本篇論文使用在氮化鎵基板上以MBE成長之氮化鎵試片製作垂直型溝槽式閘極MOSFET，探討以ALD沉積不同閘極氧化層及歐姆接觸之快速熱退火製程對元件電性的影響。
本次實驗之試片變因分別為： (A) 以80 nm Al2O3做為閘極氧化層並在氮氣環境下進行850°C 30秒之歐姆接觸快速熱退火。(B) 以80 nm Al2O3做為閘極氧化層但不經過快速熱退火。(C)以40 nm Al2O3/40 nm SiO2做為閘極氧化層且不經過快速熱退火。(D) 以40 nm SiO2/40 nm Al2O3做為閘極氧化層且不經過快速熱退火。
元件製作完成後發現其中有大量的Trap，必須以Pulse模式量測並且在UV光的照射下才會有較合理的直流特性。由Sample A發現快速熱退火會降低元件的電流密度。由雙向ID-VG發現Sample C相對於Sample D有較大的遲滯。
整體而言，由於Sample B的閘極氧化層使用80nm高介電系數的Al2O3並且未經高溫快速熱退火製程，因此有較好的元件順向特性，Vth為8.2 V，電流密度可達5 A/mm2，Ron,sp約為7.71 mΩ-cm2。而元件漏電流偏大，崩潰電壓只有約200 V左右。

In this thesis, we fabricated vertical trench gate GaN MOSFETs on MBE grown epitaxial layers on GaN substrates, and investigated the effects on device characteristics from different ALD gate insulators and RTA process for ohmic contacts.
The samples of this experiment included: (A) a 80 nm Al2O3 as the gate insulator with RTA at 850°C in N2 ambient for 30s for ohmic contact. (B) a 80 nm Al2O3 as the gate insulator without RTA. (C) a 40 nm Al2O3/40 nm SiO2 as the gate insulator without RTA.(D) a 40 nm SiO2/40 nm Al2O3 as the gate insulator without RTA.
It was observed that there were a significant amount of traps introduced in the device after processing. These devices had to be measured by pulse mode and under UV light to show reasonable DC characteristics. It was also found that the current density was reduced by RTA from sample A. And from sweeping ID-VG in both directions, the hysteresis for sample C is larger than sample D.
In general, Sample B shows better forward characteristics due to a 80nm high dielectric constant Al2O3 as the gate insulator and the elimination of high temperature RTA. The Vth is 8.2 V, the current density reaches 5 A/mm2, and the Ron,sp is about 7.71 mΩ-cm2. The breakdown voltage is about 200 V with a large leakage current.

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