基于傳統(tǒng)色轉(zhuǎn)換LED器件，色域限制在約90%NTSC以內(nèi)，顯示效果已經(jīng)難以進一步地突破。采用量子點等新型發(fā)光材料所制成的LED器件，通過色轉(zhuǎn)換過程可實現(xiàn)紅、藍及綠波段較窄的發(fā)射半波寬（＜20 nm），色域可以超過120%NTSC，被視為下一代最有潛力的顯示技術(shù)之 一。但是，目前量子點LED器件仍缺乏有效封裝設(shè)計，在色轉(zhuǎn)換結(jié)構(gòu)及芯片集成方面仍普遍沿用傳統(tǒng)封裝結(jié)構(gòu)，因此，限制了器件發(fā)光效率與穩(wěn)定性的提升。
based on traditional color conversion LED devices, the color gamut is limited to around 90% NTSC, and the display effect has been difficult to further breakthrough. LED devices made of new luminescent materials such as quantum dots can achieve narrower emission half widths (less than 20 nm) in the red, blue, and green wavelength bands through the color conversion process. The color gamut can exceed 120% NTSC, which is considered one of the most promising next-generation display technologies. However, currently quantum dot LED devices still lack effective packaging design, and the color conversion structure and chip integration are still commonly used in traditional packaging structures, which limits the improvement of device emission efficiency and stability.
2023年7月5日，上海芯元基半導體采用化學剝離GaN技術(shù)，通過特殊設(shè)計的光學反射層及量子點色轉(zhuǎn)換技術(shù)，實現(xiàn)了高良率、高效純紅光倒裝結(jié)構(gòu)和正裝結(jié)構(gòu)的量子點MiniLED芯片。該項重大技術(shù)的突破將有效降低紅光芯片的成本，提高產(chǎn)品的性價比，或?qū)⑷嫣崴倭孔狱c顯示技術(shù)的商業(yè)化進程。
The breakthrough in technology by ChipFoundation Semiconductor on July 5, 2023,3, involves the use of chemical lift-off GaN from sapphire technique, along with a specially designed optical reflector and quantum dot color conversion technology. This breakthrough enables the production of high-efficiency, high-purity red light flip-chip quantum dot MiniLED chips and horizontal structure quantum dot MiniLED chips. The significant advancement is expected to effectively reduce the cost of red light chips, improve product cost-effectiveness, and potentially accelerate the commercialization process of quantum dot display technology.
Figure 1: Structural schematic diagram
倒裝結(jié)構(gòu)量子點芯片技術(shù)方面，芯元基將剝離后的GaN芯片的出光面，用量子點膠水貼合到已經(jīng)加工好的特殊光學反射層基板上，該光學反射層，對激發(fā)光源的波長具有高反射率，對量子點發(fā)光的波段具有非常高的透光率，以此來實現(xiàn)紅光量子點更好激發(fā)，實現(xiàn)了紅光量子點厚度小于１微米的情況下，量子點完全激發(fā)后，紅光芯片無漏藍光等現(xiàn)象。量子點芯片加工過程中，我們采用標準的半導體制程，結(jié)合光罩對準方法，在像素的側(cè)壁做有高密度的介質(zhì)層，實現(xiàn)量子點的完全密封，解決量子點在可靠度方面的顧慮。
In the flip-chip quantum dot chip technology, the chip substrate will lift off. ChipFoundation Semiconductor utilizes quantum dot glue to attach the light-emitting surface of the GaN chip to a pre-fabricated special optical reflection layer substrate. This optical reflector has a high reflectivity for the excitation wavelength of the light source and a very high transmittance for the emission wavelength of the quantum dot, thus achieving efficient excitation of the red light quantum dots. By doing so, the quantum dot thickness can be reduced to less than 1 micrometer while ensuring that the red light chip is fully excited without leakage of blue light or other phenomena. During the processing of the quantum dot chips, a standard semiconductor process is used, combined with mask alignment methods, to create a high-density dielectric layer on the sidewall of the pixel, achieving complete sealing of the quantum dots and addressing concerns about their reliability.
Figure 2: Optical Reflection Layer Design
產(chǎn)品的特性曲線如下：（芯片尺寸：2*4mil/50*100um）
特性曲線：
Forward Voltage Vs Forward current
Forward current Vs Relative Luminous Intensity
Forward current Vs Dominant Wavelength
產(chǎn)品的發(fā)光情況及良率如下表：
表一：發(fā)光測試情況及良率：
后續(xù)，芯元基半導體將以此技術(shù)為基礎(chǔ)，進一步開發(fā)與量子點色轉(zhuǎn)換層相關(guān)顯示器件技術(shù)，以達到未來高分辨率顯示系統(tǒng)的實際需求?；谠摿孔狱c技術(shù)方案，芯元基半導體正在為國際知名機構(gòu)開發(fā)尺寸小于0.2mm*0.2mm的量子點MIP器件。
In the future, ChipFoundation Semiconductor will further develop display device technologies related to quantum dot color conversion layers based on this technology to meet the practical requirements of high-resolution display systems.based on this quantum dot technology scheme, ChipFoundation Semiconductor is currently developing quantum dot MIP(Micro LED in Package) devices with dimensions smaller than 0.2mm*0.2mm for internationally renowned institutions.
芯元基的量子點MIP技術(shù)，在GaN晶圓的每個子像素的側(cè)壁均做有金屬電極結(jié)構(gòu)，這種結(jié)構(gòu)除了有利于像素的共陰極設(shè)計外，也可以更好的解決獨立子像素間的光串擾問題,在RGB量子點模板上（QDCC），采用特定結(jié)構(gòu)設(shè)計的光學反射鏡，實現(xiàn)紅光、綠光的高效激發(fā)。所有的制程均采用標準的晶圓加工工藝，不需要巨量轉(zhuǎn)移工藝，直接將晶圓芯片和QDCC模板鍵合，可更容易降低MIP的產(chǎn)業(yè)成本的同時，實現(xiàn)高可靠性的像素單元。
The ChipFoundation's quantum dot MIP technology has a metal electrode structure on the N-GaN sidewall of each sub pixel of the wafer . In the RGB quantum dot color conversion (QDCC) template, an optically reflective mirror with a specific structural design is used to achieve efficient excitation of red and green light. All processes are carried out using standard wafer fabrication techniques, eliminating the need for massive transfer processes. The wafer chip can be directly bonded to the QDCC template, making it easier to reduce the production cost of MIP while achieving high reliability of the pixel unit.
