Double notch etch to reduce under cut of micro electro-mechanical system (mems) devices

A method for reducing variability of a mechanical beam in a microelectromechanical (MEM) device comprising:

• forming a beam structure on a substrate, wherein the beam structure comprises
• a first notch at a first portion of the beam structure,
• a second notch at a second portion of the beam structure, and
• a body positioned between the first notch and the second notch;
• and
• releasing the beam structure from the substrate using an etching process that facilitates reduced variability of one or more of
• a mechanical stiffness of the mechanical beam,
• a height of the mechanical beam, and
• a performance characteristic of the mechanical beam,
• wherein the reduced variability is compared to a baseline variability without the second notch.

A method for fabricating a mechanical beam in a microelectromechanical (MEM) device comprising:

• depositing a masking layer on a first side of a substrate;
• etching a first notch on the first side of the substrate;
• forming a beam structure on the substrate, wherein a first portion of the beam structure is coupled to the first notch;
• etching a second notch at a second portion of the beam structure;
• depositing an oxide layer on the beam structure, the masking layer, and the substrate;
• etching a horizontal surface of the oxide layer at the masking layer and the substrate;
• and
• releasing the mechanical beam from the substrate, wherein the mechanical beam comprises the beam structure, the oxide layer, and the masking layer.