基于静电吸附的LED晶粒转移技术

Mini LED、Micro LED等新型显示技术以其高亮度、高清晰度、低能耗等优势，正逐渐取代LCD、OLED等传统显示技术。在新型LED屏幕生产过程中，需要将小尺寸的LED晶粒大批量地转移到电路基板上，目前这一工艺尚无兼顾成本、效率、质量等方面的成熟市场化方案。本文结合静电吸附结构简单、易于微缩、控制简单等特点，提出一种基于静电吸附的LED晶粒批量转移技术，通过调控吸附电极的静电力，实现LED晶粒的批量与选择性吸附，并通过检测吸附过程的电流变化感知LED晶粒的吸附释放状态。

本文分析静电吸附在微小LED晶粒转移中的力分布、响应时间、击穿电压、可靠性等特点，从静电吸附的机理出发分析影响静电吸附力的因素。设计单电极、共面平行双电极及三电极吸附构型，利用COMSOL静电模块仿真计算电极构型对LED晶粒的吸附力并确定是否满足抓取LED晶粒的最小吸附力。对共面平行电极构型进行不同电极参数下的静电吸附力仿真分析，为电极优化提供参考。通过分析吸附LED晶粒过程中吸附电极的电容及电荷变化，提出基于电流反馈检测LED晶粒吸附状态的方法。

对静电吸附电极的制作工艺以及微缩化阵列化连接方式进行研究，并优化造成静电击穿的因素。设计静电吸附力测试系统进行不同参数下静电吸附力的测试，得到电极间隙越窄、介电层厚度越薄、电压越高静电吸附力越大的结论，并探究吸附电极表面粗糙度对静电吸附力的影响。设计静电吸附响应时间测试系统，用于测试静电吸附力产生及衰减的响应时间，测得静电吸附力响应时间为5.24ms，衰减时间为0.21ms。对于静电吸附力的稳定性以及吸附电极的击穿电压等可靠性进行测试，100组相同条件下吸附力测试离散系数为2.83%。综合以上各种因素，设计转移平台，利用静电吸附单元阵列对10×10的LED晶粒进行选择性图案转移。

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