Patent ID: 12256575

DETAILED DESCRIPTION

Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

FIG.1is a top view of an image sensor10according to one embodiment of the present embodiment.FIG.2is a three-dimensional view of a first pixel array100of the image sensor10inFIG.1. Reference is made toFIG.1andFIG.2. The image sensor10includes four first pixel arrays100. The first pixel array100is a multi photo diode structure applied in an image sensor such as CMOS image sensor (CIS). The first pixel array100includes a polyhedron structure110, a photoelectric conversion layer120, a color filter130, and an under layer140. The photoelectric conversion layer120includes multiple photo diodes122. The polyhedron structure110is located above the photoelectric conversion layer120, the under layer140, and the color filter130. The color filter130is located between the under layer140and the photoelectric conversion layer120. The under layer140is located between the blue color filter layer130and the polyhedron structure110.

The polyhedron structure110includes a bottom facet112, a top facet114, and at least one side facet116. An area of the bottom facet112is greater than an area of the top facet114, and a number of the side facets116is greater than or equal to three. The bottom facet112is located between the side facets116and the under layer140. An orthogonal projection of the polyhedron structure110overlaps with more than or equal to two photo diodes122. In the present embodiments, the polyhedron structure110has four side facets116. In other words, the polyhedron structure110is a hexahedron. The polyhedron structure110is transparent, and the material of the polyhedron structure110includes photoresist, plastic, organic material, inorganic material, or other suitable materials.

In the present embodiment, the first pixel array100has four pixels12, and each of the pixels12has one photo diode122. Therefore, the orthogonal projection of the polyhedron structure110overlaps with four photo diodes122. That is, the first pixel array100is a quad photo diode (QPD). In some embodiments, the under layer140and the filter layer130can be omitted, or other structures can be disposed between the polyhedron structure110and the photoelectric conversion layer120.

FIG.3is a schematic of optical path of an incident light L1traveling through a polyhedron structure110. The polyhedron structure110is configured to divide an incident light L1into multiple light beams. Each of the light beams is respectively focused in each of the photo diodes. The number of the light beam is determined by a number of the side facets116so as to improve performance of the photo diodes122. For example, the polyhedron structure110can divide the incident light L1into five light beams each passes through the side facets116and the top facet114. Only three light beams are demonstrated inFIG.3. A light beam L2and a light beam L3respectively travel toward the photo diodes122, and a portion of the incident light L1travels downward.

A position of the focus of the light beam is determined by the area of the top facet114. For example, if a height H1of the polyhedron structure110is fixed, the inclined level of the side facets116becomes greater when the area of the top facet114increases. As a result, focal lengths of the light beams L2, L3are shorter. Therefore, the direction of the light beams L2, L3can be adjusted by controlling the area of the top facet114. As such, focuses of the light beams L2, L3are positioned more correlated with positions of photo diodes.

FIGS.4A to4Eare schematics of various polyhedron structures according to some embodiments of the present disclosure.FIGS.5A to5Eare top views of the polyhedron structures shown inFIGS.4A to4E. As shown inFIG.4AandFIG.5A, the polyhedron structure110ais a tetrahedron, and the polyhedron structure110ahas a triangular pyramid shape. The polyhedron structure110aincludes three vertexes111aformed by the bottom facet112aand the side facets116aand a vertex113aabove the side facets116a.

As shown inFIG.4BandFIG.5B, the polyhedron structure110bis a pentahedron, and the polyhedron structure110ahas a quadrangular pyramid shape. The polyhedron structure110bincludes four vertexes111bformed by the bottom facet112band the side facets116band a vertex113bformed by the side facets116b.

As shown inFIG.4CandFIG.5C, the polyhedron structure110cis a pentahedron, and the polyhedron structure110chas a triangular column shape. The polyhedron structure110cincludes three vertexes111cformed by the bottom facet112cand the side facets116cand three vertexes111cformed by the top facet114cand the side facets116c. As shown inFIG.4DandFIG.5D, the polyhedron structure110dis a pentahedron, and the polyhedron structure110dhas a roof shape. The polyhedron structure110dincludes four vertexes111dformed by the bottom facet112dand the side facets116dand two vertexes formed by side facets116d. As shown inFIGS.4E and5E, the polyhedron structure110eis a hexahedron, and the polyhedron structure110ehas a pentagonal pyramid shape. The polyhedron structure110eincludes five vertexes111eformed by the bottom facet112eand the side facets116eand a vertex113eformed by the side facets116e.

FIGS.6A to6Dare schematics of various polyhedron structures according to some embodiments of the present disclosure.FIGS.7A to7Dare illuminance diagram of the photo diodes in combination with the polyhedron structures shown inFIGS.6A to6D. As shown inFIG.6AandFIG.7A, the polyhedron structure110fhas eight side facets116f, and therefore an incident light is divided into eight light beams. As shown inFIG.6BandFIG.7B, the polyhedron structure110ghas eight side facets116gand a top facet114g, and therefore an incident light is divided into nine light beams. As shown inFIG.6CandFIG.7C, the polyhedron structure110hhas a cone shape (i.e., infinite number of side facets), and therefore an incident light is reshaped as a ring-shaped light. As shown inFIG.6DandFIG.7D, the polyhedron structure110ihas a cone shape with a top facet116i, and therefore an incident light is reshaped as a ring-shaped light and a light beam at the center of the ring-shaped light.

The polyhedron structure of the present discloser is not limited to those embodiments described above inFIGS.4A to44EandFIGS.6A to6D. Suitable shapes of the polyhedron structures can be used based on the arrangement of pixels so as improve performance of the photo diodes. As such, focuses of the light beams are positioned more correlated with positions of photo diodes.

Reference is made toFIG.1. A refractive index of the polyhedron structure110is greater than or equal to 1.1 and is smaller than a refractive index of the photo diodes122. Specifically, the refractive index of the photo diodes122is greater than a refractive index of the color filter130, and the refractive index of the color filter130is greater than a refractive index of the under layer140. The refractive index of the under layer140is greater than or equal to the refractive index of the polyhedron structure110. With such configuration, light transmission efficiency and performance of the photo diodes122can be improved.

FIG.8is a side view of a first pixel array100aaccording to one embodiment of the present disclosure. The first pixel array100ais similar to the first pixel array100shown inFIG.2, and the difference is that the first pixel array100afurther includes an antireflection layer150coated on the polyhedron structure110. In the present embodiment, a refractive index of the antireflection layer150is greater than 1.1 and is smaller than a refractive index of the polyhedron structure110. With such configuration, light transmission efficiency and performance of the photo diodes122can be further improved.

FIGS.9A to9Dare top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.9A, the image sensor10ahas sixty-four photo diodes122(i.e., sixty-four pixels) and sixteen polyhedron structures110. The polyhedron structures110are arranged as a 4×4 array. Each of the polyhedron structures110overlaps with four photo diodes122which are arranged as a 2×2 array. As shown inFIG.9B, the image sensor10bhas eighty-one photo diodes122and nine polyhedron structures110. The polyhedron structures110are arranged as a 3×3 array. Each of the polyhedron structures110is overlapped with nine photo diodes122which are arranged as a 2×2 array. As shown inFIG.9C, the image sensor10chas sixty-four photo diodes122and four polyhedron structures110. The polyhedron structures110are arranged as a 2×2 array. Each of the polyhedron structures110overlaps with sixteen photo diodes122which are arranged as a 4×4 array. As shown inFIG.9D, the image sensor10dhas one hundred photo diodes122and four polyhedron structures110. The polyhedron structures110are arranged as a 2×2 array. Each of the polyhedron structures110overlaps with twenty-five photo diodes122which are arranged as a 5×5 array. The present disclosure is not limited to those configurations shown inFIGS.9A to9D.

FIG.10Ais a schematic of a polyhedron structure110j.FIG.10BandFIG.10Care top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.10AandFIG.10B, the image sensor10eincludes nine third pixel arrays100c. Each of the third pixel arrays100cincludes one polyhedron structures110jand nine photo diodes122(i.e., nine pixels). Each of the polyhedron structures110jhas eight side facets116, a square bottom facet112and a circular top facet114. Each of the polyhedron structures110joverlaps with nine photo diodes122arranged as a 3×3 array. Therefore, a sum of a number of the side facets116and a number of the top facet114of the polyhedron structure110jis equal to a number of the photo diodes122.

As shown inFIG.10C, the image sensor10fhas four fourth pixel arrays100d. Each of the fourth pixel arrays100dincludes one polyhedron structure110kand sixteen photo diodes122. The polyhedron structure110kis similar to polyhedron structure110j, and the difference is that the polyhedron structure110khas sixteen side facets116. Each of the polyhedron structures110koverlaps with sixteen photo diodes122arranged as a 4×4 array. Therefore, a sum of a number of the side facets116and a number of the top facet114of the polyhedron structure110kequals to the number of the photo diodes122.

In the embodiments shown inFIG.10BandFIG.10C, the polyhedron structure110jand the polyhedron structure110kare prism. The energy of an incident light can be distributed more uniformly to the one or more pixels underlying the top fact114and the pixels underlying the side facets116.

FIG.11AandFIG.11Bare top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.11A, the image sensor10gincludes fourteen first pixel arrays100A and one second pixel array100B. The first pixel arrays100A is the same as the first pixel array100described inFIG.2. The second pixel array100B has eight photo diodes122arranged as a 4×2 array, and there is no polyhedron structure110located above the photo diodes122of the second pixel array100B. As shown inFIG.11B, the image sensor10hincludes twelve first pixel arrays100A and one second pixel array100B. The second pixel array100B includes sixteen photo diodes122arranged as a 4×4 array, and there is no polyhedron structures110located above the photo diodes122of the second pixel array100B. The configurations of the image sensor10gand the image sensor10hcan be utilized for specific functions such as auto focus function. In some other embodiments, the pixel arrays which have no polyhedron structures can be randomly arranged in the image sensor.

FIGS.12A to12Care top view of image sensors according to some embodiments of the present disclosure. As shown inFIG.12A, the image sensor10iincludes fourteen first pixel array100A and one second pixel array100B. Each of the first pixel arrays100A includes a polyhedron structure110and four photo diodes122. Each of the polyhedron structure110overlaps with four photo diodes122as described inFIG.1. The second pixel array100B includes one polyhedron structure110I and eight photo diodes122arranged as a 4×2 array. The polyhedron structure110I has a rectangular top facet114I and a rectangular bottom facet112I. The polyhedron structure110and the polyhedron structure110I are both Hexahedron, but a volume of the polyhedron structure110I is greater than a volume of the polyhedron structure110. In other words, a volume of the polyhedron structure110of the first pixel array100A is different from a volume of the polyhedron structure110I of the second pixel array1001B. An area of the bottom facet112(seeFIG.2) of the polyhedron structure110of the first pixel array100A is different from an area of the bottom facet112I of the polyhedron structure110I of the second pixel array100B. An area of the top facet114(seeFIG.1) of the polyhedron structure110of the first pixel array100A is different from an area of the top facet114I of the polyhedron structure110I of the second pixel array100B.

As shown inFIG.12B, the image sensor10jis similar to the image sensor10ishown inFIG.12A, and the difference is that the top facet114mof the polyhedron structure110mhas an elliptical shape. In other words, the polyhedron structure110of the first pixel array100A and the polyhedron structure110mof the second pixel array100B have different shapes.

As shown inFIG.12C, the image sensor10kincludes twelve first pixel array100A and one second pixel array100B. The second pixel array100B has one polyhedron structure110nand sixteen photo diodes122arranged as a 4×4 array. The polyhedron structure110nhas a circular top facet114nand a rectangular bottom facet112n. The polyhedron structure110nhas an octagonal column shape. In other words, a number of the side facets116of the polyhedron structure110of the first pixel array100A is different from a number of the side facets116nof the polyhedron structure110nof the second pixel array100B.

FIGS.13A to13Care top view of image sensors according to some embodiments of the present disclosure. As shown inFIG.13A, the image sensor10I includes four first pixel arrays100. Each of the first pixel arrays100has a polyhedron structure110oand four pixels12. The image sensor10I has a RGGB mosaic pattern. The upper-right first pixel array100has a blue color filter130B, and the lower-left first pixel array100has a red color filter130R. The other first pixel arrays100each has a green color filter130G. In the present embodiment, the size of each of the polyhedron structure110ois smaller than the size of the underlying layers. For example, as shown in the upper-right first pixel array100, an area of an orthogonal projection of the polyhedron structure110ois smaller than an area of the blue color filter130B.

As shown inFIG.13B, the image sensor10mis similar to the image sensor10I shown inFIG.13A, and the difference is that the image sensor10mhas three polyhedron structures110oand one polyhedron structure110. The polyhedron structure110is located above the blue color filter130B. The size of the polyhedron structure110is greater than the sizes of the polyhedron structures110o. In the present embodiment, an area of an orthogonal projection of the polyhedron structure110on the blue color filter130B is substantially the same as the area of blue the color filter130B. With such design, energy efficiency of each of the pixel arrays100can be adjusted based on the color filter arrangement so as to improve performance of the image sensor10m.

As shown inFIG.13C, the image sensor10nis similar to the image sensor10mshown inFIG.13B, and the difference is that the image sensor10nhas two polyhedron structures110o, one polyhedron structure110, and one polyhedron structure110pabove the red color filter130R. The size of the polyhedron structure110pis smaller than the sizes of the polyhedron structures110oand the size of the polyhedron structures110. With such design, energy efficiency of each of the pixel arrays100can be adjusted based on the color filter arrangement so as to improve performance of the image sensor10m.

FIG.14Ais a side view of an image sensor100according to one embodiment of the present disclosure.FIG.14Bis a top view of the image sensor100inFIG.14A. Reference is made toFIG.14AandFIG.14B, the image sensor100includes a first pixel array100A and a second pixel array100B. Each of the first pixel array100A and the second pixel array100B includes four photo diodes122, a polyhedron structure110, and a color filter130located between the photo diodes122and the polyhedron structure110. The image sensor100further includes a grid160located between the color filters130of the first pixel array100A and the second pixel array100B. The polyhedron structure110has a translational shift relative to the color filter130and the photo diodes122.

As shown inFIG.14B, an orthogonal projection of the polyhedron structure110of the first pixel array100A overlaps with the color filter130of the second pixel arrays100B and the gird160. As shown inFIG.14A, the incident L1can be divided into two light beams L2, L3by the polyhedron structure110of the first pixel array100A. The light beam L3travels toward the photo diodes122of the second pixel array100B, and the light beam L2travels toward the photo diodes122of the first pixel array100A. Accordingly, the image sensor100and the image sensor10have the same advantages.

As shown inFIG.14B, a displacement d1between a center C1of the polyhedron structure110of the first pixel array100A and a center C3of the first pixel array100A in the plan view is the same as a displacement d2between a center C2of the polyhedron structure110of the second pixel array100B and a center C4of the second pixel array100B in the plan view. In some other embodiments, the displacement d1and the displacement d2can be different.

FIG.14CandFIG.14Dare top views of the image sensors according to some embodiments of the present disclosure. As shown inFIG.14C, the image sensor10pincludes a blue color filter130B, a red color filter130R, and two green color filters130G. In the present embodiment, a displacement d3between the center of the polyhedron structures110and the center of the first pixel array100A is different from a displacement d4between a center of the polyhedron structure110of the second pixel array100B and a center of the second pixel array100B. In other words, the displacement d3between the polyhedron structure110qand the first pixel array100A having a blue color is different from the displacement d4between the polyhedron structure110rand the second pixel array100B having a red color. As shown inFIG.14D, the image sensor10qis similar to the image sensor10q. The displacement d5and the displacement d6are different from the displacement d3and the displacement d4based on the ray direction R of the incident light. In other words, the polyhedron structures110can have independent displacements relative to the centers of the pixel arrays. Accordingly, the displacements can be adjusted based on a ray direction R of the incident light and a color filter arrangement. With such configuration, the performance of the image sensor10pand the image sensor10qcan be improved.

FIGS.15A to15Eare cross-sectional views of image sensors according to some embodiments of the present disclosure. As shown inFIG.15A, the image sensor10rincludes two first pixel arrays100. Each of the first pixel arrays100includes four photo diodes122, a color filter130, and a polyhedron structure110. The image sensor10rfurther includes a grid160surrounding the color filters130. The grid160includes a body portion162and a metal layer portion164. The metal layer portion164is located between the body portion162and the photo diodes122. In some embodiments, a refractive index of the body portion162is greater than 1.5. In some other embodiments, a refractive index of the body portion162is greater than or equal to 1.0 and is smaller than 1.5.

As shown inFIG.15B, the image sensor10sis similar to the image sensor10r, and the difference is that the grid160aof the image sensor10shas no metal layer portion164. The refractive index of the grid160ais greater than or equal to 1.0 and is smaller than 1.5. Since the grid160ahas no metal layer and the refractive index is lower, the efficiency of the image sensor10scan be improved.

As shown inFIG.15C, the image sensor10tis similar to the image sensor10sas shown inFIG.15B, and the difference is that the grid160bof the image sensor10tincludes a first layer166and a second layer168, and the refractive indexes materials of the first layer166and the second layer168are different. For example, the refractive index of second layer168is greater than 1.5, and the refractive index of the first layer166is greater than or equal to 1.0 and is smaller than 1.5. In the present embodiment, the second layer168covers and surrounds the first layer166. In other words, the first layer166is embedded in the second layer168. Since the effective refractive index of the grid160bis lower, the efficiency of the image sensor10tcan be improved.

As shown inFIG.15D, the image sensor10uis similar to the image sensor10tas shown inFIG.15C, and the difference is the configuration of the grid160c. In the present embodiment, the first layer166of the grid160cis located above the second layer168of the grid160cof the image sensor10u. Since the refractive index of the grid16cis lower, the efficiency of the image sensor10ucan be improved.

As shown inFIG.15E, the image sensor10vis similar to the image sensor10uas shown inFIG.15D, and the difference is the configuration of the grid160d. In the present embodiment, the second layer168of the grid160dhas a greater diameter than a diameter of the first layer166of the grid160d. Since the refractive index of the grid160dis lower, the efficiency of the image sensor10vcan be improved.

FIGS.16A to16Eare top views of color arrangement of the color filters of the image sensors according to some embodiments of the present disclosure. Each pixel arrays100shown inFIGS.16A to16Eare substantially the same as the pixel array shown inFIG.1andFIG.2. For convenience, only colors of the color filters are demonstrated herein, and the polyhedron structures and the photo diodes are omitted inFIGS.16A to16E. As shown inFIG.16A, the image sensor20has a RGGB arrangement. That is, the image sensor20includes color filters corresponding to red, green, and blue. As shown inFIG.16B, the image sensor20ahas a RGBW arrangement. That is, the image sensor20aincludes color filters corresponding to red, green, blue, and white. As shown inFIG.16C, the image sensor20bhas a CYYM arrangement. That is, the image sensor20bincludes color filters corresponding to cyan, yellow, and magenta. As shown inFIG.16D, the image sensor20chas a RYYB arrangement. That is, the image sensor20cincludes color filters corresponding to red, yellow, and blue. As shown inFIG.16E, the image sensor20dhas a RGBIR arrangement. That is, the image sensor20dincludes color filters corresponding to red, green, blue, and infrared.

FIGS.17A to17Dare top views of image sensors according to some embodiments of the present disclosure. For convenience, only colors of the color filters are demonstrated herein. As shown inFIG.17A, the image sensor20eincludes four fifth pixel arrays100e. Each of the fifth pixel arrays100eincludes four pixels and has a RGGB arrangement. In other words, the polyhedron structure110of each of the fifth pixel array100eoverlaps with four photo diodes122and four color filters including different colors (red, green, and blue). That is, an orthogonal projection of each of the polyhedron structure110overlaps with the color filters having at least three colors.

As shown inFIG.17B, the image sensor20fincludes four third pixel arrays100c. Each of the third pixel arrays100cincludes one polyhedron structure110and nine photo diodes122(i.e., nine pixels), and each of the third pixel arrays100chas single color. In other words, the polyhedron structure110of each of the third pixel array100coverlaps with nine photo diodes122and one color filter. The four third pixel arrays100cof the image sensor20fcollectively form a RGGB arrangement as shown inFIG.16A. In some other embodiments, the image sensor20fcan have other types of color arrangements such as those arrangements shown inFIGS.16B to16E.

As shown inFIG.17C, the image sensor20gincludes four fourth pixel arrays100d. Each of the fourth pixel arrays100dincludes sixteen photo diodes122, and each of the fourth pixel arrays100dhas single color. In other words, the polyhedron structure110of each of the fourth pixel array100doverlaps with sixteen photo diodes122and color filter. The four fourth pixel arrays100dof the image sensor20gcollectively form a RGGB arrangement as shown inFIG.16A. In some other embodiments, the image sensor20gcan have other types of color arrangements such as those arrangements shown inFIGS.16B to16E.

As shown inFIG.17D, the image sensor20hincludes four sixth pixel arrays100f. Each of the sixth pixel arrays100fis similar to the image sensor20eshown inFIG.17A, and the difference is that each of the sixth pixel arrays100fhas single color. In other words, four polyhedron structures110of each of the sixth pixel arrays100fcollectively overlap with one color filter. That is, an orthogonal projection of more than one polyhedron structure110overlaps with one color filter. The four sixth pixel arrays100fof the image sensor20hcollectively form a RGGB arrangement as shown inFIG.16A. In some other embodiments, the image sensor20hcan have other types of color arrangements such as those shown inFIGS.16B to16E.

Alternatively, the sixth pixel arrays100finFIG.17Dcan be considered as a combination of a single color filter and four pixel arrays, and each of the pixel arrays includes one polyhedron structure110and four photo diodes122. Therefore, at least one of the polyhedron structures of these four pixel arrays overlaps with the same color filter.

FIG.18is an electromagnetic field simulation result.FIG.18represents the electric field distributions on the photo diodes of an image sensor10as shown inFIG.1andFIG.2when the wavelength of an incident light is 450 nm (blue), 550 nm (green), and 650 nm (red), respectively. The image sensor10only has a polyhedron structure110and has no micro lens. The electric field distribution of the image sensor10shows multiple peaks, and positions of those peaks are correlated with the pixel arrangements. That is, energy of the incident light can be divided by the polyhedron structures of the image sensor10based on the pixel arrangement. As such, the energy received by each photo diodes122is even. Therefore, the configuration of the image sensor of the present disclosure can improve the performance of the photo diodes.

FIG.19is a schematic of a pixel array300according to one embodiment of the present disclosure. The pixel array300includes a polyhedron structure310, an under layer340, a photo photoelectric conversion layer320having four photo diodes322, and a color filter330located between the polyhedron structure310and the photo diodes322. The polyhedron structure310is a pentahedron. An incident light travels along a ray direction R. A centroid315aof the polyhedron structure310a, a center335of the color filter330, and a center325of the photo diodes322are arranged along the ray direction R of the incident light. In other words, all layers of the pixel array300are shifted based on a Chief Ray Angle (CRA). As such, the efficiency of the pixel array300can be improved.

FIG.20Ais a schematic of a light distribution on the polyhedron structure310according to one embodiment of the present disclosure. As shown inFIG.20A, a normal N1of the vertex313of the polyhedron structure310points toward a second direction (vertical direction) Y. The incident light L1has a Chief Ray Angle of 30 degrees relative to the vertical direction Y (i.e., a direction of an optical axis). As shown by the range R1and the range R2, the side facet316A (shady side) is less exposed by the incident light, and the side facet316B (bright side) is more exposed by the incident light. As a result, the amount of the light that can be refracted by the side facet316A and the side facet316B is uneven. In other words, energy distribution of the incident light L1after passing through the polyhedron structure310is uneven.

FIG.20Bis a schematic of a light distribution on the polyhedron structure310according to one embodiment of the present disclosure. As shown inFIG.20B, a normal N2of the vertex313aof the polyhedron structure310apoints toward a direction parallel with the ray direction R of the incident light L1. As a result, the range R3and the range R4are equal. Therefore, the side facet316A and the side facet316B of the polyhedron structure310aare equally exposed by the incident light L1, and energy distribution of the incident L1after passing through the polyhedron structure310ais even. In some other embodiments, a normal of the top facet of the polyhedron structure is parallel with the ray direction R. Accordingly, the shift of the normal of the vertex or the top facet of the polyhedron structure based on the ray direction (i.e., CRA) can improve performance of the image sensor.

FIG.21AandFIG.21Bare top views of an image sensor30according to one embodiment of the present disclosure. The image sensor30includes twenty-five photo diodes322arranged as a 5×5 array. Each photo diodes322overlaps with one polyhedron structure310,310a,310b. The polyhedron structures are omitted inFIG.21A. When an incident light travel towards the center C5of the image sensor30. Ray directions R relative to each photo diodes322are represented by arrows. Specifically, the CRA for each photo diodes322is greater when the distance between the center C5and the photo diodes322.

As shown inFIG.21B, all the polyhedron structure310afollow the rules demonstrated inFIG.20B. For example, four polyhedron structures310alocated at the corners of the image sensor30have a CRA of 30 degrees as described inFIG.20B. The vertexes313aof the polyhedron structures310ashift towards the center C5of the image sensor30. The nine polyhedron structures310blocated at the outer part of the image sensor and located between the polyhedron structure310ahave a CRA smaller than 30 degrees. The vertexes313bof the polyhedron structures310bshift towards the center C5. Similarly, the polyhedron structures310clocated at the corners of an inner part of the image sensor30have a smaller CRA, and therefore the shifts of the vertexes313care smaller. The polyhedron structures310dlocated between the polyhedron structures310c, and the shifts of the vertexes313dare smaller than the shifts of the vertexes313c. The polyhedron structure310located at the center C5of the image sensor is substantially the same as the polyhedron structure310as shown inFIG.20A. Accordingly, the further the polyhedron structures away from the center C5, the more the vertexes shift. As such, shifts of the vertexes form a concentric circle. With such design, the efficiency of the image sensor30can be improved.

FIG.22is a schematic of a first pixel array400according to one embodiment of the present embodiment. The first pixel array400includes a polyhedron structure410, a photo photoelectric conversion layer420having four photo diodes422, a color filter430located between the polyhedron structure410and the photo diodes422, and a micro lens460located between the polyhedron structure410and the color filter430. The polyhedron structure410is a pentahedron. The light beams divided by the polyhedron structure410can be focused on the photo diodes422through the micro lens460.

FIG.23is a plot of relation between focusing separation distance and a height H2of polyhedron structure. As shown inFIG.22, the height H2is the distance between the bottom facet412and the vertex413. The curves S1˜S3respectively represents the focusing separation distance when the refractive indexes of the polyhedron structure410are 1.25, 1.35, and 1.45, respectively. The refractive index of the micro lens460is 1.68. Accordingly, when the height H2is fixed, suitable focusing separation distances can be determined by controlling the refractive index of the polyhedron structure410.

FIGS.24A to24Dare illuminance diagrams of the photo diodes422with various height H of the polyhedron structure410. The illuminance diagrams inFIGS.24A to24Dare derived when the height H2(seeFIG.22) of the polyhedron structure410are 0.18 um, 0.28 um, 0.38 um, and 0.48 um, respectively. —Based on those results shown inFIG.23andFIGS.24A to24D, suitable focusing separation distances can be determined by controlling the height H2and the refractive index of the polyhedron structure410.

FIG.25AandFIG.25Bare top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.25A, the image sensor40aincludes sixteen first pixel array400as shown inFIG.22arranged as a 4×4 array. The micro lenses460respectively overlap with the polyhedron structures410. As shown inFIG.25B, the image sensor40bis similar to the image sensor40a, and the difference is that each of the micro lenses460overlap with twenty-five photo diodes422which are arranged as a 5×5 array. In some other embodiments, the configuration of the photo diodes422under each of the micro lenses460can be different, such as a 3×3 array or a 4×4 array.

FIG.26AandFIG.26Bare top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.26A, the image sensor40chas nine micro lenses460, nine polyhedron structures410a, and eighty-one photo diodes422(i.e., eighty-one pixels). The micro lenses460respectively overlap with the polyhedron structures410a. Each of the polyhedron structures410ahas eight side facets416, a square bottom facet412and a circular top facet414that are similar to the polyhedron structure110jshown inFIG.10A. Each of the polyhedron structures410aoverlaps with nine photo diodes422arranged as a 3×3 array. Therefore, a sum of a number of the side facets416and a number of the top facet414of the polyhedron structure410aequals to the number of the photo diodes422.

As shown inFIG.26B, the image sensor40dhas four micro lenses460, four polyhedron structures410b, and sixty-four photo diodes422. The polyhedron structures410bare similar to the polyhedron structures110kshown inFIG.10C. The micro lenses460respectively overlap with the polyhedron structures410b. Each of the polyhedron structures410boverlaps with sixteen photo diodes422arranged as a 4×4 array. Therefore, a number of the side facets416of the polyhedron structure410bequals to the number of the photo diodes422.

In the embodiments shown inFIG.26AandFIG.26B, the polyhedron structure410aand the polyhedron structure410bare prisms. The energy of an incident light can be distributed more uniformly to the one or more pixels underlying the top fact414and the pixels underlying the side facets416.

FIG.27AandFIG.27Bare top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.27A, the image sensor40eincludes fourteen first pixel arrays400A and one second pixel array400B. The first pixel array400A is similar to the pixel array400shown inFIG.22. The second pixel array400B includes one micro lens460aoverlaps with eight photo diodes422arranged as a 4×2 array, and the second pixel array400B has no polyhedron structure. As shown inFIG.27B, the image sensor40fincludes twelve first pixel array400A and one second pixel arrays400B. The second pixel array400B includes one micro lens460aoverlaps with sixteen photo diodes422arranged as a 4×4 array, and the second pixel array400B has no polyhedron structure. The configuration of the image sensor40e,40fcan be utilized for specific functions such as auto focus function.

FIGS.28A to28Care top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.28A, the image sensor40gincludes fourteen first pixel array400A and one second pixel array400B. The first pixel array400A is similar to the pixel array400shown inFIG.22. The second pixel array400B includes one polyhedron structure410c, one micro lens460c, and eight photo diodes422arranged as a 4×2 array. The micro lens460cand the micro lens410have different shapes. A volume of the micro lens460cis greater than a volume of the micro lens460. The polyhedron structure410cand the polyhedron structure410are both pentahedron, and a volume of the polyhedron structure410cis greater than a volume of the polyhedron structure410. In other words, a volume of the polyhedron structure410of the first pixel array400A is different from a volume of the polyhedron structure410cof the second pixel array400B.

As shown inFIG.28B, the image sensor40hincludes twelve first pixel array400A and one second pixel array400B. The second pixel array400B includes one polyhedron structure410d, one micro lens460d, and sixteen photo diodes422arranged as a 4×4 array. A volume of the micro lens460dis greater than a volume of the micro lens460. The top facet414dof the polyhedron structure410dhas a circular shape. In other words, the polyhedron structure410dand the polyhedron structure410have different shapes.

As shown inFIG.28C, the image sensor40iincludes fourteen first pixel array400A and one second pixel array400B. The second pixel array400B has one polyhedron structure410e, one micro lens460e, and eight photo diodes422arranged as a 4×2 array. The polyhedron structure410ehas an elliptical top facet414eand eight side facet416e. The polyhedron structure110nhas an octagonal column shape. In other words, a number of the side facets416(seeFIG.22) of the polyhedron structure410of the first pixel array100A is different from a number of the side facets416eof the polyhedron structure410eof the second pixel array100B.

FIG.29AandFIG.29Bare top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.29A, the image sensor40iincludes twelve first pixel array400A and on second pixel array400B. The first pixel array400A is similar to the pixel array400shown inFIG.22. The second pixel array400B includes four polyhedron structures410, one micro lens460f, and sixteen photo diodes422arranged as a 4×4 array. In other words, a total number of the micro lens460and the micro lens460fis different from a number of the polyhedron structures410.

As shown inFIG.29B, the image sensor40jis similar to the image sensor40i, and the difference is that the second pixel array400B includes one polyhedron410fand four micro lenses460. In other words, a number of the micro lenses460is different from a total number of the polyhedron structures410

FIG.30AandFIG.30Bare top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.30A, the image sensor40kincludes sixty-four polyhedron structures410gand sixteen micro lenses460. Each of the polyhedron structures410goverlaps with one photo diodes422(i.e., one pixel). One micro lens460overlaps with four polyhedron structures410gand four photo diodes422. As shown inFIG.30B, the image sensor40I is similar to the image sensor40k, and the difference is that each of the micro lens460hoverlaps with nine polyhedron structures and nine photo diodes422.

FIGS.31A to31Eare top views of color arrangement of the color filters of the image sensors according to some embodiments of the present disclosure. Reference is made toFIG.22, andFIGS.31A to31E. The image sensors shown inFIGS.31A to31Eall include four polyhedron structures410and four micro lenses460as described inFIG.22. Each of the micro lenses460or the polyhedron structures410overlaps with multiple photo diodes422, and a 2×2 array is demonstrated herein merely as an example.

As shown inFIG.31A, the image sensor50has a RGGB arrangement. That is the image sensor50includes color filters corresponding to red, green, and blue. As shown inFIG.31B, the image sensor50ahas a RGBW arrangement. That is, the image sensor50aincludes color filters corresponding to red, green, blue, and white. As shown inFIG.31C, the image sensor50bhas a CYYM arrangement. That is, the image sensor50bincludes color filters corresponding to cyan, yellow, and magenta. As shown inFIG.31D, the image sensor50chas a RYYB arrangement. That is, the image sensor50cincludes color filters corresponding to red, yellow, and blue. As shown inFIG.31E, the image sensor50dhas a RGBIR arrangement. That is, the image sensor50dincludes color filters corresponding to red, green, blue, and infrared.

FIGS.32A to32Dare top views of image sensors according to some embodiments of the present disclosure. As shown inFIG.32A, the image sensor50eincludes four fifth pixel arrays400e. Each of the fifth pixel arrays400eincludes four pixels and has a RGGB arrangement. In other words, the polyhedron structure410of each of the fifth pixel array400eoverlaps with four photo diodes122and four color filters including different colors (red, green, and blue). That is, an orthogonal projection of each of the polyhedron structure410overlaps with the color filters having at least three colors.

As shown inFIG.32B, the image sensor50fincludes four third pixel arrays400c. Each of the third pixel arrays400cincludes nine pixels and has single color. In other words, the polyhedron structure410of each of the third pixel arrays400cis overlapped with nine photo diodes422and one color filter. The four third pixels arrays400cof the image sensor50fcollectively form a RGGB arrangement as shown inFIG.31A. In some other embodiments, the image sensor50fcan have other types of color arrangements such as those shown inFIGS.31B to31E.

As shown inFIG.32C, the image sensor50gincludes four fourth pixel arrays400d. Each of the fourth pixel arrays400dincludes sixteen pixels and has single color. In other words, the polyhedron structure410of each of the fourth pixel arrays400doverlaps with sixteen photo diodes422and one color filter. The four fourth pixels arrays400dof the image sensor50gcollectively form a RGGB arrangement as shown inFIG.31A. In some other embodiments, the image sensor50gcan have other types of color arrangements such as those shown inFIGS.31B to31E.

As shown inFIG.32D, the image sensor50hincludes four sixth pixel arrays400f. Each of the sixth pixel arrays400fis similar to the image sensor50eshown inFIG.32A, and the difference is that each of the sixth pixel arrays400fhas single color. In other words, four polyhedron structures410of each of the sixth pixel arrays100foverlap with one color filter. That is, an orthogonal projection of more than one polyhedron structure410overlaps with one color filter. The four sixth pixels arrays400fof the image sensor50hcollectively form a RGGB arrangement as shown inFIG.31A. In some other embodiments, the image sensor50hcan have other types of color arrangements such as those shown inFIGS.31B to31E.

FIG.33Ais a partial top view of an image sensor according to one embodiment of the present disclosure.FIG.33Bis a cross-sectional view taken along line33B-33B inFIG.33A. As shown inFIG.34A, a polyhedron structure410hincludes edges417hformed between adjacent two of the side facets416h. The photo diodes422are arranged along a first direction X (horizontal) and a second direction Y (vertical) perpendicular to the first direction X. Therefore, orthogonal projections of the edges417hextend along the first direction X or the second direction Y.

Reference is made toFIG.22andFIG.25A. Orthogonal projections of the edges417of the polyhedron structure410extend along the directions different from the first direction X or the second direction Y. In the embodiment inFIG.22, the orthogonal projections of the edges417extend along diagonal directions. Therefore, comparing with the polyhedron structure410as shown inFIG.22, the polyhedron structure410hshown inFIG.33Aare rotated 90 degrees with a rotation axis parallel with the third direction Z. With such configuration, the side facets416face the photo diodes422so as to improve the focusing ability. As shown inFIG.34B, two polyhedron structure410hare connected together, and there is a side wall419hlocated between adjacent two polyhedron structures410h.

FIG.33CandFIG.33Dare top view of image sensors according to some embodiments of the present disclosure. As shown inFIG.33C, the image sensor60includes sixteen polyhedron structures410hand sixteen micro lenses460. Each of the polyhedron structure410and the micro lens460overlaps with four photo diodes422. The edges417are extend along the first direction X and the second direction Y, and the vertexes413overlaps the centers of the micro lenses460. The side wall419hoverlaps with an interface between two micro lens460. As shown inFIG.33D, the image sensor60ais similar to the image sensor60, and the difference is that each of the micro lenses460overlaps with twenty-five photo diodes422. The image sensor60acan has similar advantages as those of the image sensor60, and the description is not repeated hereinafter.

FIG.34is a schematic of optical path when an incident light traveling through the polyhedron structure410i. In the present embodiment, the vertex413iof the polyhedron structure410iis shifted. For example, an orthogonal projection of the vertex413iis located between the first pixel array400A and the second pixel array400B. With such configuration, an incident light L1can be divided into light beams L2, L3focused in the photo diodes422to improve performance of the photo diodes422. Therefore, the first pixel array400A and the second pixel array400B of the present embodiment can have the similar advantages as those of the pixel array400shown inFIG.22, and the description is not repeated hereinafter.

FIG.35Ais a partial top view of an image sensor according to one embodiment of the present disclosure.FIG.35BandFIG.35Care top view of image sensors according to some embodiments of the present disclosure. As shown inFIG.35A, a polyhedron structure410iincludes edges417iformed between adjacent two of the side facets416i. The polyhedron structure410ipartially overlaps with four micro lenses460. A vertex413iof the polyhedron structure410iis located at the position surrounded by these four adjacent micro lenses460.

As shown inFIG.35B, the image sensor60bincludes sixteen polyhedron structures410iand sixteen micro lenses460. Each of the polyhedron structure410iand the micro lens460overlaps with four photo diodes422. The edges417iare extend along the first direction X and the second direction Y, and the vertexes413iare located at the position surrounded by four adjacent micro lenses460. As shown inFIG.35C, the image sensor60cis similar to the image sensor60b, and the difference is that each of the micro lenses460ioverlaps with nine photo diodes422. The image sensor60ccan has similar advantages as those of the image sensor60b, and the description is not repeated hereinafter.

FIGS.36A to36Care cross-sectional view of pixel arrays according to some embodiments of the present disclosure. As shown inFIG.36A, the pixel array70includes a color filter430, a micro lens460, and a polyhedron structure410. The polyhedron structure410is directly formed on the micro lens460, and there is no other layer formed on the polyhedron structure410. Under this condition, a refractive index of the micro lens460is greater than an refractive index of the polyhedron structure410, and the refractive index of the polyhedron structure410is greater than 1.1 (i.e., the refractive index of air).

As shown inFIG.36B, the pixel array70ais similar to the pixel array70, and the difference is that the pixel array70afurther includes an index matching layer470located between the micro lens460and the polyhedron structure410. Under this condition, the refractive index of the index matching layer is smaller than the refractive index of the micro lens460and is greater than the refractive index of the polyhedron structure410. As such, light transmission efficiency and performance of the photo diodes422can be improved.

As shown inFIG.36C, the pixel array70bis similar to the pixel array70a, and the difference is that the pixel array70bfurther includes a first antireflection layer480, a second antireflection layer482, and an index changing layer490. The first antireflection layer480is coated on the polyhedron structure410. The second antireflection layer482is located between the polyhedron structure410and the index changing layer490. The index changing layer490is located between the second antireflection layer482and the micro lens460. Under this condition, the refractive index of the polyhedron structure410is greater than the refractive index of the index changing layer490and is smaller than or equal to the refractive index of the micro lens460. As such, light transmission efficiency and performance of the photo diodes422can be improved.

FIG.37is an electromagnetic field simulation result. Data in the first row represent the electric field distributions on the photo diodes of an image sensor having the pixel array400as shown inFIG.22when the wavelength of an incident light is 450 nm (blue), 550 nm (green), and 650 nm (red), respectively. Data in the second row represent the electric field distributions on the photo diodes of an image sensor having the pixel array as shown inFIG.34. As shown inFIG.37, the electric field distribution of the image sensor show multiple peaks, and positions of those peaks are correlated with the pixel arrangements. That is, energy of the incident light can be divided by the polyhedron structure of the image sensor based on the pixel arrangement. As such, the energy received by each photo diodes422is even. In addition, even there is a shift between the polyhedron structure and the micro lens or the photo diodes, performance of the photo diodes can still be improved.

In summary, the polyhedron structure is configured to divide an incident light into multiple light beams towards the photo diodes. In addition, a number of the light beam can be determined by a number of the side facets of the polyhedron structure. A position of the focus of the light beam can be determined by the area of the top facet of the polyhedron structure, the height of the polyhedron, or the refractive index of the polyhedron structure. As such, focuses of the light beams are positioned more correlated with positions of photo diodes. Therefore, performance of the photo diodes can be improved.

Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.