Narrowband filters with high permeability

Abstract

Image sensor, comprehensive: a substrate (1102), a photodetector (802) in the substrate (1102), and a filter (102) located above the photodetector (802) and comprising the following: a first Bragg mirror, DBR (104), a second DBR (106), a defect layer (108) between the first (104) and the second (106) DBR and a plurality of column structures (110) extending through the first and second DBR (104, 106) and the defect layer (108), wherein the column structures (110) are arranged in a periodic pattern and have a refractive index that differs from a refractive index of the defect layer (108).

Description

BACKGROUND

[0001] A variety of devices include photodetectors for detecting incident radiation. For example, a complementary metal-oxide-semiconductor (CMOS) image sensor may include an array of photodetectors to convert an optical image into digital data representing the optical image. However, photodetectors typically have little or no ability to distinguish between radiation of different wavelengths (or colors). Therefore, photodetectors can be combined with filters to allow the photodetectors to detect radiation of specific wavelengths.

[0002] KR 10 2018 0 021 614 discloses an optical filter with first and second reflection layers separated from each other by a dielectric region. The dielectric region has alternating refractive indices and a buffer layer.

[0003] EP 1592 067 A1 discloses a solid-state imaging device with a color filter that selectively transmits incident light. The color filter comprises two λ / 4 multilayer films and an insulating layer disposed between the two λ / 4 multilayer films. Here, each of the λ / 4 multilayer films consists of several dielectric layers, and the optical thickness of the insulating layer is not λ / 4. Since this color filter has a small thickness, the solid-state imaging device is small in size. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Aspects of the present disclosure will be best understood by considering the following detailed description and the accompanying drawings. It is noted that, in accordance with standard industry practice, various features are not to scale. The dimensions of the various features may be exaggerated or reduced arbitrarily for clarity. Fig. 1 illustrates a cross-sectional view of an illustrative example of a narrowband filter having a periodic array of columnar structures confined to a defect layer. Fig. 2A to 2E illustrated cross-sectional views of various illustrative examples of the narrow band filter of Fig. 1 with different configurations of the defect layer. Fig. 3A to 3E illustrate cross-sectional views of some embodiments of the respective narrowband filters of the Fig. 2A to 2E, in which the pillar structures extend through a first and a second multilayer film and the defect layer. Fig. Figure 4 illustrates a graph of some embodiments in which a curve plots transmittance versus wavelength for the narrowband filter in one of the Fig. 2A to 2E and 3A to 3E. Fig. 5A to 5D illustrate cross-sectional views of some illustrative examples and embodiments of the narrow band filters of the Fig. 2A and Fig. 3A, in which the columnar structures have tapered widths. Fig. 6A and Fig. 6B illustrate cross-sectional views of some alternative illustrative examples and embodiments of the narrow band filters of the Fig. 2A and Fig. 3A, in which columnar cavities are used instead of columnar structures. Fig. 7A to 7G illustrate head-end floor plans of various embodiments of the column structures in one of the Fig. 1, 2A to 2E, 3A to 3E and 5A to 5D. Fig. Figure 8 illustrates a cross-sectional view of a narrow band filter of the Fig. 3A, wherein the narrowband filter 102 has a first region and a second region with different fill factors for the column structures. Fig. 9A and Fig. 9B illustrate cross-sectional views of various embodiments of the integrated chip of Fig. 8, where the integrated chip includes absorptive color filters. Fig. 10A to 10C illustrate cross-sectional views of various embodiments of the integrated chip of Fig. 8, where the integrated chip includes a low-pass or high-pass filter. Fig. 11A to 11D illustrate cross-sectional views of various illustrative examples and embodiments of the integrated chip of Fig. 8, where the narrowband filter has additional regions, each with different filling factors for the column structures. Fig. 12 to 15, 16A to 16D, and 17A to 17C illustrate a sequence of cross-sectional views of various illustrative examples and embodiments of a method for forming a backside illuminated (BSI) integrated image chip including a narrowband high transmittance filter. Fig. Figure 18 illustrates a block diagram of some embodiments of the method of Fig. 12 to 15, 16A to 16D and 17A to 17C. Fig. 19, Fig. 20, Fig. 21A and Fig. 21B illustrate a sequence of cross-sectional views of various illustrative examples and embodiments of a method for forming a front-side illuminated (FSI) integrated image chip including a narrowband high transmittance filter. Fig. Figure 22 illustrates a block diagram of some embodiments of the method of Fig. 19, Fig. 20, Fig. 21A and Fig. 21B. DETAILED DESCRIPTION

[0005] The present disclosure provides many different embodiments or examples for implementing various features of this disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. For example, in the following description, the formation of a first feature over or on a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed that lie between the first and second features such that the first and second features may not be in direct contact. Furthermore, in the present disclosure, reference numbers and / or letters may be repeated in the various examples.This repetition is for the purpose of simplicity and clarity and does not in itself imply a relationship between the various embodiments and / or configurations discussed.

[0006] Furthermore, terms of spatial relationships such as "beneath," "below," "lower," "above," and "upper" are used herein for convenience of description to describe a relationship of one element or structural element relative to one or more other elements or structural elements as illustrated in the figures. These terms of spatial relationships are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be oriented differently (rotated 90 degrees or in other orientations), and the spatial relationship descriptions used herein may be interpreted analogously.

[0007] One type of wavelength filter is an absorptive filter. An absorptive filter is a filter made of a material that absorbs some wavelengths of radiation while transmitting others. An absorptive filter is limited by the available materials, so it can be difficult to control the properties of the absorptive filter. For example, it can be difficult to achieve a narrow transmission band. A narrow transmission band, for example, might be a transmission band with a width of less than about 50 nanometers.

[0008] Another type of wavelength filter is a microcavity filter. A microcavity comprises a pair of metal plates and a thin film sandwiched between the metal plates. The thin film defines a microcavity within which buildup interference occurs for wavelengths within the transmission band and cancellation interference occurs for wavelengths outside the transmission band. However, despite buildup interference for wavelengths within the transmission band, the microcavity filter has only weak transmission due to absorption by the metal plates. Furthermore, by varying the thickness of the thin film, the transmission band of the microcavity filter is shifted. However, in image sensors and other devices, multiple wavelength filters with different transmission bands are often used together.This results in a plurality of masks to adjust thicknesses of the different wavelength filters and thus to high costs, since masks are expensive.

[0009] Another type of wavelength filter is a plasmonic filter, which uses a metal nanostructure with a periodic pattern. For example, a plasmonic filter can comprise a metal nanograting. The metal nanostructure filters radiation wavelengths through the surface plasmon effect and can be tuned by varying the pitch of the periodic structure. However, the spectrum of a plasmonic filter strongly depends on the radiation incidence angle, which limits the application of the plasmonic filter.

[0010] Various embodiments of the present application are directed to a narrowband high-transmittance filter. In some embodiments, the filter comprises a first Bragg mirror (DBR), a second DBR, a defect layer between the first and second DBRs, and a periodic array of pillar structures. The pillar structures extend through the defect layer and have a refractive index that differs from a refractive index of the defect layer. The first and second DBRs create a low-transmittance band, and the defect layer creates a high-transmittance band that divides the low-transmittance band. Depending on a refractive index of the pillar structures and a fill factor (e.g., total volume) of the pillar structures, the pillar structures shift the high-transmittance band toward lower or higher wavelengths.

[0011] Because of the pillar structures, the position of the high-transmittance band is highly controllable. Furthermore, a single mask can be used to form the filter with multiple different high-transmittance bands, each in different regions of the filter. For example, the fill factor of the pillar structures can be high in a first region of the filter and low in a second region of the filter, so that the first and second regions have different high-transmittance bands. Furthermore, due to the use of the defect layer to create the high-transmittance band, the high-transmittance band can be narrow. Furthermore, since the first and second DBRs can be formed without absorptive materials (e.g., metal or another absorptive material), high transmittance can be achieved at the high-transmittance band.

[0012] According to Fig. 1, a cross-sectional view 100 of a high-transmittance narrowband filter 102 is provided according to an illustrative example. The narrowband filter 102 may also be referred to, for example, as a photonic crystal filter. A first multilayer film 104 alternates from top to bottom between a first refractive index and a second refractive index, and a second multilayer film 106 alternates from top to bottom between the first refractive index and the second refractive index. In some embodiments, the first and second multilayer films 104, 106 are or define DBRs. For example, the first multilayer film 104 may be a first DBR and the second multilayer film 106 may be a second DBR. In some embodiments, the first and second multilayer films 104 are formed from transparent materials and / or materials with low absorption for wavelengths transmitted by the narrowband filter 102.Low absorption can, for example, be below approximately 30%, 20%, or 10%. However, other materials and / or absorption levels are also possible.

[0013] A defect layer 108 is located between the first and second multilayer films 104, 106. In some embodiments, the defect layer 108 has a different refractive index than the first and second refractive indices of the first and second multilayer films 104, 106. In some embodiments, a thickness Td of the defect layer 108 differs from individual layers (not shown) of the first and second multilayer films 104, 106, which have the first refractive index. In some such embodiments, the defect layer 108 has the first refractive index. In some embodiments, the thickness Td of the defect layer 108 differs from individual layers (not shown) of the first and second multilayer films 104, 106, which have the second refractive index. In some such embodiments, the defect layer 108 has the second refractive index.In some embodiments, the thickness Td of the defect layer 108 is between about 30 and 600 nanometers. However, other thicknesses for the defect layer 108 are also possible.

[0014] A plurality of pillar structures 110 extend through the defect layer 108 from a top or head side of the defect layer 108 to a bottom or bottom side of the defect layer. For clarity, only some of the pillar structures 110 are labeled 110. Furthermore, the pillar structures 110 are present in one or more periodic patterns and have a different refractive index than the first and second refractive indices of the first and second multilayer films 104, 106. For example, the refractive index of the pillar structures 110 can be higher or lower than the first and second refractive indices of the first and second multilayer films 104, 106.In some embodiments, each of the pillar structures 110 has: 1) the refractive index, 2) the same width Wc as any other of the pillar structures 110, 3) the same material composition as any other of the pillar structures 110, 4) or a combination of the above. The width Wc of the pillar structures 110 may, for example, be about 20 to 200 nanometers, although other values ​​are also contemplated. In some embodiments, the pillar structures 110 are in an array and / or are evenly spaced with a pitch Pc. The pitch Pc may, for example, be about 40 to 800 nanometers, although other pitches are also contemplated.

[0015] During use of the narrowband filter 102, radiation 112 is received at a filter front 114 and selectively transmitted to a filter back 116 through constructive and canceling interference of reflections at interfaces between materials with different refractive indices. The filter front 114 can be defined, for example, by the second multilayer film 106. The filter back 116 can be defined, for example, by the first multilayer film 104.

[0016] The first and second multilayer films 104, 106 define a low-transmittance band (i.e., a wavelength range) in which the transmittance from the filter front 114 to the filter back 116 is low. Low transmittance can, for example, be a transmittance below approximately 40%, 30%, or 20%. However, other transmittances are also possible. The defect layer 108 defines a high-transmittance band (i.e., a wavelength range) in which the transmittance from the filter front 114 to the filter back 116 is high. The high-transmittance band is narrow and divides the low-transmittance band into segments between an upper and a lower limit of the low-transmittance band.A narrow passband may, for example, be a passband with a width of less than about 20, 35, or 50 nanometers, and / or a high transmittance may, for example, be a transmittance above about 80%, 90%, or 95%. Other widths and / or transmittances are also contemplated. In some embodiments, the low- and high-transmittance bands shift toward lower wavelengths as the average angle of incidence for radiation 112 increases.

[0017] The pillar structures 110 shift the position of the high-transmittance band based on the refractive index of the pillar structures 110 and a fill factor of the pillar structures 110. The fill factor can be, for example, the total volume occupied by the pillar structures 110 and can be varied, for example, by changing the size of the pillar structures 110, a spacing between the pillar structures 110, the shape of the pillar structures 110, another property of the pillar structures 110, or a combination of the above. If the pillar structures 110 have a refractive index that is lower than the first and second refractive indices of the first and second multilayer films 104, 106, then increasing the fill factor shifts the high-transmittance band toward lower wavelengths, and decreasing the fill factor shifts the high-transmittance band toward higher wavelengths.If the pillar structures 110 have a refractive index that is greater than the first and second refractive indices of the first and second multilayer films 104, 106, then increasing the fill factor shifts the high-transmittance band toward higher wavelengths and decreasing the fill factor shifts the high-transmittance band toward lower wavelengths.

[0018] Due to the pillar structures 110, the position of the high-transmittance band is highly controllable. Furthermore, due to the use of the defect layer 108 to define the high-transmittance band, the high-transmittance band can be narrow. Furthermore, since the first and second multilayer films 104, 106 can be formed with clear materials and / or with materials with low absorption for wavelengths transmitted by the narrowband filter 102, high transmittance can be achieved at the high-transmittance band.

[0019] According to Fig. 2A is a cross-sectional view 200A of some more detailed embodiments of the narrowband filter 102 of Fig. 1, in which the defect layer 108 has the first refractive index of the first and second multilayer films 104, 106 and further has a thickness Td that is greater than thicknesses of individual layers of the first and second multilayer films 104, 106, respectively. The first multilayer film 104 comprises one or more first layers 202 and one or more second layers 204, and the second multilayer film 106 comprises one or more third layers 206 and one or more fourth layers 208.

[0020] The one or more first layers 202 are alternately layered (or interleaved) with the second layer(s) 204, and the one or more third layers 206 are alternately layered (or interleaved) with the fourth layer(s) 208. Each of the first and third layers 202, 206 has: 1) the first refractive index, 2) the same thickness Tf as any other of the first and third layers 202, 206, 3) the same material composition as any other of the first and third layers 202, 206, 4) or a combination of the foregoing. Each of the second and fourth layers 204, 208 has: 1) the second refractive index, 2) the same thickness Ts as any other of the second and fourth layers 204, 208, 3) the same material composition as any other of the second and fourth layers 204, 208, 4) or a combination of the foregoing.The first refractive index may, for example, be approximately 1.0 to 1.5, and the second refractive index may, for example, be approximately 1.7 to 4.5, or vice versa. However, other values ​​are also possible. Furthermore, the first refractive index may, for example, be greater than the second refractive index, or vice versa. The first, second, third, and fourth layers 202, 204, 206, 208 may, for example, be or comprise materials with low absorption for transmittable wavelengths, transparent materials, dielectric materials, or a combination of the above.

[0021] The defect layer 108 is located between the first and second multilayer films 104, 106 such that a bottom side of the defect layer 108 is adjacent to one of the one or more second layers 204 and a top side of the defect layer 108 is adjacent to one of the one or more fourth layers 208. The defect layer 108 has a thickness Td that differs from the thickness Tf of the first and third layers 202, 206. For example, the thickness Td of the defect layer 108 may be greater than the thickness Tf of the first and third layers 202, 206. As another example, the thickness Td of the defect layer 108 may be less than the thickness Tf of the first and third layers 202, 206. In some embodiments, the thickness Td of the defect layer 108 may also differ from (e.g., be greater or lesser) the thickness Ts of the second and fourth layers 204, 208.Furthermore, the defect layer 108 has the same material composition and / or the same refractive index as the first and third layers 202, 206.

[0022] In some embodiments, each of the first and third layers 202, 206 is or comprises silicon oxide (e.g., SiO2) and each of the second and fourth layers 204, 208 is or comprises titanium oxide (e.g., TiO2) such that the second and fourth layers 204, 208 have a higher refractive index than the first and third layers 202, 206. In some such embodiments, the defect layer 108 is or comprises silicon oxide as well. In further embodiments, each of the first and third layers 202, 206 is or comprises titanium oxide and each of the second and fourth layers 204, 208 is or comprises silicon oxide as well such that the second and fourth layers 204, 208 have a lower refractive index than the first and third layers 202, 206. In some such embodiments, the defect layer 108 is or comprises titanium oxide as well.Notwithstanding the use of silicon oxide and titanium oxide for the preceding embodiments, other materials may also be used for the defect layer 108 and the first, second, third and fourth layers 202, 204, 206, 208.

[0023] In some embodiments, each of the first and third layers 202, 206 has a thickness Tf of about 25 to 300 nanometers, and each of the second and fourth layers 204, 208 has a thickness Ts of about 15 to 200 nanometers. Such embodiments may arise, for example, when the first and third layers 202, 206 are or comprise silicon oxide and the second and fourth layers 204, 208 are or comprise titanium oxide. In some embodiments, each of the first and third layers 202, 206 has a thickness Tf of about 15 to 200 nanometers, and each of the second and fourth layers 204, 208 has a thickness Ts of about 25 to 300 nanometers. Such embodiments may arise, for example, when the first and third layers 202, 206 are or comprise titanium oxide and the second and fourth layers 204, 208 are or comprise silicon oxide.Without prejudice to the thickness values ​​for the preceding embodiments, other thickness values ​​are also possible for the first, second, third and fourth layers 202, 204, 206, 208.

[0024] According to Fig. 2B is a cross-sectional view 200B of some alternative embodiments of the narrowband filter 102 of Fig. 2A, in which the defect layer 108 has a thickness Td that is less than the thicknesses of individual layers of the first and second multilayer films 104, 106, respectively.

[0025] According to Fig. 2C is a cross-sectional view 200C of some alternative embodiments of the narrowband filter 102 of Fig. 2A, in which the defect layer 108 has a refractive index that differs from the first and second refractive indices of the first and second multilayer films 104, 106. For example, the refractive index of the defect layer 108 may be smaller or larger than the first and second refractive indices of the first and second multilayer films 104, 106. Furthermore, the defect layer 108 has a material composition that differs from the first, second, third, and fourth layers 202, 204, 206, 208.

[0026] In some embodiments, the first and second refractive indices of the first and second multilayer films 104, 106 differ from and are intermediate between the refractive index of the pillar structures 110 and the refractive index of the defect layer 108. In some embodiments, a bottom side of the defect layer 108 is adjacent to one of the one or more second layers 204, and a top side of the defect layer 108 is adjacent to one of the one or more third layers 206. In other embodiments, a bottom side of the defect layer 108 is adjacent to one of the one or more first layers 202, and a top side of the defect layer 108 is adjacent to one of the one or more fourth layers 208. In some embodiments, the thickness Td of the defect layer 108 is equal to the thickness Tf of the first and third layers 202, 206 and / or the thickness Ts of the second and fourth layers 204, 208.In other embodiments, the thickness Td of the defect layer 108 differs from the thickness Tf of the first and third layers 202, 206 and / or the thickness Ts of the second and fourth layers 204, 208.

[0027] According to Fig. 2D, a cross-sectional view 200D of some alternative embodiments of the narrowband filter 102 of Fig. 2C, in which the defect layer 108 has a refractive index that differs from the first and second refractive indices of the first and second multilayer films 104, 106, and further has a thickness Td that is greater than thicknesses of individual layers of the first and second multilayer films 104, 106, respectively.

[0028] According to Fig. 2E is a cross-sectional view 200E of some alternative embodiments of the narrowband filter 102 of Fig. 2C, in which the defect layer 108 has a refractive index that differs from the first and second refractive indices of the first and second multilayer films 104, 106, and further has a thickness Td that is less than thicknesses of individual layers of the first and second multilayer films 104, 106, respectively.

[0029] According to Fig. 3A to 3E, cross-sectional views 300A to 300E of some embodiments of the narrow bandpass filter 102 are provided in which the pillar structures 110 extend from a top or head side of the second multilayer film 106 to a bottom or bottom side of the first multilayer film 104 through the first and second multilayer films 104, 106 and the defect layer 108.

[0030] According to Fig. 4, a graph 400 of some embodiments is provided in which a curve 402 plots the transmittance versus wavelength for the narrowband filter 102 of the Fig. 2A to 2E and 3A to 3E. The first, second, third and fourth layers 202, 204, 206, 208 of the Fig. 2A to 2E and 3A to 3E define a low-permeability band 404. The sharpness of the low-permeability band 404 can be increased, for example, by increasing the number of first and second layers 202, 204 and / or by increasing the number of third and fourth layers 206, 208. The sharpness of the low-permeability band 404 can be, for example, the steepness of the curve 402 (e.g., the ratio of slope to horizontal distance) at the upper and lower boundaries of the low-permeability band 404.

[0031] The position of the low-permeability band 404 depends on the thicknesses Tf, Ts (see Fig. 2A to 2E and 3A to 3E) of the first, second, third, and fourth layers 202, 204, 206, 208 and the refractive indices of the first, second, third, and fourth layers 202, 204, 206, 208. For example, the central wavelength λ of the low-transmission band 404 may be: λ = 2(n1Tf+n2Ts) / m. n1 and n2 are the first refractive index of the first and third layers 202, 206 and the second refractive index of the second and fourth layers 204, 208, respectively. Tf and Ts are the thickness of the first and third layers 202, 206 and the thickness of the second and fourth layers 204, 208, respectively. m is the degree of optical sensitivity and is an integer greater than zero.

[0032] The width Δλ of the low-transmission band 404 depends on the central wavelength λ of the low-transmission band 404 (see above) as well as on the refractive indices of the first, second, third, and fourth layers 202, 204, 206, 208. For example, the width Δλ of the low-transmission band 404 can be: Δλ = λΔn / 2. Δn is the difference between the first refractive index of the first and third layers 202, 206 and the second refractive index of the second and fourth layers 204, 208.

[0033] The defect layer 108 of the Fig. 2A to 2E and 3A to 3E define a high-transmittance band 406 that divides the low-transmittance band 404 into an upper and a lower segment. For the defect layer 108, the high-transmittance band 406 may, for example, have an inverted bell shape or another suitable shape. With increasing thickness Td (see Fig. 2A to 2E and 3A to 3E) of the defect layer 108 and / or increasing refractive index of the defect layer 108, the maximum of the high-transmittance band 406 moves toward higher wavelengths. With decreasing thickness Td of the defect layer 108 and / or decreasing refractive index of the defect layer 108, the maximum of the high-transmittance band 406 further moves toward lower wavelengths. Although not shown, in some embodiments, increasing the thickness Td of the defect layer 108 may result in multiple high-transmittance bands. The central wavelength λt of such a high-transmittance band may, for example, be: λ tα (n3Td) / (t+0.5). Where n3 is the refractive index of the defect layer 108, and Td is the thickness of the defect layer 108. t is the index of the high-transmittance band. For example, if two high-transmittance bands are present, t = 1 would be used for the first high-transmittance band and t = 2 for the second high-transmittance band.

[0034] Depending on a refractive index of the column structures 110 and a fill factor of the column structures 110, the column structures 110 of the Fig. 2A to 2E and 3A to 3E, the maximum of the high-transmittance band 406 in the direction of lower or higher wavelengths. Furthermore, as noted above, the column structures 110 can be arranged with a pitch Pc (see Fig. 2A to 2E and 3A to 3E). In some embodiments, the spacing Pc is smaller than the wavelength at the maximum of the high-transmittance band 406 and / or smaller than the quotient resulting from dividing the wavelength at the maximum by the refractive index of the second and fourth layers 204, 208. By limiting the spacing Pc in this way, side maxima, for example, can be avoided. Side maxima are maxima on the side of the high-transmittance band 406 in the low-transmittance band 404 and can be caused, for example, by diffraction.

[0035] According to Fig. 5A is a cross-sectional view 500A of some embodiments of the narrowband filter 102 of Fig. 2A, in which the column structures 110 have tapered widths that decrease from top to bottom. For example, the column structures 110 may each have a head-side width Wc t, a floor-side width Wc b which is less than the head-end width Wc t , and side walls at an angle θ of less than about 90 degrees. In some embodiments, the head-end width Wc t about 0.2 to 0.3 micrometers or about 0.22 micrometers, the bottom width Wc b about 0.20 to 0.30 micrometers or about 0.20 micrometers, the angle θ about 80 to 89 degrees or about 87 degrees, or a combination of the above. However, other values ​​for the head-side width Wc are also possible. t , the floor width Wc b and the angle θ in question.

[0036] If the column structures 110 had the same head width Wc from top to bottom t , then the column structures 110 would have a first fill factor and the high-permeability band 406 (see Fig. 4) have a maximum at a first wavelength. If the column structures 110 had a uniform base width Wc from top to bottom, b , then the pillar structures 110 would have a second fill factor that is smaller than the first fill factor. Furthermore, due to the different fill factors, the high-transmittance band 406 would have a maximum at a second wavelength that is different from the first wavelength. Due to the tapered widths of the pillar structures 110, the pillar structures 110 have a third fill factor that lies between the first and second fill factors. The high-transmittance band 406 can then have a maximum at a third wavelength that lies between the first and second wavelengths. Tapering the widths of the pillar structures 110 thus allows additional control over the fill factor of the pillar structures 110 and the position of the maximum of the high-transmittance band 406.

[0037] According to Fig. 5B is a cross-sectional view 500B of some alternative embodiments of the narrowband filter 102 of Fig. 5A, in which widths of the pillar structures 110 increase from top to bottom. The pillar structures 110 may then, for example, each have sidewalls at an angle θ of greater than about 90 degrees. In some embodiments, the angle θ is about 91 to 100 degrees or another suitable value. However, if the angle θ is too large (e.g., greater than about 100 degrees or another suitable value), it may be difficult to deposit material of the pillar structures 110 into openings in which the pillar structures 110 are formed.

[0038] According to Fig. 5C and Fig. 5D, cross-sectional views 500C, 500D of some alternative embodiments of the narrowband filter 102 of Fig. 3A, in which the column structures 110 have tapered widths, as with respect to Fig. 5A and Fig. 5B, respectively. The column structures 110 of the Fig. 5C have tapered widths that decrease from top to bottom, as with respect to Fig. 5A. The column structures 110 of the Fig. 5D have tapered widths that increase from top to bottom, as with respect to Fig. 5B. In some embodiments, each of the column structures 110 further has a height Hc that is at least an order of magnitude greater than the head-end width Wc. t and / or the floor width Wc b The height Hc can, for example, be approximately 1.5 to 2.5 micrometers or approximately 2.0 micrometers. However, other values ​​for the height Hc are also possible.

[0039] Although the Fig. 5A to 5D show the column structures 110 with tapered widths using embodiments of the narrowband filter 102 in Fig. 2A and Fig. 3A, however, it should be noted that in other embodiments, the column structures 110 in each of the Fig. 1, 2B to 2E and 3B to 3E may have tapered widths. For example, the column structures 110 may be made of Fig. 2D have tapered widths that decrease from top to bottom, as with respect to Fig. 5A is illustrated and described.

[0040] According to Fig. 6A is a cross-sectional view 600A of some alternative embodiments of the narrowband filter 102 of Fig. 2A, in which columnar cavities 602 are used instead of the columnar structures 110. For clarity, only some of the columnar cavities 602 are labeled 602. The columnar cavities 602 may, for example, be evacuated, filled with air, filled with other suitable gases, or a combination of the above. The columnar cavities 602 also reduce material costs.

[0041] According to Fig. 6B is a cross-sectional view 600B of some alternative embodiments of the narrowband filter 102 of Fig. 3A, in which the columnar cavities 602 are used instead of the column structures 110.

[0042] Although the Fig. 6A and Fig. 6B the columnar cavities 602 using embodiments of the narrowband filter 102 in Fig. 2A and Fig. 3A, however, it should be noted that in other embodiments, the columnar cavities 602 in each of the Fig. 1, 2B to 2E, 3B to 3E and 5A to 5D. For example, the column structures 110 of Fig. 3D are replaced by the columnar cavities 602.

[0043] According to Fig. 7A is a plan view 700A of some embodiments of the column structures 110 in one of the Fig. 1, 2A to 2E, 3A to 3E and 5A to 5D. For example, the floor plan view 700A can be taken along the line AA' in Fig. 1, 2A to 2E, 3A to 3E, and 5A to 5D. The column structures 110 each have a circular footprint and are arranged in a plurality of rows and a plurality of columns to define an array. However, other footprints are also contemplated. The column structures 110 further fully fill the rows and columns. In some embodiments, each row of the array is spaced from each adjacent row by a spacing Pc and / or each column of the array is spaced from each adjacent column of the array by the spacing Pc.

[0044] According to Fig. 7B is a plan view 700B of some alternative embodiments of the column structures 110 of Fig. 7A, in which a width Wc of the column structures 110 is reduced. By reducing the width Wc of the column structures 110, the fill factor of the column structures 110 is reduced. By reducing the fill factor, the high-transmittance band of the narrowband filter 102 shifts relative to the high-transmittance band of Fig. 7A. For example, the high-permeability band shifts relative to the high-permeability band of Fig. 7A in the direction of higher wavelengths when the column structures 110 have a refractive index that is lower than the first and second refractive indices of the first and second multilayer films 104, 106 (see Fig. 1, 2A to 2E, 3A to 3E and 5A to 5D). As another example, the high-permeability band shifts relative to the high-permeability band of Fig. 7A towards lower wavelengths when the pillar structures 110 have a refractive index that is greater than the first and second refractive indices of the first and second multilayer films 104, 106.

[0045] According to Fig. 7C is a plan view 700C of some alternative embodiments of the column structures 110 of Fig. 7A, in which a width Wc of the column structures 110 is increased. By increasing the width Wc of the column structures 110, the fill factor of the column structures 110 is increased. By increasing the fill factor, the high-transmittance band of the narrowband filter 102 shifts relative to the high-transmittance band of Fig. 7A. For example, the high-permeability band shifts relative to the high-permeability band of Fig. 7A in the direction of lower wavelengths when the column structures 110 have a refractive index that is lower than the first and second refractive indices of the first and second multilayer films 104, 106 (see Fig. 1, 2A to 2E, 3A to 3E and 5A to 5D). As another example, the high-permeability band shifts relative to the high-permeability band of Fig. 7A towards higher wavelengths when the pillar structures 110 have a refractive index that is greater than the first and second refractive indices of the first and second multilayer films 104, 106.

[0046] According to Fig. 7D and Fig. 7E, plan views 700D, 700E of some alternative embodiments of the column structures 110 of Fig. 7A, in which a density of the column structures 110 is reduced or increased. In Fig. 7D, the density is reduced by removing column structures 110 such that the column structures 110 define a plurality of quincunx patterns 702. In Fig. 7E, the density of the column structures 110 is increased by adding column structures 110 such that the column structures 110 define a plurality of quincunx patterns 702. For clarity, in Fig. 7D and Fig. 7E, only some of the quincunx patterns 702 are labeled 702. In some embodiments, the quincunx patterns 702 are present in a plurality of rows and a plurality of columns, with each quincunx pattern 702 overlapping each quincunx pattern 702 in an adjacent row and each quincunx pattern 702 in an adjacent column.

[0047] By reducing or increasing the density of the column structures 110, the fill factor of the column structures 110 is reduced or increased, respectively. By reducing or increasing the fill factor, the high-transmittance band of the narrowband filter 102 shifts higher or lower, respectively, depending on a refractive index of the column structures 110. For further details, please refer to the explanations regarding Fig. 7B and Fig. 7C.

[0048] According to Fig. 7F and Fig. 7G, plan views 700F, 700G of some alternative embodiments of the column structures 110 of Fig. 7A, where the column structures 110 have different floor plan shapes. In Fig. 7F, the column structures 110 each have a triangular floor plan, wherein the three side lengths of the triangular floor plan correspond to the width Wc of Fig. 7A. The area of ​​the triangular plan is therefore smaller than that of the circular plan in Fig. 7A, and the column structures 110 have a smaller fill factor than in Fig. 7A. In Fig. 7G, the column structures 110 each have a square floor plan, wherein the four side lengths of the square floor plan correspond to the width Wc of Fig. 7A. The area of ​​the square floor plan is thus larger than that of the circular floor plan from Fig. 7A, and the column structures 110 have a larger fill factor than in Fig. 7A. By decreasing or increasing the fill factor, the high-transmittance band of the narrowband filter 102 shifts higher or lower, respectively, depending on the refractive index of the column structures 110. For further details, please refer to the explanations regarding Fig. 7B and Fig. 7C.

[0049] Although Fig. 7A to 7E show the column structures 110 with circular floor plans, but other floor plans are also possible. For example, in other embodiments, the column structures 110 in each of the Fig. 7A to 7E the triangular floor plan Fig. 7F, the square floor plan from Fig. 7G or another suitable floor plan. Furthermore, although the Fig. 7A to 7G on floor plans of the column structures 110 in Fig. 1, 2A to 2E, 3A to 3E and 5A to 5D, but the floor plans are also based on the columnar cavities 602 in Fig. 6A and Fig. 6B. In other embodiments, the column structures 110 may therefore be Fig. 7A to 7G through the columnar cavities 602 in Fig. 6A and Fig. 6B should be replaced.

[0050] According to Fig. 8 is a cross-sectional view 800 of some embodiments of a narrow band filter 102 of the Fig. 3A, in which the narrowband filter 102 has a first region 102a and a second region 102b with different fill factors for the column structures 110. For example, the first region 102a of the narrowband filter 102 may have a fill factor that is lower than that of the second region 102b of the narrowband filter 102. A fill factor for a region of the narrowband filter 102 may, for example, be the total volume of column structures 110 in the region.

[0051] Since the fill factor varies between the first and second regions 102a, 102b of the narrowband filter 102, the high-transmittance band of the narrowband filter 102 also varies between the first and second regions 102a, 102b. If the pillar structures 110 have a refractive index lower than those of the first and second multilayer films 104, 106, then increasing the fill factor shifts the high-transmittance band toward lower wavelengths, and decreasing the fill factor shifts the high-transmittance band toward higher wavelengths. If the pillar structures 110 have a refractive index higher than those of the first and second multilayer films 104, 106, then increasing the fill factor shifts the high-transmittance band toward higher wavelengths, and decreasing the fill factor shifts the high-transmittance band toward lower wavelengths.

[0052] In some embodiments, the first and second regions 102a, 102b of the narrowband filter 102 each have a head-end area of ​​more than about 4 square micrometers. For example, as the head-end area decreases, a transmittance may decrease. Below about 4 square micrometers, the transmittance may be too low for useful use. Such a low transmittance may, for example, be a transmittance below about 40%, 30%, or 20%. However, other low transmittances are also contemplated. In some embodiments, the first and second regions 102a, 102b of the narrowband filter 102 further correspond to pixel sensors. For example, the first and second regions 102a, 102b may correspond to pixel sensors with a one-to-one correspondence. However, other correspondences are also contemplated.The pixel sensors can be, for example, active pixel sensors (APSs) or other suitable pixel sensors.

[0053] Directly below the narrowband filter 102 are a plurality of photodetectors 802. A first group 802a of photodetectors 802 lies below the first region 102a of the narrowband filter 102, and a second group 802b of photodetectors 802 lies below the second region 102b of the narrowband filter 102. The photodetectors 802 may be, for example, or include photodiodes or other suitable photodetectors. Because the high-transmission band of the narrowband filter 102 varies between the first and second regions 102a, 102b of the narrowband filter 102, the narrowband filter 102 selectively transmits a first wavelength range to the first group 802a of photodetectors 802 and selectively transmits a second wavelength range to the second group 802b of photodetectors 802.For example, the narrowband filter 102 may transmit red radiation wavelengths to the first group 802a of photodetectors 802 via the first region 102a of the narrowband filter 102, while blocking blue radiation wavelengths via the first region 102a. As another example, the narrowband filter 102 may transmit blue radiation wavelengths to the second group 802b of photodetectors 802 via the second region 102b of the narrowband filter 102, while blocking red radiation wavelengths via the second region 102b.

[0054] In some embodiments, the photodetectors 802 are not capable of distinguishing radiation of different wavelengths. For example, the photodetectors 802 may be colorblind. Therefore, by selectively passing different wavelength ranges to the photodetectors 802 with the narrowband filter 102, the photodetectors 802 may detect radiation of specific wavelengths.

[0055] According to Fig. 9A is a cross-sectional view 900A of some alternative embodiments of the integrated chip of Fig. 8, in which absorptive color filters 902 are arranged above the narrowband filter 102. For example, first absorptive color filters 902a and second absorptive color filters 902b can be arranged above the narrowband filter 102 in an alternating pattern. The absorptive color filters 902 selectively transmit radiation of corresponding wavelengths while absorbing or otherwise blocking radiation of other wavelengths. For example, the first absorptive color filters 902a can selectively transmit radiation of first wavelengths (e.g., green wavelengths and / or other suitable wavelengths) while blocking radiation of other wavelengths (blue wavelengths and / or other suitable wavelengths). As a further example, the second absorptive color filters 902b can selectively transmit radiation of second wavelengths (e.g.,Blue wavelengths and / or other suitable wavelengths) while blocking radiation of other wavelengths (green wavelengths and / or other suitable wavelengths).

[0056] The absorptive color filters 902 help suppress radiation with wavelengths outside the high-transmittance band of the narrowband filter 102, so that such wavelengths do not reach the photodetectors 802. The photodetectors 802 therefore more accurately detect radiation within the high-transmittance band of the narrowband filter 102.

[0057] Furthermore, the absorptive color filters 902 together with the narrowband filter 102 allow more filter spectra to be generated than there are columnar fill factors. As mentioned above, when the thickness Td of the defect layer 108 is large, the narrowband filter 102 can achieve multiple high-transmittance bands. Therefore, for a given columnar fill factor, multiple high-transmittance bands can be generated by the narrowband filter 102, and the multiple high-transmittance bands can then be reduced by the absorptive color filters 902 to generate multiple filter spectra for the given columnar fill factor. For example, if the narrowband filter 102 has a single columnar fill factor and the thickness Td of the defect layer 108 is large enough to achieve four high-transmittance bands in the red, blue, and green wavelengths, respectively, the narrowband filter 102 can achieve four high-transmittance bands in the red, blue, and green wavelengths, respectively.To generate green radiation wavelengths, absorptive red, blue, and green color filters 902 can be combined with these bands to generate red, blue, and green filter spectra without having to vary a fill factor of the columnar structure 110. In some embodiments, two of the four high-transmittance bands are at blue radiation wavelengths, whereas the remaining high-transmittance bands are individually at red and green radiation wavelengths.

[0058] According to Fig. 9B is a cross-sectional view 900B of some alternative embodiments of the integrated chip of Fig. 9A, in which the absorptive color filters 902 are located between the photodetectors 802 and the narrowband filter 102.

[0059] According to Fig. 10A is a cross-sectional view 1000A of some alternative embodiments of the integrated chip of Fig. 8, in which a low-pass filter 1002 and a high-pass filter 1004 are layered over the narrowband filter 102. As illustrated, the high-pass filter 1004 lies above the low-pass filter 1002. However, in other embodiments, the low-pass filter 1002 may also lie above the high-pass filter 1004. The low-pass filter 1002 passes radiation with wavelengths below an upper limit to the narrowband filter 102 while blocking radiation with wavelengths above the upper limit. The high-pass filter 1004 passes radiation with wavelengths above a lower limit to the narrowband filter 102 while blocking radiation with wavelengths below the lower limit. The low-pass and high-pass filters 1002, 1004 help suppress radiation with wavelengths outside the high-pass band of the narrowband filter 102 so that such wavelengths do not reach the photodetectors 802.The photodetectors 802 therefore more accurately detect radiation within the high-transmittance band of the narrowband filter 102.

[0060] According to Fig. 10B and Fig. 10C are cross-sectional views 1000B, 1000C of some alternative embodiments of the integrated chip of Fig. 10A, where the high-pass filter 1004 or the low-pass filter 1002 is omitted. In Fig. 10B the high-pass filter 1004 is omitted. In Fig. 10C does not use the low-pass filter 1002.

[0061] Although Fig. 8, 9A, 9B and 10A to 10C using embodiments of the narrowband filter 102 in Fig. 3A, however, in other embodiments, embodiments of the narrowband filter 102 may also be implemented in one of the Fig. 1, 2A to 2E, 3B to 3E, 5A to 5D, 6A and 6B. Although Fig. 10A to 10C using embodiments of the integrated chip in Fig. 8, however, in other embodiments, embodiments of the integrated chip in one of the Fig. 9A and Fig. 9B can be used.

[0062] According to Fig. 11A is a cross-sectional view 1100A of some more detailed embodiments of the integrated chip of Fig. 8, in which the narrowband filter 102 additionally has a third region 102c and a fourth region 102d, each having different fill factors for the column structures 110. In the third region 102c of the narrowband filter 102, the fill factor of the column structures 110 is zero. In other words, the column structures 110 are not present in the third region 102c of the narrowband filter 102. In the fourth region 102d of the narrowband filter 102, the fill factor of the column structures 110 is greater than in the first and second regions 102a, 102b of the narrowband filter 102. Due to the different fill factors, the high-transmission band of the narrowband filter 102 differs in each of the first, second, third, and fourth regions 102a, 102b, 102c, 102d.

[0063] In some embodiments, the first, second, third, and fourth regions 102a, 102b, 102c, 102d define the colors of corresponding pixels in the integrated chip. As stated above, the photodetectors 802 are unable to distinguish radiation of different wavelengths and are thus colorblind. However, by coupling the photodetectors 802 to the first, second, third, and fourth regions 102a, 102b, 102c, 102d, radiation received by the photodetectors 802 is filtered by the associated regions of the narrowband filter 102 to include only the radiation transmitted by the associated regions. Therefore, the photodetectors 802 can each detect the different colors of the associated regions, and the pixels to which the photodetectors 802 belong can have individual color assignments.In some embodiments, the first region 102a may correspond to a white pixel, the second region 102b to a red pixel, the third region 102c to a green pixel, and the fourth region 102d to a blue pixel. In other embodiments, the first region 102a may correspond to a white pixel, the second region 102b to a blue pixel, the third region 102c to a green pixel, and the fourth region 102d to a red pixel. However, other correspondences are also contemplated.

[0064] The narrowband filter 102 is located on a top (or back) surface of a semiconductor substrate 1102, and semiconductor devices 1104 and an interconnect structure 1106 are located on a bottom (or front) surface of the semiconductor substrate 1102. For clarity, only some of the semiconductor devices 1104 are labeled 1104. Furthermore, the photodetectors 802 are located in the semiconductor substrate 1102, each underlying a single one of the first, second, third, and fourth regions 102a, 102b, 102c, 102d. As above, the photodetectors 802 may be or include, for example, photodiodes or other suitable photodetectors. The semiconductor substrate 1102 may be, for example, a bulk silicon substrate, another suitable bulk semiconductor substrate, a silicon-on-insulator (SOI) substrate, or another suitable semiconductor substrate.

[0065] The semiconductor devices 1104 are partially defined by the semiconductor substrate 1102 and may be, for example, metal-oxide-semiconductor field-effect devices (MOSFETs), other suitable metal-oxide-semiconductor (MOS) devices, other suitable insulated-gate field-effect transistors (IGFETs), other suitable semiconductor devices, or a combination of the foregoing. In some embodiments, the semiconductor devices 1104 and the photodetectors 802 jointly define pixel sensors individually for the first, second, third, and fourth regions 102a, 102b, 102c, 102d of the narrowband filter 102. The pixel sensors may be, for example, active pixel sensors or other suitable pixel sensors.In some embodiments, semiconductor devices 1104 include respective gate electrodes 1108, respective gate dielectric layers 1110, respective sidewall interposers 1112, respective source / drain regions (not shown), and respective selectively conducting channels (not shown). For clarity, only some of the gate electrodes 1108 are labeled 1108, only some of the gate dielectric layers 1110 are labeled 1110, and only some of the sidewall interposers 1112 are labeled 1112.

[0066] The source / drain regions and the selectively conducting channels are located in the semiconductor substrate 1102, and the gate electrodes 1108 are each located beneath the selectively conducting channels. The gate dielectric layers 1110 space the gate electrodes 1108 from the semiconductor substrate 1102 and thus from the selectively conducting channels. The sidewall spacers 1112 are located on sidewalls of the gate electrodes 1108. The gate electrodes 1108 may be or comprise, for example, doped polysilicon, metal, one or more other suitable conductive materials, or a combination of the foregoing. The gate dielectric layers 1110 may be or comprise, for example, silicon oxide, one or more other suitable dielectrics, or a combination of the foregoing.The sidewall spacers 1112 may be or include, for example, silicon oxide, silicon nitride, silicon oxynitride, one or more other suitable dielectrics, or a combination of the foregoing.

[0067] The interconnect structure 1106 comprises a dielectric interconnect layer 1114, a plurality of wires 1116, and a plurality of vias 1118. For clarity, only some of the wires 1116 are labeled 1116 and only some of the vias 1118 are labeled 1118. The wires 1116 and the vias 1118 are alternately layered in the dielectric interconnect layer 1114 to define conductive paths to the semiconductor devices 1104. The conductive paths may, for example, interconnect the semiconductor devices 1104 and / or provide electrical connections to the semiconductor devices 1104 from outside the integrated chip. The dielectric interconnect layer 1114 may, for example, be or comprise a low-κ dielectric, silicon oxide, one or more other dielectrics, or a combination of the foregoing.A low-κ dielectric as used herein may, for example, be or include a dielectric having a dielectric constant κ of less than about 3.9, 3, 2, or 1. The wires 1116 and the vias 1118 may, for example, be or include copper, aluminum, aluminum-copper, tungsten, one or more other suitable conductive materials, or a combination of the foregoing.

[0068] In some embodiments, an insulating layer 1120 covers the semiconductor substrate 1102 and extends into the top (or back) side of the semiconductor substrate 1102 to physically and electrically separate the photodetectors 802. The insulating layer 1120 may, for example, be or include silicon oxide, one or more other suitable dielectrics, an anti-reflective coating (ARC), or a combination of the above. In some embodiments, an insulating liner 1122 lines the top (or back) side of the semiconductor substrate 1102 and separates the insulating layer 1120 from the semiconductor substrate 1102. The insulating liner 1122 may, for example, be or include silicon oxide and / or one or more other suitable dielectrics. In some embodiments, a metal grid 1124 is located in the insulating layer 1120 to act as a guide for radiation passing through the narrowband filter 102 to the photodetectors 802.By acting as a radiation guide, the metal grid 1124 can, for example, reduce crosstalk between the photodetectors 802 and increase quantum efficiency. The metal grid 1124 can, for example, be or comprise copper, aluminum-copper, aluminum, one or more other suitable metals, or a combination of the foregoing.

[0069] According to Fig. 11B is a cross-sectional view 1100B of another example of the integrated chip of Fig. 11A, in which the narrowband filter 102 comprises the embodiments of Fig. 2A. The column structures 110 are thus limited to the defect layer 108.

[0070] According to Fig. 11C is a cross-sectional view 1100C of some alternative embodiments of the integrated chip of Fig. 11A, in which the connection structure 1106 is located between the semiconductor substrate 1102 and the narrowband filter 102. Fig. 11A can be considered, for example, as a back-illuminated (BSI) image sensor, whereas Fig. 11C, for example, can be considered a front-side illuminated (FSI) image sensor. In some embodiments, isolation structures 1126 extend into the semiconductor substrate 1102 between the photodetectors 802. The isolation structures 1126 can, for example, provide physical and electrical isolation between the photodetectors 802. The isolation structures 1126 can further be, for example, shallow trench isolation (STI) structures, deep trench isolation (DTI) structures, or other suitable isolation structures.

[0071] According to Fig. 11D is a cross-sectional view 1100D of another example of the integrated chip of Fig. 11C, in which the narrowband filter 102 comprises the embodiments of Fig. 2A. The column structures 110 are thus limited to the defect layer 108.

[0072] Although Fig. 11A to 11D using embodiments of the narrowband filter 102 in Fig. 2A and Fig. 3A, however, in other embodiments, embodiments of the narrowband filter 102 may also be implemented in one of the Fig. 1, 2B to 2E, 3B to 3E, 5A to 5D, 6A and 6B. Furthermore, the Fig. 11A to 11D without absorptive color filters, a low-pass filter and a high-pass filter are illustrated on the narrowband filter 102, however, it is noted that absorptive color filters, a low-pass filter, a high-pass filter or a combination of the above may be located on the narrowband filter 102, as with respect to Fig. 9A, 9B and 10A to 10C are illustrated and described.

[0073] According to Fig. 12 to 15, 16A to 16D, and 17A to 17C, a sequence of cross-sectional views 1200 to 1500, 1600A to 1600D, 1700A to 1700C of various embodiments of a method for forming an integrated BSI image chip including a narrowband high-transmittance filter is provided. Fig. 17A to 17C are alternatives to Fig. 16A to 16D. The procedure is thus based on the illustrative example of Fig. 12 to 15 to Fig. 16A to 16D and in embodiments of the invention of Fig. 12 to 15 to Fig. 17A to 17C. The first embodiments can be carried out, for example, to implement embodiments of the narrowband filter in Fig. 2A to 2E. The second embodiments can be carried out, for example, to form embodiments of the narrowband filter in Fig. 3A to 3E. Although Fig. 12 to 15, 16A to 16D and 17A to 17C are described in relation to a method, however, it is noted that the Fig. 12 to 15, 16A to 16D and 17A to 17C are not limited to the method and can stand alone.

[0074] As shown in the cross-sectional view 1200 of the Fig. 12, photodetectors 802 are formed in a semiconductor substrate 1102. Furthermore, semiconductor devices 1104 and an interconnect structure 1106 are formed on a front side of the semiconductor substrate 1102. The photodetectors 802, the semiconductor substrate 1102, the semiconductor devices 1104, the interconnect structure 1106, or a combination of the above may be formed, for example, as described with respect to Fig. 11A to 11D.

[0075] As also shown by the cross-sectional view 1200 of the Fig. As illustrated in Figure 12, a backside of the semiconductor substrate 1102 is patterned to form isolation trenches 1202 separating the photodetectors 802. The patterning may be performed, for example, by a photolithography / etching process, one or more other suitable patterning processes, or a combination of the above. The photolithography / etching process may, for example, include forming a photoresist mask 1204 having a footprint of the isolation trenches 1202 on the semiconductor substrate 1102, etching into the semiconductor substrate 1102 with the photoresist mask 1204 in place, and removing the photoresist mask 1204.

[0076] As shown in cross-sectional view 1300 of the Fig. 13, an insulating liner 1122 is formed covering the semiconductor substrate 1102 and lining the insulating trenches 1202 (see Fig. 12). In alternative embodiments of the method, the insulating liner 1122 is not formed. The insulating liner 1122 may, for example, be or include silicon oxide and / or one or more other suitable dielectrics. Furthermore, the insulating liner 1122 may be formed, for example, by chemical vapor deposition (CVD), physical vapor deposition (PVD), thermal oxidation, one or more other suitable deposition processes, or a combination of the foregoing.

[0077] As also shown in the cross-sectional view 1300 of the Fig. 13, a first insulating layer 1120a is deposited on the semiconductor substrate 1102 and fills the insulating trenches 1202 (see Fig. 12). The first insulating layer 1120a is dielectric and may, for example, be or comprise an ARC, an organic material, another suitable material, or a combination of the above. The first insulating layer 1120 may be deposited, for example, by CVD, PVD, sputtering, spin-on coating, one or more other suitable deposition processes, or a combination of the above. In some embodiments, the first insulating layer 1120a is self-leveling such that a top or head side of the first insulating layer 1120a levels itself due to gravity. In other embodiments, planarization is performed into the top or head side of the first insulating layer 1120a to level the top or head side. The planarization may, for example, be performed by chemical mechanical polishing (CMP) and / or one or more other suitable planarization processes.

[0078] As shown in cross-sectional view 1400 of the Fig. As illustrated in Figure 14, the first insulating layer 1120a is patterned to define grid trenches 1402 having a grid pattern extending between the photodetectors 802. The patterning may be performed, for example, by a photolithography / etching process, one or more other suitable patterning processes, or a combination of the above. The photolithography / etching process may, for example, include forming a photoresist mask 1404 having a footprint of the grid trenches 1402 on the first insulating layer 1120a, etching into the first insulating layer 1120a with the photoresist mask 1404 in place, and removing the photoresist mask 1404.

[0079] As shown in the cross-sectional view 1500 of the Fig. 15, is shown in the lattice trenches 1402 (see Fig. 14) a metal grid 1124 is formed. The metal grid 1124 blocks the passage of radiation between the photodetectors 802 to reduce crosstalk and improve quantum efficiency. The metal grid 1124 may be or include, for example, copper, aluminum, one or more other suitable metals, or a combination of the above. The metal grid 1124 may be formed, for example, by depositing a metal layer covering the first insulating layer 1120a and filling the grating trenches 1402 and then performing planarization into the metal layer until the first insulating layer 1120a is reached. The deposition may be performed, for example, by CVD, PVD, sputtering, electroplating, electroless deposition, one or more other suitable deposition processes, or a combination of the above.Planarization can be achieved, for example, by CMP and / or one or more other suitable planarization processes.

[0080] As shown in cross-sectional view 1600A of the Fig. As illustrated in Figure 16A, a second insulating layer 1120b is deposited onto the metal grid 1124 and the first insulating layer 1120a. The second insulating layer 1120b is dielectric and may be or include, for example, an ARC, an organic material, another suitable material, or a combination of the foregoing. The second insulating layer 1120b may be deposited, for example, by CVD, PVD, sputtering, spin-on deposition, one or more other suitable deposition processes, or a combination of the foregoing.

[0081] As also shown in cross-sectional view 1600A of the Fig. As illustrated in Figure 16A, a first multilayer film 104 is formed on the second insulating layer 1120b. The first multilayer film 104 alternates from top to bottom between a first refractive index and a second refractive index. In some embodiments, the first multilayer film 104 is or defines a DBR. The first multilayer film 104 includes one or more first layers 202 and one or more second layers 204.

[0082] The one or more first layers 202 are layered alternately with the second layer(s) 204. Each of the one or more first layers 202 has: 1) the first refractive index, 2) the same thickness Tf as any other of the one or more first layers 202, 3) the same material composition as any other of the one or more first layers 202, 4), or a combination of the above. Each of the one or more second layers 204 has: 1) the second refractive index, 2) the same thickness Ts as any other of the one or more second layers 204, 3) the same material composition as any other of the one or more second layers 204, 4), or a combination of the above. The first refractive index may, for example, be about 1.0 to 1.5, and the second refractive index may, for example, be about 1.7 to 4.5, or vice versa.However, other values ​​are also possible. Furthermore, the first refractive index may, for example, be greater than the second refractive index, or vice versa. The first and second layers 202, 204 may, for example, be or comprise materials with low absorption for transmittable wavelengths, transparent materials, dielectric materials, or a combination of the above. In some embodiments, the one or more first layers 202 are or comprise silicon dioxide, whereas the one or more second layers 204 are or comprise titanium oxide, or vice versa. However, other materials are also possible.

[0083] The first multilayer film 104 may be formed, for example, by alternately depositing a first layer 202 and a second layer 204. The deposition may be performed, for example, by CVD, PVD, sputtering, oxidation, one or more other suitable deposition processes, or a combination of the foregoing.

[0084] As also shown in cross-sectional view 1600A of the Fig. 16A, a defect layer 108 is deposited onto the first multilayer film 104. In some embodiments, the defect layer 108 has a different refractive index than the first and second refractive indices of the first multilayer film 104. In some embodiments, a thickness Td of the defect layer 108 differs from the thickness Tf of the one or more first layers 202. In some such embodiments, the defect layer 108 has the first refractive index, is adjacent to one or more second layers 204, has the same material composition as the one or more first layers 202, or a combination of the foregoing. In some embodiments, the thickness Td of the defect layer 108 differs from the thickness Ts of the one or more second layers 204.In some such embodiments, the defect layer 108 has the second refractive index, is adjacent to one or more first layers 202, has the same material composition as the one or more second layers 204, or a combination of the foregoing. In some embodiments, the thickness Td of the defect layer 108 is between about 30 and 600 nanometers. However, other thicknesses for the defect layer 108 are also contemplated. In some embodiments, the defect layer 108 is or comprises silicon oxide, titanium oxide, one or more other suitable materials, or a combination of the foregoing. The defect layer 108 may be formed, for example, by CVD, PVD, sputtering, oxidation, one or more other suitable deposition processes, or a combination of the foregoing.

[0085] As shown by cross-sectional view 1600B of the Fig. 16B, the defect layer 108 is patterned to form a plurality of columnar cavities 602 arranged in one or more periodic patterns. For clarity, only some of the columnar cavities 602 are labeled 602. As will be seen below, the high-transmission band of the narrowband filter that is formed shifts based on the fill factor of the columnar cavities 602. In some embodiments, the fill factor of the columnar cavities 602 varies between regions of the defect layer 108. For example, the columnar cavities 602 may have a first fill factor in a first region 108a of the defect layer 108 overlying one of the photodetectors 802 and a second, different fill factor in a second region 108b of the defect layer 108 overlying another of the photodetectors 802.The head-side plan view of the columnar structures 110 in each region of the defect layer 108 may be, for example, as shown in one of the . Fig. 7A to 7G illustrated.

[0086] The patterning may be performed, for example, by a photolithography / etching process, a drilling process, one or more other suitable patterning processes, or a combination of the above. The photolithography / etching process may, for example, include forming a photoresist mask 1602 having a footprint of the columnar cavities 602 on the defect layer 108, etching into the defect layer 108 with the photoresist mask 1602 in place, and removing the photoresist mask 1602. The photoresist mask 1602 may, for example, be formed with a single photomask or photostamp and may be used to form the columnar cavities 602 with fill factors varying between multiple different regions of the defect layer 108.

[0087] As shown in cross-sectional view 1600C of the Fig. 16C, in the columnar cavities 602 (see Fig. 16B) Pillar structures 110 are formed. For clarity, only some of the pillar structures 110 are labeled 110. In alternative embodiments, the pillar structures 110 are not formed, and the columnar cavities 602 remain unfilled until completion of the process. The pillar structures 110 have refractive indices that are different (e.g., lower or higher) than those of the defect layer 108 and the first and second layers 202, 204. In some embodiments, each of the pillar structures 110 has a refractive index that is the same as any other of the pillar structures 110 and / or has the same material composition as any other of the pillar structures 110. The pillar structures 110 may be or include, for example, materials with low absorption for transmittable wavelengths, transparent materials, dielectric materials, or a combination of the foregoing.The pillar structures 110 can be formed, for example, by depositing a layer covering the defect layer 108 and filling the columnar cavities 602, and then performing planarization into the layer until the defect layer 108 is reached. The deposition can be performed, for example, by CVD, PVD, sputtering, one or more other suitable deposition processes, or a combination of the above. The planarization can be performed, for example, by CMP and / or one or more other suitable planarization processes.

[0088] As shown in cross-sectional view 1600D of the Fig. As illustrated in Figure 16D, a second multilayer film 106 is formed on the defect layer 108 and the pillar structures 110. The second multilayer film 106 alternates, from top to bottom, between the first refractive index of the first multilayer film 104 and the second refractive index of the first multilayer film 104. In some embodiments, the second multilayer film 106 is or defines a DBR. The second multilayer film 106 includes one or more third layers 206 and one or more fourth layers 208.

[0089] The one or more third layers 206 are layered alternately with the fourth layer(s) 208. Each of the one or more third layers 206 has: 1) the first refractive index, 2) the same thickness Tf as any other of the one or more first and / or third layers 206, 3) the same material composition as any other of the one or more first and / or third layers 202, 206, 4), or a combination of the above. Each of the one or more fourth layers 208 has: 1) the second refractive index, 2) the same thickness Ts as any other of the one or more second and / or fourth layers 204, 208, 3) the same material composition as any other of the one or more second and / or fourth layers 204, 208, 4), or a combination of the above.The third and fourth layers 206, 208 may, for example, be or comprise materials with low absorption for transmittable wavelengths, clear materials, dielectric materials, or a combination of the foregoing. In some embodiments, the one or more third layers 206 are or comprise silicon dioxide, whereas the one or more fourth layers 208 are or comprise titanium oxide, or vice versa. However, other materials are also contemplated.

[0090] The second multilayer film 106 may be formed, for example, by alternately depositing a third layer 206 and the fourth layer 208. The deposition may be performed, for example, by CVD, PVD, sputtering, oxidation, one or more other suitable deposition processes, or a combination of the foregoing.

[0091] Together, the first and second multilayer films 104, 106, the defect layer 108, and the pillar structures 110 define the narrowband filter 102. The first and second multilayer films 104, 106 define a low-transmittance band (i.e., a wavelength range) in which the transmittance is low. The defect layer 108 defines a high-transmittance band (i.e., a wavelength range) in which the transmittance is high. The high-transmittance band is narrow and divides the low-transmittance band into segments between an upper and a lower limit of the low-transmittance band. The pillar structures 110 shift the position of the high-transmittance band based on the refractive index of the pillar structures 110 and a fill factor of the pillar structures 110.The fill factor can be varied, for example, by changing the size of the pillar structures 110, the spacing between the pillar structures 110, the shape of the pillar structure 110, another property of the pillar structures 110, or a combination of the above. If the pillar structures 110 have a refractive index lower than the refractive indices of the first and second multilayer films 104, 106, then increasing the fill factor shifts the high-transmittance band toward lower wavelengths, and decreasing the fill factor shifts the high-transmittance band toward higher wavelengths.If the pillar structures 110 have a refractive index that is greater than the refractive indices of the first and second multilayer films 104, 106, then increasing the fill factor shifts the high-transmittance band toward higher wavelengths and decreasing the fill factor shifts the high-transmittance band toward lower wavelengths.

[0092] Due to the pillar structures 110, the position of the high-transmittance band is highly controllable. Furthermore, due to the use of the defect layer 108 to create the high-transmittance band, the high-transmittance band can be narrow. Furthermore, since the first and second multilayer films 104, 106 can be formed with transparent materials and / or with materials with low absorption for wavelengths transmitted by the narrowband filter 102, high transmittances can be achieved at the high-transmittance band.

[0093] By varying the fill factor of the column structures 110 in different regions of the narrowband filter 102, the position of the high-transmittance band in the different regions can be varied. For example, a first region 102a of the narrowband filter 102 can have a low or zero fill factor and a second region 102b of the narrowband filter 102 can have a comparatively high fill factor, whereby the high-transmittance band can differ between the first and second regions 102a, 102b. Furthermore, as with respect to Fig. 16B, the fill factor, and thus the high-transmittance bands, can be controlled in different regions using a single photomask or photostamp, thus keeping costs low. For example, the narrowband filter 102 can be formed using a single photomask or photostamp to selectively transmit red, green, or blue radiation wavelengths in different regions of the narrowband filter.

[0094] The above embodiments of the method were based on the Fig. 12 to 15 to the Fig. 16A to 16D. However, according to the invention, instead of the measures in Fig. 16A to 16D the measures in Fig. 17A to 17C, so that the procedure of Fig. 12 to 15 to Fig. 17A to 17C.

[0095] As shown in cross-sectional view 1700A of the Fig. 17A, the second insulating layer 1120b, the first multilayer film 104, the defect layer 108, and the second multilayer film 106 are formed stacked on the second insulating structure 1120a and the metal grid 1124. The second insulating layer 1120b, the first multilayer film 104, and the defect layer 108 may be formed, for example, as with respect to Fig. 16A, and the second multilayer film 106 may be formed, for example, as described with respect to Fig. 16D described.

[0096] As shown by cross-sectional view 1700B of the Fig. 17B, ​​the first and second multilayer films 104, 106 and the defect layer 108 are patterned to form a plurality of columnar cavities 602 in one or more periodic patterns. For clarity, only some of the columnar cavities 602 are labeled 602. The patterning may be performed, for example, as described with respect to Fig. 16B. For example, patterning may be performed by a photolithography / etching process using a single photomask or photostencil to form the columnar cavities 602 with fill factors varying between several different regions of the defect layer 108.

[0097] As shown in cross-sectional view 1700C of the Fig. 17C, in the columnar cavities 602 (see Fig. 17B) Column structures 110 are formed. For clarity, only some of the column structures 110 are labeled 110. In alternative embodiments, the column structures 110 are not formed and the column-like cavities 602 remain unfilled until completion of the process. The column structures 110 can, for example, be formed as with respect to Fig. 16C described.

[0098] According to Fig. 18 is a block diagram 1800 of some embodiments of the method of Fig. 12 to 15, 16A to 16D and 17A to 17C.

[0099] In 1802, photodetectors are formed in a semiconductor substrate. Furthermore, semiconductor devices and an interconnection structure are formed on a front side of the semiconductor substrate. See, for example, Fig. 12.

[0100] In 1804, a backside of the semiconductor substrate is patterned to form trenches separating the photodetectors. See, for example, Fig. 12.

[0101] In 1806, the trenches were filled with a first insulating layer. See, for example, Fig. 13.

[0102] In 1808, a metal grid embedded in the first insulating layer was formed. See, for example, Fig. 14 and Fig. 15.

[0103] In 1810, a second insulating layer was formed over the metal grid and the first insulating layer. See, for example, Fig. 16A or Fig. 17A.

[0104] In 1812, a first multilayer film is formed on the second insulating layer, alternating from top to bottom between a first refractive index and a second refractive index. See, for example, Fig. 16A or Fig. 17A. In alternative embodiments, the steps in 1804 to 1810 are omitted and the first multilayer film is instead formed on the interconnect structure.

[0105] In 1814, a defect layer was formed on the first multilayer film. See, for example, Fig. 16A or Fig. 17A.

[0106] In some first embodiments of the method, the method proceeds from 1814 to 1816a to 1816c. In 1816a, the defect layer is patterned to form columnar cavities in the defect layer. See, for example, Fig. 16B. In 1816b, columnar structures are formed in the columnar cavities. See, for example, Fig. 16C. In 1816c, a second multilayer film is formed on the defect layer, alternating from top to bottom between the first refractive index and the second refractive index. See, for example, Fig. 16D.

[0107] In some second embodiments of the method, the method proceeds from 1814 to 1818a to 1818c. In 1818a, a second multilayer film is formed on the defect layer, alternating from top to bottom between the first refractive index and the second refractive index. See, for example, Fig. 17A. In 1818b, the defect layer and the first and second multilayer films are patterned to form columnar cavities. See, for example, Fig. 17B. In 1818c, columnar structures are formed in the columnar cavities. See, for example, Fig. 17C.

[0108] Although the block diagram 1800 of the Fig. 18 are illustrated and described herein as a sequence of acts or events, however, it is noted that the illustrated order of such acts or events is not to be interpreted as limiting. For example, some acts may occur in different orders and / or concurrently with other acts or events than those illustrated and / or described herein. Further, not all illustrated acts are required to implement one or more aspects or embodiments of the present description, and one or more of the acts recited herein may be performed in one or more separate acts and / or phases.

[0109] According to Fig. 19, Fig. 20, Fig. 21A and Fig. 21B shows a sequence of cross-sectional views 1900, 2000, 2100A, and 2100B of various embodiments of a method for forming an integrated FSI image chip including a narrowband high-transmittance filter. Fig. 21B is an alternative to Fig. 21A. The method thus proceeds in first embodiments of Fig. 19 and Fig. 20 to Fig. 21A and in second embodiments of Fig. 19 and Fig. 20 to Fig. 21B. The first embodiments can be carried out, for example, to implement embodiments of the narrowband filter in Fig. 2A to 2E. The second embodiments can be carried out, for example, to form embodiments of the narrowband filter in Fig. 3A to 3E. Although Fig. 19, Fig. 20, Fig. 21A and Fig. 21B in relation to a method, however, it is noted that the Fig. 19, Fig. 20, Fig. 21A and Fig. The structures shown in Figure 21B are not limited to the method and can stand alone.

[0110] As shown by the cross-sectional view 1900 of the Fig. 19, photodetectors 802 are formed in a semiconductor substrate 1102, and insulating structures 1126 extending into a front side of the semiconductor substrate 1102 and separating the photodetectors 802 are formed. Furthermore, semiconductor devices 1104 are formed on the front side of the semiconductor substrate 1102. The photodetectors 802, the semiconductor substrate 1102, the semiconductor devices 1104, the insulating structures 1126, or a combination of the above may be formed, for example, as described with respect to Fig. 11A to 11D.

[0111] As shown by the cross-sectional view 2000 of the Fig. 20, an interconnection structure 1106 is formed on the front side of the semiconductor substrate 1102, covering the photodetectors 802, the semiconductor substrate 1102, the semiconductor devices 1104, and the isolation structures 1126. The interconnection structure 1106 may, for example, be formed as described with respect to Fig. 11A to 11D and / or may be carried out, for example, by a sequence of single and / or dual damascene processes.

[0112] As shown in cross-sectional view 2100A of the Fig. 21A, a narrowband filter 102 is formed covering the interconnection structure 1106 on the front side of the semiconductor substrate 1102. The narrowband filter 102 includes a first multilayer film 104, a defect layer 108, pillar structures 110, and a second multilayer film 106. The defect layer 108 is located on the first multilayer film 104, and the second multilayer film 106 is located on the defect layer 108. Furthermore, the pillar structures 110 extend through the defect layer 108 and are confined to the defect layer 108. The narrowband filter 102 can be formed, for example, as described with respect to Fig. 16A to 16D.

[0113] The above examples of the procedure were based on the Fig. 19 and Fig. 20 to Fig. 21A. However, in embodiments according to the invention, instead of the measures in Fig. 21A the measures in Fig. 21B, so that the procedure of Fig. 19 and Fig. 20 to Fig. 21B.

[0114] As shown in cross-sectional view 2100B of the Fig. 21B, the pillar structures 110 are formed such that they extend through the defect layer 108 and the first and second multilayer films 104, 106 instead of only through the defect layer 108. The narrowband filter 102 may, for example, be formed as with respect to Fig. 17A to 16C.

[0115] According to Fig. 22 is a block diagram 2200 of some embodiments of the method of Fig. 19, Fig. 20, Fig. 21A and Fig. 22B.

[0116] In 2202, photodetectors are formed in the semiconductor substrate. Furthermore, semiconductor devices and an interconnection structure are formed on a front side of the semiconductor substrate. See, for example, Fig. 19 and Fig. 20.

[0117] In 2204, a first multilayer film is formed on the interconnect structure, alternating from top to bottom between a first refractive index and a second refractive index. See, for example, Fig. 21A or Fig. 21B.

[0118] In 2206, a defect layer is formed on the first multilayer film. See, for example, Fig. 21A or Fig. 21B.

[0119] In some first embodiments of the method, the method proceeds from 2206 to 2208a to 2208c. In 2208a, the defect layer is patterned to form columnar cavities in the defect layer. See, for example, Fig. 21A. In 2208b, columnar structures are formed in the columnar cavities. See, for example, Fig. 21A. In 2208c, a second multilayer film is formed on the defect layer, alternating from top to bottom between the first refractive index and the second refractive index. See, for example, Fig. 21A.

[0120] In some second embodiments of the method, the method proceeds from 2206 to 2210a to 2210C. In 2210a, a second multilayer film is formed on the defect layer, alternating from top to bottom between the first refractive index and the second refractive index. See, for example, Fig. 21B. In 2210b, the defect layer and the first and second multilayer films are patterned to form columnar cavities. See, for example, Fig. 21B. In 2210C, columnar structures are formed in the columnar cavities. See, for example, Fig. 21B.

[0121] Although the block diagram 2200 of the Fig.22 are illustrated and described herein as a sequence of acts or events, however, it is noted that the illustrated order of such acts or events is not to be interpreted as limiting. For example, some acts may occur in different orders and / or concurrently with other acts or events than those illustrated and / or described herein. Further, not all illustrated acts are required to implement one or more aspects or embodiments of the present description, and one or more of the acts recited herein may be performed in one or more separate acts and / or phases.

Claims

[1] Image sensor comprising: a substrate (1102), a photodetector (802) in the substrate (1102), and a filter (102) disposed over the photodetector (802) and comprising: a first Bragg mirror, DBR (104), a second DBR (106), a defect layer (108) between the first (104) and the second (106) DBR and a plurality of pillar structures (110) extending through the first and second DBRs (104, 106) and the defect layer (108), the pillar structures (110) being in a periodic pattern and having a refractive index that differs from a refractive index of the defect layer (108). [2] The image sensor of claim 1, wherein the first or second DBR (104, 106) comprises a plurality of first layers and a plurality of second layers, the second layers being layered alternately with the first layers, and the defect layer (108) having a refractive index different from refractive indices of the first and second layers, respectively. [3] The image sensor of claim 1, wherein the first and second DBRs (106) each comprise a plurality of first layers and a plurality of second layers, the second layers being layered alternately with the first layers, the defect layer (108) and the first layers having the same refractive index, the defect layer (108) directly contacting one of the second layers of the first DBR (104) and one of the second layers of the second DBR (106), and the defect layer (108) having a different thickness than any one of the first layers. [4] Image sensor according to one of the preceding claims, wherein the column structures (110) comprise a column structure (110) with a head-side plan having a circular or square shape. [5] The image sensor according to any one of claims 1 to 4, wherein the column structures (110) are arranged in a plurality of rows and a plurality of columns. [6] Image sensor according to one of claims 1 to 4, wherein the column structures (110) are arranged in quincunx patterns. [7] Image sensor according to one of claims 1 to 6, further comprising: an absorptive color filter (902) located above the first and second DBR (104, 106). [8] Image sensor according to one of the preceding claims, further comprising: a low-pass or high-pass filter (1004) located above the first and second DBR (104, 106). [9] A method of forming an image sensor, the method comprising: Forming a photodetector (802) in a substrate (1102), Depositing a first multilayer film onto the substrate (1102), the first multilayer film (104) comprising a plurality of first layers and a plurality of second layers, the first layers being layered alternately with the second layers and having a same first refractive index that differs from a second refractive index common to the second layers, Depositing a defect layer (108) on the first multilayer film (104), Depositing a second multilayer film (106) on the defect layer (108), wherein the second multilayer film (106) comprises a plurality of third layers and a plurality of fourth layers, wherein the third layers are layered alternately with the fourth layers and each have the first refractive index, and wherein the fourth layers each have the second refractive index, and Etching into the first and second multilayer films (104, 106) and etching into the defect layer (108) to form the plurality of columnar cavities (602), wherein the columnar cavities (602) are in a periodic pattern. [10] The method of claim 9, further comprising: Forming a plurality of columnar structures (110) in the columnar cavities (602), wherein the columnar structures are formed with a refractive index that differs from a refractive index of the defect layer (108). [11] The method of claim 10, wherein the refractive index of the defect layer (108) differs from the first and second refractive indices, and wherein the first and second refractive indices are between the refractive index of the column structures (110) and the refractive index of the defect layer (108). [12] The method of claim 9, wherein the defect layer (108) comprises the same material and the same refractive index as the first layers, a single one of the second layers is directly contacted, and has a different thickness than the respective thicknesses of the first layers. [13] A method according to any one of claims 9 to 12, further comprising: Forming a back end of line (BEOL) interconnect structure over the photodetector (802) and the substrate (1102), wherein the first multilayer film (104) is deposited over the BEOL interconnect structure. [14] A method according to any one of claims 9 to 12, further comprising: Forming a back end of line (BEOL) interconnect structure on a first side of the substrate (1102), wherein the first multilayer film (104) is deposited on a second side of the substrate (1102), the first and second sides being opposite each other. [15] Integrated chip comprising: a substrate (1102), a plurality of photodetectors (802) in the substrate (1102), wherein the plurality of photodetectors (802) comprises a first photodetector (802) and a second photodetector (802), a pair of multilayer films (104, 106) each comprising a plurality of first layers and a plurality of second layers, the first layers being layered alternately with the second layers and having a different refractive index than the second layers, a defect layer (108) directly between the multilayer films (104, 106), wherein the defect layer (108) has a different thickness or refractive index than the first and second layers, a first group of column structures (110) lying above the first photodetector (802) and extending through the defect layer (108), and a second group of pillar structures (110) overlying the second photodetector (802) and extending through the defect layer (108), wherein the pillar structures of the second group have a different fill factor than the pillar structures (110) of the first group, wherein the first and second groups of pillar structures (110) extend through the multilayer films (104, 106) and the defect layer (108).

Images