利用最佳化的場板設計以提升氮化鎵異質接面場效電晶體之最大崩潰電壓

Optimization of Various Field Plate Design in Enhancing the Maximum Breakdown Voltage of GaN heterojunction Field Effect Transistor

徐志維(Chih-Wei Hsu)

指導教授 ： 吳育任

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201704433

摘要

眾所周知，氮化鎵（GaN）高電子遷移率晶體管（HEMT）是良好的大功率半導體器件，因為它們的極化場而具有高擊穿電壓，高遷移率和大量的二維電子氣。為了在高電壓下操作HEMT，使用場板來提高HEMT的擊穿電壓是必要的。在本文中，我們研究了不同的傾斜或彎曲場板，以研究對通道中峰值電場的減小的影響。施加了具有彎曲側壁（傾斜或彎曲的場板）的SiN鈍化的柵極。通過這種結構，將研究不同電壓的峰值電場以找到優化條件。我們將研究場板的不同配置，以了解場板的幾何如何減小沿著通道的峰值電場。
在我們的研究結果中，在不優化的情況下，不同配置的峰值電場主要位於最高工作電壓下的柵極端向漏極側端點和傾斜場板的端點。凹形結構使得柵極和場板之間的電場平衡更好。另外，目前也受不同傾斜場板厚度的影響。通過使用彎曲場板，可以以更平滑的電場分佈來增加器件的擊穿電壓。而且，彎曲場版可以使擊穿電壓達到500伏特，雖然可能難以製造彎曲的場板。然而，通過控制蝕刻角度和選擇性蝕刻溶劑，對於未來的應用來說仍然是可行的。

關鍵字

場板 ； 場效電晶體

並列摘要

It is well known that gallium nitride (GaN) high-electron-mobility transistors (HEMTs) are good high-power semiconductor devices because they have high breakdown voltage, high mobility, and large amount of 2DEG due to the polarization field. To operate HEMTs in high voltage, using the field plate to enhance the breakdown voltage of the HEMTs is necessary. In this paper, we studied the different slanted or curved field plates to investigate the influence to the reduction of the peak electric field in the channel. Gates deposited on SiN passivation with a curved sidewall (the slanted or curved field plate) were applied. With this structure, the peak electric field with different voltage will be studied to find the optimized condition. We will examine different configurations of the field plates to see how the geometries of the field plate reduce the peak electric field along the channel.
In our investigated results show that , the peak electric fields of different configurations are mainly located at the end point of gate toward the drain side and the end point of the curve field plate at the highest operation voltage. In addition, the current is also affected for different length of gate. By using a curved field plate, it is possible to increase the breakdown voltage of the device with a more smooth distribution of electric field. And the breakdown voltage can be up to 500V in the curve structure. It might be difficult to fabricate a curved field plate. However, by controlling the etching angle and selective etching solvent, it might still be feasible for future applications.

並列關鍵字

field plate ； HFETs

參考文獻

W. Schaff, L. Eastman, R. Dimitrov, L. Wittmer, et al.,

“Piezoeffect and gate current in AlGaN/GaN high electron mobility

simple model for GaAs heterojunction fet gate characteristics,”

IEEE Transactions on Electron Devices, vol. 35, no. 5, pp. 570–

microwave applications,” in Microwave Conference (GeMIC),