Image sensor

Abstract

To provide an image sensor with improved electrical and optical characteristics. [Solution] The image sensor of the present invention comprises a substrate including a first surface and a second surface facing the first surface; a separation pattern disposed within the substrate and defining a first sensing region and a second sensing region; a short element isolation film disposed adjacent to the first surface; local nodes disposed on the short element isolation film; and node doping regions disposed in contact with the local nodes, wherein the local nodes do not overlap perpendicularly with the separation pattern, and the local nodes contain polysilicon.

Description

Technical Field

[0001] The present invention relates to an image sensor, and more particularly, to an image sensor with improved electrical and optical characteristics.

Background Art

[0002] An image sensor converts an optical image into an electrical signal. Recently, with the development of the computer and communication industries, the demand for image sensors with improved performance in various fields such as digital cameras, video cameras, PCS (Personal Communication System), game devices, security cameras, and medical micro cameras has been increasing. [[ID=十三]]

[0003] Image sensors include charge-coupled devices (CCDs) and CMOS image sensors. Among these, CMOS image sensors have a simple driving method and can integrate signal processing circuits on a single chip, enabling miniaturization of products. CMOS image sensors also have very low power consumption, making them easy to apply to products with limited battery capacity. In addition, CMOS image sensors can use CMOS process technologies interchangeably, reducing manufacturing costs. Therefore, as high resolution becomes achievable with technological development, the use of CMOS image sensors has been increasing rapidly.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above-mentioned prior art, and the object of the present invention is to provide an image sensor having improved electrical and optical characteristics. [Means for solving the problem]

[0006] An image sensor according to one aspect of the present invention, made to achieve the above objective, comprises a substrate including a first surface and a second surface facing the first surface; a separation pattern disposed within the substrate and defining a first sensing region and a second sensing region; a short element isolation film disposed adjacent to the first surface; local nodes disposed on the short element isolation film; and node doping regions disposed in contact with the short element isolation film, wherein the local nodes do not overlap the separation pattern perpendicularly, and the local nodes contain polysilicon.

[0007] An image sensor according to another aspect of the present invention made to achieve the above objectives comprises a substrate including a first surface and a second surface facing the first surface; a separation pattern disposed within the substrate and defining a first sensing region and a second sensing region; a short element isolation film disposed adjacent to the first surface; a local node disposed on the short element isolation film; and a node doping region disposed in contact with the short element isolation film, wherein the local node is disposed between adjacent and spaced-apart separation patterns, the local node contains polysilicon, the upper surface of the short element isolation film is in contact with the lower surface of the local node, and the node doping region and the local node are electrically connected.

[0008] An image sensor according to yet another aspect of the present invention made to achieve the above objectives comprises a substrate having a first surface and a second surface opposite to the first surface; a separation pattern defining a sensing region within the substrate; a photoelectric conversion region provided within the substrate; a short element isolation film adjacent to the first surface of the substrate; a transmission gate electrode disposed adjacent to the first surface of the substrate; a local node disposed on the short element isolation film; a node doping region disposed in contact with the short element isolation film; a color filter disposed on the second surface of the substrate corresponding to the sensing region; and a microlens on the color filter, wherein the local node is disposed between adjacent and spaced-apart separation patterns, the local node contains polysilicon, the upper surface of the short element isolation film is in contact with the lower surface of the local node, and the level of the lower surface of the node doping region is between the level of the lower surface of the local node and the level of the lower surface of the short element isolation film.

[0009] Specific details of other embodiments are included in the detailed description and drawings. [Effects of the Invention]

[0010] According to the present invention, there is a region where only a short element isolation film is formed at the boundary with adjacent pixels without a separation pattern. By adding polysilicon to this region to form a common floating or ground node between adjacent pixels, the conversion gain at the unit pixel can be improved. Furthermore, the degree of freedom in wiring the image sensor can be improved.

[0011] Furthermore, by forming polysilicon wiring in contact with the floating node, electrical connection with adjacent gates can be achieved. [Brief explanation of the drawing]

[0012] [Figure 1] This is a plan view of the first example image sensor according to one embodiment of the present invention. [Figure 2A]This is a cross-sectional view of a first example of an image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 1. [Figure 2B] This is a cross-sectional view of a second example of an image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 1. [Figure 2C] This is a cross-sectional view of a third example of an image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 1. [Figure 2D] This is a cross-sectional view of a fourth example of the first example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 1. [Figure 3] This is a plan view of a second example image sensor according to one embodiment of the present invention. [Figure 4] This is a cross-sectional view of a second example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 3. [Figure 5] This is a plan view of a third example image sensor according to one embodiment of the present invention. [Figure 6A] This is a cross-sectional view of a third example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line X-X' in Figure 5. [Figure 6B] This is a cross-sectional view of a third example image sensor according to one embodiment of the present invention, showing a cross-section cut along the Y-Y' line in Figure 5. [Figure 7] This is a plan view of the fourth example image sensor according to one embodiment of the present invention. [Figure 8] This is a plan view of the fifth example image sensor according to one embodiment of the present invention. [Figure 9] This is a cross-sectional view of each step in a second example of a method for manufacturing an image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 3. [Figure 10] This is a cross-sectional view of each step in a second example of a method for manufacturing an image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 3. [Figure 11]A cross-sectional view of each step of a method for manufacturing a second example image sensor according to an embodiment of the present invention, showing a cross-section cut along line A-A' of FIG. 3. [Figure 12] A cross-sectional view of each step of a method for manufacturing a second example image sensor according to an embodiment of the present invention, showing a cross-section cut along line A-A' of FIG. 3.

Mode for Carrying Out the Invention

[0013] Hereinafter, specific examples of the mode for carrying out the image sensor of the present invention will be described in detail with reference to the drawings.

[0014] FIG. 1 is a plan view of a first example image sensor according to an embodiment of the present invention. FIG. 2A is a cross-sectional view of a first example of a first example image sensor according to an embodiment of the present invention, showing a cross-section cut along line A-A' of FIG. 1.

[0015] Referring to FIGS. 1 and 2A, the image sensor according to the present embodiment includes a plurality of sensing regions P arranged two-dimensionally, and each sensing region P converts an optical signal into an electrical signal.

[0016] The image sensor according to the present embodiment has a substrate 100 including a first surface 100a and a second surface 100b facing the first surface 100a.

[0017] The substrate 100 is, for example, a single crystal silicon wafer, a silicon epitaxial layer, or an SOI (silicon on insulator) substrate. For example, the substrate 100 is doped with an impurity having a first conductivity type (for example, P-type). The substrate 100 includes a first surface 100a and a second surface 100b facing each other. The substrate 100 has a plate shape extending in a first direction D1 and a second direction D2 intersecting the first direction.

[0018] The first surface 100a is separated from the second surface 100b in a third direction D3. The second surface 100b is separated from the first surface 100a in a third direction D3. The third direction D3 is a direction perpendicular to the first surface 100a and the second surface 100b of the substrate 100 with respect to the upper surface of the substrate 100.

[0019] The image sensor according to the present invention includes a plurality of sensing regions P. As an example, it includes first, second, third, and fourth sensing regions (P1, P2, P3, P4) arranged in order along a clockwise direction. The first and second sensing regions (P1, P2) are arranged side by side along a third direction D3, and the third and fourth sensing regions (P3, P4) are also arranged side by side along a first direction D1. The second and third sensing regions (P2, P3) are arranged side by side along a second direction D2, and the first and fourth sensing regions (P1, P4) are also arranged side by side along a second direction D2. The first pixel (P1) and the third pixel (P3) are spaced apart in the fourth direction D4. The second pixel (P2) and the fourth pixel (P4) are spaced apart in the fifth direction D5 which intersects the fourth direction D4.

[0020] Local node SN is placed between the first pixel (P1) and the third pixel (P3), and between the second pixel (P2) and the fourth pixel (P4). Separation pattern 11 is not provided in the area where local node SN is placed.

[0021] The separation pattern 11 defines multiple sensing regions P. The separation pattern 11 is located within a separation trench DTR extending from the first surface 100a toward the second surface 100b. In plan view, the separation pattern 11 has a mesh shape where lines extending in the first and second directions (D1, D2) intersect, except in the region where the local node SN is located. The separation pattern 11 penetrates the substrate 100. Multiple photoelectric conversion regions PD are arranged between the separation pattern 11, spaced apart from each other.

[0022] A separation pattern 11 is arranged on the substrate 100 to separate multiple sensing regions. An element isolation film 12 is arranged on the substrate 100 to define the active region. The element isolation film 12 includes a shallow element isolation film 122 and a short element isolation film 121. The element isolation film 12 is arranged adjacent to the first surface 100a of the substrate. The element isolation film 12 has a shape that is inserted into the interior from the first surface 100a of the substrate. As an example, the element isolation film 12 includes a silicon oxide film and a silicon nitride film.

[0023] The element isolation film 12 has a mesh shape in a plan view, where lines extending in the first and second directions (D1, D2) intersect. Multiple short element isolation films 121 separate the photoelectric conversion section PD. The photoelectric conversion section PD is doped with an impurity of a second conductivity type, which is opposite to the first conductivity type. The second conductivity type is, for example, N-type. The N-type impurity region formed by doping the photoelectric conversion section PD forms a PN junction with the adjacent P-type impurity region of the substrate 100 to provide a photodiode.

[0024] On the first surface 100a of the substrate 100, a separation pattern 11 that separates the sensing region, a shallow element separation film 122 connected to the separation pattern 11, and a short element separation film 121 provided between adjacent and separated separation patterns 11 and positioned between the photoelectric conversion region PD are arranged. The shallow element separation film 122 and the short element separation film 121 define the active region of the substrate 100.

[0025] The isolation pattern 11 includes a conductive pattern 113 positioned within the isolation trench DTR, and an isolation insulating film 111 surrounding the sides of the conductive pattern 113. The conductive pattern 113 includes a conductive material, such as metal or polysilicon doped with impurities. The isolation insulating film 111 includes a silicon oxide film. A shallow element isolation film 122 is provided between the isolation pattern 11 and the first surface 100a.

[0026] A transmission gate TG is provided on the first surface 100a of the substrate 100 in each sensing region P. As an example, a portion of the transmission gate TG is embedded inside the substrate 100. The transmission gate TG is of the vertical type. As an example, the first portion of the transmission gate TG is extended from the first surface 100a of the substrate 100 to the substrate 100 and provided inside the substrate 100, and the second portion is provided on the first surface 100a of the substrate 100. That is, a portion of the transmission gate TG is extended inside the substrate 100. The transmission gate TG is the gate electrode (transmission gate electrode) of a transmission transistor.

[0027] As another example, the transmission gate TG may be of a planar type, having a flat shape on the first surface 100a of the substrate 100.

[0028] A gate insulating film GI is interposed between the transmission gate TG and the substrate 100. A floating region is provided within the substrate 100 adjacent to one side of the transmission gate TG. The floating region is doped with a conductivity type opposite to that of the substrate. As an example, an impurity having a second conductivity type is doped into the floating region.

[0029] According to this embodiment, light is incident on the substrate 100 through the second surface 100b of the substrate 100. Electron-hole pairs are generated at the PN junction by the incident light. The electrons thus generated move to the photoelectric conversion region PD. The electrons move to the floating region when a voltage is applied to the transmission gate TG.

[0030] An interlayer insulating film (ILD) is provided on the first surface 100a of the substrate 100. The interlayer insulating film (ILD) covers the first surface 100a. The interlayer insulating film (ILD) is a composite film comprising at least one film from among a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a porous low dielectric film, or a combination thereof. A wiring CLN is provided within the interlayer insulating film (ILD). A floating region is connected to the wiring CLN. The floating region is included in a node doping region 1011, which will be described later.

[0031] A flat insulating film 42 covers the second surface 100b of the substrate 100. The flat insulating film 42 is formed of a transparent insulating material and includes multiple layers. The flat insulating film 42 is formed of an insulating material having a different refractive index than the substrate 100. The flat insulating film 42 includes a metal oxide and / or silicon oxide.

[0032] The lattice structure 320 is placed on the flat insulating film 42. The lattice structure 320 has a lattice shape in plan view, similar to the separation pattern 11. The lattice structure 320 superimposes the separation pattern 11 in plan view. That is, the lattice structure 320 includes a first portion extending in a first direction D1, and a second portion extending in a second direction D2 across the first portion. The width of the lattice structure 320 is substantially the same as or less than the minimum width of the separation pattern 11.

[0033] The lattice structure 320 includes a light-shielding pattern and / or a low-refractive-index pattern. The light-shielding pattern includes a metallic material such as titanium, tantalum, or tungsten. The low-refractive-index pattern is formed of a material having a lower refractive index than the conductive pattern. The low-refractive-index pattern is formed of an organic material and has a refractive index of about 1.1 to 1.3. For example, the lattice structure is a polymer layer containing silica nanoparticles.

[0034] The color filter CF is placed between the grid structure 320 and on top of the flat insulating film 42. The color filter CF fills the space defined by the grid structure 320. The color filter CF includes red, green, or blue color filters depending on the unit pixel, or magenta, cyan, or yellow color filters. As another example, part of the color filter CF may include an infrared filter.

[0035] A microlens ML is placed on a color filter CF. The microlens ML has a bulging shape and a predetermined radius of curvature. The microlens ML is made of a light-transmitting resin. The microlens ML is placed on the corresponding color filter CF.

[0036] A local node SN is provided on a short element isolation film 121. A node doping region 1011 is provided so as to be in contact with the short element isolation film 121 and the local node SN. The short element isolation film 121, the local node SN, the node doping region 1011, and a plurality of transmission gates TG are arranged between adjacent, spaced-apart isolation patterns 11. A transmission gate electrode TG is arranged between the short element isolation film 121 and the isolation patterns 11. The local node SN does not overlap the isolation patterns 11. In the plan view, the local node SN is arranged between isolation patterns 11 spaced apart in a first direction D1.

[0037] The local node SN contains polysilicon. The local node SN contains doped polysilicon. The node doping region 1011 contains polysilicon. The node doping region 1011 contains doped polysilicon. The local node SN and the node doping region 1011 are doped with the same type of dopant. Doping with the same type of dopant means doping with a dopant of the same polarity. As an example, an impurity having a second conductivity type is doped into the local node SN and / or the node doping region 1011.

[0038] The lower surface SN_2s of the local node SN is in contact with the short element isolation film 121. The upper surface SN_1s of the local node SN is in contact with the interlayer insulating film ILD. The upper surface SN_1s of the local node SN is coplane with the first surface 100a of the substrate 100. The upper surface SN_1s of the local node SN is coplane with the upper surface of the node doping region 1011. The upper surface SN_1s of the local node SN is coplane with the upper surface of the shallow element isolation film 122. The upper surface of the shallow element isolation film 122 is in contact with the interlayer insulating film ILD.

[0039] The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface 1011bs of the node doping region 1011. The level of the lower surface 1011bs of the node doping region 1011 is higher than the level of the lower surface 121bs of the short element isolation film 121. The level of the lower surface 1011bs of the node doping region 1011 is higher than the level of the lower surface 122bs of the shallow element isolation film 122. The level of the lower surface 121bs of the short element isolation film 121 is substantially the same as the level of the lower surface 122bs of the shallow element isolation film 122. The level of the lower surface 1011bs of the node doping region 1011 is between the level of the lower surface SN_2s of the local node SN and the level of the lower surface 121_bs of the short element isolation film 121.

[0040] In this specification, substantially identical means identical within a margin of error of 5%.

[0041] In this specification, a higher level for one configuration than for another means that the distance from the second surface 100b of the substrate 100 of one configuration is longer than the distance from the second surface 100b of the substrate 100 of the other configuration. In other words, in this specification, a higher level for one configuration than for another means that the distance from the first surface 100a of the substrate 100 of one configuration is shorter than the distance from the first surface 100a of the substrate 100 of the other configuration.

[0042] In this embodiment, the image sensor is provided with a short element isolation film 121 in the region where the isolation pattern 11 was not provided, and local nodes SN are provided on the short element isolation film 121. Since the local nodes SN and the node doping region 1011 are connected, it is advantageous for pixel miniaturization.

[0043] A microlens ML is placed on the second surface 100b of the substrate 100. Adjacent and spaced-apart photoelectric conversion regions PD, between which no separation pattern 11 is provided, are superimposed perpendicularly on one microlens ML. Adjacent and spaced-apart photoelectric conversion regions PD and short element isolation films 121 placed between them are superimposed perpendicularly on one microlens ML. In other words, multiple spaced-apart photoelectric conversion regions PD are placed between adjacent and spaced-apart separation patterns 11.

[0044] Figure 2B is a cross-sectional view of a second example of the first example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 2. For the sake of simplicity, explanations that are redundant with those previously explained are omitted.

[0045] Referring to Figure 2B, the local node SN is provided on the short element isolation film 121. The upper surface of the short element isolation film 121 is coplane with the first surface 100a of the substrate 100. The upper surface of the short element isolation film 121 is coplane with the upper surface of the node doping region 1011.

[0046] The local node SN protrudes from the first surface 100a of the substrate 100 toward the interlayer insulating film ILD. The local node SN protrudes from the first surface 100a of the substrate 100 toward the short element isolation film 121. The lower surface SN_2s of the local node SN is coplane with the first surface 100a of the substrate 100. The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface 121bs of the short element isolation film 121. The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface 122bs of the shallow element isolation film 122.

[0047] The upper surface SN_1s of the local node SN is in contact with the interlayer insulating film ILD. The level of the upper surface SN_1s of the local node SN is lower than the level of the upper surface TGt of the transmission gate TG, and higher than the level of the upper surface of the node doping region 1011.

[0048] The local node SN covers a portion of the upper surface of the node doping region 1011. Therefore, the local node SN is electrically connected to the node doping region 1011. The local node SN is in contact with the upper surface of the short element isolation film 121 and the upper surface of the node doping region 1011. The sidewall of the node doping region 1011 is in contact with the sidewall of the short element isolation film 121.

[0049] Figure 2C is a cross-sectional view of a third example of the first example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 2. For the sake of simplicity, explanations that are redundant with those previously explained are omitted.

[0050] According to Figure 2C, the local node SN is provided on the short element isolation film 121. The level of the upper surface of the short element isolation film 121 is lower than the level of the first surface 100a of the substrate 100. The level of the upper surface of the short element isolation film 121 is lower than the level of the upper surface of the node doping region 1011. The upper surface of the node doping region 1011 is coplane with the first surface 100a of the substrate 100.

[0051] The local node SN passes through the first surface 100a of the substrate 100 and protrudes from the interlayer insulating film ILD toward the short element isolation film 121. The local node SN has a shape that extends into a part of the interlayer insulating film ILD and a part of the substrate 100.

[0052] The level of the upper surface SN_1s of local node SN is higher than the level of the first surface 100a of substrate 100. The level of the upper surface SN_1s of local node SN is higher than the level of the upper surface of node doping region 1011.

[0053] The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface 121bs of the short element isolation film 121. The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface 122bs of the shallow element isolation film 122. The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface of the node doping region 1011. The level of the lower surface SN_2s of the local node SN is lower than the level of the upper surface of the node doping region 1011.

[0054] The upper surface SN_1s of the local node SN is in contact with the interlayer insulating film ILD. The level of the upper surface SN_1s of the local node SN is lower than the level of the upper surface TGt of the transmission gate TG, and higher than the level of the upper surface of the node doping region 1011.

[0055] The sidewall of the local node SN is in contact with the node doping region 1011. The sidewall of the node doping region 1011 is in contact with the sidewall of the local node SN and the short element isolation film 121.

[0056] Figure 2D is a cross-sectional view of a fourth example of the first example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 1. For the sake of simplicity, explanations that are redundant with those previously explained are omitted.

[0057] According to Figure 2D, local nodes SN are provided on a short element isolation film 121 and a node doping region 1011. The level of the upper surface of the short element isolation film 121 is lower than the level of the first surface 100a of the substrate 100. The level of the upper surface of the short element isolation film 121 is lower than the level of the upper surface of the node doping region 1011. The upper surface of the node doping region 1011 is coplane with the first surface 100a of the substrate 100.

[0058] The local node SN passes through the first surface 100a of the substrate 100 and protrudes from the interlayer insulating film ILD toward the short element isolation film 121. The local node SN has a shape that extends into a part of the interlayer insulating film ILD and a part of the substrate 100.

[0059] The level of the upper surface SN_1s of local node SN is higher than the level of the first surface 100a of substrate 100. The level of the upper surface SN_1s of local node SN is higher than the level of the upper surface of node doping region 1011.

[0060] The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface 121bs of the short element isolation film 121. The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface 122bs of the shallow element isolation film 122. The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface of the node doping region 1011. The level of the lower surface SN_2s of the local node SN is lower than the level of the upper surface of the node doping region 1011.

[0061] The length of the upper surface SN_1s of local node SN is longer than the length of the lower surface SN_2s of local node SN.

[0062] The local node SN includes an intermediate lower surface SN_3s. The intermediate lower surface SN_3s of the local node SN is in contact with the node doping region 1011. The intermediate lower surface SN_3s of the local node SN is electrically connected to the node doping region 1011.

[0063] The level of the intermediate lower surface SN_3s of local node SN is higher than the level of the lower surface SN_2s of local node SN. The level of the intermediate lower surface SN_3s of local node SN is between the level of the upper surface SN_1s of local node SN and the level of the lower surface SN_2s of local node SN. In other words, local node SN has a stepped portion near the node doping region 1011.

[0064] The upper surface SN_1s of the local node SN is in contact with the interlayer insulating film ILD. The sidewall of the local node SN is in contact with the interlayer insulating film ILD. The sidewall of the node doping region 1011 is in contact with the sidewall of the local node SN and the short element isolation film 121.

[0065] Figure 3 is a plan view of a second example image sensor according to one embodiment of the present invention. Figure 4 is a cross-sectional view of a second example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line A-A' in Figure 3. For the sake of simplicity, explanations that are redundant with those previously explained are omitted.

[0066] Referring to Figures 3 and 4, a ground node GN is provided on the separation pattern 11.

[0067] Multiple grounding nodes GN are arranged spaced apart in the second direction D2 and the first direction D1. Multiple photoelectric conversion regions are provided between adjacent, spaced-apart grounding nodes GN. Local nodes SN are provided between adjacent, spaced-apart grounding nodes GN. In Figure 4, the upper surface SN_1s of the local node SN is shown to be coplane with the first surface 100a of the substrate 100, similar to the local node SN in Figure 2A, but the form of the local node SN is not limited to this, and local node SN in any form from Figures 2A to 2C is also possible. The level of the upper surface SN_1s of the local node SN is not limited.

[0068] The ground node GN is positioned between the first surface 100a of the substrate 100 and the shallow element isolation film 122. The ground node GN is positioned on the shallow element isolation film 122. An intervening doping region 1012 is provided that is in contact with the ground node GN. The intervening doping region 1012 is in contact with the ground node GN and the shallow element isolation film 122.

[0069] The ground node GN contains polysilicon. The ground node GN contains polysilicon doped with a different dopant than the local node. The ground node GN contains polysilicon doped with the same type of dopant as the intervening doping region 1012. Doping with the same type of dopant means doping with a dopant of the same polarity.

[0070] The level of the upper surface GN_1s of the grounding node GN is coplane with the first surface 100a of the substrate 100. The level of the upper surface GN_1s of the grounding node GN is coplane with the intervening doping region 1012. The level of the lower surface GN_2s of the grounding node GN is substantially the same as the level of the lower surface SN_2s of the local node SN. The level of the lower surface SN_2s of the local node SN is higher than the level of the lower surface of the intervening doping region 1012.

[0071] Figure 5 is a plan view of a third example image sensor according to one embodiment of the present invention. Figure 6A is a cross-sectional view of a third example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line X-X' in Figure 5. Figure 6B is a cross-sectional view of a third example image sensor according to one embodiment of the present invention, showing a cross-section taken along the line Y-Y' in Figure 5. For the sake of simplicity, explanations that are redundant with those previously explained are omitted.

[0072] According to Figures 5, 6A, and 6B, a local wiring structure SST is provided, which includes a local node SN and a local wiring SW. Multiple sensing regions are connected by the local wiring structure SST.

[0073] Local wiring SW is positioned between the separated local nodes SN. Local wiring SW and local nodes SN contain polysilicon doped with the same type of dopant. Doping with the same type of dopant means doping with a dopant of the same polarity. Local wiring SW and local nodes SN form a single unit without a boundary. Local wiring is superimposed perpendicularly on the separation pattern 11.

[0074] Local nodes SN do not overlap perpendicularly with the isolation pattern 11. The isolation pattern 11 is interposed between the separated local nodes SN. A conductive pattern 113 and an isolation insulating film 111 on the side surface of the conductive pattern 113 are arranged between the separated local nodes SN. Local nodes SN are provided on areas of the substrate 100 where the isolation pattern 11 is not provided.

[0075] A shallow element isolation film 122 is provided on the conductive pattern 113 and the isolation insulating film 111. A short element isolation film 121 is provided on a region of the substrate 100 where the isolation pattern 11 is not provided, and a local node SN is provided on the short element isolation film 121 in this region.

[0076] A separation pattern 11 is interposed between multiple separated photoelectric conversion regions PD. A conductive pattern 113 and a separation insulating film 111 surrounding the conductive pattern 113 are arranged between the multiple separated photoelectric conversion regions PD. A shallow element isolation film 122 is provided on the separation pattern 11. A local wiring SW is arranged within the short element isolation film 121. The local wiring SW has the shape of a short element isolation film 121 from the first surface 100a of the substrate 100.

[0077] The width SW_w of the local wiring switch is smaller than the width of the short element isolation film 121. The width SW_w of the local wiring switch is smaller than the width SN_w of the local node signal line.

[0078] Local nodes SN are connected by a local wiring switch. Therefore, local nodes SN are electrically connected by the local wiring switch without the need for additional wiring.

[0079] Figure 7 is a plan view of a fourth example image sensor according to one embodiment of the present invention. For the sake of simplicity, we will mainly explain the differences from what was explained in Figure 6.

[0080] Referring to Figure 7, a local wiring structure SST is provided, which includes a local node SN and a local wiring SW. Multiple sensing regions are connected by the local wiring structure SST.

[0081] A source follower gate SF is provided. A local wiring SW is placed between isolated local nodes SN. The local wiring SW is provided to be connected to the source follower gate SF. The local wiring SW is arranged along the sensing area. The local wiring SW is superimposed on the isolation pattern 11.

[0082] Local wiring SW is provided so as to extend from local node SN along the pixel region and connect to source follower gate SF. Local wiring SW is provided along isolation pattern 11.

[0083] Figure 8 is a plan view of a fifth example image sensor according to one embodiment of the present invention. For the sake of simplicity, we will mainly explain the differences from those described above.

[0084] Referring to Figure 8, a ground node GN is provided. The ground node GN is provided so that it is surrounded by four sensing regions. The ground node GN includes, for example, polysilicon and is provided so that only the ground node GN does not superimpose on the separation pattern 11 without another local node SN. The ground node GN is located, for example, at the position of local node SN in Figure 1.

[0085] Figures 9, 10, 11, and 12 are cross-sectional views of each step in a second example of an image sensor manufacturing method according to one embodiment of the present invention, showing cross-sections cut along the line A-A' in Figure 3.

[0086] Referring to Figure 9, a photoelectric conversion region PD is formed on the substrate 100. The photoelectric conversion region PD is formed by doping the substrate 100 with a dopant. As an example, the photoelectric conversion region PD is formed by ion implanting a second conductivity type impurity using an ion implantation mask.

[0087] The element isolation film 12 and the isolation pattern 11 are formed. The element isolation film 12 is formed by creating trenches in the substrate and then filling the trenches with an insulating material.

[0088] The separation pattern 11 is formed by first creating trenches within the region of the substrate on which the shallow element separation film 122 is formed, then conformally covering the trenches with an insulating material, and finally filling them with a conductive material.

[0089] A region is formed between adjacent photoelectric conversion regions PD where the separation pattern 11 is not formed. The element isolation film formed on the region where the separation pattern 11 is not formed becomes a short element isolation film 121. A node doping region 1011 is formed around the short element isolation film 121. The node doping region 1011 is formed, for example, by ion implantation of a second conductivity type impurity.

[0090] Referring to Figure 10, a portion of the short element isolation film 121 is removed. Removing a portion of the short element isolation film 121 involves selectively removing only the short element isolation film 121 through a mask pattern (not shown). The removal of a portion of the short element isolation film 121 forms a first trench TR1. The first trench TR1 exposes the top surface of the short element isolation film 121 and the side surface of the node doping region 1011.

[0091] Referring to Figure 11, the first trench TR1 is filled with local node SN to form local node SN. Forming local node SN involves filling the first trench TR1 with polysilicon to cover the upper surface of the exposed short element isolation film 121 and the sides of the node doping region 1011. The polysilicon filling the first trench TR1 includes doped polysilicon.

[0092] Referring to Figure 12, a planarization process is performed so that the local node SN and the exposed upper surface of the substrate 100 become flat. Subsequently, the transmission gate TG is formed. Forming the transmission gate TG includes forming a trench in which the transmission gate TG is formed within the substrate 100, covering the trench with a gate insulating film GI, forming a transmission gate TG layer on the gate insulating film GI so as to fill the entire trench, and removing a portion of the transmission gate TG layer to form the transmission gate TG.

[0093] An interlayer insulating film (ILD) and a wiring CLN are provided. The interlayer insulating film (ILD) is formed on the first surface 100a of the substrate 100. A wiring CLN is formed within the interlayer insulating film (ILD).

[0094] Referring again to Figures 1 and 2A, a flat insulating film 42, a grid structure 320, a color filter CF between the grid structures 320, and a microlens ML on the color filter CF are formed on the second surface 100b. The image sensor shown in Figures 1 and 2A is then manufactured.

[0095] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is not limited to the embodiments described above, and can be modified and implemented in various ways without departing from the technical spirit of the present invention. [Explanation of Symbols]

[0096] 11 Separation Patterns 12-element separation membrane 42 Flat insulating film 100 circuit boards 100a, 100b: Pages 1 and 2 111 Separation Insulating Film 113 Conductive Patterns 121 Short element isolation film 121 bs Lower surface of short element isolation film 122 Shallow element separation membrane 122bs Shallow element isolation film bottom surface 320 Lattice Structure 1011 Node doping area Lower surface of the 1011bs node doping area 1012 Interventional Doping Domain CF Color Filter CLN wiring DTR Separation Trench GI gate insulating film GN Grounded Node GN_1s, GN_2s upper and lower surfaces of grounded nodes ILD (Interlayer Diode) ML Microlens P Sensing Area P1, P2, P3, P4: First to fourth sensing areas (first to fourth pixels) PD (Photoelectric Transformation) Region SF Source Follower Gate SN local node SN_1s, SN_2s, SN_3s: Top, bottom, and middle bottom surfaces of the local node. SST Local Wiring Structure SW local wiring TG Transmission Gate (Transmission Token) Top view of the TGt transmission gate TR1 Trench 1

Claims

1. A substrate including a first surface and a second surface facing the first surface, A separation pattern is disposed within the substrate and defines a first sensing region and a second sensing region. A short element isolation film is arranged adjacent to the first surface, A local node arranged on the short element isolation film, The short element isolation film comprises a node doping region positioned in contact with the aforementioned short element isolation film, The aforementioned local node does not superimpose perpendicularly on the separation pattern. The local node is an image sensor characterized by containing polysilicon.

2. The image sensor according to claim 1, characterized in that the local node is arranged to extend from the first surface toward the short element isolation film.

3. The upper surface of the short element isolation film and the first surface are in contact, The image sensor according to claim 1, characterized in that the local node protrudes from the first surface in the direction opposite to the short element isolation film.

4. The image sensor according to claim 1, characterized in that the level of the first surface is between the level of the upper surface of the local node and the level of the lower surface of the local node.

5. The aforementioned local node contains polysilicon doped with a dopant, The image sensor according to claim 1, characterized in that the node doping region includes polysilicon doped with the same polarity as the local node.

6. The separation pattern further includes a grounding node, The grounding node includes polysilicon, The image sensor according to claim 1, characterized in that the ground node and the local node are doped with different dopants.

7. The image sensor according to claim 6, characterized in that the level of the lower surface of the ground node and the level of the lower surface of the local node are the same.

8. A microlens on the second surface of the substrate, The image sensor according to claim 1, further comprising a photoelectric conversion region superimposed perpendicularly on the microlens.

9. The substrate further includes a transmission gate electrode arranged adjacent to one side of the substrate, The image sensor according to claim 1, characterized in that the transmission gate electrode is disposed between the short element isolation film and the isolation pattern.

10. In a plan view, the multiple local nodes are arranged spaced apart in a first direction parallel to the upper surface of the substrate and in a second direction intersecting the first direction. Local wiring is arranged between the separated local nodes. The image sensor according to claim 1, characterized in that the local wiring and the local node include polysilicon doped with a dopant of the same polarity.

11. A substrate including a first surface and a second surface facing the first surface, A separation pattern is disposed within the substrate and defines a first sensing region and a second sensing region. A short element isolation film is arranged adjacent to the first surface, A local node arranged on the short element isolation film, The short element isolation film comprises a node doping region positioned in contact with the aforementioned short element isolation film, The local node is located between the adjacent and separated separation patterns. The aforementioned local node includes polysilicon, The upper surface of the short element isolation film is in contact with the lower surface of the local node. An image sensor characterized in that the node doping region and the local node are electrically connected.

12. Grounding node on the separation pattern, The present invention further includes an intervening doping region in contact with the grounding node, The image sensor according to claim 11, characterized in that the grounding node and the intervening doping region contain polysilicon.

13. The local node and the node doping region contain polysilicon doped with a dopant of the same polarity. The image sensor according to claim 12, characterized in that the ground node and the intervening doping region contain polysilicon doped with a dopant of the same polarity.

14. In a plan view, the multiple local nodes are arranged spaced apart in a first direction parallel to the upper surface of the substrate and in a second direction intersecting the first direction. The image sensor according to claim 11, characterized in that local wiring is arranged between the separated local nodes.

15. A photoelectric conversion region provided within the substrate and positioned between the separation patterns, The system further includes a source-follower gate provided on the photoelectric conversion region, The image sensor according to claim 14, characterized in that the local wiring and the source follower gate are connected.

16. The image sensor according to claim 14, characterized in that the local wiring is superimposed on the separation pattern in at least a portion thereof.

17. The image sensor according to claim 11, characterized in that the upper surface of the local node and the first surface of the substrate are coplane.

18. The image sensor according to claim 11, characterized in that the level of the first surface is between the level of the upper surface of the local node and the level of the lower surface of the local node.

19. The local node includes an intermediate lower surface at a level higher than the level of the lower surface of the local node, The image sensor according to claim 11, characterized in that the intermediate lower surface is in contact with the node doping region.

20. A substrate having a first surface and a second surface opposite to the first surface, A separation pattern defining a sensing region within the substrate, A photoelectric conversion region provided within the aforementioned substrate, A short element isolation film adjacent to the first surface of the substrate, A transmission gate electrode is disposed adjacent to the first surface of the substrate, A local node arranged on the short element isolation film, A node doping area located adjacent to the local node, A color filter is arranged on the second surface of the substrate corresponding to the sensing area, The color filter comprises a microlens on the aforementioned color filter, The local node is located between the adjacent and separated separation patterns. The aforementioned local node includes polysilicon, The upper surface of the short element isolation film is in contact with the lower surface of the local node. An image sensor characterized in that the level of the lower surface of the node doping region is between the level of the lower surface of the local node and the level of the lower surface of the short element isolation film.

Images