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Hydrogenated amorphous silicon (a-Si: H) films have a wide range of practical applications, particularly in mirco-electromechanical system (MEMS), photovoltaic and photodetection. And plasma enhanced chemical vapor deposition (PECVD) is generally used as the deposition method of a-Si: H films for enabling large area deposition and high-quality film. Previous studies have demonstrated the fact of surface morphology of the PECVD-deposited a-Si film related to the substrate material[1-6]. Ref. [1] reported that smooth a-Si film without hillocks is formed on the 100 nm oxide/Si substrate while a rough surface with many hillocks is formed on the crystalline Si substrate. Ref. [2] discussed the influence of the PECVD parameters on the surface roughness of a-Si: H film, and the optimized deposition conditions to suppress the formation of gas bubbles in thick a-Si: H film deposited on silicon substrate. Ref. [3] considered some strategies to mitigate the formation of those micro-bubbles, and found a dramatic improvement in surface roughness quality in their experiment. In addition, some works have demonstrated that bubble defects are also formed on a-Si film after the process of annealing, which is resulted from the accumulation of hydrogen molecules on the film-substrate interface as hydrogen diffused from the film[4-6]. Previous works on the surface morphology of the PECVD-deposited a-Si film mainly focused on the bubble defects’ formation mechanism and the corresponding suppression methods, but ignored the potential applications of this kind of self-formed surface microstructure.
In this paper, we prepared a-Si: H film on crystalline silicon substrate, with nonuniformly distributed bubbles observed on the surface, which is consistent with the results in previous literatures. The latest advance in micro- and nano-fabrication lies in self-assembly or self-organization techniques[7-9], but to the best of our knowledge, few reports on this kind of novel self-formed technique. This technique has advantages in easier process and lower cost, indicates a high feasibility and a good prospect in the field of nanophotonics and MEMS.
A Self-Formed Silicon Surface Microstructure: Surface Characterization and Potential Applications
doi: 10.12178/1001-0548.2022206
- Received Date: 2022-07-05
- Rev Recd Date: 2022-09-29
- Available Online: 2024-04-01
- Publish Date: 2024-03-30
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Key words:
- MEMS /
- amorphous silicon films /
- blister defect /
- self-formed /
- silicon micro/nanostructures
Abstract: The morphology of hydrogenated amorphous silicon (a-Si: H) films grown by plasma enhanced chemical vapor deposition (PECVD) is studied. Nonuniformly distributed bubble defects are formed during the process of a-Si: H films deposited on crystalline silicon substrate. The SiNx/a-Si alternative layers are deposited on the as-prepared a-Si: H film, a perfect dome-shaped multi-shell microstructure was formed at the site of the blister defect, and no distinct structural collapse was observed. Three unique characters of the self-formed dome-shape microstructure are concluded, and the potential applications of the proposed self-formed dome-shape microstructure in nanophotonics and MEMS are also pointed out.
Citation: | LI Jiacheng, LIU Shuang, WU Shenglan, LIU Yong, ZHONG Zhiyong. A Self-Formed Silicon Surface Microstructure: Surface Characterization and Potential Applications[J]. Journal of University of Electronic Science and Technology of China, 2024, 53(2): 180-184. doi: 10.12178/1001-0548.2022206 |