Image sensor structure

Abstract

The invention discloses an image sensor structure which comprises a substrate, a light detector and a transparent capacitor. The light detector is located in the substrate. The transparent capacitor is located right above the light detector. The transparent capacitor has a first upper surface and a second upper surface. The second upper surface is higher than the first upper surface.

Description

Technical Field

[0001] The present invention relates to an image sensor structure, and more particularly to an image sensor structure including a capacitor. Background Art

[0002] Image sensors are widely used in many modern electronic devices (such as smart phones or digital cameras, etc.). However, how to further improve the electrical performance of image sensors is an ongoing goal. Summary of the Invention

[0003] The present invention provides an image sensor structure, which can have better electrical performance.

[0004] The present invention proposes an image sensor structure, including a substrate, a photodetector, and a transparent capacitor. The photodetector is located in the substrate. The transparent capacitor is located directly above the photodetector. The transparent capacitor has a first upper surface and a second upper surface. The second upper surface is higher than the first upper surface.

[0005] According to an embodiment of the present invention, in the above image sensor structure, the photodetector is, for example, a photodiode.

[0006] According to an embodiment of the present invention, in the above image sensor structure, a first dielectric structure and a second dielectric structure may further be included. The first dielectric structure is located between the transparent capacitor and the substrate. An opening may be provided in the first dielectric structure. The opening may be located directly above the photodetector. The transparent capacitor is located in the opening and on the top surface of the first dielectric structure. The second dielectric structure is located on the transparent capacitor and the first dielectric structure.

[0007] According to an embodiment of the present invention, in the above image sensor structure, the transparent capacitor may include a first transparent electrode layer, a transparent dielectric layer, and a second transparent electrode layer stacked in sequence on the first dielectric structure.

[0008] According to an embodiment of the present invention, in the above image sensor structure, the first transparent electrode layer may conformally be located in the opening and on the top surface of the first dielectric structure. The transparent dielectric layer may conformally be located on the first transparent electrode layer. The second transparent electrode layer may conformally be located on the transparent dielectric layer.

[0009] According to an embodiment of the present invention, in the above image sensor structure, the light transmittance of the first transparent electrode layer may be 80% to 95%. The light transmittance of the transparent dielectric layer may be 80% to 95%. The light transmittance of the second transparent electrode layer may be 80% to 95%.

[0010] According to an embodiment of the present invention, in the above image sensor structure, the light transmittance of the first transparent electrode layer may be 85% to 90%. The light transmittance of the transparent dielectric layer may be 90% to 95%. The light transmittance of the second transparent electrode layer may be 85% to 90%.

[0011] According to an embodiment of the present invention, in the above image sensor structure, a first inner connection structure and a second inner connection structure may further be included. The first inner connection structure is located in the first dielectric structure. The first inner connection structure may be electrically connected to the first transparent electrode layer. The second inner connection structure is located in the second dielectric structure. The second inner connection structure may be electrically connected to the second transparent electrode layer.

[0012] According to an embodiment of the present invention, in the above image sensor structure, the first inner connection structure may be connected to a portion of the first transparent electrode layer that is directly above the top surface of the first dielectric structure. The second inner connection structure may be connected to a portion of the second transparent electrode layer that is directly above the top surface of the first dielectric structure.

[0013] According to an embodiment of the present invention, in the above image sensor structure, a color filter layer and a microlens may further be included. The color filter layer is located on the second dielectric structure. The microlens is located on the color filter layer.

[0014] Based on the above, in the image sensor structure proposed by the present invention, the transparent capacitor is directly above the photodetector. The transparent capacitor has a first upper surface and a second upper surface. The second upper surface is higher than the first upper surface. Therefore, the transparent capacitor can have a larger capacitance value, thereby reducing the thermal noise (KTC noise). In addition, since the transparent capacitor directly above the photodetector can function as a light pipe, oblique light can be reflected to the photodetector, thereby improving the quantum efficiency (QE). Since the image sensor structure proposed by the present invention can reduce the thermal noise and improve the quantum efficiency, the image sensor structure proposed by the present invention can have better electrical performance.

[0015] To make the above features and advantages of the present invention more obvious and understandable, specific embodiments are hereinafter given and described in detail in conjunction with the accompanying drawings as follows. Brief Description of the Drawings

[0016] Figures 1A to 1H It is a cross-sectional view of the manufacturing process of the image sensor structure according to some embodiments of the present invention.

[0017] Symbol Description

[0018] 10: Image sensor structure

[0019] 100: Substrate

[0020] 102: Photodetector

[0021] 104, 110: Transistor

[0022] 106, 112: Gate

[0023] 108, 114: Gate dielectric layer

[0024] 116, 144: Dielectric structure

[0025] 118, 120, 138: Interconnection structure

[0026] 122: Patterned photoresist layer

[0027] 124, 128: Transparent electrode material layer

[0028] 124a, 128a: Transparent electrode layer

[0029] 126: Transparent dielectric material layer

[0030] 126a: Transparent dielectric layer

[0031] 130: Transparent capacitor

[0032] 132, 142: Dielectric layer

[0033] 134: Via hole

[0034] 136, 140: Conductor

[0035] 146: Color filter layer

[0036] 148: Microlens

[0037] OP1: Opening

[0038] S1: Top surface

[0039] S2, S3: Upper surface Detailed implementation manners

[0040] Examples are listed below and described in detail with reference to the accompanying drawings. However, the provided examples are not intended to limit the scope covered by the present invention. For ease of understanding, the same components will be denoted by the same reference numerals in the following description. In addition, the drawings are for illustrative purposes only and are not drawn to the original scale. In fact, for the sake of clarity of discussion, the dimensions of various features can be increased or decreased arbitrarily.

[0041] Figures 1A to 1H It is a manufacturing process cross-sectional view of an image sensor structure according to some embodiments of the present invention.

[0042] Please refer toFigure 1A , a substrate 100 is provided. In some embodiments, the substrate 100 can be a semiconductor substrate, such as a silicon substrate. Additionally, a photodetector 102 can be formed in the substrate 100. In some embodiments, the photodetector 102 is, for example, a photodiode. Additionally, although not shown in the figure, other necessary components (such as doped regions and / or isolation structures) can be present in the substrate 100, and their descriptions are omitted herein.

[0043] In some embodiments, a transistor 104 can be formed. In some embodiments, the transistor 104 can be a transfer transistor. The transistor 104 can include a gate 106 and a gate dielectric layer 108. The gate 106 is located on the substrate 100. In some embodiments, the material of the gate 106 is, for example, doped polysilicon. The gate dielectric layer 108 is located between the gate 106 and the substrate 100. In some embodiments, the material of the gate dielectric layer 108 is, for example, silicon oxide. Additionally, although not shown in the figure, the transistor 104 can also include other necessary components (such as doped regions), and their descriptions are omitted herein.

[0044] In some embodiments, a transistor 110 can be formed. The transistor 110 can include a gate 112 and a gate dielectric layer 114. The gate 112 is located on the substrate 100. In some embodiments, the material of the gate 112 is, for example, doped polysilicon. The gate dielectric layer 114 is located between the gate 112 and the substrate 100. In some embodiments, the material of the gate dielectric layer 114 is, for example, silicon oxide. Additionally, although not shown in the figure, the transistor 110 can also include other necessary components (such as doped regions), and their descriptions are omitted herein.

[0045] In some embodiments, a dielectric structure 116 can be formed on the substrate 100. The dielectric structure 116 can cover the transistor 104 and the transistor 110. In some embodiments, the dielectric structure 116 can be a multi-layer structure. In some embodiments, the dielectric structure 116 can be a silicon oxide layer, a silicon nitride layer, or a combination thereof.

[0046] In some embodiments, an interconnection structure 118 can be formed in the dielectric structure 116. In some embodiments, the interconnection structure 118 can be a multi-layer structure. In some embodiments, the interconnection structure 118 can include a contact, a via, a wire, or a combination thereof. In some embodiments, the material of the interconnection structure 118 is, for example, aluminum, tungsten, copper, titanium, titanium nitride, tantalum, tantalum nitride, or a combination thereof. In some embodiments, the interconnection structure 118 can be formed through an interconnection manufacturing process.

[0047] In some embodiments, an interconnect structure 120 may be formed in the dielectric structure 116. In some embodiments, the interconnect structure 120 may be a multi-layer structure. In some embodiments, the interconnect structure 120 may include contact windows, vias, wires, or combinations thereof. In some embodiments, the material of the interconnect structure 120 is, for example, aluminum, tungsten, copper, titanium, titanium nitride, tantalum, tantalum nitride, or combinations thereof. In some embodiments, the interconnect structure 120 may be formed by an interconnect fabrication process.

[0048] Please refer to Figure 1B , a patterned photoresist layer 122 may be formed on the dielectric structure 116. In some embodiments, the patterned photoresist layer 122 may be formed by a photolithography fabrication process. Then, using the patterned photoresist layer 122 as a mask, a portion of the dielectric structure 116 may be removed to form an opening OP1. Thus, an opening OP1 may be formed in the dielectric structure 116. The opening OP1 may be located directly above the photodetector 102. In some embodiments, the method for removing a portion of the dielectric structure 116 is, for example, a dry etching method.

[0049] Please refer to Figure 1C , the patterned photoresist layer 122 may be removed. In some embodiments, the method for removing the patterned photoresist layer 122 is, for example, a dry stripping method or a wet stripping method.

[0050] Next, a transparent electrode material layer 124 may be conformally formed in the opening OP1 and on the top surface S1 of the dielectric structure 116. The transparent electrode material layer 124 may be electrically connected to the interconnect structure 120. In some embodiments, the material of the transparent electrode material layer 124 is, for example, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), or indium zinc oxide (IZO). In some embodiments, the method for forming the transparent electrode material layer 124 is, for example, a chemical vapor deposition method.

[0051] Then, a transparent dielectric material layer 126 may be conformally formed on the transparent electrode material layer 124. In some embodiments, the material of the transparent dielectric material layer 126 is, for example, silicon oxide. In some embodiments, the method for forming the transparent dielectric material layer 126 is, for example, an atomic layer deposition (ALD) method.

[0052] Next, a transparent electrode material layer 128 can be conformally formed on the transparent dielectric material layer 126. In some embodiments, the material of the transparent electrode material layer 128 is, for example, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), or indium zinc oxide (IZO). In some embodiments, the method of forming the transparent electrode material layer 128 is, for example, chemical vapor deposition.

[0053] Please refer to Figure 1D , the transparent electrode material layer 128, the transparent dielectric material layer 126, and the transparent electrode material layer 124 can be patterned to form a transparent electrode layer 128a, a transparent dielectric layer 126a, and a transparent electrode layer 124a. Thus, a transparent capacitor 130 can be formed directly above the photodetector 102. The transparent capacitor 130 can include a transparent electrode layer 124a, a transparent dielectric layer 126a, and a transparent electrode layer 128a stacked in sequence on the dielectric structure 116. In some embodiments, the transparent electrode material layer 128, the transparent dielectric material layer 126, and the transparent electrode material layer 124 can be patterned by a photolithography process and an etching process.

[0054] In some embodiments, the light transmittance of the transparent electrode layer 124a can be 80% to 95%. In some embodiments, the light transmittance of the transparent electrode layer 124a can be 85% to 90%. In some embodiments, the light transmittance of the transparent dielectric layer 126a can be 80% to 95%. In some embodiments, the light transmittance of the transparent dielectric layer 126a can be 90% to 95%. In some embodiments, the light transmittance of the transparent electrode layer 128a can be 80% to 95%. In some embodiments, the light transmittance of the transparent electrode layer 128a can be 85% to 90%. In some embodiments, the material of the transparent electrode layer 124a is, for example, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), or indium zinc oxide (IZO). In some embodiments, the material of the transparent dielectric layer 126a is, for example, silicon oxide. In some embodiments, the material of the transparent electrode layer 128a is, for example, indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), or indium zinc oxide (IZO).

[0055] Please refer to Figure 1E , a dielectric layer 132 can be formed on the transparent capacitor 130 and the dielectric structure 116. The dielectric layer 132 can fill the opening OP1. In some embodiments, the material of the dielectric layer 132 is, for example, silicon oxide. In some embodiments, the method of forming the dielectric layer 132 is, for example, chemical vapor deposition.

[0056] Please refer to Figure 1F , a part of the dielectric layer 132 can be removed. In some embodiments, the method of removing a part of the dielectric layer 132 is, for example, chemical mechanical polishing.

[0057] Next, vias 134 can be formed in the dielectric layer 132. The vias 134 can be electrically connected to the transparent electrode layer 128a. In some embodiments, the material of the vias 134 is, for example, tungsten, titanium, titanium nitride, or a combination thereof. In some embodiments, the vias 134 can be formed by an interconnect manufacturing process.

[0058] Please refer to Figure 1G , a wire 136 can be formed on the dielectric layer 132. The wire 136 can be electrically connected to the via 134. Thus, an interconnect structure 138 can be formed. In this embodiment, the interconnect structure 138 can be a multi-layer structure. For example, the interconnect structure 138 can include the vias 134 and the wires 136. The vias 134 are located in the dielectric layer 132. The wires 136 are located on the vias 134 and the dielectric layer 132. In addition, a wire 140 can be formed on the dielectric layer 132. In some embodiments, the materials of the wires 136 and 140 are, for example, aluminum, tungsten, titanium, titanium nitride, or a combination thereof. In some embodiments, the wires 136 and 140 can be formed by an interconnect manufacturing process.

[0059] Please refer to Figure 1H , a dielectric layer 142 can be formed on the dielectric layer 132, the wire 136, and the wire 140. Thus, a dielectric structure 144 can be formed on the transparent capacitor 130 and the dielectric structure 116. In some embodiments, the dielectric structure 144 can be a multi-layer structure. For example, the dielectric structure 144 can include the dielectric layer 132 and the dielectric layer 142. The dielectric layer 132 is located on the transparent capacitor 130 and the dielectric structure 116. The dielectric layer 142 is located on the dielectric layer 132. In some embodiments, the material of the dielectric layer 142 is, for example, silicon oxide. In some embodiments, the formation method of the dielectric layer 142 is, for example, chemical vapor deposition.

[0060] Next, a color filter layer 146 can be formed on the dielectric structure 144. In some embodiments, the color filter layer 146 can be a red filter layer, a green filter layer, or a blue filter layer. Then, a microlens 148 can be formed on the color filter layer 146.

[0061] Hereinafter, the image sensor structure 10 of the above embodiment will be described through Figure 1H . In addition, although the formation method of the image sensor structure 10 is described by taking the above method as an example, the present invention is not limited thereto.

[0062] Please refer to Figure 1H , the image sensor structure 10 includes a substrate 100, a photodetector 102, and a transparent capacitor 130. The photodetector 102 is located in the substrate 100. The transparent capacitor 130 is located directly above the photodetector 102. The transparent capacitor 130 has an upper surface S2 and an upper surface S3. The upper surface S3 is higher than the upper surface S2.

[0063] The image sensor structure 10 may further include a dielectric structure 116 and a dielectric structure 144. The dielectric structure 116 is located between the transparent capacitor 130 and the substrate 100. An opening OP1 may be provided in the dielectric structure 116. The opening OP1 may be located directly above the photodetector 102. The transparent capacitor 130 is located in the opening OP1 and on the top surface S1 of the dielectric structure 116. The dielectric structure 144 is located on the transparent capacitor 130 and the dielectric structure 116.

[0064] The transparent capacitor 130 may include a transparent electrode layer 124a, a transparent dielectric layer 126a, and a transparent electrode layer 128a stacked in sequence on the dielectric structure 116. The transparent electrode layer 124a may conformally cover the opening OP1 and the top surface S1 of the dielectric structure 116. The transparent dielectric layer 126a may conformally cover the transparent electrode layer 124a. The transparent electrode layer 128a may conformally cover the transparent dielectric layer 126a.

[0065] The image sensor structure 10 may further include an interconnect structure 120 and an interconnect structure 138. The interconnect structure 120 is located in the dielectric structure 116. The interconnect structure 120 may be electrically connected to the transparent electrode layer 124a. In some embodiments, the interconnect structure 120 may be connected to a portion of the transparent electrode layer 124a that is directly above the top surface S1 of the dielectric structure 116. The interconnect structure 138 is located in the dielectric structure 144. The interconnect structure 138 may be electrically connected to the transparent electrode layer 128a. In some embodiments, the interconnect structure 138 may be connected to a portion of the transparent electrode layer 128a that is directly above the top surface S1 of the dielectric structure 116.

[0066] The image sensor structure 10 may further include a color filter layer 146 and a microlens 148. The color filter layer 146 is located on the dielectric structure 144. The microlens 148 is located on the color filter layer 146. In addition, the image sensor structure 10 may further include a transistor 104 and a transistor 110. The transistor 104 and the transistor 110 may be located on the substrate 100. Although not shown in the figure, the transparent electrode layer 124a may be electrically connected to the source (not shown) of the transistor 110 through conductive members such as the interconnect structure 120.

[0067] In addition, the details of each component in the image sensor structure 10 (such as materials and formation methods, etc.) have been described in detail in the above embodiments and will not be described herein again.

[0068] Based on the above embodiments, in the image sensor structure 10, the transparent capacitor 130 is located directly above the photodetector 102. The transparent capacitor 130 has an upper surface S2 and an upper surface S3. The upper surface S3 is higher than the upper surface S2. Therefore, the transparent capacitor 130 can have a larger capacitance value, thereby reducing the thermal noise. In addition, since the transparent capacitor 130 located directly above the photodetector 102 can function as a light pipe, the obliquely incident light can be reflected to the photodetector 102, thereby improving the quantum efficiency (QE). Since the image sensor structure 10 can reduce the thermal noise and improve the quantum efficiency, the image sensor structure 10 can have better electrical performance.

[0069] In summary, in the image sensor structure of the above embodiments, the transparent capacitor is located directly above the photodetector. The transparent capacitor has a first upper surface and a second upper surface. The second upper surface is higher than the first upper surface. Therefore, the transparent capacitor can have a larger capacitance value, thereby reducing the thermal noise. In addition, since the transparent capacitor located directly above the photodetector can function as a light pipe, the obliquely incident light can be reflected to the photodetector, thereby improving the quantum efficiency. Since the image sensor structure of the above embodiments can reduce the thermal noise and improve the quantum efficiency, the image sensor structure of the above embodiments can have better electrical performance.

[0070] Although the present invention is disclosed in combination with the above embodiments, it is not intended to limit the present invention. Any person of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. An image sensor structure, comprising: a substrate; a photodetector located in the substrate; and a transparent capacitor located directly above the photodetector, wherein the transparent capacitor has a first upper surface and a second upper surface, and the second upper surface is higher than the first upper surface.

2. The image sensor structure according to claim 1, wherein the photodetector comprises a photodiode.

3. The image sensor structure according to claim 1, further comprising: a first dielectric structure located between the transparent capacitor and the substrate, wherein there is an opening in the first dielectric structure, the opening is located directly above the photodetector, and the transparent capacitor is located in the opening and on the top surface of the first dielectric structure; and a second dielectric structure located on the transparent capacitor and the first dielectric structure.

4. The image sensor structure according to claim 3, wherein the transparent capacitor comprises a first transparent electrode layer, a transparent dielectric layer, and a second transparent electrode layer stacked in sequence on the first dielectric structure.

5. The image sensor structure according to claim 4, wherein the first transparent electrode layer conformally lies in the opening and on the top surface of the first dielectric structure, the transparent dielectric layer conformally lies on the first transparent electrode layer, and the second transparent electrode layer conformally lies on the transparent dielectric layer.

6. The image sensor structure according to claim 4, wherein the light transmittance of the first transparent electrode layer is 80% to 95%, the light transmittance of the transparent dielectric layer is 80% to 95%, and the light transmittance of the second transparent electrode layer is 80% to 95%.

7. The image sensor structure according to claim 4, wherein the light transmittance of the first transparent electrode layer is 85% to 90%, the light transmittance of the transparent dielectric layer is 90% to 95%, and the light transmittance of the second transparent electrode layer is 85% to 90%.

8. The image sensor structure according to claim 4, further comprising: a first interconnection structure located in the first dielectric structure and electrically connected to the first transparent electrode layer; and a second interconnection structure located in the second dielectric structure and electrically connected to the second transparent electrode layer.

9. The image sensor structure according to claim 8, wherein the first interconnection structure is connected to the portion of the first transparent electrode layer directly above the top surface of the first dielectric structure, and the second interconnection structure is connected to the portion of the second transparent electrode layer directly above the top surface of the first dielectric structure.

10. The image sensor structure according to claim 3, further comprising: a color filter layer located on the second dielectric structure; and a microlens located on the color filter layer.

Images