Study on silicon removal property and surface smoothing phenomenon by moderate-pressure microwave hydrogen plasma
Study on silicon removal property and surface smoothing phenomenon by moderate-pressure microwave hydrogen plasma
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DOI：
10.1016/j.mssp.2021.105780
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发表时间：
2021-07
影响因子：
4.1
通讯作者：
H. Ohmi;K. Kimoto;T. Nomura;H. Kakiuchi;K. Yasutake
中科院分区：
文献类型：
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作者：
H. Ohmi;K. Kimoto;T. Nomura;H. Kakiuchi;K. Yasutake
研究了局域微波氢等离子体去除硅的性能。等离子体发生参数（输入功率，H2气体流量，和初始表面粗糙度）和去除性能（蚀刻速率和表面粗糙度）之间的关系被揭示。应力释放和去除受影响的硅层的H2等离子体蚀刻也被证明。此外，这种H2等离子体蚀刻技术呈现出没有蚀刻速率依赖于晶面取向。因此，即使多晶Si样品被蚀刻，也可以露出镜面。此外，利用H2等离子体刻蚀可以在不破坏样品的情况下将100 μ m厚的Si样品减薄到5.7 μm。腐蚀后的硅样品的表面粗糙度取决于腐蚀速率。存在一个临界腐蚀速率，它决定了腐蚀后的硅表面是粗糙还是光滑。当刻蚀速率明显低于临界刻蚀速率时，由于H原子在Si晶体中诱导形成{111}片状缺陷，导致表面粗糙度增大。相反，当蚀刻速率高于临界值时，粗糙度形成被抑制，并且尽管向Si表面供应高H通量，Si表面也变得光滑。通过比较H原子在Si中的扩散速率和刻蚀速率，讨论了粗糙度形成的抑制。重要的是保持Si蚀刻速率高于H扩散速率以获得平滑的蚀刻Si表面。
The Si removal property achieved by a localized microwave hydrogen plasma was investigated. The relationship between plasma generation parameters (input power, H2gas flow rate, and initial surface roughness) and the removal property (etching rate and surface roughness) was revealed. Stress relief and removal of the affected Si layer by H2plasma etching were also demonstrated. Moreover, this H2plasma etching technique presents no etching-rate dependence on the crystal plane orientation. Therefore, even though a multi-crystalline Si sample was etched, a mirror surface could be revealed. In addition, a 100-μm-thick Si sample could be thinned to 5.7 μm by H2plasma etching without breaking the sample. The surface roughness of the etched Si sample depends on the etching rate. A critical etching rate exists, which determines whether the etched Si surface becomes rough or smooth. When the etching rate is significantly lower than the critical etching rate, large surface roughness is generated owing to the formation of {111} platelet defects induced by H atoms in Si crystal. By contrast, when the etching rate is higher than the critical value, the roughness formation is suppressed, and the Si surface becomes smooth despite the high H flux supplied to the Si surface. The suppression of roughness formation is discussed by comparing the etching rate with the diffusion rate of H atoms into Si. It is important to maintain the Si etching rate higher than the H diffusion rate to obtain a smooth etched Si surface.