Multiple membrane structure and method of manufacture

A structure carried on a substrate, comprising:

• a first micro-machined mesh supported by the substrate;
• a second micro-machined mesh supported by the substrate and positioned above said first mesh;
• and
• a material for sealing said first and second meshes to form first and second membranes, respectively.

A microphone constructed on a substrate, comprising:

• a plurality of first membranes each formed by a micro-machined mesh supported by the substrate, each of said membranes having a first and a second position;
• a second membrane supported by the substrate and positioned above said first membrane to form a chamber between said plurality of first membranes and said second membrane;
• a pressure sensor responsive to a pressure in said chamber;
• drive electronics responsive to said pressure sensor for controlling the positions of each of said plurality of first membranes;
• and
• output electronics responsive to the positions of said plurality of first membranes.

A microphone, comprising:

• a substrate;
• a plurality of first micro-machined meshes supported by said substrate;
• a second micro-machined mesh supported by the substrate and positioned above said plurality of first meshes to form a chamber therebetween;
• a material for sealing said plurality of first meshes to form a plurality of first membranes and for sealing said second mesh to form a second membrane, each of said plurality of first membranes having first and second positions;
• a sensor responsive to said chamber;
• drive electronics responsive to said sensor for controlling the positions of each of said plurality of first membranes;
• and
• output electronics responsive to the positions of said plurality of first membranes for producing an output signal.

A method, comprising:

• fabricating a first micro-machined mesh on a substrate;
• sealing said mesh to form a membrane;
• and
• positioning a second membrane above said first membrane.

A method of fabricating stacked membranes, comprising:

• stacking alternating layers of at least two different materials on a substrate, certain of said layers being patterned;
• using a top layer as an etch mask to form an upper mesh;
• removing said top layer to expose a new top layer;
• using said new top layer to protect said upper mesh while said upper mesh is released from said substrate;
• removing said new top layer;
• using said upper mesh as an etch mask to form and release a lower mesh from said substrate;
• and
• depositing a sealant for sealing said upper and lower meshes.

A method of fabricating stacked layers, comprising:

• forming a first layer of a first material;
• forming a first layer of a second material;
• patterning said first layer of said second material to form a lower mesh;
• forming a second layer of said first material;
• forming a second layer of said second material;
• patterning said second layer of said second material to define a chamber above said lower mesh;
• forming a third layer of said first material;
• forming a third layer of said second material;
• patterning said third layer of said second material to form an upper mesh above said chamber;
• forming a fourth layer of said first material;
• forming a fourth layer of said second material;
• and
• patterning said fourth layer of said second material to act as an etch mask for forming said upper mesh.

A method, comprising:

• forming an upper micro-machined mesh on a substrate;
• releasing said upper mesh;
• forming and releasing a lower mesh under said upper mesh;
• and
• sealing said lower and upper meshes to form first and second membranes, respectively.

A method, comprising:

• sensing a pressure between an upper membrane and a plurality of lower membranes, each of said plurality of lower membranes having a micro-machined mesh;
• controlling the position of each of said plurality of lower membranes in response to said sensing;
• and
• monitoring the positions of said plurality of membranes to provide an output signal.

A method of converting sound waves to a digital signal, comprising:

• sensing a pressure in a chamber formed of an upper membrane and a plurality of lower membranes, each of said lower membranes having first and second positions, each of said lower membranes having a micro-machined mesh;
• controlling, in response to said sensing, whether each of said plurality of lower membranes is in its first or second position;
• and
• outputting a digital signal responsive to the positions of each of said plurality of lower membranes.