Techniques of anisotropic wet etch micromachining for comb drive transducers and resonance frequency reduction

US7604749B2 · kind B2 · utility

Inventor

• Omer Cohen · Yoqneam Illit, IL

Key dates

• Filing date: Dec 21, 2006
• Grant date: Oct 20, 2009
• Expiry date: Dec 25, 2026

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B81C2201/0133
• WIPO field: Micro-structural and nano-technology
• WIPO sector: Chemistry

Abstract

Wet anisotropic etching techniques are well known micromachining apparatus in MEMS technology. The wet anisotropic etchant etch some of the material crystal planes faster than the other. For example the (001) planes are etched much faster than the (111) planes. The final shape is dependent upon the etch mask and the crystal planes orientation. A technique is described hereafter where the nature of the wet anisotropic etch process is used for fabrication of electrostatic transducers and in particular electrostatic comb drive actuators and sensors. Using the same anisotropic wet etching technique it is possible to reduce the cross section of suspensions and thus to soften a spring or to change the resonance frequency of mechanical resonators. Final cross section is dependent of the etching time. Under the anisotropic wet etching the cross section of the suspensions is changed rapidly.