Microphone component and method of manufacture
An optical microphone module for installation in a microphone assembly is described. The module is manufactured by assembling a semiconductor chip, a spacer and an interferometric component in a stack with the spacer disposed between the semiconductor chip and the interferometric component. The interferometric component comprises a membrane and a substrate comprising an optical element spaced from the membrane. The semiconductor chip comprises an optoelectronic circuit including at least one photo detector and has a light source mounted thereon or integrated therein. The light source is disposed to provide light to the interferometric arrangement such that two light portions propagate via respective optical paths to create an interference pattern at the photo detector which is dependent on a position of the membrane. The stack comprises an internal cavity and at least one aperture providing a passage for air between the internal cavity and an exterior of the stack, such that the internal cavity is in fluid communication with the exterior of the stack. A first side of the membrane is in fluid communication with the exterior of the stack and a second side of the membrane is in fluid communication with the internal cavity.
1 . A method of manufacturing an optical microphone module for installation in a housing to form an optical microphone assembly, wherein the optical microphone module comprises:
an interferometric component comprising a substrate, a membrane and at least one optical element spaced from the membrane, wherein i) the at least one optical element comprises a surface of the substrate, or ii) the at least one optical element is disposed on the surface of the substrate, or iii) the at least one optical element comprises the surface of the substrate and is disposed on the surface of the substrate:
a semiconductor chip comprising an optoelectronic circuit including at least one photo detector:
a light source mounted on the semiconductor chip or integrated with the optoelectronic circuit and the at least one photo detector in the semiconductor chip; and
a spacer:
the method comprising:
assembling the semiconductor chip, the spacer and the interferometric component in a stack with the spacer disposed between the semiconductor chip and the interferometric component:
wherein the light source and the at least one photo detector have respective positions on the semiconductor chip such that after the semiconductor chip, the spacer and the interferometric component have been assembled in the stack, the light source is disposed to provide light to the interferometric component such that a first portion of said light propagates along a first optical path via said interferometric component and a second portion of said light propagates along a second different optical path via said interferometric component, wherein the second optical path is different from the first optical path, thereby giving rise to an optical path difference between the first optical path and the second optical path which depends on a distance between the membrane and the at least one optical element, and the at least one photo detector is disposed to detect at least part of an interference pattern generated by said first and second portions of light dependent on said optical path difference;
wherein the stack comprises an internal cavity and at least one aperture providing a passage for air between the internal cavity and an exterior of the stack, such that the internal cavity is in fluid communication with the exterior of the stack; and
wherein a first side of the membrane is in fluid communication with the exterior of the stack and a second side of the membrane is in fluid communication with the internal cavity.
2 . The method of claim 1 , wherein at least one of the interferometric component and the spacer has a shape that defines the internal cavity in the stack.
3 . The method of claim 1 , wherein at least one of the spacer and the interferometric component comprises the at least one aperture.
4 . The method of claim 1 , wherein the step of assembling the semiconductor chip, the spacer and the interferometric component in the stack comprises aligning at least one of the light source, the at least one photo detector, the at least one optical element or the membrane with respect to at least one other of said light source, said at least one photo detector, said at least one optical element or said membrane.
5 . The method of claim 1 , wherein the substrate of the interferometric component comprises one or more substrate apertures.
6 . The method of claim 1 , wherein the housing comprises a housing base and an enclosure, the method further comprising installing the optical microphone module in the housing to form the optical microphone assembly.
7 . The method of claim 6 , where the enclosure or the housing base comprises an acoustic port, the method further comprising sealing the enclosure or the housing base to the stack with the acoustic port aligned with the membrane.
8 . The method of claim 1 , after the semiconductor chip, the spacer and the interferometric component have been assembled in the stack, a perpendicular separation between the at least one optical element and a surface on the semiconductor chip which comprises the at least one photo detector is greater than 200 μm.
9 . The method of claim 1 , wherein the at least one optical element comprises a diffractive optical element.
10 . A method of manufacturing an optical microphone module for installation in a housing to form an optical microphone assembly, wherein the optical microphone module comprises:
an interferometric component comprising a substrate, a membrane and at least one optical element spaced from the membrane, wherein i) the at least one optical element comprises a surface of the substrate, or ii) the at least one optical element is disposed on the surface of the substrate, or iii) the at least one optical element comprises e the surface of the substrate and is disposed on the surface of the substrate:
a semiconductor chip comprising at least one photo detector and a light source, wherein the at least one photo detector and the light source are mounted on or integrated in the semiconductor chip:
a spacer; and
one or more optical components provided in or on the spacer:
the method comprising:
assembling the semiconductor chip, the spacer and the interferometric component in a stack with the spacer disposed between the semiconductor chip and the interferometric component:
wherein the light source and the at least one photo detector have respective positions on the semiconductor chip such that after the semiconductor chip, the spacer and the interferometric component have been assembled in the stack, the light source is disposed to provide light to the interferometric component such that a first portion of said light propagates along a first optical path via said interferometric component and a second portion of said light propagates along a second optical path via said interferometric component, wherein the second optical path is different from the first optical path, thereby giving rise to an optical path difference between the first optical path and the second optical path which depends on a distance between the membrane and the at least one optical element, and the at least one photo detector is disposed to detect at least part of an interference pattern generated by said first and second portions of light dependent on said optical path difference:
wherein the stack comprises an internal cavity and at least one aperture providing a passage for air between the internal cavity and an exterior of the stack, such that the internal cavity is in fluid communication with the exterior of the stack; and
wherein a first side of the membrane is in fluid communication with the exterior of the stack and a second side of the membrane is in fluid communication with the internal cavity.
11 . The method of claim 10 , wherein the spacer comprises a supporting structure suspended in a region between the semiconductor chip and the interferometric component, wherein the one or more optical components are provided in or on the supporting structure.
12 . An optical microphone module for installation in a housing to form an optical microphone assembly, the optical microphone module comprising:
an interferometric component comprising a substrate, a membrane and at least one optical element spaced from the membrane, wherein i) the at least one optical element comprises a surface of the substrate, or ii) the at least one optical element is disposed on the surface of the substrate, or iii) the at least one optical element comprises the surface of the substrate and is disposed on the surface of the substrate:
a semiconductor chip comprising an optoelectronic circuit including at least one photo detector:
a light source mounted on the semiconductor chip or integrated with the optoelectronic circuit and the at least one photo detector in the semiconductor chip; and
a spacer:
wherein the semiconductor chip, the spacer and the interferometric component are assembled in a stack with the spacer disposed between the semiconductor chip and the interferometric component:
wherein the light source is arranged to provide light to the interferometric component such that a first portion of said light propagates along a first optical path via said interferometric component and a second portion of said light propagates along a second optical path via said interferometric component, wherein the second optical path is different from the first optical path, thereby giving rise to an optical path difference between the first optical path and the second optical path which depends on a distance between the membrane and the at least one optical element, and wherein the at least one photo detector is arranged to detect at least part of an interference pattern generated by said first and second portions of light dependent on said optical path difference:
wherein the stack comprises an internal cavity and at least one aperture providing a passage for air between the internal cavity and an exterior of the stack, such that the internal cavity is in fluid communication with the exterior of the stack; and
wherein a first side of the membrane is in fluid communication with the exterior of the stack and a second side of the membrane is in fluid communication with the internal cavity.
13 . The optical microphone module of claim 12 , wherein at least one of the interferometric component and the spacer has a shape that defines the internal cavity in the stack.
14 . The optical microphone module of claim 12 , wherein at least one of the spacer and the interferometric component comprises the at least one aperture.
15 . The optical microphone module of claim 12 , wherein the interferometric component comprises one or more substrate apertures.
16 . The optical microphone module of claim 12 , wherein a perpendicular separation between the at least one optical element and a surface on the semiconductor chip which comprises the at least one photo detector is greater than 200 μm.
17 . The optical microphone module of claim 12 , wherein the at least on optical element comprises a diffractive optical element.
18 . The optical microphone module of claim 12 , wherein one or more optical components are provided in or on the spacer.
19 . The optical microphone module of claim 18 , wherein the spacer comprises a supporting structure suspended in a region between the semiconductor chip and the interferometric component, wherein the one or more optical components are provided in or on the supporting structure.
20 . An optical microphone assembly or host device comprising the optical microphone module of claim 12 installed therein or thereon.