Spectrometer

Abstract

In the present invention, a light detection part of a light detection element has a first light detection region, a second light detection region, and a third light detection region. A spectroscopic unit causes light in a first wavelength range to be incident on the first light detection region, causes light in a second wavelength range at wavelengths longer than the first wavelength range to be incident on the second light detection region, and causes light in a third wavelength range at wavelengths longer than the second wavelength range to be incident on the third light detection region. A coverage ratio of a silicon nitride film in the third light detection region is higher than a coverage ratio of the silicon nitride film in the first light detection region. A coverage ratio of the silicon nitride film in the second light detection region is higher than or equal to the coverage ratio of the silicon nitride film in the first light detection region and lower than or equal to the coverage ratio of the silicon nitride film in the third light detection region.

Description

spectrometer 【0001】 This disclosure relates to a spectrometer. 【0002】 Patent Document 1 describes a spectroscopic apparatus comprising a dispersion element for dispersing composite light, a detector for detecting the light intensity at each wavelength of light dispersed by the dispersion element, and a plurality of optical filters positioned directly in front of the detector, wherein the plurality of optical filters are joined to each other via a bonding surface formed obliquely to the arrangement direction of the detection elements constituting the detector. In the spectroscopic apparatus described in Patent Document 1, the plurality of optical filters are used to transmit diffracted light of a predetermined order and cut out higher-order diffracted light of the diffracted light of that predetermined order. 【0003】 Japanese Patent Publication No. 2005-156343 【0004】 However, in the spectrometer described in Patent Document 1, the overall size reduction is limited because multiple optical filters are made of glass or the like. Also, in the spectrometer described in Patent Document 1, visible light is assumed as the diffracted light of a predetermined order, but if the diffracted light of a predetermined order is ultraviolet light, special materials must be prepared as optical filters. 【0005】 Therefore, the purpose of this disclosure is to provide a spectrometer that can appropriately detect diffracted light of a predetermined order when the diffracted light of a predetermined order is ultraviolet light, while miniaturizing the overall size. 【0006】A spectrometer in one aspect of the present disclosure comprises: [1] a spectrometer that spectrally analyzes and reflects measurement light; a photodetector that detects diffracted light of a predetermined order spectrally analyzed by the spectrometer from the measurement light reflected by the spectrometer; and a photodetector having a silicon nitride film disposed on the light-receiving surface of the photodetector, wherein the photodetector has a first photodetector region including at least one first pixel, a second photodetector region including at least one second pixel, and a third photodetector region including at least one third pixel, and when viewed from a first direction in which the measurement light is incident on the spectrometer, the second photodetector region is disposed between the first photodetector region and the third photodetector region in a second direction intersecting the first direction. The spectrometer is a spectrometer in which the diffracted light in a first wavelength range is incident on the first photodetection region, the diffracted light in a second wavelength range that is longer than the first wavelength range is incident on the second photodetection region, and the diffracted light in a third wavelength range that is longer than the second wavelength range is incident on the third photodetection region, the coverage rate of the silicon nitride film in the third photodetection region is greater than the coverage rate of the silicon nitride film in the first photodetection region, the coverage rate of the silicon nitride film in the second photodetection region is greater than or equal to the coverage rate of the silicon nitride film in the first photodetection region, and less than or equal to the coverage rate of the silicon nitride film in the third photodetection region. 【0007】In the spectrometer described above, a silicon nitride film having the characteristic of changing transmittance in the ultraviolet wavelength range is placed on the light-receiving surface of the photodetector. This allows the silicon nitride film to function as a filter for ultraviolet light in the photodetector element, thereby enabling a reduction in overall size. Furthermore, the coverage rate of the silicon nitride film in the third photodetector region, where light in the third wavelength range (longer wavelengths than the first and second wavelength ranges) is incident, is greater than the coverage rate of the silicon nitride film in the first photodetector region, where light in the first wavelength range is incident. As a result, when diffracted light of a predetermined order is ultraviolet light, the silicon nitride film can cut off the higher-order diffracted light of the first wavelength range and the higher-order diffracted light of the wavelength range shorter than the first wavelength range, thereby suppressing the incidence of these higher-order diffracted lights into the third photodetector region. Furthermore, the coverage of the silicon nitride film in the second photodetection region, where light in the second wavelength range (longer than the first wavelength range) is incident, is greater than or equal to the coverage of the silicon nitride film in the first photodetection region, where light in the first wavelength range is incident, and less than or equal to the coverage of the silicon nitride film in the third photodetection region, where light in the third wavelength range (longer than the second wavelength range) is incident. This makes it possible to suppress a sharp decrease in sensitivity within the second photodetection region when the diffracted light of a predetermined order is ultraviolet light. As a result, the above spectrometer can appropriately detect diffracted light of a predetermined order when it is ultraviolet light, while miniaturizing the overall size. 【0008】 One aspect of the present disclosure may be [2] "the spectrometer described in [1] above, wherein the thickness of the silicon nitride film is 190 nm or more and 400 nm or less." With this spectrometer, diffracted light of a predetermined order, which is ultraviolet light, can be detected more appropriately. 【0009】A spectrometer in one aspect of the present disclosure may be [3] "the spectrometer according to [1] or [2] above, wherein the second photodetector region includes a plurality of second pixels arranged in the second direction, the second wavelength range is included in the wavelength range of light in which the transmittance to the silicon nitride film is 5% or more and 80% or less, and the coverage of the silicon nitride film in the second photodetector region increases as it approaches the third photodetector region." With this spectrometer, it is possible to reliably suppress a sharp decrease in sensitivity within the second photodetector region when the diffracted light of a predetermined order is ultraviolet light. 【0010】 A spectrometer in one aspect of the present disclosure may be [4] "a spectrometer according to any one of [1] to [3] above, wherein the photodetector further comprises an insulating film disposed between the light-receiving surface and the silicon nitride film, a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface, and the silicon nitride film is formed along the surface of the insulating film." According to this spectrometer, when diffracted light is incident on the light-receiving surface of the photodetector, a plurality of interferences with different optical path lengths occur within the insulating film, causing the periods of variation in spectral sensitivity with respect to the wavelength of the diffracted light to cancel each other out, thereby reducing sensitivity variation in the wavelength range of the diffracted light. 【0011】 A spectrometer in one aspect of the present disclosure may be [5] "a spectrometer according to any one of [1] to [3] above, wherein the photodetector further comprises an insulating film disposed on the light-receiving surface, the silicon nitride film is disposed between the light-receiving surface and the insulating film, and a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface." According to this spectrometer, when diffracted light is incident on the light-receiving surface of the photodetector, multiple interferences with different optical path lengths occur within the insulating film, causing the periods of variation in spectral sensitivity with respect to the wavelength of the diffracted light to cancel each other out, thereby reducing sensitivity variation in the wavelength range of the diffracted light. 【0012】A spectrometer in one aspect of the present disclosure may be [6] "the spectrometer according to [4] or [5] above, wherein the insulating film is a BPSG film, a PSG film, or an SOG film." With such a spectrometer, an insulating film having a surface on which a plurality of irregularities are formed can be easily and reliably formed. 【0013】 A spectrometer in one aspect of this disclosure may be [7] "a spectrometer according to any one of [1] to [6] above, wherein the coverage of the silicon nitride film in the first photodetection region is 0%, the coverage of the silicon nitride film in the second photodetection region is 25% or more and 75% or less, and the coverage of the silicon nitride film in the third photodetection region is 100%." ​​With such a spectrometer, diffracted light of a predetermined order, which is ultraviolet light, can be detected more appropriately. 【0014】 A spectrometer in one aspect of the present disclosure comprises: [8] a spectrometer that spectrally analyzes and reflects a measurement light; a photodetector that detects diffracted light of a predetermined order spectrally analyzed by the spectrometer from the measurement light reflected by the spectrometer; and a photodetector having a silicon nitride film disposed on the light-receiving surface of the photodetector, wherein the photodetector comprises: a first photodetector region including at least one first pixel; a second photodetector region including at least one second pixel; and a third photodetector region including at least one third pixel, and when viewed from a first direction in which the measurement light is incident on the spectrometer, The second photodetector is positioned between the first and third photodetector in a second direction intersecting the first direction, the spectrometer is configured to incident light in a first wavelength range from the diffracted light onto the first photodetector, light in a second wavelength range longer than the first wavelength range onto the second photodetector, and light in a third wavelength range longer than the second wavelength range onto the third photodetector, and the silicon nitride film does not cover the first photodetector but covers the third photodetector. 【0015】In the above spectrometer, a silicon nitride film having the characteristic of changing transmittance in the ultraviolet wavelength range is placed on the light-receiving surface of the photodetector. This allows the silicon nitride film to function as a filter for ultraviolet light in the photodetector element, thus enabling a reduction in overall size. Furthermore, the third photodetector region, to which light in the third wavelength range (longer wavelengths than the first and second wavelength ranges) is incident, is covered by the silicon nitride film, while the first photodetector region, to which light in the first wavelength range is incident, is not covered by the silicon nitride film. As a result, when diffracted light of a predetermined order is ultraviolet light, the silicon nitride film can cut off the higher-order diffracted light of the first wavelength range and the higher-order diffracted light of the wavelength range shorter than the first wavelength range, thereby suppressing the incidence of these higher-order diffracted lights into the third photodetector region. Thus, the above spectrometer enables appropriate detection of diffracted light of a predetermined order when it is ultraviolet light, while simultaneously achieving a reduction in overall size. 【0016】 A spectrometer in one aspect of this disclosure may be [9] "the spectrometer described in [8] above, wherein the thickness of the silicon nitride film is 190 nm or more and 400 nm or less." With this spectrometer, diffracted light of a predetermined order, which is ultraviolet light, can be detected more appropriately. 【0017】 A spectrometer in one aspect of the present disclosure may be

[10] "the spectrometer according to [8] or [9] above, wherein the second photodetector region includes a plurality of second pixels arranged in the second direction, the second wavelength range is included in the wavelength range of light in which the transmittance to the silicon nitride film is 5% or more and 80% or less, and the coverage of the silicon nitride film in the second photodetector region increases as it approaches the third photodetector region." With this spectrometer, it is possible to reliably suppress a sharp decrease in sensitivity within the second photodetector region when the diffracted light of a predetermined order is ultraviolet light. 【0018】A spectrometer in one aspect of the present disclosure may be

[11] "a spectrometer according to any one of [8] to

[10] above, wherein the photodetector further comprises an insulating film disposed between the light-receiving surface and the silicon nitride film, a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface, and the silicon nitride film is formed along the surface of the insulating film." According to this spectrometer, when diffracted light is incident on the light-receiving surface of the photodetector, a plurality of interferences with different optical path lengths occur within the insulating film, causing the periods of variation in spectral sensitivity with respect to the wavelength of the diffracted light to cancel each other out, thereby reducing sensitivity variation in the wavelength range of the diffracted light. 【0019】 A spectrometer in one aspect of the present disclosure may be

[12] "a spectrometer according to any one of [8] to

[10] above, wherein the photodetector further comprises an insulating film disposed on the light-receiving surface, the silicon nitride film is disposed between the light-receiving surface and the insulating film, and a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface." According to this spectrometer, when diffracted light is incident on the light-receiving surface of the photodetector, multiple interferences with different optical path lengths occur within the insulating film, causing the periods of variation in spectral sensitivity with respect to the wavelength of the diffracted light to cancel each other out, thereby reducing sensitivity variation in the wavelength range of the diffracted light. 【0020】 A spectrometer in one aspect of the present disclosure may be

[13] "the spectrometer according to

[11] or

[12] above, wherein the insulating film is a BPSG film, a PSG film, or an SOG film." With this spectrometer, an insulating film having a surface on which a plurality of irregularities are formed can be easily and reliably formed. 【0021】 A spectrometer in one aspect of the present disclosure may be

[14] "a spectrometer according to any one of [8] to

[13] above, wherein the coverage of the silicon nitride film in the first photodetection region is 0%, the coverage of the silicon nitride film in the second photodetection region is 25% or more and 75% or less, and the coverage of the silicon nitride film in the third photodetection region is 100%." ​​With such a spectrometer, diffracted light of a predetermined order, which is ultraviolet light, can be detected more appropriately. 【0022】 According to this disclosure, it is possible to provide a spectrometer that can appropriately detect diffracted light of a predetermined order when the diffracted light of a predetermined order is ultraviolet light, while miniaturizing the overall size. 【0023】 Figure 1 is a cross-sectional view of an example spectrometer. Figure 2 is a cross-sectional view of the spectrometer along the line II-II shown in Figure 1. Figure 3 is a side view of the photodetector and spectrometer shown in Figure 1. Figure 4 is a bottom view of the first photodetector of the photodetector shown in Figure 1. Figure 5 is a cross-sectional view of the first photodetector region of the first photodetector shown in Figure 4. Figure 6 is a cross-sectional view of the third photodetector region of the first photodetector shown in Figure 4. Figure 7 is a graph showing the transmittance characteristics of the silicon nitride film shown in Figure 4, and a graph showing the sensitivity characteristics of the first and third photodetector regions shown in Figure 4. Figure 8 is a graph showing the transmittance characteristics of the silicon nitride film shown in Figure 4. Figure 9 is a graph showing the characteristics of stray light emission and sensitivity for a comparative example, and for Example 1. Figure 10 is a graph showing the characteristics of stray light emission and sensitivity for Example 2, and for Example 3. Figure 11 is a graph showing the transmittance characteristics of the silicon nitride film shown in Figure 4. Figure 12 is a cross-sectional view of the third photodetection region of the modified first photodetector. 【0024】 An example of this disclosure will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted. [Spectrometer Configuration] 【0025】As shown in Figures 1 and 2, the spectrometer 1 comprises a photodetector 2, a spectral section 3, and a plurality of support members 4 and 5. The photodetector 2 has a light-passing section 2a through which the measurement light L passes. The spectral section 3 spectrally analyzes and reflects the measurement light L that has passed through the light-passing section 2a. The support member 4 supports the spectral section 3. The support member 5 is arranged on the support member 4 and supports the photodetector 2. Hereinafter, the direction in which the measurement light L is incident on the spectral section 3 will be referred to as the Z-axis direction (first direction). Also, one direction perpendicular to the Z-axis direction will be referred to as the X-axis direction (second direction intersecting the first direction), and the direction perpendicular to both the Z-axis direction and the X-axis direction will be referred to as the Y-axis direction. 【0026】 The photodetector 2, the spectroscopic unit 3, and the multiple support members 4 and 5 are housed in a package 6. The package 6 has a stem 61 and a cap 62. The stem 61 is formed, for example, from metal in the shape of a rectangular plate. The cap 62 is formed, for example, from metal in the shape of a rectangular parallelepiped box. The stem 61 and the cap 62 are airtightly joined at the flange portion 61a of the stem 61 and the flange portion 62a of the cap 62. The length of one side of the package 6 is, for example, about 10 to 20 mm. Note that the stem 61 and the cap 62 do not necessarily have to be joined to an airtight seal. 【0027】 A light-entry aperture 62c is formed in the wall portion 62b of the cap 62 that faces the stem 61 in the Z-axis direction, allowing measurement light L to enter the package 6 from outside. The shape of the light-entry aperture 62c when viewed from the Z-axis direction is, for example, circular. A window member 63 is hermetically joined to the inner surface of the wall portion 62b so as to cover the light-entry aperture 62c. The window member 63 transmits the measurement light L. The window member 63 is formed, for example, from glass in the shape of a circular or rectangular plate. The window member 63 may be coated with an AR (Anti-Reflection) coating. The window member 63 may have a filter function that transmits only light of a predetermined wavelength. Note that the cap 62 and the window member 63 do not need to be joined in a completely hermetically sealed manner. 【0028】Multiple lead pins 7 are fixed to the stem 61. Multiple through holes 61b are formed in the stem 61, and each lead pin 7 extends in the Z-axis direction through each through hole 61b. Each lead pin 7 is fixed to each through hole 61b via a hermetic sealing member (for example, low-melting-point glass having electrical insulation and light-shielding properties). The multiple through holes 61b are aligned along each of a pair of edges of the stem 61 that face each other in the Y-axis direction. 【0029】 The support member 4 is positioned on the inner surface 61c of the stem 61. The support member 4 has a surface 4a on the window member 63 side and a surface 4b on the stem 61 side. Surface 4a of the support member 4 includes a concave curved surface 4c. Surface 4b of the support member 4 is in contact with the inner surface 61c of the stem 61, but is not fixed to the inner surface 61c of the stem 61. The support member 4 is formed in the shape of a rectangular plate from, for example, silicone, resin, ceramic, glass, or the like. 【0030】 The spectral section 3 is composed of a molded layer 31 and a reflective film 32. The molded layer 31 is formed in a film-like manner along the curved surface 4c of the support member 4. A grating pattern 3a is formed on the molded layer 31. The grating pattern 3a is, for example, a blazed grating pattern, a binary grating pattern, a holographic grating pattern, etc. The grating pattern 3a has a plurality of grating grooves aligned in the X-axis direction when viewed from the Z-axis direction. Each grating groove extends in the Y-axis direction when viewed from the Z-axis direction. The reflective film 32 is formed in a film-like manner along the grating pattern 3a. The molded layer 31 is formed, for example, by photocuring or thermocuring of a resin. The reflective film 32 is formed, for example, by metal deposition onto the grating pattern 3a. 【0031】The support member 5 has a top wall portion 51, a pair of side wall portions 52 and 53, and a pair of protrusions 54. The top wall portion 51 is positioned between the spectrometer 3 and the window member 63 in the Z-axis direction. The top wall portion 51 has a surface 51a on the spectrometer 3 side and a surface 51b on the window member 63 side. The pair of side wall portions 52 and 53 are positioned between the support member 4 and the top wall portion 51 and face each other in the X-axis direction. The pair of protrusions 54 protrude from the top wall portion 51 on both sides in the Y-axis direction. Each protrusion 54 extends in the X-axis direction. Each protrusion 54 has a surface 54a on the side opposite to the stem 61 and a surface 54b on the side of the stem 61. The surface 54a of each protrusion 54 is located on the same plane as the surface 51b of the top wall portion 51. The top wall portion 51, the pair of side wall portions 52 and 53, and the pair of protrusions 54 are integrally formed from, for example, resin, ceramic, or the like. 【0032】 A light-passing aperture 51c is formed in the top wall portion 51 to allow measurement light L to pass through. The shape of the light-passing aperture 51c when viewed from the Z-axis direction is, for example, rectangular. The light-passing aperture 51c faces the light-entry aperture 62c of the cap 62 in the Z-axis direction. The light-passing aperture 51c is widened toward the light-entry aperture 62c in the X-axis direction and the Y-axis direction, respectively. When viewed from the Z-axis direction, the light-entry aperture 62c encompasses the entirety of the light-passing aperture 51c. 【0033】The side wall portion 52 is located on one side of the spectrometer 3 in the X-axis direction. The side wall portion 53 is located on the other side of the spectrometer 3 in the X-axis direction. The width of the side wall portion 52 in the X-axis direction is greater than the width of the side wall portion 53 in the X-axis direction. A pair of protrusions 52b are provided on the inner surface 52a of the side wall portion 52. Each protrusion 52b extends in the Z-axis direction. A pair of protrusions 53b are provided on the inner surface 53a of the side wall portion 53. Each protrusion 53b extends in the Z-axis direction. The bottom surface 52c of the side wall portion 52 is fixed to the surface 4a of the support member 4, for example, by adhesive. The bottom surface 53c of the side wall portion 53 is in contact with the surface 4a of the support member 4, but is not fixed to the surface 4a of the support member 4. In the spectrometer 1, the support of the support member 5 on the support member 4 is stabilized by the pair of protrusions 52b and the pair of protrusions 53b. 【0034】 The photodetector 2 has a semiconductor substrate 20. The semiconductor substrate 20 is formed in the shape of a rectangular plate, for example, from silicon. The semiconductor substrate 20 has a surface 20a on which the first photodetector (photodetector) 21 and the second photodetector 22 are provided, and a surface 20b on the opposite side. Surface 20a of the semiconductor substrate 20 faces the spectral section 3 across space. Surface 20b of the semiconductor substrate 20 is fixed to the surface 51a of the top wall 51, for example, by adhesive. The photodetector 2 is electrically connected to wiring (not shown) provided on the support member 5 at the top wall 51. The photodetector 2 is, for example, a CMOS image sensor. The photodetector 2 may be other image sensors (for example, a CCD image sensor, etc.). 【0035】 The light-transmitting portion 2a is a slit formed in the semiconductor substrate 20. When viewed from the Z-axis direction, the shape of the light-transmitting portion 2a is, for example, a rectangle with the Y-axis direction as the longer side. The light-transmitting portion 2a is located between the light-transmitting aperture 51c of the top wall portion 51 and the spectral portion 3 in the Z-axis direction, and is adjacent to the light-transmitting aperture 51c of the top wall portion 51. The light-transmitting portion 2a is widened toward the light-transmitting aperture 51c in the X-axis direction and the Y-axis direction, respectively. When viewed from the Z-axis direction, the light-transmitting aperture 51c includes the entirety of the light-transmitting portion 2a. 【0036】 The first light detection unit 21 is arranged on the side of the side wall portion 53 in the X-axis direction with respect to the light passage portion 2a. The second light detection unit 22 is arranged on the side of the side wall portion 52 in the X-axis direction with respect to the light passage portion 2a. That is, when viewed from the Z-axis direction, the light passage portion 2a is arranged between the first light detection unit 21 and the second light detection unit 22 in the X-axis direction. The first light detection unit 21 detects the -1st order light (diffracted light of a predetermined order: m-th order diffracted light (m is an integer other than 0)) L1 in a predetermined wavelength range spectrally separated by the spectral separation unit 3 among the measurement lights L reflected by the spectral separation unit 3. The second light detection unit 22 detects the 0th order light L0 among the measurement lights L reflected by the spectral separation unit 3. Hereinafter, the -1st order light L1 in a predetermined wavelength range spectrally separated by the spectral separation unit 3 and detected by the first light detection unit 21 is simply referred to as "-1st order light L1". 【0037】 A plurality of through holes 54c are formed in each protruding portion 54. The plurality of through holes 54c are arranged side by side in the X-axis direction in each protruding portion 54. The end portions of each lead pin 7 are arranged in each through hole 54c, and a stopper 71 provided on each lead pin 7 is in contact with the surface 54b of each protruding portion 54. Thereby, the support members 4 and 5 fixed to each other are positioned with respect to the package 6. A predetermined number of lead pins 7 among the plurality of lead pins 7 are electrically connected to the wiring provided on the support member 5 in each protruding portion 54. 【0038】In the spectrometer 1 configured as described above, the measurement light L sequentially passes through the light incident aperture 62c of the package 6, the window member 63, the light passing aperture 51c of the top wall portion 51, and the light passing portion 2a of the light detection element 2 and enters the spectroscopic unit 3. Then, among the measurement light L reflected by the spectroscopic unit 3, the -1st order light L1 enters the first light detection unit 21 of the light detection element 2, and the incident -1st order light L1 is detected by the first light detection unit 21. On the other hand, among the measurement light L reflected by the spectroscopic unit 3, the 0th order light L0 enters the second light detection unit 22 of the light detection element 2, and the incident 0th order light L0 is detected by the second light detection unit 22. At this time, the input and output of the electrical signals to the first light detection unit 21 and the second light detection unit 22 are implemented via a predetermined number of lead pins 7 electrically connected to the wiring provided on the support member 5. As described above, for example, in an external processing device, based on the detection result obtained by the first light detection unit 21, the spectrum of the measurement light L in a predetermined wavelength range can be obtained. Further, for example, in an external processing device, based on the detection result obtained by the second light detection unit 22, correction of the relationship between the wavelength and the incident position of the -1st order light L1 incident on the first light detection unit 21, acquisition of at least one of the incident angle and the numerical aperture of the measurement light L incident on the spectroscopic unit 3 through the light passing portion 2a, acquisition of the diffraction efficiency of the spectroscopic unit 3, etc. can be implemented. 【0039】 In the spectrometer 1, the support members 4 and 5 fixed to each other are positioned with respect to the package 6 by a plurality of lead pins 7. And in the support members 4 and 5 fixed to each other, the surface 4b of the support member 4 only contacts the inner surface 61c of the stem 61 and is not fixed to the inner surface 61c of the stem 61, and the bottom surface 53c of the side wall portion 53 only contacts the surface 4a of the support member 4 and is not fixed to the surface 4a of the support member 4. Due to these, in the spectrometer 1, for example, even when deformation (expansion or contraction) of each part occurs due to a change in the environmental temperature, heat generation of the light detection element, etc., it is difficult for a deviation to occur in the relative positional relationship among the light passing portion 2a, the spectroscopic unit 3, the first light detection unit 21, and the second light detection unit 22. [-1st order light and relationship with higher order diffracted light] 【0040】 As shown in FIG. 3, the spectroscopic unit 3 is the light L1 in the first wavelength range among the -1st order light L1 ＳThe light is incident on the first light detection region 211, and the light L1 in the second wavelength range of the -1st order light L1 Ｍ The light is incident on the second photodetection region 212, and the light L1 in the third wavelength range of the -1st order light L1 Ｌ The light is incident on the third photodetection region 213. The second wavelength range is a wavelength range with longer wavelengths than the first wavelength range, and the third wavelength range is a wavelength range with longer wavelengths than the second wavelength range. The first photodetection region 211, the second photodetection region 212, and the third photodetection region 213 are a plurality of photodetection regions of the first photodetection unit 21. When viewed from the Z-axis direction, the second photodetection region 212 is located between the first photodetection region 211 and the third photodetection region 213 in the X-axis direction. The first photodetection region 211 is located on the light-passing portion 2a side relative to the second photodetection region 212, and the third photodetection region 213 is located on the opposite side of the light-passing portion 2a relative to the second photodetection region 212. The first photodetection region 211, the second photodetection region 212, and the third photodetection region 213 are continuous in the X-axis direction. 【0041】 As an example, in the first light detection unit 21, light L1 in the third wavelength range Ｌ In the third light detection region 213 where detection is to be performed, light L1 in the third wavelength range is present. Ｌ In addition, light L1 in the first wavelength range Ｓ -Second-order light and -second-order light from wavelength ranges shorter than the first wavelength range may be incident. Thus, if higher-order diffracted light such as -second-order light, in addition to -first-order light L1, is incident on the region where the first photodetector 21 is to detect -1st-order light L1, the noise in the detection result acquired by the first photodetector 21 may increase. To suppress such noise and appropriately detect -1st-order light L1, the photodetector 2 has an insulating film 23 and a silicon nitride film 24 arranged on the light-receiving surface 21a of the first photodetector 21, as shown in Figure 4. Note that the insulating film 23 and silicon nitride film 24 are not shown in Figures 1 and 3. [Configuration of the first photodetector] 【0042】-The configuration of the first photodetector 21 when the primary light L1 is ultraviolet light (for example, light in the wavelength range of 190 nm to 440 nm) will be described. As shown in Figure 4, the first photodetector region 211 includes a plurality of first pixels 211a arranged in a row in the X-axis direction. The second photodetector region 212 includes a plurality of second pixels 212a arranged in a row in the X-axis direction. The third photodetector region 213 includes a plurality of third pixels 213a arranged in a row in the X-axis direction. The plurality of first pixels 211a, the plurality of second pixels 212a, and the plurality of third pixels 213a are a plurality of pixels each having the same structure, and are a plurality of pixels arranged one-dimensionally in the X-axis direction with equal pitch. 【0043】 As shown in Figures 4, 5, and 6, an insulating film 23 is arranged on the light-receiving surface 21a of the first photodetector 21. The insulating film 23 integrally covers the first photodetector region 211, the second photodetector region 212, and the third photodetector region 213. The insulating film 23 is a BPSG (Boro-phosphosilite glass) film, a PSG (Phosphosilite glass) film, or an SOG (spin-on-glass) film integrally formed on the light-receiving surface 21a. The transmittance of ultraviolet light to the insulating film 23 is, for example, 80% or more and less than 100%. As an example, the BPSG film and the PSG film are formed by the CVD method (e.g., atmospheric pressure CVD, reduced pressure CVD, plasma CVD, etc.). As an example, the SOG film is formed by, for example, heat-treating liquid SOG applied by spin coating. 【0044】Multiple irregularities are formed on the surface 23a of the insulating film 23 opposite to the light-receiving surface 21a. The surface 23b of the insulating film 23 on the light-receiving surface 21a side extends along the light-receiving surface 21a. The multiple irregularities on the surface 23a of the insulating film 23 may be formed by arranging multiple recesses in a two-dimensional manner, or by arranging multiple protrusions in a two-dimensional manner. In either case, the multiple irregularities are formed so that the curvature of the surface 23a changes continuously (for example, so that it changes sinusoidally in a cross section parallel to the Z-axis direction). The thickness of the insulating film 23 at the bottom of the multiple irregularities is, for example, 0.5 μm or more and 1.5 μm or less. The width of the multiple irregularities in the thickness direction of the insulating film 23 (i.e., the height difference between the bottom and top of the multiple irregularities) is, for example, 0.4 μm or more and 1.2 μm or less. The distance between the centers of adjacent bottoms or adjacent tops in the multiple irregularities is, for example, 1 μm or more and 5 μm or less. 【0045】 As shown in Figures 4 and 6, a silicon nitride film 24 is arranged on the surface 23a of the insulating film 23. In other words, the silicon nitride film 24 is arranged on the light-receiving surface 21a of the first photodetector 21 via the insulating film 23. To put it another way, the insulating film 23 is arranged between the light-receiving surface 21a of the first photodetector 21 and the silicon nitride film 24. The silicon nitride film 24 is formed along the surface 23a of the insulating film 23. The surface 24a of the silicon nitride film 24 opposite to the light-receiving surface 21a, and the surface 24b of the silicon nitride film 24 on the light-receiving surface 21a side, extend along the surface 23a of the insulating film 23. In other words, each surface 24a, 24b of the silicon nitride film 24 has multiple irregularities formed to correspond to the multiple irregularities formed on the surface 23a of the insulating film 23. The thickness of the silicon nitride film 24 (average distance between surface 24a and surface 24b in the Z-axis direction) is smaller than the thickness of the insulating film 23 at the bottom of the multiple irregularities. In the spectrometer 1, the thickness of the silicon nitride film 24 is between 190 nm and 400 nm. As an example, the silicon nitride film 24 is formed by thermal nitriding, sputtering, or CVD. 【0046】As shown in Figure 4, the coverage rate of the silicon nitride film 24 in the first photodetection region 211 (the percentage of the first photodetection region 211 covered by the silicon nitride film 24 when viewed from a direction perpendicular to the light-receiving surface 21a) is 0%. The coverage rate of the silicon nitride film 24 in the second photodetection region 212 (the percentage of the second photodetection region 212 covered by the silicon nitride film 24 when viewed from a direction perpendicular to the light-receiving surface 21a) is 50%. In other words, the coverage rate of the silicon nitride film 24 in the second photodetection region 212 is between 25% and 75%. The coverage rate of the silicon nitride film 24 in the third photodetection region 213 (the percentage of the third photodetection region 213 covered by the silicon nitride film 24 when viewed from a direction perpendicular to the light-receiving surface 21a) is 100%. Thus, the spectrometer 1 satisfies the condition that "the coverage rate of the silicon nitride film 24 in the third photodetection region 213 is greater than the coverage rate of the silicon nitride film 24 in the first photodetection region 211, and the coverage rate of the silicon nitride film 24 in the second photodetection region 212 is greater than or equal to the coverage rate of the silicon nitride film 24 in the first photodetection region 211, and less than or equal to the coverage rate of the silicon nitride film 24 in the third photodetection region 213." 【0047】 The coverage of the silicon nitride film 24 in the second photodetection region 212 increases as it approaches the third photodetection region 213. In other words, the coverage of the silicon nitride film 24 in the second photodetection region 212 decreases as it moves away from the first photodetection region 211. In the spectrometer 1, the coverage of the silicon nitride film 24 in the second photodetection region 212 changes linearly, becoming approximately 0% at the second pixel 212a closest to the first photodetection region 211 and approximately 100% at the second pixel 212a closest to the third photodetection region 213. [Characteristics of the silicon nitride film] 【0048】Figure 7(a) is a graph showing the transmittance characteristics of the "350 nm thick silicon nitride film 24". As shown in Figure 7(a), the transmittance of "light in the wavelength range of 240 nm or less" for the "350 nm thick silicon nitride film 24" is lower than 10%, and the transmittance of "light in the wavelength range of 390 nm or more" for the "350 nm thick silicon nitride film 24" is higher than 80%. Furthermore, the transmittance of "light in the wavelength range of 190 nm to 440 nm" for the "350 nm thick silicon nitride film 24" increases gradually as the wavelength increases. 【0049】 When the -1st-order light L1 is ultraviolet light (for example, light in the wavelength range of 190 nm to 440 nm), the amount of light in the wavelength range of 200 nm or less tends to decrease due to the characteristics of the light source. Therefore, the characteristic of the silicon nitride film 24, in which the transmittance increases gradually as the wavelength increases, is extremely effective in suppressing the saturation of the charge generated in response to the incidence of the -1st-order light L1 in each second pixel 212a of the second photodetection region 212 and each third pixel 213a of the third photodetection region 213. 【0050】 Figure 7(b) is a graph showing the sensitivity characteristics for the first photodetector region 211 and the third photodetector region 213. As shown in Figure 7(b), in the first photodetector region 211, where the coverage rate of the silicon nitride film 24 is 0%, sufficient sensitivity is obtained for "light in the wavelength range of 240 nm or less". In the first photodetector region 211, the transmittance increases as the wavelength increases, but this is not a problem because light on the longer wavelength side does not enter the first photodetector region 211. Furthermore, in the third photodetector region 213, where the coverage rate of the "silicon nitride film 24 with a thickness of 350 nm" is 100%, the sensitivity for "light in the wavelength range of 240 nm or less" is low, while high sensitivity is obtained for "light in the wavelength range of 390 nm or more". The fact that the sensitivity for "light in the wavelength range of 240 nm or less" is low in the third photodetector region 213 is effective because it can suppress the detection of higher-order diffracted light on the shorter wavelength side. 【0051】Figure 8(a) is a graph showing the transmittance characteristics for "silicon nitride film 24 with a thickness of 190 nm" and "silicon nitride film 24 with a thickness of 250 nm". Figure 8(b) is a graph showing the transmittance characteristics for "silicon nitride film 24 with a thickness of 250 nm" and "silicon nitride film 24 with a thickness of 400 nm". 【0052】 As shown in Figure 8(a), the transmittance of light with a wavelength range of 240 nm or less for the silicon nitride film 24 with a thickness of 190 nm is lower than 10%, and the transmittance of light with a wavelength range of 390 nm or more for the silicon nitride film 24 with a thickness of 190 nm is higher than 75%. As shown in Figures 8(a) and (b), the transmittance of light with a wavelength range of 240 nm or less for the silicon nitride film 24 with a thickness of 250 nm is lower than 5%, and the transmittance of light with a wavelength range of 390 nm or more for the silicon nitride film 24 with a thickness of 250 nm is higher than 70%. As shown in Figure 8(b), the transmittance of light with a wavelength range of 240 nm or less for the silicon nitride film 24 with a thickness of 400 nm is lower than 3%, and the transmittance of light with a wavelength range of 390 nm or more for the silicon nitride film 24 with a thickness of 400 nm is higher than 55%. 【0053】 Based on the above, when the -1st-order light L1 is ultraviolet light (for example, light in the wavelength range of 190 nm to 440 nm), the thickness of the silicon nitride film 24 is preferably 190 nm to 400 nm, and more preferably 230 nm to 270 nm. [Coverage of silicon nitride film in the second photodetection region] 【0054】Figure 9 is a graph showing the characteristics of stray light emission and sensitivity for the comparative example, and for Example 1. Figure 10 is a graph showing the characteristics of stray light emission and sensitivity for Example 2, and for Example 3. In each graph, the horizontal axis "wavelength [nm]" corresponds to the pixel (first pixel 211a, second pixel 212a, or third pixel 213a) to which the -1st order light of that wavelength is incident. The graph showing the characteristics of stray light emission is the result when light of multiple wavelengths is incident on the spectrometer 1 as emission lines (i.e., for each wavelength). In each graph showing the characteristics of emission line stray light, the wavelength indicated by the solid line is 200 nm, the wavelength indicated by the dashed line is 240 nm, the wavelength indicated by the dashed line is 280 nm, the wavelength indicated by the thin solid line is 320 nm, the wavelength indicated by the double dashed line is 360 nm, the wavelength indicated by the thin dashed line is 400 nm, and the wavelength indicated by the dotted line is 440 nm. 【0055】 A comparative example is the case where the coverage rate of the silicon nitride film 24 in the first photodetection region 211, the second photodetection region 212, and the third photodetection region 213 is 0% (i.e., the silicon nitride film 24 is not placed on the light-receiving surface 21a of the first photodetection unit 21). As shown in Figure 9, in the comparative example, the pixel that should detect the -1st order light with a wavelength of 380 nm detects the -2nd order light with a wavelength of 190 nm. 【0056】 In Example 1, the coverage rates of the silicon nitride film 24 in the first photodetection region 211, the second photodetection region 212, and the third photodetection region 213 are 0%, 50%, and 100%, respectively, and the second photodetection region 212 is defined as "pixels 114 to 136 out of all pixels from 1 to 288". As shown in Figure 9, in Example 1, the detection of -2nd order light at a wavelength of 190 nm is suppressed in pixels that should detect -1st order light at a wavelength of 380 nm, but the decrease in sensitivity in pixels that should detect -1st order light at wavelengths of 310 to 330 nm is rapid. 【0057】In Example 2, the coverage rates of the silicon nitride film 24 in the first photodetection region 211, the second photodetection region 212, and the third photodetection region 213 are 0%, 50%, and 100%, respectively, and the second photodetection region 212 is defined as "pixels 114 to 180 out of all pixels 1 to 288". As shown in Figure 10, in Example 2, the decrease in sensitivity seen in Example 1 is suppressed, but a small amount of -2nd order light at a wavelength of 190 nm is detected in pixels that should detect -1st order light at a wavelength of 380 nm. 【0058】 In Example 3, the coverage rates of the silicon nitride film 24 in the first photodetection region 211, the second photodetection region 212, and the third photodetection region 213 are 0%, 50%, and 100%, respectively, and the second photodetection region 212 is defined as "pixels 110 to 150 out of all pixels from 1 to 288". As shown in Figure 10, in Example 3, detection of -2nd order light at a wavelength of 190 nm in pixels that should detect -1st order light at a wavelength of 380 nm, as well as the decrease in sensitivity seen in Example 1, are suppressed. 【0059】 From the above results, it can be seen that in order to more appropriately detect the -1st-order light L1 when it is ultraviolet light (for example, light in the wavelength range of 190 nm to 440 nm), it is important to determine how the second photodetection region 212 should be set in the first photodetection unit 21. 【0060】 Here, an example of setting the second photodetection region 212 will be described. As a premise, the detection target is -1st order light in the wavelength range of 190 nm to 440 nm, and in the first photodetection unit 21 with 256 pixels, the first pixel detects -1st order light with a wavelength of 160 nm, and the 256th pixel detects -1st order light with a wavelength of 480 nm. 【0061】Based on this premise, the second photodetection region 212 is set such that the transmittance to the silicon nitride film 24 is between 5% and 80%. When the thickness of the silicon nitride film 24 is 250 nm, as shown in Figure 11, the transmittance to the silicon nitride film 24 is 5% for light with a wavelength of about 250 nm, and the transmittance to the silicon nitride film 24 is 80% for light with a wavelength of about 400 nm. Therefore, the second photodetection region 212 is constructed by a plurality of pixels that detect -1st order light in the wavelength range of 250 to 400 nm. In other words, in the plurality of pixels that detect -1st order light in the wavelength range of 250 to 400 nm, the coverage of the silicon nitride film 24 is changed linearly so that it is approximately 0% at the shortest wavelength pixel and approximately 100% at the longest wavelength pixel. 【0062】 Furthermore, it is more preferable to set the second photodetection region 212 such that the transmittance to the silicon nitride film 24 is 20% or more and 70% or less, that is, to configure the second photodetection region 212 with a plurality of pixels that detect -1st order light in the wavelength range of 280 to 380 nm, as shown in Figure 11. It is even more preferable to set the second photodetection region 212 such that the transmittance to the silicon nitride film 24 is 25% or more and 60% or less, that is, to configure the second photodetection region 212 with a plurality of pixels that detect -1st order light in the wavelength range of 300 to 350 nm, as shown in Figure 11. 【0063】 When the second photodetection region 212 is formed by pixels a to b, if the width of the pixels in the X-axis direction is d and the width of the pixels in the Y-axis direction is h, then the slope α [radian] (see Figure 4) of the coverage of the silicon nitride film 24 that changes linearly in pixels a to b is given by "α = tan －１ (h / ((b-a+1)×d))) [Function and effect] 【0064】In the optical splitter 1, a silicon nitride film 24 having a characteristic of changing transmittance in the wavelength range of ultraviolet light is disposed on the light receiving surface 21a of the first light detection unit 21. Thus, in the photodetector 2, the silicon nitride film 24 can function as a filter for ultraviolet light, so that the overall size can be reduced. Also, the coverage rate of the silicon nitride film 24 in the third light detection region 213 where light L1 in the third wavelength range longer than the first wavelength range and the second wavelength range is incident is Ｌ greater than the coverage rate of the silicon nitride film 24 in the first light detection region 211 where light L1 in the first wavelength range is incident (in the optical splitter 1, light L1 in the third wavelength range longer than the first wavelength range and the second wavelength range is Ｓ incident on the third light detection region 213 covered by the silicon nitride film 24, and the first light detection region 211 where light L1 in the first wavelength range is incident is not covered by the silicon nitride film 24). Thus, when the -1st order light L1 is ultraviolet light, higher-order diffracted light of light L1 in the first wavelength range and higher-order diffracted light of light in the wavelength range shorter than the first wavelength range can be cut by the silicon nitride film 24, so that the incidence of such higher-order diffracted light on the third light detection region 213 can be suppressed. Further, the coverage rate of the silicon nitride film 24 in the second light detection region 212 where light L1 in the second wavelength range longer than the first wavelength range is incident is Ｌ equal to or greater than the coverage rate of the silicon nitride film 24 in the first light detection region 211 where light L1 in the first wavelength range is incident, and is equal to or less than the coverage rate of the silicon nitride film 24 in the third light detection region 213 where light L1 in the third wavelength range longer than the second wavelength range is incident. Thus, when the -1st order light L1 is ultraviolet light, a sharp decrease in sensitivity within the second light detection region 212 can be suppressed. As described above, according to the optical splitter 1, while reducing the overall size, when the -1st order light L1 is ultraviolet light, the -1st order light L1 can be appropriately detected. 【0065】 ​​​​​​​​​​In spectrometer 1, the thickness of the silicon nitride film 24 is between 190 nm and 400 nm. This allows for more appropriate detection of ultraviolet light, specifically the -1st order light L1. 【0066】 In the spectrometer 1, the second wavelength range of the -1st order light L1 detected in the second photodetection region 212 is included in the wavelength range of light in which the transmittance to the silicon nitride film 24 is between 5% and 80%, and the coverage rate of the silicon nitride film 24 in the second photodetection region 212 increases as it approaches the third photodetection region 213. This makes it possible to reliably suppress the sharp decrease in sensitivity within the second photodetection region 212 when the -1st order light L1 is ultraviolet light. 【0067】 In the spectrometer 1, an insulating film 23 is placed between the light-receiving surface 21a and the silicon nitride film 24 in the photodetector 2. Multiple irregularities are formed on the surface 23a of the insulating film 23, and the silicon nitride film 24 is formed along the surface 23a of the insulating film 23. As a result, when the -1st order light L1 is incident on the light-receiving surface 21a of the first photodetector 21, multiple interferences with different optical path lengths occur within the insulating film 23. This causes the periods of variation in spectral sensitivity with respect to the wavelength of the -1st order light L1 to cancel each other out, thereby reducing sensitivity variation in the wavelength range of the -1st order light L1. 【0068】 In the spectrometer 1, the insulating film 23 is a BPSG film, a PSG film, or an SOG film. This allows for the easy and reliable formation of an insulating film 23 having a surface 23a with multiple irregularities. 【0069】 In the spectrometer 1, the coverage of the silicon nitride film 24 in the first photodetection region 211 is 0%, the coverage of the silicon nitride film 24 in the second photodetection region 212 is 25% to 75%, and the coverage of the silicon nitride film 24 in the third photodetection region 213 is 100%. This allows for more appropriate detection of ultraviolet light, which is the -1st order light L1. [Modified example] 【0070】This disclosure is not limited to the examples described above. For example, as shown in Figure 12, in the first photodetector 21, the silicon nitride film 24 may be placed on the light-receiving surface 21a, and the insulating film 23 may be placed on the surface 24a of the silicon nitride film 24. In other words, the silicon nitride film 24 may be placed between the light-receiving surface 21a and the insulating film 23. In the first photodetector 21 shown in Figure 12, each surface 24a, 24b of the silicon nitride film 24 extends along the light-receiving surface 21a. The surface 23b of the insulating film extends along the surface 24a of the silicon nitride film 24, and a plurality of irregularities are formed on the surface 23a of the insulating film 23. In that case as well, when the -1st order light L1 is incident on the light-receiving surface 21a of the first light detection unit 21, multiple interferences with different optical path lengths occur within the insulating film 23, causing the periods of variation in spectral sensitivity with respect to the wavelength of the -1st order light L1 to cancel each other out, thereby reducing sensitivity variation in the wavelength range of the -1st order light L1. 【0071】 However, comparing the configuration of the first photodetector 21 shown in Figure 6 with the configuration of the first photodetector 21 shown in Figure 12, the configuration of the first photodetector 21 shown in Figure 6 is advantageous over the configuration of the first photodetector 21 shown in Figure 12 in that the transmittance of ultraviolet light to the silicon nitride film 24 tends to increase more gradually as the wavelength increases. It is presumed that this difference occurs because, in the configuration of the first photodetector 21 shown in Figure 6, the silicon nitride film 24 extends along a plurality of irregularities formed on the surface 23a of the insulating film 23, whereas, in the configuration of the first photodetector 21 shown in Figure 12, the transmittance of the flat silicon nitride film 24 is directly affected by the effect of the plurality of irregularities formed on the surface 23a of the insulating film 23. 【0072】From this, the following invention is established: "A spectrometer comprising: a spectrometer that spectrally analyzes and reflects measurement light; and a photodetector having a photodetector that detects diffracted light of a predetermined order spectrally analyzed from the measurement light reflected by the spectrometer, wherein the photodetector further comprises: an insulating film disposed on the light-receiving surface of the photodetector; and a silicon nitride film disposed on the insulating film, wherein a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface; and the silicon nitride film is formed along the surface of the insulating film." 【0073】 In the first photodetection unit 21, the coverage of the silicon nitride film 24 only needs to satisfy the following conditions: "The coverage of the silicon nitride film 24 in the third photodetection region 213 is greater than the coverage of the silicon nitride film 24 in the first photodetection region 211, and the coverage of the silicon nitride film 24 in the second photodetection region 212 is greater than or equal to the coverage of the silicon nitride film 24 in the first photodetection region 211 and less than or equal to the coverage of the silicon nitride film 24 in the third photodetection region 213." Therefore, the coverage of the silicon nitride film 24 in the first photodetection region 211 may be higher than 0%. The coverage of the silicon nitride film 24 in the third photodetection region 213 may be lower than 100%. The coverage of the silicon nitride film 24 in the second photodetection region 212 may be the same as the coverage of the silicon nitride film 24 in the first photodetection region 211. The coverage rate of the silicon nitride film 24 in the second photodetection region 212 may be the same as the coverage rate of the silicon nitride film 24 in the third photodetection region 213. 【0074】 When the coverage of the silicon nitride film 24 in the second photodetection region 212 increases as it approaches the third photodetection region 213, it may increase not only linearly, but also in a curved shape that is convex outward, or in a curved shape that is convex inward, or in a stepwise manner for at least one second pixel 212a. 【0075】In the first light detection unit 21, the multiple first pixels 211a may be arranged in a two-dimensional manner. In this case, for each set of multiple first pixels 211a arranged in the Y-axis direction, the signals output from the multiple first pixels 211a arranged in the Y-axis direction may be added together by binning. This addition by binning may be performed by an external processing unit or by a circuit unit of the light detection element 2. The first light detection region 211 may contain at least one first pixel 211a. The second light detection region 212 may contain at least one second pixel 212a. The third light detection region 213 may contain at least one third pixel 213a. 【0076】 In the spectrometer 1, the first photodetector 21 only needs to detect diffracted light of a predetermined order that has been spectrally separated by the spectrometer 3 from the measurement light L reflected by the spectrometer 3. For example, the first photodetector 21 may detect the +1st order light that has been spectrally separated by the spectrometer 3 from the measurement light L reflected by the spectrometer 3. 【0077】 1...Spectrometer, 2...Photodetector, 3...Spectroscopic unit, 21...First photodetector (photodetector), 21a...Light-receiving surface, 23...Insulating film, 23a...Surface, 24...Silicon nitride film, 211...First photodetector region, 211a...First pixel, 212...Second photodetector region, 212a...Second pixel, 213...Third photodetector region, 213a...Third pixel, L...Measurement light, L1...-1st order light (diffracted light of a predetermined order), L1 Ｓ ...light in the first wavelength range, L1 Ｍ ...light in the second wavelength range, L1 Ｌ ...light in the third wavelength range.

Claims

1. The device comprises: a spectrometer that spectrally analyzes and reflects measurement light; a photodetector that detects diffracted light of a predetermined order spectrally analyzed by the spectrometer from the measurement light reflected by the spectrometer; and a photodetector having a silicon nitride film disposed on the light-receiving surface of the photodetector, wherein the photodetector has: a first photodetector region including at least one first pixel; a second photodetector region including at least one second pixel; and a third photodetector region including at least one third pixel, wherein when viewed from a first direction in which the measurement light is incident on the spectrometer, the second photodetector region is positioned between the first photodetector region and the third photodetector region in a second direction intersecting the first direction, and the spectrometer causes light in a first wavelength range of the diffracted light to be incident on the first photodetector region, light in a second wavelength range with a longer wavelength than the first wavelength range of the diffracted light to be incident on the second photodetector region, and light in a third wavelength range with a longer wavelength than the second wavelength range of the diffracted light to be incident on the third photodetector region. A spectrometer in which the coverage rate of the silicon nitride film in the third photodetection region is greater than the coverage rate of the silicon nitride film in the first photodetection region, and the coverage rate of the silicon nitride film in the second photodetection region is greater than or equal to the coverage rate of the silicon nitride film in the first photodetection region and less than or equal to the coverage rate of the silicon nitride film in the third photodetection region.

2. The spectrometer according to claim 1, wherein the thickness of the silicon nitride film is 190 nm or more and 400 nm or less.

3. The spectrometer according to claim 1 or 2, wherein the second photodetection region includes a plurality of second pixels arranged in the second direction, the second wavelength range is included in the wavelength range of light in which the transmittance to the silicon nitride film is 5% or more and 80% or less, and the coverage of the silicon nitride film in the second photodetection region increases as it approaches the third photodetection region.

4. The spectrometer according to any one of claims 1 to 3, wherein the photodetector further comprises an insulating film disposed between the light-receiving surface and the silicon nitride film, a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface, and the silicon nitride film is formed along the surface of the insulating film.

5. The spectrometer according to any one of claims 1 to 3, wherein the photodetector further comprises an insulating film disposed on the light-receiving surface, the silicon nitride film is disposed between the light-receiving surface and the insulating film, and a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface.

6. The spectrometer according to claim 4 or 5, wherein the insulating film is a BPSG film, a PSG film, or an SOG film.

7. The spectrometer according to any one of claims 1 to 6, wherein the coverage of the silicon nitride film in the first photodetection region is 0%, the coverage of the silicon nitride film in the second photodetection region is 25% or more and 75% or less, and the coverage of the silicon nitride film in the third photodetection region is 100%.

8. The device comprises: a spectrometer that spectrally analyzes and reflects measurement light; a photodetector that detects diffracted light of a predetermined order spectrally analyzed by the spectrometer from the measurement light reflected by the spectrometer; and a photodetector having a silicon nitride film disposed on the light-receiving surface of the photodetector, wherein the photodetector has: a first photodetector region including at least one first pixel; a second photodetector region including at least one second pixel; and a third photodetector region including at least one third pixel, wherein when viewed from a first direction in which the measurement light is incident on the spectrometer, the second photodetector region is positioned between the first photodetector region and the third photodetector region in a second direction intersecting the first direction; the spectrometer causes light in a first wavelength range of the diffracted light to be incident on the first photodetector region; light in a second wavelength range with a longer wavelength than the first wavelength range of the diffracted light to be incident on the second photodetector region; and light in a third wavelength range with a longer wavelength than the second wavelength range of the diffracted light to be incident on the third photodetector region. A spectrometer in which the silicon nitride film does not cover the first photodetection region but covers the third photodetection region.

9. The spectrometer according to claim 8, wherein the thickness of the silicon nitride film is 190 nm or more and 400 nm or less.

10. The spectrometer according to claim 8 or 9, wherein the second photodetection region includes a plurality of second pixels arranged in the second direction, the second wavelength range is included in the wavelength range of light in which the transmittance to the silicon nitride film is 5% or more and 80% or less, and the coverage of the silicon nitride film in the second photodetection region increases as it approaches the third photodetection region.

11. The spectrometer according to any one of claims 8 to 10, wherein the photodetector further comprises an insulating film disposed between the light-receiving surface and the silicon nitride film, a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface, and the silicon nitride film is formed along the surface of the insulating film.

12. The spectrometer according to any one of claims 8 to 10, wherein the photodetector further comprises an insulating film disposed on the light-receiving surface, the silicon nitride film is disposed between the light-receiving surface and the insulating film, and a plurality of irregularities are formed on the surface of the insulating film opposite to the light-receiving surface.

13. The spectrometer according to claim 11 or 12, wherein the insulating film is a BPSG film, a PSG film, or an SOG film.

14. The spectrometer according to any one of claims 8 to 13, wherein the coverage rate of the silicon nitride film in the first photodetection region is 0%, the coverage rate of the silicon nitride film in the second photodetection region is 25% or more and 75% or less, and the coverage rate of the silicon nitride film in the third photodetection region is 100%.

Images