Solid-state imaging device

Abstract

A solid-state imaging device includes a plurality of photoelectric conversion elements arranged in a pixel array, and a color filter layer having a plurality of color filter segments above the photoelectric conversion elements, each color filter segment being disposed in an individual pixel of the pixel array. The solid-state imaging device also includes a light waveguide layer above the color filter layer, the light waveguide layer including a waveguide separation grid and a waveguide material in voids of the waveguide separation grid, a refractive index of the waveguide material being higher than a refractive index of the waveguide separation grid, and the waveguide material being capable of providing a same refractive index for each pixel of the pixel array.

Description

[0001] This application is a divisional application of the invention patent application filed by Caiyu Technology Co., Ltd. on June 3, 2019, with application number 2019104764483 and invention title "Solid-State Imaging Device". Technical Field

[0002] This invention relates to imaging apparatus, and more particularly to a solid-state imaging apparatus having a top optical waveguide layer above a color filter layer. Background Technology

[0003] Image sensors, such as charge-coupled device (CCD) image sensors and complementary metal-oxide semiconductor (CMOS) image sensors, are widely used in various imaging devices, such as digital still cameras, digital camcorders, and similar devices. An image sensor has multiple pixels arranged in a pixel array, each pixel having a photoelectric converter, such as a photodiode, formed in a semiconductor substrate, such as a silicon chip. The photodiode generates charge by photoelectric conversion of incident light incident on the image sensor. The corresponding charge of the photoelectrons generated in the photodiode can be transmitted and amplified by CCD-type or CMOS-type readout circuitry to obtain an imaging signal.

[0004] Some imaging devices use phase-detection sensors to perform autofocus. Phase-detection on the sensor operates by inserting phase-detection autofocus (PDAF) pixels between the imaging pixels. These PDAF pixels are typically arranged in a sparse pattern repeating between the left and right pixels. This image sensor can detect the phase difference between the signals generated by the different phase-detection pixels, such as the phase difference between a left pixel and its neighboring right pixel. Generally, phase-detection autofocus operates faster than contrast-based autofocus.

[0005] In recent years, in order to increase the number of pixels to provide high-resolution images, the trend in image sensors, especially CMOS image sensors, has been to reduce pixel size. However, as pixel size continues to decrease, various challenges remain in the design and manufacturing of image sensors. Summary of the Invention

[0006] In traditional CMOS image sensors (CIS), crosstalk is prone to occur at the corners of the image sensor because incident light strikes the edges of the pixel array at an angle. Without a good algorithm, crosstalk can lead to image detection failure and autofocus errors. As pixel sizes continue to decrease, the crosstalk problem worsens.

[0007] According to an embodiment of the present invention, a top-guide structure is provided on the color filter layer to overcome the crosstalk interference problem of solid-state imaging devices. This top-guide structure is an optical waveguide layer, which includes a low-refractive-index grid and a high-refractive-index material in the gaps of the low-refractive-index grid. Furthermore, the top-guide structure of the present invention can enhance the phase-detection autofocus (PDAF) function of the solid-state imaging device.

[0008] In some embodiments, a solid-state imaging device is provided. This solid-state imaging device includes a plurality of photoelectric conversion elements arranged in a pixel array. The solid-state imaging device also includes a color filter layer having a plurality of color filter segments located above the photoelectric conversion elements, each color filter segment being disposed in an individual pixel of the pixel array. The solid-state imaging device further includes an optical waveguide layer above the color filter layer, the optical waveguide layer comprising a waveguide partition grid and waveguide material in the gaps of the waveguide partition grid, the waveguide material having a refractive index higher than the refractive index of the waveguide partition grid, the waveguide material providing the same refractive index to each pixel of the pixel array. Attached Figure Description

[0009] To facilitate understanding of the embodiments of the present invention, a detailed description is provided below in conjunction with the accompanying drawings. It should be noted that, according to industry standard examples, the components may not be drawn to scale. In fact, for clarity of discussion, the dimensions of each component may be arbitrarily enlarged or reduced.

[0010] Figure 1 This is a cross-sectional schematic diagram of a solid-state imaging device according to some embodiments of the present invention.

[0011] Figures 2A to 2C To form according to some embodiments of the present invention Figure 1 Schematic cross-sectional views of the various stages of a demonstration method for a solid-state imaging device with an optical waveguide layer.

[0012] Figure 3 This is a cross-sectional schematic diagram of a solid-state imaging device according to some embodiments of the present invention.

[0013] Figures 4A to 4C To form according to some embodiments of the present invention Figure 3 Schematic cross-sectional views of the various stages of a demonstration method for a solid-state imaging device with an optical waveguide layer.

[0014] Figure 5A This is a planar schematic diagram of a portion of the pixel array of a solid-state imaging device having phase detection autofocus (PDAF) pixels, according to some embodiments of the present invention.

[0015] Figure 5B According to some embodiments of the present invention, along Figure 5A A cross-sectional schematic diagram of a solid-state imaging device with phase detection autofocus (PDAF) pixels.

[0016] Figure 6A This is a cross-sectional schematic diagram of a portion of a solid-state imaging device having normal pixels located in the central region of a pixel array, according to some embodiments of the present invention.

[0017] Figure 6B This is a cross-sectional schematic diagram of a portion of a solid-state imaging device having regular pixels located at the edge of a pixel array, according to some embodiments of the present invention.

[0018] Figure 7A This is a cross-sectional schematic diagram of a portion of a solid-state imaging device having phase detection autofocus (PDAF) pixels located in the central region of a pixel array, according to some embodiments of the present invention.

[0019] Figure 7B This is a cross-sectional schematic diagram of a portion of a solid-state imaging device having phase detection autofocus (PDAF) pixels located at the edge of a pixel array, according to some embodiments of the present invention.

[0020] Figure 8 This is a cross-sectional schematic diagram of a solid-state imaging device having a top-guide structure, according to some embodiments of the present invention.

[0021] Figure 9 This is a cross-sectional schematic diagram of a solid-state imaging device with a top guide structure, according to some other embodiments of the present invention.

[0022] Figure 10 This is a cross-sectional schematic diagram of a solid-state imaging device with a top-guided structure, according to some other embodiments of the present invention.

[0023] Figure 11 This is a cross-sectional schematic diagram of a solid-state imaging device with a top-guided structure, according to some other embodiments of the present invention.

[0024] Explanation of reference numerals in the attached figures: 100, 200, 200C, 200E, 300, 300C, 300E, 400, 500, 600, 700 ~ solid-state imaging devices; 101 ~ Semiconductor substrate; 101B – Backside surface; 101F – Front surface; 103 ~ Photoelectric conversion element (photodiode); 105 – Wiring layer; 107~ High dielectric constant (high k) films; 109 ~ Buffer layer; 110 ~ Photoelectric conversion structure; 111 ~ Light-shielding layer; 113 ~ Dividing grid; 113A, 123A, 133A – Waveguide partition grid; 113B – Color filter dividing grid; 113CL, 123CL – Center lines of individual separators; 114, 114' ~ gap; 115~Color filter section; 120 ~ Color filter layer; 121, 131 ~ Waveguide materials; 121' ~ Transparent dielectric material; 122 ~ Opening; 123B, 133B – Anti-reflective coating; 123LS-C, 123LS-E ~ left sidewall of the separator; 125~Planar layer; 127 – Protective layer; 130, 140 ~ Optical waveguide layer; 150° - Incident light; 150R ~ reflected light; 150T ~ Transmitted light; 150E ~ oblique incident light; P, P1, P2, P3 ~ pixels; W, W1, W2, W3 ~ width; T ~ thickness; PW ~ pixel size; U ~ Color filter unit; PDAF – Phase Detection Autofocus Pixel; θ ~ angle; X ~ Distance; ΔX ~ displacement distance; D – Direction. Detailed Implementation

[0025] In a solid-state imaging device, incident light strikes the edge of a pixel array at an angle greater than the normal angle at which the incident light strikes the central region of the pixel array. This angle is determined by the normal angle deviating from the light-receiving surface of the solid-state imaging device. For example, the angle of incident light striking the edge of the pixel array is typically between approximately + / -20 degrees and approximately + / -40 degrees, while the normal angle at which the incident light strikes the central region of the pixel array is approximately 0 degrees.

[0026] Based on the direction of light incident on the light-receiving unit, solid-state imaging devices can be broadly classified into two types: front-side illuminated (FSI) imaging devices, which receive light incident on the front side of the semiconductor substrate, where a wiring layer for the readout circuit is formed; and back-side illuminated (BSI) imaging devices, which receive light incident on the back side of the semiconductor substrate, where no wiring layer is formed. For color image imaging, color filters are provided in both FSI and BSI imaging devices. Furthermore, FSI and BSI imaging devices typically have a light-shielding mesh structure to block light between pixels and prevent color mixing.

[0027] Figure 1 A cross-sectional view of a solid-state imaging device 100 according to some embodiments of the present invention is shown. The solid-state imaging device 100 may be formed from a complementary metal-oxide-semiconductor (CMOS) image sensor or a charge-coupled device (CCD) image sensor. The solid-state imaging device 100 includes a semiconductor substrate 101, such as a wafer or a chip. The semiconductor substrate 101 has a front surface 101F and a back surface 101B opposite to the front surface 101F. A plurality of photoelectric conversion elements 103, such as photodiodes, are formed in the semiconductor substrate 101, and the photoelectric conversion elements 103 may also be referred to as photodiodes 103. The solid-state imaging device 100 has a plurality of pixels P arranged in a pixel array, and each photodiode 103 is disposed in an individual pixel of the pixel array. The photodiodes 103 in the semiconductor substrate 101 are isolated from each other via an isolation structure (not shown), such as a shallow trench isolation (STI) region or a deep trench isolation region, which is formed by etching trenches in the semiconductor substrate 101 and filling the trenches with an insulating or dielectric material to form the isolation structure. Although the accompanying drawings of the solid-state imaging device of the embodiment show only a few pixels, the solid-state imaging device in reality has millions or more pixels in the pixel array.

[0028] In some embodiments, a photodiode 103 is formed on the back surface 101B of a semiconductor substrate 101, and a wiring layer 105 is formed on the front surface 101F of the semiconductor substrate 101. The wiring layer 105 is an interconnect structure containing multiple wires and vias buried in multiple dielectric layers, and the wiring layer 105 may also include various circuits required by the solid-state imaging device 100. In some embodiments, such as Figure 1 The solid-state imaging device 100 shown has incident light 150 illuminating the side of the back surface 101B and being received by the photodiode 103, therefore... Figure 1 The solid-state imaging device 100 shown may be referred to as a back-illuminated (BSI) imaging device. In some other embodiments, the solid-state imaging device may be a front-illuminated (FSI) imaging device. For an FSI imaging device, Figure 1 The semiconductor substrate 101 and wiring layer 105 shown are flipped vertically. In the FSI imaging apparatus, incident light 150 illuminates the side of the front surface 101F, passes through the wiring layer 105, and is then received by a photodiode 103 formed on the back surface 101B of the semiconductor substrate 101. In the FSI imaging apparatus, the path distance of the incident light through the various layers to reach the photodiode is greater than that in the BSI imaging apparatus.

[0029] like Figure 1 As shown, in some embodiments, the solid-state imaging device 100 further includes a high-k dielectric constant (high-k) film 107 formed on the back surface 101B of the semiconductor substrate 101 and covering the photoelectric conversion element 103. The high-k film 107 may be made of hafnium oxide (HfO2), hafnium tantalum oxide (HfTaO), hafnium titanium oxide (HfTiO), hafnium zirconium oxide (HfZrO), tantalum pentoxide (Ta2O5), or other suitable high-k dielectric materials, and may be formed using a deposition process. The deposition process may be, for example, chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), atomic layer deposition (ALD), or other deposition techniques. In some embodiments, the high-k film 107 has a high refractive index and light absorption capacity.

[0030] like Figure 1As shown, in some embodiments, the solid-state imaging device 100 further includes a buffer layer 109 formed on a high-k film 107. The buffer layer 109 may be made of silicon oxide, silicon nitride, silicon oxynitride, or other suitable insulating materials, and may be formed using a deposition process. Deposition processes include, for example, spin coating, CVD, flowable CVD (FCVD), PECVD, physical vapor deposition (PVD), or other deposition techniques. In this description, for simplicity, the semiconductor substrate 101, the photoelectric conversion element (or photodiode) 103, the wiring layer 105, the high-k film 107, and the buffer layer 109 may be collectively referred to as the photoelectric conversion structure 110.

[0031] Furthermore, according to some embodiments, such as Figure 1 As shown, the solid-state imaging device 100 also includes a light-shielding layer 111 formed on the buffer layer 109. The light-shielding layer 111 includes a plurality of light-shielding spacers disposed between the pixels of the solid-state imaging device 100. From the top view, these light-shielding spacers of the light-shielding layer 111 form a grid structure. In some examples, the light-shielding layer 111 is made of metal and may be referred to as a metal grid structure.

[0032] like Figure 1 As shown, in some embodiments, the solid-state imaging device 100 further includes a color filter separator grid 113B formed on a light-shielding separator of the light-shielding layer 111, and the color filter separator grid 113B covering the light-shielding separator. The color filter separator grid 113B is made of a transparent dielectric material having a low refractive index from about 1.0 to about 1.99. Furthermore, a plurality of color filter segments 115 are each disposed in the gaps of the color filter separator grid 113B, the refractive index of the color filter separator grid 113B being lower than the refractive index of the color filter segments 115, each color filter segment 115 corresponding to an individual photoelectric conversion element 103 in a pixel P. In some embodiments, the color filter segments 115 include red (R), green (G), and blue (B) color filter segments, these different colored color filter segments 115 being arranged in a suitable manner in the pixel array. Figure 1The four color filter segments 115 shown are, for example, arranged in the order of G, G, R, and R. In some other embodiments, the color filter segments 115 may also include white (W) or other color filter segments, which are arranged in a suitable manner together with the R, G, and B color filter segments in the pixel array. In some embodiments, the top surface of the color filter segment 115 may be flush with the top surface of the color filter separator grid 113B. For simplicity, the light-shielding layer 111, the color filter separator grid 113B, and the color filter segments 115 described above may be collectively referred to as color filter layer 120.

[0033] According to an embodiment of the invention, a top guiding structure, such as an optical waveguide layer 130, is formed on a color filter layer 120. The optical waveguide layer 130 includes a waveguide partition grid 113A on the color filter partition grid 113B, and waveguide material 121 in the voids of the waveguide partition grid 113A, the top surface of which may be flush with the top surface of the waveguide partition grid 113A. In some embodiments, the waveguide partition grid 113A is made of a transparent dielectric material having a low refractive index of about 1.0 to about 1.99. The waveguide material 121 is made of another transparent dielectric material with a higher refractive index than that of the waveguide partition grid 113A. In some embodiments, the refractive index of the waveguide material 121 is about 1.1 to about 2.0.

[0034] Typically, waves in open space are spherical waves and propagate in all directions. The power of a wave decreases with increasing distance R from its source, and this power is inversely proportional to the square of the distance (known as the inverse square law). For example, when light waves propagate through the microlens structure of an image sensor, the energy of the light decreases with increasing distance R from the source, and the energy of the light is inversely proportional to the square of the distance. However, waveguide structures can confine waves to propagate in one dimension, so under ideal conditions, waves do not lose power when propagating through a waveguide. This is due to total internal reflection occurring at the walls of the waveguide structure, thus confining the wave within the waveguide.

[0035] Optical waveguide structures are structures that guide electromagnetic waves, such as visible light, in the spectrum, minimizing energy loss by confining the propagation of light to one or two dimensions. In some embodiments of the present invention, the top guiding structure is an optical waveguide layer formed above the color filter layer of a solid-state imaging device. Without the physical constraint of an optical waveguide layer, the amplitude of the light wave decreases according to the inverse square law when it propagates into three-dimensional space.

[0036] Waveguides used at optical frequencies are typically dielectric waveguide structures, in which a dielectric material with high permittivity or dielectric constant is surrounded by a material with lower permittivity or dielectric constant; that is, a dielectric material with high refractive index is surrounded by a material with low refractive index. This structure can guide light waves through total internal reflection. An example of an optical waveguide structure is an optical fiber.

[0037] In an embodiment of the present invention, the refractive index of the waveguide material 121 is higher than that of the waveguide partition grid 113A, therefore, the oblique incident light 150 illuminating the solid-state imaging device 100 can be guided by total internal reflection, such as... Figure 1 As shown. Therefore, the optical waveguide layer 130 of this embodiment of the invention can confine the oblique incident light 150 in one dimension, propagating towards the color filter segment 115. Due to total internal reflection at the walls of the waveguide partition grid 113A, the light is confined within the waveguide material 121 of the optical waveguide layer 130, so that the incident light 150 can propagate to the color filter segment 115 with no power loss or only slight power loss, thereby improving the pixel sensitivity of the solid-state imaging device.

[0038] Furthermore, according to embodiments of the present invention, multiple portions of the waveguide material 121 at different pixels of the color filter segment 115 having the same or different colors are made of the same material. Therefore, the optical waveguide layer 130 can provide an equivalent refractive index at different pixels of the same or different colors. Figure 1 As shown, the obliquely incident light 150 illuminating the waveguide partition grid 113A is reflected and transmitted, splitting into reflected light 150R and transmitted light 150T. The reflected light 150R and transmitted light 150T pass through the same waveguide material 121 at different pixels, ensuring that they have the same energy to enter the color filter segments 115 at different pixels. Therefore, the optical waveguide layer 130 can make the energy of the reflected light 150R and transmitted light 150T more consistent at adjacent pixels, thereby overcoming the crosstalk interference problem at the corners of the solid-state imaging device according to an embodiment of the invention.

[0039] When the solid-state imaging device does not have the optical waveguide layer of this embodiment above the color filter layer, the obliquely incident light will directly illuminate the color filter grid and be reflected and transmitted, splitting into reflected light and transmitted light. When this reflected light and transmitted light enter color filter segments with different colors at adjacent pixels, the reflected light and transmitted light will have different energies. Furthermore, the different energies of this reflected light and transmitted light will produce different signal intensities at adjacent pixels with the same color. This phenomenon is called channel separation, which leads to a deterioration in image detection performance.

[0040] As a result of measuring sensitivity at different adjacent pixels of the same color, in a solid-state imaging device having an optical waveguide layer according to an embodiment of the present invention, the sensitivity (normalized sensitivity) difference at the green (G) pixel is approximately 2.7%, the sensitivity difference at the red (R) pixel is approximately 1.4%, and the sensitivity difference at the blue (B) pixel is approximately 1.6%. However, in a solid-state imaging device without an optical waveguide layer according to an embodiment of the present invention, the sensitivity (normalized sensitivity) difference at the G pixel is approximately 4.9%, the sensitivity difference at the R pixel is approximately 1.5%, and the sensitivity difference at the B pixel is approximately 4.4%. These results demonstrate that a solid-state imaging device having an optical waveguide layer according to an embodiment of the present invention can achieve more consistent sensitivity at different adjacent pixels of the same color. Therefore, the optical waveguide layer according to an embodiment of the present invention can overcome the channel separation problem and improve the image detection performance of a solid-state imaging device.

[0041] In some embodiments, the waveguide separator grid 113A and the color filter separator grid 113B are made of the same material. Alternatively, the waveguide separator grid 113A and the color filter separator grid 113B may be manufactured together using the same process steps, such as deposition and etching. In some other embodiments, the waveguide separator grid 113A and the color filter separator grid 113B are made of different materials and are manufactured separately using different process steps.

[0042] Figures 2A to 2C This illustrates some embodiments of the invention, forming a... Figure 1 Cross-sectional views of the structure at various stages of the demonstration method of the solid-state imaging device 100 with optical waveguide layer 130. (See attached diagram.) Figure 2AAs shown, firstly, a light-shielding layer 111 is formed on the buffer layer 109 of the photoelectric conversion structure 110. A metal layer can be deposited on the buffer layer 109, and then the metal layer can be patterned using photolithography and etching processes to form a grid structure composed of multiple light-shielding separators to form the light-shielding layer 111. Next, a separator grid 113 is formed on the buffer layer 109, and the separator grid 113 covers the light-shielding layer 111. A transparent dielectric material layer can be deposited first, and then the transparent dielectric material layer can be patterned using photolithography and etching processes to form a separator grid 113 composed of multiple separators. In some examples, the transparent dielectric material layer has a refractive index of about 1.0 to about 1.99. There are multiple gaps 114 between the separators of the separator grid 113, and each gap 114 corresponds to an individual pixel.

[0043] Then, the gaps 114 of the dividing grid 113 are filled with color filter segments 115, as shown. Figure 2B As shown. The lower portion of the dividing grid 113 surrounding the color filter segment 115 is called the color filter dividing grid 113B. The higher portion of the dividing grid 113 not surrounding the color filter segment 115 serves as the waveguide dividing grid 113A, with multiple gaps 114' between the dividers of the waveguide dividing grid 113A.

[0044] Next, refer to Figure 2C The voids 114' of the waveguide separator grid 113A are filled with a transparent dielectric material 121' using a deposition or coating process. In some examples, the transparent dielectric material 121' has a refractive index of about 1.1 to about 2.0, which is higher than the refractive index of the separator grid 113. Figure 2A In some cases, after a deposition or coating process, a transparent dielectric material 121' covers the top surface of the waveguide partition grid 113A, such as... Figure 2C As shown. Subsequently, excess portions of the transparent dielectric material 121' can be removed using planarization processes, such as chemical mechanical polishing (CMP), to form a shape as shown. Figure 1 The waveguide material 121 is shown. After the planarization process, the top surface of the waveguide material 121 is flush with the top surface of the waveguide partition grid 113A.

[0045] Figure 3A cross-sectional view of a solid-state imaging device 200 according to some embodiments of the present invention is shown. The solid-state imaging device 200 has an optical waveguide layer 130 above a color filter layer 120. The color filter layer 120 includes a light-shielding layer 111, a color filter partition grid 113B on and covering the light-shielding layer 111, and color filter segments 115 in the gaps of the color filter partition grid 113B. The color filter segments 115 and the color filter partition grid 113B have coplanar top surfaces.

[0046] The optical waveguide layer 130 includes a waveguide material 121, a waveguide partition grid 123A, and an anti-reflection film 123B. From a top view, the waveguide material 121 is located within the voids of the waveguide partition grid 123A. The waveguide material 121 and the waveguide partition grid 123A have a coplanar top surface, and the anti-reflection film 123B is also located on this coplanar top surface. In some embodiments, the waveguide partition grid 123A and the anti-reflection film 123B are made of the same material and formed together in the same process step. Alternatively, the waveguide partition grid 123A and the color filter partition grid 113B are manufactured separately in different process steps. In some embodiments, such as Figure 3 As shown, waveguide partition grid 123A is in direct contact with color filter partition grid 113B. According to some embodiments of the invention, the refractive index of waveguide material 121 is higher than that of waveguide partition grid 123A and antireflective film 123B. Furthermore, in some examples, the thickness T of waveguide material 121 is from about 0.2 μm to about 1.5 μm. Additionally, the thickness T can also range from about 0.2 μm to about 0.7 μm. The waveguide material 121 in a single individual pixel has a width W, and this individual pixel has a pixel size PW in width. In some examples, the ratio of the width W of waveguide material 121 to the pixel size PW of the pixel is from about 0.15 to about 0.95.

[0047] According to an embodiment of the present invention, Figure 3 The optical waveguide layer 130 can guide the oblique incident light 150 onto the solid-state imaging device 200 through total internal reflection in the waveguide material 121, such as... Figure 3 As shown. Therefore, the optical waveguide layer 130 can confine the obliquely incident light 150 in one dimension and propagate it toward the color filter segment 115. Due to total internal reflection at the walls of the waveguide partition grid 123A, the light is confined within the waveguide material 121 of the optical waveguide layer 130, and there is no power loss or only a slight power loss when the incident light 150 propagates to the color filter segment 115.

[0048] In addition, Figure 3In this embodiment, multiple portions of the waveguide material 121 at different pixels having the same or different colors are made of the same material. Therefore, the optical waveguide layer 130 can provide an equivalent refractive index at different pixels having the same or different colors. Figure 3 As shown, the obliquely incident light 150 illuminating the waveguide partition grid 123A is reflected and transmitted, splitting into reflected light 150R and transmitted light 150T. The reflected light 150R and transmitted light 150T pass through the same waveguide material 121 at different pixels, ensuring they have the same energy to enter the color filter segments 115 at different pixels. Therefore, the optical waveguide layer 130 makes the energy of the reflected light 150R and transmitted light 150T more consistent at different pixels, thereby overcoming the crosstalk interference problem at the corners of the solid-state imaging device. Furthermore, the optical waveguide layer 130 can also avoid the aforementioned channel separation, thereby improving the image detection effect of the solid-state imaging device according to this embodiment of the invention.

[0049] Figures 4A to 4C This illustrates some embodiments of the invention, forming a... Figure 3 Cross-sectional views of the structure at various stages of the demonstration method of the solid-state imaging device 200 with optical waveguide layer 130. (See attached diagram.) Figure 4A As shown, firstly, a light-shielding layer 111 is formed on the buffer layer 109 of the photoelectric conversion structure 110. Next, a color filter separator grid 113B is formed on the buffer layer 109 and covers the light-shielding layer 111. The materials and processes used to form the light-shielding layer 111 and the color filter separator grid 113B can be the same as those described above. Figure 2A The materials and processes described are the same or similar. Then, a deposition or coating process is used to fill the voids in the color filter separator grid 113B with the color filter segment 115. Afterwards, a planarization process, such as CMP, can be performed on the deposited or coated material of the color filter segment 115, such that the color filter segment 115 and the color filter separator grid 113B have coplanar top surfaces to form a shape as shown in the image. Figure 4A The color filter layer 120 shown.

[0050] Next, as Figure 4B As shown, a transparent dielectric material 121' is deposited on the color filter layer 120. In some examples, the transparent dielectric material 121' has a refractive index of about 1.1 to about 2.0. Then, referring to... Figure 4C The transparent dielectric material 121' is patterned to form multiple openings 122, the positions of which are aligned with the color filter dividing grid 113B. The transparent dielectric material 121' can be patterned using photolithography and etching processes, with the remaining portion of the transparent dielectric material 121' between the openings 122 serving as... Figure 3The waveguide material 121 of the optical waveguide layer 130 shown is then deposited or coated on the waveguide material 121 and the opening 122 is filled, forming a portion of the transparent dielectric material in the opening 122. Figure 3 The waveguide partition grid 123A of the optical waveguide layer 130 shown is formed, and a portion of the transparent dielectric material is formed on the waveguide material 121 and the waveguide partition grid 123A. Figure 3 The waveguide layer 130 shown has an anti-reflective film 123B. In some embodiments, the refractive index of the transparent dielectric material of the anti-reflective film 123B and the waveguide separator grid 123A is lower than the refractive index of the waveguide material 121.

[0051] Figure 5A The diagram illustrates a plan view of a portion of a pixel array in a solid-state imaging device 300 having phase-detection autofocus (PDAF) pixels, according to some embodiments of the invention. In the solid-state imaging device 300, each pixel in the pixel array has a respective color filter segment 115. In some cases, a color filter unit U consists of four color filter segments 115 having the same color. Multiple color filter units U of different colors, such as R, G, and B, are arranged in a suitable configuration within the pixel array. In the normal pixels P of the solid-state imaging device 300 for imaging functions, the color filter segments 115 are separated from each other by a color filter separator grid 113B. In the PDAF pixels of the solid-state imaging device 300 for PDAF functions, for example, four color filter segments 115 having the same color G are in contact with each other and surrounded by a color filter separator grid 113B, separated by color filter segments 115 in adjacent normal pixels. Additionally, the waveguide material 121 disposed on the color filter segment 115 at the regular pixel can be separated by a waveguide separator grid 123A. In some embodiments, the waveguide separator grid 123A is disposed above the color filter separator grid 113B and can be aligned with the color filter separator grid 113B. Furthermore, the waveguide material 121 disposed on the color filter segment 115 at the PDAF pixel is connected together and surrounded by the waveguide separator grid 123A to separate it from the waveguide material 121 in the adjacent regular pixel. The PDAF pixel can be arranged at any suitable position in the pixel array and is arranged together with the regular pixels in the pixel array. The position of the PDAF pixel can be random or regular, depending on the design requirements of the solid-state imaging device.

[0052] Figure 5B Some embodiments of the invention are shown, along Figure 5A The image shows a cross-sectional view of a solid-state imaging device 300 with PDAF pixels, as shown in line BB. Apart from the PDAF pixels, the structure of the solid-state imaging device 300 is similar to... Figure 3 The structure of the solid-state imaging device 200 in the image. A PDAF pixel is composed of multiple pixels; for example, a PDAF pixel can be composed of four pixels, such as... Figure 5A As shown. The PDAF pixel has multiple photoelectric conversion elements 103 for PDAF function. According to an embodiment of the invention, obliquely incident light 150 entering the PDAF pixel is refracted at an angle θ by the waveguide material 121 of the optical waveguide layer 130, and the incident light travels a distance X in the waveguide material 121, in this example the waveguide material 121 has a thickness T, and the distance X is equal to T. tanθ.

[0053] The optical waveguide layer 130 of this embodiment can enhance the PDAF function of a solid-state imaging device. According to the sensitivity measurements at different pixels of the PDAF pixel in a solid-state imaging device having the optical waveguide layer of this embodiment, the ratio of the sensitivity at two green pixels at different positions of the PDAF pixel is approximately 2.8. However, in a solid-state imaging device without the optical waveguide layer of this embodiment, the ratio of the sensitivity at two green pixels at different positions of the PDAF pixel is approximately 1.9. Therefore, it can be seen that using the optical waveguide layer of this embodiment can increase the phase difference of the PDAF pixel, thereby enhancing the PDAF function of the solid-state imaging device.

[0054] In solid-state imaging devices, incident light strikes the edges of a pixel array at an angle greater than the normal angle at which the incident light strikes the central region of the pixel array. This angled incident light striking the edges of the pixel array, or striking the surrounding area outside the central area of ​​the solid-state imaging device, causes reduced sensitivity at those pixels. According to embodiments of the invention, an offset is provided for the position of the waveguide partition grid for regular pixels, PDAF pixels, or combinations thereof, to enhance sensitivity at the edges of the pixel array or in the surrounding area of ​​the solid-state imaging device.

[0055] Figure 6A The diagram shows a cross-sectional view of a portion of a solid-state imaging device 200C according to some embodiments of the invention, which has regular pixels in the central region of the pixel array or in the core region of the solid-state imaging device 200C. Reference Figure 6A In the central region of the pixel array or in the core region of the solid-state imaging device 200C, the position of the waveguide separator grid 123A is aligned with the position of the color filter separator grid 113B without offset. For example... Figure 6AAs shown, the center lines 123CL of individual separators in waveguide separator grid 123A are aligned in a straight line with the center lines 113CL of individual separators in color filter separator grid 113B. Furthermore, in the central region of the pixel array or in the core region of the solid-state imaging device 200C, the left sidewalls 123LS-C of the separators in waveguide separator grid 123A are not offset relative to the left sidewalls of the separators in color filter separator grid 113B.

[0056] Figure 6B The diagram shows a cross-sectional view of a portion of a solid-state imaging device 200E according to some embodiments, which has regular pixels at the edges of the pixel array or in the surrounding area outside the core region of the solid-state imaging device 200E. Reference Figure 6B At the edge of the pixel array or in the area surrounding the solid-state imaging device 200E, the position of the waveguide partition grid 123A is offset by a displacement distance ΔX in direction D relative to the position of the color filter partition grid 113B. Direction D is a horizontal direction on a plane parallel to the top surface of the optical waveguide layer 130. For example, direction D can be the X-axis direction, the Y-axis direction, or a tilted direction relative to the X-axis and Y-axis directions. Figure 6B The centerline 123CL of individual separators in waveguide separator grid 123A is not aligned with the centerline 113CL of individual separators in color filter separator grid 113B. There is a displacement distance ΔX between the centerlines 123CL and 113CL. This displacement distance ΔX of waveguide separator grid 123A can be adjusted based on sensitivity, channel separation, or other performance characteristics at the edge of the pixel array or in the region surrounding the solid-state imaging device 200E. Furthermore, at the edge of the pixel array or in the region surrounding the solid-state imaging device 200E, the position of the left sidewall 123LS-E of the separators in waveguide separator grid 123A also has a displacement distance ΔX relative to the set position of the left sidewall 123LS-C of the separators in the center region of the pixel array or the core region of the solid-state imaging device 200C. In some embodiments, the displacement distance ΔX of waveguide separator grid 123A is consistent at each pixel.

[0057] According to embodiments of the present invention, such as Figure 6B As shown, at the edge of the pixel array or in the region surrounding the solid-state imaging device, the obliquely incident light 150E illuminating the regular pixels can be guided by the offset waveguide partition grid 123A and waveguide material 121 into the color filter segment 115, and reach a position close to the center region of the photoelectric conversion element 103. Therefore, the sensitivity at the edge of the pixel array or in the region surrounding the solid-state imaging device can be enhanced.

[0058] Figure 7AThe diagram shows a cross-sectional view of a portion of a solid-state imaging device 300C according to some embodiments of the invention, which has PDAF pixels in the central region of the pixel array or in the core region of the solid-state imaging device 300C. Reference Figure 7A The waveguide partition grid 123A is aligned with the position of the color filter partition grid 113B without offset. Furthermore, the center lines 123CL of the individual partitions of the waveguide partition grid 123A are aligned in a straight line with the center lines 113CL of the individual partitions of the color filter partition grid 113B. Figure 7A As shown. In addition, in the central region of the pixel array or in the core region of the solid-state imaging device 300C, the left sidewall 123LS-C of the waveguide separator 123A in the PDAF pixel is not offset relative to the left sidewall of the color filter separator 113B.

[0059] Figure 7B The diagram shows a cross-sectional view of a portion of a solid-state imaging device 300E according to some embodiments, which has PDAF pixels at the edges of the pixel array or in the surrounding area outside the core region of the solid-state imaging device 300E. Reference Figure 7B At the edge of the pixel array or in the area surrounding the solid-state imaging device 300E, the position of the waveguide separator grid 123A in the PDAF pixel is offset by a displacement distance ΔX in direction D relative to the position of the color filter separator grid 113B. Direction D is a horizontal direction on a plane parallel to the top surface of the optical waveguide layer 130. For example, direction D can be the X-axis direction, the Y-axis direction, or an inclined direction relative to the X-axis and Y-axis directions. Figure 7B As shown, the center line 123CL of an individual separator in waveguide separator grid 123A is not aligned with the center line 113CL of an individual separator in color filter separator grid 113B, and a displacement distance ΔX exists between the center lines 123CL and 113CL. The displacement distance ΔX can be adjusted based on sensitivity, channel separation, or other performance characteristics at the edge of the pixel array or in the area surrounding the solid-state imaging device 300E. Furthermore, at the edge of the pixel array or in the area surrounding the solid-state imaging device 300E, the left sidewall 123LS-E of the separator in waveguide separator grid 123A within the PDAF pixel also has a displacement distance ΔX relative to the set position of the left sidewall 123LS-C of the separator in waveguide separator grid 123A in the central region of the pixel array or the core region of the solid-state imaging device 300C.

[0060] According to embodiments of the present invention, such as Figure 7BAs shown, at the edge of the pixel array or in the region surrounding the solid-state imaging device, for a solid-state imaging device with a positionally offset waveguide partition grid 123A and waveguide material 121, the obliquely incident light 150E illuminating the PDAF pixel can be guided into the color filter segment 115 and reach the positions of multiple photoelectric conversion elements 103 in the PDAF pixel to increase the phase difference between two different positions in the PDAF pixel. Therefore, the PDAF function can be enhanced at the edge of the pixel array or in the region surrounding the solid-state imaging device.

[0061] although Figure 6A , Figure 6B , Figure 7A and Figure 7B The structure is shown separately to illustrate regular pixels and PDAF pixels, and to illustrate the central and edge regions of the pixel array, or the core and surrounding regions of the solid-state imaging device. It is understood that... Figure 6A , Figure 6B , Figure 7A and Figure 7B These structures shown can be combined together in a solid-state imaging device.

[0062] Figures 8 to 11 show cross-sectional views of some solid-state imaging devices with various top-guided structures according to some embodiments of the present invention. (Reference) Figure 8 In some embodiments, the solid-state imaging device 400 includes a planarization layer 125 between the optical waveguide layer 130 and the color filter layer 120. The planarization layer 125 is made of a transparent dielectric or insulating material with a refractive index lower than that of the waveguide material 121 of the optical waveguide layer 130, or equal to that of the waveguide partition grid 123A. The planarization layer 125 is formed on the color filter layer 120 using a coating or deposition process prior to the formation of the optical waveguide layer 130. The planarization layer 125 can serve as an etch stop layer in the etching process to protect the underlying color filter layer 120 when the waveguide material 121 is etched to form openings for filling the waveguide partition grid 123A. The planarization layer 125 can be made of the same material as the anti-reflective film 123B of the optical waveguide layer 130. In some examples, the thickness of the planarization layer 125 is from about 10 nm to about 100 nm. Furthermore, the various components of the optical waveguide layer 130, color filter layer 120, and photoelectric conversion structure 110 in the solid-state imaging device 400 can be related to the above-mentioned... Figure 3 The solid-state imaging device 200 describes the same or similar components.

[0063] refer to Figure 9In some embodiments, the solid-state imaging device 500 may further include a protective layer 127 on the optical waveguide layer 130, which prevents moisture from penetrating into the solid-state imaging device. The protective layer 127 may be made of an inorganic transparent insulating material with a refractive index lower than that of the waveguide material 121 of the optical waveguide layer 130. Furthermore, the refractive index of the protective layer 127 is lower than or equal to the refractive index of the waveguide partition grid 123A. The protective layer 127 may be formed on the anti-reflective film 123B of the optical waveguide layer 130 using deposition processes such as CVD, PVD, or ALD, or coating processes. The protective layer 127 is made of a material different from that of the anti-reflective film 123B. In some examples, the thickness of the protective layer 127 is from about 10 nm to about 100 nm. Furthermore, various elements of the optical waveguide layer 130, color filter layer 120, and photoelectric conversion structure 110 in the solid-state imaging device 500 may be related to the above-described... Figure 3 The solid-state imaging device 200 abbreviated describes those components as the same or similar.

[0064] refer to Figure 10 In some embodiments, the solid-state imaging device 600 may include an additional optical waveguide layer 140 on the optical waveguide layer 130. The optical waveguide layer 140 includes a waveguide material 131, a waveguide partition grid 133A, and an anti-reflective film 133B. The materials and processes used to form the optical waveguide layer 140 may be the same as or similar to those described above regarding the optical waveguide layer 130. Furthermore, when etching the material layer of the waveguide material 131 to form openings for filling the waveguide partition grid 133A, the anti-reflective film 123B of the optical waveguide layer 130 may serve as an etch stop layer in the etching process to protect the underlying structure.

[0065] In some embodiments, the refractive index of the waveguide material 121 of the lower optical waveguide layer 130 is higher than the refractive index of the waveguide material 131 of the upper optical waveguide layer 140. Furthermore, although Figure 10 The solid-state imaging device 600 shows only one additional optical waveguide layer 140, but one or more additional optical waveguide layers may be stacked on top of the underlying optical waveguide layer 130. Furthermore, the refractive index of the waveguide materials of these stacked optical waveguide layers may be uniform, or the refractive index of these waveguide materials may gradually increase in the direction toward the color filter layer 120. In a direction perpendicular to the top surface of the optical waveguide layer 130, the waveguide partition grid 133A of the optical waveguide layer 140 is aligned with the waveguide partition grid 123A of the optical waveguide layer 130. In some embodiments, the upper waveguide partition grid 133A, the lower waveguide partition grid 123A, and the color filter partition grid 113B may be made of the same material. Furthermore, the various elements of the optical waveguide layer 130, optical waveguide layer 140, color filter layer 120, and photoelectric conversion structure 110 in the solid-state imaging device 600 may be related to the above-described... Figure 3 The solid-state imaging device 200 describes the same or similar components.

[0066] refer to Figure 11 In some embodiments, the optical waveguide layer 130 of the solid-state imaging device 700 has waveguide materials 121 with different sizes at adjacent pixels. In some embodiments, such as Figure 11 As shown, multiple portions of the waveguide material 121 at the first pixel P1, the second pixel P2, and the third pixel P3 have different widths W1, W2, and W3, respectively. In some examples, the waveguide material 121 has different area dimensions at adjacent pixels. Furthermore, the size variation of the waveguide material 121 at different pixels can be periodic or aperiodic. Different sizes of the waveguide material 121 at different pixels can be obtained by adjusting the width of the separators of the waveguide separator grid 133A at different pixels. Additionally, the different sizes of the waveguide material 121 at different pixels can be combined with the displacement of the waveguide separator grid 123A for use in the same solid-state imaging device. Furthermore, the various elements of the color filter layer 120 and the photoelectric conversion structure 110 in the solid-state imaging device 700 can be used in conjunction with the above-described... Figure 3 The components described in the solid-state imaging device 200 are the same as or similar to those in the solid-state imaging device 200. Additionally, although Figures 8 to 11 The structures are shown separately to illustrate the different structural variations, which is understandable. Figures 8 to 11 These structures shown can also be used in combination within the same solid-state imaging device.

[0067] According to an embodiment of the present invention, an optical waveguide layer is provided disposed above the color filter layer of a solid-state imaging device. The optical waveguide layer comprises a waveguide partition grid and waveguide material in the gaps of the waveguide partition grid. The refractive index of the waveguide material is higher than the low refractive index of the waveguide partition grid, causing total internal reflection at the walls of the waveguide partition grid, and the waveguide material can restrict the propagation of incident light toward the color filter segment. Therefore, the optical waveguide layer of the present invention can avoid crosstalk interference at the corners of the solid-state imaging device and enhance the phase detection autofocus (PDAF) function.

[0068] The foregoing has outlined components of several embodiments to enable those skilled in the art to better understand the concepts of the embodiments of the present invention. Those skilled in the art should understand that the embodiments of the present invention can be used as a basis to design or modify other processes and structures to achieve the same objectives and / or advantages as the embodiments described herein. Those skilled in the art should also understand that these equivalent structures do not depart from the concept and scope of the present invention, and various changes, substitutions, and other options can be made therein without departing from the concept and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A solid-state imaging device, comprising: Multiple photoelectric conversion elements are arranged in a pixel array; A color filter layer includes multiple color filter segments and a color filter dividing grid. The multiple color filter segments are located above the multiple photoelectric conversion elements. The multiple color filter segments are disposed in the gaps of the color filter dividing grid, and each color filter segment is disposed in an individual pixel of the pixel array. An optical waveguide layer, located above the color filter layer, comprises a waveguide partition grid and waveguide material located in the gaps of the waveguide partition grid. The refractive index of the waveguide material is higher than that of the waveguide partition grid, and the waveguide material provides the same refractive index in each pixel of the pixel array. The color filter separator grid is located below the waveguide separator grid, and the plurality of color filter segments and the color filter separator grid have a coplanar top surface; The waveguide separator grid and the color filter separator grid are in direct contact with each other, and the pixel array includes a plurality of first pixels located in the central region of the pixel array or the core region of the solid-state imaging device, and a plurality of second pixels located at the edge of the pixel array or in the surrounding region outside the core region of the solid-state imaging device. In the plurality of first pixels, the center lines of individual separators of the waveguide separator grid are aligned with the center lines of individual separators of the color filter separator grid in a direction perpendicular to the top surface of the optical waveguide layer; In the plurality of second pixels, the center lines of individual separators of the waveguide separator grid are not aligned with the center lines of individual separators of the color filter separator grid, and have a displacement distance in a horizontal direction parallel to the top surface of the optical waveguide layer.

2. The solid-state imaging device of claim 1, wherein the refractive index of the color filter dividing grid is lower than the refractive index of the plurality of color filter segments.

3. The solid-state imaging device of claim 2, wherein the plurality of first pixels includes a plurality of phase detection autofocus (PDAF) pixels, the plurality of PDAF pixels comprising a plurality of the plurality of photoelectric conversion elements disposed below the plurality of color filter segments, and the plurality of color filter segments in the plurality of PDAF pixels having the same color and being in contact with each other.

4. The solid-state imaging apparatus of claim 2, wherein the plurality of displacement distances of the waveguide partition grid in the plurality of second pixels are consistent.

5. The solid-state imaging apparatus of claim 2, wherein the plurality of displacement distances of the waveguide separating grids in the plurality of second pixels are different from each other.

6. The solid-state imaging device of claim 2, wherein the plurality of second pixels includes a plurality of phase detection autofocus pixels, the plurality of phase detection autofocus pixels includes a plurality of the plurality of photoelectric conversion elements disposed below the plurality of color filter segments, and the plurality of color filter segments in the plurality of phase detection autofocus pixels have the same color and are in contact with each other.

7. The solid-state imaging apparatus according to any one of claims 1 to 6, further comprising: An anti-reflective film is located on the top surface of the waveguide material and the waveguide partition mesh, which are coplanar and are made of the same material and formed together in the same process steps.

8. The solid-state imaging apparatus of any one of claims 1 to 7, wherein the waveguide material in different pixels has different widths, the plurality of widths vary periodically or non-periodically, and the plurality of different widths are combined with the displacement of the waveguide partition grid in the plurality of second pixels relative to the color filter partition grid in the same solid-state imaging apparatus.

9. The solid-state imaging apparatus of claim 3 or 6, wherein in each of the phase-detection autofocus pixels, multiple portions of the waveguide material located above the plurality of color filter segments having the same color and in contact with each other are connected to each other and surrounded by the waveguide separation grid to separate them from the waveguide material in adjacent regular pixels.

10. The solid-state imaging apparatus of claim 7, wherein the waveguide material and the waveguide partition grid have a coplanar top surface, the waveguide partition grid is composed of a transparent dielectric material filled in a plurality of openings formed in the waveguide material, the anti-reflective film continuously covers the coplanar top surface, and the anti-reflective film and the waveguide partition grid constitute an integral structure formed of the same transparent dielectric material.

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