n型矽(100)表面在塗佈奈米銀後於含過氧化氫之氟化銨水溶液中的暗室蝕刻行為

n-Si (100) Coated with Sparse Ag Nano-Particles Under Dark Etching in Aqueous NH4F with the Aid of H2O2

莊政霖(Cheng-Lin Chuang)

指導教授 ： 林景崎

國立中央大學/工學院/機械工程學系/博士(2012年)

摘要

本論文之內容主要探討奈米銀顆粒塗佈於n-型(100)單晶矽上，在不照光的條件下利用不同濃度之氟化銨和過氧化氫的混合溶液，經化學蝕刻後控制其孔洞形貌特性研究。研究發現蝕刻液加入的過氧化氫濃度越高(1 M ~ 5 M)會使得OCP之氧化還原電位往正電位移動，且高濃度的蝕刻液(11 M NH4F )其電位比低濃度蝕刻液(1 M NH4F)來的低，另外SEM結果顯示利用化學蝕刻法在1 M NH4F + 5 M H2O2混合蝕刻液中蝕刻五小時，可將塗佈奈米銀顆粒的矽晶表面蝕刻出直徑約1.5 ~ 3.1μm、深度約可達15 ~ 20μm(孔璧上有100 ~ 150 nm的奈米孔)的多孔矽，相較於在11 M NH4F + 5 M H2O2系統下只能發現淺孔洞；進一步利用XPS分析確認表面為矽與二氧化矽的化學鍵結分別在99.3 eV 和103.4 eV，同時藉由交流阻抗量測法可發現Nyquist圖中有兩個明顯的容抗頻譜分別在高頻與低頻產生，在頻率相角圖也可發現在高頻和低頻分別出現兩個時間常數的變化分別代表氧化層的容抗頻譜與矽腐蝕的容抗頻譜訊號。

關鍵字

多孔矽 ； 金屬輔助化學蝕刻 ； 氟化銨

並列摘要

Single crystalline n-Si (100) previously coated with sparse silver nano-particles were immersed in various solutions of ammonium fluoride and hydrogen peroxide to investigate and control their morphology of wet etching under no illumination. In the absence of H2O2, the open circuit potential (OCP) of the silicon was more active in the solutions of 11.0 M than 1.0 M NH4F. In the present of H2O2, the OCP of the silicon increased with increasing the concentration of H2O2 (from 1.0 to 5.0 M). Through examination by scanning electron microscopy (SEM), it exhibited porous surface consisting of micro-pores (1.5 ~ 3.1 μm in diameter with 15 ~ 20μm in depth) where nano-pores (100 ~ 150 nm in diameter) were embedded inside for the etching duration prolonged for 5 h in 1 M NH4F + 5 M H2O2. In contrast, only a few shallow pores on the Si (100) surface could be formed after the etching conducted in 11.0 M NH4F + 5.0 M H2O2. By checking the surface chemical bonding of silicon and silica in the NH4F/H2O2 system shows two important points at 99.3 eV and 103.4 eV. The Nyquist plot for this system indicated two typical semicircles, in which the one in response to high frequencies revealed greater diameter and the other in response to low frequencies indicated smaller diameter. This mechanism could be reconfirmed to have two time constants by checking the plots of phase angle against the exerted frequencies, respectively indicating the generation of an oxide layer on the surface of the substrate and the occurrence of an etching reaction at the controlled interface.

並列關鍵字

Porous silicon ； Ammonium fluoride ； Metal-assist etch

參考文獻

[43] Z. P. Huang, X. X. Zhang, M. Reiche, L. F. Liu, W. Lee, T. Shimizu, and S. Senz, U. Gosele, Nano Lett., 8 (2008) 3046.

[37] M. L. Zhang, C. Q. Yi, X. Fan, K. Q. Peng, N. B. Wong, M. S. Yang, R. Q. Zhang, and S. T. Lee, Appl. Phys. Lett., 92 (2008) 043116.

[42] Z. P. Huang, H. Fang, and J. Zhu, Adv. Mater., 19 (2007) 744.

[55] J. C. Lin, C. M. Lai, W. D. Jehng, K. L. Hsueh, S. L. Lee, J. Electrochem. Soc., 155 (2008) D436.

[48] L. A. Jones, O. Yukseker, and D. F. Thomas, J. Vac. Sci. Technol., A14 (1996) 1505.