A method for fabricating a photoelectric conversion array device

Abstract

The application discloses a manufacturing method of a photoelectric conversion array device. A photoelectric conversion array is prepared on a substrate, and an upward-opening groove is formed at each pixel position; photoelectric conversion film material is deposited in all the grooves through a spin coating or laminating process, so that a main part of the photoelectric conversion film material is embedded in the opening groove, and a residual film layer is formed on the outer surface of the groove; a back etching process is used to remove the residual film layer on the outer surface of the groove, and pixelization of the photoelectric conversion film layer is completed; a second carrier transport layer and a top electrode are prepared on the pixelized photoelectric conversion film layer. The application combines the groove pixel structure design with the laminating / spin coating process, and innovatively realizes low-damage and high-precision pixelization of the film material. The pixelized film material has the technical advantage of small crosstalk, especially in the field of small pixel devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor photoelectric detection and light-emitting device manufacturing, and relates to a method for manufacturing a photoelectric conversion array device, specifically a manufacturing process for forming a pixelated photoelectric conversion array based on an open groove structure and a back-etching process on a formed photoelectric thin film. Background Art

[0002] In imaging sensor arrays based on quantum dot films, organic photodiode (OPD) films, or organic light-emitting diode (OLED) film technology, crosstalk between pixels is a core issue affecting imaging (or light emission) quality. Crosstalk manifests itself as the mutual interference of optical or electrical signals between adjacent pixels, resulting in image blur, color distortion, or increased noise. There are two main causes of crosstalk between pixels:

[0003] 1. Carrier diffusion: In quantum dots or OPD films, photogenerated carriers may diffuse laterally to adjacent pixel areas, especially when the film thickness is large or there are many material defects.

[0004] 2. Light scattering and reflection: The incident light is scattered on the film surface or pixel edge, and some photons are absorbed by adjacent pixels, resulting in signal interference between pixels.

[0005] How to reduce crosstalk between pixels is a common technical challenge faced by small-size photoelectric conversion array (imaging pixel or luminous pixel) array devices.

[0006] Photoelectric thin film materials are typically deposited on a flat imaging array surface. To reduce crosstalk between pixels in a photosensitive or luminescent array, the photoelectric thin film material deposited on the surface can be pixelated. This involves segmenting the photoelectric thin film material (pixelation). After segmentation, dielectric materials and other materials are typically used to fill the segmented spaces to achieve better isolation and protection for the segmented thin film material. The segmentation (pixelation) of the photoelectric thin film is typically performed using a photolithography-plus-etching method, with both dry and wet etching methods. As pixel size decreases, dry etching, with its superior anisotropic etching properties, has become the primary thin film pixelation etching process.

[0007] The existing photoelectric thin film pixelation process mainly uses the photolithography and etching method commonly used in integrated circuit manufacturing technology. However, this technical route inevitably introduces damage to the photoelectric thin film material, including:

[0008] 1) Chemical damage: Photoresist solvents, developers, or etching gases (such as oxygen plasma) can corrode or modify organic thin films (such as OPD) or quantum dot materials. For example, the organic semiconductor layer in OPD is easily damaged by the alkaline developer in the photoresist, resulting in a decrease in carrier mobility.

[0009] 2) Thermal damage: High-temperature baking during the photolithography process (such as the hard bake step) may cause phase changes or decomposition of heat-sensitive materials (such as certain quantum dots or polymer films), affecting the optoelectronic performance.

[0010] 3) Degradation of optical performance: Photoresist residue or incomplete cleaning after etching will introduce interface states, reducing light absorption efficiency or luminescence efficiency.

[0011] 4) Vertical etching damage layer path: Etching of photoelectric thin films usually produces a certain damage layer. The traditional pixelation method uses vertical through-etching to completely divide the photoelectric film, which will form a damage layer channel connecting the upper and lower electrodes along the vertical direction on the surface of the photoelectric film exposed after etching, thereby deteriorating the dark current and other characteristics of the photoelectric device.

[0012] In summary, the existing process is caught in the trade-off dilemma of "crosstalk suppression-material damage". Therefore, there is an urgent need to develop a non-photolithography, low-thermal-budget, non-through-segmentation pixelation process that can achieve physical isolation while retaining the intrinsic properties of the optoelectronic film, eliminating longitudinal damage channels, and being compatible with micron-level pixel processing precision. Summary of the Invention

[0013] The purpose of the present invention is at least to overcome the shortcomings of the above-mentioned existing thin-film pixelation technology and to provide a method for manufacturing a photoelectric conversion array device, which utilizes an upper-open groove structure for thin-film pixelation. By combining the grooved pixel structure design with a spin coating (or lamination) process and a back-etching process, the low-damage and high-precision pixelation of the thin-film material is innovatively achieved.

[0014] A method for manufacturing a photoelectric conversion array device, the photoelectric conversion array device comprising, from bottom to top, a photoelectric conversion array, a second carrier transport layer, and a top electrode; the photoelectric conversion array comprising, from bottom to top, a dielectric layer, a metal bottom electrode, a first carrier transport layer, a photoelectric sensing film, and an inter-pixel isolation dielectric; a plurality of metal through-holes are provided in the dielectric layer, the lower end of each metal through-hole being connected to a drive circuit; each pixel position of the photoelectric conversion array device corresponds to at least one metal through-hole;

[0015] The first carrier transport layer and the second carrier transport layer are different carrier transport layers, which are electron transport layers or hole transport layers.

[0016] The method comprises:

[0017] A photoelectric conversion array is prepared on a substrate, and a groove with an upward opening is formed at each pixel position;

[0018] Depositing a photoelectric conversion thin film material in all the grooves by spin coating or lamination process, so that the main part of the photoelectric conversion thin film material is embedded in the open grooves and a residual thin film layer is formed on the outer surface of the grooves;

[0019] The residual thin film layer on the outer surface of the groove is removed by the etching back process to complete the pixelation of the photoelectric conversion thin film layer;

[0020] A second carrier transport layer, a top electrode and other electrical connection structures are prepared on the pixelated photoelectric conversion thin film layer.

[0021] Preferably, the depth of the groove matches the thickness of the photoelectric conversion thin film layer. More preferably, the height of the groove ranges from 200 nm to 600 nm.

[0022] Preferably, the cross-sectional width of the groove is 0.05-50 μm.

[0023] Preferably, the sidewall of the groove is sloped or vertical.

[0024] Preferably, the sidewall inclination angle of the groove is 40°~130°.

[0025] Preferably, the photoelectric conversion thin film material includes at least one of an organic photodiode material, an organic light emitting diode material or a quantum dot material, or a combination of several of them.

[0026] Preferably, the etching back process adopts a dry etching process.

[0027] Preferably, the lamination process is mechanical pressure, thermal pressure or a bonding process based on auxiliary adhesives.

[0028] Preferably, the photoelectric conversion array device is a photosensitive imaging array device or a light-emitting array device.

[0029] Compared to existing technologies, this invention effectively prevents chemical damage to the photovoltaic thin film by photoresist and etching solutions, preserving the intrinsic photovoltaic properties of the thin film material. The back-etching process only removes a portion of the top layer of the photovoltaic thin film material, eliminating the creation of longitudinal damaged layer channels and overcoming the through-cut problem of common pixelation processes. Furthermore, since photolithography of the photovoltaic thin film is not required, the thermal load on the film during the entire process is minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a flow chart of a method for manufacturing a photoelectric conversion array device provided in this embodiment.

[0032] Figure 2 for Figure 1 Schematic diagram of the device structure in step S1 of the preparation process.

[0033] Figure 3 for Figure 1 Schematic diagram of the device structure in step S2 of the preparation process.

[0034] Figure 4 for Figure 1 Schematic diagram of the device structure in the preparation process of step S3.

[0035] Figure 5 for Figure 1 Schematic diagram of the device structure in the preparation process of step S4.

[0036] Figure 6 for Figure 1 Schematic diagram of the device structure of step S5 preparation process.

[0037] Figure 7 for Figure 1 Schematic diagram of the device structure of the preparation process in step S6.

[0038] Figure 8 for Figure 1 Schematic diagram of the device structure of the preparation process in step S7.

[0039] Figure 9 for Figure 1 Schematic diagram of the device structure of the preparation process in step S8.

[0040] Markings in the figure: 301, metal through hole; 302, dielectric layer; 303, metal bottom electrode; 304, first carrier transport layer; 305, inter-pixel isolation medium; 306, groove; 307, photoelectric conversion thin film layer; 308, second carrier transport layer; 309, top electrode. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0042] In order to solve the problem that photoelectric film materials (such as Quantum dots, OPD, OLED) applied in photoelectric detection or light-emitting array are difficult to be pixelated, the application provides a manufacturing method of photoelectric conversion array device, in particular to a manufacturing method of photoelectric conversion array device based on photoelectric film sensitive material and for photoelectric imaging application.

[0043] Firstly, the application forms upwardly open grooves with a height close to the thickness of photoelectric conversion film material at the pixel positions in the photoelectric conversion array, and after the photoelectric sensing film is deposited on the array by spin coating or laminating, the main part of the film is embedded in the upwardly open grooves, and only a small part exists outside the grooves, that is, the photoelectric film is deposited or transferred to the grooves, and the spin coating or laminated film is partially pixelated by using the groove topography. Then, the film pixelation is completed by removing the residual film outside the grooves by etching back.

[0044] Specifically, referring to the accompanying drawings, Figure 1 The method comprises the following steps:

[0045] Step S1, referring to Figure 2 A metal via hole 301 is made in the dielectric layer 302 corresponding to each pixel on the readout circuit (or driving circuit) by using a metal damascene process.

[0046] Step S2, referring to Figure 3 A metal bottom electrode 303 and a first carrier transport layer 304 are deposited on the metal via hole 301 in sequence.

[0047] Step S3, referring to Figure 4 The metal bottom electrode 303 layer and the first carrier transport layer 304 material are etched by using a photolithography and etching method (pixelation).

[0048] Step S4, referring to Figure 5 A pixel spacing isolation medium 305 is deposited, and a planarization process is used to reduce the height difference of the photoelectric conversion array surface topography to form a photoelectric conversion array.

[0049] Step S5, referring to Figure 6 An upwardly open groove 306 is formed above each pixel of the photoelectric conversion array by using a photolithography and etching method.

[0050] As an example, the cross-sectional shape of the groove 306 is circular, square, triangular, other polygonal or irregular shape. For example, the cross-sectional width of the groove is 0.05-50 μm, and the height of the groove ranges from 200 nm to 600 nm.

[0051] For example, sidewall angles range from 40° to 130°. Sloped shapes facilitate thin-film filling, while vertical shapes increase integration density. The trench morphology is formed in one pass through the dielectric layer, avoiding the lateral undercutting issues associated with wet etching.

[0052] Step S6, see Figure 7 , a photoelectric thin film material (one layer or multiple layers) is deposited in all the grooves 306 by spin coating or lamination, so that the main part of the photoelectric conversion thin film material is embedded in the open grooves 306 and a residual thin film layer is formed on the outer surface of the grooves 306.

[0053] As an example, the depth of the groove is 50% to 200% of the thickness of the photoelectric conversion thin film material on the flat substrate. Due to the continuity of the thin film during the spin coating and lamination process, part of the thin film layer may remain outside the groove.

[0054] As an example, the spin coating process conditions may be a rotation speed of 2000 rpm to 5000 rpm, a baking temperature after spin coating of 60° C. to 160° C., and a baking time range of 10 minutes to 120 minutes.

[0055] As an example, the photoelectric conversion thin film material includes at least one of an organic photodiode (OPD) material, an organic light emitting diode (OLED) material, or a quantum dot material, or a combination of several of them.

[0056] As an example, the lamination process includes transferring the prefabricated photovoltaic thin film to the surface of the array of opening grooves 306 by mechanical or thermal pressure or auxiliary adhesive.

[0057] This invention directly embeds the trenches through a spin-coating / lamination process, eliminating the photoresist coating and development steps, and preventing contact between photoresist solvents (such as PGMEA) and alkaline developers (such as TMAH) and the organic semiconductor active layer. The trenches provide physical isolation for the photoelectric conversion thin film material, eliminating the need to rely on the material's inherent etch resistance.

[0058] The present invention eliminates the hard baking step in the photolithography process, and the lamination process adopted can be completed at room temperature to a lower temperature, controlling the thermal budget below the phase transition temperature of heat-sensitive materials (such as perovskite quantum dots and polymer OLEDs).

[0059] Step S7, see Figure 8 The residual thin film layer remaining on the outer surface of the groove 306 is etched back to complete the pixelation of the photoelectric thin film, forming a photoelectric conversion thin film layer 307 located in the groove 306.

[0060] As an example, the etch-back process adopts a dry etching process, such as reactive ion etching (RIE) or ion beam etching (IBE).

[0061] The trench depth of the present invention matches the thickness of the photoelectric conversion thin film layer 307. The back etching only removes the residual layer outside the trench, leaving the film intact inside the trench. The film sidewalls are always wrapped by the inter-pixel isolation dielectric 305, preventing the formation of plasma damage paths through the top and bottom electrodes.

[0062] Step S8, see Figure 9 , a second carrier transport layer 308 and a transparent common top electrode 309 (such as ITO) are sequentially deposited on the device to complete the preparation of the photoelectric conversion array device.

[0063] The first carrier transport layer 304 and the second carrier transport layer 308 are different carrier transport layers, namely, electron transport layers or hole transport layers. If the first carrier transport layer 304 is an electron transport layer, the second carrier transport layer 308 is a hole transport layer. If the first carrier transport layer 304 is a hole transport layer, the second carrier transport layer 308 is an electron transport layer.

[0064] In summary, the present invention is primarily targeted at applications in photosensitive imaging array devices, and can also be applied to light-emitting array devices. This involves grooved imaging (or light-emitting) pixel arrays containing pixel bottom electrodes, spin-coating or laminating a photoelectric thin film onto the grooved array, and then removing the remaining thin film outside the grooves by back-etching. This completes the electrical connections of other functional layer structures and top electrodes of the imaging (or light-emitting) pixels. The present invention overcomes the inherent defects of traditional photolithography and etching processes through the core technical approach of "groove morphology constraint + non-through back-etching." The present invention innovatively achieves low-damage, high-precision pixelation of thin film materials by combining a grooved pixel structure design with a lamination / spin-coating process. The pixelated thin film material has the technical advantage of low crosstalk, especially in the field of small pixel devices.

[0065] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for manufacturing a photoelectric conversion array device, wherein the photoelectric conversion array device is a photosensitive imaging array device or a light-emitting array device, characterized in that: The photoelectric conversion array device includes, from bottom to top, a photoelectric conversion array, a second carrier transport layer, and a top electrode; the photoelectric conversion array includes, from bottom to top, a dielectric layer, a metal bottom electrode, a first carrier transport layer, a photoelectric sensing film, and an inter-pixel isolation dielectric; a plurality of metal through-holes are provided in the dielectric layer, and the lower end of each metal through-hole is connected to a driving circuit; each pixel position of the photoelectric conversion array device corresponds to at least one metal through-hole; The first carrier transport layer and the second carrier transport layer are different carrier transport layers, which are electron transport layers or hole transport layers; The method comprises the following process steps: A photoelectric conversion array is prepared on a substrate, and a groove with an upward opening is formed at each pixel position by photolithography and etching; Depositing a photoelectric conversion thin film material in all the grooves by spin coating or lamination process, so that the main part of the photoelectric conversion thin film material is embedded in the open grooves and a residual thin film layer is formed on the outer surface of the grooves; The residual thin film layer on the outer surface of the groove is removed by the etching back process to complete the pixelation of the photoelectric conversion thin film layer; A second carrier transport layer and a top electrode are prepared on the pixelated photoelectric conversion thin film layer.

2. The method according to claim 1, characterized in that The depth of the groove matches the thickness of the photoelectric conversion thin film layer.

3. The method according to claim 2, characterized in that The height of the groove ranges from 200 nm to 600 nm.

4. The method according to claim 1, characterized in that The cross-sectional width of the groove is 0.05-50 μm.

5. The method according to claim 1, characterized in that: The sidewall of the groove is sloped or vertical.

6. The method according to claim 5, characterized in that The sidewall inclination angle of the groove is 40° to 130°.

7. The method according to claim 1, characterized in that: The photoelectric conversion thin film material includes at least one of an organic photodiode material, an organic light emitting diode material or a quantum dot material, or a combination of several of them.

8. The method according to claim 1, characterized in that: The etching back process adopts a dry etching process.

9. The method according to claim 1, characterized in that: The lamination process is mechanical pressure, thermal pressure or a bonding process based on auxiliary adhesives.

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