PATENT DOCUMENT

Publication Number: US-9404860-B2
Application Number: US-201414330723-A
Country: US
Kind Code: B2

Title: Micro-electro-mechanical system optical sensor with tilt plates

Abstract:
A micro-electro-mechanical system (MEMS) optical sensor, method of detecting sound using the MEMS optical sensor and method of manufacturing. The MEMS optical sensor including a substrate having a base portion and a vertically extending support portion. The sensor further including a top plate having a compliant membrane configured to vibrate in response to acoustic waves, the top plate connected to the support portion and having a reflective surface. The sensor also includes a back plate connected to the support portion, the back plate having a grating portion positioned below the reflective surface portion and a base plate connected to the support portion at a position below the back plate. A light emitter, a light detector and circuitry operable to tilt the top plate and the back plate with respect to the base plate so as to direct the reflected laser light toward the light detector are further provided.

Claims:
What is claimed is: 
     
       1. A micro-electro-mechanical system (MEMS) optical sensor comprising:
 a substrate having a base portion and a vertically extending support portion; 
 a top plate having a compliant membrane configured to vibrate in response to acoustic waves, the top plate connected to the support portion so as to tilt, the compliant membrane having a reflective surface portion; 
 a back plate connected to the support portion so as to tilt, and being spaced apart from the compliant membrane, the back plate having a grating portion positioned below the reflective surface portion; 
 a base plate connected to the support portion at a position below the back plate; 
 a light emitter positioned on the base portion below the back plate and configured to transmit a laser light through the grating portion and toward the reflective surface portion of the compliant membrane; 
 a light detector positioned on the base portion below the back plate and configured to detect a diffracted pattern of the laser light after reflection from the reflective surface; and 
 circuitry operable to apply a voltage to one or more of the back plate and the top plate, relative to the base plate, that causes tilting of the top plate and the back plate with respect to the base plate. 
 
     
     
       2. The optical sensor of  claim 1  wherein the compliant membrane is a MEMS microphone diaphragm. 
     
     
       3. The optical sensor of  claim 1  wherein the MEMS optical sensor is an optical microphone. 
     
     
       4. The optical sensor of  claim 1  wherein each of the top plate and the back plate comprise a first end movably connected to the support portion and a second free end. 
     
     
       5. The optical sensor of  claim 1  wherein tilting the top plate and the back plate with respect to the base plate comprises moving the top plate and the back plate while the base plate remains stationary. 
     
     
       6. The optical sensor of  claim 1  wherein the tilt of the top plate and the back plate with respect to the base plate is at an acute angle. 
     
     
       7. The optical sensor of  claim 1  wherein each of the top plate and the back plate are connected to the vertically extending support portion by a spring. 
     
     
       8. The optical sensor of  claim 1  wherein the top plate comprises a frame and spokes for suspending the compliant membrane within the frame. 
     
     
       9. The optical sensor of  claim 1  wherein posts are positioned between the top plate and the back plate to define a controlled minimal stress region of operation for the top plate. 
     
     
       10. The optical sensor of  claim 1  wherein the top plate and the back plate are tilted toward the base plate. 
     
     
       11. The optical sensor of  claim 1  wherein application of a current by the circuitry produces an electrostatic force operable to draw the back plate and the top plate toward the base plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The application claims the benefit of the earlier filing date of co-pending U.S. Provisional Patent Application No. 61/991,067, filed May 9, 2014 and incorporated herein by reference. 
    
    
     FIELD 
     An embodiment of the invention is directed to a micro-electro-mechanical system (MEMS) device having a tilted plate, more specifically, a MEMS optical microphone having a tilted compliant membrane and back plate. Other embodiments are also described and claimed. 
     BACKGROUND 
     MEMS devices generally range in size from about 20 micrometers to about 1 millimeter and are made up of a number of even smaller components which can be formed in layers on a substrate using various MEMS processing techniques (e.g. deposition processes, patterning, lithography, etching, etc.). MEMS devices can be processed for many different applications, for example, they may be sensors or actuators. One such type of MEMS sensor is a laser microphone. A MEMS laser, or optical, microphone refers to a microphone which uses a laser beam to detect sound vibrations of an associated diaphragm. The microphone may include two essentially flat, horizontally arranged, surfaces. One of the surfaces may be a diaphragm, which can vibrate in response to sound waves, and the other surface may be a substantially stiff structure having a grating. A light emitter and a light detector may be associated with a substrate positioned below the flat surfaces. The light emitter may be a laser (e.g. a vertical cavity surface emitting laser (VCSEL)) configured to direct a light beam toward a reflective portion of the diaphragm. The light beam is diffracted by the grating and reflected off of the reflective portion back to the light detector. The light detector detects the interference pattern created by the diffracted light rays and converts the light into an electrical signal, which corresponds to an acoustic vibration of the diaphragm, which in turn provides an indication of sound. 
     SUMMARY 
     An embodiment of the invention is directed to a MEMS sensor such as a very high SNR (signal-to-noise ratio) laser (or optical) MEMS microphone having one or more layers, plates or membranes which can be tilted to modify an alignment between a light source (which is stationary) and a reflective layer (e.g. a diaphragm having a reflective portion). For proper operation of an optical microphone, the light beam from the light source should be properly aligned with a reflective portion of the diaphragm. Proper alignment, however, can be difficult in MEMS type structures in which it is not feasible to mass manufacture tilted surfaces and layers. The MEMS sensor can be formed by MEMS processing techniques suitable for forming one or more plates (e.g. electrodes) which can be tilted. 
     An embodiment of the invention solves the alignment problem in an optical microphone by allowing for the manufacture of a MEMS structure, for example, an optical MEMS microphone, having a compliant membrane (e.g. diaphragm) with a reflective surface and a back plate having a grating, both of which can be tilted, with respect to a light source, by applying a voltage. Representatively, the compliant membrane may be formed over a substrate and may have a reflective surface portion. The compliant membrane may have a first end movably connected to a vertically extending portion of the substrate, and a second, free end. The back plate may be positioned below, and substantially parallel to, the compliant membrane and may include a grating portion. The back plate may have a first end movably connected to the vertically extending portion of the substrate and a second, free end. A base plate extending substantially horizontally from a portion of the vertically extending portion of the substrate and spaced a distance below the free ends of the compliant membrane and back plate is further provided. A light source (e.g. a vertical-cavity surface-emitting laser (VCSEL)), positioned on the substrate, below the compliant membrane and back plate, is directed toward the grating of the back plate and reflective surface portion of the compliant membrane. A light detector may further be positioned on the substrate to detect a pattern of light reflected off of the compliant membrane and back plate grating (i.e. an interference pattern). The pattern represents a displacement of the compliant membrane caused by sound pressure waves, and therefore can be used to provide an indication of sound. In this aspect, the MEMS device uses a diffraction based optical interferometer method to provide an indication of sound. Circuitry may further be connected to the compliant membrane, the back plate, the base plate, the light emitter and/or the light detector. 
     During operation, application of a voltage by the circuitry causes electrostatic forces between the compliant membrane, the back plate and the base plate to tilt the compliant membrane and the back plate toward the base plate (which is stationary). In one embodiment, in the resting position (i.e. no voltage) the compliant membrane, the back plate and the base plate are substantially parallel to one another, in what may be described as a “horizontal” position. In the active position (i.e. voltage is applied), the free end of the back plate moves toward the base plate to tilt the back plate and set the tilt angle and the free end of the compliant membrane moves toward the back plate to tilt the compliant membrane. The tilt angle may be an acute angle, for example, less than 4 degrees, or for example, 3 degrees or less. In some embodiments, the tilt angle is a predetermined, set, angle such that the back plate and compliant membrane are either tilted at the set tilt angle or they are not tilted and in the horizontal position. In other embodiments, the tilt angle can vary depending upon the voltage applied. In other words, the application of a smaller voltage will result in a different tilt angle (e.g. smaller tilt angle) then when a larger voltage is applied (e.g. larger tilt angle). Spacers or posts may further be provided between the compliant membrane, the back plate and the support arm to avoid stiction and define a controlled minimal stress region of operation for the compliant membrane. 
     A process for manufacturing a MEMS optical microphone may include providing a substrate and forming a base plate layer over the substrate. A back plate layer may be formed over the base plate layer and a compliant membrane layer may be formed over the back plate layer. A light emitter and a light detector may be connected to the substrate. In addition, directional circuitry may be connected to the base plate layer, the back plate layer and the compliant membrane layer. The circuitry is operable to cause the back plate layer and the compliant membrane layer to tilt with respect to the base plate layer when a voltage is applied so as to modify an alignment between a reflective portion of the compliant membrane layer and the light source and direct the reflected light toward the light detector. In some embodiments, prior to forming the base plate layer, the back plate layer and the compliant membrane layer, a sacrificial layer is formed between each layer to define a gap between each of the layers, and then subsequently removed. Each of the layers may be formed using MEMS processing techniques. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. 
         FIG. 1A  illustrates a cross-sectional side view of one embodiment of a MEMS device. 
         FIG. 1B  illustrates the MEMS device of  FIG. 1A  in a tilted configuration. 
         FIG. 2A  illustrates a cross-sectional side view of one embodiment of a MEMS optical microphone. 
         FIG. 2B  illustrates the optical microphone of  FIG. 2A  in a tilted configuration. 
         FIG. 3  illustrates a top view of the compliant membrane of the optical microphone of  FIG. 2A . 
         FIG. 4  illustrates a bottom view of the compliant membrane of  FIG. 3 . 
         FIG. 5  illustrates a top view of a back plate of the optical microphone of  FIG. 2A . 
         FIG. 6  illustrates a bottom view of the back plate of  FIG. 5 . 
         FIG. 7A  illustrates one embodiment of a processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7B  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7C  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7D  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7E  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7F  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7G  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7H  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7I  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 7J  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A . 
         FIG. 8  illustrates one embodiment of a simplified schematic view of one embodiment of an electronic device in which the optical microphone may be implemented. 
         FIG. 9  illustrates a block diagram of some of the constituent components of an embodiment of an electronic device in which an embodiment of the invention may be implemented. 
     
    
    
     DETAILED DESCRIPTION 
     In this section we shall explain several preferred embodiments of this invention with reference to the appended drawings. Whenever the shapes, relative positions and other aspects of the parts described in the embodiments are not clearly defined, the scope of the invention is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments of the invention may be practiced without these details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this description. 
       FIG. 1A  illustrates a cross-sectional side view of one embodiment of a MEMS device. MEMS device  100  may, in some embodiments, be any type of MEMS sensor that can benefit from being able to tilt one or more plates or layers within the sensor as described herein. For example, MEMS device  100  may be an optical microphone, an inertial sensor, an accelerometer, a gyrometer or the like. Representatively, in one embodiment, device  100  includes a top plate  102 , a middle plate  104  and a bottom plate  106 . Each of top plate  102 , middle plate  104  and bottom plate  106  may be parallel to one another in one state, and extend horizontally from vertically extending support members  108 A or  108 B of substrate  110  (i.e. top plate  102 , middle plate  104  and bottom plate  106  are perpendicular to support members  108 A- 108 B). In one embodiment, vertically extending support members  108 A and  108 B may be sidewalls of a cavity  140  which is pre-formed within substrate  110  before each of top plate  102 , middle plate  104  and bottom plate  106  are formed using MEMS processing techniques (e.g. deposition processes, patterning, lithography, etching, etc.). 
     In one embodiment, top plate  102  is attached at one end  128  to vertically extending support member  108 B by a spring  112 , or other similar structure that allows for movement of top plate  102  with respect to support member  108 B. The other end of top plate  102  is a free end  130  that is not directly connected to another structure (e.g., the free end  130  is not connected to support member  108 A). Similarly, middle plate  104  is attached at one end  132  to support member  108 B by a spring  114  and the other end is a free end  134  that is not directly connected to another structure. Top plate  102  and middle plate  104  may have a similar length, which is slightly less than the distance between support member  108 A and  108 B. Middle plate  104  is spaced a distance below top plate  102  by spacers  116 A and  116 B. Spacers  116 A and  116 B may be formed on a bottom side of top plate  102 , or a top side of middle plate  104 , such that they space one plate from the other. 
     Bottom plate  106  extends from vertically extending support member  108 A, in a direction toward support member  108 B. Middle plate  104  is spaced a distance from bottom plate  106  by spacer  136 . Unlike top plate  102  and middle plate  104 , bottom plate  106  is a stationary structure which is fixedly attached to support member  108 B. In some embodiments, bottom plate  106  has a length which is shorter than a length of top plate  102  and middle plate  104 . For example, bottom plate  106  extends a distance from support member  108 A such that it is beneath the free ends  130 ,  134  of top plate  102  and middle plate  104 , but less than the entire length of top plate  102  and bottom plate  104 . In other embodiments, bottom plate  106  may extend from support member  108 B, in a direction of support member  108 A, and in some cases, extend all the way to support member  108 A such that both ends are fixed to respective support members  108 A- 108 B. In each embodiment, it is important that bottom plate  106  have a length sufficient provide a fixed support surface below middle plate  104  for tilting of middle plate  104 . 
     Device  100  may further include a circuit  124  (e.g. an application specific integrated circuit (ASIC)) electrically connected to top plate  102 , middle plate  104  and bottom plate  106  by wiring  118 ,  120  and  122 , respectively. Wiring  118 ,  120  and  122  may run through substrate  110  and support members  108 A- 108 B to the respective plates  102 ,  104  and  106 . In one embodiment, circuit  124  may be configured to receive power from an external source and apply a voltage to one or more of top plate  102 , middle plate  104  and bottom plate  106 . The application of a voltage to one or more of top plate  102 , middle plate  104  and bottom plate  106  can be used to tilt the plates from the resting, and in this example horizontal, position shown in  FIG. 1A . 
       FIG. 1B  illustrates the MEMS device of  FIG. 1A  in a tilted configuration. Representatively, the application of the voltage to one or more of top plate  102 , middle plate  104  and bottom plate  106  through circuit  124  creates electrostatic forces between each plate which cause the plates to be drawn toward one another. In other words, top plate  102 , middle plate  104  and bottom plate  106  act as electrodes which are electrically isolated from one another by spacers  116 A,  116 B,  136  such that capacitors are formed between each of the plates. Therefore, when the appropriate voltage is applied to each of top plate  102 , middle plate  104  and bottom plate  106 , the resulting electrostatic forces cause them to become clamped together. In one embodiment, the voltage can be applied as a direct current (DC) voltage. Alternatively, the voltage can be an alternating current (AC) voltage. Since end  128  of top plate  102  and end  132  of middle plate  104  are connected to support member  108 B by springs  112  and  114 , respectively, the greatest degree of movement occurs at free ends  130 ,  134 . Still further, since bottom plate  106  is stationary, free end  130  of top plate  102  and free end  134  of middle plate  104  move toward bottom plate  106  resulting in top plate  102  and middle plate  104  having a tilted configuration in which ends  128 ,  132  are higher than free ends  130 ,  134 . 
     Representatively, when the appropriate voltage is applied to each of top plate  102 , middle plate  104  and bottom plate  106 , the free end  134  of the middle plate  104  moves toward the bottom plate  106  (which is stationary) to tilt the middle plate  104  and set the tilt angle  126 . In addition, the free end  130  of top plate  102  moves toward middle plate  104  to tilt the top plate  102 . In this aspect, top plate  102  and middle plate  104  can be accurately tilted to an optimal and fine tuned tilt angle  126 , which provides a desired device performance (e.g. directs light reflected off the plates toward a detector). For example, in one embodiment, the angle  126  may be an acute angle, for example, less than 4 degrees, for example, 3 degrees or less. It is further to be understood that spacers  116 A,  116 B and  136  are dimensioned to maintain an even space or gap between top plate  102 , middle plate  104  and bottom plate  106  so that stiction between the plates is avoided and a controlled minimal stress region of operation between top plate  102  and middle plate  104  can be maintained. In this aspect, a device which is formed using MEMS processing techniques is provided which includes components (e.g. plates) that can be tilted from an otherwise horizontal orientation typically found in MEMS devices. 
       FIG. 2A  illustrates a cross-sectional side view of another embodiment of a MEMS device. In this embodiment, the MEMS device is a MEMS optical microphone  200 . In this aspect, since the MEMS device is an optical microphone, each of the previously discussed plates  102 ,  104  and  106 , although operable in the manner previously discussed, are manufactured using MEMS processing techniques to carry out the functions of an optical microphone. Representatively, microphone  200  may include a top plate such as compliant membrane  202 , a middle plate such as back plate  204 , a bottom plate such as base plate  206 , an emitter  260  and a detector  262 . Each of compliant membrane  202 , back plate  204 , base plate  206 , and in some cases emitter  260  and detector  262 , may be built on substrate  210  using MEMS processing techniques. Substrate  210  may be mounted within a frame or enclosure  240 . Enclosure  240  may include an acoustic port  242  through which sound (S) (also referred to as acoustic waves) can travel into microphone  200 . Although acoustic port  242  is illustrated along a top side of enclosure  240 , it could also be along a bottom side or side wall of enclosure  240  (while still allowing the acoustic waves to reach the compliant membrane  202 ) and therefore is not limited to the illustrated location. 
     Compliant membrane  202  may be configured to vibrate in response to sound (S) (acoustic waves) entering enclosure  240  through acoustic port  242 . In this aspect, compliant membrane  202  may also be referred to as a diaphragm. Compliant membrane  202  may be made of any material and have any dimensions suitable to provide a semi-rigid or compliant membrane that vibrates in response to sound waves, for example, polysilicon. In addition, compliant membrane  202  may be made of, or have a material integrated therein, that allows for compliant membrane  202  to function as an electrode. In some embodiments, a center portion  270  of compliant membrane  202  may be considered the portion that vibrates while the outer portions primarily serve as a rigid frame to support center portion  270  as will be discussed in more detail in reference to  FIG. 3 . In this aspect, the center portion  270  may be more compliant than the outer portions. 
     In addition, a reflective surface  272  may be formed on a side of center portion  270  facing emitter  260  and detector  262  such that a vibration of center portion  270  can be detected by reflecting a light emitted by emitter  260  toward detector  262 . In some embodiments, the center portion  270  is made of a reflective material (e.g. metallic foil) while in other embodiments, the reflective surface  272  is formed by application of a coating (e.g. metal coating such as gold) to center portion  270 . Although reflective surface  272  is shown positioned only within center portion  270 , it is contemplated that the reflective surface may extend beyond center portion, for example, to the ends  230 ,  228  of compliant membrane  202 . Compliant membrane  202 , including center portion  270  and reflective surface  272 , may be built upon substrate  210  using MEMS processing techniques (e.g. deposition processes, patterning, lithography, etching, etc.). 
     Back plate  204  may be a substantially rigid plate positioned between compliant membrane  202  and emitter  260  and detector  262 . For example, back plate  204  may be made of a thick and stiff silicon plate. In addition, back plate  204  may be made of, or have a material integrated therein, that allows for back plate  204  to function as an electrode that can be tilted as described herein. Back plate  204  may include a grating  280  aligned with emitter  260  and detector  262  such that light directed toward reflective surface  272  and light reflected from reflective surface  272  passes through grating  280 . Grating  280  is dimensioned to form an interference pattern which can be detected by detector  262  and used as an indicator of a movement of compliant membrane  202 . Since the pattern represents a displacement of the compliant membrane  202 , it can be used to provide an indication of sound using a diffraction based optical interferometer method or any other optical interferometric method. Representatively, in some embodiments, grating  280  may also include a reflective coating  282  to facilitate formation of the interference pattern. Back plate  204 , including grating  280 , may be built upon substrate  210  using MEMS processing techniques (e.g. deposition processes, patterning, lithography, etching, etc.). 
     Base plate  206  may be a substantially rigid plate positioned between back plate  204  and emitter  260  and detector  262 . Base plate  206  may be a fixed structure that is built upon substrate  210  using MEMS processing techniques (e.g. deposition processes, patterning, lithography, etching, etc.). In this aspect, base plate may be made of a similar material, or different material, as back plate  204 , for example, a silicon material. 
     In one embodiment, in their untilted state, each of compliant membrane  202 , back plate  204  and base plate  206  are parallel to one another and extend in a direction perpendicular to vertically extending support members  208 A or  208 B (e.g. horizontally). Vertically extending support members  208 A and  208 B may be members which extend in a direction perpendicular to a horizontal base portion  250  of substrate  210 . Vertically extending support members  208 A and  208 B may be pre-formed portions of substrate  210  (i.e. sidewalls of a cavity  290  formed within substrate  210 ) or formed on top of substrate  210  using MEMS techniques. 
     Compliant membrane  202  is attached at one end  228  to vertically extending support member  208 B by a spring  212 , or other similar structure that allows for a pivot or hinge type movement of compliant membrane  202  with respect to support member  208 B. Representatively, spring  212  may be a tension/extension spring, a flat spring, a corrugated structure, or an arm member which has some degree of elasticity to allow for compliant membrane  202  to be tilted without interfering with a vibration of compliant membrane  202  in response to sound waves. The other end of compliant membrane  202  is a free end  230  that is not directly connected to another structure (e.g., the free end is not connected to support member  208 A). In this aspect, free end  230  is free to move up or down while a vertical position of end  228  along support member  208 B remains substantially the same. Compliant membrane  202  may have a length which is slightly less than a distance between support member  208 A and  208 B such that it can be tilted between members  208 A and  208 B. 
     Back plate  204  is attached at one end  232  to support member  208 B. Back plate  204  may be attached to support member  208 B at a position below end  228  of compliant membrane  202  such that back plate  204  is between compliant membrane  202  and base plate  206 . End  232  of back plate  204  may be attached to support member  208 B by a spring  214 . Spring  214  may be similar to spring  212 . The other end of back plate  204  is a free end  234  that is not directly connected to another structure (e.g. not directly connected to support member  208 B). In this aspect, free end  234  is free to move up or down while a vertical position of end  232  along support member  208 B remains substantially the same such that back plate  204  can be tilted similar to compliant membrane  202 . Back plate  204  may have a length which is slightly less than a distance between support member  208 A and  208 B such that it can be tilted between members  208 A and  208 B. 
     Compliant membrane  202  is spaced a distance from back plate  204  by spacers  216 A and  216 B. Spacers  216 A and  216 B may be attached to a bottom surface of compliant membrane  202  or a top surface of back plate  204 . Spacers  216 A and  216 B may be of a dimension and material which allows them to both mechanically and electrically isolate compliant membrane  202  from back plate  204 . Representatively, spacers  216 A and  216 B may be made of an insulating material, for example, porcelain (ceramic), glass, mica, plastics, and the oxides of various metals. 
     Base plate  206  extends from vertically extending support member  208 A, in a direction toward support member  208 B. Base plate  206  may be at a position along support member  208 A which is below back plate  204  such that base plate  206  is between back plate  204  and substrate  210 . Base plate  206  is positioned a distance from back plate  204  by spacer  236 . Spacer  236  may be attached to one of a bottom side of back plate  204  or a top side of base plate  206  and be of a dimension and material such that it both mechanically and electrically isolates back plate  204  from base plate  206 . Representatively, spacer  236  may be made of an insulating material (e.g., porcelain (ceramic), glass, mica, plastics, and the oxides of various metals). 
     Unlike compliant membrane  202  and back plate  204 , base plate  206  is a stationary structure which is fixedly attached to support member  208 B. In some embodiments, base plate  206  has a length which is shorter than a length of compliant membrane  202  and back plate  204 . For example, base plate  206  extends a distance from support member  208 A such that it is beneath the free ends  230 ,  234  of compliant membrane  202  and back plate  204 , but not beneath the entire length of compliant membrane  202  and base plate  204 . In other embodiments, base plate  206  extends from support member  208 A to support member  208 B such that it extends the entire distance between support members  208 A- 208 B and, in some cases, is fixed at both ends to the respective support member  208 A- 208 B. 
     Device  200  may further include a circuit  224  (e.g. an application specific integrated circuit (ASIC)) attached to compliant membrane  202 , back plate  204  and base plate  206  by wiring  218 ,  220  and  222 , respectively. Wiring  218 ,  220  and  222  may run through substrate  210  and support members  208 A- 208 B to the respective one of membrane  202 , back plate  204  and base plate  206 . In one embodiment, the circuit  224  may be configured to receive power from an external source and apply a voltage to one or more of compliant membrane  202 , back plate  204  and base plate  206 . The application of a voltage to one or more of compliant membrane  202 , back plate  204  and base plate  206  can be used to tilt the plates from the otherwise horizontal position shown in  FIG. 2A . When the voltage is removed, compliant membrane  202 , back plate  204  and base plate  206  may return to the resting position (i.e. horizontal position). 
     In addition, circuit  224  may be connected to emitter  260  and detector  262  by wiring  284 ,  286 , respectively. Wiring  284 ,  286  may run through substrate  210  and support members  208 A- 208 B to emitter  260  and/or detector  262 . In this aspect, circuit  224  may receive power from an external source and provide power to emitter  260  and/or detector  262 . In some embodiments, emitter  260  may be a light source such as a VCSEL that is electrically connected to substrate  210 . Emitter  260  may be configured to emit a laser light (or beam) in the direction of grating  280  and reflector  282 , for detection by detector  262 . Detector  262  may, in some embodiments, be a photo detector configured to detect a reflected light (or beam) generated by emitter  260 . The emitter  260  (e.g. VCSEL) and detector  262  (e.g. photo detector) can be off the shelf commercially available parts or custom built for a specific implementation. 
     Each of compliant membrane  202 , back plate  204  and base plate  206  are parallel to one another and substantially planar structures which are manufactured in a horizontal configuration. Emitter  260  is directly below compliant membrane  202  and back plate  204  such that light emitted from emitter  260  is directed “straight on” toward compliant membrane  202  and back plate  204 . In this configuration, however, the light will reflect off of reflective surface  272  of compliant membrane  202  back to emitter  260 , not detector  262 , as illustrated by dashed arrow  288 . In this aspect, to properly align the reflected light and direct the light to detector  262 , compliant membrane  202  and back plate  204  are tilted as illustrated in  FIG. 2B . It is noted that the light is directed by tilting only compliant membrane  202  and back plate  204 , not emitter  260 , detector  262  and/or substrate  210  thus providing a microphone which can be mass produced using MEMS processing techniques and without adding tolerances associated with, for example, positioning emitter  260  and/or detector  262  at an angle. 
     As can be seen from  FIG. 2B , tilting of compliant membrane  202  and base plate  204 , causes reflected light  288  to be directed toward detector  262 . Representatively, during operation, a voltage is applied to compliant membrane  202 , back plate  204  and base plate  206  through circuit  224 . The voltage creates electrostatic forces between each plate causing them to be drawn toward one another. In other words, compliant membrane  202 , back plate  204  and base plate  206  act as electrodes which are electrically isolated from one another by spacers  216 A,  216 B and  236  such that capacitors are formed between each of the plates. Therefore, when the voltage is applied to each of compliant membrane  202 , back plate  204  and base plate  206 , the electrostatic forces cause them to become clamped together. In one embodiment, the voltage can be applied as a direct current (DC). Alternatively, the voltage can be an alternating current (AC). Since one end  228 ,  232  of compliant membrane  202  and back plate  204 , respectively, are maintained at a vertical position along support member  208 B by springs  212  and  214 , respectively, only their free ends  230 ,  234  move toward one another. Still further, since base plate  206  is stationary, free ends  230 ,  234  of compliant membrane  202  and back plate  204 , respectively, move toward base plate  206  resulting in compliant membrane  202  and back plate  204  having a tilted configuration. 
     Representatively, when the voltage is applied to one or more of compliant membrane  202 , back plate  204  and base plate  206 , the free end  234  of the back plate  204  moves toward the base plate  206  (which is stationary) to tilt the back plate  204  and set the tilt angle  226 . In some embodiments, spacer  236  rests on base plate  206  to set a fixed tilt angle  226 . The free end  230  of compliant membrane  202 , in turn, moves toward back plate  204  to tilt the compliant membrane  202 . In some embodiments, spacers  216 A- 216 B rest on back plate  204  such that compliant membrane  202  is at the same angle as back plate  204 . In this aspect, compliant membrane  202  and back plate  204  can be tilted to an optimal and fine tuned tilt angle  226 , which provides a desired device performance (e.g. directs reflected light toward detector  262 ). For example, in one embodiment, the angle  226  may be an acute angle, for example, less than 4 degrees, for example, 3 degrees or less. It is further contemplated that in some embodiments, different, or intermediate, tilt angles may be achieved depending, for example, upon a voltage applied to the circuitry  224 . For example, in some embodiments, the application of a smaller voltage causes back plate  204  to tilt toward, but not touch, base plate  206 , thus resulting in a smaller tilt angle being set by back plate  204 . The application of a larger voltage will, in turn, draw back plate  204  closer to base plate  206 , thus resulting in a larger tilt angle being set by back plate  204 . Application of a similar voltage to compliant membrane  202  will then cause compliant membrane  202  to tilt to the same angle as back plate  204 . It is further to be understood that spacers  216 A,  216 B and  234  are dimensioned to maintain an even, space or gap between compliant membrane  202 , back plate  204  and base plate  206  so that stiction between the plates is avoided and a controlled minimal stress region of operation between compliant membrane  202  and back plate  204  can be maintained. 
     Detector  262  then detects the reflected light  288  and provides an indication of sound. In particular, compliant membrane  202  vibrates in response to sound (S). The vibration of compliant membrane  202  modulates an intensity of light  288  reflected off of the reflective surface  272  of compliant membrane  202 . In addition, movement of compliant membrane  202  with respect to grating  280  (which is rigid) causes an interference pattern formed by grating  280  to change in size. This modulation in intensity (i.e. change in size of the interference pattern) is detected by detector  262  and used as an indication of the movement of membrane  202  and in turn, provides an indication of sound. It is further to be understood that in order to determine sound from the interference pattern, a distance between compliant membrane  202  and back plate  204  is set such that it is an integer multiple of ¼ λ of the light  288 . 
       FIG. 3  illustrates a top view of the compliant membrane of the optical microphone of  FIG. 2A . From this view, it can be seen that compliant membrane  202  may have a center portion  270  suspended within an outer frame  302  by spokes  304 A,  304 B,  304 C and  304 D. Center portion  270  may be a compliant membrane configured to vibrate in response to acoustic or sound waves while spokes  304 A- 304 D and frame  302  are substantially rigid. In this aspect, center portion  270  may be considered the primary sound pick up surface area of compliant membrane  202  which is used to detect sound while the outer portions (spokes  304 A- 304 D and/or frame  302 ) are used to suspend the center portion  270  in the desired location. In some embodiments, center portion  270 , spokes  304 A- 304 D and frame  302  are made from a single material layer using MEMS processing techniques. In one embodiment, center portion  270  is thinner (in the z-height direction) than spokes  304 A- 304 D and frame  302  such that center portion  270  is considered compliant (can vibrate in response to acoustic waves) while outer portions (spokes  304 A- 304 D and frame  302 ) are substantially rigid and unresponsive to acoustic waves. 
     In one embodiment, center portion  270  is a substantially square shaped membrane having dimensions sufficient to achieve a desired acoustic vibration. In other embodiments, center portion  270  may have any type of quadrilateral shape, or other shapes, for example, a circle, ellipse, oval or the like. In the case of a square shaped center portion  270 , each of spokes  304 A- 304 D may extend from a respective side of center portion  270  to frame  302 . Membrane frame  302 , may in turn, be a square shaped structure. Each of the sides of frame  302  may run parallel to a respective side of center portion  270 . In other embodiments, spokes  304 A- 304 D and frame  302  may be oriented in any manner with respect to center portion  270  that is sufficient to suspend center portion  270  above back plate  204 , base plate  206  and emitter  260 /detector  262  as previously discussed. 
     Spring  212  runs along one side of frame  302  so that it can be used to attach frame  302  to support member  208 B as discussed in reference to  FIG. 2A . Spring  212  can run along an entire length of the side of frame  302 , or less than the entire length. Spring  212  can be made from the same material layer used to form compliant membrane  202  such that it is integrally formed with compliant membrane  202  using MEMS processing techniques. For example, frame  302  may be wider on the side where it is desirable to have spring  212 . Corrugations  306  may then be formed in the extra width portion of frame  302  to form an elastic structure that functions as a spring. In other embodiments, spring  212  may have any structure sufficient to suspend complaint membrane  202  from support member  208 B and allow compliant membrane  202  to tilt as previously discussed in reference to  FIG. 2B . 
       FIG. 4  illustrates a bottom view of the compliant membrane of  FIG. 3 . From this view, it can be seen that the bottom surface of center portion  270  includes a reflective surface  272 . In some embodiments, reflective surface  272  is confined to only the area of center portion  270  since this is the sound pick up area of compliant membrane  202 , and therefore the portion used to provide an indication of sound. In other embodiments, reflective surface  272  is formed along the entire bottom side of compliant membrane  202  (e.g., also along spokes  304 A- 304 D and/or frame  302 ). For example, in embodiments where reflective surface  272  is a coating (e.g. a gold coating), it may be applied along the entire bottom side of compliant membrane  202 . 
     Spacers  216 A,  216 B,  216 C and  216 D are also shown positioned along the bottom side of compliant membrane  202 . Although four spacers  216 A- 216 D are shown positioned along each of spokes  304 A- 304 D, respectively, it is contemplated that any number of spacers may be provided and they may be positioned along any portion of the bottom side of compliant membrane  202  sufficient to space compliant membrane  202  a distance from back plate  204 . Spacers  216 A- 216 D may further have any size and shape suitable for spacing compliant membrane  202  a distance from back plate  204 . Representatively, spacers  216 A- 216 D may be cone, pyramid, cube, or hemispherically shaped structures. Spacers  216 A- 216 D should be of any material sufficient to both mechanically and electrically isolate compliant membrane  202  a distance from back plate  204 . For example, spacers  216 A- 216 D may be made of an insulating material as previously discussed. In one embodiment, spacers  216 A- 216 D may be formed from a different material layer than compliant membrane  202  using MEMS processing techniques. 
       FIG. 5  illustrates a top view of a back plate of the optical microphone of  FIG. 2A . Back plate  204  may be a substantially rigid plate having grating  280 , which can be formed therein by MEMS processing techniques. Back plate  204  may have a similar size and shape as compliant membrane  202 , for example a square shape. Alternatively, back plate  204  may have any type of quadrilateral shape, or other shapes, for example, a circle, ellipse, oval or the like. Grating  280  may have a periodic structure sufficient to split and diffract light emitted from an emitter (e.g. emitter  260 ) into different beams for detection by a detector (e.g. detector  262 ). In some embodiments, the grating  280  causes the formation of an interference pattern which can be used to indicate a movement of compliant membrane  202  in response to sound waves, and in turn, as an indicator of sound. Grating  280  may be formed in a portion of back plate  204  which is aligned with center portion  270  of compliant membrane  202  and emitter  260 /detector  262 , as described in  FIG. 2A . In the illustrated embodiment, grating  280  is formed in a center portion of back plate  204  which, when microphone  200  is assembled, causes grating  280  to be positioned between center portion  270  of compliant membrane  202  and emitter  260 /detector  262 . 
     Spring  214  runs along one side of back plate  204  so that it can be used to attach back plate  204  to support member  208 B as discussed in reference to  FIG. 2A . Spring  214  can run along an entire length of the side of back plate  204  or less than the entire length. Spring  214  can be made from the same material layer used to form back plate  204  such that it is integrally formed with back plate  204  using MEMS processing techniques. For example, back plate  204  may be wider on the side where it is desirable to have spring  214 . Corrugations  406  may then be formed in the extra width portion of back plate  204  to form an elastic structure that functions as a spring. In other embodiments, spring  214  may have any structure sufficient to suspend back plate  204  from support member  208 B and allow back plate  204  to tilt as previously discussed in reference to  FIG. 2B . 
       FIG. 6  illustrates a bottom view of the back plate of  FIG. 5 . From this view, it can be seen that back plate  204  includes a reflective layer  282  along its bottom side. Reflective layer  282  may also, in some embodiments, be formed along the top side of back plate  204 . For example, reflective layer  282  may be formed along all surfaces of grating  280  to form a grating which is reflective from all angles. Reflective layer  282  may be a material layer, which is formed on back plate  204 , or a coating (e.g. a gold coating) which is applied to one or more surfaces of back plate  204 . Alternatively, back plate  204  may be made of a reflective material such that any outer surfaces of back plate  204  are reflective. 
       FIG. 7A  illustrates one embodiment of a processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7A  illustrates substrate  702  having a cavity  701  formed therein. Substrate  702  may be a silicon substrate, for example, a silicon on insulator (SOI) wafer. Cavity  701  may be defined by vertically extending support member  704 A and vertically extending support member  704 B and a base portion  703  of substrate  702 . In one embodiment, cavity  701  is formed within substrate  702  using a MEMS etching process, for example, reactive ion etching (RIE). Alternatively, cavity  701  may be formed on top of substrate  702  by stacking additional material layers and then patterning the layers to form cavity  701 . MEMS microphone  200  may be formed within cavity  701 . 
     Representatively, in one embodiment, a sacrificial layer  706  may be formed on top of the base portion  703  of substrate  702 . Sacrificial layer  706  may be formed by any MEMS processing technique suitable for forming a sacrificial layer. For example, sacrificial layer  706  may be formed by blanket depositing a sacrificial material over substrate  702  using a chemical vapor deposition (CVD) process and then planarizing the layer to provide a desired layer thickness. Sacrificial layer  706  may be made of any material that can be selectively removed or patterned using MEMS processing steps. Representatively, sacrificial layer  706  may be made of silicon dioxide or a silicate glass. 
     Base plate layer  708  may be formed over sacrificial layer  706 . Base plate layer  708  may be formed by any MEMS processing technique suitable for forming a base plate layer, for example, blanket depositing a base plate layer material using CVD. Base plate layer  708  may be made of any material suitable for forming, for example base plate  206  previously discussed in reference to  FIG. 2A . Representatively, base plate layer  708  may be made of a silicon material. 
       FIG. 7B  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7B  shows base plate layer  708  after a processing step in which portions of base plate layer  708  are removed to form a structure suitable for use as a base plate within microphone  200 . For example, base plate layer  708  may be patterned using different etching steps (e.g. reactive ion etching) to have the shape and dimensions of base plate  206  described in reference to  FIG. 2A . Since base plate layer  708  is to be used as the base structure which supports the tilt of other plates (or membranes) (e.g. membrane  202  and back plate  204  discussed in reference to  FIG. 2A ), sacrificial layer  706  should have a thickness equal to the desired distance or gap between the base plate of the microphone and the substrate (e.g. substrate  210 ) so that when sacrificial layer  706  is removed a space or gap of the desired size remains between the structures. 
       FIG. 7C  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7C  illustrates the step of forming a sacrificial layer  710  over base plate layer  708 . Sacrificial layer  710  may be formed using any MEMS processing step suitable for forming a sacrificial layer over another layer. For example, sacrificial layer  710  may be formed by blanket depositing a sacrificial layer material over base plate layer  708  and sacrificial layer  706  using CVD. Sacrificial layer  710  may be substantially similar to sacrificial layer  706 . Sacrificial layer  708  may be of any material that can be selectively removed during a further processing step (e.g. silicon dioxide or silicate glass). 
       FIG. 7D  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7D  illustrates the step of forming a back plate layer  712  over sacrificial layer  710 . Back plate layer  712  may be formed by any MEMS processing step suitable for forming a back plate layer over sacrificial layer  710 . For example, back plate layer  712  may be formed by blanket depositing a back plate layer material over sacrificial layer  710  using CVD. A suitable back plate layer material may be, for example, a silicon material capable of forming a substantially rigid layer that can function as an electrode during operation of the microphone. 
       FIG. 7E  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7E  shows back plate layer  712  after a processing step in which portions of back plate layer  712  are removed to form a structure suitable for use as a back plate within microphone  200 . For example, back plate layer  712  is processed using MEMS processing techniques to have the shape and dimensions of back plate  204  described in reference to  FIG. 2A . Representatively, an RIE processing technique may be used to pattern back plate layer  712  such that it is separated from support member  704 A and includes grating  714  and spring  716 . Grating  714  and spring  716  may be substantially similar to grating  280  and spring  214  previously discussed in reference to  FIG. 2A . 
     It should further be understood that since back plate layer  712  (e.g. back plate  204 ) is designed to be tilted onto base plate layer  708  (e.g. base plate  206 ) in the final product, a distance between back plate layer  712  and base plate layer  708 , as well as a length of back plate layer  712 , are selected to achieve the desired tilt angle. In other words, the tilt angle is controlled by the thickness of sacrificial layer  710  between base plate layer  708  and back plate layer  712 . In this aspect, a thickness of sacrificial layer  710 , is selected to achieve the desired tilt angle between the layers, for example, an acute tilt angle such as an angle of 4 degrees or less, for example, 3 degrees. 
       FIG. 7F  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7F  illustrates the step of forming a sacrificial layer  718  over back plate layer  712 . Sacrificial layer  718  may be formed using any MEMS processing step suitable for forming a sacrificial layer over another layer. For example, sacrificial layer  718  may be formed by blanket depositing a sacrificial layer over back plate layer  712  and sacrificial layer  710  using CVD. Sacrificial layer  718  may be substantially similar to sacrificial layers  706  and  710 . Sacrificial layer  718  may be of any material that can be selectively removed during a further processing step (e.g. silicon dioxide or silicate glass). 
       FIG. 7G  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7G  illustrates the step of forming a compliant membrane layer  720  over sacrificial layer  718 . Compliant membrane layer  720  may be formed by any MEMS processing step suitable for forming a compliant membrane layer  720  over sacrificial layer  718 . For example, compliant membrane layer  720  may be formed by blanket depositing a compliant membrane material over sacrificial layer  718  using CVD. A compliant membrane material may include, but is not limited to, a material capable of forming a membrane that can function as a microphone diaphragm and an electrode during a tilting operation of the microphone, for example, polysilicon or a metallic material. 
       FIG. 7H  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7H  shows compliant membrane layer  720  after a processing step in which portions of compliant membrane layer  720  are patterned to form a structure suitable for use as a compliant membrane (e.g. a diaphragm) within microphone  200 . For example, compliant membrane layer  720  is patterned using an RIE technique to have the shape and dimensions of compliant membrane  202  described in reference to  FIG. 2A . Representatively, RIE may be used to separate compliant membrane layer  720  from support member  704 A as well as to form a more compliant center portion  724  (a portion with reduced thickness), a more rigid frame  760  (a portion thicker than center portion  724 ) and spring  722 . Center portion  724  and spring  722  may be substantially similar to center portion  270  and spring  212  previously discussed in reference to  FIG. 2A  and frame  760  may be substantially similar to frame  302  discussed in reference to  FIG. 3 . 
       FIG. 7I  illustrates one embodiment of another processing step for fabricating the optical microphone of  FIG. 2A .  FIG. 7I  shows formation of an opening  730  within substrate  702 . Opening  730  can be formed by any standard MEMS processing technique, for example, RIE or a deep reactive ion etching (DRIE) step. Opening  730  facilitates removal of sacrificial layers  706 ,  710  and  718 . 
     Representatively,  FIG. 7J  illustrates a processing step in which sacrificial layers  706 ,  710  and  718  have been removed, for example, by a wet or dry etch processing technique. For example, layers  706 ,  710  and  718  may be removed using a wet etching step with a selective wet etchant including hydrofluoric acid (HF). The wet etchant (HF) etches away sacrificial layers  706 ,  710  and  718  without etching, or otherwise damaging, the various layers needed to form the microphone, for example, base plate layer  708 , back plate layer  712  and compliant membrane layer  720 . In some embodiments, portions of sacrificial layers  718  and  710  may be patterned and not completely removed such that spacers  750 ,  752 A and  752 B, which, for example, correspond to spacers  236 ,  216 A and  216 B remain between the layers. 
       FIG. 7J  further illustrates the step of applying a reflective surface  736  to center portion  718  and a reflective surface  734  to grating  714 . Representatively, in one embodiment, reflective surface  736  and reflective surface  734  are formed by introducing a reflective material  732  (e.g. gold coating) through opening  730  within substrate in a manner that allows material  732  to coat center portion  718  and grating  714 . 
     Once each of the layers necessary for operation of microphone  700  are formed, an emitter (e.g. emitter  260 ) and detector (e.g. detector  262 ) can be positioned within opening  730  such that they are aligned with grating  714  and reflective surface  736 . In one embodiment, emitter and detector may be formed monolithically on another substrate using standard MEMS processing techniques, and then positioned within, or aligned with, opening  730 . Microphone  700  may then be mounted within an enclosure (e.g. enclosure  240 ) which can in turn be mounted within the desired electronic device. Alternatively, the emitter and detector may be mounted within an enclosure for the microphone and positioned within opening  730 . In addition, any circuitry (e.g. wires) connected to the various microphone components, for example, base layer  708 , back plate layer  712 , compliant membrane layer  720 , the emitter or the detector may be pre-formed within substrate  702  and support members  704 A- 704 B such that when the components are formed, the circuitry is connected to the components. 
       FIG. 8  illustrates one embodiment of a simplified schematic view of one embodiment of an electronic device in which a MEMS optical microphone, or other MEMS device described herein, may be implemented. As seen in  FIG. 8 , the MEMS device may be integrated within a consumer electronic device  802  such as a smart phone with which a user can conduct a call with a far-end user of a communications device  804  over a wireless communications network; in another example, the MEMS device may be integrated within the housing of a tablet computer. These are just two examples of where the MEMS device described herein may be used, it is contemplated, however, that the MEMS device may be used with any type of electronic device in which a MEMS device, for example, an optical MEMS microphone, is desired, for example, a tablet computer, a desk top computing device or other display device. 
       FIG. 9  illustrates a block diagram of some of the constituent components of an embodiment of an electronic device in which an embodiment of the invention may be implemented. Device  900  may be any one of several different types of consumer electronic devices. For example, the device  900  may be any microphone-equipped mobile device, such as a cellular phone, a smart phone, a media player, or a tablet-like portable computer. 
     In this aspect, electronic device  900  includes a processor  912  that interacts with camera circuitry  906 , motion sensor  904 , storage  908 , memory  914 , display  922 , and user input interface  924 . Main processor  912  may also interact with communications circuitry  902 , primary power source  910 , speaker  918 , and microphone  920 . The various components of the electronic device  900  may be digitally interconnected and used or managed by a software stack being executed by the processor  912 . Many of the components shown or described here may be implemented as one or more dedicated hardware units and/or a programmed processor (software being executed by a processor, e.g., the processor  912 ). 
     The processor  912  controls the overall operation of the device  900  by performing some or all of the operations of one or more applications or operating system programs implemented on the device  900 , by executing instructions for it (software code and data) that may be found in the storage  908 . The processor  912  may, for example, drive the display  922  and receive user inputs through the user input interface  924  (which may be integrated with the display  922  as part of a single, touch sensitive display panel). In addition, processor  912  may send an audio signal to speaker  918  to facilitate operation of speaker  918 . 
     Storage  908  provides a relatively large amount of “permanent” data storage, using nonvolatile solid state memory (e.g., flash storage) and/or a kinetic nonvolatile storage device (e.g., rotating magnetic disk drive). Storage  908  may include both local storage and storage space on a remote server. Storage  908  may store data as well as software components that control and manage, at a higher level, the different functions of the device  900 . 
     In addition to storage  908 , there may be memory  914 , also referred to as main memory or program memory, which provides relatively fast access to stored code and data that is being executed by the processor  912 . Memory  914  may include solid state random access memory (RAM), e.g., static RAM or dynamic RAM. There may be one or more processors, e.g., processor  912 , that run or execute various software programs, modules, or sets of instructions (e.g., applications) that, while stored permanently in the storage  908 , have been transferred to the memory  914  for execution, to perform the various functions described above. 
     The device  900  may include communications circuitry  902 . Communications circuitry  902  may include components used for wired or wireless communications, such as two-way conversations and data transfers. For example, communications circuitry  902  may include RF communications circuitry that is coupled to an antenna, so that the user of the device  900  can place or receive a call through a wireless communications network. The RF communications circuitry may include a RF transceiver and a cellular baseband processor to enable the call through a cellular network. For example, communications circuitry  902  may include Wi-Fi communications circuitry so that the user of the device  900  may place or initiate a call using voice over Internet Protocol (VOIP) connection, transfer data through a wireless local area network. 
     The device may include a microphone  920 . Microphone  920  may be a MEMS optical microphone such as that described in reference to  FIG. 2A-2B . In this aspect, microphone  920  may be an acoustic-to-electric transducer or sensor that converts sound in air into an electrical signal. The microphone circuitry (e.g. circuit  224 ) may be electrically connected to processor  912  and power source  910  to facilitate the microphone operation (e.g. tilting). 
     The device  900  may include a motion sensor  904 , also referred to as an inertial sensor, that may be used to detect movement of the device  900 . Motion sensor  904  could, in some embodiments, include MEMS device  FIG. 1A - FIG. 1B . The motion sensor  904  may include a position, orientation, or movement (POM) sensor, such as an accelerometer, a gyroscope, a light sensor, an infrared (IR) sensor, a proximity sensor, a capacitive proximity sensor, an acoustic sensor, a sonic or sonar sensor, a radar sensor, an image sensor, a video sensor, a global positioning (GPS) detector, an RF or acoustic doppler detector, a compass, a magnetometer, or other like sensor. For example, the motion sensor  904  may be a light sensor that detects movement or absence of movement of the device  900 , by detecting the intensity of ambient light or a sudden change in the intensity of ambient light. The motion sensor  904  generates a signal based on at least one of a position, orientation, and movement of the device  900 . The signal may include the character of the motion, such as acceleration, velocity, direction, directional change, duration, amplitude, frequency, or any other characterization of movement. The processor  912  receives the sensor signal and controls one or more operations of the device  900  based in part on the sensor signal. 
     The device  900  also includes camera circuitry  906  that implements the digital camera functionality of the device  900 . One or more solid state image sensors are built into the device  900 , and each may be located at a focal plane of an optical system that includes a respective lens. An optical image of a scene within the camera&#39;s field of view is formed on the image sensor, and the sensor responds by capturing the scene in the form of a digital image or picture consisting of pixels that may then be stored in storage  908 . The camera circuitry  906  may also be used to capture video images of a scene. 
     Device  900  also includes primary power source  910 , such as a built in battery, as a primary power supply. 
     While certain embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that the invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. For example, the devices and processing steps disclosed herein may correspond to any type of MEMS sensor that can benefit from being able to tilt one or more plates or layers within the sensor, for example, an inertial sensor, an accelerometer, a gyrometer or the like. Still further, in some embodiments, the MEMS sensor includes only two plates, and only one of the plates is movable. For example, the MEMS sensor may include a top plate having a sensor surface, a base plate and circuitry to apply a voltage between the two plates. The voltage causes only one of the plates to move with respect to the other plate (e.g. the movable plate can be the top plate with the sensor, which could be a sound pick up membrane). The description is thus to be regarded as illustrative instead of limiting.

Metadata:
Filing Date: 20140714
Publication Date: 20160802
Grant Date: 20160802
Priority Date: 20140509
Inventors: AGASHE JANHAVI S.
LEE JAE H.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R23/008", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01N21/01", "inventive": true, "first": false, "tree": "[]"}, {"code": "B81C2203/0785", "inventive": false, "first": false, "tree": "[]"}, {"code": "B81C1/00158", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N21/55", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N2201/0612", "inventive": false, "first": false, "tree": "[]"}, {"code": "B81C2201/0174", "inventive": false, "first": false, "tree": "[]"}, {"code": "B81C1/00341", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N21/4788", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2201/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/413", "inventive": false, "first": false, "tree": "[]"}, {"code": "B81C2201/0174", "inventive": false, "first": false, "tree": "[]"}, {"code": "B81C1/00341", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N21/55", "inventive": true, "first": true, "tree": "[]"}, {"code": "B81C1/00158", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01N21/01", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01N2201/0612", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 54367619