本論文針對挖洞式無金氮化鎵歐姆接觸研究，再應用到氮化鎵高電子遷移率電晶體進行電性探討與研究。研究包含磊晶片材料分析、元件的設計與製作、直流電性與動態特性分析以及Silvaco TCAD的模擬。 對於氮化鋁鎵/氮化鎵之磊晶片而言，先回顧金歐姆接觸之氮化鋁鎵/氮化鎵高電子遷移率電晶體之歐姆接觸、直流電性以及動態特性討論。根據結果顯示，在挖洞深度以及挖洞圖形為5.5 nm與1/3/5 μm的條件下，可獲得最佳之歐姆接觸電阻(RC = 0.89 Ω?mm)；以此條件製作挖洞式金歐姆接觸之氮化鋁鎵/氮化鎵高電子遷移率電晶體並與無挖洞式金歐姆接觸之電晶體進行電性比較。結果顯示挖洞式設計降低歐姆接觸電阻可使元件直流特性獲得改善，但在動態特性方面則出現嚴重的電流崩塌現象。採用無金歐姆金屬搭配低溫(550 ℃)熱退火的方式製作之歐姆接觸，並進行元件直流電性以及動態特性分析。結果顯示，在挖洞深度以及挖洞圖形為27.5 nm與1/3/5 μm的條件下，可獲得最佳之歐姆接觸電阻(RC = 0.98 Ω?mm)，並以此條件製作挖洞式無金歐姆接觸之氮化鋁鎵/氮化鎵高電子遷移率電晶體，結果呈現相比挖洞式金歐姆接觸之電晶體，改善了元件崩潰電壓特性以及電流崩塌的問題。研究顯示無金歐姆金屬搭配低溫熱退火不僅解決了原本含金製程之CMOS元件製程流程不兼容的問題，還可以改善元件特性。此外，對於具備低片電阻之氮化鋁銦鎵/氮化鎵(AlInGaN/GaN)磊晶片而言，1/3/5 μm的挖洞式圖形亦可獲得最佳歐姆接觸電阻(RC = 1.14 Ω?mm)，以此條件製作挖洞式無金歐姆接觸之電晶體，並進行電性分析。 ;This paper focuses on the study of the Au-free recessed ohmic contact GaN, and then applies it to the GaN HEMTs for electrical discussion and research. The research includes epitaxy structures material, device fabrication, electrical analysis, and Silvaco TCAD simulation. For AlGaN/GaN epitaxial structures, this study reviews the ohmic contact, electrical characteristics analysis results of Au-based AlGaN/GaN HEMT. The best ohmic contact resistance (RC = 0.89 Ω?mm) can be obtained under the conditions of the recess depth and the recess pattern are 5.5 nm and 1/3/5 μm, and make Au-based recessed ohmic contact AlGaN/GaN HEMT under this condition and compare with Au-based non-recessed ohmic contact AlGaN/GaN HEMT. The results show that the recess pattern design reduces the ohmic contact resistance to improve the electrical characteristics, but there is a serious current collapse in the dynamic characteristics. Therefore, this study uses Au-free ohmic metal with 550 ℃ low annealing temperature to explore the analysis of ohmic contact and electrical characteristics. According to the results, the best ohmic contact resistance (RC = 0.98 Ω?mm) can be obtained when the recess depth and the recess pattern are 27.5 nm and 1/3/5 μm, and the Au-free recessed ohmic contact AlGaN/GaN HEMT is fabricated under this condition. The results show that compared to the Au-based recessed ohmic contact HEMTs, the problems of device breakdown voltage characteristics and current collapse are improved. The research has shown that Au-free ohmic metal with low annealing temperature not only solves the problem of CMOS technology incompatibility but also improves the problem of device characteristics. In addition, for AlInGaN/GaN epitaxial structure with low sheet resistance, a recess pattern of 1/3/5 μm can also obtain the best ohmic contact resistance (RC = 1.14 Ω?mm), and the Au-free recessed ohmic contact AlInGaN/GaN HEMT is fabricated under this condition for electrical analysis.
