PECVD氮化矽閘極介電層之氮化鋁鎵/氮化鎵高電子遷移率電晶體特性

The Characteristics of AlGaN/GaN MIS-HEMT with PECVD-SiN as Gate Dielectric

王惠弘(Hui-Hung Wang)

指導教授 ： 黃智方

國立清華大學/電機資訊學院/電子工程研究所/碩士(2012年)

https://doi.org/10.6843/NTHU.2012.00687

摘要

本篇論文中，利用矽基板上長成氮化鎵/氮化鋁鎵試片製作高電子遷移率電晶體，並以線性元件為主要量測元件，並搭配指叉型元件作電性分析量測，實驗主軸分為兩部分，一種是以三種不同閘極製程在不同磊晶結構上對元件作電性分析，包括蕭基特閘極、金屬-絕緣層-半導體閘極、掘入式金屬-絕緣層-半導體閘極。另一種為相同閘極製程在不同試片上的影響，並比較崩潰表現。
對於不同閘極製程作電性比較，金屬-絕緣層-半導體閘極元件在飽和電流的表現是最好的，而掘入式金屬-絕緣層-半導體閘極元件與非掘入式比較下確實能將門檻電壓往增強型方向改進。閘極順向與反向漏電量測，金屬-絕緣層-半導體閘極元件較蕭基特閘極的漏電流小了四個級數以上。為了提高總電流大小，多根指叉型元件是較佳的選擇，其最大總電流可達到0.65A，電流密度為201mA/mm。
崩潰電壓方面，sample A的金屬-絕緣層-半導體閘極元件在基板浮動電位及浸泡在冷卻液中，Lgd=60-µm最高達到2261V，相較於蕭基特閘極最高的崩潰電壓2370V要低，此現象在sample B試片上也有相同情況產生。在漏電方面，金屬-絕緣層-半導體閘極元件相對於蕭基特閘極金屬元件擁有較低的漏電情況，而掘入式閘極元件由於漏電過大，容易達到1mA/mm的漏電崩潰機制，而使崩潰無法超過100V。

關鍵字

AlGaN ； GaN ； HEMT ； MIS

並列摘要

In this study, AlGaN/GaN HEMTs on a silicon substrate were fabricated. The devices of linear type and finger type are measured. There are two main topics in this study. One is to investigate the effects of three different gate structures, including Schottky gate, metal-insulator-semiconductor(MIS) gate, and recessed MIS gate. The other one is to compare the effects of different epi structures.Their breakdown behaviors will be compared
From the measurement results, among different gate structures,MIS gate devices have the largest saturation current. Compared with MIS gate, the recessed MIS gate devices can shift the threshold voltage from -12.13V to -5V, toward E-mode operation. In the measurement of forward and reverse gate bias, the MIS gate devices show at least 4 order lower gate leakage current than the Schottky gate devices.To enhance the total current, the multiple finger devices have been fabricated. The largest total current of a multiple finger device can achieve 0.65A, which corresponds to 201mA/mm.
On the breakdown characteristic, the highest breakdown voltage of a Schottky gate device is 2370V on sample A with Lgd=60-μm when the substrate is floating and the devices are tested with fluorinert immersion. However, the MIS gate devices show a lower breakdown voltage of. This phenomenon is also observed on sample B. On the other hand, the recessed MIS gate devices do not sustain more than 100V, because of a much larger gate leakage current.

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