Insights into the deposition rate and microstructure of polysilicon films: effect of different hydrogen dilution ratio

Abstract

Abstract:

Polycrystalline silicon thin film formation from inductively coupled plasma enhanced chemical vapor deposition system was studied. The dilution effect of H₂ on film deposition was discussed. The X-ray diffractometry, Raman spectra and scanning electron microscope measurement were carried out to analyze the influence of H₂ on the microstructures and the topography of polycrystalline silicon thin films. The optimum conditions for polycrystalline silicon thin films deposition were also discussed. The results indicated that polycrystalline silicon thin films with columnar structure crystals were fabricated on glass substrate. The deposition rate exhibited monotonic increase with Silane ratio R, a maximum deposition rate of 0.65nm⋅s^-1 was obtained. However, the crystal volume fraction of polycrystalline silicon thin films initially increased from 60.5% to 67.3%, and then slightly decreased with the increase of R. Therefore, the crystal has a maximum value of 67.3% at R=4.8%. The polycrystalline silicon thin films had a compact and well-arranged structure at this ratio. This structure can also increase carrier mobility and improve the efficiency of solar cells.

Key words: Inductively coupled plasma, Plasma enhanced chemical vapor deposition, Polycrystalline silicon thin films, H₂ dilution

摘要：

利用电感耦合等离子体增强化学气相沉积法(ICP-PECVD)直接在普通玻璃衬底上低温沉积多晶硅薄膜，主要研究了不同氢气稀释比例对薄膜沉积特性和微观结构的影响。采用 X 射线衍射仪(XRD)、拉曼光谱仪和扫描电子显微镜(SEM)表征了在不同氢气比例条件下所制备多晶硅薄膜的微结构、形貌，并对不同条件下样品的沉积速率进行了分析。实验结果表明：随着混合气体中硅烷比例的增加，薄膜的沉积速率不断增加；晶化率先增加，后减小；当硅烷含量为4.8%时，晶化率达到最大值67.3%。XRD 和 SEM 结果显示多晶硅薄膜在普通玻璃衬底上呈柱状生长，且晶粒排列整齐、致密，这种结构可提高载流子的纵向迁移率，有利于制备高效多晶硅薄膜太阳能电池。

关键词: 电感耦合等离子体, 等离子体增强化学气相沉积, 多晶硅薄膜, 氢气比例

CLC Number:

O539

SONG Sha-sha, ZUO Xiao, WEI Yu, CHEN Long-wei, SHU Xing-sheng . Insights into the deposition rate and microstructure of polysilicon films: effect of different hydrogen dilution ratio[J]. NUCLEAR FUSION AND PLASMA PHYSICS, 2014, 34(3): 275-281.

宋莎莎，左潇，魏钰，陈龙威，舒兴胜 . 氢气稀释比例对多晶硅薄膜微观结构和沉积特性的影响[J]. 核聚变与等离子体物理, 2014, 34(3): 275-281.

References

[1] Letha A J, Chan F M, Hwang H L. Anomalous effect of hydrogen dilution on the crystallinity of ICPCVD-grown silicon thin films at very low temperature[J]. J. Electr. Mater., 2010, 39: 39−42.
[2] 冯庆浩. 多晶硅薄膜的ECR-PECVD低温沉积及特性[D]. 辽宁: 大连理工大学, 2006.
[3] Li J, Wang J, Yin M, et al. Highly crystallized silicon films grown on glass without amorphous incubation layers by inductively coupledplasma chemical vapor deposition [J]. J. Crystal Growth, 2008, 310: 4340−4344.
[4] Wang J, Qin Y, Yan H, et al. Effects of the distance between the inductance coil and substrates on the microstructure and optical properties of silicon films deposited by ICP-CVD [J]. Phys. Procedia, 2011, 18:128−135.
[5] Kim K N, Lim J H, Jeong H B,et al. Linear inductive antenna design for large area flat panel display plasma processing [J]. Microelectronic Engineering, 2012, 89: 133−137.
[6] 黄锐, 林璇英, 余云鹏, 等. 氢稀释对多晶硅薄膜结构特性和光学特性的影响[J]. 物理学报, 2006, 55: 2523 −2528.
[7] 左潇, 魏钰, 陈龙威, 等. 微波电子回旋共振等离子体化学气相沉积法制备多晶硅薄膜[J]. 核聚变与等离子体物理, 2012, 32: 151−156.
[8] Ramalingam J, Maroudas D,Aydil E S. Atomistic simulation study of the interactions of SiH3 radicals with silicon surface [J]. J. Applied Physics, 1999, 86: 2872−2883.
[9] 杨根. 微晶硅薄膜的高速沉积研究[D]. 河南: 郑州大学, 2007.
[10] 常燕. 在柔性衬底上制备多晶硅薄膜的研究[D]. 浙江: 浙江大学, 2007.
[11] Wei D Y, Xiao S Q, Huang S Y, et al. Low-temperature deposition of μc-Si: H thin films by a low frequency inductively coupled plasma for photo voltaic applications[J]. J. Physics D: Applied Physics, 2013, 46: 215501.
[12] Xiao S Q, Xu S, Wei D Y, et al. From amorphous to microcrystalline: Phase transition in rapid synthesis of hydrogenated silicon thin film in low frequency inductively coupled plasma [J]. J. Applied Physics, 2010, 108: 113520.
[13] 吴自勤, 王兵. 薄膜生长[M]. 北京: 科学出版社, 2001. 210−213.
[14] Cheng Q, Xu S, Ostrikov K. Temperature−dependent properties of nc-Si thin films synthesized in low-pressure, thermally nonequilibrium, high-density inductively coupled plasma[J]. J. Physical Chemistry C, 2009, 113: 14759−14764. [15] Zhou H P, Wei D Y, Xu S, et al. Dilution effect of Ar/H2 on the microstructures and photovoltaic properties of nc-Si-H deposited in low frequency inductively coupled plasma[J]. J. Applied Physics, 2011, 110: 023517.
[16] 苏元军. ICP辅助磁控溅射制备多晶硅薄膜[D]. 辽宁: 大连理工大学, 2011.