Process Optimization for Fabrication of Self-Supporting Silicon Nitride Film Structure

Abstract

Abstract: Generally, the self-supporting silicon nitride film structure is based on micro-nano fabrication technology. Fabrication of self-supporting silicon nitride film structure was studied in this paper, in which parameters of dry etching and anisotropic wet etching were optimized to enhance the quality of self-supporting film structure. Dry etching process included reaction gas ratio and etching time, anisotropic wet etching process involved etchant concentration and etching temperature. First, the experiments were conducted with different parameters. Then the surface morphology of the films fabricated in these experiments were observed by optical microscope, during which the ideal process condition was obtained by comparing the results. It was found that the addition of oxygen to the reaction gas can improve the effect of dry etching, and the best ratio of etching gas is V(SF₆)∶V(CHF₃)∶V(O₂)=6∶37∶3, with 2 min etching time. In wet drying, etching with a mass fraction 25% etchant can achieve the maximum etching rate and ideal surface morphology of silicon nitride film.

Key words: silicon nitride, dry etching, anisotropic wet etching, single-crystal silicon, self-supporting film structure

CLC Number:

TB383

WANG Fuxiong, XIE Wanyi. Process Optimization for Fabrication of Self-Supporting Silicon Nitride Film Structure[J]. Journal of Synthetic Crystals, 2020, 49(12): 2358-2364.

References

[1] 赵毅红,陈荣发,刘伯实.Si₃N₄薄膜的成分与结构研究[J].真空,2004(4):71-73.
[2] Kovacs G T A, Maluf N I, Petersen K E. Bulk micromachining of silicon[J]. Proceedings of the IEEE, 1998, 86(8): 1536-1551.
[3] Dekker C. Solid-state nanopores[J]. Nature Nanotechnology, 2007, 2(4): 209-215.
[4] Li J, Gershow M, Stein D, et al. DNA molecules and configurations in a solid-state nanopore microscope[J]. Nature Materials, 2003, 2(9): 611-615.
[5] Yanagi I, Ishida T, Fujisaki K, et al. Fabrication of 3-nm-thick Si₃N₄ membranes for solid-state nanopores using the poly-Si sacrificial layer process[J]. Scientific Reports, 2015(5): 14656.
[6] Jutzi F, Wicaksono D H B, Pandraud G, et al. Far-infrared sensor with LPCVD-deposited low-stress Si-rich nitride absorber membrane Part 1.Optical absorptivity[J]. Sensors & Actuators A:Physical, 2009, 152(2): 119-125.
[7] Tellier C R. Anisotropic etching of silicon crystals in KOH solution[J].Journal of Materials Science, 1998, 33(1): 117-131.
[8] 马建,王欣,李堃,等.基于氮化硅薄膜纳米孔制备及DNA分子检测[J].东南大学学报(自然科学版),2017,47(2):265-270.
[9] 武灵芝,吴宏文,刘丽萍,等.基于聚焦离子束的氮化硅纳米孔的制备和表征[J].生物物理学报,2013,29(3):203-212.
[10] Biswas K, Kal S. Etch characteristics of KOH, TMAH and dual doped TMAH for bulk micromachining of silicon[J]. Microelectronics Journal, 2006, 37(6): 519-525.
[11] 张锦,冯伯儒,杜春雷,等.反应离子刻蚀工艺因素研究[J].光电工程,1997(24): 46-51.
[12] 苟君,吴志明,太惠玲,等.氮化硅的反应离子刻蚀研究[J].电子器件,2009(5): 864-866+870.
[13] Knizikevicius R, Kopustinskas V. Influence of temperature on the etching rate of SiO₂ in CF₄+O₂ plasma[J]. Microelectronic Engineering, 2006, 83(2): 193-196.
[14] 吴文娟,张松,韩培育,等.快速制备单晶Si片绒面的研究[J].人工晶体学报,2011,40(2): 352-358.
[15] Glembocki O J, Palik E D, De Guel G R. Hydration model for the molarity dependence of the etch rate of Si in aqueous alkali hydroxides[J]. Journal of the Electrochemical Society, 1991, 138(4): 1055-1063.
[16] Shikida M, Sato K, Tokoro K, et al. Comparison of anisotropic etching properties between KOH and TMAH solutions[C]. Twelfth IEEE International Conference on Micro Electro Mechanical Systems.IEEE, 2002.
[17] Shin Hyeon-Jin, Park In-Sung, Jang Yong-Ju, et al. Fabrication of free-standing nanoscale SiNx membranes with enhanced burst pressure via improved etching process[J]. Sensors & Actuators A:Physical, 2019(9): 297.