Image sensor and method of manufacturing an image sensor

Abstract

An image sensor (10) comprises a pixel array (100) including a plurality of pixels (101) and a first spectral filter set comprising a set of first spectral filters (131). First positions of the pixel array (100) are assigned to a first pattern for the first spectral filter set. The image sensor (10) further comprises a second spectral filter set comprising a set of second spectral filters (132). The first spectral filters (131) are different from the second spectral filters (132) and the second spectral filters (132) are arranged at positions other than the first positions. First pixels (102) correspond to pixels comprising a first spectral filter (131) and second pixels (103) correspond to pixels comprising a second spectral filter (132). A number of the first pixels (102) is larger than the number of the second pixels (103).

Description

[0001] 2024PF00871 1

[0002] IMAGE SENSOR AND METHOD OF MANUFACTURING AN IMAGE SENSOR

[0003] Color sensors are commonly used in cameras in order to measure the light-correlated color temperature ( CCT ) and for providing precise color information about the surrounding environment . Generally, ef forts are taken to improve color sensors and cameras including color sensors .

[0004] It is an obj ect of the present invention to provide an improved image sensor and an improved method of manufacturing an image sensor .

[0005] SUMMARY

[0006] According to embodiments , the above obj ects are achieved by the claimed matter according to the independent claims . Further developments are defined in the dependent claims .

[0007] According to embodiments , an image sensor comprises a pixel array including a plurality of pixels and a first spectral filter set comprising a set of first spectral filters . First positions of the pixel array are assigned to a first pattern for the first spectral filter set . The image sensor further comprises a second spectral filter set comprising a set of second spectral filters . The first spectral filters are di fferent from the second spectral filters and the second spectral filters are arranged at some of the first positions . First pixels correspond to pixels comprising a first spectral filter and second pixels correspond to pixels comprising a second spectral filter . A number of the first pixels is larger than the number of the second pixels . 2024PF00871 2

[0008] For example , the feature that the first spectral filters are di f ferent from the second spectral filters may mean that a wavelength range transmitted by any of the first spectral filters may be di f ferent from the wavelength range transmitted by any of the second spectral filters . This feature is intended to mean that that the wavelength range transmitted by one of the first spectral filters may overlap partially with the wavelength range transmitted by one of the second spectral filters or may comprise the wavelength range transmitted by one of the second spectral filters . However, the wavelength range transmitted by the f irst spectral filter exceeds either at a lower or an upper boundary by at least 50 nm the wavelength range transmitted by the second spectral filter .

[0009] According to embodiments , exclusively first spectral filters may be arranged directly adj acent to each of the second spectral filters .

[0010] According to further embodiments , a plurality of second spectral filters may be grouped to form a subarray .

[0011] For example , the plurality of second spectral filters include di f ferent spectral filters , so that each of the second spectral filters is directly adj acent exclusively to di f ferent second spectral filters .

[0012] According to further embodiments , the plurality of second spectral filters may include second spectral filters being transmissive for di f ferent wavelength ranges , wherein the second spectral filters for identical wavelength ranges are grouped . In this context , the term identical wavelength ranges is intended to mean that an upper or lower boundary of the wavelength ranges di f fers by less than 50 nm . 2024PF00871 3

[0013] The image sensor may further comprise a di f fuser arranged on a side of the second spectral filters remote from a detection portion of the associated pixel .

[0014] For example , the positions of the second spectral filters may be arranged at a regular second pattern . According to further examples , positions of the second spectral filters are arranged at an irregular second pattern . Moreover, within a pixel array, some positions may be arranged at a regular second pattern and other positions may be arranged at an irregular second pattern .

[0015] The image sensor may further comprise a readout circuit that is configured to read out pixel signals from the pixels . The image sensor may be operable in an image capturing mode and an ambient light sensing mode .

[0016] For example , in the ambient light sensing mode only second pixels are addressed . Further the readout circuit may be configured to read out pixel signals from exclusively the second pixels .

[0017] The image sensor may further comprise a control unit configured to determine a color temperature at di f ferent positions of the pixel array based on readout values read out during the ambient light sensing mode .

[0018] For example , the control unit may be further configured to determine white balance values for the di f ferent positions of the pixel array .

[0019] According to further embodiments , the image sensor additionally comprise a clear filter, the clear filter being transmissive for a wavelength range to be detected by photosensitive 2024PF00871 4 elements of the pixels . For example , the clear filter may be arranged at at least one of the first positions , thereby defining a flicker detection pixel .

[0020] According to embodiments , the image sensor may further comprise a flicker readout circuit and the image sensor may be further configured to be operated in a flicker readout mode . In the flicker readout mode the flicker readout circuit is configured to readout pixel signals from exclusively the flicker detection pixels .

[0021] For example , a number of spectral filters of the first spectral filter set may be smaller than the number of spectral filters of the second spectral filter set .

[0022] A method of manufacturing an image sensor comprises providing an array of photosensitive elements over a CMOS substrate , arranging first spectral filters of a first spectral filter set at first positions of the array of photosensitive elements in accordance with a first pattern for the first spectral filters , thereby defining first pixels . The method further comprises arranging second spectral filters of a second spectral filter set over the photosensitive elements thereby defining second pixels . A number of the first pixels is larger than the number of the second pixels .

[0023] For example , the second spectral filters may be formed over a carrier substrate , and arranging the second spectral filters comprises trans ferring the second spectral filters to the array of photosensitive elements .

[0024] According to embodiments , the second spectral filters may be trans ferred using a mass trans fer process . 2024PF00871 5

[0025] According to further embodiments , an image sensor comprises a pixel array including a plurality of pixels , a first spectral filter set comprising a set of first spectral filters , first positions of the pixel array being assigned to a first pattern for the first spectral filters . The image sensor further comprises a clear filter, the clear filter being transmissive for a wavelength range to be detected by photosensitive elements of the pixels , wherein the clear filter is arranged at at least one of the first pos itions to define flicker detection pixels , wherein first pixel s correspond to pixels comprising a first spectral filter .

[0026] According to embodiments , the image sensor may further comprise a flicker readout circuit and the image sensor may be further configured to be operated in a flicker readout mode . In the flicker readout mode the flicker readout circuit is configured to readout pixel signals from exclusively the flicker detection pixels .

[0027] The image sensor may further comprise a control unit configured to synchroni ze an image capturing process performed by the first pixels with a fl icker rate of a light source when a flickering has been detected .

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this speci fication . The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principles . Other embodiments of the invention and many of the intended advantages will be readily appreciated, as they become better understood by reference to the following detailed description . The elements of 2024PF00871 6 the drawings are not necessarily to scale relative to each other.

[0030] Like reference numbers designate corresponding similar parts.

[0031] Fig. 1A shows a top view of an image sensor according to embodiments .

[0032] Fig. IB shows a top view of an image sensor according to further embodiments.

[0033] Figs. 1C and ID show top views of image sensors according to further embodiments.

[0034] Fig. 2 is a schematic view of components of an image sensor according to embodiments.

[0035] Fig. 3 shows a vertical cross-sectional view of a portion of an image sensor according to embodiments.

[0036] Figs. 4A to 4C show cross-sectional views of a workpiece when forming an image sensor according to embodiments.

[0037] Fig. 4D summarizes a method according to embodiments.

[0038] DETAILED DESCRIPTION

[0039] In the following detailed description reference is made to the accompanying drawings, which form a part hereof and in which are illustrated by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology such as "top", "bottom", "front", "back", "over", "on", "above", "leading", "trailing" etc. is used with reference to the orientation of the Figures being described. Since components of embodiments of the invention can be positioned in a number of different orientations, the directional terminology is used for 2024PF00871 7 purposes of illustration and is in no way limiting . It is to be understood that other embodiments may be utili zed and structural or logical changes may be made without departing from the scope defined by the claims .

[0040] The description of the embodiments is not limiting . In particular, elements of the embodiments described hereinafter may be combined with elements of di f ferent embodiments .

[0041] The terms " lateral" and "hori zontal" as used in this speci fication intends to describe an orientation parallel to a first surface of a substrate or semiconductor body . This can be for instance the surface of a wafer or a die .

[0042] The term "vertical" as used in this speci fication intends to describe an orientation which is arranged perpendicular to the first surface of a substrate or semiconductor body .

[0043] Fig . 1A shows a top view of an image sensor 10 according to embodiments . The image sensor 10 comprises a pixel array 100 including a plurality of pixels 101 . Moreover, the image sensor comprises a first spectral filter set comprising a set of first spectral filters 131 . First positions of the pixel array 100 are assigned to a first pattern for the first spectral filters 131 . The image sensor 10 further comprises a second spectral filter set comprising a set of second spectral filters 132 . The first spectral filters 131 are di f ferent from the second spectral filters 132 , and the second spectral filters 132 are arranged at some of the first positions .

[0044] First pixels 102 correspond to pixels comprising a first spectral filter 131 and second pixels 103 correspond to pixels comprising a second spectral filter 132 . A number of the first pixels 102 larger than the number of the second pixels 103 . 2024PF00871 8

[0045] Each of the pixels 101 may comprise a photosensitive element (not illustrated in Fig. 1A, illustrated in Fig. 2A) and, optionally, a spectral filter 108 arranged over the photosensitive element. In more detail, incident light enters the photosensitive element after being transmitted by the spectral filter.

[0046] The pixels 101 may be arranged at a regular pattern, e.g. in rows and columns. According to further embodiments, the pixels 101 may as well be arranged at different patterns. For example, the first spectral filter set may comprise spectral filters of a certain color system, e.g. the R (red) , B (blue) and G (green) color system. Usually, the single spectral filters are arranged at certain patterns, e.g. a Bayer pattern. As is to be clearly understood, any other suitable color system, e.g. comprising more colors may be employed. Moreover, the spectral filters may be arranged in any other suitable pattern.

[0047] For example, the first spectral filters 131 may be implemented as so-called broad band filters having a comparatively large wavelength range that is transmitted by the first spectral filters. For example, the first spectral filters 131 may be implemented as absorption filters which absorb wavelength ranges outside the transmitted wavelength range. The first spectral filters 131 may comprise dyes, e.g. organic dyes. For example, transmitted wavelength ranges may comprise visible wavelength ranges .

[0048] The second spectral filters 132 may be so-called multi-spectral filters. In more detail, according to embodiments, the second spectral filters 132 may only transmit a small wavelength range. For example, the second spectral filters 132 may be implemented as interference filters, i.e. the second spectral filters may comprise layer stacks which - due to interference - only trans- 2024PF00871 9 mit predetermined wavelength ranges. Electromagnetic radiation having wavelengths outside the predetermined wavelength ranges may be reflected. For example, wavelength ranges transmitted by the second spectral filter may comprise visible wavelength ranges. Further wavelength ranges transmitted by the second spectral filter may be outside the visible wavelength range, e.g. the IR or UV range.

[0049] Generally, the number of second pixels 103 may be less than the number of first pixels 102. For example, the number of first pixels 102 may be at least 80 % of the total number of pixels 101. Moreover, the first set may comprise a number of spectral filters which is smaller than the number of spectral filters of the second set. For example, the first set may comprise three types of spectral filters, R, G and B. Moreover, the second set of spectral filters may comprise a larger number, e.g. more than 8, e.g. 16 or even more.

[0050] The right-hand portion of Fig. 1A shows an enlarged portion of a region of a pixel array illustrating examples of arrangements of first spectral filters 131 and second spectral filters 132 and, consequently, of first pixels 102 or second pixels 103

[0051] As is illustrated on the right-hand side of Fig. 1A, according to (i) , a subarray 107 of second pixels 103 may be embedded in the array of first pixels 102. In more detail, the second spectral filters 132 are arranged at first positions that otherwise would have been occupied by first spectral filters 131. For example, the second spectral filters 132 may be arranged so that a subarray 107 is formed, i.e. the second spectral filters 132 are grouped. Moreover, it is possible that within one subarray 107 only one second spectral filter 132 for a given wavelength range is present. However, according to further embodiments, 2024PF00871 10 several second spectral filters 132 for one wavelength range may be present.

[0052] As is illustrated in (ii) , a subarray 107 may include second spectral filters 132 for different wavelength ranges, wherein several second spectral filters 132 for the same wavelength range are present and grouped. For example, an array of e.g. 16 second pixels 103 may be divided into four groups of second pixels 103 comprising second spectral filters 132 for four different wavelength ranges or colors. Accordingly, there may be, for example, four second pixels 103 or second spectral filters 132 for the same wavelength range or color. The second pixels 103 for the same wavelength range may be grouped, e.g. in squares.

[0053] As is illustrated under (iii) , only one single second pixel 103 may be arranged isolated from further second pixels 103. In other words, exclusively first pixels 102 are arranged directly adjacent to one of the second pixels 103. Accordingly, the second pixels 103 are arranged as individual second pixels 103 in an array of first pixels 102.

[0054] As is shown in the left-hand portion of Fig. 1A, the single second pixel 103 or the subarray 107 of second pixels 103 may be distributed among the pixel array 100 at a regular pattern. Accordingly, starting from any position within the pixel array 100, a position of a second pixel 103 or a second pixel subarray 107 may be determined using an algorithm or an arrangement rule.

[0055] As is clearly to be understood, the implementations of (i) , (ii) and (iii) may be mixed among a pixel array. In this manner, multi-spectral or second pixels 103 may be distributed among a pixel array 100 so as to accomplish measurement of precise color information. As is further clearly to be understood, among a pixel array 100, the size of the second pixel subarrays 107 may 2024PF00871 11 vary, for example , in accordance with a position within the pixel array .

[0056] Fig . IB shows a top view of a pixel array 100 according to further embodiments . The left-hand portion of Fig . IB shows a top view of the pixel array 100 , and the right-hand portion of Fig . IB shows an enlarged view of a portion of the pixel array 100 comprising a second pixel 103 or a second pixel subarray 107 . The right-hand portion of Fig . IB is identical with the right-hand portion of Fig . 1A. Di f fering from embodiments illustrated in Fig . 1A, the second pixels 103 or the second pixel subarrays 107 are arranged at an irregular pattern .

[0057] Fig . 1C shows a top view of a pixel array 100 according to further embodiments . The pixel array 100 may be implemented in the manner as has been described above with reference to Fig . 1A or IB . In more detail , first spectral filters 131 are arranged at first positions . Moreover, second spectral filters 132 are arranged at some of the first positions . Accordingly, the pixel array 100 comprises first pixels 102 and second pixels 103 or second pixel subarrays 107 . The second pixels 103 or second pixel subarrays 107 may be arranged at a regular pattern or at an irregular pattern . Further elements are as described above with reference to Figs . 1A and IB . In addition, the pixel array 100 comprises a clear filter 105 wherein the clear filter 105 is transmissive for the wavelength range that is to be detected by the photosensitive elements of the pixels . The clear filter 105 is arranged at at least one of the first positions and defines a flicker detection pixel 104 .

[0058] Fig . ID shows a further top view of an image sensor 10 according to embodiments . The image sensor 10 comprises a pixel array 100 including a plurality of pixels 101 . The image sensor further comprises a first spectral filter set comprising a set of spec- 2024PF00871 12 tral filters 131 , wherein first positions of the pixel array 100 are assigned to a first pattern for the first spectral filters . The image sensor further comprises a clear filter 105 which is transmissive for the wavelength range to be detected by photosensitive elements of the pixels 100 . The clear filter 105 is arranged at at least one of the first positions to define a flicker detection pixel 104 . The first pixels correspond to pixels comprising a first spectral filter . Accordingly, as is illustrated in Fig . ID, the pixel array 100 comprises an array of first pixels 102 and at least one flicker detection pixel 104 which is arranged at an arbitrary position within the pixel array 100 instead of a first spectral filter . The image sensor 10 may comprise more than one clear filter 105 .

[0059] Fig . 2 shows a schematic view of components of an image sensor 10 according to embodiments . The image sensor 10 comprises a pixel array 100 which may be similar to the pixel array that has been described herein above with reference to Figs . 1A and IB . The image sensor 10 further comprises a row control line 120 for addressing rows of the pixels 101 . Moreover, the image sensor 10 further comprises column output lines 121 for reading out signals from the respective pixels 101 . The pixel signals correspond to a charge generated by the photosensitive elements in response to electromagnetic radiation being incident . As is indicated, each of the pixels may comprise a photosensitive element 109 , e . g . a photodiode that may be connected via an associated circuitry to the row control line 120 and the column output line 121 . The image sensor 10 comprises a readout circuit 123 which is connected to the column output lines 121 to read out the signals from the pixels 101 . The image sensor 10 may further comprise vertical access circuitry 128 that may be connected and associated to the row control lines 120 . Moreover, the image sensor 10 may comprise hori zontal access circuitry 127 which is connected to the column output lines 121 . 2024PF00871 13

[0060] The pixel array 100 may comprise first pixels 102 and second pixels 103 as has been described above . Further, the pixel array 100 may comprise flicker detection pixels 104 , e . g . in addition to the second pixels 103 . According to further embodiments , the pixel array 100 may comprise first pixels 102 and flicker detection pixels 104 , wherein second pixels 103 are absent from the pixel array . The flicker detection pixel 104 comprises a clear filter 105 as has been described above .

[0061] Any of the second pixels 103 and the flicker detection pixel 104 may be integrated within the pixel array 100 as has been described above .

[0062] For example , the image sensor 10 may be operable in an image capturing mode and an ambient light sensing mode . Further, when the pixel array 100 incudes a flicker detection pixel 104 , the image sensor may be further operable in a flicker detection mode .

[0063] For example , in the ambient light sensing mode only second pixels 103 are addressed, e . g . by corresponding drivers . Moreover, the readout circuit 123 may be configured to readout pixel signals from exclusively the second pixels 103 . In an image capturing mode , the readout circuit 123 may be configured to readout pixel signals from exclusively the first pixels 102 .

[0064] The image sensor 10 may further comprise a control unit 126 that may be connected to the readout circuit 123 . The control unit 126 may be configured to determine a color temperature , e . g . at di f ferent positions of the pixel array 100 based on readout values of the second pixels 103 . For example , the control unit 126 may be configured to determine white balance values for the 2024PF00871 14 different positions of the pixel array 100. For example, the control unit 126 may be operable to average read out signals from the second pixels 103, e.g. from second pixels 103 comprising identical or similar second filters 132. For example, averaging may result in lower noise.

[0065] As is described, the color sensor is integrated in the CMOS image sensor 10. In more detail, second pixels 103 comprising a spectral filter of the second spectral filter set are integrated within the pixel array 100 for capturing an image. Accordingly, a second aperture or optics is not necessary for determining a precise color information. Since the pixel architecture is not changed, there will be only minimal to no image artifacts from an electrical point of view.

[0066] The image sensor 10 may be further configured to be operated in a flicker readout mode. For example, during the flicker readout mode exclusively pixel signals from the at least one flicker detection pixel 104 are read out. For example, the flicker detection pixel 104 may be read out at a high speed, e.g. more than 500 Hz, so as to enable detection of flicker up to or higher than 1000 Hz. For example, flicker detection pixels 104 have a dedicated readout that is operated at high readout rate compared to other pixel readout, i.e. the readout of the first pixels 102. Accordingly, the flicker detection pixels 104 may be sampled more often than the first pixels 102. For example, a flicker readout circuit 124 may be connected to the flicker detection pixel (s) 104 and may be configured to read out the flicker detection pixel (s) 104. The flicker detection pixels 104 may be configured to detect a flickering light source. When a flickering light source is detected by the flicker detection pixels 104, the image capture through the first pixels 101 may be synchronized with the flicker rate of the flickering light source. For example, this may be accomplished by correspondingly setting 2024PF00871 15 start and stop time for shutter time, also called integration time. The control unit 126 may be connected to the flicker readout circuit 124 and may be operable to synchronize the image capture through the first pixels 101 with the flicker rate of the flickering light source. As a consequence, aliasing and image artifacts may be reduced or avoided.

[0067] Fig. 3 shows a vertical cross-sectional view of a portion of the pixel array 100. The pixel array 100 comprises a CMOS substrate 118 in which a plurality of photosensitive elements 109 and corresponding circuitry may be arranged. Moreover, first and second spectral filters 131, 132 are arranged over the photosensitive elements 109. Depending on whether the spectral filters 108 are first spectral filters 131 or second spectral filters 132, the respective pixels are first pixels 102 or second pixels 103. As is illustrated in Fig. 3, the second pixels 103 may be grouped to form a second pixel subarray 107. Moreover, a microlens array 110 may be arranged over the first pixels 102. According to embodiments, a diffuser 111 may be arranged over the second pixels 103. In more detail, the diffuser 111 may be a structured diffuser. Due to the use of the diffuser 111, the light may be mixed between the different second pixels 103 or channels. As a result, color measurement may be improved.

[0068] Figs. 4A to 4C are vertical cross-sectional views of a workpiece 11 when performing a method of manufacturing an image sensor according to embodiments.

[0069] Fig. 4A shows a CMOS substrate 118 in which e.g. a plurality of photosensitive elements 109 and corresponding circuitry may be formed. Moreover, the first spectral filters may be arranged over the CMOS substrate 118. Further, a clear field 115 is left. In more detail within the clear field 115, the CMOS substrate 118 is not covered. Moreover, a microlens array 110 may be ar- 2024PF00871 16 ranged over the first spectral filters 131. Additionally, a plurality of second filters 132 have been formed, e.g. by depositing thin dielectric layers so as to form a reflective layer stack. The second filters 132 have been formed over a carrier substrate 119. The second filters 132 may be grouped in accordance with second pixel subarrays to be formed in the pixel array. For example, the second filters 132 may be arranged in a densely packed fashion to optimize area usage. Moreover, a lateral structuring may be accomplished, e.g. using lift-off or dry etch. In more detail, as is illustrated in Fig. 4B, the second filters 132 are attached to the carrier substrate 119 by means of small substrate portions so that they may be easily detached from the carrier substrate 119.

[0070] As is illustrated in Fig. 4C, a mass transfer process (pTP, LIFT) may be used for transferring the arrays of second filters 132 to the CMOS substrate 118. For example, this may be accomplished based on predisposed arrays of multiple colors or in multiple transfer steps for individual second filters 132. For example, a transfer stamp may be used for transferring the second filters 132 to the CMOS substrate 118. After transferring the second filters 132 to the CMOS substrate 118, a further microlens array 110 may be arranged over the second filters 132. According to further implementations, a diffuser 111 may be arranged over the second filter 132 so as to provide the pixel array 100 illustrated in Fig. 3, for example.

[0071] Fig. 4D summarizes a method according to embodiments. Noch einfugen. As is illustrated, a method of manufacturing an image sensor comprises providing (S100) an array of photosensitive elements over a CMOS substrate, arranging (Slid) first spectral filters of a first spectral filter set at first positions of the array of photosensitive elements in accordance with a first pattern for the first spectral filters, thereby 2024PF00871 17 defining first pixels, arranging (S120) second spectral filters of a second spectral filter set over the photosensitive elements thereby defining second pixels. A number of the first pixels is larger than the number of the second pixels. Accord- ing to embodiments, the sequence of steps S110 and S120 may be arbitrary. In more, detail, step S110 may be performed before step S120 or vice versa.

[0072] While embodiments of the invention have been described above, it is obvious that further embodiments may be implemented. For example, further embodiments may comprise any subcombination of features recited in the claims or any subcombination of elements described in the examples given above. Accordingly, this spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein .

[0073] 2024PF00871 18

[0074] LIST OF REFERENCES

[0075] 10 image sensor

[0076] 11 workpiece

[0077] 15 output signal

[0078] 100 pixel array

[0079] 101 pixel

[0080] 102 first pixel

[0081] 103 second pixel

[0082] 104 flicker detection pixel

[0083] 105 clear filter

[0084] 107 second pixel subarray

[0085] 108 spectral filter

[0086] 109 photosensitive element

[0087] 110 microlens array

[0088] 111 di f fuser

[0089] 115 clear field

[0090] 118 CMOS substrate

[0091] 119 carrier substrate

[0092] 120 row control line

[0093] 121 column output line

[0094] 123 readout circuit

[0095] 124 flicker readout circuit

[0096] 126 control unit

[0097] 127 hori zontal access circuitry

[0098] 128 vertical access circuitry

[0099] 131 first filter

[0100] 132 second filter

Claims

2024PF00871 19CLAIMS1. An image sensor (10) , comprising a pixel array (100) including a plurality of pixels (101) ; a first spectral filter set comprising a set of first spectral filters (131) , first positions of the pixel array (100) being assigned to a first pattern for the first spectral filter set, the image sensor (10) further comprising a second spectral filter set comprising a set of second spectral filters (132) , wherein the first spectral filters (131) are different from the second spectral filters (132) and the second spectral filters (132) are arranged at some of the first positions, wherein first pixels (102) correspond to pixels comprising a first spectral filter (131) and second pixels (103) correspond to pixels comprising a second spectral filter (132) , a number of the first pixels (102) being larger than the number of the second pixels (103) .

2. The image sensor (10) according to claim 1, wherein exclusively first spectral filters (131) are arranged directly adjacent to each of the second spectral filters (132) .

3. The image sensor (10) according to claim 1, wherein a plurality of second spectral filters (132) are grouped to form a subarray (107) .

4. The image sensor (10) according to claim 3, wherein the plurality of second spectral filters (132) include different spectral filters, so that each of the second spectral filters (132) is directly adjacent exclusively to different second spectral filters (132) .2024PF00871 205. The image sensor (10) according to claim 3, wherein the plurality of second spectral filters (132) include second spectral filters (132) being transmissive for different wavelength ranges, wherein the second spectral filters (132) for identical wavelength ranges are grouped.

6. The image sensor (10) according to any of claims 3 to5, further comprising a diffuser (111) arranged on a side of the second spectral filters (132) remote from a detection portion (109) of the associated pixel (101) .

7. The image sensor (10) according to any of the preceding claims, wherein positions of the second spectral filters (132) are arranged at a regular second pattern.

8. The image sensor (10) according to any of claims 1 to6, wherein positions of the second spectral filters (132) are arranged at an irregular second pattern.

9. The image sensor (10) according to any of the preceding claims, further comprising a readout circuit (123) being configured to read out pixel signals from the pixels (101) , the image sensor (10) being operable in an image capturing mode and an ambient light sensing mode.

10. The image sensor (10) according to claim 9, wherein in the ambient light sensing mode only second pixels (103) are addressed, and the readout circuit (123) is configured to readout pixel signals from exclusively the second pixels (103) .

11. The image sensor (10) according to claim 9 or 10, further comprising a control unit (126) configured to determine a2024PF00871 21 color temperature at different positions of the pixel array (100) based on readout values read out during the ambient light sensing mode.

12. The image sensor (10) according to claim 11, wherein the control unit (126) is further configured to determine white balance values for the different positions of the pixel array (100) .

13. The image sensor (10) according to any of the preceding claims, further comprising a clear filter (105) , the clear filter (105) being transmissive for a wavelength range to be detected by photosensitive elements (109) of the pixels (101) , wherein the clear filter (105) is arranged at at least one of the first positions, thereby defining a flicker detection pixel .

14. The image sensor (10) according to claim 13, further comprising a flicker readout circuit (124) , the image sensor (10) being further configured to be operated in a flicker readout mode, wherein in the flicker readout mode the flicker readout circuit (124) is configured to readout pixel signals from exclusively the flicker detection pixels (104) .

15. The image sensor (10) according to any of the preceding claims, wherein a number of spectral filters (131) of the first spectral filter set is smaller than the number of spectral filters (132) of the second spectral filter set.

16. A method of manufacturing an image sensor (10) comprising : providing (S100) an array of photosensitive elements (109) over a CMOS substrate (118) ;2024PF00871 22 arranging (Slid) first spectral filters (131) of a first spectral filter set at first positions of the array of photosensitive elements (109) in accordance with a first pattern for the first spectral filters (131) , thereby defining first pixels (102) , arranging (S120) second spectral filters (132) of a second spectral filter set over the photosensitive elements (109) thereby defining second pixels (103) , wherein a number of the first pixels (102) is larger than the number of the second pixels (103) .

17. The method according to claim 16, wherein the second spectral filters (132) are formed over a carrier substrate (119) , and arranging the second spectral filters (132) comprises transferring the second spectral filters (132) to the array of photosensitive elements (109) .

18. The method according to claim 17, wherein the second spectral filters (132) are transferred using a mass transfer process .

19. An image sensor (10) , comprising a pixel array (100) including a plurality of pixels (101) ; a first spectral filter set comprising a set of first spectral filters (131) , first positions of the pixel array 100 being assigned to a first pattern for the first spectral filters ( 131 ) , the image sensor (10) further comprising a clear filter (105) , the clear filter (105) being transmissive for a wavelength range to be detected by photosensitive elements (109) of the pixels (101) , wherein the clear filter (105) is arranged at at least one of the first positions to define flicker detection pixels2024PF00871 23(104) , wherein first pixels (103) correspond to pixels comprising a first spectral filter (131) .

20. The image sensor (10) according to claim 19, further comprising a flicker readout circuit (124) , the image sensor (10) being further configured to be operated in a flicker readout mode, wherein in the flicker readout mode the flicker readout circuit (124) is configured to readout pixel signals from exclusively the flicker detection pixels (104) .

21. The image sensor (10) according to claim 19, further comprising a control unit (126) configured to synchronize an image capturing process performed by the first pixels (102) with a flicker rate of a light source when a flickering has been detected.

Images