利用氧化鋁/氮化矽保護層製作高功率氮化鋁鎵/氮化鎵蕭基二極體

Abstract

在研究中，我們專注在”高功率氮化鋁鎵/氮化鎵蕭基二極體”的製作，包括保護層選擇、嵌入式陽極結構和電場板。 在保護層選擇，我們利用電漿輔助化學氣相沈積(Plasma-Enhanced Chemical Vapor Deposition, PECVD)成長氮化矽、原子層沉積(Atomic Layer Deposition, ALD)成長高介電氧化鋁和氧化鋁/氮化矽雙層結構，比較元件的崩潰電壓的影響研究結果顯示氧化鋁能夠減少漏電流，並提高崩潰電壓。 為了降低蕭基二極體的導通電壓(Von)，我們利用嵌入式陽極結構方式，以電感偶合式電漿(Inductively-Coupled Plasma, ICP)搭配氯氣做乾蝕刻，蝕刻氮化鋁鎵以停在二維電子氣附近，再放上陽極金屬在嵌入式陽極結構，比較不同的蝕刻深度對導通電壓的變化。 模擬結果顯示，在陽極放置電場板，能夠提高正向電流與增加崩潰電壓，我們製作電場板結構比較其元件電性且結果如同模擬，正向電流與崩潰電壓皆提高。

In this study, we focused on the high performance AlGaN/GaN Schottky Barrier Diodes (SBDs) fabrication. The schemes include passivation layer selection, recessed anode structure and field plates. For the selection of the passivation layers, we compared the effects of traditional Si3N4 by plasma enhanced chemical vapor deposited (PECVD), high-K Al2O3 by atomic layer deposited (ALD) and double layer of Al2O3 / Si3N4 on the device breakdown voltage. High quality passivation film was found to reduce the device leakage current. For the purpose to reduce the SBD turn-on voltage (Von), we chose recessed anode method. We used inductively-coupled plasma (ICP) to etch over AlGaN epi layer nearing 2DEG channel. By putting anode metal on recessed structure, we compared the SBD Von for the different recessed depth. According to the simulation results, the field plates structure can shows improvement of the forward current and device breakdown voltage. We fabricate field plate structures and compare the devices performance as same as the simulation results.