第三代半导体外延生长缺陷的光学原位监测方法研究

The gallium nitride (GaN) and silicon carbide (SiC) based third generation semiconductors are featured with high superior field strength, high thermal conductivity, high electron saturation rate and high radiation resistance. Epitaxial growth is used for preparation of these materials. In-situ monitoring system is comparable to "eyes" of epitaxial equipments. At present, there is a lack of effective real-time monitoring instruments, especially for epitaxial growth defects. This project presents a real-time in-situ monitoring method for defects under variable temperature conditions from 400°C to 1200°C. The theoretical relationship between photoluminescence and epitaxial growth defects will be proposed. And the algorithm of real-time acquisition and analysis of weak photoluminescence spectral signals in complex environment will be studied. Then the in-situ mornitoring system will be set up. Besides, system calibration and measurement error compensation methods will be studied. And then it will be integrated with the original multi-parameter monitoring system. Finally, it will be applied to the epitaxial growth process of GaN-based solid-state light-emitting devices and power devices. This is expected to promote the yield of the third generation semiconductor devices.

以氮化镓(GaN)、碳化硅(SiC)等为代表的第三代半导体具有高击穿场强、高热导率、高电子饱和率、高抗辐射能力等优越性能。通常采用薄膜外延生长技术来制备。多参数原位监测系统好比外延生长设备的"眼睛"，目前，特别对于外延生长缺陷缺乏有效的实时监测仪器。本项目提出基于实时光致发光光谱原位监测方法，实现在复杂变温(400℃~1200℃)的条件下对外延生长缺陷的检测。拟建立光致发光光谱与外延生长缺陷的理论关系，研究微弱光致发光光谱信号实时采集与分析算法，并搭建系统实现外延膜层缺陷和杂质水平的检测。然后深入研究系统校准及误差补偿技术，实现变温光致发光光谱原位监测系统与现有多参数监测系统的集成。最后将该技术应用于GaN基固态发光器件和功率器件等外延生长工艺，促进第三代半导体器件外延良品率的提升。

目前，对于第三代半导体外延片/芯片的生长缺陷缺乏有效的实时检测仪器。项目成员建立了一种针对第三代半导体缺陷的光致发光实时检测方法：研究了光致发光光谱与外延片/芯片缺陷的理论关系，发展了复杂环境中微弱信号实时采集与分析的算法；搭建了多波长光致发光缺陷实时检测系统，验证检测方法及系统设计的可行性；进一步地，优化光致发光缺陷实时检测系统方案，优化设计显微光路获得高信噪比的光致发光图像；结合杂散光抑制技术、低噪声检测电路设计技术、高速信号处理与特征提取技术、系统校准与误差补偿技术，实现系统的优化设计与定标。最后，项目成员对LED外延片和尺寸较大的Micro LED芯片样品进行了初步研究，通过样品的光致发光图像和光谱信息实现对芯片样品的划痕、缺角和裂缝的缺陷进行识别，并判断外延片样品的发光缺陷、发光波长偏移等，促进第三代半导体器件良品率的提升。