具有氧化鋁/二氧化鈦鈍化層氮化銦鋁/氮化鋁/氮化鎵Γ-閘極結構金屬-氧化物-半導體場效異質結構電晶體研製

Abstract

本專題分別使用超音波噴霧熱裂解沉積法/RF濺鍍形成的具有複合氧化鋁/二氧化鈦鈍化氧化物的新型氧化鋁-電介質氮化銦鋁/氮化鋁/氮化鎵Γ-閘極金屬-氧化物-半導體異質結構場效電晶體（MOSHFET），本專題亦使用場板結構，分散汲極電場，因而提升元件崩潰特性，以及使用高 k 值閘極介電層改善閘極絕緣能力並達到鈍化表面缺陷的效果，以提升元件工作性能。Γ-閘極包括在氧化鋁電介質上的1微米長的有源閘極和複合氧化鋁/二氧化鈦氧化物上的1 微米長的場板。 目前的Γ-閘極金屬-氧化物-半導體異質結構場效電晶體具有優異的導通/截止電流比（I_on⁄I_off ）8.2×〖10〗^10，次臨界擺幅 102.3 mV/dec，最大外部跨導（g_(m,max)）210.1 mS/mm，最大汲極-源極飽和電流密度（I_(DS,max)）為 868.3 mA/mm，雙端斷態閘極-汲極崩潰電壓（〖BV〗_GD）為 - 311.2V，三端汲極-源極崩潰電壓（〖BV〗_DS）為 237V 在V_GS=-10V時，2.4 GHz 時的功率附加效率為 39.9 ％。為提供相關特性比較，本專題同時研製具有傳統蕭特基閘極平面結構、具有氧化鋁閘極介電層閘極結構、具有二氧化鈦閘極介電層閘極結構、具有場板-氧化鋁-二氧化鈦閘極介電層閘極結構以及具有場板-二氧化鈦-氧化鋁閘極介電層閘極結構之氮化銦鋁/氮化鋁/氮化鎵金屬高電子遷移率電晶體，所獲致之直流特性分別為：最大飽和電流密度I_(DS,max) (544.2 mA/mm、815.7 mA/mm、868.3 mA/mm)，無閘極偏壓飽和電流密度I_DSS0(291.1 mA/mm、256.3 mA/mm、670.4 mA/mm)，最大外質轉導g_(m,max) ( 221.2 mS/mm、194.7 mS/mm、210.1 mS/mm)，閘極漏電流I_g(1.4×10-2 mA/mm、4.1×10-3、5.1×10-9 mA/mm)，閘極-汲極兩端崩潰電壓〖BV〗_GD (-126 V、-143.5 V、-311.1 V)。目前的設計顯示出卓越的直流/射頻元件性能，適用於高功率射頻電路應用。 實驗結果顯示，本專題所研製具有場極板-二氧化鈦-氧化鋁閘極介電層結構之氮化銦鋁/氮化鋁/氮化鎵高電子遷移率電晶體，能有效改善元件直流特性，以及具有場極板提升元件的高壓特性。

The thesis investigates field-plate-Al2O3-TiO2-dielectric InAlN /AlN/GaN metal-oxide-semiconductor heterostructure field-effect transistors(MOS-HEMTs) with planar structure by using the ultrasonic spray pyrolysis deposition (USPD) and sputter technique to deposit oxide layer. Due to the enhanced gate control, the DC characteristic of device has been effectively improved. Depositing the high-k aluminum dioxide and titanium dioxide as a gate-dielectric layer, the gate leakage reduced by gate insulation and surface passivation. The Γ-gate includes a 1-µm long active gate on the Al2O3 dielectric and a 1-µm long field-plate on the composite Al2O3/TiO2 oxides. The present Γ-Gate MOS-HEMT has demonstrated excellent on/off current ratio(I_on⁄I_off ）8.2×〖10〗^10, subthreshold swing of 102.3 mV/dec, maximum extrinsic transconductance of (g_(m,max)) of 210.1 mS/mm, maximum drain-source saturation current density (I_(DS,max)) of 868.3 mA/mm, two-terminal offstate gate-drain breakdown voltage (〖BV〗_GD) of − 311.2 V, three-terminal drain-source breakdown voltage (〖BV〗_DS) of 237 V at V_GS=-10V, and power-added efficiency of 39.9% at 2.4 GHz. Providing the comparison of the characteristics, In this thesis, schottky-HEMT, Al2O3-MOS-HEMT, TiO2-MOS-HEMT, FP- Al2O3-TiO2-MOS- HEMT, and FP- TiO2- Al2O3-MOS-HEMT MOS Fin-HEMT have been achieved, including maximum drain-source saturation current density (I_(DS,max)) of 544.2 mA/mm, 810.4 mA/mm, 815.7 mA/mm, 858.2 mA/mm, and 868.3 mA/mm, drain-source current density at V_GS=0V (I_DSS0) of 291.1mA/mm, 331.3 mA/mm, 256.3mA/mm, 650.3 mA/mm, and 670.4 mA/mm, maximum extrinsic transconductance (g_(m,max)) of 212.2 mS/mm, 194.7 mS/mm and 210.1 mS/mm, gate leakage current (I_g) at V_GS=-10V of sample A to sample C were 1.4×10-2 mA/mm, 4.1×10-3 mA/mm and 5.1×10-9 mA/mm, two-terminal off-state gate-drain breakdown voltage (〖BV〗_GD) of 126 V, -143.5 V and -311.1 V, respectively, at 300 K. The present design has shown superior DC/RF device performance. It is suitable for high-power RF circuit applications. From the experiment results, the superior performance of FP-TiO2Al2O3 metal-oxide-semiconductor HEMTs (MOS-HEMT) can be effectively improve DC characteristics by sputter and USPD technique, and the field plate structure not only decrease leakage current but increase breakdown voltage of device.