to FIG. FIG. 3 is a perspective view showing the spectrometer according to the present embodiment.

  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.

  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 is a dark current (low noise) and has high photosensitivity and fast photoresponse speed, it becomes a highly accurate spectrometer having high wavelength resolution.

  The present invention is not limited to the photodiode arrays 21 to 24 and the photodiode 10 according to the present embodiment, and the detailed configuration and detailed operation thereof can be changed.

  For example, photodiodes 10a to 10f shown in FIGS. 4 to 9 may be used in place of the photodiode 10. 4 to 9 are diagrams showing first to sixth modifications of the photodiode according to the present embodiment, respectively.

  <First Modification> FIG. 4A is a plan view showing a photodiode as a first modification according to the present embodiment, and FIG. 4B is a cross-sectional view taken along the line II-II shown in FIG. It is a figure which shows the cross-section of an arrow direction. In the photodiode 10a shown in FIG. 4, in addition to the contact parts 6a and 6b, a plurality of other contact parts 6 (two in the example shown in FIG. 4) are provided between the contact parts 6a and 6b. Except for, the configuration of the photodiode 10a is the same as that of the photodiode 10 shown in FIG.

  In the photodiode 10a, the contact portions 6 (6a, 6b) both penetrate the silicon thermal oxide film 3 to electrically connect the conductive wire portion 7 and the first conductivity type impurity layer 1, and the contact portions 6 (6a, 6b) are electrically connected. 6b) is electrically connected in series via the conductor portion 7.

  In the photodiode 10a, in addition to the contact portions 6 (6a, 6b), more contact portions 6 are provided, so that the electrode 4 is connected via the contact portions 6 (6a, 6b) and the conductor portion 7 having a low electrical resistance. This further increases the number of carriers that can reach the wavelength, thereby improving the optical response speed. In addition, the number of the contact parts 6 provided between the contact part 6a and the contact part 6b should just be one or more, and is not restricted to two.

  <Second Modification> FIG. 5A is a plan view showing a photodiode as a second modification according to the present embodiment, and FIG. 5B is a cross-sectional view taken along the line III-III shown in FIG. It is a figure which shows the cross-section of an arrow direction. In the photodiode 10b shown in FIG. 5, in addition to the contact portions 6a and 6b, a plurality of other contact portions 6 are provided on each of the two long sides in the planar shape of the photosensitive region 9 (two in the example shown in FIG. 5). Except for this point, the configuration of the photodiode 10b is the same as that of the photodiode 10 shown in FIG.

  In the photodiode 10b, since each contact portion 6 (6a, 6b) is electrically connected in series via the conductor portion 7 on each long side, more contacts in addition to the contact portions 6a, 6b. The part 6 is provided on each of the two long sides (that is, over a wider range of the photosensitive region 9). For this reason, the number of carriers that can reach the electrode 4 via the contact portion 6 (6a, 6b) and the conductive wire portion 7 having low electrical resistance further increases, and the optical response speed is improved. In addition, the number of the contact parts 6 formed in each long side should just be one or more, and is not restricted to two. Here, the conducting wire portion 7 is formed along each of two straight lines extending in the long side direction parallel to the surface of the photosensitive region 9 on each of the two long sides in the planar shape. ing.

  <Third Modification> FIG. 6A is a plan view showing a photodiode as a third modification according to the present embodiment, and FIG. 6B is an IV-IV shown in FIG. It is a figure which shows the cross-section of an arrow direction. A photodiode 10c shown in FIG. 6 realizes a function for electrically connecting the electrode 4 and the contact portion 6 (6a, 6b) with a low resistance in place of the conductor portion 7 in the light shielding film. . That is, the photodiode 10c is provided with a light-shielding film 8a in which both are integrated in place of the conductive wire portion 7 and the light-shielding film 8 of the photodiode 10 described above. Except for this point, the configuration of the photodiode 10c is the photodiode 10c. It has become the same thing.

  The light shielding film 8a is made of an electrically low resistance metal or polysilicon. The light shielding film 8a is electrically connected to the contact portion 6 (6a, 6b) and the electrode 4 provided on each of the two short sides in the planar shape of the photosensitive region 9, and this plane One of the two long sides forming the shape and the long side of the other photodiode 10c adjacent to the long side are covered together, and the vicinity of the two long sides in the planar shape of the photosensitive region 9 is covered. At the same time, it is formed on the surface of the silicon thermal oxide film 3 so as to be shielded from light. Note that the plurality of light shielding films 8a formed in each photosensitive region 9 are not electrically connected, and are electrically independent from each other.

  In the photodiode 10c, carriers generated by incident light can reach the electrode 4 through the contact portion 6 (6a, 6b) having a lower electrical resistance than the first conductivity type impurity layer 1 and the light shielding film 8a. The speed is improved.

  In the photodiode 10c, the light-shielding film 8a has a light-shielding function for shielding incident light to the vicinity of the outer periphery in the planar shape of the photosensitive region 9, and an electrical connection between the electrode 4 and the contact portion 6 (6a, 6b). Therefore, it has a function for connecting with low resistance. Therefore, each function can be realized only by the light shielding film 8a without using separate components (for example, the conductive wire portion 7 and the light shielding film 8). Thereby, reduction of manufacturing cost and a manufacturing process is achieved.

  <Fourth Modification> FIG. 7A is a plan view showing a photodiode as a fourth modification according to the present embodiment, and FIG. 7B is a VV shown in FIG. 7A. It is a figure which shows the cross-section of an arrow direction. Similarly to the photodiode 10c, the photodiode 10d shown in FIG. 7 has a configuration in which the electrode 4 and the contact portion 6 (6a, 6b) are electrically connected by an electrically low-resistance light-shielding film. In the photodiode 10d shown in FIG. 6, in addition to the contact portions 6a and 6b, a plurality of other contact portions 6 are provided on one long side in the planar region of the photosensitive region 9 (shown in FIG. 7). Except for this point, the configuration of the photodiode 10d is the same as that of the photodiode 10c. In addition, the number of the contact parts 6 provided in each long side should just be one or more, and is not restricted to three. The plurality of light shielding films 8a formed in each photosensitive region 9 are not electrically connected and are electrically independent from each other.

  In the photodiode 10d, carriers generated by incident light can reach the electrode 4 through the contact portion 6 (6a, 6b) having a lower electrical resistance than the first conductivity type impurity layer 1 and the light shielding film 8a. The speed is improved. In the photodiode 10d, more contact portions 6 are provided in addition to the contact portions 6a and 6b. Therefore, a larger amount of the contact portions 6 (6a and 6b) and the light shielding film 8a have a lower electrical resistance. Carriers can reach the electrode 4. For this reason, the optical response speed can be further improved.

  In the photodiode 10d, the light shielding film 8a has a light shielding function for shielding incident light to the vicinity of the outer periphery in the planar shape of the photosensitive region 9, and an electrical connection between the electrode 4 and the contact portion 6 (6a, 6b). Therefore, it has a function for connecting with low resistance. Therefore, each function can be realized only by the light shielding film 8a without using separate components (for example, the conductive wire portion 7 and the light shielding film 8). Thereby, reduction of manufacturing cost and a manufacturing process is achieved.

  <Fifth Modification> FIG. 8A is a plan view showing a photodiode as a fifth modification according to the present embodiment, and FIG. 8B is a VI-VI shown in FIG. It is a figure which shows the cross-section of an arrow direction. Similarly to the photodiode 10c, the photodiode 10e shown in FIG. 8 has a configuration in which the electrode 4 and the contact portion 6 (6a, 6b) are electrically connected by a light-shielding film having low electrical resistance. In this photodiode 10e, a light shielding film 8b is provided on the surface of the silicon thermal oxide film 3 so as to cover the planar outer periphery of the photosensitive region 9, and in addition to the contact parts 6a and 6b, another contact part 6 is provided. However, a plurality (three in the example shown in FIG. 8) are provided on each of the two long sides in the planar shape. In addition, the number of the contact parts 6 provided in each long side should just be one or more, and is not restricted to three. The plurality of light shielding films 8b formed for each photosensitive region 9 are not electrically connected, and are electrically independent from each other.

  In the photodiode 10e, carriers generated by incident light can reach the electrode 4 through the contact portion 6 (6a, 6b) having a lower electrical resistance than the first conductivity type impurity layer 1 and the light shielding film 8b. The speed is improved. In the photodiode 10e, in addition to the contact portions 6a and 6b, a larger number of contact portions 6 are provided over a wider region of the photosensitive region 9 (two long sides in the planar shape of the photosensitive region 9). Therefore, more carriers can reach the electrode 4 through the contact portion 6 (6a, 6b) having a low electrical resistance and the light shielding film 8b. For this reason, the optical response speed can be further improved.

  In the photodiode 10e, the light-shielding film 8b has a light-shielding function for shielding the incident light to the vicinity of the outer periphery in the planar shape of the photosensitive region 9, and the electrical connection between the electrode 4 and the contact portion 6 (6a, 6b). Therefore, it has a function for connecting with low resistance. Therefore, each function can be realized only by the light shielding film 8b without using separate components (for example, the conductive wire portion 7 and the light shielding film 8). Thereby, reduction of manufacturing cost and a manufacturing process is achieved.

  In the photodiodes 10c, 10d, and 10e, the contact portions 6 (6a and 6b) and the light shielding films 8a and 8b may be made of the same substance (for example, metal or polysilicon) having a small electric resistance. In this case, the contact portion 6 (6a, 6b) is integrally formed with the light shielding films 8a, 8b.

  <Sixth Modification> Further, the contact portion 6 (6a, 6b) and the light shielding films 8a, 8b are the same electric conductor (metal), in particular, the same material as the electrode 4 (for example, metal, polysilicon, etc.) This case will be described below as a sixth modification. FIG. 9A is a plan view showing a photodiode as a sixth modification according to the present embodiment, and FIG. 9B shows a cross-sectional structure in the direction of the arrow VII-VII shown in FIG. FIG. The photodiode 10f shown in FIG. 9 is provided with a light shielding film integrally formed with an electrode for extracting carrier charges, and the light shielding film and the contact portion 6 (6a, 6b) are electrically connected. Yes. That is, in the photodiode 10f, the electrode 4a is provided in place of the electrode 4 and the light-shielding film 8a included in the photodiode 10c described above. Except for this point, the configuration of the photodiode 10f is the same as that of the photodiode 10c. Yes.

  The electrode 4a is made of an electrically low resistance metal or polysilicon. The electrode 4a is electrically connected to the contact portions 6 (6a, 6b) provided on each of the two short sides in the planar shape of the photosensitive region 9, and two electrodes that form this planar shape. One of the long sides and the long side of the other photodiode 10c adjacent to the long side are covered together, and the vicinity of the two long sides in the planar shape of the photosensitive region 9 is shielded simultaneously. Formed on the surface of the silicon thermal oxide film 3 in shape. Note that the plurality of electrodes 4a formed in each photosensitive region 9 are not electrically connected, and are electrically independent from each other.

  In the photodiode 10f, carriers generated by incident light can directly reach the electrode 4a via the contact portion 6 (6a, 6b) having a lower electrical resistance than that of the first conductivity type impurity layer 1, thereby improving the optical response speed. Figured.

  In the photodiode 10f, the electrode 4a has a function for extracting the carrier charge generated by the incident light, a light shielding function for shielding the incident light to the vicinity of the outer periphery in the planar shape of the photosensitive region 9, and the electrode. The contact portion 6 (6a, 6b) has a function of electrically connecting with a low resistance. Therefore, each function can be realized only by the electrode 4a without using separate components (for example, the electrode 4, the conductor portion 7, and the light shielding film 8). Thereby, reduction of manufacturing cost and a manufacturing process is achieved.

  The contact portion 6 (6a, 6b) may not be the same material as the electrode 4a as long as it has a lower electrical resistance than the first conductivity type impurity layer 1.

  In the photodiode 10d described above, the electrode 4a may be used in place of the electrode 4 and the light shielding film 8a. In the photodiode 10e described above, the electrode 4a is integrally formed with the electrode instead of the electrode 4 and the light shielding film 8b. Similar to the light shielding film 8b, a light shielding film (not shown) having a shape covering the planar outer periphery of the photosensitive region 9 may be used. In this case, in addition to the contact portions 6 (6a, 6b), more contact portions 6 are provided over a wide region of the photosensitive region 9 (two long sides in the planar shape of the photosensitive region 9). Therefore, the light response speed can be further improved.

  In the photodiodes 10, 10a to 10f described above, the film formed on the surface of the photosensitive region is a silicon thermal oxide film, but is not limited thereto. For example, a silicon nitride film formed by CVD or a composite film of a silicon thermal oxide film and a silicon nitride film may be used.

It is a figure which shows the photodiode which concerns on this embodiment. It is a top view which shows the photodiode array which concerns on this embodiment. It is a perspective view which shows the spectrometer which concerns on this embodiment. It is a figure which shows the 1st modification of the photodiode which concerns on this embodiment. It is a figure which shows the 2nd modification of the photodiode which concerns on this embodiment. It is a figure which shows the 3rd modification of the photodiode which concerns on this embodiment. It is a figure which shows the 4th modification of the photodiode which concerns on this embodiment. It is a figure which shows the 5th modification of the photodiode which concerns on this embodiment. It is a figure which shows the 6th modification of the photodiode which concerns on this embodiment. It is a top view which shows the conventional photodiode array. It is a top view which shows the conventional photodiode. It is a figure for demonstrating the depletion layer which arises in the conventional photodiode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st conductivity type impurity layer, 2 ... 2nd conductivity type impurity layer, 3 ... Silicon thermal oxide film, 4, 4a, 5 ... Electrode, 6, 6a, 6b ... Contact , 7... Conducting wire part, 8, 8 a, 8 b... Light shielding film, 9 .. photosensitive region, 10, 10 a to 10 f... Photodiode, 20 a. 20d ... wire, 20b ... shift register, 21-24 ... photodiode array, 30 ... spectrometer, 31 ... optical fiber, 32 ... incident part, 33 ... diffraction grating part 34 ... Mirror, 35 ... Base, 36 ... Light detection means.

Claims (7)

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, an electrode for extracting charges generated by light incident on the photosensitive region, and provided on one short side in the planar shape of the photosensitive region. A conductive wire part electrically connected; and a plurality of contact parts for electrically connecting the conductive wire part and the electrode to the photodiode;
The photodiode includes a first semiconductor layer containing a first conductivity type impurity and a first semiconductor layer constituting the photosensitive region in a second semiconductor layer containing an impurity of a second conductivity type different from the first conductivity type. while being formed, it is electrically connected to the first semiconductor layer and the plurality of contact portions through respectively the silicon thermal oxide film on the first semiconductor layer,
The photodiode array according to claim 1, wherein the contact portion and the conductive wire portion are made of a material having an electric resistance smaller than that of the first semiconductor layer.   The conducting wire portion is made of a material capable of blocking incident light, and is formed in a shape that covers part or all of the vicinity of the outer periphery in the planar shape of the photosensitive region with respect to the incident light. The photodiode array according to claim 1.   3. The photodiode array according to claim 1, wherein the contact portion and the conductor portion are integrally formed of the same material. 4.   3. The photodiode array according to claim 1, wherein the electrode, the conducting wire portion, and the contact portion are integrally formed of the same material.   5. The photodiode array according to claim 1, wherein the contact portion is provided on at least two short sides in a planar shape of the photosensitive region. 6.   The contact portion is provided with one or a plurality of one or both of the two long sides in the planar shape of the light sensitive region, respectively. 6. Photodiode array according to. A spectroscope comprising: a spectroscopic unit that splits incident light; and the photodiode array according to any one of claims 1 to 6 that converts an amount of incident light after splitting into an electric signal.

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