Deep Reactive Ion Etching (DRIE) - The Bosch Process, Slides of Nanomaterial Engineering

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DRIE - Bosch

process (Si)

What is the

Bosch Process?

Why is it

important to

separate film

deposition and

etching steps?

Different

sidewall

profiles with

Bosch process

Process Flexibility High etch rates High selectivity to photoresist (PR) and oxide High Aspect- ratio Smooth sidewalls Minimised mask undercut SOI capability Si thinning & high Si exposed Capable SiO 2 etch

Process

Benefits

Application of

Bosch Process

MEMS

TSV Via Hole

Fabrication

Pillar

Fabrication

MEMS

TSV(Through- Silicon Via) Via Hole Fabrication There are several requirements in via hole etching for TSV:

1. No undercut below the mask at the upper and wide edge of the TSV Undercut prevents insulation layer deposition on sidewalls. 2. Smooth and tapered sidewalls Rough sidewalls deteriorate step coverage of diffusion barrier and copper seed layers by sputtering. 3. Scallop size reduction Leakage is caused by copper plug peeling or delamination. 4. Rounded corner on the hole bottom Rounded profile is preferred to prevent breakdown with the concentration of electric fields on the bottom.

References

• Kokkoris, G., Goodyear, A., Cooke, M. and Gogolides, E. A global model for C4F8 plasmas coupling gas phase and wall surface reaction kinetics, Journal of Physics D: Applied Physics, 41, 19 (2008), 195211.
• Laerme, F., Schilp, A., Funk, K. and Offenberg, M. Bosch deep silicon etching: improving uniformity and etch rate for advanced MEMS applications, Technical Digest. IEEE International MEMS 99 Conference. Twelfth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No. 99CH36291)IEEE (1999).
• (^) Nagaseki, K., Kobayashi, H., Ishikawa, I., Nishimura, E., Saito, Y. and Suganomata, S. Mass spectrometry of discharge products at 13.56 MHz in SF6 gas, Japanese journal of applied physics, 33, 7S (1994), 4348.
• Rangelow, I. W. Critical tasks in high aspect ratio silicon dry etching for microelectromechanical systems, Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 21, 4 (2003), 1550–1562.
• (^) Wu, B., Kumar, A. and Pamarthy, S. High aspect ratio silicon etch: A review, Journal of applied physics, 108, 5 (2010), 9.
• https://www.samcointl.com/opto/portfolio/si-dr
• https://www.spts.com/resources/tech-insights/intro-to-silicon-DRI E-etching
• (^) https://plasma.oxinst.com/technology/deep-reactive-ion-etching

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