Cantilever pressure transducer

Claim 2

A micromechanical device comprising: a frame having an opening; at least one cantilever structure attached to said frame over a portion of a perimeter of said opening and covering a majority of said opening; and said cantilever structure including three adjacent sublayers designated first, second and third such that said second sublayer is adjacent to said first and third sublayers, said first and third sublayers formed of substantially the same first material and having about the same average stress, and said second layer formed of a second material and having a minimum stress and a maximum stress, the difference between said maximum stress and said minimum stress being less than the magnitude of the average stress of said first sublayer.

Claim 3

The device of claim 1 wherein, when said cantilever structure is in equilibrium, its deflection out of the plane of said opening is less than about 50 μm.

Claim 4

The device of claim 2 wherein said cantilever structure includes silicon nitride.

Claim 5

The device of claim 1 further including a transducer, said transducer overlapping said cantilever structure and not overlapping said substrate.

Claim 6

The device of claim 4 wherein said transducer is from the group consisting of piezoelectric, piezoresistive, capacitive, magnetostrictive and thermal transducers.

Claim 7

The device of claim 4 wherein said transducer includes a zinc oxide thin film.

Claim 8

The device of claim 1 wherein said first and third sublayers have opposite stress gradients.

Claim 9

The device of claim 7 further including a transducer, said transducer overlapping said cantilever structure and not overlapping said substrate.

Claim 10

The device of claim 8 wherein said transducer is from the group consisting of piezoelectric, piezoresistive, capacitive, magnetostrictive and thermal transducers.

Claim 11

The device of claim 8 wherein said transducer includes a zinc oxide thin film.

Claim 12

The device of claim 1 wherein an average stress of said second sublayer is less than the average stress of said first layer.

Claim 13

The device of claim 1 wherein said first and second materials include silicon.

Claim 14

The device of claim 1 wherein said first and second material include silicon nitride.

Claim 15

A micromechanical device, comprising: a substrate having first and second surfaces, and a cavity with an opening at said first surface; at least one multilayer cantilever structure attached to said first surface of said substrate over a portion of a perimeter of said opening and covering a majority of said opening; and wherein said cantilever structure includes three adjacent sublayers designated first, second and third such that said second sublayer is adjacent to said first and third sublayers, said first and third sublayers having about the same average stress, said second sublayer having a maximum stress and a minimum stress, compressive and tensile stresses considered to have opposite sign, and the magnitude of the difference between said maximum stress and said minimum stress being less than the magnitude of the average stress of said first sublayer, said first, second and third sublayers including silicon nitride.

Claim 16

A micromechanical device, comprising: a substrate having first and second surfaces, and a cavity with an opening at said first surface; at least one multilayer cantilever structure attached to said first surface of said substrate over a portion of a perimeter of said opening and covering a majority of said opening; and wherein said cantilever structure includes three adjacent sublayers designated first, second and third such that said second sublayer is adjacent to said first and third sublayers, said first and third sublayers having about the same average stress, said second sublayer having a maximum stress and a minimum stress, compressive and tensile stresses considered to have opposite sign, and the magnitude of the difference between said maximum stress and said minimum stress being less than the magnitude of the average stress of said first sublayer, said first, second and third sublayers including silicon nitride.

Claim 17

A micromechanical device comprising: a substrate having first and second surfaces, and a cavity with an opening at said first surface; at least one multilayer cantilever structure attached to said first surface of said substrate over a portion of a perimeter of said opening and covering a majority of said opening; and wherein said cantilever structure includes three adjacent sublayers designated first, second and third such that said second sublayer is adjacent to said first and third sublayers, said first and third sublayers having about the same average stress, said second sublayer having a maximum stress and a minimum stress, compressive and tensile stresses considered to have opposite sign, the magnitude of the difference between said maximum stress and said minimum stress being less than the magnitude of the average stress of said first sublayer, and said first and third sublayers having opposite stress gradients, said first, second and third sublayers including silicon nitride.

Claim 18

A micromechanical device comprising: a substrate having first and second surfaces, and a cavity with an opening at said first surface; at least one multilayer cantilever structure attached to said first surface of said substrate over a portion of a perimeter of said opening and covering a majority of said opening; and wherein said cantilever structure includes three adjacent sublayers designated first, second and third such that said second sublayer is adjacent to said first and third sublayers, said first and third sublayers having about the same average stress, said second sublayer having a maximum stress and a minimum stress, compressive and tensile stresses considered to have opposite sign, the magnitude of the difference between said maximum stress and said minimum stress being less than the magnitude of the average stress of said first sublayer, and said first and third sublayers having opposite stress gradients, said first, second and third sublayers including silicon nitride.

Claim 19

A micromechanical device, comprising: a substrate having first and second surfaces, and a cavity with an opening at said first surface; at least one multilayer cantilever structure attached to said first surface of said substrate over a portion of a perimeter of said opening and covering a majority of said opening; and wherein said cantilever structure includes three adjacent sublayers designated first, second and third such that said second sublayer is adjacent to said first and third sublayers, said first and third sublayers having about the same average stress, said second sublayer having a maximum stress and a minimum stress, compressive and tensile stresses considered to have opposite sign, the magnitude of the difference between said maximum stress and minimum stress being less than the magnitude of the average stress of said first sublayer, and an average stress of said second sublayer is less than the average stress of said first sublayer, said first, second and third sublayers including silicon nitride.

Claim 20

A micromechanical device, comprising: a substrate having first and second surfaces, and a cavity with an opening at said first surface; at least one multilayer cantilever structure attached to said first surface of said substrate over a portion of a perimeter of said opening and covering a majority of said opening; and wherein said cantilever structure includes three adjacent sublayers designated first, second and third such that said second sublayer is adjacent to said first and third sublayers, said first and third sublayers having about the same average stress, said second sublayer having a maximum stress and a minimum stress, compressive and tensile stresses considered to have opposite sign, the magnitude of the difference between said maximum stress and minimum stress being less than the magnitude of the average stress of said first sublayer, and an average stress of said second sublayer is less than the average stress of said first sublayer, said first, second and third sublayers including silicon nitride.

Claim 25

The method of claim 18 further including: growing a sacrificial backing layer before etching said slit; and etching said sacrificial backing layer after etching said slit; and wherein said sacrificial backing layer is not etched when said slit is etched.

Claim 26

The method of claim 18 wherein said second and third films are grown at the same time.

Claim 27

The method of claim 20 wherein said second and third films are grown using chemical vapor deposition.

Claim 28

The method of claim 21 wherein said second and third films include silicon nitride.

Claim 29

The method of claim 18 wherein said first film includes silicon nitride grown on a silicon dioxide-coated substrate by chemical vapor deposition in an atmosphere with a ratio of silicon atomic content to nitrogen atomic content of about 6:1.

Claim 30

The method of claim 18 further including a step of growing fourth and fifth thin films on said second and third thin films, respectively before the etching of said slit.

Claim 31

The method of claim 24 further including: growing a sacrificial backing layer before etching said slit; and etching said sacrificial backing layer after etching said slit; and wherein said sacrificial backing layer is not etched when said slit is etched.

Claim 32

The method of claim 24 wherein said fourth and fifth films are grown at the same time.

Claim 33

The method of claim 26 wherein said fourth and fifth films are grown using chemical vapor deposition.

Claim 34

The method of claim 27 wherein said fourth and fifth films include silicon dioxide.

Claim 35

The device of claim 2 wherein said frame and said cantilever structure include a polymeric material.