Determination of etching parameters for pulsed XeF2 etching of silicon using chamber pressure data

Dipta Sarkar, M. G. Baboly, M. M. Elahi, K. Abbas, J. Butner, D. Pinon, T. L. Ward, Tyler Hieber, Austin Schuberth, Z. C. Leseman

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

A technique is presented for determination of the depletion of the etchant, etched depth, and instantaneous etch rate for Si etching with XeF2 in a pulsed etching system in real time. The only experimental data required is the pressure data collected temporally. Coupling the pressure data with the knowledge of the chemical reactions allows for the determination of the etching parameters of interest. Using this technique, it is revealed that pulsed etching processes are nonlinear, with the initial etch rate being the highest and monotonically decreasing as the etchant is depleted. With the pulsed etching system introduced in this paper, the highest instantaneous etch rate of silicon was recorded to be 19.5 μm min-1 for an initial pressure of 1.2 Torr for XeF2. Additionally, the same data is used to determine the rate constant for the reaction of XeF2 with Si; the reaction is determined to be second order in nature. The effect of varying the exposed surface area of Si as well as the effect that pressure has on the instantaneous etch rate as a function of time is shown applying the same technique. As a proof of concept, an AlN resonator is released using XeF2 pulses to remove a sacrificial poly-Si layer.

Original languageEnglish (US)
Article number045007
JournalJournal of Micromechanics and Microengineering
Volume28
Issue number4
DOIs
StatePublished - Feb 15 2018

Keywords

  • XeF
  • etch rate
  • etching technique
  • pulsed etching
  • silicon

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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