Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
권호 표지
DOI QR코드

DOI QR Code

Effects of Ar Addition on the Etch Rates and Etch Profiles of Si Substrates During the Bosch Process

Bosch 공정에서 Si 식각속도와 식각프로파일에 대한 Ar 첨가의 영향

  • Ji, Jung Min (Department of Chemical Engineering, Division of Energy Systems Research, Ajou University) ;
  • Cho, Sung-Woon (Department of Chemical Engineering, Division of Energy Systems Research, Ajou University) ;
  • Kim, Chang-Koo (Department of Chemical Engineering, Division of Energy Systems Research, Ajou University)
  • 지정민 (아주대학교 화학공학과, 에너지시스템학과) ;
  • 조성운 (아주대학교 화학공학과, 에너지시스템학과) ;
  • 김창구 (아주대학교 화학공학과, 에너지시스템학과)
  • Received : 2013.07.29
  • Accepted : 2013.09.25
  • Published : 2013.12.01
Download PDF
⟨ Previous Next ⟩

Abstract

The etch rate and etch profile of Si was investigated when Ar was added to an $SF_6$ plasma in the etch step of the Bosch process. A Si substrate was etched with the Bosch process using $SF_6$ and $SF_6$/Ar plasmas, respectively, in the etch step to analyze the effects of Ar addition on the etch characteristics of Si. When the Ar flow rate in the $SF_6$ plasma was increased, the etch rate of the Si substrate increased, had a maximum at 20% of the Ar flow rate, and then decreased. This was because the addition of Ar to the $SF_6$ plasma in the etch step of the Bosch process resulted in the bombardment of Ar ions on the Si substrate. This enhanced the chemical reactions (thus etch rates) between F radicals and Si as well as led to sputtering of Si particles. Consequently, the etch rate was higher more than 10% and the etch profile was more anisotropic when the Si substrate was etched with the Bosch process using a $SF_6$/Ar (20% of Ar flow rate) plasma during the etch step. This work revealed a feasibility to improve the etch rate and anisotropic etch profile of Si performed with the Bosch process.

Bosch 공정의 식각 단계에서 Ar을 첨가하였을 때 Si의 식각특성을 관찰하기 위하여 식각 단계에서 $SF_6$ 플라즈마만 사용한 경우와 Ar 유속비율이 20%인 $SF_6$/Ar 플라즈마를 각각 사용하여 Si을 Bosch 공정으로 식각하였다. Bosch 공정의 식각 단계에서 $SF_6$ 플라즈마에 Ar 가스를 첨가하면 $Ar^+$ 이온에 의한 이온포격이 증가하였고 이는 Si 입자의 스퍼터링을 초래할 뿐 아니라 F 라디칼과 Si의 화학반응을 가속하였다. 그 결과 식각 단계에서 20%의 Ar이 첨가되어 Bosch 공정으로 수행된 Si의 식각속도는 Ar이 첨가되지 않은 경우보다 10% 이상 빨라졌고 식각프로파일도 더욱 비등방적이었다. 이 연구의 결과는 Bosch 공정으로 Si을 식각할 때 식각속도와 식각프로파일의 비등방성을 개선하는데 필요한 기초자료로 사용될 수 있을 것으로 판단된다.

Keywords

References

  1. Yun, H. J., Kim, T. H., Shin, C. B., Kim, C.-K., Min, J.-H. and Moon, S. H., "Comparison of Atomic Scale Etching of Poly-Si in Inductively Coupled Ar and He Plasmas," Korean J. Chem. Eng., 24, 670-673(2007). https://doi.org/10.1007/s11814-007-0023-9
  2. Aachboun, S. and Ranson, P., "Deep Anisotropic Etching of Silicon," J. Vac. Sci. Technol. A, 17, 2270-2273(1999). https://doi.org/10.1116/1.581759
  3. Lee, W. G, "Characteristics of Amorphous Silicon Gate Etching in $Cl_2$/HBr/$O_2$ High Density Plasma," Korean Chem. Eng. Res. (HWAHAK KONGHAK), 47, 79-83(2009).
  4. Kang, S.-K., Min, J.-H., Lee, J.-K. and Moon, S. H. "Effects of Bias Voltage and Ion-incident Angle on the Etching of Photoresist in a High-density $CHF_3$ Plasma," Korean Chem. Eng. Res.(HWAHAK KONGHAK), 44, 498-504(2006).
  5. Laermer, F. and Schilp. A., U.S. Patent No. 5,501,893(1996).
  6. Tachi, S., Tsujimoto, K. and Sadayuki, O., "Low-temperature Reactive Ion Etching and Microwave Plasma Etching of Silicon," Appl. Phys. Lett., 52, 616-618(1988). https://doi.org/10.1063/1.99382
  7. Volland, B., Shi, F., Hudek, P., Heerlein, H. and Rangelow, I. W., "Dry Etching with Gas Chopping without Rippled Sidewalls," J. Vac. Sci. Technol. B, 17, 2768-2771(1999). https://doi.org/10.1116/1.591061
  8. Rangelow, I. W., "Critical Tasks in High Aspect Ratio Silicon Dry Etching for Microelectromechanical Systems," J. Vac. Sci. Technol. A, 21, 1550-1562(2003).
  9. Blauw, M. A., Zijlstra, T. and van der Drift, E., "Balancing the Etching and Passivation in Time-Multiplexed Deep Dry Etching of Silicon," J. Vac. Sci. Technol. B, 19, 2930-2934(2001). https://doi.org/10.1116/1.1415511
  10. Blauw, M. A., Craciun, G., Sloof, W. G., French, P. J. and van der Drift, E., "Advanced Time-Multiplexed Plasma Etching of High Aspect Ratio Silicon Structures," J. Vac. Sci. Technol. B, 20, 3106-3110(2002). https://doi.org/10.1116/1.1518018
  11. Abdolvand, R. and Ayazi, F., "An Advanced Reactive Ion Etching Process for Very High Aspect-Ratio Sub-Micron Wide Trenches in Silicon," Senss. Actuator A-Phys., 144, 109-116(2008). https://doi.org/10.1016/j.sna.2007.12.026
  12. Rhee, H., Kwon, H., Kim, C.-K., Kim, H. J., Yoo, J. and Kim, Y. W., "Comparison of Deep Silicon Etching Using $SF_6$/$C_4F_8$ and $SF_6$/$C_4F_6$ Plasmas in the Bosch Process," J. Vac. Sci. Technol. B, 26, 576-581(2008). https://doi.org/10.1116/1.2884763
  13. Rhee, H., Lee. H. M., Namkoung, Y. M., Kim, C.-K., Chae, H. and Kim, Y. W., "Dependence of Etch Rates of Silicon Substrates on the Use of $C_4F_8$ and $C_4F_6$ Plasmas in the Deposition Step of the Bosch Process," J. Vac. Sci. Technol. B, 27, 33-40(2009). https://doi.org/10.1116/1.3039690
  14. Hedlund, C., Jonsson, L. B., Katardjiev, I. V., Berg, S. and Blom, H.-O., "Angular Dependence of the Polysilicon Etch Rate during Dry Etching in $SF_6$ and $Cl_2$," J. Vac. Sci. Technol. A, 15, 686-691(1997). https://doi.org/10.1116/1.580802
  15. Min, J.-H., Lee, G.-R., Lee, J.-K., Moon, S. H. and Kim, C.-K., "Dependences of Bottom and Sidewall Etch Rates on Bias Voltage and Source Power during the Etching of Poly-Si and Fluorocarbon Polymer Using $SF_6$, $C_4F_8$, and $O_2$ Plasmas," J. Vac. Sci. Technol. B, 22, 893-901(2004). https://doi.org/10.1116/1.1695338