Patent Description:
<CIT> relates to a solid-state image pickup element. <CIT> relates to image sensors, and more specifically to a pixel cell that includes multiple photodiodes. <NUM> With the development of computer and communications industries, demand for high-efficiency image sensor has been increased. Such image sensors are used in various fields, such as digital cameras, camcorders, personal communications systems, game components, monitors, medical micro camera, robots, etc..

In image sensors, in addition to the visible light detection element that receives visible light and converts it into the corresponding image signal, light detection elements for other wavelength ranges may also be disposed for providing image capture and other additional functions. For example, it can be used to sense distance and/or depth for 3D images, augmented reality (AR) and other related applications. Therefore, how to improve light sensitivity and quantum efficiency (QE) of the light detection units corresponding to visible light and other wavelength ranges in the image sensor through the design of structures, materials, and/or processes is a continuous issue for those in the related fields.

An image sensor, as recited in claim <NUM>, is provided in the present invention. A visible light detection structure and an infrared light detection structure are disposed within the same pixel region for improving light sensitivity, quantum efficiency, and other related properties of the image sensor.

According to an embodiment of the present invention, an image sensor is provided. The image sensor includes a semiconductor substrate, a first isolation structure, at least one visible light detection structure, and at least one infrared light detection structure. The semiconductor substrate has a first surface and a second surface opposite to the first surface in a vertical direction. The first isolation structure is disposed in the semiconductor substrate for defining pixel regions in the semiconductor substrate. The visible light detection structure and the infrared light detection structure are disposed in the semiconductor substrate, and the visible light detection structure and the infrared light detection structure are disposed within one of the pixel regions. A first portion of the visible light detection structure is disposed between the infrared light detection structure and the second surface of the semiconductor substrate in the vertical direction.

The present invention has been particularly shown and described with respect to certain embodiments and specific features thereof. The embodiments set forth herein below are to be taken as illustrative rather than limiting. It should be readily apparent to those of ordinary skill in the art that various changes and modifications in form and detail may be made.

Before the further description of the preferred embodiment, the specific terms used throughout the text will be described below.

The terms "on," "above," and "over" used herein should be interpreted in the broadest manner such that "on" not only means "directly on" something but also includes the meaning of "on" something with an intermediate feature or a layer therebetween, and that "above" or "over" not only means the meaning of "above" or "over" something but can also include the meaning it is "above" or "over" something with no intermediate feature or layer therebetween (i.e., directly on something).

The ordinal numbers, such as "first", "second", etc., used in the description and the claims are used to modify the elements in the claims and do not themselves imply and represent that the claim has any previous ordinal number, do not represent the sequence of some claimed element and another claimed element, and do not represent the sequence of the manufacturing methods, unless an addition description is accompanied. The use of these ordinal numbers is only used to make a claimed element with a certain name clear from another claimed element with the same name.

The term "forming" or the term "disposing" are used hereinafter to describe the behavior of applying a layer of material to the substrate. Such terms are intended to describe any possible layer forming techniques including, but not limited to, thermal growth, sputtering, evaporation, chemical vapor deposition, epitaxial growth, electroplating, and the like.

Please refer to <FIG> is a schematic drawing illustrating an image sensor <NUM> according to a first embodiment of the present invention. As shown in <FIG>, the image sensor <NUM> includes a semiconductor substrate <NUM>, a first isolation structure <NUM>, at least one infrared light detection structure PD1, and at least one visible light detection structure PD2. The semiconductor substrate <NUM> has a first surface S1 and a second surface S2 opposite to the first surface S1 in a vertical direction (such as a first direction D1 shown in <FIG>). The first isolation structure <NUM> is disposed in the semiconductor substrate <NUM> for defining pixel regions PX in the semiconductor substrate <NUM>. The visible light detection structure PD2 and the infrared light detection structure PD1 are disposed in the semiconductor substrate <NUM>, and the visible light detection structure PD2 and the infrared light detection structure PD1 are disposed within one of the pixel regions PX. A first portion P1 of the visible light detection structure PD2 is disposed between the infrared light detection structure PD1 and the second surface S2 of the semiconductor substrate <NUM> in the first direction D1.

In other words, the infrared light detection structure PD1 and the visible light detection structure PD2 may be disposed in the same semiconductor substrate <NUM> and located within the same pixel region PX, and a part of the visible light detection structure PD2 may overlap the infrared light detection structure PD1 in the first direction D1 for enhancing the light sensitivity or the quantum efficiency (QE) of the infrared light detection structure PD1 while the dimension of each of the pixel regions PX is limited (such as a condition where the dimension of each pixel region PX has to be reduced relatively for increasing the total resolution of the image sensor <NUM>).

In some embodiments, the first direction D1 described above may be regarded as a thickness direction of the semiconductor substrate <NUM>. The second surface S2 may be regarded as a light-incident surface or a side facing a light source, and the first surface may be regarded as a side facing away from the light source. A horizontal direction orthogonal to the first direction D1 (such as a second direction D2 shown in <FIG>) may be substantially parallel with the first surface S1 of the semiconductor substrate <NUM> and/or the second surface S2 of the semiconductor substrate <NUM>, but not limited thereto. In the image sensor <NUM>, each of the pixel regions PX may be surrounded by the first isolation structure <NUM> in a horizontal direction (such as the second direction D2 described above and other directions orthogonal to the first direction D1). In some embodiments, the image sensor <NUM> may include a plurality of the infrared light detection structures PD1 and a plurality of the visible light detection structures PD2, and at least one of the pixel regions PX may have the infrared light detection structure PD1 and the visible light detection structure PD2 disposed therein. For example, in some embodiments, one infrared light detection structure PD1 and one visible light detection structure PD2 may be disposed in each pixel region PX, and at least some of the pixel regions PX may be used to detecting different colors of visible light, respectively, but not limited thereto.

In some embodiments, the visible light detection structure PD2 may include a visible light photodiode or a portion of a visible light photodiode, and the infrared light detection structure PD1 may include an infrared photodiode or a portion of an infrared photodiode, but not limited thereto. In some embodiments, the infrared light detection structure PD1 may include other structures (apart from photodiodes) capable of converting infrared light into corresponding electrical signals, and the visible light detection structure PD2 may include other structures (apart from photodiodes) capable of converting visible light into corresponding electrical signals. In addition, in some embodiments, a material composition of the infrared light detection structure PD1 may be different from a material composition of the visible light detection structure PD2 for enhancing the light sensitivity and/or the QE of the infrared light detection structure PD1.

For example, the infrared light detection structure PD1 may include an epitaxial structure ES disposed in the semiconductor substrate <NUM>, and the visible light detection structure PD2 may include a doped region DR disposed in the semiconductor substrate <NUM>, but not limited thereto. In some embodiments, the semiconductor substrate <NUM> may include a silicon substrate, a silicon-containing substrate, or a substrate made of other suitable semiconductor materials, and the doped region DR may be formed by performing a doping process (such as an ion implantation process or other suitable doping approaches) to the semiconductor substrate <NUM>, and the doped region DR may include a part of the semiconductor substrate <NUM> (such as silicon) and a dopant implanted into the semiconductor substrate <NUM> by the doping process described above. In other words, the doped region DR may include a material (such as silicon) identical to a material of the semiconductor substrate <NUM>, and the material may be different from the material of the epitaxial structure ES. Additionally, in some embodiments, the epitaxial structure ES may include epitaxial germanium, silicon germanium, III-V compound semiconductor epitaxial material (such as epitaxial indium gallium arsenide (InGaAs), gallium arsenide (GaAs), and gallium phosphide (GaP)), or a material having an infrared light absorption (or absorption rate) higher than that of the material of the semiconductor substrate <NUM>. Accordingly, even though the infrared light detection structure PD1 and the visible light detection structure PD2 are disposed in the same semiconductor substrate <NUM> and located within the same pixel region PX, and the first portion P1 of the visible light detection structure PD2 overlaps the infrared light detection structure PD1 in the first direction D1 and is located between the light-incident surface (such as the second surface S2) and the infrared light detection structure PD1 in the first direction D1, the infrared light detection structure PD1 in the image sensor <NUM> may still have a great photoelectric conversion performance by forming the infrared light detection structure PD1 with the epitaxial material having a relatively higher infrared light absorption rate for improving the light sensitivity and/or the QE of the infrared light detection structure PD1.

In some embodiments, the image sensor <NUM> may further include a second isolation structure <NUM> disposed in the semiconductor substrate <NUM> and located in the pixel regions PX, but not limited thereto. In some embodiments, a second portion P2 of the visible light detection structure PD2 may disposed between the first isolation structure <NUM> and the infrared light detection structure PD1 located in the same pixel region PX in a horizontal direction (such as the second direction D2), the second portion P2 of the visible light detection structure PD2 may be elongated towards the first surface S1 in the first direction D1, and the second portion P2 of the visible light detection structure PD2 may be directly connected with the first portion P1 of the visible light detection structure PD2, but not limited thereto. In addition, in at least one of the pixel regions PX, a part of the second isolation structure <NUM> may be disposed between the infrared light detection structure PD1 and the second portion P2 of the visible light detection structure PD2 in the second direction D2 for reducing the interference between the infrared light detection structure PD1 and the visible light detection structure PD2 in the same pixel region PX. In some embodiments, the first isolation structure <NUM> and the second isolation structure <NUM> may respectively include a single layer or multiple layers of insulation materials, such as silicon oxide, silicon nitride, or other suitable insulation materials.

In some embodiments, a part of the first isolation structure <NUM> may penetrate through the semiconductor substrate <NUM> in the first direction D1, and the first portion P1 of the visible light detection structure PD2 may be disposed between the second surface S2 of the semiconductor substrate <NUM> and the second isolation structure <NUM> in the first direction D1, but not limited thereto. In some embodiments, a length of the second isolation structure <NUM> in the first direction D1 may be greater than or equal to a length of the infrared light detection structure PD1 in the first direction D1, and the length of the second isolation structure <NUM> in the first direction D1 may be less than a length of the first isolation structure <NUM> in the first direction D1 for reducing the interference between the infrared light detection structure PD1 and the visible light detection structure PD2 located in the same pixel region PX in the second direction D2 by the second isolation structure <NUM> and avoiding the negative influence of a second isolation structure <NUM> extending to the visible light detection structure PD2 on the visible light detection structure PD2.

In some embodiments, the image sensor <NUM> may further include at least one first gate electrode G1, at least one second gate electrode G2, a reflective structure <NUM>, at least one contact structure <NUM>, at least one contact structure <NUM>, at least one reflective layer <NUM>, an interconnection structure <NUM>, and a dielectric layer <NUM>, but not limited thereto. The first gate electrode G1, the second gate electrode G2, the reflective structure <NUM>, the contact structure <NUM>, the contact structure <NUM>, the reflective layer <NUM>, the interconnection structure <NUM>, and the dielectric layer <NUM> may be disposed on the first surface S1 of the semiconductor substrate <NUM>. In some embodiments, the first gate electrode G1 may be disposed corresponding to the infrared light detection structure PD1, the second gate electrode G2 may be disposed corresponding to the visible light detection structure PD2, the first gate electrode G1 may be a gate electrode of a transistor (not shown in <FIG>) electrically connected with the infrared light detection structure PD1, and the second gate electrode G2 may be a gate electrode of a transistor (not shown in <FIG>) electrically connected with the visible light detection structure PD2, but not limited thereto.

In the invention, the reflective structure <NUM> may be an electrically floating conductive structure. In other words, the reflective structure <NUM> may be not electrically connected with other parts. A part of the reflective structure <NUM> may be disposed on the first isolation structure <NUM> in the first direction D1, and another part of the reflective structure <NUM> may be disposed between the first gate electrode G1 and the second gate electrode G2 for reducing the light interference between the pixel regions PX adjacent to each other, the light interference between the infrared light detection structure PD1 and the visible light detection structure PD2 located in the same pixel region PX, and/or increasing the light sensitivity of the infrared light detection structure PD1, but not limited thereto. Additionally, in some embodiments, when the image sensor <NUM> is viewed in the first direction D1 (such as viewing the image sensor <NUM> at a side of the second surface S2), the reflective structure <NUM> disposed between the first gate electrode G1 and the second gate electrode G2 may be disposed on the second isolation structure <NUM> in the first direction D1, and the reflective structure <NUM> disposed between the first gate electrode G1 and the second gate electrode G2 may overlap at least a part of the second isolation structure <NUM> in the first direction D1. Therefore, the reflective structure <NUM> may be not directly in contact with the semiconductor substrate <NUM> in order to reduce the electrical influence of the reflective structure <NUM> on the infrared light detection structure PD1 and the visible light detection structure PD2.

In some embodiments, the contact structure <NUM> may be disposed on and electrically connected with the first gate electrode G1, the contact structure <NUM> may be disposed on and electrically connected with the second gate electrode G2. The reflective structure <NUM>, the contact structure <NUM>, and the contact structure <NUM> may be formed concurrently by the same manufacturing process for process simplification, and the material compositions of the reflective structure <NUM>, the contact structure <NUM>, and the contact structure <NUM> may be identical to one another accordingly, but not limited thereto. In some embodiments, the reflective layer <NUM> may be disposed corresponding to the infrared light detection structure PD1 in the first direction D1, the infrared light detection structure PD1 may be disposed between the reflective layer <NUM> and the first portion P1 of the visible light detection structure PD2 in the first direction D1, and the first gate electrode G1 may be located between the infrared light detection structure PD1 and the reflective layer <NUM> in the first direction D1, but not limited thereto. In addition, the reflective layer <NUM> and at least a part of the interconnection structure <NUM> may be formed concurrently by the same manufacturing process for process simplification, and the material composition of the reflective layer <NUM> may be identical to the material composition of at least a part of the interconnection structure <NUM> accordingly, but not limited thereto. In some embodiments, the reflective layer <NUM> may be an electrically floating conductive layer for reducing the negative influence of the reflective layer <NUM> with relatively larger range on electrical properties of other components (such as the transistor corresponding to the first gate electrode G1 and/or the transistor corresponding to the second gate electrode G2), but not limited thereto.

In some embodiments, the image sensor <NUM> may include a plurality of the first gate electrodes G1, a plurality of the second gate electrodes G2, and a plurality of the reflective layers <NUM> disposed corresponding to the pixel regions PX, respectively, but not limited thereto. The first gate electrode G1 and the second gate electrode G2 described above may respectively include non-metallic electrically conductive materials (such as doped polysilicon) or metallic electrically conductive materials, such as a metal gate structure formed with a work function layer and a low resistivity layer stacked with each other, but not limited thereto. The reflective structure <NUM>, the contact structure <NUM>, the contact structure <NUM>, the reflective layer <NUM>, and the interconnection structure <NUM> described above may respectively include a barrier layer (not shown) and an electrically conductive material (not shown) disposed on the barrier layer, but not limited thereto. The barrier layer described above may include titanium nitride, tantalum nitride, or other suitable barrier materials, and the electrically conductive material described above may include a material with relatively lower electrical resistivity, such as tungsten, aluminum, copper, titanium aluminide, and titanium, but not limited thereto. In addition, the dielectric layer <NUM> may include high dielectric constant (high-k) dielectric material or other suitable dielectric material (such as silicon oxide).

In some embodiments, the image sensor <NUM> may further include an anti-reflection layer <NUM>, a patterned isolation structure <NUM>, a plurality of color filter units <NUM>, and a plurality of microlenses <NUM>, but not limited thereto. The anti-reflection layer <NUM>, the patterned isolation structure <NUM>, the color filter units <NUM>, and the microlenses <NUM> may be disposed on the second surface S2 of the semiconductor substrate <NUM>. The color filter units <NUM> and the patterned isolation structure <NUM> may be disposed on the anti-reflection layer <NUM>, and the microlenses <NUM> may be disposed on the color filter units <NUM>. In some embodiments, the patterned isolation structure <NUM> may be disposed between the color filter units <NUM> adjacent to each other for reducing the light interference between the color filter units <NUM> adjacent to each other, and the patterned isolation structure <NUM> may include a metal material or a material with a relatively higher optical density (OD).

Each of the color filter units <NUM> may be disposed corresponding to one of the pixel regions PX in the first direction D1. For example, in some embodiments, the color filter units <NUM> may include a first color filter unit 70A, a second color filter unit 70B, and a third color filter unit 70C of different colors and disposed adjacent to one another, and the pixel regions PX may include a first pixel region PX1, a second pixel region PX2, and a third pixel region PX3 disposed corresponding to the first color filter unit 70A, the second color filter unit 70B, and the third color filter unit 70C, respectively. Therefore, in some embodiments, the infrared light detection structures PD1 may be disposed in the pixel regions PX corresponding to different colors respectively for increasing the amount of the infrared light detection structures PD1 disposed in the image sensor <NUM> and/or improving contrast and/or sharpness of the image data generated by the pixel regions PX corresponding to different colors.

Please refer to <FIG> and <FIG>. <FIG> is a schematic drawing illustrating the infrared light detection structure PD1 according to an embodiment of the present invention. As shown in <FIG> and <FIG>, in some embodiments, the infrared light detection structure PD1 may include the epitaxial structure ES formed with a doped epitaxial layer <NUM>, an intrinsic epitaxial layer <NUM>, and a doped epitaxial layer <NUM>. The doped epitaxial layer <NUM> and the doped epitaxial layer <NUM> may be a p-type doped epitaxial layer (such as a p-type heavily doped epitaxial germanium layer) and an n-type doped epitaxial layer (such as an n-type heavily doped epitaxial germanium layer), respectively, for forming a PIN photodiode with the intrinsic epitaxial layer <NUM> (such as an epitaxial germanium layer without being intentionally doped), but not limited thereto. In some embodiments, a doped region <NUM> (such as a p-type lightly doped epitaxial germanium region) may surround the doped epitaxial layer <NUM>, a patterned insulation layer <NUM> may be disposed on the doped region <NUM> and the doped epitaxial layer <NUM>, and a conductive layer <NUM> may contact and be electrically connected with the doped epitaxial layer <NUM>, but not limited thereto. In some embodiments, the conductive layer <NUM> may be used to electrically connect the PIN photodiode described above and the transistor corresponding to the first gate electrode G1 described above, and the doped region <NUM> may be used to reduce the negative influence of the interface defect between the doped epitaxial layer <NUM> and the patterned insulation layer <NUM> on the electrical properties of the PIN photodiode, but not limited thereto. It is worth noting that the structure of the infrared light detection structure PD1 in the present invention is not limited to the condition illustrated in <FIG> and the infrared light detection structure PD1 with other suitable structural design may be applied according to some design considerations.

Please refer to <FIG> and <FIG>. <FIG> is a schematic circuit diagram corresponding to one pixel region PX in the image sensor according to an embodiment of the present invention. As shown in <FIG> and <FIG>, in some embodiments, a circuit structure corresponding to one pixel region PX may include the infrared light detection structure PD1, the visible light detection structure PD2, a transistor T1, a transistor T2, a transistor T3, a transistor T4, and a transistor T5, but not limited thereto. In some embodiments, a source/drain terminal of the transistor T1 may be electrically connected with the infrared light detection structure PD1, another source/drain terminal of the transistor T1 may be electrically connected with a source/drain terminal of the transistor T3 and a source/drain terminal of the transistor T4, and the first gate electrode G1 described above may be a gate electrode in the transistor T1, but not limited thereto. In addition, a source/drain terminal of the transistor T2 may be electrically connected with the visible light detection structure PD2, another source/drain terminal of the transistor T2 may be electrically connected with another source/drain terminal of the transistor T3 and a gate electrode of the transistor T5, and the second gate electrode G2 described above may be a gate electrode in the transistor T2, but not limited thereto. In some embodiments, the transistor T3 may be regarded as a switch transistor, the transistor T4 may be regarded as a reset transistor because another source/drain terminal of the transistor T4 may be connected with a reset signal source, and the transistor T5 may be regarded as a readout transistor, but not limited thereto. It is worth noting that the circuit structure corresponding to the pixel region PX in the present invention is not limited to the condition illustrated in <FIG> and other suitable circuit structure may be applied according to some design considerations.

Please refer to <FIG> and <FIG>. <FIG> are schematic drawings illustrating a manufacturing method of an image sensor according to an embodiment of the present invention, wherein <FIG> is a schematic drawing in a step subsequent to <FIG>, <FIG> is a schematic drawing in a step subsequent to <FIG>, <FIG> is a schematic drawing in a step subsequent to <FIG>, <FIG> is a schematic drawing in a step subsequent to <FIG>, <FIG> is a schematic drawing in a step subsequent to <FIG>, and <FIG> may be regarded as a schematic drawing in a step subsequent to <FIG>, but not limited thereto. As shown in <FIG>, the manufacturing method of the image sensor <NUM> in this embodiment may include the following steps. At least one infrared light detection structure PD1 is formed in the semiconductor substrate <NUM>. The first isolation structure <NUM> is formed in the semiconductor substrate <NUM> for defining the pixel regions PX in the semiconductor substrate <NUM>. At least one visible light detection structure PD2 is formed in the semiconductor substrate <NUM>. The semiconductor substrate <NUM> has the first surface S1 and the second surface S2 opposite to the first surface S1 in a vertical direction (such as the first direction D1). The visible light detection structure PD2 and the infrared light detection structure PD1 are located within one of the pixel regions PX, and the first portion P1 of the visible light detection structure PD2 is disposed between the infrared light detection structure PD1 and the second surface S2 of the semiconductor substrate <NUM> in the first direction D1.

Specifically, the manufacturing method of the image sensor <NUM> in this embodiment may include but is not limited to the following steps. As shown in <FIG>, a plurality of trenches TR may be formed from a side of the first surface S1 of the semiconductor substrate <NUM>. Subsequently, as shown in <FIG>, an epitaxial process <NUM> may be performed for forming the epitaxial structures ES on the semiconductor substrate <NUM>, and each of the trenches TR may be filled with the epitaxial structure ES. The epitaxial process <NUM> may include an epitaxial growth process or other manufacturing approaches for forming the epitaxial structures ES. In addition, the epitaxial structure ES may include a plurality of epitaxial layers (such as the epitaxial layers shown in <FIG> described above) disposed stacked with one another, but not limited thereto. The photoelectric conversion performance of the infrared light detection structure PD1 may be enhanced by forming the infrared light detection structure PD1 with the material having a relatively high infrared light absorption rate because the infrared light detection structure PD1 may be formed in the trench TR by the epitaxial process <NUM>, and the material composition of the infrared light detection structure PD1 may be different from the material composition of the semiconductor substrate <NUM> accordingly.

Subsequently, as shown in <FIG>, the first isolation structure <NUM> and the second isolation structure <NUM> may be formed in the semiconductor substrate <NUM> for defining the pixel regions PX in the semiconductor substrate <NUM>. In some embodiments, the first isolation structure <NUM> and the second isolation structure <NUM> may be respectively elongated towards the second surface S2 from the first surface S1 of the semiconductor substrate <NUM>. A length L3 of the first isolation structure <NUM> in the first direction D1 may be greater than a length L2 of the second isolation structure <NUM> in the first direction D1, and the length L2 of the second isolation structure <NUM> in the first direction D1 may be greater than or equal to a length L1 of the infrared light detection structure PD1 in the first direction D1, but not limited thereto.

Subsequently, as shown in <FIG>, the visible light detection structure PD2 may be formed in the semiconductor substrate <NUM>, and the first gate electrode G1, the second gate electrode G2, and other related components (such as the transistors described above) may be formed on the first surface S1 of the semiconductor substrate <NUM>. In some embodiments, the visible light detection structure PD2 may include the doped region DR in the semiconductor substrate <NUM>, the doped region DR may be formed by performing a doping process to the semiconductor substrate <NUM>, and the doped region DR may include a part of the semiconductor substrate <NUM> (such as silicon) and a dopant implanted into the semiconductor substrate <NUM> by the doping process described above accordingly. In some embodiments, the doped region DR may include one or a plurality of doped regions with different conductivity types (such as an n-type doped region and/or a p-type doped region), the dopant used in the doping process may include phosphorus (P), arsenic (As) or other suitable dopants, and the implantation dose used in the doping process may range from 1E+<NUM> ion/cm<NUM> to 1E+<NUM> ion/cm<NUM>, but not limited thereto. Additionally, in some embodiments, because the infrared light detection structure PD1 and the second isolation structure <NUM> may be formed before the step of forming the visible light detection structure PD2, the doping process for forming the visible light detection structure PD2 may be performed to the first surface S1 of the semiconductor substrate <NUM> and/or the second surface S2 of the semiconductor substrate <NUM> for forming the visible light detection structure PD2 occupying the required range and reducing the negative influence of the doping process on the infrared light detection structure PD1.

Subsequently, as shown in <FIG> and <FIG>, the reflective structure <NUM>, the contact structure <NUM>, the contact structure <NUM>, the reflective layer <NUM>, the interconnection structure <NUM>, and the dielectric layer <NUM> may be formed on the first surface S1 of the semiconductor substrate <NUM>, and the anti-reflection layer <NUM> and the patterned isolation structure <NUM> may be formed on the second surface S2 of the semiconductor substrate <NUM>. In some embodiments, a thinning process may be performed to the second surface S2 of the semiconductor substrate <NUM> before the step of forming the anti-reflection layer <NUM> for removing a part of the semiconductor substrate <NUM> and making the semiconductor substrate <NUM> thinner, and the first isolation structure <NUM> may penetrate through the semiconductor substrate <NUM> in the first direction D1 after the thinning process, but not limited thereto. Subsequently, as shown in <FIG> and <FIG>, the color filter units <NUM> and the microlenses <NUM> may be formed for forming the image sensor <NUM> described above. In some embodiments, the second surface S2 may be regarded as a light-incident surface or a side facing a light source. The infrared light detection structure PD1 and the visible light detection structure PD2 may be disposed between the second surface S2 and the circuit structure (such as the transistors corresponding to the first gate electrode G1 and the second gate electrode G2 and the interconnection structure <NUM>) in the first direction D1, and the image sensor <NUM> may be regarded as a backside illumination image sensor accordingly, but not limited thereto. In addition, the manufacturing method of the image sensor <NUM> in this embodiment is not limited to the condition illustrated in <FIG> described above and the image sensor <NUM> may be formed by other suitable manufacturing approaches according to some design considerations.

The following description will detail the different embodiments of the present invention. To simplify the description, identical components in each of the following embodiments are marked with identical symbols. For making it easier to understand the differences between the embodiments, the following description will detail the dissimilarities among different embodiments and the identical features will not be redundantly described.

Please refer to <FIG> is a schematic drawing illustrating an image sensor <NUM> according to a second embodiment of the present invention. As shown in <FIG>, in some embodiments, the reflective layer <NUM> may be elongated in the horizontal direction for being disposed corresponding to the infrared light detection structure PD1 and the visible light detection structure PD2 disposed within the same pixel region PX, and the visible light detection structure PD2 may be disposed between the reflective layer <NUM> and the second surface S2 of the semiconductor substrate <NUM> in the first direction D1 accordingly. The reflective layer <NUM> may be used to increase the amount of light entering the infrared light detection structure PD1 and the visible light detection structure PD2, and the infrared light detection performance and/or the visible light detection performance of the image sensor <NUM> may be improved accordingly.

To summarize the above descriptions, according to the image sensor in the present invention, the visible light detection structure and the infrared light detection structure may be disposed within the same pixel region in the semiconductor substrate for improving the infrared light sensitivity and the quantum efficiency of the infrared light detection in the image sensor.

Claim 1:
An image sensor (<NUM>; <NUM>), comprising:
a semiconductor substrate (<NUM>) having a first surface (S1) and a second surface (S2) opposite to the first surface (S1) in a vertical direction (D1);
a first isolation structure (<NUM>) disposed in the semiconductor substrate (<NUM>) for defining pixel regions (PX) in the semiconductor substrate (<NUM>);
at least one visible light detection structure (PD2) disposed in the semiconductor substrate (<NUM>);
at least one infrared light detection structure (PD1) disposed in the semiconductor substrate (<NUM>), wherein the at least one visible light detection structure (PD2) and the at least one infrared light detection structure (PD1) are disposed within one of the pixel regions (PX), and a first portion (P1) of the at least one visible light detection structure (PD2) is disposed between the at least one infrared light detection structure (PD1) and the second surface (S2) of the semiconductor substrate (<NUM>) in the vertical direction (D1);
wherein the image sensor further comprises:
a first gate electrode (G1) disposed on the first surface (S1) of the semiconductor substrate (<NUM>) and disposed corresponding to the at least one infrared light detection structure (PD1); and
a second gate electrode (G2) disposed on the first surface (S1) of the semiconductor substrate (<NUM>) and disposed corresponding to the at least one visible light detection structure (PD2); and characterised by
a reflective structure (<NUM>), in particular an electrically floating conductive structure, disposed on the first surface (S1) of the semiconductor substrate (<NUM>), wherein a part of the reflective structure (<NUM>) is disposed on the first isolation structure (<NUM>) in the vertical direction (D1), and another part of the reflective structure (<NUM>) is disposed between the first gate electrode (G1) and the second gate electrode (G2).