A method of forming a MEMS microphone, the method comprising: providing an SOI wafer having a top layer; etching trenches in the top layer of the SOI wafer; forming a sacrificial material (24, 26) on the top layer of the SOI wafer and adding sacrificial oxide to the walls of the trenches; forming a diaphragm on the sacrificial material; forming a hole through the diaphragm; adding wet etch resistant material layer completely covering the diaphragm; exposing the hole in the diaphragm; forming a channel through the sacrificial material, the hole and channel being in fluid communication, the channel exposing a bottom surface of the diaphragm and a top surface of the top layer of the SOI wafer; adding wet etch resistant material having a first portion within the channel contact with the top layer of the SOI wafer and the bottom surface of the diaphragm around the diaphragm hole, and having a second portion contiguous with the first portion that is external to the channel and substantially completely fills the hole through the diaphragm; forming a backside cavity on the bottom side of the SOI wafer, exposing a portion of oxide layer within the SOI wafer; removing a portion of the exposed oxide layer within the SOI wafer to expose part of the sacrificial layer (24, 26) formed in said trenches; removing at least a portion of the sacrificial material with a dry etch process through the backside cavity before removing any of the wet etch resistant material, wherein the wet etch resistant material layer completely covering the diaphragm is not removed before adding wet etch resistant material having the first portion within the channel; and releasing the diaphragm by removing the wet etch resistant material after said removing at least a portion of the sacrificial material. providing an SOI wafer having a top layer; etching trenches in the top layer of the SOI wafer; forming a sacrificial material (24, 26) on the top layer of the SOI wafer and adding sacrificial oxide to the walls of the trenches; forming a diaphragm on the sacrificial material; forming a hole through the diaphragm; adding wet etch resistant material layer completely covering the diaphragm; exposing the hole in the diaphragm; forming a channel through the sacrificial material, the hole and channel being in fluid communication, the channel exposing a bottom surface of the diaphragm and a top surface of the top layer of the SOI wafer; adding wet etch resistant material having a first portion within the channel contact with the top layer of the SOI wafer and the bottom surface of the diaphragm around the diaphragm hole, and having a second portion contiguous with the first portion that is external to the channel and substantially completely fills the hole through the diaphragm; forming a backside cavity on the bottom side of the SOI wafer, exposing a portion of oxide layer within the SOI wafer; removing a portion of the exposed oxide layer within the SOI wafer to expose part of the sacrificial layer (24, 26) formed in said trenches; removing at least a portion of the sacrificial material with a dry etch process through the backside cavity before removing any of the wet etch resistant material, wherein the wet etch resistant material layer completely covering the diaphragm is not removed before adding wet etch resistant material having the first portion within the channel; and releasing the diaphragm by removing the wet etch resistant material after said removing at least a portion of the sacrificial material.