GaN基LED芯片键合工艺研究

发布时间：2018-06-12 10:41

本文选题：薄层金属键合 + Au-Si共晶　；参考：《南京大学》2015年硕士论文

【摘要】：氮化镓(GaN)基发光二极管(LED)是目前固态照明领域的研究焦点。产业界通常采用异质外延生长GaN薄膜,普遍采用蓝宝石(Al2O3)作为衬底外延生长GaN薄膜,但晶格失配(13.4%)严重制约GaN薄膜的质量,影响LED的性能。另外热膨胀系数的差异(25.5%)对大功率LED也有不利的影响。硅(Si)衬底的导热和导电性要优于蓝宝石材料,在氮化镓(GaN)基发光二极管(LED)领域具有良好的应用前景,但Si衬底材料同样具有晶格失配与热膨胀差异的问题。利用晶圆键合技术可以在不影响GaN薄膜质量的前提下实现A1203基GaN薄膜向Si衬底的转移。晶圆键合技术作为晶圆级封装的关键技术,是目前芯片封装领域的研究焦点。晶圆级封装技术可以实现在整片晶圆级别上完成封装与测试,并且能够减小封装后的芯片尺寸,同时大幅降低封装与测试成本,因此成为未来芯片封装的发展方向。在GaN基LED领域,晶圆键合技术同样有关键的应用,利用晶圆键合工艺,可以将蓝宝石衬底的GaN外延层转移至硅衬底上,从而在不改变GaN薄膜质量的同时获得更优秀的导热与导电性,实现高效及大功率GaN基LED芯片制备。本论文选择Au-Si共晶作为晶圆键合手段,完成了Si-Si, Si-GaN晶圆键合,主要工作内容如下：1.在Si衬底上制备Si/Au、Si/Ni/Au、Si/Ti/Au结构多层膜,进行多种条件下的退火实验,研究了不同结构金属层对Au/Si共晶体系中硅扩散的影响,并提出势垒模型来解释扩散阻挡层的失效机制。2.利用Au-Si共晶技术完成了Si-Si、Si-GaN晶圆键合,通过调整键合工艺,添加共晶扩散步骤,实现了较薄金属过渡层条件下的高强度键合。上述研究完成了芯片衬底转移工艺的理论及实验准备,可以为后期的倒装型LED、垂直型LED芯片制备提供实验基础。
[Abstract]:Gallium nitride (gan)-based light emitting diode (LED) is the focus of solid state lighting. Gan thin films are grown by heteroepitaxial growth in industry, and gan films are grown on sapphire Al2O3 substrate. However, lattice mismatch (13.4) seriously restricts the quality of gan films and affects the performance of LED. In addition, the difference in coefficient of thermal expansion of 25. 5) also has a negative impact on high-power LEDs. The thermal conductivity and electrical conductivity of Si / Si substrates are superior to those of sapphire materials and have a good prospect in the field of GaN-based light emitting diodes (LEDs), but Si substrates also have the difference of lattice mismatch and thermal expansion. The wafer bonding technique can realize the transfer of A1203 gan films to Si substrates without affecting the quality of gan films. Wafer bonding technology, as the key technology of wafer level packaging, is the focus of research in chip packaging field. Wafer level packaging technology can achieve packaging and testing at the wafer level, and can reduce the chip size after packaging, and greatly reduce the cost of packaging and testing, so it will become the development direction of chip packaging in the future. Wafer bonding technology also has a key application in GaN-based LED field. Using wafer bonding technology, gan epitaxial layer of sapphire substrate can be transferred to silicon substrate. Thus, better thermal conductivity and conductivity can be obtained without changing the quality of gan films, and high efficiency and high power GaN-based LED chips can be fabricated. In this paper, Au-Si eutectic is selected as wafer bonding method. Si-Si, Si-GaN wafer bonding is accomplished. The main work is as follows: 1. The Si / au / Ni / Ni / Si / Ti / au multilayer films were prepared on Si substrates. Annealing experiments were carried out under various conditions. The effects of different structure metal layers on silicon diffusion in Au/ Si eutectic system were investigated, and a barrier model was proposed to explain the failure mechanism of diffusion barrier layer. The Si Si Si gan wafer bonding was accomplished by Au-Si eutectic technology. By adjusting the bonding process and adding the eutectic diffusion step, the high strength bonding was realized under the condition of thin metal transition layer. The above studies have completed the theoretical and experimental preparation of chip substrate transfer technology, which can provide experimental basis for the fabrication of inverted LED and vertical LED chips.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN312.8

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