Cl2/BCl3感应耦合等离子体GaN刻蚀侧壁形貌研究

基于感应耦合等离子体干法刻蚀技术,对采用Cl2/BCl3气体组分下GaN刻蚀后的侧壁形貌进行了研究。扫描电镜(SEM)结果表明,一定刻蚀条件下,刻蚀后GaN侧壁会形成转角与条纹状褶皱形貌。进一步实验,观察到了GaN侧壁转角形貌的形成过程;低偏压功率实验表明,高能离子轰击是GaN侧壁转角与条纹状褶皱形貌形成的原因。刻蚀过程中,掩蔽层光刻胶经过高能离子一段时间轰击后,其边缘首先出现条纹状褶皱形貌,并转移到GaN侧壁上,接着转角形貌亦随之出现并转移到GaN侧壁上。这与已公开发表文献认为的GaN侧壁条纹状褶皱仅由于掩蔽层边缘粗糙所引起而非刻蚀过程中形成的解释不同。

Sidewall Topography of GaN Etching Using Cl2/BCl3 Inductively Coupled Plasma

The sidewall topography of GaN was etched by Cl2/BCl3 plasma based on inductively coupled plasma(ICP) dry etching.A "turn" and striations in the sidewall were found by scanning electron microscope under certain conditions.The formation process of the turn was showed by further experiments.And the low-bias-power experiment shows that the bombardment of energetic ions is the reason for the turn and striations on the sidewall of GaN.Striations in the sidewall of photoresist mask were formed firstly after energetic ions bombarding during etching and transferred to the sidewall of GaN,and the turn was formed following striations in the sidewall of PR.The explanation for striations in the sidewall of GaN was different from the published one that striations came from the imperfections in the photoresist mask.