Ultraviolet lithography machine based on gan-based micro-leds, and preparation method therefor
Patent Information
- Application Number
- PCT/CN2025/088264
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-27
- Filing Date
- 2025-04-10
- Publication Date
- 2026-10-01
Smart Images
Figure CN2025088264_01102026_PF_FP_ABST
Abstract
Description
Ultraviolet Lithography Machine Based on GaN-based Micro-LED and Its Fabrication Method Technical Field
[0001] This application belongs to the field of semiconductor lithography technology, specifically, it relates to an ultraviolet lithography machine based on GaN-based Micro-LED and its fabrication method. Background Technology
[0002] With the advancement of Moore's Law, the integration level of integrated circuits is increasing, requiring more complex patterns for photolithography. Furthermore, a single chip needs to integrate more devices, necessitating more photomasks during photolithography. However, the cost of photomasks is a key factor restricting its development. As the feature size of photolithography decreases, the manufacturing cost of photomasks rises significantly, severely limiting the development of photolithography machines. Recently, maskless technology has received widespread attention. Maskless technology is an advanced photolithography technique that eliminates the physical photomasks used in traditional photolithography, instead directly controlling a light beam or electron beam to pattern the wafer surface. This avoids the expensive costs of photomask manufacturing and maintenance, eliminates the need for photomask fabrication, and significantly shortens the cycle from design to production.
[0003] Therefore, researchers are working hard to develop maskless lithography technology. Studies have found that ultraviolet gallium nitride (GaN) micro-LED arrays can achieve rapid pattern changes, thus enabling maskless technology. Since its advent, GaN LED technology has been a core technology in modern lighting and display fields. For its significant contributions, blue GaN LEDs were awarded the Nobel Prize in Physics. With the continuous development of LED technology, micro-LEDs with higher brightness and resolution have attracted widespread interest from researchers. Micro-LEDs are small in size, have high resolution, high brightness, and are easier to integrate into various high-precision devices. GaN Micro-LEDs cover the ultraviolet band, which can well meet the light source requirements of ultraviolet lithography. Furthermore, the fabrication process of GaN Micro-LEDs is mature, and innovative lithography technology based on GaN-based Micro-LEDs in ultraviolet lithography machines is expected to bring new changes to the existing lithography field.
[0004] However, there are very few reports on the design of optical systems for ultraviolet lithography based on GaN-based Micro-LEDs. One possible reason is that Micro-LED light diverges and is difficult to focus. Therefore, it is necessary to design an optical system suitable for Micro-LEDs to balance the various problems of using Micro-LEDs for ultraviolet lithography. Summary of the Invention
[0005] The technical problem addressed in this application is: how to implement an ultraviolet lithography machine based on GaN-based Micro-LEDs.
[0006] This application provides a GaN-based Micro-LED-based ultraviolet lithography machine, the ultraviolet lithography machine comprising:
[0007] An ultraviolet lithography chip, the ultraviolet lithography chip comprising a GaN-based Micro-LED array, wherein each GaN-based Micro-LED is used to independently generate a light beam;
[0008] An optical system, comprising a focusing lens array and a photolithography objective system, wherein the focusing lens array corresponds one-to-one with the GaN-based Micro-LED array, and the photolithography objective system is used to receive and correct the light beam transmitted through the focusing lens array.
[0009] An image display control system, wherein the image display control system is used to control the display pattern of the GaN-based Micro-LED array;
[0010] A motion control system is used to drive the ultraviolet lithography chip to move.
[0011] Optionally, the GaN-based Micro-LED includes a substrate, an N-type semiconductor layer, a multiple quantum well layer, a P-type semiconductor layer, a current diffusion layer, a P-electrode, and an insulating layer stacked sequentially. The substrate also has an N-electrode, and the insulating layer exposes the current diffusion layer, the P-electrode, and the N-electrode.
[0012] Optionally, each of the GaN-based Micro-LEDs shares an N-type semiconductor layer and a substrate, wherein the substrate is a transparent conductive substrate.
[0013] Optionally, the insulating layer covers the sidewalls of the multiple quantum well layer and the P-type semiconductor layer.
[0014] Optionally, the ultraviolet lithography chip further includes a reflector array, which corresponds one-to-one with the GaN-based Micro-LED array, and is used to reflect the light beam generated by the GaN-based Micro-LED array to the optical system.
[0015] Optionally, the reflector array includes:
[0016] A silicon substrate having a hole subarray, wherein the hole subarray corresponds one-to-one with the GaN-based Micro-LED array;
[0017] A reflector array, wherein the reflector array corresponds one-to-one with the hole array, and each reflector in the reflector array is fixedly connected to the corresponding hole.
[0018] Optionally, each focusing lens in the focusing lens array includes a biconvex lens and a plano lens arranged sequentially along the optical path.
[0019] Optionally, the photolithography objective system includes the following components arranged sequentially along the optical path:
[0020] A refractive mirror assembly used to balance aberrations in an optical system;
[0021] A mirror assembly used to balance the field curvature of the optical system;
[0022] Numerical aperture group, which is used to adjust the numerical aperture and telecentricity of the beam.
[0023] Optionally, the motion control system includes:
[0024] A vertical moving device, wherein the ultraviolet lithography chip is mounted on the vertical moving device;
[0025] A horizontal moving device, which is mounted on the vertical moving device.
[0026] This application also provides a method for fabricating an ultraviolet lithography machine for at least the above-mentioned GaN-based Micro-LED.
[0027] This application provides a GaN-based Micro-LED-based ultraviolet lithography machine and its fabrication method, which has the following technical advantages:
[0028] This invention utilizes GaN-based Micro-LED arrays for maskless photolithography, overcoming the limitations of traditional photolithography processes that require masks. This improves the convenience and operability of the photolithography process, enabling real-time image rendering and photolithography. The optical system reduces the divergence of ultraviolet Micro-LED light, ensuring photolithography quality and precision. It also allows for precise control of LED position and exposure patterns to meet complex photolithography requirements. Furthermore, by setting up a reflector array to make the light emission angle of the Micro-LEDs more perpendicular, crosstalk between device arrays can be reduced, thereby improving luminous intensity and photolithography accuracy. Attached Figure Description
[0029] Figure 1 is an overall schematic diagram of a GaN-based Micro-LED ultraviolet lithography machine according to one or more embodiments;
[0030] Figure 2 is a schematic diagram of a GaN-based Micro-LED array according to one or more embodiments;
[0031] Figure 3 is a cross-sectional schematic diagram of a GaN-based Micro-LED according to one or more embodiments;
[0032] Figure 4 is a schematic diagram of the assembly of a GaN-based Micro-LED array and a reflector array according to one or more embodiments;
[0033] Figure 5 is another assembly schematic diagram of a GaN-based Micro-LED array and a reflector array according to one or more embodiments;
[0034] Figure 6 is a schematic diagram of the optical path of a focusing lens array according to one or more embodiments;
[0035] Figure 7 is a schematic diagram of a photolithography objective system according to one or more embodiments;
[0036] Figure 8 is a schematic diagram of the assembly of an ultraviolet lithography chip and a motion control system according to one or more embodiments. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0038] Before describing the various embodiments of this application in detail, the technical concept of this application is first briefly described: In current maskless lithography technology, Micro-LED light is difficult to focus due to its divergence, and therefore it is rarely used in ultraviolet lithography. To address this, this application provides a GaN-based Micro-LED-based ultraviolet lithography machine and its fabrication method. An image display control system controls a GaN-based Micro-LED array to generate a predetermined display pattern, and a motion control system drives the GaN-based Micro-LED array to a predetermined position, allowing the light beam to illuminate the exposure area. An optical system focuses and corrects the light beam, reducing Micro-LED light divergence and ensuring lithography quality and precision. The specific principles of the GaN-based Micro-LED-based ultraviolet lithography machine and its fabrication method of this application are described below with reference to more embodiments.
[0039] Specifically, as shown in Figures 1, 2, and 3, the ultraviolet lithography machine based on GaN-based Micro-LEDs in this embodiment includes an ultraviolet lithography chip 10, an optical system 20, an image display control system 30, and a motion control system 40. The ultraviolet lithography chip 10 includes a GaN-based Micro-LED array, with each GaN-based Micro-LED independently generating a light beam. The optical system 20 includes a focusing lens array 21 and a lithography objective lens system 22. The focusing lens array 21 corresponds one-to-one with the GaN-based Micro-LED array. The lithography objective lens system 22 receives and corrects the light beam transmitted through the focusing lens array 21. The image display control system 30 controls the display pattern of the GaN-based Micro-LED array. The motion control system 40 drives the ultraviolet lithography chip 10 to move. The number of lithography objective lens systems 22 is one, meaning that each focusing lens array 21 is corrected by the same lithography objective lens system 22.
[0040] In one or more embodiments, each GaN-based Micro-LED in the GaN-based Micro-LED array 11 includes a substrate 111, an N-type semiconductor layer 112, a multiple quantum well layer 113, a P-type semiconductor layer 114, a current diffusion layer 115, a P-electrode 116, and an insulating layer 117 stacked sequentially. The substrate 111 also has an N-electrode 118, and the insulating layer 117 exposes the current diffusion layer 115, the P-electrode 116, and the N-electrode 118. The insulating layer 117 covers the sidewalls of the multiple quantum well layer 113 and the P-type semiconductor layer 114 to prevent leakage current from the sides, which could cause a short circuit. Exemplarily, each GaN-based Micro-LED shares the N-type semiconductor layer 112 and the substrate 111, and the substrate 111 is a transparent conductive substrate. Exemplarily, a buffer layer 119 may also be disposed between the substrate 111 and the N-type semiconductor layer 112.
[0041] In one or more embodiments, as shown in Figures 4 and 5, the ultraviolet lithography chip 10 further includes a reflector array 12, which corresponds one-to-one with the GaN-based Micro-LED array 11. The reflector array 12 is used to reflect the light beam generated by the GaN-based Micro-LED array 11 to the optical system 20.
[0042] For example, the reflector array 12 includes a silicon substrate 121 and a reflector sub-array 122. The silicon substrate 121 has a hole sub-array, which corresponds one-to-one with the GaN-based Micro-LED array 11. The reflector array 122 corresponds one-to-one with the hole sub-array, and each reflector in the reflector array 122 is fixedly connected to the corresponding hole. That is, the hole exposes the GaN-based Micro-LED. The light beam generated by the GaN-based Micro-LED passes through the hole and is reflected by the reflector, which can make the light emission angle of the Micro-LED tend to be vertical, thereby reducing the light emission crosstalk between device arrays and improving the light emission intensity and photolithography accuracy.
[0043] In one embodiment, the reflector array 12 can be mounted on the front side of the GaN-based Micro-LED array 11, as shown in Figure 4. Each GaN-based Micro-LED is located within its respective reflector. The light beam generated by the GaN-based Micro-LED is reflected by the reflector and exits from the back side of the GaN-based Micro-LED array 11. In another embodiment, the reflector array 12 can be mounted on the back side of the GaN-based Micro-LED array 11, as shown in Figure 5. Part of the light beam generated by the GaN-based Micro-LED (mainly the divergent beam) is reflected by the reflector, so that all the light beams of the GaN-based Micro-LED exit from the front side.
[0044] In one or more embodiments, as shown in FIG6, each focusing lens of the focusing lens array 21 includes a biconvex lens 211 and a plano-convex lens 212 arranged sequentially along the optical path. Each focusing lens is aligned with a GaN-based Micro-LED to achieve beam focusing. The mechanical aperture of each lens is tens of micrometers, slightly larger than the diameter of the fabricated Micro-LED.
[0045] In one or more embodiments, as shown in FIG7, the lithography objective system 22 is a coaxial objective system. The lithography objective system 22 includes a refractive mirror group 221, a reflective mirror group 222, and a numerical aperture group 223 arranged sequentially along the optical path. The refractive mirror group 221 is used to balance the aberrations of the optical system, the reflective mirror group 222 is used to balance the field curvature of the optical system, and the numerical aperture group 223 is used to adjust the numerical aperture and telecentricity of the beam. For example, the lithography objective system 22 includes a total of 25 elements, with the largest optical element having a mechanical aperture of 220 mm, the smallest optical element having a mechanical aperture of 60 mm, the optical element with the largest radius of curvature being 4000 mm, and the smallest radius of curvature being 50 mm. The assembled optical system mainly includes the refractive mirror group 221, the reflective mirror group 222, and the numerical aperture group 223. The refractive mirror group 221 has the function of balancing system aberrations, the reflective mirror group 222 is used to balance the field curvature generated by the optical system, and the numerical aperture group 223 can be used to ensure a large numerical aperture and a small telecentricity. The final optical system specifications are as follows: wavefront aberration RMS value less than 7.40 nm, calibration F-tanθ distortion less than 6.00 nm, magnification of -0.25, conjugate distance of 1000.11 mm, back intercept of 13.20 mm, and telecentricity of less than 4.6 mrad.
[0046] In one specific embodiment, as shown in FIG8, the motion control system 40 includes a vertical moving device 41 and a horizontal moving device 42. The ultraviolet lithography chip 10 is mounted on the vertical moving device 42, and the horizontal moving device 41 is mounted on the vertical moving device 42. When the workpiece to be exposed changes, the vertical and horizontal positions are adjusted by the motion control system 40 so that the light emitted by the ultraviolet lithography chip 10 can be accurately placed on the workpiece 200 to be exposed after being processed by the optical system.
[0047] For example, the image display control system 30 controls the exposure pattern required for the specific exposure process. Each GaN-based Micro-LED can be individually driven and lit through the image display control system to produce a precise exposure pattern to meet complex photolithography requirements. The image display control system 30 controls the driving circuit through a computer and graphics control software. The chip reads the signals transmitted in the circuit according to its address and confirms whether the LED is lit by identifying whether the electrical signal is at a high or low level. The control process of the image display control system 30 is well-known in the art and will not be described in detail here.
[0048] The above describes the overall structure of the ultraviolet lithography machine based on GaN-based Micro-LED. The following describes its fabrication method with specific examples.
[0049] The first step is the fabrication of the ultraviolet lithography chip, which can be divided into two parts: the fabrication of the GaN-based Micro-LED array and the reflector array.
[0050] In one embodiment, the fabrication method of a GaN-based Micro-LED array is as follows: First, a silicon substrate is prepared and placed in a container filled with acetone and isopropanol. The substrate is ultrasonically cleaned for 5 minutes each, and then placed in a molecular beam epitaxy growth chamber. The Si(111) substrate is preheated to 900°C for several tens of minutes to remove native oxides. Then, a GaN-based Micro-LED device is epitaxially grown. Specifically, the following steps are included:
[0051] In the first step, silicon tetrachloride is decomposed at high temperature in MBE to provide a silicon source. (Al,Ga)N is grown at an Al / Ga flux ratio of 6:4 for 90 minutes to obtain Si-doped n-AlGaN, thus completing the preparation of the N-type semiconductor layer.
[0052] The second step involves growing an Al,Ga)N multiple quantum well layer in the MBE at an Al / Ga flux ratio of 4.5:5.5 for 100 minutes.
[0053] The third step involves introducing a certain amount of Mg and growing (Al,Ga)N at an Al / Ga flux ratio of 6:4 for 90 minutes to obtain Mg-doped p-AlGaN, thus completing the preparation of the P-type semiconductor layer.
[0054] The fourth step involves depositing a layer of Al metal material onto the surface by vapor deposition, thus completing the preparation of the current diffusion layer.
[0055] The fifth step involves depositing Ti / Au and Ni / Au electrode materials onto the P-type and N-type semiconductor layers of the device, respectively, using photoresist as a mask. The photoresist is then removed using a stripping solution, and excess metal material is removed. The P-electrode and N-electrode fabrication is now complete.
[0056] In the sixth step, a 100 nm thick SiO2 layer was deposited at a growth temperature of 80 °C. The deposited SiO2 layer was then patterned and etched to expose the P-electrode, N-electrode, and current diffusion layer, at which point the fabrication of the insulating layer was complete.
[0057] The seventh step is to peel the device off from the silicon substrate and transfer it onto a transparent substrate. This completes the fabrication of the GaN-based Micro-LED device.
[0058] In another embodiment, the fabrication method of the GaN-based Micro-LED array is as follows: First, a silicon substrate is prepared and placed in a container containing acetone and isopropanol. The substrate is ultrasonically cleaned for 5 minutes each, and then placed in a molecular beam epitaxy growth chamber. The substrate is preheated to 900°C for several tens of minutes to remove native oxides. Then, a truncated conical GaN-based Micro-LED device is epitaxially grown.
[0059] Specifically, the steps include the following:
[0060] In the first step, silicon tetrachloride is decomposed at high temperature in MBE to provide a silicon source. (Al,Ga)N is grown at an Al / Ga flux ratio of 6:4 for 90 minutes to obtain Si-doped n-AlGaN, and the N-type semiconductor layer is prepared.
[0061] The second step involves growing an Al,Ga N-type quantum well layer in the MBE at an Al / Ga flux ratio of 4.5:5.5 for 100 minutes.
[0062] The third step involves introducing a certain amount of Mg and growing (Al,Ga)N at an Al / Ga flux ratio of 6:4 for 90 minutes to obtain Mg-doped p-AlGaN, thus completing the preparation of the P-type semiconductor layer.
[0063] The fourth step involves depositing Ti / Au and Ni / Au electrode materials onto the P-type and N-type semiconductor layers of the device, respectively, using photoresist as a mask. The photoresist is then removed using a stripping solution, and excess metal material is removed, thus completing the electrode fabrication.
[0064] The fifth step involves fabricating the device into a truncated cone shape using photolithography and dry etching, followed by high-temperature annealing for 2 minutes.
[0065] In the sixth step, a 100 nm thick SiO2 layer was deposited at a growth temperature of 80 °C. The deposited SiO2 layer was then patterned and etched to expose the P-electrode, N-electrode, and current diffusion layer, at which point the fabrication of the insulating layer was completed.
[0066] The seventh step is to peel the device off from the silicon substrate and transfer it onto a transparent substrate. This completes the fabrication of the GaN-based Micro-LED device.
[0067] Next, the reflector array is fabricated and assembled, which includes the following steps:
[0068] The first step is to prepare a silicon substrate, place the silicon substrate in a container containing acetone and isopropanol, and ultrasonically clean it for 5 minutes each. Then place it in a molecular beam epitaxy chamber and preheat it to 900°C for several tens of minutes to remove natural oxides.
[0069] The second step is to confirm the size and position of the GaN-based Micro-LED array through characterization methods, and to form a concave hole array on the Si substrate through etching process that matches the size and position of the GaN-based Micro-LED array.
[0070] The third step is to deposit Al in a concave hole array to form a reflector using a vapor deposition process.
[0071] The fourth step is to cut the reflector array and use a flip-chip bonding machine to combine the cut reflector array with the GaN-based Micro-LED array;
[0072] The fifth step is to install wires and connect the external driving circuit. The ultraviolet lithography chip of GaN-based Micro-LED is now fabricated. The chip assembly process is shown in Figure 5.
[0073] Furthermore, the prepared ultraviolet lithography chip is assembled and connected with the focusing lens array 21, the lithography objective lens system 22, the horizontal moving device, the vertical moving device, and the image display control system to form an ultraviolet lithography machine based on GaN-based Micro-LED.
[0074] The specific embodiments of this application have been described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that modifications and improvements can be made to these embodiments without departing from the principles and spirit of this application as defined by the claims and their equivalents, and such modifications and improvements should also be within the protection scope of this application.
Claims
1. A GaN-based Micro-LED based UV lithography machine, wherein, The ultraviolet lithography machine includes: An ultraviolet lithography chip, the ultraviolet lithography chip comprising a GaN-based Micro-LED array, wherein each GaN-based Micro-LED is used to independently generate a light beam; An optical system, comprising a focusing lens array and a photolithography objective system, wherein the focusing lens array corresponds one-to-one with the GaN-based Micro-LED array, and the photolithography objective system is used to receive and correct the light beam transmitted through the focusing lens array. An image display control system, wherein the image display control system is used to control the display pattern of the GaN-based Micro-LED array; A motion control system is used to drive the ultraviolet lithography chip to move.
2. The GaN-based Micro-LED based UV lithography machine of claim 1, wherein, The GaN-based Micro-LED comprises a substrate, an N-type semiconductor layer, a multiple quantum well layer, a P-type semiconductor layer, a current diffusion layer, a P-electrode, and an insulating layer stacked sequentially. The substrate also has an N-electrode, and the insulating layer exposes the current diffusion layer, the P-electrode, and the N-electrode.
3. The GaN-based Micro-LED based UV lithography machine of claim 2, wherein, Each of the GaN-based Micro-LEDs shares an N-type semiconductor layer and a substrate, wherein the substrate is a transparent conductive substrate.
4. The GaN-based Micro-LED based UV lithography machine of claim 2, wherein, The insulating layer covers the sidewalls of the multiple quantum well layer and the P-type semiconductor layer.
5. The GaN-based Micro-LED based UV lithography machine of claim 1, wherein, The ultraviolet lithography chip also includes a reflector array, which corresponds one-to-one with the GaN-based Micro-LED array. The reflector array is used to reflect the light beam generated by the GaN-based Micro-LED array to the optical system.
6. The GaN-based Micro-LED based UV lithography machine of claim 5, wherein, The reflector array includes: A silicon substrate having a hole subarray, wherein the hole subarray corresponds one-to-one with the GaN-based Micro-LED array; A reflector array, wherein the reflector array corresponds one-to-one with the hole array, and each reflector in the reflector array is fixedly connected to the corresponding hole.
7. The GaN-based Micro-LED based UV lithography machine of claim 1, wherein, Each focusing lens in the focusing lens array includes a biconvex lens and a plano lens arranged sequentially along the optical path.
8. The GaN-based Micro-LED based UV lithography machine of claim 7, wherein, The photolithography objective lens system comprises the following components arranged sequentially along the optical path: A refractive mirror assembly used to balance aberrations in an optical system; A mirror assembly used to balance the field curvature of the optical system; Numerical aperture group, which is used to adjust the numerical aperture and telecentricity of the beam.
9. The GaN-based Micro-LED based UV lithography machine of claim 1, wherein, The motion control system includes: A vertical moving device, wherein the ultraviolet lithography chip is mounted on the vertical moving device; A horizontal moving device, which is mounted on the vertical moving device.
10. A method for fabricating an ultraviolet lithography machine based on GaN-based Micro-LEDs as described in claim 1.