### Abstract

Original language | Undefined |
---|---|

Pages (from-to) | 430-434 |

Number of pages | 5 |

Journal | Journal of crystal growth |

Volume | 198-19 |

Issue number | 198/199 |

DOIs | |

State | Published - 2 Mar 1999 |

### Fingerprint

### Keywords

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

### Cite this

*Journal of crystal growth*,

*198-19*(198/199), 430-434. DOI: 10.1016/S0022-0248(98)01032-X

}

*Journal of crystal growth*, vol 198-19, no. 198/199, pp. 430-434. DOI: 10.1016/S0022-0248(98)01032-X

**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.

Research output: Scientific - peer-review › Article

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

Y1 - 1999/3/2

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

KW - Silicon

U2 - 10.1016/S0022-0248(98)01032-X

DO - 10.1016/S0022-0248(98)01032-X

M3 - Article

VL - 198-19

SP - 430

EP - 434

JO - Journal of crystal growth

T2 - Journal of crystal growth

JF - Journal of crystal growth

SN - 0022-0248

IS - 198/199

ER -