Reliability of T‐gate AlGaN/GaN HEMTs
Reliability of T‐gate AlGaN/GaN HEMTs
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T 栅 AlGaN/GaN HEMT 的可靠性
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
M. Micovic
中科院分区：
文献类型：
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作者：
S. Burnham;R. Bowen;P. Willadsen;H. Bracamontes;P. Hashimoto;Ming Hu;D. Wong;Mary Y. Chen;M. Micovic
我们首次报道了短栅长（Lg = 0.15 μm）T栅AlGaN/GaN HEMT的退化机制，并与之前报道的相同栅长GaN场板器件的结果进行了比较。这两种类型的研究设备进行了温度应力测试在空气中。T-栅极器件用15 V的漏极偏置施加应力，而场板器件用30 V的漏极偏置施加应力。一些T-栅极器件还在干燥氮气中施加应力以观察环境的任何影响。与在氮气中受应力的器件相比，在空气中受应力的器件失效更快并且结温更低。对达到失效标准的器械进行的FIB-STEM、EDS和EELS分析显示，在空气中受应力的器械可能由于氧化物形成而更快失效。对于在空气中受应力的T栅极器件，在TEM图像中直接在栅极脚下方观察到氧化物形成。对于在空气中受应力的场板器件，在TEM图像中在栅极的漏极侧上的栅极底脚金属与场板电介质之间的界面处观察到氧化物。对于在干燥氮气中受应力的T栅极器件，在TEM图像中观察到栅极下沉到阻挡层中，而对于场板器件没有观察到或已经报道了栅极下沉。在不同应力偏置条件下对这两种结构进行的基于物理的器件建模表明，与场板器件相比，T型栅极器件的栅极下的电场要高得多，尽管场板器件的漏极偏置要高得多。（© 2011 WILEY-VCH Verlag GmbH & Co. KGaA，魏因海姆）
For the first time, we report on degradation mechanisms of short gate length (Lg = 0.15 µm) T-gate AlGaN/GaN HEMTs, and compare to previously reported findings for GaN field plate devices of the same gate length. Both types of studied devices were subjected to temperature-stress tests in air. T-gate devices were stressed with a drain bias of 15 V, while field plate devices were stressed with a drain bias of 30 V. Some T-gate devices were also stressed in dry nitrogen to observe any impact of the environment. The devices stressed in air failed faster and at a lower junction temperature than the devices stressed in nitrogen. FIB-STEM, EDS and EELS analysis of devices that reached failure criteria revealed that the devices stressed in air may have failed faster due to an oxide formation. For a T-gate device stressed in air, an oxide formation was observed directly underneath the gate foot in a TEM image. For a field plate device stressed in air, an oxide was observed at the interface between the gate foot metal and the field plate dielectric on the drain side of the gate in a TEM image. Gate sinking into the barrier was observed in a TEM image for a T-gate device stressed in dry nitrogen, while no gate sinking was observed or has been reported for field plate devices. Physics-based device modeling of the two structures at the different stress bias conditions reveals that the electric field under the gate is much higher for the T-gate device compared to the field plate device, despite the much higher drain bias for the field plate device. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)