高性能氮化鋁鎵/氮化鎵電晶體之製作與分析

Abstract

氮化鎵是一種極為穩定且寬能帶(3.4eV)半導體材料，常應用在高壓元件中；又因具有直接能隙之特性，可應用在405 奈米的短波長發光二極體(LED)光源。此外，氮化鎵/氮化鋁鎵的異質結構因擁有高濃度的二維電子氣(2DEG)，故具有相當卓越的載子傳輸特性和極高的電子漂移率，可被應用於高功率、高頻率的電路操作之中，是目前極為熱門的半導體材料之一。 本論文主要利用閘極掘入的方式搭配MIS結構來製作出氮化鋁鎵/氮化鎵場效功率電晶體，利用高密度活性離子蝕刻系統（HDP-RIE）來做掘入式閘極。此外，閘極氧化層材料我們利用原子沉積系統 (Atomic layer deposited, ALD)成長高介電係數材料像是氧化鋁、二氧化鉿來當作閘極介電層，可有效降低閘極漏電流及提升電流密度；且在疊閘極氧化層之前，會對AlGaN表面做爐管退火處理，以期將臨限電壓調變至接近零伏特。

GaN is a stable semiconductor material with wide bandgap of 3.4eV which can apply to high-voltage devices, and because of its direct-bandgap property, we commonly used in bright LED of short wavelength with 405nm. In addition, AlGaN/GaN hetero-junction has outstanding carrier transport property and high electron mobility because of the existence of two-dimensional electron gas with high concentration, and we can apply to high-power and high-frequency circuit operation. Currently, GaN is one of the most attractive semiconductor materials. AlGaN/GaN MOSFETs fabricated by gate recessed technique and MIS structure is mentioned in this study. Reactive ion etching using a high-density systems (HDP-RIE) dry etch the gate recessed area. Hope to reduce the element of damage. Furthermore, the gate dielectric material grew by ALD (Atomic Layer Deposited) with high k such as aluminum oxide or hafnium oxide can reduce the gate leakage and enhance the current density. Before depositing the gate dielectric, we will go about furnace annealing for the device. Threshold voltage can modulate to near-zero volt.