正在开发新的GAN电力电子设备用于电力转换和交付。在电动运输（例如电动和混合动力汽车（EV和HEV））中，这些设备变得越来越重要，设备成本和效率对于它们的成功至关重要。GAN的高移动性和故障电压使其成为电源设备的理想材料。特别是，发生在Algan/GAN界面处的2D电子气体可提供非常有效的设备。However, the AlGaN layer requires a negative voltage on the gate to turn off. Such “D-mode” or “normally-on” devices do not meet fail-safe design criteria and therefore there is a strong drive to develop “E-mode” or “normally-off” devices. There are several strategies to create such devices and using recess etching of the AlGaN barrier is a prominent one. Furthermore, gate dielectric layers are desired to limit leakage currents.
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图1。电子模式Gan-on-Silicon Power设备。使用嵌入式蚀刻和栅极介电可以允许使用低泄漏和低功率损耗的正常设备。需要原子量表处理技术（例如ALD和ALE）来控制蚀刻和沉积，并且对敏感界面的损害较低。
A cross-sectional schematic of an E-mode GaN-on-silicon power device is shown in Fig. 1. Note that various designs have various depths of recess etches, ranging from almost no recess to complete removal of the AlGaN barrier layers and even partly the GaN channel. In all of these cases, a high-quality dielectric and high-quality interface with the dielectric are desired to allow for an E-mode device with low leakage and low power losses. In contrast to other semiconductors, the GaN surface is one of the most process-sensitive in the electronic industry 1. Therefore, precise control of the applied processes is needed. Several challenges exist around recess etching and gate dielectric deposition which will be discussed further. For the recess etch, the AlGaN layer needs to be etched down to the underlying GaN. This AlGaN layer is thin, typically 20-30 nm and there is no inherent selectivity to GaN for a classic etch process. Therefore, an extremely uniform, reproducible, and slow etch rate is essential to have a satisfactory etch result across a complete 200 mm wafer. For the dielectric deposition, a thin conformal dielectric must be deposited in the recess structure. For both the etch and the deposition the processes should have low damage and result in high-quality interfaces with low defect levels. Plasma processes are desirable here to allow for directional etching and to help deposit high-quality layers at modest thermal budget. The reactive species in the plasma such as radicals and ions mean that etching is facile and high-quality material can be deposited as well. However, it also means that the energy and fluxes of the species must be carefully managed to limit damage to the device.
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This information has been sourced, reviewed and adapted from materials provided by Oxford Instruments Plasma Technology.
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