Etching of silicon in alkaline solutions: A critical look at the {111} minimum

A.J. Nijdam, J. van Suchtelen, Johan W. Berenschot, Johannes G.E. Gardeniers, Michael Curt Elwenspoek

  • 11 Citations

Abstract

Anisotropic wet-chemical etching of silicon in alkaline solutions is a key technology in the fabrication of sensors and actuators. In this technology, etching through masks is used for fast and reproducible shaping of micromechanical structures. The etch rates R{hkl} depend mainly on composition and temperature of the etchant. In a plot of etch rate versus orientation, there is always a deep, cusped minimum for the {111} orientations. We have investigated the height of the {111} etch-rate minimum, as well as the etching mechanisms that determine it. We found that in situations where masks are involved, the height of the {111} minimum can be influenced by nucleation at a silicon/mask-junction. A junction which influences etch or growth rates in this way can be recognized as a velocity source, a mathematical concept developed by us that is also applicable to dislocations and grain boundaries. The activity of a velocity source depends on the angle between the relevant {111} plane and the mask, and can thus have different values at opposite {111} sides of a thin wall etched in a micromechanical structure. This observation explains the little understood spread in published data on etch rate of {111} and the anisotropy factor (often defined as R100/R111).
Original languageUndefined
Pages (from-to)430-434
Number of pages5
JournalJournal of crystal growth
Volume198-19
Issue number198/199
DOIs
StatePublished - 2 Mar 1999

Fingerprint

Masks
Etching
Silicon
Wet etching
Dislocations (crystals)
Grain boundaries
Anisotropy
Nucleation
Actuators
Fabrication
Sensors
Chemical analysis
Temperature

Keywords

  • METIS-111697
  • IR-14610
  • Anisotropic etching
  • Anisotropy factor
  • EWI-13209
  • Surface morphology
  • Kinematic wave theory
  • Silicon

Cite this

Nijdam, A.J.; van Suchtelen, J.; Berenschot, Johan W.; Gardeniers, Johannes G.E.; Elwenspoek, Michael Curt / Etching of silicon in alkaline solutions: A critical look at the {111} minimum.

In: Journal of crystal growth, Vol. 198-19, No. 198/199, 02.03.1999, p. 430-434.

Research output: Scientific - peer-reviewArticle

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title = "Etching of silicon in alkaline solutions: A critical look at the {111} minimum",
abstract = "Anisotropic wet-chemical etching of silicon in alkaline solutions is a key technology in the fabrication of sensors and actuators. In this technology, etching through masks is used for fast and reproducible shaping of micromechanical structures. The etch rates R{hkl} depend mainly on composition and temperature of the etchant. In a plot of etch rate versus orientation, there is always a deep, cusped minimum for the {111} orientations. We have investigated the height of the {111} etch-rate minimum, as well as the etching mechanisms that determine it. We found that in situations where masks are involved, the height of the {111} minimum can be influenced by nucleation at a silicon/mask-junction. A junction which influences etch or growth rates in this way can be recognized as a velocity source, a mathematical concept developed by us that is also applicable to dislocations and grain boundaries. The activity of a velocity source depends on the angle between the relevant {111} plane and the mask, and can thus have different values at opposite {111} sides of a thin wall etched in a micromechanical structure. This observation explains the little understood spread in published data on etch rate of {111} and the anisotropy factor (often defined as R100/R111).",
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Etching of silicon in alkaline solutions: A critical look at the {111} minimum. / Nijdam, A.J.; van Suchtelen, J.; Berenschot, Johan W.; Gardeniers, Johannes G.E.; Elwenspoek, Michael Curt.

In: Journal of crystal growth, Vol. 198-19, No. 198/199, 02.03.1999, p. 430-434.

Research output: Scientific - peer-reviewArticle

TY - JOUR

T1 - Etching of silicon in alkaline solutions: A critical look at the {111} minimum

AU - Nijdam,A.J.

AU - van Suchtelen,J.

AU - Berenschot,Johan W.

AU - Gardeniers,Johannes G.E.

AU - Elwenspoek,Michael Curt

PY - 1999/3/2

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N2 - Anisotropic wet-chemical etching of silicon in alkaline solutions is a key technology in the fabrication of sensors and actuators. In this technology, etching through masks is used for fast and reproducible shaping of micromechanical structures. The etch rates R{hkl} depend mainly on composition and temperature of the etchant. In a plot of etch rate versus orientation, there is always a deep, cusped minimum for the {111} orientations. We have investigated the height of the {111} etch-rate minimum, as well as the etching mechanisms that determine it. We found that in situations where masks are involved, the height of the {111} minimum can be influenced by nucleation at a silicon/mask-junction. A junction which influences etch or growth rates in this way can be recognized as a velocity source, a mathematical concept developed by us that is also applicable to dislocations and grain boundaries. The activity of a velocity source depends on the angle between the relevant {111} plane and the mask, and can thus have different values at opposite {111} sides of a thin wall etched in a micromechanical structure. This observation explains the little understood spread in published data on etch rate of {111} and the anisotropy factor (often defined as R100/R111).

AB - Anisotropic wet-chemical etching of silicon in alkaline solutions is a key technology in the fabrication of sensors and actuators. In this technology, etching through masks is used for fast and reproducible shaping of micromechanical structures. The etch rates R{hkl} depend mainly on composition and temperature of the etchant. In a plot of etch rate versus orientation, there is always a deep, cusped minimum for the {111} orientations. We have investigated the height of the {111} etch-rate minimum, as well as the etching mechanisms that determine it. We found that in situations where masks are involved, the height of the {111} minimum can be influenced by nucleation at a silicon/mask-junction. A junction which influences etch or growth rates in this way can be recognized as a velocity source, a mathematical concept developed by us that is also applicable to dislocations and grain boundaries. The activity of a velocity source depends on the angle between the relevant {111} plane and the mask, and can thus have different values at opposite {111} sides of a thin wall etched in a micromechanical structure. This observation explains the little understood spread in published data on etch rate of {111} and the anisotropy factor (often defined as R100/R111).

KW - METIS-111697

KW - IR-14610

KW - Anisotropic etching

KW - Anisotropy factor

KW - EWI-13209

KW - Surface morphology

KW - Kinematic wave theory

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