2019年6月13日|作者：伤害伤害knoops

We explore the ways that Atomic Layer Deposition (ALD) technology can benefit GaN power devices.

Gallium Nitride (GaN) is a wonderful material for power electronics due to its wide band gap. With the electrification of transport, GaN power devices are becoming more and more important and device cost and efficiencies are critical. For many applications E-mode or normally-off devices are important for fail-safe requirements and gate dielectric layers (such as Al₂O._3.) are vital to obtain more efficient devices in E-mode configurations.

读取下方原子层沉积（ALD）可以帮助实现这些目标和益处GaN设备的5种方式：

• 电影质量
• 适合性
• Control
• Low Damage
• Pre-treatments

1. FILM QUALITY

The thin-film gate dielectric for GaN-based transistors has to be of high quality to result in low leakage and high breakdown voltage. The benefit of ALD and particularly of plasma ALD is that it deposits dense layers resulting in a superior performing device.

Breakdown doesn’t occur until a high voltage which is due to the high quality of the layer and the low level of pin-holes resulting from ALD’s ability to fill voids. Interestingly these properties are obtained at modest temperatures of 200 to 400°C avoiding high temperatures needed for some other techniques.

Figure 1: Cross-sectional schematic of normally-off GaN-on-silicon power device with etched recess and conformal gate dielectric.

White Paper: Atomic Layer Deposition and Atomic Layer Etching for GaN Power Electronics

2. CONFORMALITY

凹陷结构可以对许多定向沉积技术（例如溅射）有挑战性。GaN设备中使用的凹槽几何形状具有相对适度的纵横比，并且对于大多数ALD过程非常容易。

Due to the self-limiting nature of ALD these can be coated conformally with equal thickness throughout the structure. Generally no change in process recipe is needed to maintain conformal deposition for a wide range of device structures and associated aspect ratios.

3.. CONTROL

Both in production and research, thickness and property control are essential. The self-limiting nature of ALD allows for excellent uniformity over large areas, making all devices perform the same. Since the resulting film thickness is based on the number of ALD cycles chosen, excellent reproducibility is obtained as well. Thereby providing the same thickness each run and little variation from machine to machine or day to day.

网络研讨会：您的GAN设备有最好的栅极电介质吗？

由于ALD的逐步性质，也相对容易地将配方或混合材料复制在一起。ALD的这种特性可以轻松遵循未来的材料修改和过程改进的路线图。例如通过上升 -K.HFO等材料₂or going to nitride dielectrics such as AlN.

4.伤害低

与其他半导体相比，GaN表面是电子行业中最流程的敏感之一。幸运的是，远程等离子体ALD流程对GaN造成损坏。优化工艺条件和限制离子能量和磁通允许低缺陷密度界面和薄膜。同时，反应性物种密度和助熔剂足以生长高质量的材料，并且具有可接受的过程的产量。

5. PRE-TREATMENTS

在前面的处理步骤或在空气暴露之后GaN表面可以具有低质量的表面氧化物并且可以含有缺陷和诸如碳的杂质。远程等离子体脉冲和ALD前体脉冲都可用于减少这些。三甲基铝（TMA）是电介质AL的常见ALD前体₂O._3.growth.

有趣的是，TMA实际上可以用作还原剂以除去GaN的一些表面氧化物。已知氢气和氮等离子体也能够减少表面氧化物，并且已知能够去除诸如碳的杂质。

Figure 2: Example of H₂或者n ..₂等离子体预处理和al₂O._3.plasma ALD on GaN to illustrate the effect of pre-treatment and ALD on the surface composition and structure.

我们预计这5种方式只是冰山的尖端，就ALD提供了功率半导体的可能性。将预处理和等离子体ALD与随后的加工相结合，预计将允许进一​​步优化的装置性能。让我们在下面的评论中了解您的问题和想法！