電感耦合電漿蝕刻系統對氮化鎵蝕刻之研究

Abstract

GaN已被廣泛的運用在各種光電元件上，由於傳統的化學濕液蝕刻在三五元件製程上有許多不可避免的缺點；所以目前大多以電漿蝕刻的方式取代化學濕液蝕刻技術。本論文應用電感耦合電漿技術於氮化鎵材料的乾蝕刻及探討各項實驗操作因素對氮化鎵蝕刻結果的影響。半導體材料電漿蝕刻的結果會受到氣體流量、偏壓和壓力大小等參數的影響，造成其蝕刻速率、蝕刻後側壁的平滑度和斜率、表面的平滑度及型態等的不同。本實驗以 Cl2 和 BCl3 為蝕刻氣體，其混合比例對蝕刻的結果有相當大的影響，由數據顯示，當Cl2比例接近於90％時，可以得到較高的蝕刻速率。除此之外，添加了 CH4 氣體，可以減少Ga的殘留。另外偏壓的增加，使得蝕刻速率增加，但樣品表面的平整度下降。

In this thesis, we used inductively coupled plasma (ICP) etching system to etch GaN thin films and studied the effect of various experimental factors controlling the etching process. GaN-based semiconductor has been widely used for the fabrication of light-emitting diodes (LED), laser diodes (LD), and UV detectors on the photonic application and microwave power switches on the electronics application. The plasma etching technique has become the major patterning technique for the group-III nitrides due to the shortcomings in wet chemical etching. The dry etch characteristics are often dependent on plasma parameters including pressure, bias, and pressure. The etch rates, etch profile and etched surface morphology which are confirmed deposition of inter-level dielectric or passivation films, or epitaxial regrowth. In this study, we use Cl2 and BCl3 as the etching gases. For our experimental data, when the mix true ratio is 18:2(Cl2 : BCl3), we can get the maximum etching rate. The adding of CH4 gas in the process can improve the surface morphology of etched sample. For the factor of DC bias, we found that the etching rate will increase and surface morphology can be improved as the DC bias is increasing.