MEMS process and device

摘要

A method of fabricating a micro-electrical-mechanical system (MEMS) transducer comprises the steps of forming a membrane on a substrate, and forming a back-volume in the substrate. The step of forming a back-volume in the substrate comprises the steps of forming a first back-volume portion and a second back-volume portion, the first back-volume portion being separated from the second back-volume portion by a step in a sidewall of the back-volume. The cross-sectional area of the second back-volume portion can be made greater than the cross-sectional area of the membrane, thereby enabling the back-volume to be increased without being constrained by the cross-sectional area of the membrane. The back-volume may comprise a third back-volume portion. The third back-volume portion enables the effective diameter of the membrane to be formed more accurately.

主权项

1. A micro-electrical-mechanical system (MEMS) capacitive microphone comprising:
a substrate; a membrane formed relative to a first side of the substrate; and a back-volume formed in the substrate relative to a second side of the substrate; wherein the back-volume comprises a first back-volume portion and a second back-volume portion having a boundary therebetween defined by a discontinuity in a sidewall of the substrate; and wherein the cross sectional area of the second back-volume portion is greater than the cross sectional area of the first back-volume portion.