Transparent electrode with light filtering function, manufacturing method thereof and image sensor
By using the conductive stack of alternately arranged metal layers and transparent conductive oxide layers in the image sensor, the problem of thick and expensive traditional infrared light cutoff filters is solved, and a combination of high light penetration and good conductivity is achieved.
Patent Information
- Application Number
- CN202410460895.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-12-28
- Filing Date
- 2024-04-17
- Publication Date
- 2025-07-04
AI Technical Summary
Traditional infrared light cutoff filters are thick and expensive, and are difficult to manufacture, and cannot meet the high light penetration rate and good conductivity at the same time.
The conductive stack of a plurality of metal layers and a transparent conductive oxide layer arranged alternately is adopted, the sheet resistance is less than 35Ω/sq, the average light penetration is greater than 50% in the band 400nm to 700nm, and the protective dielectric layer is covered on the conductive stack.
It realizes infrared light cutoff function, and has high light penetration and good conductivity, reducing manufacturing difficulty and cost.
Smart Images
Figure CN120264889A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a transparent electrode with a light filtering function, an image sensor using the transparent electrode, and a method for fabricating the transparent electrode. Background Art
[0002] An image sensor is a common semiconductor device for converting an optical signal into an electrical signal. Image sensors are generally classified into charge-coupled device (CCD) sensors and complementary metal-oxide semiconductor (CMOS) sensors. A CMOS image sensor includes a photodiode for detecting incident light and converting it into an electrical signal output, and a logic circuit for transmitting or processing the electrical signal.
[0003] Taking a color (RGB) camera module as an example, an image sensor including a silicon substrate, such as a CCD or CMOS image sensor. An infrared cut-off filter for blocking near-infrared light is coated on glass and then assembled with a lens module, and then the lens module is combined with the image sensor. Traditional infrared cut-off filters include a large number of dielectric layer stacks and are relatively thick. In addition, an infrared cut-off filter made entirely of dielectric materials is not only expensive but also has a certain manufacturing difficulty. Summary of the Invention
[0004] An embodiment of the present disclosure provides a transparent electrode with a light filtering function. The transparent electrode includes a substrate and a conductive stack disposed on the substrate. The conductive stack includes a plurality of metal layers and a plurality of transparent conductive oxide layers alternately arranged, wherein the sheet resistance of the conductive stack is less than 35 Ω / sq, and the average light transmittance of the conductive stack in a wavelength band between 400 nm and 700 nm is greater than 50%.
[0005] In some embodiments, the thickness of the conductive stack is less than 1.5 μm, and the number of pairs of metal layers and transparent conductive oxide layers in the conductive stack is between 10 and 30.
[0006] In some embodiments, the conductive stack has a rectangular cross-section.
[0007] In some embodiments, the conductive stack has a trapezoidal cross-section, and the angle between the side wall of the conductive stack and the upper surface of the substrate is less than 40 degrees.
[0008] In some embodiments, the average optical density of the conductive stack in a wavelength band between 900 nm and 1100 nm is greater than 2.
[0009] In some embodiments, the material of the metal layer is selected from the group consisting of silver, gold, copper, iron, aluminum, platinum, nickel, and combinations thereof.
[0010] In some embodiments, the material of the transparent conductive oxide layer is selected from the group consisting of In2O3, In2O3-ZnO, AZO, GZO, ITO, IZO, IWO, MZO, ATO, FTO, IGTO, SnO2, TNO, TiN, Cu2O, Ta2O x , GaInO x , InGaZnO, Zn x SnO y , ZnGa x O y , GaInO x , Zn x In y O z , VO x , and MoO x and combinations thereof.
[0011] In some embodiments, the refractive index of the transparent conductive oxide layer is greater than 1.6, and the extinction coefficient of the transparent conductive oxide layer is less than 0.1 in the wavelength range of 400 nm to 700 nm.
[0012] In some embodiments, the transparent electrode further includes a protective dielectric layer covering the upper surface and sidewalls of the conductive stack, wherein the thickness of the protective dielectric layer is greater than 200 nm.
[0013] In some embodiments, the transparent electrode further includes a first dielectric layer disposed on the conductive stack, an additional conductive stack disposed on the first dielectric layer, a second dielectric layer disposed on the additional conductive stack, and metal plugs. The metal plugs penetrate the conductive stack, the first dielectric layer, the additional conductive stack, and the second dielectric layer.
[0014] In some embodiments, the signal-to-noise ratio of the transparent electrode is greater than 600 in the wavelength range of 400 nm to 1000 nm.
[0015] In some embodiments, the response time of the transparent electrode is greater than 10 4 Hz at an applied voltage of 4 volts.
[0016] In some embodiments, the on / off current ratio of the transparent electrode is greater than 10 4 at an applied voltage of 0.1 volts.
[0017] Another embodiment of the present disclosure provides an image sensor, comprising a semiconductor substrate, a readout circuit disposed within the semiconductor substrate, a lower electrode disposed on the surface of the semiconductor substrate, a photoelectric conversion layer disposed on the lower electrode, a transparent electrode disposed on the photoelectric conversion layer, and a contact connecting the transparent electrode to the lower electrode. The transparent electrode comprises a conductive stack disposed on the semiconductor substrate, the conductive stack comprising a plurality of alternating metal layers and a plurality of transparent conductive oxide layers, wherein the sheet resistance of the conductive stack is less than 35 Ω / sq, and the average light transmittance of the conductive stack in the wavelength band between 400 nm and 700 nm is greater than 50%.
[0018] In some embodiments, the photoelectric conversion layer comprises an organic layer, a quantum well layer, or a perovskite layer.
[0019] In some embodiments, the image sensor further comprises a microlens layer disposed on the transparent electrode, a color filter layer disposed between the microlens layer and the transparent electrode, and a spacer layer disposed between the color filter layer and the transparent electrode.
[0020] Another embodiment of the present disclosure provides a method for fabricating a transparent electrode with a light filtering function, the method comprising the following steps: (a) sputter depositing a metal layer on a substrate; (b) sputter depositing a transparent conductive oxide layer on the substrate; repeating steps (a) and (b) to form a conductive laminate on the substrate; and patterning the conductive laminate to form a conductive stack on the substrate. The sheet resistance of the conductive stack is less than 35 Ω / sq, and the average light transmittance of the conductive stack in the wavelength band between 400 nm and 700 nm is greater than 50%.
[0021] In some embodiments, step (a) is performed in an argon environment, and step (b) is performed in an argon / oxygen environment.
[0022] In some embodiments, the process power or working pressure used in step (a) is higher than the process power or working pressure used in step (b).
[0023] In some embodiments, the method further comprises performing a plasma cleaning process on the substrate before performing steps (a) and (b).
[0024] The transparent electrode provided by the present disclosure not only provides the function of infrared light cutoff, but also meets the requirements of high light transmittance and good electrical conductivity. Description of the Drawings
[0025] To make the objectives, features, advantages, and embodiments of the present disclosure more obvious and understandable, the detailed description of the accompanying drawings is as follows:
[0026] Figure 1Schematic cross-sectional view of some embodiments of a transparent electrode having a light filtering function according to the present disclosure.
[0027] Figure 2 Graph of wavelength versus light transmittance of a conductive stack in a transparent electrode according to some embodiments of the present disclosure.
[0028] Figure 3 Graph of wavelength versus light transmittance of a conductive stack in a transparent electrode according to some embodiments of the present disclosure.
[0029] Figure 4 Graph of wavelength versus optical density (OD) of a conductive stack in a transparent electrode according to some embodiments of the present disclosure.
[0030] Figure 5 Schematic cross-sectional view of some embodiments of a transparent electrode having a light filtering function according to the present disclosure.
[0031] Figure 6 Schematic cross-sectional view of some embodiments of a transparent electrode having a light filtering function according to the present disclosure.
[0032] Figure 7 Schematic cross-sectional view of some embodiments of a transparent electrode having a light filtering function according to the present disclosure.
[0033] Figure 8 Schematic cross-sectional view of some embodiments of an image sensor according to the present disclosure.
[0034] Figure 9 Schematic cross-sectional view of some embodiments of an image sensor according to the present disclosure.
[0035] Figure 10 Flowchart of some embodiments of a method for fabricating a transparent electrode having a light filtering function according to the present disclosure.
[0036] Wherein, the reference numerals are explained as follows:
[0037] 100: Transparent electrode
[0038] 110: Substrate
[0039] 112: Upper surface
[0040] 120: Conductive stack
[0041] 120a: First conductive stack
[0042] 120b: Second conductive stack
[0043] 120c: Third conductive stack
[0044] 122: Metal layer
[0045] 124: Transparent conductive oxide layer
[0046] 126: Sidewall
[0047] 128: Upper surface
[0048] 130: Protective dielectric layer
[0049] 140a: First dielectric layer
[0050] 140b: Second dielectric layer
[0051] 140c: Third dielectric layer
[0052] 150: Metal plug
[0053] 200: CMOS image sensing element
[0054] 300: Image sensor
[0055] 310: Semiconductor substrate
[0056] 320: Readout circuit
[0057] 330: Lower electrode
[0058] 340: Photoelectric conversion layer
[0059] 350: Contact
[0060] 360: Microlens layer
[0061] 370: Color filter layer
[0062] 372: Color filter
[0063] 380: Spacer layer
[0064] S10, S12, S14, S16, S18: Steps
[0065] θ: Angle between planes Detailed implementation manners
[0066] The spirit of the present disclosure will be clearly described below with reference to the drawings and detailed descriptions. After understanding the preferred embodiments of the present disclosure, those of ordinary skill in the art can make changes and modifications based on the techniques taught by the present disclosure without departing from the spirit and scope of the present disclosure.
[0067] Refer to Figure 1, which is a cross-sectional schematic diagram of some embodiments of the transparent electrode with filtering function according to the present disclosure. The transparent electrode 100 with filtering function (hereinafter referred to as transparent electrode 100) includes a substrate 110 and a conductive stack 120 disposed on the substrate 110. The substrate 110 is a semiconductor substrate. The conductive stack 120 includes two different conductive materials. For example, the conductive stack 120 includes a plurality of metal layers 122 and a plurality of transparent conductive oxide layers 124 that are alternately disposed. The sheet resistance of the conductive stack 120 is less than 35Ω / sq, so that the conductive stack 120 can be used as an electrode. The average light transmittance of the conductive stack 120 in the wavelength band between 400nm and 700nm is greater than 50%, so that the transparent electrode 100 can be used as a filter.
[0068] Unlike conventional infrared light cutoff filters that have a large number of dielectric layer stacks and have a relatively thick thickness, such as 38 pairs of dielectric material layers having a thickness of about 4.4 μm, the thickness of the transparent electrode 100 and the number of layer pairs in the present disclosure are greatly reduced. For example, the thickness of the conductive stack 120 is less than 1.5 μm, and the number of pairs of the metal layer 122 and the transparent conductive oxide layer 124 in the conductive stack 120 is between 10 and 30. In some embodiments, the conductive stack 120 has a rectangular cross-section on the substrate 110.
[0069] In some embodiments, the material of the metal layer 122 in the conductive stack 120 is selected from the group consisting of silver, gold, copper, iron, aluminum, platinum, nickel, and combinations thereof. In some embodiments, the material of the transparent conductive oxide layer 124 in the conductive stack 120 is selected from the group consisting of In2O3, In2O3-ZnO, AZO, GZO, ITO, IZO, IWO, MZO, ATO, FTO, IGTO, SnO2, TNO, TiN, Cu2O, Ta2O x 、GaInO x 、InGaZnO、Zn x SnO y , ZnGa x O y 、GaInO x 、Zn x In y O z , VO x , and MoO x In some embodiments, the refractive index of the transparent conductive oxide layer 124 is greater than 1.6, and the extinction coefficient of the transparent conductive oxide layer 124 is less than 0.1 within a wavelength range of 400 nm to 700 nm.
[0070] In some embodiments, the transparent electrode 100 includes a conductive stack 120 having a low sheet resistance. For example, the sheet resistance of the conductive stack 120 is less than 35 Ω / sq, and the transparent electrode 100 has good operating characteristics. For example, in some embodiments, the signal-to-noise ratio (S / N ratio) of the transparent electrode 100 is greater than 600 in the wavelength band between 400 nm and 1000 nm. For example, in some embodiments, the response time of the transparent electrode 100 is greater than 10 4 Hz when a voltage of 4 volts is applied. For example, in some embodiments, the ON / OFF ratio of the transparent electrode 100 is greater than 10 4 when a voltage of 0.1 volts is applied.
[0071] Referring to Figure 2 , which is a graph of wavelength versus light transmittance of the conductive stack in a transparent electrode according to some embodiments of the present disclosure. According to some embodiments, in the visible light band, such as in the wavelength band between 400 nm and 700 nm, the average light transmittance of the conductive stack 120 is greater than 50%, and in the band greater than 750, the light transmittance of the conductive stack 120 approaches zero.
[0072] Referring to Figure 3 , which is a graph of wavelength versus light transmittance of the conductive stack in a transparent electrode according to some embodiments of the present disclosure. According to some embodiments, the average light transmittance of the conductive stack 120 in the wavelength bands of red light (R), green light (G), and blue light (B) is greater than 50%, and in the band greater than 750, the light transmittance of the conductive stack 120 approaches zero.
[0073] Referring to Figure 4 , which is a graph of wavelength versus optical density (OD) of the conductive stack in a transparent electrode according to some embodiments of the present disclosure. According to some embodiments, the average optical density of the conductive stack 120 in the wavelength band between 900 nm and 1100 nm is greater than 2.
[0074] Referring to Figure 5 , which is a cross-sectional schematic diagram of some embodiments of a transparent electrode having a light filtering function according to the present disclosure. In some embodiments, the conductive stack 120 disposed on the substrate 110 can be patterned such that the conductive stack 120 has a trapezoidal cross-section. In some embodiments, the conductive stack 120 disposed on the substrate 110 can be patterned by an etching process, and the angle θ between the sidewall 126 of the conductive stack 120 and the upper surface 112 of the substrate 110 is less than 40 degrees.
[0075] Referring to Figure 6, which is a cross-sectional schematic diagram of some embodiments of a transparent electrode with a light filtering function according to the present disclosure. In some embodiments, the transparent electrode 100 further includes a protective dielectric layer 130 that covers the sidewalls 126 and the upper surface 128 of the conductive stack 120. In some embodiments, the protective dielectric layer 130 further covers the upper surface 112 of the substrate 110 surrounding the conductive stack 120. In this way, the conductive stack 120 is sealed by the protective dielectric layer 130 and the substrate 110.
[0076] In some embodiments, the material of the protective dielectric layer 130 can be an oxide, such as silicon dioxide, and the thickness of the protective dielectric layer 130 is greater than 200 nm. The protective dielectric layer 130 can protect the conductive stack 120 from damage by moisture and oxygen.
[0077] In some embodiments, the protective dielectric layer 130 can be conformally deposited on the conductive stack 120 and the substrate 110. For example, as Figure 6 shown, if the conductive stack 120 has a trapezoidal profile, the protective dielectric layer 130 deposited on the conductive stack 120 also has a trapezoidal profile. In some other embodiments, as Figure 1 shown, if the conductive stack 120 has a rectangular profile, the protective dielectric layer 130 deposited on the conductive stack 120 also has a rectangular profile.
[0078] Referring to Figure 7 , which is a cross-sectional schematic diagram of some embodiments of a transparent electrode with a light filtering function according to the present disclosure. In some embodiments, the transparent electrode 100 includes a plurality of conductive stacks 120, and the transparent electrode 100 is connected to a semiconductor element, such as a CMOS image sensing element 200. For example, the transparent electrode 100 includes a first conductive stack 120a, a second conductive stack 120b, and a third conductive stack 120c. The transparent electrode 100 further includes a first dielectric layer 140a disposed on the first conductive stack 120a, a second dielectric layer 140b disposed on the second conductive stack 120b, and a third dielectric layer 140c disposed on the third conductive stack 120c. The transparent electrode 100 further includes a plurality of metal plugs 150. The metal plugs 150 pass through the third dielectric layer 140c, the third conductive stack 120c, the second dielectric layer 140b, the second conductive stack 120b, the first dielectric layer 140a, and the first conductive stack 120a and are coupled to the CMOS image sensing element 200. In some embodiments, the material of the metal plugs 150 can be tungsten or AlCu. In some embodiments, the metal plugs 150 are respectively coupled to a positive voltage or a negative voltage.
[0079] Referring to Figure 8, which is a cross-sectional schematic diagram of some embodiments of an image sensor according to the present disclosure. The image sensor 300 includes a semiconductor substrate 310, a read circuit 320 disposed in the semiconductor substrate 310, a plurality of lower electrodes 330 disposed on the surface of the semiconductor substrate 310 and coupled to the read circuit 320, a photoelectric conversion layer 340 disposed on the lower electrodes 330, a transparent electrode 100 disposed on the photoelectric conversion layer 340, and a contact 350 that couples the transparent electrode 100 to the corresponding lower electrode 330.
[0080] In some embodiments, the image sensor 300 can be a monochromatic image sensor. In some embodiments, the photoelectric conversion layer 340 includes an organic layer, a quantum well layer, or a perovskite layer. The photoelectric conversion layer 340 continuously extends on the lower electrodes 330. In some embodiments, the image sensor 300 includes a microlens layer 360 disposed on the transparent electrode 100.
[0081] Refer to Figure 9 , which is a cross-sectional schematic diagram of some embodiments of an image sensor according to the present disclosure. In some embodiments, the image sensor 300 can be a color image sensor, and the image sensor 300 further includes a color filter layer 370 disposed between the microlens layer 360 and the transparent electrode 100. The color filter layer 370 includes a plurality of color filters 372, such as color filters corresponding to red (R), green (G), blue (B), yellow (Y), transparent, magenta (M), and cyan (C). The image sensor 300 further includes a spacer layer 380 disposed between the color filter layer 370 and the transparent electrode 100. The spacer layer 380 can be a dielectric material or a transparent photoresist, which is used to protect the underlying structure from being damaged during the fabrication of the color filter layer 370. In some embodiments, the refractive index and thickness of the spacer layer 380 can be controlled to adjust the focal length of incident light on the photoelectric conversion layer 340.
[0082] Refer to Figure 10 , which is a flowchart of some embodiments of a method for fabricating a transparent electrode with a filtering function according to the present disclosure. The method includes step S12 of forming a conductive stack on a substrate. Step S12 includes a loop of repeatedly executing step S14 and step S16, where step S14 is sputter-depositing a metal layer on the substrate, and step S16 is sputter-depositing a transparent conductive oxide layer on the substrate.
[0083] In some embodiments, the material of the metal layer is selected from the group consisting of silver, gold, copper, iron, aluminum, platinum, nickel, and combinations thereof. In some embodiments, the material of the transparent conductive oxide layer is selected from the group consisting of In2O3, In2O3-ZnO, AZO, GZO, ITO, IZO, IWO, MZO, ATO, FTO, IGTO, SnO2, TNO, TiN, Cu2O, Ta2O x 、GaInO x 、InGaZnO、Zn x SnO y 、ZnGa x O y 、GaInO x 、Zn x In y O z 、VO x 、and MoO x and combinations thereof. In some embodiments, the number of times steps S14 and S16 are repeated is between 10 and 30.
[0084] After the conductive stack is formed on the substrate, the method proceeds to step S18. In step S18, the conductive stack is patterned to form a conductive stack on the substrate, whereby a transparent electrode can be obtained. The sheet resistance of the conductive stack is less than 35 Ω / sq, and the average light transmittance of the conductive stack in the wavelength band between 400 nm and 700 nm is greater than 50%.
[0085] In some embodiments, in order to enhance the adhesion of the conductive stack to the substrate, step S10 can be performed before steps S14 and S16. In step S10, a plasma cleaning process is performed on the substrate. For example, step S10 includes cleaning the substrate with a low-power argon plasma in the sputtering chamber for about 15 minutes.
[0086] In some embodiments, step S14 of sputter-depositing the metal layer and step S16 of sputter-depositing the transparent conductive oxide layer can be continuously performed in the same chamber, such that the metal layer and the transparent conductive oxide layer are continuously deposited on the substrate.
[0087] In some embodiments, the initial pressure of the sputtering chamber is 10 -7 to 10 -8 Torr. The distance from the target to the substrate is maintained at about 30 cm. In some embodiments, step S14 of sputter-depositing the metal layer and step S16 of sputter-depositing the transparent conductive oxide layer can be performed at room temperature.
[0088] In some embodiments, step S14 of sputter-depositing the metal layer is performed in a pure argon environment, where the flow rate of argon is about 30 sccm. Step S16 of sputter-depositing the transparent conductive oxide layer is performed in an argon / oxygen environment, and the flow rate ratio is about 18:2.
[0089] In some embodiments, the process power used in step S14 of sputter-depositing the metal layer is higher than the process power used in step S16 of sputter-depositing the transparent conductive oxide layer. For example, when performing step S14 of sputter-depositing the metal layer with a silver target, the process power used is 800 W of direct current, and the working pressure is 3 mTorr, while when performing step S16 of sputter-depositing the transparent conductive oxide layer with an IZO target, the process power used is 350 W of direct current, and the working pressure is 3 mTorr.
[0090] In some embodiments, the working pressure used in step S14 of sputter-depositing the metal layer is higher than the working pressure used in step S16 of sputter-depositing the transparent conductive oxide layer. For example, when performing step S14 of sputter-depositing the metal layer with a silver target, the process power used is 100 W of direct current, and the working pressure is 2 mTorr, while when performing step S16 of sputter-depositing the transparent conductive oxide layer with an IZO target, the process power used is 100 W of direct current, and the working pressure is 1.4 mTorr.
[0091] The transparent electrode provided by the present disclosure not only provides the function of infrared light cutoff, but also meets the requirements of high light transmittance and good electrical conductivity at the same time.
[0092] Although the present disclosure has been disclosed above by way of examples, it is not intended to limit the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be defined by the appended claims.
Claims
1. A transparent electrode with a light filtering function, characterized in that, The transparent electrode comprises: a substrate; and a conductive stack disposed on the substrate, the conductive stack comprising a plurality of metal layers and a plurality of transparent conductive oxide layers alternately arranged, wherein the sheet resistance of the conductive stack is less than 35 Ω / sq, and the average light transmittance of the conductive stack in the wavelength band between 400 nm and 700 nm is greater than 50%.
2. The transparent electrode according to claim 1, wherein The thickness of the conductive stack is less than 1.5 μm, and the number of pairs of the plurality of metal layers and the plurality of transparent conductive oxide layers in the conductive stack is between 10 and 30.
3. The transparent electrode according to claim 1, wherein The conductive stack has a rectangular cross-section, or the conductive stack has a trapezoidal cross-section, and the included angle between the side wall of the conductive stack and the upper surface of the substrate is less than 40 degrees.
4. The transparent electrode according to claim 1, characterized in that, The average optical density of the conductive stack in the wavelength band between 900 nm and 1100 nm is greater than 2.
5. The transparent electrode according to claim 1, wherein The material of the plurality of metal layers is selected from the group consisting of silver, gold, copper, iron, aluminum, platinum, nickel, and combinations thereof.
6. The transparent electrode according to claim 1, characterized in that, The materials of the plurality of transparent conductive oxide layers are selected from the group consisting of In2O3, In2O3-ZnO, AZO, GZO, ITO, IZO, IWO, MZO, ATO, FTO, IGTO, SnO2, TNO, TiN, Cu2O, Ta2O x , GaInO x , InGaZnO, Zn x SnO y , ZnGa x O y , GaInO x , Zn x In y O z , VO x , and MoO x . The refractive index of the plurality of transparent conductive oxide layers is greater than 1.6, and the extinction coefficient of the plurality of transparent conductive oxide layers is less than 0.1 in the wavelength band between 400 nm and 700 nm.
7. The transparent electrode according to claim 1, wherein Further comprising a protective dielectric layer covering the upper surface and the side walls of the conductive stack, wherein the thickness of the protective dielectric layer is greater than 200 nm.
8. The transparent electrode according to claim 1, characterized in that, Further comprising: a first dielectric layer disposed on the conductive stack; an additional conductive stack disposed on the first dielectric layer; a second dielectric layer disposed on the additional conductive stack; and a metal plug passing through the conductive stack, the first dielectric layer, the additional conductive stack, and the second dielectric layer.
9. The transparent electrode according to claim 1, wherein The signal-to-noise ratio of the transparent electrode is greater than 600 in the wavelength band between 400 nm and 1000 nm.
10. The transparent electrode according to claim 1, characterized in that, The response time of the transparent electrode is greater than 10 4 Hz. When the applied voltage is 4 volts, the on / off current ratio of the transparent electrode is greater than 10 4 , when the applied voltage is 0.1 volts.
11. An image sensor, characterized in that, Comprising: a semiconductor substrate; a read circuit disposed in the semiconductor substrate; a lower electrode disposed on a surface of the semiconductor substrate; a photoelectric conversion layer disposed on the lower electrode; a transparent electrode disposed on the photoelectric conversion layer, the transparent electrode comprising: a conductive stack disposed on the semiconductor substrate, the conductive stack comprising a plurality of metal layers and a plurality of transparent conductive oxide layers alternately arranged, wherein the sheet resistance of the conductive stack is less than 35 Ω / sq, and the average light transmittance of the conductive stack in the wavelength band between 400 nm and 700 nm is greater than 50%; and a contact connecting the transparent electrode to the lower electrode.
12. The image sensor according to claim 11, wherein The photoelectric conversion layer comprises an organic layer, a quantum well layer, or a perovskite layer, and the image sensor further comprises: a microlens layer disposed on the transparent electrode; a color filter layer disposed between the microlens layer and the transparent electrode; and a spacer layer disposed between the color filter layer and the transparent electrode.
13. A method for fabricating a transparent electrode with a light filtering function, characterized in that, The method comprises the following steps: (a) Sputtering and depositing a metal layer on a substrate; (b) Sputtering and depositing a transparent conductive oxide layer on the substrate; Repeatedly performing step (a) and step (b) to form a conductive laminate on the substrate; and Patterning the conductive laminate to form a conductive stack on the substrate, wherein the sheet resistance of the conductive stack is less than 35 Ω / sq, and the average light transmittance of the conductive stack in the wavelength band between 400 nm and 700 nm is greater than 50%.
14. The method according to claim 13, characterized in that, Step (a) is performed in an argon environment, and step (b) is performed in an argon / oxygen environment, where the process power or working pressure used in step (a) is higher than the process power or working pressure used in step (b). The method further includes: Before performing step (a) and step (b), a plasma cleaning process is performed on the substrate.