Thermoreflectance Microscope (TRM)

热反射显微镜 (TRM)

• 批准号: 525779412
• 金额: --
• 依托单位: Technische Universität Chemnitz
• 依托单位国家: 德国
• 项目类别: Major Research Instrumentation
• 财政年份: 2023
• 资助国家: 德国
• 起止时间: 2022-12-31 至 无数据
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/525779412?language=en
• 关键词: Thermoreflectance; Microscope; TRM

To better understand the physical processes in semiconductor power devices, especially in overload conditions (short circuit, overcurrent), it is necessary to measure the chip temperature with high spatial and temporal resolution. The measurement should be non-invasive to avoid artificially introduced inhomogeneities. In contrast to infrared-based methods, thermo-reflectance microscopy can meet these requirements and measure the temperature on the front-side metallization of the chips without prior preparation. Current filaments with high current densities in bipolar devices such as IGBTs, which occur during turn-off or short-circuit, can be visualized with this method since the filaments lead to thermal "footprints" on the chip. Until now, these filaments have only been visible in semiconductor simulators because they have very small spatial dimensions in the micrometer range and stay in place only for a few 10 to 100 nanoseconds before extinguishing. For the first time, these phenomena can be observed in real structures and possible weak spots on the chip can be localized, which has already been verified in test measurements on IGBTs under short-circuit condition. This research will contribute to further optimization and robustness improvement of the power semiconductors. Geometric weaknesses leading to current crowding can be avoided in the design. The physical understanding of filament movement can be analyzed on real chips for the first time. In addition to bipolar devices, unipolar devices such as GaN HEMTs or SiC MOSFETs can also be investigated. For SiC MOSFETs, after the growth of stacking faults, the thermal imprint shall be investigated non-invasively with short pulses. Until now, complex preparations for electroluminescence or photoluminescence measurements are necessary. Temperature inhomogeneities on SiC chips in short-circuit or avalanche condition, which can arise at (crystal) defects or at the transition to edge regions, are to be investigated. For this purpose, the thermo-reflectance microscope is synchronized with dynamic test benches in our laboratories. Several measurements can also be superimposed to improve the measurement quality (lock-in). GaN devices will be measured directly to investigate trapping effects in gate regions. So far, only electrical measurements of the dynamic RDSON have been performed on our test benches for this purpose. For special power-cycling tests, which are operated with very short on-times or using heating via switching losses, the temperature distribution at the bond feet during the short heating phases is to be investigated and gives us an improved picture of possible inhomogeneities. So far, this can only be assumed via the final failure analysis and thermo-mechanical simulations. In the field of classical failure analysis, we expect a significant improvement in the localization of small leakage currents.

为了更好地了解半导体功率器件中的物理过程，特别是在过载条件下（短路、过流），有必要对芯片温度进行高时空分辨率的测量。测量应是非侵入性的，以避免人为引入的不均匀性。与基于红外的方法相比，热反射显微镜可以满足这些要求，无需事先准备即可测量芯片正面金属化的温度。在双极器件（如igbt）中，在关断或短路期间发生的具有高电流密度的电流细丝可以用这种方法可视化，因为细丝会导致芯片上的热“足迹”。到目前为止，这些细丝只在半导体模拟器中可见，因为它们在微米范围内的空间尺寸非常小，并且在熄灭前只能在原地停留10到100纳秒。这些现象首次可以在实际结构中观察到，并且可以定位芯片上可能存在的薄弱点，这已经在短路条件下的igbt测试测量中得到了验证。该研究将有助于进一步优化和提高功率半导体的鲁棒性。在设计中可以避免导致电流拥挤的几何缺陷。第一次可以在真实芯片上分析灯丝运动的物理理解。除了双极器件，单极器件如GaN hemt或SiC mosfet也可以研究。对于SiC mosfet，在层错生长后，需要用短脉冲非侵入性地研究热压印。到目前为止，需要复杂的电致发光或光致发光测量准备。研究了SiC芯片在短路或雪崩条件下的温度不均匀性，这种温度不均匀性可能出现在（晶体）缺陷处或向边缘区域过渡处。为此，热反射显微镜与我们实验室的动态试验台同步。几个测量也可以叠加，以提高测量质量（锁定）。GaN器件将直接测量以研究栅极区域的捕获效应。到目前为止，仅在我们的测试台上进行了动态RDSON的电气测量。对于特殊的功率循环测试，即在很短的接通时间内运行或通过开关损耗加热，需要研究短加热阶段键脚处的温度分布，从而更好地了解可能存在的不均匀性。到目前为止，这只能通过最终的失效分析和热力学模拟来假设。在经典失效分析领域，我们期望在小泄漏电流的局部化方面有显著的改进。