Micro display substrate with under-screen sensing function, preparation method and head-mounted display device

Abstract

The present application relates to the technical field of semiconductor micro display, and particularly relates to a micro display substrate with under-screen sensing function, a preparation method and a head-mounted display device, which comprises a silicon-based substrate, a CMOS driving circuit layer integrated in the silicon-based substrate, a pixel array arranged above the CMOS driving circuit layer, the pixel array comprising a plurality of sub-pixel units arranged in an array, a pixel definition layer arranged between adjacent sub-pixel units to define the effective light-emitting area of each sub-pixel, and a photoelectric detection unit arranged in the silicon-based substrate, the photoelectric detection unit arranged in a non-display gap area between adjacent sub-pixel units. The present application utilizes the "dead zone" (i.e. the gap originally used for physical isolation) between sub-pixels to place a photoelectric detector, without occupying the effective light-emitting area of the OLED, so that the original pixel aperture ratio is completely retained while the sensing function is realized, and the display brightness is ensured.

Description

Technical Field

[0001] This invention relates to the field of semiconductor microdisplay technology, specifically to a microdisplay substrate with under-display sensing function, its preparation method, and a head-mounted display device. Background Technology

[0002] With the rapid iteration of augmented reality (AR) and virtual reality (VR) technologies, near-eye display devices are placing higher demands on the resolution, integration, and lightweight design of microdisplay devices. Silicon-based OLED microdisplays, with their advantages of ultra-high pixel density (PPI), high brightness, low power consumption, and fast response speed, have become the mainstream technology in the current near-eye display field.

[0003] To achieve interactive sensing functions such as eye tracking and ambient light sensing, existing AR / VR systems mainly adopt two technical solutions: one is the external infrared camera solution, which adds an independent infrared camera module outside the display module. This solution not only increases the size and weight of the whole device, but also the sensing optical path and the display optical path are not coaxial, requiring complex calibration algorithms to achieve accurate tracking, making it difficult to meet the lightweight and miniaturization development requirements of head-mounted devices; the other is the under-display integration solution, which attempts to integrate photodetectors into the pixels. However, the single pixel size of silicon-based OLEDs is usually less than 10μm. Embedding photosensitive elements in such a small pixel space will directly squeeze the effective light-emitting area of ​​the sub-pixel, resulting in a decrease in pixel aperture ratio. To maintain display brightness, the driving current needs to be increased, which will accelerate the aging of OLED devices and shorten their lifespan, making it difficult to balance high display performance and integrated sensing functions. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a microdisplay substrate with under-display sensing capabilities, a fabrication method, and a head-mounted display device. It combines the advantages of optoelectronic dual isolation and high sensing signal-to-noise ratio without encroaching on the sub-pixel light-emitting area or reducing the pixel aperture ratio. It solves the problems of external infrared camera solutions, such as large size and weight, non-axial optical paths, complex calibration, and difficulty in adapting to lightweight requirements.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A silicon-based OLED microdisplay substrate with under-display sensing function includes a silicon substrate, a CMOS driving circuit layer integrated in the silicon substrate, and a pixel array disposed above the CMOS driving circuit layer. The pixel array includes multiple sub-pixel units arranged in an array. A pixel definition layer is disposed between adjacent sub-pixel units to define the effective light-emitting area of ​​each sub-pixel. A photodetector unit is also disposed in the silicon substrate and is arranged in the non-display gap area between adjacent sub-pixel units.

[0007] The pixel definition layer extends and covers the area above the photoelectric detection unit. The pixel definition layer forms a light transmission area in the region corresponding to the photoelectric detection unit. The light transmission area is transparent to incident light of a preset wavelength, so that external light signals can penetrate and be incident on the photoelectric detection unit.

[0008] An optical isolation structure is provided between the photodetector unit and the adjacent sub-pixel unit. The optical isolation structure is formed by stacking metal interconnect layers and is used to block the lateral stray light emitted by the sub-pixel unit from entering the photodetector unit.

[0009] Preferably, the photoelectric detection unit is surrounded by an electrical isolation structure, which encloses the photoelectric detection unit to block the display driving circuit from transmitting noise to the sensing area through the silicon substrate;

[0010] The electrical isolation structure is one of a deep N-well structure, a deep trench isolation structure, or a silicon-on-insulator structure.

[0011] Preferably, the optical isolation structure is arranged in a closed loop around the circumference of the photodetector unit and penetrates the interlayer dielectric layer in the vertical direction to form an optical well structure, which is used to block the lateral and bottom stray light emitted by the sub-pixel.

[0012] Preferably, the photodetector unit is a photodiode, formed by injecting N-type and P-type impurities into a silicon substrate, and its planar projection falls completely within the range of the non-display gap area.

[0013] Preferably, each of the sub-pixel units is provided with a reflective anode, which is completely hollowed out in the area directly above the photodetector unit. The pixel definition layer fills the hollowed-out area and directly covers the upper surface of the photodetector unit.

[0014] A method for fabricating a silicon-based OLED microdisplay substrate with under-display sensing function includes the following steps:

[0015] S1. Select a single-crystal silicon substrate, use standard CMOS process to prepare CMOS driving circuit layer, and prepare electrical isolation structure in the non-display gap area corresponding to adjacent sub-pixels.

[0016] S2. In the silicon substrate region corresponding to the electrical isolation structure, impurity implantation is performed to form a photodiode, which serves as a photodetector unit;

[0017] S3. Alternating deposition of interlayer dielectric layers and metal interconnect layers, in the peripheral region of the photodetector unit, metal layers and metal vias are stacked to form an optical isolation structure surrounding the photodetector unit;

[0018] S4. After planarization, a reflective anode layer is deposited and patterned etching is performed to form an independent anode corresponding to each sub-pixel. At the same time, the anode layer is completely etched away in the area directly above the photodetector unit to form a light-transmitting window.

[0019] S5. Spin-coating pixel definition layer material, after exposure and development, defines the light-emitting opening area of ​​each sub-pixel, while retaining the pixel definition layer material above the photodetector unit, so that it fills the anode cutout area and covers the photodetector unit to form a light transmission area.

[0020] S6. Sequentially deposit the organic light-emitting layer and the transparent common cathode to complete the thin film encapsulation or cover plate encapsulation.

[0021] Preferably, in step S3, the optical isolation structure penetrates all interlayer dielectric layers in the vertical direction to form a closed optical well structure;

[0022] Before step S4, global planarization is achieved through chemical mechanical polishing, making the top surface of the optical isolation structure flush with the surface of the surrounding dielectric layer.

[0023] Preferably, in step S5, the pixel definition layer is made of fluorinated polyimide material, and the thickness is controlled to be 1.0μm-1.5μm;

[0024] The pixel definition layer blocks light in the visible light band and transmits light in the near-infrared band of 850nm-940nm.

[0025] Preferably, a head-mounted display device includes a device body and a display optical component disposed within the device body. The display optical component includes a silicon-based OLED microdisplay substrate with under-display sensing function. The device body also contains a near-infrared light source and a main control chip.

[0026] The near-infrared light source is used to project near-infrared light of a preset wavelength onto the user's eyes; the silicon-based OLED microdisplay substrate receives the near-infrared light signal reflected back from the user's eyes through its photoelectric detection unit, and converts the light signal into an electrical signal and transmits it to the main control chip.

[0027] The main control chip is electrically connected to the CMOS driving circuit layer of the silicon-based OLED microdisplay substrate and is used to drive each sub-pixel unit to display images.

[0028] The main control chip is also used to process the received photoelectric detection signals to obtain user eye-tracking data.

[0029] By employing the above technical solutions, the present invention provides a microdisplay substrate with under-display sensing function, a fabrication method, and a head-mounted display device, which has at least the following beneficial effects:

[0030] 1. The microdisplay substrate with under-display sensing function, the preparation method and the head-mounted display device utilize the "dead zone" (i.e. the gap originally used for physical isolation) between sub-pixels to place the photodetector, without occupying the effective light-emitting area of ​​the OLED. Therefore, while realizing the sensing function, the original pixel aperture ratio is completely preserved, ensuring the display brightness.

[0031] 2. The microdisplay substrate with under-display sensing function, its fabrication method, and the head-mounted display device integrate "display" and "sensing" at the wafer level, eliminating the need for an external, separate infrared camera module and significantly reducing the size of AR / VR glasses.

[0032] 3. The microdisplay substrate with under-display sensing function, its preparation method, and the head-mounted display device are different from anti-interference schemes that rely solely on timing control. This invention achieves directional conduction and isolation of the optical path at the physical level through the combination of a "metal optical isolation structure" and a "PDL light-transmitting window". At the same time, in conjunction with circuit isolation technology, it significantly improves the signal-to-noise ratio (SNR) and detection accuracy of the sensor. Attached Figure Description

[0033] The accompanying drawings, which are provided to further illustrate the invention, constitute a part of this application:

[0034] Figure 1 This is a partial top view of the silicon-based OLED display substrate of the present invention;

[0035] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure along section A-A'.

[0036] Figure 3 This is a circuit block diagram illustrating the display driving and sensor readout of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure of the device body of the present invention.

[0038] Figure label:

[0039] 1. Pixel definition layer; 2. Subpixel unit; 3. Photodetector unit; 4. Optical isolation structure; 5. Silicon substrate; 6. Display driving system; 7. Reflective anode; 8. Transparent common cathode; 9. Electrical isolation structure; 10. Interlayer dielectric layer; 11. Sensing readout system; 12. Main control chip; 13. Device body; 14. Near-infrared light source. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The following description, in conjunction with the accompanying drawings, describes some embodiments of the present invention, including a microdisplay substrate with under-display sensing function, a fabrication method, and a head-mounted display device.

[0042] Example 1:

[0043] Combination Figure 1 and Figure 2 As shown, the present invention provides a micro-display substrate with under-display sensing function, a fabrication method, and a head-mounted display device, including a silicon substrate 5, a CMOS driving circuit layer integrated in the silicon substrate 5, and a pixel array disposed above the CMOS driving circuit layer. The pixel array includes multiple sub-pixel units 2 arranged in an array. A pixel definition layer 1 is disposed between adjacent sub-pixel units 2 to define the effective light-emitting area of ​​each sub-pixel. A photodetector unit 3 is also disposed in the silicon substrate 5. The photodetector unit 3 is arranged in the non-display gap area between adjacent sub-pixel units 2. The photodetector unit 3 is completely arranged in the non-display gap between sub-pixels, without occupying any effective light-emitting area of ​​the sub-pixels. While adding under-display sensing function, the original pixel aperture ratio is completely preserved, avoiding problems such as brightness reduction and driving current increase, and ensuring the service life of OLED devices.

[0044] The pixel definition layer 1 extends and covers the photodetector unit 3. The pixel definition layer 1 forms a light transmission area in the area corresponding to the photodetector unit 3. The light transmission area is transparent to incident light of a preset wavelength band, so that external light signals can pass through and enter the photodetector unit 3. The pixel definition layer 1 is reused as a light transmission window, so there is no need to prepare a special transparent film layer. It is highly compatible with conventional silicon-based OLED manufacturing processes and will not significantly increase the process complexity and production cost.

[0045] A light isolation structure 4 is provided between the photodetector unit 3 and the adjacent sub-pixel unit 2. The light isolation structure 4 is formed by stacking metal interconnect layers and is used to block the lateral stray light emitted by the sub-pixel unit 2 from entering the photodetector unit 3. It directly blocks the lateral stray light emitted by the sub-pixel at the physical level, reduces the crosstalk of the display light to the sensing signal from the source of the optical path, and greatly improves the signal-to-noise ratio of photodetector.

[0046] Specifically, an electrical isolation structure 9 is provided around the photoelectric detection unit 3. The electrical isolation structure 9 encloses the photoelectric detection unit 3 to block the transmission of noise from the display driving circuit to the sensing area through the silicon substrate 5. It forms an enclosed electrical shield for the photoelectric detection unit 3 at the silicon substrate level, physically cutting off the path of high-voltage switching noise of the display driving circuit to the sensing area through the silicon substrate, significantly reducing the noise floor of the sensing signal, and improving the detection accuracy and stability of weak photocurrent.

[0047] The electrical isolation structure 9 is one of the following: deep N-well structure, deep trench isolation structure, or silicon-on-insulator structure, which can be adapted to CMOS production lines with different process nodes and different process platforms.

[0048] Furthermore, the optical isolation structure 4 is arranged in a closed loop around the photoelectric detection unit 3 and penetrates the interlayer dielectric layer 10 in the vertical direction to form an optical well structure, which is used to block the side and bottom stray light emitted by the sub-pixel. It can block the side light, oblique light and diffuse stray light reflected from the bottom of the dielectric layer emitted by the sub-pixel in all directions, thereby suppressing optical crosstalk and further improving the signal-to-noise ratio of photoelectric sensing.

[0049] The photodetector unit 3 is a photodiode, formed by injecting N-type and P-type impurities into the silicon substrate 5. Its planar projection falls completely within the range of the non-display gap area. It is compatible with the fabrication process of silicon-based driving circuits and does not require the introduction of additional processes such as heterogeneous integration and bonding. It can be mass-produced by relying on existing mature production lines.

[0050] Each sub-pixel unit 2 is provided with a corresponding reflective anode 7. The reflective anode 7 is completely hollowed out in the area directly above the photodetector unit 3. The pixel definition layer 1 fills the hollowed-out area and directly covers the upper surface of the photodetector unit 3. Removing the reflective anode 7 directly above the photodetector unit 3 eliminates the obstruction of incident light by the opaque anode metal, ensuring that external light signals can reach the photodiode efficiently, thereby improving light reception efficiency and sensing sensitivity.

[0051] Example 2:

[0052] Combination Figure 1 and Figure 2 As shown, based on Embodiment 1, a method for fabricating a silicon-based OLED microdisplay substrate with under-display sensing function includes the following steps:

[0053] S1. Select a single-crystal silicon substrate, use standard CMOS process to prepare CMOS driving circuit layer, prepare electrical isolation structure 9 in the non-display gap area corresponding to adjacent sub-pixels, form electrical isolation structure 9 inside the silicon substrate to wrap the sensing area, and physically separate the sensing area from the display driving area at the substrate level.

[0054] S2. In the silicon substrate region corresponding to the electrical isolation structure 9, impurity implantation is performed to form a photodiode, which serves as the photodetector unit 3. Its position is strictly limited within the pixel gap, and it does not occupy the light-emitting area of ​​the sub-pixel at all, ensuring that the pixel aperture ratio is not affected from the process level.

[0055] S3. Alternating deposition of interlayer dielectric layer 10 and metal interconnect layer. In the area surrounding photodetector unit 3, metal layer and metal via are stacked to form optical isolation structure 4 around photodetector unit 3. Based on existing technology, optical isolation structure 4 can be prepared simultaneously by only adjusting the layout, without adding photolithography layers and process steps, and without adding extra manufacturing costs.

[0056] S4. After planarization, a 7-layer reflective anode is deposited and patterned to form an independent anode for each sub-pixel. At the same time, the anode layer is completely etched and removed in the area directly above the photodetector unit 3 to form a light-transmitting window. The reflective anode 7 can reflect the light emitted downward by the OLED upward, effectively improving the light extraction efficiency and display brightness of the sub-pixel.

[0057] S5. Spin-coating pixel definition layer 1 material, after exposure and development, defines the light-emitting opening area of ​​each sub-pixel, while retaining the pixel definition layer 1 material above the photodetector unit 3, so that it fills the anode cutout area and covers the photodetector unit 3, forming a light transmission area.

[0058] S6. Sequentially deposit the organic light-emitting layer and the transparent common cathode 8 to complete the thin film encapsulation or cover glass encapsulation. Using a vacuum evaporation process, the entire surface is sequentially deposited with the OLED organic light-emitting layer and the ultra-thin transparent common cathode 8. Finally, water and oxygen barrier is completed through thin film encapsulation or cover glass encapsulation.

[0059] Specifically, the optical isolation structure 4 penetrates the entire interlayer dielectric layer 10 in the vertical direction to form a closed optical well structure. Before step S4, global planarization is achieved by chemical mechanical polishing, so that the top surface of the optical isolation structure 4 is flush with the surface of the surrounding dielectric layer. The closed optical well that penetrates the entire layer can block side light, oblique light and diffuse stray light reflected by the dielectric layer in all directions. The optical crosstalk suppression effect is far better than that of a single-layer metal structure, which significantly improves the sensing signal-to-noise ratio.

[0060] Furthermore, the pixel definition layer 1 uses fluorinated polyimide material with a thickness controlled between 1.0 μm and 1.5 μm. In the molecular structure of fluorinated polyimide, the fluorine groups can reduce the material's light absorption in the near-infrared band; at the same time, the intrinsic properties of the material determine that it has strong light absorption in the visible light band. The thickness is controlled in the range of 1.0 μm to 1.5 μm, which is the optimal range that balances insulation performance, step coverage, and infrared transmittance.

[0061] The pixel definition layer 1 blocks light in the visible light band and transmits light in the 850nm-940nm near-infrared band, which can ensure that the photocurrent responsivity of the photodiode is maintained above 0.4A / W, meeting the signal sensitivity requirements of scenarios such as eye tracking.

[0062] Example 3:

[0063] Combination Figure 1 and Figure 4 As shown, based on Embodiment 1, a head-mounted display device includes a device body 13 and a display optical component disposed within the device body 13. The display optical component includes a silicon-based OLED microdisplay substrate with under-display sensing function. The device body 13 is also provided with a near-infrared light source 14 and a main control chip 12.

[0064] The near-infrared light source 14 is used to project near-infrared light of a preset wavelength onto the user's eyes; the silicon-based OLED microdisplay substrate receives the near-infrared light signal reflected back from the user's eyes through its photoelectric detection unit 3, and converts the light signal into an electrical signal and transmits it to the main control chip 12.

[0065] The main control chip 12 is electrically connected to the CMOS driving circuit layer of the silicon-based OLED microdisplay substrate and is used to drive each sub-pixel unit 2 to display images;

[0066] The main control chip 12 is also used to process the received photoelectric detection electrical signals to obtain user eye tracking data. The display imaging link and the eye tracking sensing link rely on the same micro display substrate to achieve optical path coaxiality. The two can work synchronously and in parallel, or the timing control of the main control chip 12 can be used to adopt time division multiplexing mode to further reduce crosstalk. Thanks to the wafer-level monolithic integrated structure design, the whole system does not require an external independent infrared camera and complex optical path calibration algorithm. While achieving high-precision eye tracking, it effectively compresses the size and weight of the display module, adapting to the lightweight design requirements of head-mounted display devices.

[0067] Example 4:

[0068] Combination Figure 3 As shown, based on Embodiment 1, this head-mounted display device uses a single-chip integrated under-screen sensor silicon-based OLED substrate as its core. The main control chip 12 is bidirectionally connected to the display driving system 6 and the sensor readout system 11, respectively, and uniformly schedules the coordinated operation of the two links.

[0069] In the display link, the main controller outputs image data and timing signals to the display driving system 6. These signals are then driven by the gate and source driving circuits to illuminate the OLED sub-pixels in the pixel array area. Photodiodes are positioned between the pixels, not occupying the luminous area and thus not compromising display performance. In the sensing link, a near-infrared light source 14 illuminates the eyeball. The reflected light passes through the light transmission area of ​​the pixel definition layer 1 and is converted into an electrical signal by the photodiode. The photodiode output is connected to the sensing readout system 11, and after charge amplification and analog-to-digital conversion, the signal is transmitted back to the main control chip 12 to calculate the eye movement data.

[0070] The metal optical isolation structure surrounding the photodiode blocks stray light from the display, and the deep N-well electrical isolation region shields the substrate noise of the driving circuit, thus doubly improving the sensing signal-to-noise ratio. This solution is compatible with standard CMOS processes, eliminates the need for an external infrared camera, balances display quality and sensing accuracy, and can effectively reduce the size and weight of the module, meeting the lightweight requirements of head-mounted devices.

[0071] It should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A silicon-based OLED microdisplay substrate with under-display sensing function, comprising a silicon substrate (5), a CMOS driving circuit layer integrated within the silicon substrate (5), and a pixel array disposed above the CMOS driving circuit layer, the pixel array comprising a plurality of sub-pixel units (2) arranged in an array, wherein a pixel definition layer (1) is disposed between adjacent sub-pixel units (2) to define the effective light-emitting area of ​​each sub-pixel, characterized in that: The silicon substrate (5) is also provided with a photoelectric detection unit (3), which is arranged in the non-display gap area between adjacent sub-pixel units (2); The pixel definition layer (1) extends over the photoelectric detection unit (3). The pixel definition layer (1) forms a light transmission area in the area corresponding to the photoelectric detection unit (3). The light transmission area is transparent to incident light of a preset wavelength band and is used to allow external light signals to penetrate and be incident on the photoelectric detection unit (3). A light isolation structure (4) is provided between the photodetector unit (3) and the adjacent sub-pixel unit (2). The light isolation structure (4) is formed by stacking metal interconnect layers and is used to block the lateral stray light emitted by the sub-pixel unit (2) from entering the photodetector unit (3).

2. The silicon-based OLED microdisplay substrate with under-display sensing function according to claim 1, characterized in that, An electrical isolation structure (9) is provided around the photoelectric detection unit (3). The electrical isolation structure (9) encloses the photoelectric detection unit (3) to block the display driving circuit from transmitting noise to the sensing area through the silicon substrate (5). The electrical isolation structure (9) is one of a deep N-well structure, a deep trench isolation structure, or a silicon-on-insulator structure.

3. The silicon-based OLED microdisplay substrate with under-display sensing function according to claim 1, characterized in that, The optical isolation structure (4) is arranged to surround the photoelectric detection unit (3) in a closed manner and penetrates the interlayer dielectric layer (10) in the vertical direction to form an optical well structure, which is used to block the side and bottom stray light emitted by the sub-pixel.

4. The silicon-based OLED microdisplay substrate with under-display sensing function according to claim 1, characterized in that, The photodetector unit (3) is a photodiode, formed by injecting N-type and P-type impurities into a silicon substrate (5), and its planar projection falls completely within the range of the non-display gap area.

5. The silicon-based OLED microdisplay substrate with under-display sensing function according to claim 1, characterized in that, Each of the sub-pixel units (2) is provided with a reflective anode (7). The reflective anode (7) is completely hollowed out in the area directly above the photoelectric detection unit (3). The pixel definition layer (1) fills the hollowed-out area and directly covers the upper surface of the photoelectric detection unit (3).

6. A method for fabricating a silicon-based OLED microdisplay substrate with under-display sensing function, characterized in that, Includes the following steps: S1. Select a single-crystal silicon substrate and use standard CMOS process to prepare CMOS driving circuit layer. Prepare electrical isolation structure in the non-display gap area corresponding to adjacent sub-pixels (9). S2. In the silicon substrate region corresponding to the electrical isolation structure (9), impurity implantation is performed to form a photodiode, which serves as a photodetector unit (3). S3. Alternating deposition of interlayer dielectric layer (10) and metal interconnect layer, in the peripheral area of ​​photodetector unit (3), metal layer and metal via stacking are used to form an optical isolation structure (4) surrounding the photodetector unit (3). S4. After planarization, a reflective anode (7) layer is deposited and patterned etching is performed to form an independent anode corresponding to each sub-pixel. At the same time, the anode layer is completely etched away in the area directly above the photodetector unit (3) to form a light-transmitting window. S5. Spin-coating pixel definition layer (1) material, after exposure and development, defines the light-emitting opening area of ​​each sub-pixel, while retaining the pixel definition layer (1) material above the photodetector unit (3), so that it fills the anode hollow area and covers the photodetector unit (3) to form a light transmission area; S6. Sequentially deposit the organic light-emitting layer and the transparent common cathode (8) to complete the thin film encapsulation or cover plate encapsulation.

7. The preparation method according to claim 6, characterized in that, In step S3, the optical isolation structure (4) penetrates all the interlayer dielectric layers (10) in the vertical direction to form a closed optical well structure; Before step S4, global planarization is achieved by chemical mechanical polishing, so that the top surface of the optical isolation structure (4) is flush with the surface of the surrounding dielectric layer.

8. The preparation method according to claim 6, characterized in that, In step S5, the pixel definition layer (1) is made of fluorinated polyimide material and the thickness is controlled to be 1.0μm-1.5μm; The pixel definition layer (1) blocks light in the visible light band and transmits light in the near-infrared band of 850nm-940nm.

9. A head-mounted display device, comprising a device body (13) and display optical components disposed within the device body (13), characterized in that: The display optical component includes a silicon-based OLED microdisplay substrate with under-display sensing function as described in any one of claims 1-5, and the device body (13) is further provided with a near-infrared light source (14) and a main control chip (12). The near-infrared light source (14) is used to project near-infrared light of a preset wavelength onto the user's eyes; the silicon-based OLED micro-display substrate receives the near-infrared light signal reflected back from the user's eyes through its photoelectric detection unit (3), and converts the light signal into an electrical signal and transmits it to the main control chip (12). The main control chip (12) is electrically connected to the CMOS driving circuit layer of the silicon-based OLED microdisplay substrate and is used to drive each sub-pixel unit (2) to display images. The main control chip (12) is also used to process the received photoelectric detection electrical signals to obtain user eye-tracking data.

Images