Optical device

Abstract

To provide an optical device capable of reducing a focal distance of light and realizing the optical device smaller in thickness.SOLUTION: An optical device 100 comprises a photoelectric conversion layer 110, a reflection prevention layer 170, a ground layer 130, a lower part meta layer BML, and an upper part meta layer TML. The photoelectric conversion layer includes a plurality of photodiodes 112. The reflection prevention layer is arranged on the photoelectric conversion layer. The ground layer is arranged on the reflection prevention layer. The lower part meta layer is arranged on the ground layer, and includes a plurality of lower part meta units 141 and 142 and a filling material F1 between the lower part meta units. The filling material is continuously extended from the ground layer, and a material of the filling material is the same as a material of the ground layer. The upper part meta layer is arranged above the lower part meta layer, and includes a plurality of upper part meta units 152b and 152c1, and a plurality of air recesses 154. The respective air recesses are arranged between two adjacent upper part meta units. The optical device further includes an internal space layer S arranged between the upper part meta layer and the lower part meta unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to optical devices, and more particularly, to optical devices having multilayer metasurfaces. [Background technology]

[0002] With the development of semiconductor devices, there is a strong demand for miniaturization technology for complementary metal-oxide semiconductor (CMOS) image sensors (also known as CIS). In CIS, the arrangement and dimensions of elements within the optical device affect the focal length of light, which in turn affects the thickness of the elements. Furthermore, different regions of light are suitable for different types of optical devices. Therefore, optical devices with thinner thicknesses are needed to shorten the focal length of light. Summary of the Invention

[0003] One aspect of the present disclosure provides an optical device. The optical device includes a photoelectric conversion layer, an anti-reflection layer, an underlayer, a lower meta layer, and an upper meta layer. The photoelectric conversion layer includes a plurality of photodiodes. The anti-reflection layer is disposed on the photoelectric conversion layer. The underlayer is disposed on the anti-reflection layer. The lower meta layer is disposed on the underlayer and includes a plurality of lower meta units and a filler between the lower meta units, the filler extending continuously from the underlayer, and the filler material is the same as the material of the underlayer. The upper meta layer is disposed above the lower meta layer and includes a plurality of upper meta units and a plurality of air recesses, where each of the plurality of air recesses is disposed between two adjacent upper meta units.

[0004] In some embodiments, the height of the underlayer from the bottom surface of the lower meta unit to the top surface of the antireflective layer is based on the following formula:

number

[0005] In some embodiments, the optical device further includes a color filter layer disposed between the anti-reflection layer and the underlayer, the color filter layer including a plurality of color filters, each corresponding to one or two photodiodes, and the height of the underlayer is from the bottom surface of the lower meta unit to the top surface of the color filter layer.

[0006] In some embodiments, the color filter layer includes a first color filter, a second color filter, and a third color filter, and the plurality of lower meta units are disposed above the first color filter and the second color filter, but not above the third color filter.

[0007] In some embodiments, the effective refractive index of the upper metalayer is in the range of 1.3 to 1.6, the refractive index of the lower metaunit is in the range of 1.4 to 2.6, and the refractive index of the underlayer is in the range of 1.2 to 1.8, and the refractive index of the lower metaunit is greater than the refractive index of the underlayer.

[0008] In some embodiments, the upper meta layer of the optical device further includes a capping layer conformally and continuously lining the plurality of upper meta units and the plurality of air recesses, leaving the plurality of air recesses in the upper meta layer.

[0009] In some embodiments, the refractive index of the upper metaunit is in the range of 1.4 to 2.6 and the refractive index of the capping layer is in the range of 1.4 to 1.6, and the refractive index of the upper metaunit is different from the refractive index of the capping layer.

[0010] In some embodiments, the upper metalayer has a global shift relative to the lower metalayer.

[0011] In some embodiments, the top meta unit of the top meta layer has an internal shift, the internal shift including a negative shift and a positive shift.

[0012] In some embodiments, the optical device further includes an intermediate meta layer disposed between the upper meta layer and the lower meta layer, the intermediate meta layer including a plurality of intermediate meta units disposed in a first layer and a second layer, the first layer connected to the upper meta unit and the second layer connected to the lower meta layer, and the first layer and the second layer separated by the underlayer.

[0013] In some embodiments, the optical device further includes a color filter layer and an internal space layer, the color filter layer being disposed between the photoelectric conversion layer and the underlayer, and the internal space layer being disposed continuously between the plurality of lower meta units and the plurality of upper meta units.

[0014] In some embodiments, the color filter layer includes a plurality of color filters, each corresponding to four photodiodes, and the height of the underlayer from the bottom surface of the lower meta unit to the top surface of the color filter layer is based on the following formula:

number

[0015] In some embodiments, the color filter layer includes a first color filter, a second color filter, and a third color filter, the plurality of lower meta units are disposed above the first color filter, the second color filter, and the third color filter, and the plurality of upper meta units are disposed above the first color filter and the second color filter, but not above the third color filter.

[0016] In some embodiments, the color filter layer comprises a first color filter and a second color filter, and the first color filter under The photodiodes extend along a first direction and are arranged along a second direction substantially perpendicular to the first direction. under The photodiodes on one side extend along the second direction and are arranged along the first direction.

[0017] In some embodiments, the axis of symmetry of each of the lower metaunits is offset from the axis of symmetry of each of the upper metaunits.

[0018] In some embodiments, the lower meta units are arranged in one layer, and the lower meta units connect to the upper meta units.

[0019] In some embodiments, the refractive index of the lower metaunit is in the range of 1.4 to 2.6, the refractive index of the upper metaunit is in the range of 1.4 to 2.6, and the refractive index of the lower metaunit is the same as the refractive index of the upper metaunit.

[0020] In some embodiments, the refractive index of the interior space layer is the same as the refractive index of the lower metaunit or the refractive index of the upper metaunit.

[0021] In some embodiments, the refractive index of the interior space layer is different from the refractive index of the lower metaunit and the refractive index of the upper metaunit.

[0022] In some embodiments, the width of each of the lower metaunits is in the range of 70 nm to 500 nm, the width of each of the upper metaunits is in the range of 70 nm to 500 nm, the height of each of the lower metaunits is in the range of 50 nm to 500 nm, the height of each of the upper metaunits is in the range of 50 nm to 500 nm, and the height of the internal space layer is in the range of 0 to 500 nm. [Brief explanation of the drawings]

[0023] Aspects of the present disclosure may be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard industry practice, the various features have not been drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of illustration. [Figure 1] 1 is a cross-sectional view of an optical device according to an embodiment of the present disclosure. [Figure 2] 2 is another cross-sectional view of the optical device of FIG. 1. [Figure 3] FIG. 3 is a top view of the color filter layer and upper meta layer of the optical device of FIGS. 1 and 2. [Figure 4] 3 is a top view of the color filter layer and lower meta unit of the optical device of FIGS. 1 and 2. FIG. [Figure 5]2 is a cross-sectional view of an optical device according to another embodiment of the optical device of FIG. 1. FIG. [Figure 6] 1 is a cross-sectional view of an optical device according to an embodiment of the present disclosure. [Figure 7] 7 is a top view of the color filter layer and upper meta unit of the optical device of FIG. 6. [Figure 8] 7 is a top view of the color filter layer and lower meta unit of the optical device of FIG. 6. [Figure 9] 1 is a cross-sectional view of an optical device according to an embodiment of the present disclosure. [Figure 10] 10 is a top view of the color filter layer and lower meta unit of the optical device of FIG. 9. [Figure 11] 1 is a cross-sectional view of an optical device according to an embodiment of the present disclosure. [Figure 12] 12 is a top view of the color filter layer and upper meta unit of the optical device of FIG. 11. [Figure 13] 12 is a top view of the color filter layer and lower meta unit of the optical device of FIG. 11. [Figure 14A] 1 is a cross-sectional view of an optical device according to an embodiment of the present disclosure. [Figure 14B] 14B is a top view of a color filter layer and an upper meta unit according to another embodiment of the optical device of FIG. 14A. [Figure 15] 1 is a cross-sectional view of an optical device according to an embodiment of the present disclosure. [Figure 16] 16 is a top view of the color filter layer of the optical device of FIG. 15. [Figure 17A] 1 is a cross-sectional view of an optical device according to some embodiments of the present disclosure. [Figure 17B] 1 is a cross-sectional view of an optical device according to some embodiments of the present disclosure. [Figure 17C] FIG. 17C is a top view of the color filter layer of the optical device of FIGS. 17A and 17B. [Figure 18A] 1 is a cross-sectional view of an optical device according to some embodiments of the present disclosure. [Figure 18B] 1 is a cross-sectional view of an optical device according to some embodiments of the present disclosure. [Figure 18C] FIG. 18C is a top view of the color filter layer of the optical device of FIGS. 18A and 18B. [Figure 19] 1 is a cross-sectional view of an optical device according to some embodiments of the present disclosure. [Figure 20] 1 is a cross-sectional view of an optical device according to some embodiments of the present disclosure. [Figure 21] 1 is a cross-sectional view of an optical device according to some embodiments of the present disclosure. [Figure 22A] 7A-7D are cross-sectional views of various stages in the manufacture of the optical device of FIG. 6. [Figure 22B] 7A-7D are cross-sectional views of various stages in the manufacture of the optical device of FIG. 6. [Figure 22C] 7A-7D are cross-sectional views of various stages in the manufacture of the optical device of FIG. 6. [Figure 22D] 7A-7D are cross-sectional views of various stages in the manufacture of the optical device of FIG. 6. [Figure 22E] 7A-7D are cross-sectional views of various stages in the manufacture of the optical device of FIG. 6. [Figure 22F] 7A-7D are cross-sectional views of various stages in the manufacture of the optical device of FIG. 6. [Figure 22G] 7A-7D are cross-sectional views of various stages in the manufacture of the optical device of FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first structure above or on a second structure in the following description may include embodiments in which the first and second structures are formed in direct contact, or may include embodiments in which an additional structure may be formed between the first and second structures such that the first and second structures are not in direct contact. Furthermore, the disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purposes of simplicity and clarity and does not, in itself, indicate a relationship between the various embodiments and / or structures described.

[0025] Although terms such as "first," "second," etc. are used herein to describe various elements, it should be understood that these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element, without departing from the scope of the embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0026] Additionally, spatially relative terms such as "bottom," "lower," "bottom," "upper," "top," and the like, are intended to describe the relationship of one element or feature to another, as shown in the figures, and may be used herein for ease of description. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be oriented in other directions (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted similarly.

[0027] In the field of CIS, the arrangement and dimensions of elements within the optical device affect the focal length of light, which in turn affects the thickness and performance of the optical device. The present disclosure provides a multilayer metasurface with a hybrid dielectric environment stacked on a CIS to shorten the focal length of light. The disclosed optical device can shorten the focal length of light by adjusting the phase difference. This phase difference is adjusted by different materials with different refractive indices. After light passes through different materials with different refractive indices (the hybrid dielectric environment), the light's energy tends to concentrate over a shorter distance. Therefore, the focal length of light can be shortened. As a result, the thickness of the underlying layers of the disclosed optical device can be reduced, thereby reducing the overall dimensions of the optical device and improving the performance of the optical device.

[0028] FIG. 1 is a cross-sectional view of an optical device 100 according to one embodiment of the present disclosure. The optical device 100 includes a photoelectric conversion layer 110, a color filter layer 120, an underlayer 130, a lower meta layer (BML), an upper meta layer (TML), and an anti-reflection layer 170. The photoelectric conversion layer 110 includes a plurality of photodiodes 112 and a plurality of deep trench isolations (DTIs) 114. The DTIs 114 separate the photodiodes 112 from one another. The anti-reflection layer 170 is disposed on the photoelectric conversion layer 110. The color filter layer 120 is disposed on the anti-reflection layer 170. The underlayer 130 is disposed on the color filter layer 120. The lower meta layer (BML) includes a plurality of lower meta units 140 and a filler F1 between the lower meta units 140. The filler F1 extends continuously from the underlayer 130, as shown in FIG. 1 . The material of the filler F1 is the same as the material of the underlayer 130. The upper meta layer TML is disposed above the lower meta layer BML. The upper meta layer TML includes a plurality of upper meta units 152 and a plurality of air recesses 154, each of which is disposed between two adjacent upper meta units 152.

[0029] In some embodiments, the effective refractive index of the upper metalayer TML is less than the refractive index of the lower metaunits 140. In some embodiments, the refractive index of the lower metaunits 140 is greater than the refractive index of the underlayer 130. In some embodiments, the refractive index of the upper metaunits 152 is in the range of 1.4 to 1.7, such as 1.45, 1.5, 1.55, 1.6, or 1.65. In some embodiments, the effective refractive index of the upper metalayer TML is in the range of 1.3 to 1.6, such as 1.35, 1.4, 1.45, 1.5, or 1.55. It should be understood that the effective refractive index herein is an average value calculated from the refractive index of the upper metaunits 152 and the refractive index of the air recesses 154. In some embodiments, the refractive index of the lower metaunits 140 is in the range of 1.4 to 2.6, such as 1.8, 2, 2.2, or 2.4. In some embodiments, the refractive index of the underlayer 130 is in the range of 1.2 to 1.8, such as 1.3, 1.4, 1.5, 1.6, or 1.7.

[0030] 1, the color filter layer 120 is disposed between the anti-reflection layer 170 and the underlayer 130. The pixel dimension p is determined by the distance between two adjacent DTIs 114. The pixel dimension p can be understood as the pixel length or pixel width. The height h of the underlayer 130 from the bottom surface 140s of the lower meta unit 140 to the top surface 120s of the color filter layer 120 is based on the following equation:

number

[0031] FIG. 2 is another cross-sectional view of the optical device 100 of FIG. 1. FIG. 3 is a top view of the color filter layer 120 and upper meta layer TML of the optical device 100 of FIGS. 1 and 2. FIG. 4 is a top view of the color filter layer 120 and lower meta unit 140 of the optical device 100 of FIGS. 1 and 2. Specifically, FIG. 3 is a top view of the upper meta layer TML of the optical device 100 in a cross section taken along line A-A' in FIG. 1, with the color filter layer 120 shown for clarity. FIG. 4 is a top view of the lower meta unit 140 of the optical device 100 in a cross section taken along line B-B' in FIG. 1 and line C-C' in FIG. 2, with the color filter layer 120 shown for clarity.

[0032] As shown in FIGS. 1-3, upper meta unit 152 includes upper meta units 152b, 152c1, and 152c4. Upper meta units 152b, 152c1, and 152c4 are arranged along the X and Y directions and extend along the Z direction. The "b" in upper meta unit 152b herein may be understood to refer to an upper meta unit located above the boundary of a color filter (such as color filters 121-124 shown in FIG. 3). Here, the "c" in upper meta units 152c1 and 152c4 refers to an upper meta unit located above the center of a color filter (such as color filters 121-124 shown in FIG. 3). The number following "152c" corresponds to the last number of color filters 121-124. For example, as shown in FIG. 3, upper meta unit 152c1 corresponds to color filter 121, and upper meta unit 152c4 corresponds to color filter 124. 1, 2, and 4, lower meta unit 140 includes lower meta units 141, 142, and 144, and the numbers after "14" in lower meta units 141, 142, and 144 correspond to the last numbers of color filters 121, 122, and 124. Lower meta units 141, 142, and 144 are arranged along the X and Y directions and extend along the Z direction.

[0033] See FIGS. 1 and 3. Color filter layer 120 includes multiple color filters, such as color filters 121-124. Each of color filters 121-124 is separated by separation grid 125. Each separation grid includes metal grid 126, and the material of metal grid 126 may include an absorbing material or a metal, such as W, TiN, Cu, or Al. Color filters 121-124 are different from each other. In some embodiments, color filter 121 is the same as color filter 124. In some embodiments, each of color filters 121-124 may be a green, red, blue, white, yellow, cyan, magenta, or other pixel. In some embodiments, color filters 121 and 124 are green pixels, color filter 122 is a red pixel, and color filter 123 is a blue pixel.

[0034] 1 and 2, each color filter (color filters 121-124) corresponds to one photodiode 112. As shown in FIGS. 1-3, upper meta unit 152c1 corresponds to the center of color filter 121, upper meta unit 152c4 corresponds to the center of color filter 124, and upper meta unit 152b corresponds to the boundary of color filters 121-124. In some embodiments, some of the upper meta units (e.g., upper meta units 152c1, 152c4, 152b) are positioned above color filters 121, 122, and 124, but not above color filter 123, as shown in FIG.

[0035] As shown in Figures 1 and 4, lower meta unit 141 corresponds to the center of color filter 121, and lower meta unit 142 corresponds to the center of color filter 122. As shown in Figures 2 and 4, lower meta unit 144 corresponds to the center of color filter 124. The number and size of upper meta units 152 and lower meta units 140 can be adjusted to achieve a reduced height h of underlayer 130. In some embodiments, some of the lower meta units (such as lower meta units 141, 142, and 144) are positioned above color filters 121, 122, and 124, but not above color filter 123, as shown in Figure 4.

[0036] Referring again to FIG. 1 , in some embodiments, optical device 100 further includes an internal space layer S disposed between upper metalayer TML and lower metaunit 140. In some embodiments, the refractive index of internal space layer S is the same as the refractive index of lower metaunit 140. In some embodiments, depending on the manufacturing process of optical device 100, the refractive index of internal space layer S is different from the refractive index of lower metaunit 140. In some embodiments, depending on the manufacturing process of optical device 100, internal space layer S may not be present in optical device 100.

[0037] FIG. 5 is a cross-sectional view of an optical device 100a according to another embodiment of the optical device 100 of FIG. 1. The upper metalayer TML of the optical device 100a further includes a capping layer 510. The capping layer 510 conformally and continuously lines the upper meta units 152 (including upper meta units 152c1, 152c4, and 152b) and the air recesses 154, with the air recesses 154 being disposed between two adjacent upper meta units 152. Specifically, the upper meta unit 152c1 is disposed between two adjacent upper meta units 152b. In other words, the air recesses 154 are left in the upper meta layer. The capping layer 510 is configured to protect the upper meta units 152. In some embodiments, the refractive index of the capping layer 510 is in the range of 1.4 to 1.6, such as 1.45, 1.5, or 1.55. In some embodiments, the refractive index of the top metaunit 152 is different from the refractive index of the capping layer 510. In some embodiments, the top metaunit 152 can be made of an oxide or a nitride.

[0038] The same or similar components are labeled with the same or similar reference numbers, and descriptions of the same or similar components are not repeated in the following figures. It should be understood that some elements (e.g., light L) are not shown in the following figures for clarity.

[0039] 6 is a cross-sectional view of an optical device 600 according to one embodiment of the present disclosure. The difference between the optical device 600 of FIG. 6 and the optical device 100a of FIG. 5 is the number and arrangement of the lower meta units 140, the upper meta units 152, and the upper meta units 160.

[0040] Figure 7 is a top view of the color filter layer 120 and upper meta unit 160 of the optical device 600 of Figure 6. Figure 8 is a top view of the color filter layer 120 and lower meta unit 140 of the optical device 600 of Figure 6. Specifically, Figure 7 is a top view of the upper meta unit 160 of the optical device 600 in cross section along line D-D' in Figure 6, and Figure 8 is a top view of the lower meta unit 140 of the optical device 600 in cross section along line E-E' in Figure 6, with the color filter layer 120 shown for clarity.

[0041] As shown in FIGS. 6 and 7, upper meta unit 160 includes upper meta units 161-164 and 160b. Here, it can be understood that the numbers after "16" in upper meta units 161-164 correspond to the last numbers of color filters 121-124. Upper meta units 161-164 are arranged above color filters 121-124. Here, the "b" in upper meta unit 160b represents an upper meta unit arranged above the boundary of color filters 121-124. Upper meta units 161-164 and 160b are arranged along the X and Y directions and extend along the Z direction.

[0042] As shown in FIGS. 6 and 8, lower meta unit 140 includes lower meta units 141, 142, 144, and 140b. It can be understood that the numbers after "14" in lower meta units 141, 142, and 144 herein correspond to the last numbers of color filters 121, 122, and 124. Lower meta units 141, 142, and 144 are disposed above color filters 121, 122, and 124. Here, the "b" in lower meta unit 140b indicates a lower meta unit disposed above the boundary between color filters 121 to 124. Some of the lower meta units (such as lower meta units 141, 142, and 144) are disposed above color filters 121, 122, and 124, but not above color filter 123, as shown in FIG. 8.

[0043] As shown in FIG. 6, the optical device 600 includes an upper meta unit 160 disposed above a lower meta unit 140, where a capping layer 510 conformally and continuously lines the upper meta unit 160 (including upper meta units 161, 162, and 160b). Specifically, the capping layer 510 covers the top surface and sidewalls of the upper meta unit 160. As shown in FIG. 6, an internal space layer S is continuously disposed between the lower meta units 141, 142, and 140b and the upper meta units 161, 162, and 160b. An air recess 154 is disposed between each two adjacent upper meta units 160. Specifically, the upper meta unit 161 is disposed between two adjacent upper meta units 160b, and the upper meta unit 162 is disposed between two adjacent upper meta units 160b. See FIGS. 6-8. The axis of symmetry of color filter 121 coincides with the axis of symmetry of lower meta unit 141 and the axis of symmetry of upper meta unit 161. It should be understood that the combination of air recess 154 and at least one of upper meta unit 160 or capping layer 510 can be referred to as a "hybrid dielectric environment." In the embodiment of FIG. 6, upper meta layer TML is a combination of inner space layer S, upper meta unit 160, capping layer 510, and air recess 154. Lower meta layer BML is a combination of lower meta unit 140 and filler F1.

[0044] In some embodiments, the refractive index of the upper metaunits 160 is in the range of 1.4 to 2.6, such as 1.8, 2, 2.2, or 2.4. In some embodiments, the refractive index of the lower metaunits 140 is the same as the refractive index of the upper metaunits 160. In some embodiments, the upper metaunits 160 and / or the lower metaunits 140 can be made of Al2O3, SiO2, TiO2, Ta2O5, SiN, transparent organic materials, or combinations thereof. In some embodiments, the width of each of the lower metaunits 140 is in the range of 70 nm to 500 nm, such as 100, 200, 300, or 400 nm. In some embodiments, the width of each of the upper metaunits 160 is in the range of 70 nm to 500 nm, such as 100, 200, 300, or 400 nm. In some embodiments, the width of each of the lower metaunits 140 can be greater than, the same as, or less than the width of each of the upper metaunits 160. In some embodiments, the height of each of the lower metaunits 140 is in the range of 50 nm to 500 nm, such as 100, 200, 300, or 400 nm. In some embodiments, the height of each of the upper metaunits 160 is in the range of 50 nm to 500 nm, such as 100, 200, 300, or 400 nm. In some embodiments, the height of the internal space layer S is in the range of 0 to 500 nm, such as 50, 100, 200, 300, or 400 nm. In some embodiments, the thickness of the capping layer 510 (shown in FIGS. 5 and 6) is in the range of 20 nm to 150 nm, such as 50, 80, 100, 120, or 140 nm.

[0045] See FIG. 6. The upper metalayer TML and the lower metalayer BML function as phase adjustment layers. The upper metalayer TML has a light-receiving surface for light L. The light L passes through the upper metalayer TML (including the capping layer 510, the air recess 154, and the upper meta unit 160) and the lower metalayer BML (including the lower meta unit 140 and the filler F1), thereby gradually adjusting the phase difference. Specifically, the refractive indices of air (i.e., the air recess 154), the capping layer 510, the upper meta unit 160, the lower meta unit 140, and the underlayer 130 are different, providing sufficient interfaces with different refractive indices to adjust the phase difference. In other words, the more metalayers there are, the shorter the focal length of the light L therein can be, and the thickness (height h) of the underlayer 130 from the bottom surface 140s of the lower metalayer 140 to the top surface 120s of the color filter layer 120 (or the top surface 170s of the anti-reflection layer 170, as shown in FIG. 21) of the disclosed optical device can be reduced. The gradient of Δn of each metalayer (such as the upper metalayer TML, the middle metalayer MML, and the lower metalayer BML, described below) can effectively make the phase change more smoothly, ultimately shortening the focal length. Δn is |n environment -n meta defined by |n environment can be the effective refractive index. For example, if the hybrid dielectric environment is composed of air recess 154 and capping layer 510, the effective refractive index of the hybrid dielectric environment is between 1 and the refractive index of the upper meta unit (i.e., upper meta unit 160 shown in FIG. 6 or upper meta unit 152 shown in FIG. 5).

[0046] In an embodiment having an upper meta unit 160, referring to FIG. 6, when calculating the height h of the underlying layer 130, λ0 is the central wavelength of the design wavelength band of light L passing through the upper meta layer TML and the lower meta layer BML.

[0047] Figure 9 is a cross-sectional view of an optical device 900 according to one embodiment of the present disclosure. The difference between the optical device 900 of Figure 9 and the optical device 600 of Figure 6 is the placement of the lower meta unit 140. Figure 10 is a top view of the color filter layer 120 and the lower meta unit 140 of the optical device 900 of Figure 9. Specifically, Figure 10 is a top view of the lower meta unit 140 of the optical device 900 in cross section along line F-F' of Figure 9, with the color filter layer 120 shown for clarity.

[0048] More specifically, the lower meta unit 142 in FIG. 6 is replaced with the lower meta unit 142A in FIG. 9, where the size of the lower meta unit 142A is larger than the size of the lower meta unit 142. The lower meta unit 140b in FIG. 6 is replaced with the lower meta unit 140bf in FIG. 9. Here, it can be understood that the "f" in the lower meta unit 140bf represents "offset." As shown in FIG. 9, the axis of symmetry of the color filter 122 coincides with the axis of symmetry of the lower meta unit 142A. As shown in FIGS. 9 and 10, each of the lower meta units 140bf is disposed above the boundary between each of the color filters 121, 122, and 124 and is offset by a distance D. More specifically, based on the center of the lower meta unit 142A, as shown in FIG. 10, when the incident light is in the normal direction, each of the lower meta units 140bf in the X and Y directions is offset by the same distance D. The embodiment of FIG. 10 can be referred to as an "internal shift," which includes a "negative shift" and a "positive shift." It can be understood that a negative shift is named relative to a positive shift. For example, one of the lower meta units 140bf is shifted left, and one of the other lower meta units 140bf is shifted right. Also, one of the lower meta units 140bf is shifted up, and one of the other lower meta units 140bf is shifted down.

[0049] FIG. 11 is a cross-sectional view of an optical device 1100 according to one embodiment of the present disclosure. Differences between the optical device 1100 of FIG. 11 and the optical device 600 of FIG. 6 include the number of lower meta units 140. FIG. 12 is a top view of the color filter layer 120 and upper meta unit 160 of the optical device 1100 of FIG. 11. FIG. 13 is a top view of the color filter layer 120 and lower meta unit 140 of the optical device 1100 of FIG. 11. Specifically, FIG. 12 is a top view of the upper meta unit 160 of the optical device 1100 in cross section along line G-G' in FIG. 11, and FIG. 13 is a top view of the lower meta unit 140 of the optical device 1100 in cross section along line H-H' in FIG. 11, where the color filter layer 120 is shown for clarity.

[0050] It can be understood that the number and size of the upper meta units 160 and the lower meta units 140 can be adjusted according to the requirements of the optical device to achieve a reduction in the height h of the underlayer 130. As shown in FIG. 11 , the size of the upper meta units 160 is the same as the size of the lower meta units 140.

[0051] As shown in Figure 12, some of the upper meta units (such as upper meta units 161, 162, 164, and 160b) are arranged above color filters 121, 122, and 124, but are not arranged above color filter 123. As shown in Figure 13, lower meta units 141 to 144 are arranged above color filters 121 to 124, respectively.

[0052] FIG. 14A is a cross-sectional view of an optical device 1400 according to one embodiment of the present disclosure. The photoelectric conversion layer 110, color filter layer 120, lower meta layer BML, and upper meta layer TML are all shifted. It is understood that when one layer is shifted relative to another, it may be referred to as a "global shift." Therefore, the symmetry axes of the photodiode 112 under the color filter 121, the color filter 121, the lower meta unit 141, and the upper meta unit 161 are misaligned. Similarly, the symmetry axis of the lower meta unit 142 is misaligned with the symmetry axis of the upper meta unit 162. In some other embodiments, each of the lower meta units 140 of the lower meta layer BML may have an additional shift. Similarly, each of the upper meta units 160 of the upper meta layer TML may also have an additional shift; see the description of FIG. 14B below.

[0053] FIG. 14B is a top view of the color filter layer 120 and upper meta unit 160 according to another embodiment of the optical device 1400 of FIG. 14A. Midlines Mb1, Mb2, and Mb3 in FIGS. 14A and 14B represent the midlines of upper meta units 160b1, 160b2, and 160b3, respectively, in FIG. 14A. Midlines M1 and M2 in FIGS. 14A and 14B represent the midlines of upper meta units 161 and 162, respectively, in FIG. 14A. As shown in FIG. 14B, each of upper meta units 161, 162, 164, and 160b is offset by a different amount. Specifically, upper meta unit 160b1 has an offset distance d1, upper meta unit 161 has an offset distance d2, upper meta unit 160b2 is not shifted, upper meta unit 162 has an offset distance d3, and upper meta unit 160b3 has an offset distance d4. The offset distances d1-d4 may be the same or different from one another. Because the shift in upper meta unit 160 of FIG. 14B is in the upper meta layer TML, the embodiment of FIG. 14B may be referred to as "internal shift." More specifically, upper meta unit 160b1 may be referred to as "negative shift," and each of upper meta units 161, 162, and 160b3 may be referred to as "positive shift."

[0054] FIG. 15 is a cross-sectional view of an optical device 1500 according to one embodiment of the present disclosure. FIG. 16 is a top view of the color filter layer 120 of the optical device 1500 of FIG. 15. The difference between the optical device 1500 of FIG. 15 and the optical device 600 of FIG. 6 is the number of photodiodes 112. Specifically, as shown in FIG. 16, each of the color filters 121-124 corresponds to four photodiodes 112 (QPD). The pixel dimension p (including pixel length or pixel width) is also determined by the distance between two adjacent DTIs 114. In the embodiment of the optical device 1500, the height h of the underlayer 130 from the bottom surface 140s of the lower meta unit 140 to the top surface 120s of the color filter layer 120 is based on the following equation:

number

[0055] 6, 9, 11, 14A, and 15. The lower meta units 140 in the optical devices 600, 900, 1100, 1400, and 1500 are arranged in a layer along the X direction, and the lower meta units 140 connect to the upper meta units 160.

[0056] 17A and 17B are cross-sectional views of optical devices 1700A and 1700B according to some embodiments of the present disclosure. The photoelectric conversion layer 110 further includes multiple internal deep trench isolations (DTIs) 113 to separate pixels with two photodiodes (DPDs) 112. The difference between the optical device 1700A of FIG. 17A and the optical device 600 of FIG. 6 is the internal DTIs 113 and the number of photodiodes 112. The difference between the optical device 1700A of FIG. 17A and the optical device 1700B of FIG. 17B is the internal DTIs 113. As shown in FIG. 17A, the photodiodes 112 are spaced apart by the internal DTIs 113 and DTIs 114. Note that each of the internal DTIs 113 is disposed between two adjacent DTIs 114. Therefore, the DTIs 114 can also be understood as "external DTIs 114." As shown in FIG. 17B, there are no internal DTIs 113 disposed between the external DTIs 114, and two photodiodes 112 are disposed between two adjacent external DTIs 114.

[0057] 17A and 17B, showing the photodiodes 112. Specifically, each of the color filters 121-124 corresponds to two photodiodes 112 (DPDs), and the pixel dimension p (including pixel length or pixel width) is determined by the distance between two adjacent external DPDs 114.

[0058] 18A and 18B are cross-sectional views of optical devices 1800A and 1800B according to some embodiments of the present disclosure. Specifically, the difference between optical device 1700A in FIG. 17A and optical device 1800A in FIG. 18A is the placement of photodiode 112 below color filter 121. Similarly, the difference between optical device 1700B in FIG. 17B and optical device 1800B in FIG. 18B is also the placement of photodiode 112 below color filter 121.

[0059] FIG. 18C is a top view of the color filter layer 120 of the optical devices 1800A, 1800B of FIGS. 18A and 18B, showing the photodiode 112. The difference between FIG. 17C and FIG. 18C is the placement of the photodiode 112 under the color filter 121. Specifically, as shown in FIG. 17C, the photodiode 112 is positioned below the color filter 121. under All of the photodiodes 112 extend in the Y direction and are arranged along the X direction. under The photodiodes 112 extend along the X direction and are arranged along the Y direction. under Each photodiode 112 extends in the Y direction and is arranged along the X direction. In Figure 18C, it can be seen that each of the color filters 121-124 corresponds to two photodiodes 112 (DPDs), and the pixel dimension p (including pixel length or pixel width) is determined by the distance between two adjacent external DTIs 114.

[0060] In the embodiment of FIGS. 17A-17C and the embodiment of FIGS. 18A-18C, the height h of the underlayer 130 from the bottom surface 140s of the lower meta unit 140 to the top surface 120s of the color filter layer 120 is based on the following formula:

number

[0061] FIG. 19 is a cross-sectional view of an optical device 1900 according to some embodiments of the present disclosure. Differences between the optical device 1900 of FIG. 19 and the optical device 600 of FIG. 6 include the number of metalayers, including a top metalayer TML, a middle metalayer MML, and a bottom metalayer BML. The middle metalayer MML is disposed between the top metalayer TML and the bottom metalayer BML. The middle metalayer MML includes multiple middle meta units 180, and the material of the middle meta units 180 is the same as the material of the top meta unit 160 and / or the bottom meta unit 140. Specifically, air recesses 154 are disposed above the middle meta units 180. The patterns (arrangements) of the bottom meta units 140, the middle meta units 180, and the top meta units 160 may be the same or different.

[0062] FIG. 20 is a cross-sectional view of an optical device 2000 according to some embodiments of the present disclosure. The optical device 2000 includes an upper meta layer TML, a middle meta layer MML, and a lower meta layer BML. The middle meta layer MML includes middle meta units 180 arranged in a first layer L1 and a second layer L2. The middle meta units 180 of the optical device 2000 are arranged along the X direction. In such an embodiment, the lower meta layer BML can be referred to as the third layer L3. As shown in FIG. 20, the first layer L1 (middle meta units 180) connects to the upper meta unit 160, and the second layer L2 (middle meta units 180) connects to the third layer L3 (i.e., the lower meta layer BML), with the first layer L1 and the second layer L2 being separated by an underlayer 130a. In the embodiment of FIG. 20, the underlayer 130a is disposed between the first layer L1 and the second layer L2. The material of the underlayer 130a is the same as the material of the underlayer 130. The material of the intermediate metaunits 180 is the same as the material of the upper metaunits 160 and / or the lower metaunits 140. The patterns (arrangements) of the lower metaunits 140, intermediate metaunits 180, and upper metaunits 160 may be the same or different.

[0063] FIG. 21 is a cross-sectional view of an optical device 2100 according to some embodiments of the present disclosure. The optical device 2100 of FIG. 21 is similar to the optical device 2000 of FIG. 20, but differs in the pattern (arrangement) of different meta units. Specifically, the pattern of the lower meta unit 140 of FIG. 20 differs from that of FIG. 21, the pattern of the middle meta unit 180 of FIG. 20 differs from that of FIG. 21, and the pattern of the upper meta unit 160 of FIG. 20 differs from that of FIG. 21. Furthermore, as shown in FIG. 21, the optical device 2100 does not include a color filter layer 120. In such an embodiment, the height h of the underlying layer 130 from the bottom surface 140s of the third layer L3 (lower meta unit 140) to the top surface 170s of the anti-reflection layer 170 is based on the above equation, where the pixel dimension p is determined by the distance between two adjacent DTIs 114. 21 has one photodiode 112 corresponding to one color filter (color filters 121, 122), it can be understood that four photodiodes 112 (QPD) also apply to other embodiments (i.e., four photodiodes 112 corresponding to one color filter, as shown in FIGS. 15 and 16). The number and size of each layer (i.e., first layer L1, second layer L2, and third layer L3) of optical device 2000 of FIG. 20 and optical device 2100 of FIG. 21 can be adjusted to achieve a reduction in height h of the underlying layer 130.

[0064] Figures 22A through 22G are cross-sectional views of various stages in fabricating the optical device 600 of Figure 6. It will be understood that additional operations can be provided before, during, and after the process illustrated by Figures 22A through 22G, and that some of the operations described below can be replaced or eliminated for additional embodiments of the process. The order of the operations / processes is interchangeable.

[0065] As shown in FIG. 22A, a stacked device is provided, which includes material layers of a photoelectric conversion layer 110, an anti-reflection layer 170, a color filter layer 120, and an underlayer 130. As shown in FIGS. 22A and 22B, a patterned photoresist mask PR1 having a plurality of openings is formed on the underlayer 130. As shown in FIGS. 22B and 22C, an etching process is performed through the patterned photoresist mask PR1 to form the underlayer 130 in a pattern having a plurality of openings. As shown in FIGS. 22C and 22D, a material layer of a lower meta unit 140 fills the openings in the underlayer 130 before performing a chemical mechanical planarization process.

[0066] As shown in Figures 22D and 22E, a patterned photoresist mask PR2 having a plurality of openings is formed on the underlayer 130. As shown in Figures 22E and 22F, an etching process is performed using the patterned photoresist mask PR2 to form upper meta units 160 with a pattern having a plurality of openings, with the lower meta units 140 embedded in the upper portions of the underlayer 130 and the internal space layer S remaining on the lower meta units 140. In an embodiment in which the internal space layer S remains, a portion of the upper surface of the internal space layer S is exposed. In another embodiment, the internal space layer S does not remain on the lower meta units 140 during the etching process from Figures 22E to 22F, and a portion of the upper surface of the underlayer 130 is exposed. As shown in Figures 22F and 22G, a capping layer 510 is formed on the upper surface and sidewalls of the upper meta units 160 and on the exposed upper surface of the internal space layer S.

[0067] The present disclosure provides a multilayer metasurface with a hybrid dielectric environment stacked on a CIS to shorten the focal length of light. After light passes through different materials (hybrid dielectric environments) with different refractive indices, the light energy tends to concentrate over a shorter distance. Therefore, the focal length of light can be shortened. As a result, the thickness of the underlying layers of the disclosed optical device can be reduced, thereby reducing the overall dimensions of the optical device and improving the performance of the optical device.

[0068] The foregoing outlines features of some embodiments so that those skilled in the art may better understand aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use this disclosure as a basis for designing or modifying other processes and structures to carry out the same purposes and / or achieve the same advantages of the embodiments introduced herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that those skilled in the art may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. [Explanation of symbols]

[0069] 100, 100a, 600, 900, 1100, 1400, 1500, 1700A, 1700B, 1800A, 1800B, 1900, 2000, 2100...optical device, 110...photoelectric conversion layer, 112...photodiode, 113, 114...deep trench isolation (DTI), 120...color filter layer, 120s...top surface, 121, 122, 123, 124...color filter, 125...separation grid, 126...metal grid, 130, 130a...underlayer, 140, 140b, 140bf, 141, 142, 142A, 144...lower meta unit, 140s...bottom surface, 152, 152b, 152c1, 152c4, 160, 161, 162, 163, 164, 160b, 160b1, 160b2, 160b3...upper meta unit, 154...air recess, 170...anti-reflection layer, 180...middle meta unit, 510...capping layer. BML...bottom meta layer, d1, d2, d3, d4...offset distance, F1...filling, h...height, L...light, L1...first layer, L2...second layer, M1, M2, Mb1, Mb2, Mb3...midline, MML...middle meta layer, p...pixel dimension, PR1, PR2...photoresist mask, S...internal space layer, TML...top meta layer.

Claims

1. A photoelectric conversion layer including a plurality of photodiodes; an antireflection layer disposed on the photoelectric conversion layer; an underlayer disposed above the anti-reflection layer; a lower metalayer disposed on the underlayer, the lower metalayer including a plurality of lower metaunits and a filler between the lower metaunits, the filler extending continuously from the underlayer, the material of the filler being the same as the material of the underlayer; an upper metalayer disposed above the lower metalayer, the upper metalayer including a plurality of upper meta units and a plurality of air recesses, each of the plurality of air recesses being disposed between two adjacent upper meta units; Including, an optical device comprising: a width of each of the lower metaunits in the range of 70 nm to 500 nm; a width of each of the upper metaunits in the range of 70 nm to 500 nm; an effective refractive index of the upper metalayer in the range of 1.3 to 1.6; a refractive index of the lower metaunits in the range of 1.4 to 2.6; and a refractive index of the underlayer in the range of 1.2 to 1.8; and the refractive index of the lower metaunits is greater than the refractive index of the underlayer.

2. The optical device of claim 1, wherein the photoelectric conversion layer further includes a plurality of deep trench isolations isolating each of the photodiodes, and a height of the underlayer from a bottom surface of the lower meta-unit to an upper surface of the anti-reflection layer is based on the following formula: [0010] where h is the height of the underlayer from the bottom surface of the lower meta-unit to the top surface of the anti-reflective layer; ht is the theoretical height of the underlayer, p is the pixel size, which is determined by the distance between two adjacent deep trench isolations; n is the refractive index of the underlayer, λ ０ is a central wavelength of a design wavelength band of light passing through the upper metalayer and the lower metalayer.

3. further comprising a color filter layer disposed between the anti-reflection layer and the undercoat layer; 3. The optical device of claim 2, wherein the color filter layer includes a plurality of color filters, each of which corresponds to one or two photodiodes, and the height of the underlayer is from the bottom surface of the lower meta unit to the top surface of the color filter layer.

4. the color filter layer includes a first color filter, a second color filter, and a third color filter; 4. The optical device of claim 3, wherein the lower meta units are disposed above the first color filter and the second color filter, but not above the third color filter.

5. 2. The optical device of claim 1, further comprising a capping layer conformally and continuously backing said plurality of upper meta units and said plurality of air recesses, said plurality of air recesses remaining in said upper meta layer.

6. 6. The optical device of claim 5, wherein the refractive index of the upper meta unit is in the range of 1.4 to 2.6, the refractive index of the capping layer is in the range of 1.4 to 1.6, and the refractive index of the upper meta unit is different from the refractive index of the capping layer.

7. 2. The optical device of claim 1, wherein the upper metalayer has a global shift relative to the lower metalayer, the global shift being defined by edges of the upper metalayer being offset from corresponding edges of the lower metalayer, and the upper metaunits of the upper metalayer have an internal shift, the internal shift being defined by midlines of each of the upper metaunits being offset a distance from the original midlines of each of the upper metaunits.

8. 2. The optical device of claim 1, further comprising an intermediate metalayer disposed between the upper metalayer and the lower metalayer, the intermediate metalayer including a plurality of intermediate meta units disposed in a first layer and a second layer, the first layer connecting to the upper meta units and the second layer connecting to the lower metalayer, the first layer and the second layer being separated by the underlayer.

9. The photoelectric conversion layer further includes a color filter layer and an inner spacing layer, the color filter layer being disposed between the photoelectric conversion layer and the underlayer, the inner spacing layer being disposed continuously between the lower meta units and the upper meta units, and the photoelectric conversion layer further includes a plurality of deep trench isolations separating each of the photodiodes; 2. The optical device of claim 1, wherein the color filter layer includes a plurality of color filters, each of which corresponds to four photodiodes, and the height of the underlayer from the bottom surface of the lower meta unit to the top surface of the color filter layer is based on the following formula: [0025] where h is the height of the undercoat layer from the bottom surface of the lower meta unit to the top surface of the color filter layer; ht is the theoretical height of the underlayer, p is the pixel size, which is determined by the distance between two adjacent deep trench isolations; n is the refractive index of the underlayer, λ ０ is a central wavelength of a design wavelength band of light passing through the upper metalayer and the lower metalayer.

10. The present invention further includes a color filter layer and an internal spacing layer, the color filter layer being disposed between the photoelectric conversion layer and the underlayer, and the internal spacing layer being disposed continuously between the plurality of lower meta units and the plurality of upper meta units; the color filter layer includes a first color filter, a second color filter, and a third color filter; the lower meta units are disposed above the first color filter, the second color filter, and the third color filter; 2. The optical device of claim 1, wherein the plurality of upper meta units are disposed above the first color filter and the second color filter, but not above the third color filter.

11. The present invention further includes a color filter layer and an internal spacing layer, the color filter layer being disposed between the photoelectric conversion layer and the underlayer, and the internal spacing layer being disposed continuously between the plurality of lower meta units and the plurality of upper meta units; 2. The optical device of claim 1, wherein the color filter layer includes a first color filter and a second color filter, the photodiodes below the first color filter extend along a first direction and are aligned along a second direction substantially perpendicular to the first direction, and the photodiodes below the second color filter extend along the second direction and are aligned along the first direction.

12. The present invention further includes a color filter layer and an internal spacing layer, the color filter layer being disposed between the photoelectric conversion layer and the underlayer, and the internal spacing layer being disposed continuously between the plurality of lower meta units and the plurality of upper meta units; 2. The optical device of claim 1, wherein an axis of symmetry of each of the lower meta units is offset from an axis of symmetry of each of the upper meta units.

13. The present invention further includes a color filter layer and an internal spacing layer, the color filter layer being disposed between the photoelectric conversion layer and the underlayer, and the internal spacing layer being disposed continuously between the plurality of lower meta units and the plurality of upper meta units; 2. The optical device of claim 1, wherein the lower meta unit is disposed in one layer, the lower meta unit connecting to the upper meta unit.

14. The present invention further includes a color filter layer and an internal spacing layer, the color filter layer being disposed between the photoelectric conversion layer and the underlayer, and the internal spacing layer being disposed continuously between the plurality of lower meta units and the plurality of upper meta units; the refractive index of the upper metaunit is in the range of 1.4 to 2.6, and the refractive index of the lower metaunit is the same as the refractive index of the upper metaunit; 2. The optical device of claim 1, wherein the refractive index of the internal spacing layer is the same as or different from the refractive index of the lower meta unit and the refractive index of the upper meta unit.

15. The present invention further includes a color filter layer and an internal spacing layer, the color filter layer being disposed between the photoelectric conversion layer and the underlayer, and the internal spacing layer being disposed continuously between the plurality of lower meta units and the plurality of upper meta units; The optical device of claim 1, wherein the height of each of the lower meta units is in the range of 50 nm to 500 nm, the height of each of the upper meta units is in the range of 50 nm to 500 nm, and the height of the internal spacing layer is in the range of 0 to 500 nm.

Images