Manufacturing method of photoelectric conversion array device

Abstract

The invention discloses a manufacturing method of a photoelectric conversion array device. Preparing a photoelectric conversion array on the substrate, and forming a groove with an upward opening at each pixel position; depositing a photoelectric conversion film material in all the grooves through a spin-coating or laminating process, enabling a main body part of the photoelectric conversion film material to be embedded in the open grooves, and forming a residual film layer on the outer surfaces of the grooves; removing the residual thin film layer on the outer surface of the groove by adopting an etchback process, and completing pixelation of the photoelectric conversion thin film layer; and preparing a second carrier transport layer and a top electrode on the pixelated photoelectric conversion film layer. According to the invention, through the combination of the grooved pixel structure design and the lamination / spin-coating process, the low-damage and high-precision pixelatization of the thin film material is innovatively realized. The pixelated thin 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 optoelectronic detection and light-emitting device manufacturing, and relates to a manufacturing method of an optoelectronic conversion array device, specifically a manufacturing process for forming a pixelated optoelectronic conversion array on an optoelectronic thin film formed based on an open trench structure and a re-etching process. Background Art

[0002] In imaging sensor arrays based on quantum dot thin film (Quantum dot) or organic photodiode (OPD) thin film or organic light-emitting diode (OLED) thin film technology, cross-talk between pixels is one of the core problems affecting imaging (or light-emitting) quality. Cross-talk is mainly manifested as the mutual interference of optical signals or electrical signals between adjacent pixels, resulting in image blurring, color distortion, or increased noise. Among them, there are mainly two reasons for cross-talk between pixels: 1. Carrier diffusion: In quantum dots or OPD thin films, photo-generated carriers may laterally diffuse into adjacent pixel regions, especially when the thin film thickness is large or there are many material defects.

[0003] 2. Light scattering and reflection: Incident light is scattered on the thin film surface or pixel edge, and some photons are absorbed by neighboring pixels, resulting in signal interference between pixels.

[0004] How to reduce cross-talk between pixels is a common technical problem faced by small-sized optoelectronic conversion array (imaging pixel or light-emitting pixel) array devices.

[0005] Optoelectronic thin film materials are usually deposited on a flat imaging array plane. In order to reduce cross-talk between pixels in a photosensitive or light-emitting array, the optoelectronic thin film materials deposited on the plane can be pixelated, that is, the optoelectronic thin film materials are segmented (pixelated). After segmentation, materials such as dielectrics are usually used to fill the segmented space to achieve better isolation and protection of the segmented thin film materials. Among them, the segmentation (pixelation) of optoelectronic thin films usually adopts the method of photolithography plus etching, and the etching methods include dry etching and wet etching. As the pixel size gradually shrinks, dry etching with better anisotropic etching characteristics has gradually become the main thin film pixelation etching process.

[0006] The existing optoelectronic thin film pixelation process mainly adopts the method of photolithography plus etching commonly used in integrated circuit manufacturing technology. However, this technical route inevitably introduces damage to optoelectronic thin film materials, specifically including: 1) Chemical damage: Photoresist solvents, developers, or etching gases (such as oxygen plasma) may 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.

[0007] 2) Thermal damage: High-temperature baking during the lithography process (such as the hard baking step) may cause phase changes or decomposition of heat-sensitive materials (such as certain quantum dots or polymer films), affecting the optoelectronic properties.

[0008] 3) Degradation of optical properties: Residual photoresist or incomplete cleaning after etching will introduce interface states, reducing the light absorption efficiency or luminescence efficiency.

[0009] 4) Vertical etched damage layer path: Etching of optoelectronic thin films usually generates a certain damage layer. Traditional pixelation methods completely divide the optoelectronic thin films by using vertical through-etching, thus forming a damage layer channel connecting the upper and lower electrodes longitudinally on the surface of the optoelectronic thin films exposed after etching, deteriorating the characteristics such as dark current of optoelectronic devices.

[0010] In summary, the existing processes are trapped in the trade-off dilemma of "crosstalk suppression - material damage". Therefore, there is an urgent need to develop a non-lithography, low-thermal budget, non-through-division pixelation process, which can retain the intrinsic properties of optoelectronic thin films, eliminate the longitudinal damage channels, and be compatible with the micron-level pixel processing accuracy while achieving physical isolation. Summary of the Invention

[0011] The purpose of the present invention is at least to overcome the above deficiencies of the existing thin film pixelation technology, and provide a manufacturing method of an optoelectronic conversion array device. The thin film pixelation is carried out by using an upper-opening trench structure, and through the combination of trench pixel structure design with spin coating (or lamination) process and re-etching process, the low-damage and high-precision pixelation of thin film materials is innovatively realized.

[0012] A manufacturing method of an optoelectronic conversion array device, the optoelectronic conversion array device sequentially includes an optoelectronic conversion array, a second carrier transport layer, and a top electrode from bottom to top; the optoelectronic conversion array sequentially includes a dielectric layer, a metal bottom electrode, a first carrier transport layer, an optoelectronic induction thin film, and an inter-pixel isolation dielectric from bottom to top. A plurality of metal through-holes are provided in the dielectric layer, and the lower ends of each metal through-hole are connected to a driving circuit; at least one metal through-hole corresponds to each pixel position of the optoelectronic conversion array device; The first carrier transport layer and the second carrier transport layer are different carrier transport layers, which are an electron transport layer or a hole transport layer.

[0013] The method includes: Preparing an optoelectronic conversion array on a substrate, and forming a trench with an upward opening at each pixel position; Depositing an optoelectronic conversion thin film material into all the trenches by spin coating or lamination process, so that the main part of the optoelectronic conversion thin film material is embedded in the opening trenches, and a residual thin film layer is formed on the outer surface of the trenches; The residual thin film layer on the outer surface of the trench is removed by a re-etching process to complete the pixelation of the optoelectronic conversion thin film layer; A second carrier transport layer, a top electrode, and other electrical connection structures are fabricated on the pixelated optoelectronic conversion thin film layer.

[0014] Preferably, the depth of the trench matches the thickness of the optoelectronic conversion thin film layer. More preferably, the height range of the trench is 200 nm to 600 nm.

[0015] Preferably, the cross-sectional width of the trench is 0.05 to 50 μm.

[0016] Preferably, the sidewall of the trench is ramp-shaped or vertical.

[0017] Preferably, the inclination angle of the sidewall of the trench is 40° to 130°.

[0018] Preferably, the optoelectronic conversion thin film material includes at least one or a combination of several of organic optoelectronic diode materials, organic light emitting diode materials, or quantum dot materials.

[0019] Preferably, the re-etching process uses a dry etching process.

[0020] Preferably, the lamination process is a mechanical pressure, a thermal pressure, or an adhesive process based on an auxiliary adhesive.

[0021] Preferably, the optoelectronic conversion array device is a photosensitive imaging array device or a light emitting array device.

[0022] Compared with the prior art, the present invention can effectively avoid the chemical damage of the optoelectronic thin film by photoresist and etching solution, and ensure the intrinsic optoelectronic properties of the thin film material. The re-etching process only removes part of the optoelectronic thin film material on the top layer, and will not generate a longitudinal damage layer channel, overcoming the problem of through-cut segmentation in common pixelation processes. And since lithography is not required for the optoelectronic thin film, the thermal load on the optoelectronic thin film in the entire process flow is also minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0024] Figure 1 It is a flowchart of a method for fabricating an optoelectronic conversion array device provided in this embodiment.

[0025] Figure 2 For Figure 1Schematic diagram of the device structure in the preparation process of step S1.

[0026] Figure 3 is Figure 1 Schematic diagram of the device structure in the preparation process of step S2.

[0027] Figure 4 is Figure 1 Schematic diagram of the device structure in the preparation process of step S3.

[0028] Figure 5 is Figure 1 Schematic diagram of the device structure in the preparation process of step S4.

[0029] Figure 6 is Figure 1 Schematic diagram of the device structure in the preparation process of step S5.

[0030] Figure 7 is Figure 1 Schematic diagram of the device structure in the preparation process of step S6.

[0031] Figure 8 is Figure 1 Schematic diagram of the device structure in the preparation process of step S7.

[0032] Figure 9 is Figure 1 Schematic diagram of the device structure in the preparation process of step S8.

[0033] Markings in the figure: 301, metal via; 302, dielectric layer; 303, metal bottom electrode; 304, first carrier transport layer; 305, pixel isolation dielectric; 306, trench; 307, optoelectronic conversion thin film layer; 308, second carrier transport layer; 309, top electrode. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0035] Aiming at the problem that it is difficult to pixelate optoelectronic thin film materials (such as quantum dots, organic photodiodes OPDs, organic light emitting diodes OLEDs) applied in optoelectronic detection or light emitting arrays, the present invention provides a manufacturing method for an optoelectronic conversion array device, specifically a manufacturing method for an optoelectronic conversion array device based on optoelectronic thin film sensitive materials and for optoelectronic imaging applications.

[0036] The present invention first forms an upward-opening trench with a height close to the thickness of the optoelectronic conversion thin film material at the pixel positions in the optoelectronic conversion array. After depositing the optoelectronic sensing thin film on the array by spin coating or lamination, the main part of the above thin film is embedded in the upward-opening trench, and only a small part exists outside the trench, that is, the optoelectronic thin film is deposited or transferred onto the trench, and partial pixelization of the spin-coated or laminated thin film is achieved by using the trench topography. Then, the remaining thin film outside the trench is removed by a re-etching method to complete the pixelization of the thin film.

[0037] Specifically, referring to the attached Figure 1 , the method of the present invention includes the following steps: Step S1, referring to Figure 2 , using a metal damascene process, one (or more) metal vias 301 are fabricated in the dielectric layer 302 corresponding to each pixel on the readout circuit (or driving circuit).

[0038] Step S2, referring to Figure 3 , a metal bottom electrode 303 and a first carrier transport layer 304 are sequentially deposited on the metal via 301.

[0039] Step S3, referring to Figure 4 , using photolithography and etching methods to etch the metal bottom electrode 303 layer and the first carrier transport layer 304 material (pixelization).

[0040] Step S4, referring to Figure 5 , depositing an inter-pixel isolation dielectric 305, and using a planarization process to reduce the height difference of the surface topography of the optoelectronic conversion array to form the optoelectronic conversion array.

[0041] Step S5, referring to Figure 6 , using photolithography and etching methods to form an upward-opening trench 306 above each pixel of the optoelectronic conversion array.

[0042] As an example, the cross-sectional shape of the trench 306 is circular, square, triangular, other polygon or irregular shape. For example, the cross-sectional width of the trench is 0.05 - 50 μm, and the height range of the trench is 200 nm - 600 nm.

[0043] As an example, the sidewall inclination angle is 40° - 130°. The ramp shape is beneficial for thin film filling, and the vertical shape improves the integration density. The trench topography is formed in one step by dielectric layer etching to avoid the lateral etching problem of wet etching.

[0044] Step S6, referring to Figure 7, the optoelectronic thin film material (one or more layers) is deposited in all the trenches 306 by spin coating or lamination methods, so that the main part of the optoelectronic conversion thin film material is embedded in the open trenches 306, and a residual thin film layer is formed on the outer surface of the trenches 306.

[0045] As an example, the depth of the trench is 50% - 200% of the thickness of the optoelectronic conversion thin film material on the planar substrate. Due to the continuity of the thin film in the spin coating and lamination processes, a partial thin film layer will also remain outside the trench.

[0046] As an example, the spin coating process conditions can be a rotation speed of 2000 rpm - 5000 rpm, a baking temperature after spin coating of 60°C - 160°C, and a baking duration range of 10 minutes - 120 minutes.

[0047] As an example, the optoelectronic conversion thin film material includes at least one or a combination of several of organic photodiode (OPD) materials, organic light emitting diode (OLED) materials, or quantum dot materials.

[0048] As an example, the lamination process includes transferring a prefabricated optoelectronic thin film to the surface of the open trench 306 array by mechanical or thermal pressure or an auxiliary adhesive.

[0049] In the present invention, the trench is directly embedded through the spin coating / lamination process, eliminating the photoresist coating and developing processes, and avoiding the contact between the photoresist solvent (such as PGMEA) and the alkaline developer (such as TMAH) and the organic semiconductor active layer. The trench provides physical isolation for the optoelectronic conversion thin film material, without relying on the etching resistance of the material itself.

[0050] In the present invention, the hard baking step in the lithography process is cancelled, and the lamination process adopted can be completed at room temperature to a relatively low temperature, controlling the thermal budget below the phase transition temperature of thermally sensitive materials (such as perovskite quantum dots, polymer OLEDs).

[0051] Step S7, refer to Figure 8 , the residual thin film layer remaining on the outer surface of the trench 306 is removed by back etching to complete the pixelation of the optoelectronic thin film, forming the optoelectronic conversion thin film layer 307 located in the trench 306.

[0052] As an example, the back etching process adopts a dry etching process, such as reactive ion etching (RIE) or ion beam etching (IBE) process.

[0053] The groove depth of the present invention matches the thickness of the optoelectronic conversion thin film layer 307. The re-etching only removes the residual layer outside the groove, and retains the complete thin film inside the groove. The side walls of the thin film are always wrapped by the inter-pixel isolation medium 305, avoiding the formation of a plasma damage path that penetrates the top / bottom electrodes.

[0054] Step S8, refer to Figure 9 , deposit a second carrier transport layer 308 and a transparent common top electrode 309 (such as ITO) on the device in sequence to complete the preparation of the optoelectronic conversion array device.

[0055] The first carrier transport layer 304 and the second carrier transport layer 308 are different carrier transport layers, which are electron transport layers or hole transport layers. If the first carrier transport layer 304 is an electron transport layer, then the second carrier transport layer 308 is a hole transport layer. If the first carrier transport layer 304 is a hole transport layer, then the second carrier transport layer 308 is an electron transport layer.

[0056] In summary, the present invention is mainly aimed at applications of photosensitive imaging array devices, and can also be applied to light-emitting array devices. By grooving the imaging (or light-emitting) pixel array containing pixel bottom electrodes -> spin-coating or laminating optoelectronic thin films on the groove array -> removing the thin film remaining outside the groove by re-etching -> completing the electrical connections of other functional layers and top electrodes of the imaging (or light-emitting) pixels. The present invention breaks through the inherent defects of traditional photolithography etching processes through the core technical route of "groove topography constraint + non-through re-etching". By combining the grooved pixel structure design with the lamination / spin-coating process, the present invention innovatively realizes low-damage and high-precision pixelization of thin film materials. The pixelized thin film materials have the technical advantage of small crosstalk, especially in the field of small pixel devices.

[0057] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A manufacturing method of a photoelectric conversion array device, characterized in that, The optoelectronic conversion array device sequentially includes an optoelectronic conversion array, a second carrier transport layer, and a top electrode from bottom to top; the optoelectronic conversion array sequentially includes a dielectric layer, a metal bottom electrode, a first carrier transport layer, an optoelectronic sensing thin film, and an inter-pixel isolation dielectric from bottom to top. A plurality of metal vias are provided in the dielectric layer, and the lower ends of the metal vias are connected to a driving circuit; at least one metal via corresponds to each pixel position of the optoelectronic conversion array device; 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 includes the following process steps: Prepare an optoelectronic conversion array on a substrate and form a trench with an upward opening at each pixel position; Deposit an optoelectronic conversion thin film material in all trenches by spin coating or lamination processes, so that the main part of the optoelectronic conversion thin film material is embedded in the opening trench, and a residual thin film layer is formed on the outer surface of the trench; Adopt a re-etching process to remove the residual thin film layer on the outer surface of the trench to complete the pixelation of the optoelectronic conversion thin film layer; Prepare a second carrier transport layer and a top electrode on the pixelated optoelectronic conversion thin film layer.

2. The method according to claim 1, wherein The depth of the trench matches the thickness of the optoelectronic conversion thin film layer.

3. The method according to claim 2, characterized in that The height range of the trench is 200 nm to 600 nm.

4. The method according to claim 1, wherein The cross-sectional width of the trench is 0.05 to 50 μm.

5. The method according to claim 1, wherein The side wall of the trench is ramp-shaped or vertical.

6. The method according to claim 5, wherein The inclination angle of the side wall of the trench is 40° to 130°.

7. The method according to claim 1, wherein The optoelectronic conversion thin film material includes at least one or a combination of several of organic optoelectronic diode materials, organic light emitting diode materials, or quantum dot materials.

8. The method according to claim 1, characterized in that, The re-etching process uses a dry etching process.

9. The method according to claim 1, wherein The lamination process is a mechanical pressure, a thermal pressure, or an adhesive process based on an auxiliary adhesive.

10. The method according to claim 1, characterized in that The optoelectronic conversion array device is a photosensitive imaging array device or a light emitting array device.

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