HEMT driving and microled integrated back plate and manufacturing method therefor

Abstract

An HEMT driving and MicroLED integrated back plate and a manufacturing method therefor, relating to the field of MicroLED. The manufacturing method comprises the steps: growing an HEMT epitaxial structure on a substrate; successively growing three monochromatic LED epitaxial structures on the HEMT epitaxial structure to obtain an epitaxial wafer; etching to the substrate for partitioning of the epitaxial wafer; and depositing a passivation layer, etching a through hole, and then depositing a conductor, so that n-GaN layers of three LED regions are connected and connected to one HEMT region, and the remaining three HEMT regions are respectively connected to a p-GaN layer of one LED region. An HEMT and a three-color LED device are integrated on a single substrate at an epitaxial end, so that the effect of parasitic parameters caused by complex packaging and bonding processes can be avoided, and tedious mass transfer and detection procedures after mass transfer can be skipped.

Description

HEMT-driven MicroLED integrated backplane and manufacturing method thereof Technical Field

[0001] The present invention relates to a HEMT-driven MicroLED integrated backplane and a manufacturing method thereof, and belongs to the field of MicroLED. Background Art

[0002] MicroLEDs have attracted considerable attention due to their high luminous efficiency, high reliability, and excellent response speed. Compared to LCD and OLED displays, which currently dominate the market, MicroLEDs hold enormous potential in realizing high-resolution, high-refresh-rate AR, VR, and large-size tiled displays for display applications.

[0003] Compared to traditional PM (passive-address drive) luminescence, AM (active-address drive) uses a pixel circuit composed of TFTs (thin-film field-effect transistors) and capacitors to drive the light-emitting device. Each pixel is controlled by an independent switching transistor. This is of great significance for high-resolution and large-size displays, breaking through the limitations of the number of rows in the luminescence mode. Furthermore, the charging and discharging process of the capacitors can compensate for errors in the TFT threshold voltage and mobility manufacturing process, ensuring more stable display panel operation. The TFT-based AM drive method has long been proven and applied in LCD and OLED displays. However, unlike the former, microLEDs are sensitive to current fluctuations. First, attempts to control microLED brightness through current fluctuations result in significant drift in the center wavelength of the emission. Second, the nonlinear relationship between the injected current and the grayscale spread of the microLEDs creates certain difficulties in driving and controlling them. HEMT (High Electron Mobility Transistor) is based on the third-generation semiconductor GaN material system and has excellent electron mobility, switching ratio and other electrical properties suitable for enhancing display performance. Compared with TFT devices, HEMT's unique high-voltage characteristics can ensure the panel's tolerance and reliability under extreme conditions. Its excellent high-frequency characteristics are conducive to high refresh rate display application scenarios.

[0004] Applying HEMTs to MicroLEDs is a major challenge in this field. Transfer bonding technology has long been a key impediment to MicroLED industrialization. Two mainstream research directions are currently highly sought after: First, processing the processed LED wafers and CMOS driver backplanes, then connecting them via wafer bonding. This method is efficient and simple to use, but is unsuitable for large-scale displays due to wafer size constraints. Furthermore, integrating RGB LEDs on the same epitaxial wafer is difficult, limiting its ability to achieve full-color displays. Second, using a mass transfer method, separate RGB wafers are prepared. Then, using stamping and laser transfer, combined with wafer-level inspection and repair systems, batches of RGB LED chips are transferred to the corresponding solder joints on the backplane for bonding. This method is suitable for large-scale panels and full-color displays, but is cumbersome and poses challenges in ensuring yield and efficiency. Furthermore, both approaches are significantly affected by the bonding process, which results in varying circuit parasitic parameters, which inevitably impact high refresh rate and high-resolution displays. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention provides a HEMT-driven MicroLED integrated backplane and a manufacturing method thereof, which directly integrates the HEMT and the RGB three-color MicroLED at the epitaxial growth end to avoid the parasitic parameter effects caused by the complicated and inefficient transfer bonding steps.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] In a first aspect, the present application provides a method for manufacturing a HEMT-driven MicroLED integrated backplane, comprising the following steps:

[0008] growing a HEMT epitaxial structure on a substrate;

[0009] Three monochromatic LED epitaxial structures are sequentially stacked and grown on the HEMT epitaxial structure to obtain an epitaxial wafer; a third u-GaN layer is grown between the bottommost monochromatic LED epitaxial structure and the HEMT epitaxial structure, and a fourth u-GaN layer is grown between adjacent monochromatic LED epitaxial structures, wherein each monochromatic LED epitaxial structure comprises, from bottom to top, an n-GaN layer, a multi-quantum well layer, and a p-GaN layer;

[0010] Etching the substrate to partition the epitaxial wafer; the etched epitaxial wafer includes: three LED regions each exposing one of the monochromatic LED epitaxial structures and four HEMT regions where the structure above the third u-GaN layer is removed;

[0011] A passivation layer is deposited, through holes are etched, and conductors are deposited to connect the n-GaN layers of three LED regions to one HEMT region, and the remaining three HEMT regions are each connected to the p-GaN layer of one LED region.

[0012] Those skilled in the art understand that u-GaN refers to unintentionally doped gallium nitride, n-GaN refers to n-type doped gallium nitride, and p-GaN refers to p-type doped gallium nitride.

[0013] The manufacturing method of the HEMT-driven MicroLED integrated backplane provided in this application is conducive to ensuring the performance of the HEMT device, enabling it to exhibit the characteristics of high mobility and low leakage current in the overall driving circuit, which is conducive to high refresh rate display.

[0014] Furthermore, the HEMT epitaxial structure includes a buffer layer, a second u-GaN layer and an Al 0.3 Ga 0.7 N layers.

[0015] Al 0.3 Ga 0.7 A two-dimensional electron gas is formed at the N / u-GaN interface. The electrons that can move are confined to an area of ​​about a few nanometers at the top of the u-GaN layer below the interface. The electrons are confined in this area and cannot move in the third dimension, resulting in a very small scattering intensity and good electron mobility.

[0016] Furthermore, the buffer layer includes a first u-GaN layer and an Al 0.15 Ga 0.85 N layer, the Al 0.15 Ga 0.85 The thickness of the N layer is 50nm-60nm.

[0017] The first u-GaN layer and Al 0.15 Ga 0.85 The N layer helps alleviate lattice mismatch, lays a good foundation for the subsequent growth of multi-layer structures, and helps improve the quality of epitaxial wafers.

[0018] Furthermore, the second u-GaN layer and the Al 0.3 Ga 0.7 There is also an AlN layer between the N layers. 0.3 Ga 0.7 The thickness of the N layer is 15 nm to 25 nm, and the thickness of the AlN layer is 0.5 nm to 8 nm.

[0019] In Al 0.3 Ga 0.7 A thin layer of aluminum nitride is inserted at the N / u-GaN interface, and AlN participates in forming a heterojunction, which can improve electron mobility.

[0020] Furthermore, the thickness of the fourth u-GaN layer is 500nm-600nm.

[0021] The adjacent two layers of LEDs have current injection of the same polarity, which makes them easy to conduct in the forward direction. The fourth u-GaN layer is used to isolate the adjacent monochromatic LED epitaxial structures. In this application, the fourth u-GaN layer is made thicker, that is, 500nm-600nm, so that the monochromaticity of the LED light emission is not affected when current injection occurs.

[0022] Furthermore, the third u-GaN layer has a thickness of 150 nm to 180 nm.

[0023] In this application, the epitaxial layer structure is more and thicker. In a preferred embodiment, the HEMT epitaxial structure includes the first u-GaN layer, the Al 0.15 Ga 0.85 N layer, a second u-GaN layer, an AlN layer and the Al 0.3 Ga 0.7 The thickness of the fourth u-GaN layer is 500nm-600nm, making the overall thickness of the epitaxial wafer even greater. The third u-GaN layer serves to isolate the HEMT from the bottom LED. The current of the HEMT and the current of the LED are injected separately with different polarities. Making the third u-GaN layer as thin as possible, that is, 150nm-180nm thick, helps to minimize the overall thickness of the epitaxial wafer while ensuring the isolation effect. In addition, the steps of the method of the application require etching to the substrate when partitioning. When setting the source, gate, and drain of the HEMT, it is also necessary to etch the third u-GaN layer to the HEMT area. Making the third u-GaN layer as thin as possible helps to reduce the difficulty of subsequent processes.

[0024] Furthermore, the step of etching the substrate to partition the epitaxial wafer includes:

[0025] depositing silicon dioxide on the surface of the epitaxial wafer to form a first hard mask;

[0026] Photolithographically forming a patterned first soft mask on the first hard mask, where the first soft mask covers a first preset sub-pixel area;

[0027] Etching until the first hard mask is completely removed, so as to expose the highest p-GaN layer of the monochromatic LED epitaxial structure in the first predetermined sub-pixel region and expose the p-GaN layer of the monochromatic LED epitaxial structure located in the middle at the remaining positions;

[0028] depositing silicon dioxide on the surface of the epitaxial wafer to form a second hard mask;

[0029] Photolithographically forming a patterned second soft mask on the second hard mask, wherein the second soft mask covers the first preset sub-pixel region and the second preset sub-pixel region;

[0030] Etching until the second hard mask is completely removed to expose the p-GaN layer of the highest monochromatic LED epitaxial structure in the first predetermined sub-pixel region, expose the p-GaN layer of the middle monochromatic LED epitaxial structure in the second predetermined sub-pixel region, and expose the p-GaN layer of the bottom monochromatic LED epitaxial structure (taking the three monochromatic LED epitaxial structures above the HEMT epitaxial structure emitting red, green, and blue light in sequence as an example, "highest" refers to the monochromatic LED epitaxial structure emitting blue light, "middle" refers to the monochromatic LED epitaxial structure emitting green light, and "bottom" refers to the monochromatic LED epitaxial structure emitting red light) at other locations;

[0031] A patterned third soft mask is formed by photolithography on the surface of the epitaxial wafer, wherein the coverage of the third soft mask is the first preset sub-pixel area, the second preset sub-pixel area, the third preset sub-pixel area and four preset driving areas;

[0032] The epitaxial wafer is etched to expose the highest p-GaN layer of the monochromatic LED epitaxial structure in the first predetermined sub-pixel region, expose the middle p-GaN layer of the monochromatic LED epitaxial structure in the second predetermined sub-pixel region, expose the bottommost p-GaN layer of the monochromatic LED epitaxial structure in the third predetermined sub-pixel region, and expose the top surface of the HEMT epitaxial structure in the predetermined driving region. The remaining positions are deep into the substrate. The first predetermined sub-pixel region, the second predetermined sub-pixel region, and the third predetermined sub-pixel region independently become the LED region, and the predetermined driving region becomes the HEMT region.

[0033] In this application, the epitaxial wafer structure is complex and thick. If only photoresist is used, the thickness of the photoresist has an engineering limit, and the etching selectivity between the photoresist and GaN is insufficient. The photoresist is etched away before the target depth is reached. This application uses a combination of hard and soft masks and etches in multiple steps to ensure etching completeness and overcome the difficulties caused by insufficient etching selectivity in the etching process.

[0034] Furthermore, a thickness ratio of the first hard mask to the first soft mask is 5-7:1, and a thickness ratio of the second hard mask to the second soft mask is 5-7:1.

[0035] Unlike photoresist, silicon dioxide cannot be easily separated from gallium nitride by chemical methods. When the thickness of the fourth u-GaN layer is 500nm-600nm, the thickness of the hard mask is set to 500nm-700nm and the thickness of the soft mask is set to 100nm. This is beneficial for not penetrating the p-GaN layer on the step when etching away all the silicon dioxide.

[0036] Furthermore, in each of the monochromatic LED epitaxial structures, an electron blocking layer is grown between the multi-quantum well layer and the p-GaN layer.

[0037] In a second aspect, the present application provides a HEMT-driven Micro-LED integrated backplane, manufactured using the method described in aspect 1. This backplane directly integrates the HEMT and three-color Micro-LED at the epitaxial growth end, avoiding the parasitic parameter effects caused by the complex and inefficient transfer bonding step.

[0038] The present invention has the following beneficial effects: the epitaxial layer preparation sequence employed in the present invention is conducive to ensuring the performance of the HEMT device, enabling it to exhibit the characteristics of high mobility and low leakage current in the overall drive circuit, facilitating high refresh rate displays. Three-color LEDs are connected in parallel with a common N-pole, and the overall brightness can be adjusted by adjusting the total driving HEMT voltage. Adjusting the voltage of each branch HEMT allows for independent control of the three-color LEDs. The present invention integrates the HEMT and three-color LED devices on a single substrate at the epitaxial end, avoiding the influence of parasitic parameters caused by complex packaging and bonding processes, and bypassing the cumbersome mass transfer and post-mass transfer testing processes. This has certain significance for breaking through the bottleneck of the Micro-LED panel industrialization.

[0039] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures particularly pointed out in the written description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a flow chart of a method for manufacturing a HEMT-driven MicroLED integrated backplane according to an embodiment of the present application.

[0041] FIG2 is a schematic structural diagram of a HEMT-driven MicroLED integrated backplane provided in an embodiment of the present application.

[0042] FIG3 is a flowchart showing the specific steps of step S3.

[0043] Reference numerals: 1, substrate; 2, HEMT region; 21, first u-GaN layer; 22, Al 0.15 Ga 0.85N layer; 23, second u-GaN layer; 24, AlN layer; 25, Al 0.3 Ga 0.7 N layer; 26, drain; 27, gate; 28, source; 3, third u-GaN layer; 4, LED region; 41, n-GaN layer; 42, multi-quantum well layer; 43, electron blocking layer; 44, p-GaN layer; 45, fourth u-GaN layer; 5, passivation layer; 51, cathode conductor; 52, anode conductor; 61, first hard mask; 62, first soft mask; 63, third soft mask. DETAILED DESCRIPTION

[0044] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0045] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and configurations of specific examples are described below. Of course, these are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or configurations discussed.

[0046] The epitaxial growth process of HEMT and GaN-based RGB three-color LED chips is based on the same system. It is expected that HEMT and RGB three-color Micro-LED can be directly integrated at the epitaxial growth end to overcome problems that cannot be solved by wafer bonding and mass transfer.

[0047] 1 , an embodiment of the present application provides a method for manufacturing a HEMT-driven MicroLED integrated backplane, comprising the following steps:

[0048] S1: growing a HEMT epitaxial structure on a substrate 1. The substrate 1 may be, for example, sapphire.

[0049] S2: Three monochromatic LED epitaxial structures are sequentially stacked and grown on the HEMT epitaxial structure to obtain an epitaxial wafer.

[0050] A third u-GaN layer 3 is grown between the bottommost monochromatic LED epitaxial structure and the HEMT epitaxial structure, and a fourth u-GaN layer 45 is grown between adjacent monochromatic LED epitaxial structures. Each monochromatic LED epitaxial structure comprises, from bottom to top, an n-GaN layer 41, a multi-quantum well layer 42, and a p-GaN layer 44. The three monochromatic colors can be blue, red, or green, and the specific color can be adjusted by the indium content of the multi-quantum well layer 42.

[0051] S3: Etching to the substrate 1 to partition the epitaxial wafer.

[0052] The method comprises: three LED regions 4 each exposing one type of monochromatic LED epitaxial structure and four HEMT regions 2 with the structure above the third u-GaN layer 3 removed;

[0053] S4: Deposit a passivation layer 5 , etch through holes, and then deposit conductors to connect the n-GaN layers 41 of three LED regions 4 to one HEMT region 2 , and the remaining three HEMT regions 2 to each of the p-GaN layers 44 of one LED region 4 .

[0054] The final HEMT-driven MicroLED integrated backplane is shown in Figure 2, which includes four HEMT regions 2 and three LED regions 4 on a substrate 1. The three LED regions 4 have different thicknesses (or heights). The thickest LED region 4 has three monochromatic LED epitaxial structures, the second thickest LED region 4 has two monochromatic LED epitaxial structures, and the thinnest LED region 4 has one monochromatic LED epitaxial structure. In each of the three LED regions 4, only the topmost monochromatic LED epitaxial structure is turned on, and the n-GaN layer 41 is partially exposed in the topmost monochromatic LED epitaxial structure. Specifically, the HEMT includes a source 28, a gate 27, and a drain 26 (the fabrication of source 28, gate 27, and drain 26 is conventional technology, and this application does not discuss the specific pixel circuit design). The n-GaN layers 41 of three LED regions 4 are connected via a cathode conductor 51 and are also connected to the source 28 of one HEMT region 2. Of the sources 28 of the remaining three HEMT regions 2, one is connected to the p-GaN layer 44 of the red-emitting LED region 4 via an anode conductor 52, one is connected to the p-GaN layer 44 of the blue-emitting LED region 4 via an anode conductor 52, and one is connected to the p-GaN layer 44 of the green-emitting LED region 4 via an anode conductor 52. These three anode conductors 52 are not connected. In this manner, the three color LEDs are connected in parallel with a common N-pole. Adjusting the total HEMT driving voltage adjusts the overall brightness, and adjusting the voltage of each branch HEMT allows for individual control of the three color LEDs.

[0055] The epitaxial layer preparation sequence used in the embodiments of the present application is conducive to ensuring the performance of the HEMT device, enabling it to exhibit the characteristics of high mobility and low leakage current in the overall drive circuit, which is conducive to high refresh rate display. Integrating the HEMT and the three-color LED device on a single substrate 1 at the epitaxial end can avoid the influence of parasitic parameters caused by complex packaging and bonding processes, and can bypass the tedious mass transfer and post-mass transfer inspection processes.

[0056] In some embodiments, the HEMT epitaxial structure includes a buffer layer, a second u-GaN layer 23 and an Al 0.3 Ga 0.7 N layer 25. Al 0.3 Ga 0.7 A two-dimensional electron gas is formed at the N / u-GaN interface. The electrons that can move are confined to an area of ​​about a few nanometers at the top of the u-GaN layer below the interface. The electrons are confined in this area and cannot move in the third dimension, resulting in a very small scattering intensity and good electron mobility.

[0057] As shown in FIG1 , the buffer layer includes the first u-GaN layer 21 and the Al 0.15 Ga 0.85 N layer 22, Al 0.15 Ga 0.85 The thickness of the N layer 22 is 50nm-60nm (the figures in the specification are only for the purpose of illustrating the layer structure and connection structure, and the thickness ratio and area size ratio may not be consistent with the actual situation). 0.15 Ga 0.85 The N layer 22 is helpful in alleviating lattice mismatch, laying a good foundation for the subsequent growth of multi-layer structures, and improving the quality of epitaxial wafers.

[0058] As shown in FIG1 , the second u-GaN layer 23 and the Al 0.3 Ga 0.7 There is also an AlN layer 24 between the N layer 25. 0.3 Ga 0.7 The thickness of the N layer 25 is 15nm-25nm, and the thickness of the AlN layer 24 is 0.5nm-8nm. 0.3 Ga 0.7 A thin layer of aluminum nitride is inserted at the N / u-GaN interface, and AlN participates in forming a heterojunction, which can improve electron mobility.

[0059] The adjacent two layers of LEDs have current injection of the same polarity, which makes them easy to conduct in the forward direction. The fourth u-GaN layer 45 is used to isolate the adjacent monochromatic LED epitaxial structures. In this application, the fourth u-GaN layer 45 is made thicker, that is, 500nm-600nm, so that the monochromaticity of the LED light emission is not affected when current injection occurs, further reducing leakage.

[0060] In combination with the above preferred embodiments, the HEMT epitaxial structure includes, from bottom to top, the first u-GaN layer 21, the Al 0.15 Ga 0.85 N layer 22, second u-GaN layer 23, AlN layer 24 and Al 0.3 Ga 0.7 The thickness of the N layer 25 and the fourth u-GaN layer 45 is 500nm-600nm, resulting in a relatively thick epitaxial wafer. Furthermore, the third u-GaN layer 3 is 150nm-180nm thick, which helps minimize the overall thickness of the epitaxial wafer while ensuring isolation. Furthermore, in step S3, etching down to the substrate 1 is required. When providing the source 28, gate 27, and drain 26 for the HEMT, the third u-GaN layer 3 also needs to be etched down to the HEMT region 2. Making the third u-GaN layer 3 as thin as possible helps reduce the difficulty of subsequent processing.

[0061] Referring to FIG3 , the specific steps of step S3 include:

[0062] S31 : depositing silicon dioxide on the surface of the epitaxial wafer to form a first hard mask 61 .

[0063] S32: A patterned first soft mask 62 is formed on the first hard mask by photolithography, and the first soft mask 62 covers the first predetermined sub-pixel region. After this step is completed, the second image in FIG3 is shown in the order of arrows.

[0064] S33: Etching until the first hard mask is completely removed to expose the highest p-GaN layer 44 of the monochromatic LED epitaxial structure in the first predetermined sub-pixel region, and exposing the p-GaN layer 44 of the monochromatic LED epitaxial structure in the middle at the remaining positions.

[0065] If only photoresist is used, its thickness has engineering limits, and the etching selectivity between photoresist and GaN is insufficient, so the photoresist is completely etched before the target depth is reached. In step S33, a combination of a hard mask and a soft mask is used to ensure etching completeness. After this step is completed, as shown in the third image in Figure 3, the first predetermined sub-pixel area forms a step with the remaining positions. Based on the same principle, multiple steps can be formed.

[0066] S34: Depositing silicon dioxide on the surface of the epitaxial wafer to form a second hard mask.

[0067] S35: Photolithographically patterning a second soft mask on the second hard mask, where the second soft mask covers the first preset sub-pixel region and the second preset sub-pixel region.

[0068] S36: Etching until the second hard mask is completely removed to expose the highest p-GaN layer 44 of the monochromatic LED epitaxial structure in the first preset sub-pixel area, expose the p-GaN layer 44 of the monochromatic LED epitaxial structure located in the middle in the second preset sub-pixel area, and expose the p-GaN layer 44 of the bottom monochromatic LED epitaxial structure in the remaining positions.

[0069] After this step is completed, as shown in the fourth picture in the order of arrows in FIG3 , the first preset sub-pixel area and the second preset sub-pixel area form a first step, and the second preset sub-pixel area and the remaining position form a second step.

[0070] S37: Photolithographically patterning a third soft mask 63 on the surface of the epitaxial wafer. The third soft mask 63 covers the first preset sub-pixel region, the second preset sub-pixel region, the third preset sub-pixel region and four preset driving regions.

[0071] S38: Etching the epitaxial wafer to expose the highest p-GaN layer 44 of the monochromatic LED epitaxial structure in the first predetermined sub-pixel region, expose the middle p-GaN layer 44 of the monochromatic LED epitaxial structure in the second predetermined sub-pixel region, expose the bottom p-GaN layer 44 of the monochromatic LED epitaxial structure in the third predetermined sub-pixel region, expose the top surface of the HEMT epitaxial structure in the predetermined driving region, and leave the remaining positions deep into the substrate 1. The first predetermined sub-pixel region, the second predetermined sub-pixel region, and the third predetermined sub-pixel region can independently become the LED region 4, and the predetermined driving region can become the HEMT region 2.

[0072] After step S38 is completed, as shown in the sixth image in Figure 3 (arrowed in sequence), the LED area 4 remaining in the first predetermined sub-pixel region forms a first step with the LED area 4 remaining in the second predetermined sub-pixel region. The LED area 4 remaining in the second predetermined sub-pixel region forms a second step with the LED area 4 remaining in the third predetermined sub-pixel region. The LED area 4 remaining in the third predetermined sub-pixel region forms a third step with the HEMT area 2 remaining in the predetermined driving region. The HEMT area 2 remaining in the predetermined driving region forms a fourth step with the substrate 1. The fourth u-GaN layer 45 is a significant obstacle to etching the first two steps. The third u-GaN layer 3 is only 150nm-180nm thick, eliminating the need for soft and hard masks in step S37. The photoresist thickness in the third predetermined sub-pixel region is greater than that in the predetermined driving region, allowing step S38 to proceed directly to the substrate 1. In the embodiment of the present application, photoresist is used as a soft mask on silicon dioxide for patterning, and then etching is performed to produce first and second steps. The above process is repeated to produce second and third steps. Then, photoresist is used as a soft mask to etch the mesa and partition the channel, etch the through hole and the patterned pad area, which can overcome the difficulties caused by insufficient etching selectivity to the etching process.

[0073] Unlike photoresist, silicon dioxide cannot be easily separated from gallium nitride by chemical methods. When the thickness of the fourth u-GaN layer 45 is 500nm-600nm, the thickness of the hard mask is specifically set to 500nm-700nm, and the thickness of the soft mask is set to 100nm. This is beneficial for not penetrating the p-GaN layer 44 on the step when the silicon dioxide is completely etched (taking the three monochromatic LED epitaxial structures above the HEMT epitaxial structure that emit blue, green, and red light in sequence as an example, that is, in step S33, the red light p-GaN layer of the first predetermined sub-pixel area will not be penetrated, and in step S36, the red light p-GaN layer of the first predetermined sub-pixel area and the green light p-GaN layer of the second predetermined sub-pixel area will not be penetrated).

[0074] Preferably, in each monochromatic LED epitaxial structure, an electron blocking layer 43 is further grown between the multi-quantum well layer 42 and the p-GaN layer 44, which is beneficial to avoid electron overflow and improve the LED luminous efficiency.

[0075] This invention integrates HEMTs and RGB LEDs on a single substrate at the epitaxial end, interconnecting them through vias and electrode deposition. This approach is highly compatible with the complex pixel circuits of existing technologies and eliminates the impact of parasitic parameters caused by complex packaging and bonding processes. Furthermore, this invention avoids the cumbersome mass transfer and post-transfer inspection processes, contributing to a breakthrough in the industrialization of Micro-LED panels.

[0076] Throughout this specification, references to terms such as "one embodiment," "certain embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" indicate that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0077] 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 HEMT-driven MicroLED integrated backplane, characterized in that: The following steps are involved: growing a HEMT epitaxial structure on a substrate; Three monochromatic LED epitaxial structures are sequentially stacked and grown on the HEMT epitaxial structure to obtain an epitaxial wafer; a third u-GaN layer is grown between the bottom monochromatic LED epitaxial structure and the HEMT epitaxial structure, and a fourth u-GaN layer is grown between adjacent monochromatic LED epitaxial structures, and each monochromatic LED epitaxial structure includes an n-GaN layer, a multi-quantum well layer and a p-GaN layer from bottom to top; Etching to the substrate to partition the epitaxial wafer; The epitaxial wafer after etching comprises: three LED regions each exposing one of the monochromatic LED epitaxial structures and four HEMT regions where the structure above the third u-GaN layer is removed; A passivation layer is deposited, a through hole is etched, and a conductor is deposited, so that the n-GaN layers of three LED regions are connected to one HEMT region, and the remaining three HEMT regions are each connected to the p-GaN layer of one LED region.

2. The method for manufacturing a HEMT-driven MicroLED integrated backplane according to claim 1, characterized in that: The HEMT epitaxial structure includes a buffer layer, a second u-GaN layer and an Al 0.3 Ga 0.7 N layers.

3. The method for manufacturing a HEMT-driven MicroLED integrated backplane according to claim 2, characterized in that: The buffer layer includes a first u-GaN layer and an Al 0.15 Ga 0.85 N layer, the Al 0.15 Ga 0.85 The N layer is 50nm-60nm thick.

4. The method for manufacturing a HEMT-driven MicroLED integrated backplane according to claim 2, characterized in that: The second u-GaN layer and the Al 0.3 Ga 0.7 There is also an AlN layer between the N layers. 0.3 Ga 0.7 The N layer has a thickness of 15nm-25nm, and the AlN layer has a thickness of 0.5nm-8nm.

5. The method for manufacturing a HEMT-driven MicroLED integrated backplane according to claim 1, characterized in that: The thickness of the fourth u-GaN layer is 500nm-600nm.

6. The method for manufacturing a HEMT-driven MicroLED integrated backplane according to any one of claims 1 to 5, characterized in that: The third u-GaN layer has a thickness of 150nm-180nm.

7. The method for manufacturing a HEMT-driven MicroLED integrated backplane according to claim 5, characterized in that: The step of etching to the substrate to partition the epitaxial wafer comprises: Depositing silicon dioxide on the surface of the epitaxial wafer to form a first hard mask; Photolithography a patterned first soft mask on the first hard mask, where the first soft mask covers a first preset sub-pixel area; Etching until the first hard mask is completely removed, so as to expose the highest p-GaN layer of the monochromatic LED epitaxial structure in the first predetermined sub-pixel region, and expose the p-GaN layer of the monochromatic LED epitaxial structure located in the middle at the remaining positions; Depositing silicon dioxide on the surface of the epitaxial wafer to form a second hard mask; Photolithography a patterned second soft mask on the second hard mask, wherein the second soft mask covers the first preset sub-pixel region and the second preset sub-pixel region; Etching until the second hard mask is completely removed, so as to expose the highest p-GaN layer of the monochromatic LED epitaxial structure in the first predetermined sub-pixel region, expose the p-GaN layer of the monochromatic LED epitaxial structure located in the middle in the second predetermined sub-pixel region, and expose the bottom p-GaN layer of the monochromatic LED epitaxial structure in the remaining positions; A patterned third soft mask is photolithographically formed on the surface of the epitaxial wafer, wherein the coverage of the third soft mask is a first preset sub-pixel region, a second preset sub-pixel region, a third preset sub-pixel region and four preset driving regions; The epitaxial wafer is etched to expose the highest p-GaN layer of the monochromatic LED epitaxial structure in the first preset sub-pixel region, expose the middle p-GaN layer of the monochromatic LED epitaxial structure in the second preset sub-pixel region, expose the bottom p-GaN layer of the monochromatic LED epitaxial structure in the third preset sub-pixel region, expose the top surface of the HEMT epitaxial structure in the preset driving region, and the remaining positions are deep to the substrate, so that the first preset sub-pixel region, the second preset sub-pixel region, and the third preset sub-pixel region can independently become the LED region, and the preset driving region can become the HEMT region.

8. The method for manufacturing a HEMT-driven MicroLED integrated backplane according to claim 7, characterized in that: The thickness ratio of the first hard mask to the first soft mask is 5-7:1, and the thickness ratio of the second hard mask to the second soft mask is 5-7:

1.

9. The method for manufacturing a HEMT-driven MicroLED integrated backplane according to claim 1, characterized in that: In each of the monochromatic LED epitaxial structures, an electron blocking layer is also grown between the multi-quantum well layer and the p-GaN layer.

10. A HEMT-driven MicroLED integrated backplane, characterized in that: The method is prepared by any one of claims 1 to 9.

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