高功率氮化鋁鎵/氮化鎵高電子遷移率電晶體之製作與分析

The Fabrication and Analysis of High-Power AlGaN/GaN High Electron Mobility Transistor

葉榮博(Jung-Po Yeh)

指導教授 ： 管傑雄

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.00147

摘要

氮化鎵是一種相當穩定的寬能帶(3.4eV)半導體材料，常被應用於高壓元件中；又因具有直接能隙之特性，可作為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結構來製作出增強型操作之氮化鋁鎵/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）通入BCl3/Cl2/Ar有效提高蝕刻選擇比和降低蝕刻表面粗糙度的效果，以期對元件的損傷達到最低。另外，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。
在本篇論文中，我們將對製程方法進行研究，並討論金屬閘極和高介電係數氧化層的堆疊結構在退火製程下的可行性，並做結果的分析，期許未來可應用在氮化鎵高功率元件的製作上。

關鍵字

閘極氧化層 ； 氮化鋁鎵/氮化鎵 ； 原子沉積系統 ； 二維電子氣

並列摘要

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.
Enhancement mode 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 with BCl3/Cl2/Ar gas can effective improve the etching selectivity ratio and reduce surface roughness. 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, hafnium oxide can reduce the gate leakage and enhance the current density.
In this thesis,we research gate-last fabrication process and discuss metal-gate/high-κ dielectric stacks in the annealing process feasibility,We analyze the results, and hope that the process can be used to GaN fabrication in the future.

並列關鍵字

gate oxide ； AlGaN /GaN ； ALD ； 2DEG

參考文獻

[1] B. Jayant Baliga, “Trends in Power Semiconductor Devices”, IEEE Trans.

Bandgap Microwave Devices on DoD Systems”, Proceedings of the IEEE, vol.

Over 100 W n-GaN/n-AlGaN/GaN MIS-HEMT power amplifier for wireless

[5] E. Frayssinet, W. Knap, P. Lorenzini, N. Grandjean, J. Massies, C.

mode AIGaN/GaN HFET with selectively grown pn junction gate”, IEEE