金屬閘極/高介電係數氧化層技術在氮化鎵電晶體之應用

Abstract

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。 在氮化鎵元件製程方面，因大多採用離子植入製作源極和汲極，高溫的退火處理無法避免，所以大多採用後閘極製程(Gate-Last)技術。在本篇論文中，我們將對製程方法進行研究，分為先閘極製程(Gate-First)和後閘極製程作探討，並討論金屬閘極和高介電係數氧化層的堆疊結構在兩種不同製程方式下應用的可行性，並做結果的分析，期許未來可應用在氮化鎵元件的製作上。

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. In the fabrication process of GaN, because we usually use ion-implantation to form source and drain, the high-temperature annealing is not avoidable. Thus, in majority of references, they commonly adopt gate-last process. In this thesis, we research gate-first and gate-last fabrication process with metal-gate/high-κ dielectric stacks, and consider the applicable feasibility on GaN fabrication technique. We analyze the results, and hope that the process can be used to GaN fabrication in the future.