Microphone MEMS diaphragm and its self-test

Abstract

A device comprising a microelectromechanical system (MEMS) element configured to sense an acoustic signal. The device also comprises a circuit system configured to enable a microphone element to sense an acoustic signal. The circuit system is further configured to disable the microphone element to prevent the microphone element from sensing an acoustic signal. It should be appreciated that the circuit system is further configured to apply a test signal to the MEMS element when the microphone element is disabled. The microphone element outputs a signal to the circuit system in response to the test signal. The circuit system determines that a diaphragm of the MEMS element is operating abnormally in response to an output signal having a first value, and the circuit system determines that the diaphragm of the MEMS element is operating normally in response to an output signal having a second value.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application serial number 17 / 158,983, filed on January 26, 2021, entitled “MICROPHONE MEMSDIAPHRAGM AND SELF-TEST THEREOF.” Background Art

[0003] MEMS ("micro-electromechanical systems") are a class of devices that are manufactured using semiconductor-like processes and exhibit mechanical properties. MEMS devices may include a membrane that has the ability to move or deform in response to a stimulus. One class of microphones utilizes a MEMS element that deforms in response to acoustic waves (i.e., sound). A MEMS element may include a stationary plate and a movable plate (i.e., a membrane that deforms in response to the acoustic waves). The stationary plate and the movable plate form a capacitor that changes capacitance as the membrane deforms in response to the acoustic waves. Common failures and performance degradations are caused by damage to the membrane (e.g., diaphragm) of the MEMS element. The diaphragm may be damaged or torn due to acoustic overload, mechanical stress, and / or electrostatic charge, resulting in partial or total loss of the microphone's acoustic sensitivity.

[0004] Conventionally, MEMS components and their functionality are tested externally, for example, by applying sound waves, and if no response is recorded, it can be inferred that the membrane has been damaged or torn. Unfortunately, the device itself cannot be tested for the functionality and health of its membrane / diaphragm. Summary of the invention

[0005] Therefore, for a device having a microphone, a need arises to perform a self-test to check whether its membrane (i.e., diaphragm) has been damaged or torn. According to some embodiments, a circuit system may be used to bias the diaphragm of a MEMS microphone by applying an electric charge, thereby enabling the diaphragm to deform in response to sound waves. The circuit system may de-bias the diaphragm of the MEMS microphone during the self-test, thereby disabling the diaphragm or reducing the sensitivity of the diaphragm to sound waves. Once the MEMS microphone is de-biased, the circuit system may apply a test signal to the MEMS microphone so that it substantially responds to the test signal with minimal interference from the sound waves. An output signal received from the MEMS microphone is processed by the circuit system, and if the signal has a first value (or range), it is determined that the membrane (i.e., diaphragm) is not damaged or torn, and if the signal has a second value (or range), it is determined that the diaphragm is damaged or torn.

[0006] In some embodiments, the device includes a MEMS element configured to sense an acoustic signal. The device also includes a circuit system configured to enable a microphone element to sense an acoustic signal. The circuit system is further configured to disable the microphone element to prevent the microphone element from sensing an acoustic signal. It should be appreciated that the circuit system is further configured to apply a test signal to the MEMS element when the microphone element is disabled. The microphone element outputs a signal to the circuit system in response to the test signal. The circuit system determines that the diaphragm of the MEMS element is operating abnormally in response to an output signal having a first value, and the circuit system determines that the diaphragm of the MEMS element is operating normally in response to an output signal having a second value.

[0007] It should be appreciated that the test signal may be applied to the diaphragm, backplate and / or stem element of the MEMS element. When the diaphragm is operating normally, the diaphragm and backplate of the MEMS element form a capacitive element. The stem element is a carrier for thinner silicon device substrates.

[0008] In some embodiments, the circuit system may include a charge pump. The charge pump is configured to bias the MEMS element when the microphone element is enabled. In addition, the charge pump is configured to de-bias the MEMS element when the microphone element is disabled.

[0009] It should be appreciated that the test signal can be programmed via the circuit system. According to some embodiments, the diaphragm of the MEMS element has a larger amplitude response to the test signal when the diaphragm of the MEMS element is not operating normally than when the diaphragm of the MEMS element is operating normally.

[0010] According to some embodiments, the device may further include a processing unit configured to initiate a self-test mode. When the processing unit initiates the self-test mode, the circuit system disables the microphone element to prevent the microphone element from sensing sound waves.

[0011] In some embodiments, a method includes disabling a microphone element of a MEMS element that is configured to sense sound waves. The method further includes applying a test signal to the MEMS element of the microphone element. In some embodiments, the method further includes receiving an output signal from the MEMS element of the microphone element in response to the test signal. Determine an amplitude response of the output signal. The method further includes determining that a diaphragm of the MEMS element is not operating normally in response to the amplitude response of the output signal being greater than a threshold. According to some non-limiting examples, the method further includes determining that a diaphragm of the MEMS element is operating normally in response to the amplitude response of the output signal being less than a threshold.

[0012] It should be appreciated that disabling may include terminating the application of charge from the charge pump to the MEMS element. In some non-limiting examples, applying includes applying a test signal to a diaphragm of the MEMS element. When the diaphragm is operating normally, the diaphragm and backplate of the MEMS element form a capacitive element. In some embodiments, the test signal may be applied to the backplate of the MEMS element. In some non-limiting examples, the MEMS element includes a handle element, and the test signal is applied to the handle element. It should be appreciated that the handle element is a carrier for thinner silicon device substrates. It should be appreciated that the test signal may be programmable. It should be appreciated that when the diaphragm of the MEMS element is operating abnormally, the amplitude response of the amplitude signal in response to the test signal is greater than when the diaphragm of the MEMS element is operating normally. The method may further include receiving a signal initiated from a test mode. The microphone is disabled in response to the received signal for initiating a self-test mode.

[0013] These and other features and aspects of the concepts described herein may be better understood with reference to the following drawings, description, and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1A A top perspective view of a packaged microphone with a MEMS microphone die is shown in accordance with an aspect of the present embodiment.

[0015] Figure 1B Shows Figure 1A Bottom perspective view of the packaged microphone in FIG.

[0016] Figure 1C It shows that Figure 1A Cross-sectional view of a packaged microphone oriented in center.

[0017] Figure 1D A cross-sectional view of a similar packaged microphone with a bottom port is shown in accordance with one aspect of the present embodiment.

[0018] Figure 2 A MEMS microphone die according to one aspect of the present embodiment is shown.

[0019] Figure 3 A device including a MEMS microphone having self-test capabilities according to some embodiments is shown.

[0020] Figure 4 A MEMS element according to some embodiments is shown.

[0021] Figure 5 Circuitry for initiating a self-test of a MEMS microphone is shown in accordance with some embodiments.

[0022] Figure 6 Analog front end circuitry for applying a test signal to a MEMS element during self-test is shown in accordance with some embodiments.

[0023] Figure 7 A method of performing a self-test on a MEMS microphone according to one aspect of the present embodiment is shown. DETAILED DESCRIPTION

[0024] Before describing various embodiments in more detail, it should be understood that the embodiments are not limiting, as the elements in such embodiments may vary. It should also be understood that the specific embodiments described and / or illustrated herein have elements that can be easily separated from the specific embodiments and optionally combined with any of several other embodiments or can replace elements in any of several other embodiments described herein.

[0025] It should also be understood that the terms used herein are for the purpose of describing certain concepts, and the terms are not intended to be limiting. Unless otherwise specified, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the embodiments belong.

[0026] Unless otherwise indicated, ordinal number (for example, first, second, third, etc.) is used to distinguish or identify different elements or steps in a group of elements or steps, and does not provide sequence or numerical limit to the elements or steps of its embodiment.For example, "first", "second" and "third" elements or steps do not need to appear in this order, and its embodiment is not limited to three elements or steps.It should also be understood that, unless otherwise indicated, any label, such as "left", "right", "front", "back", "top", "middle", "bottom", "beside", "forward", "reverse", "overlying", "underlying", "up", "down", or other similar terms, such as "above", "below", "higher than", "lower than", "below", "between", "above", "vertical", "horizontal", "proximal end", "distal end", "formed", "structured", "reduced", "applied", "pulled", "bent", "terminated", "detected", "disabled", "received", "determined", etc., is used for convenience, and is not intended to imply any specific fixed position, orientation or direction, for example.On the contrary, such labels are used to reflect such as relative position, orientation or direction. It is also to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0027] Terms such as "on," "overlying," "above," "below," etc. are understood to refer to elements that may be in direct contact or may have other elements in between. For example, two layers may be in overlying contact, with one layer being on top of the other and the two layers being in physical contact. In another example, the two layers may be separated by one or more layers, with a first layer being on top of a second layer and one or more intermediate layers being between the first and second layers, such that the first and second layers are not in physical contact.

[0028] A device having a microphone with a MEMS element that is capable of performing a self-test to check the health and operation of a membrane (i.e., diaphragm). In other words, the device can initiate a self-test automatically or in response to a user selection. Once in self-test mode, it can be determined whether the diaphragm has been damaged or torn. According to some embodiments, the microphone may include a MEMS element having a backplate, a diaphragm, and a handle. The handle typically refers to a thicker substrate that serves as a carrier for a thinner silicon device substrate. The diaphragm is configured to deform in response to sound waves and forms a capacitor together with the backplate (stationary plate). Thus, the stored capacitive charge changes as the diaphragm moves, thereby sensing sound waves.

[0029] A circuit system such as an application specific integrated circuit (ASIC) may be coupled to the MEMS element. The circuit system biases the MEMS element (diaphragm) during normal operation (i.e., not in self-test mode), for example using a charge pump, so that the diaphragm is moved in response to sound waves. Once in the self-test mode, the circuit system de-biases the diaphragm to reduce the sensitivity of the diaphragm to sound waves. In some embodiments, de-biasing the diaphragm renders the diaphragm incapable of responding to sound waves.

[0030] In the self-test mode, the circuit system applies a test signal to the MEMS element (e.g., a test signal applied to the diaphragm, a test signal applied to the handle, a test signal applied to the backplate, or any combination thereof). It should be appreciated that the test signal may be programmable (e.g., the value of the test signal (e.g., amplitude, voltage) may be changed, or the shape of the injected signal (e.g., square wave, duty cycle, frequency, etc.) may be changed, etc.). The MEMS element outputs a signal in response to the received test signal. The output signal may be associated with the charge (i.e., voltage) stored on the capacitive element (i.e., the backplate and the diaphragm). The circuit system receives and processes the output signal from the MEMS element. If the processed signal is determined to have a first value (such as a nominal value less than 10 mV) or range, it is determined that the diaphragm is operating normally and is not damaged, and if the processed signal is determined to have a second value (greater than 100 mV) or range, it is determined that the diaphragm is operating abnormally. In other words, when the diaphragm is damaged or torn, it will experience a high amplitude level when the test signal is applied, and when the diaphragm is not damaged, it will experience a lower amplitude level when the test signal is applied.

[0031] It should be appreciated that the term sound wave has been used interchangeably with sound / audio signal.It should also be appreciated that throughout this application the term membrane has been used interchangeably with diaphragm. Figure 1A-Figure 1D and Figure 2 For a general discussion of MEMS components in microphones, Figure 3-Figure 7 The architecture and process steps for self-testing are described to determine if the diaphragm of a MEMS component is damaged or torn.

[0032] Figure 1A A MEMS microphone die 16 (in FIG. Figure 1C , Figure 1D and Figure 2 ) is shown in a top perspective view of the packaged microphone 10.

[0033] The packaged microphone 10 shown has a package base 12 that, together with a corresponding cover 14, forms an internal cavity that contains a microphone chip 16 and, if desired, a separate microphone circuit chip 18 (both dies 16 and 18 are in the Figure 1C and Figure 1D 1 and discussed below). The cover 14 in this embodiment is a cavity-type cover having four walls extending generally orthogonally from the top inner surface to form a cavity. In the illustrative embodiment, the cover 14 is formed of metal or other conductive material to shield the microphone die 16 from electromagnetic interference. The cover 14 is secured to the top surface of the substantially planar package base 12 to form an internal chamber.

[0034] The cover 14 also has an audio input port 20 that enables sound waves (i.e., audio signals) to enter the chamber. However, in alternative embodiments, the audio port 20 is in another location, such as through the package base 12, or through one of the side walls of the cover 14. The audio signal entering the internal chamber interacts with the microphone chip 16 to generate an electrical signal, which, together with additional (external) components (e.g., a speaker and accompanying circuitry), generates an output audible signal corresponding to the input audible signal.

[0035] Figure 1B Shows Figure 1A 1 is a perspective view of the bottom surface 22 of the packaged microphone in FIG. The bottom surface 22 of the package base 12 has a plurality of contacts 24 that are used to electrically connect (and, in many intended uses, physically connect) the microphone die 16 to a substrate such as a printed circuit board or other electrical interconnection device. The packaged microphone 10 can be used in any of a variety of applications. For example, the packaged microphone 10 can be used with mobile phones, landline phones, computer equipment, video games, hearing aids, hearing instruments, biometric security systems, two-way radios, public address systems, and other devices that convert signals. In fact, it is contemplated that the packaged microphone 10 can be used as a speaker to produce an audible signal from an electronic signal.

[0036] In the illustrative embodiment, package base 12 may be a printed circuit board material such as FR-4, or a pre-molded lead frame type package (also referred to as a "pre-molded package"). Other embodiments may use different package types such as ceramic cavity packages. Therefore, the discussion of a particular type of package is for illustrative purposes only.

[0037] Figure 1C Shows a cross Figure 1A 1. A cross-sectional view of packaged microphone 10 oriented along line CC in FIG. As shown and noted above, lid 14 and base 12 form the mentioned internal chamber for containing MEMS microphone die 16 and electronics 18 for controlling and driving microphone die 16. In the illustrative embodiment, the electronics are implemented as a second independent integrated circuit, such as an application specific integrated circuit ("ASIC 18"). However, other embodiments may form the MEMS microstructure and the electronic circuitry on a single die.

[0038] An adhesive or another fastening mechanism secures both the microphone die 16 and the ASIC die 18 to the base 12. Wire bonds electrically connect the microphone die 16 and the ASIC die 18 to contact pads (not shown) on the interior of the package base 12.

[0039] Although a top port packaged microphone design has been illustrated, some embodiments position the input port at other locations, such as through the base 12. For example, Figure 1D A cross-sectional view of a similar packaged microphone 10 is schematically shown, wherein the microphone die 16 covers the input port, thereby creating a large back cavity. Other embodiments, not shown, position the microphone die 16 so that it does not cover the input port 20 through the base 12. Discussion of a particular packaged microphone is for illustrative purposes only. Therefore, with respect to Figure 1A-Figure 1D The discussed packaged microphone 10 is not intended to be limiting of all embodiments of the present invention.

[0040] Figure 2 A MEMS microphone die 16 (also referred to as a “microphone chip”) is shown in accordance with one aspect of the present embodiment. The microphone die 16 includes, among other things, a stationary portion 26 that supports a flexible diaphragm 30 and forms a variable capacitor 28 with the flexible diaphragm 30 .

[0041] In the illustrative embodiment, the stationary portion 26 includes a backplate 32 (shown in subsequent figures and discussed below) formed of single crystal silicon (e.g., the top layer of a silicon-on-insulator wafer discussed below) and other deposited layers, while the diaphragm 30 is formed only of a deposited material such as deposited polycrystalline silicon. However, other embodiments use other types of materials to form the stationary portion 26 and the diaphragm 30. For example, a single crystal silicon bulk wafer and / or some deposited material can form the stationary portion 26. In a similar manner, a single crystal silicon bulk wafer, a portion of a silicon-on-insulator wafer, or some other deposited material can form the diaphragm 30. It should be appreciated that the stationary portion 26 of the microphone die 16 has a backplate 32, which together with the diaphragm 30 can form a variable capacitor. The diaphragm 30 deforms in response to sound waves, causing the variable capacitor to change the capacitive charge stored thereon.

[0042] The springs 34 movably and integrally connect the periphery of the diaphragm 30 to the stationary portion 26 of the microphone die 16. The springs 34 effectively form a plurality of holes 36 that allow at least a portion of the audio / acoustic signal to pass through the diaphragm 30. These holes 36, which may also be referred to as "diaphragm holes 36", may be any shape required by the application, such as slots, circular holes, or some irregular shape. The electrical contacts 25 on the top surfaces of the die 16 and 18 are Figure 1C and Figure 1D The wire bonds shown provide electrical connections.

[0043] Figure 3A device including a MEMS microphone with self-test capabilities according to some embodiments is shown. Microphone element 310 may include MEMS element 320 (e.g., backplate, diaphragm, and stem). The diaphragm of MEMS element 320 may deform in response to sound 302 (also referred to as sound waves). MEMS element 320 outputs signal 322 in response to diaphragm movement. Circuit system 330 receives and processes acoustic analog signal 322 to generate an acoustic signal such as output signal 332.

[0044] According to some embodiments, the circuit system 330 can initiate a self-test mode to test the health of the diaphragm of the MEMS element 320. It should be appreciated that the self-test can be initiated automatically or in response to a user's selection thereof. In the self-test mode, the circuit system 330 de-biases the diaphragm of the MEMS element 320 (or reduces the MEMS bias voltage) in order to reduce its sensitivity to sound waves (or disable its response to sound waves). In other words, interference from sound waves is reduced.

[0045] Once debiased, the diaphragm of the MEMS element 320 becomes substantially insensitive to the acoustic wave 302. The circuit system 330 can transmit a test signal 332 to the MEMS element 320. The test signal 332 can be programmable. For example, the amplitude of the test signal 332 can be changed, the duty cycle can be adjusted, the frequency can be modified, the shape can be adjusted (e.g., a square wave as opposed to a sine wave), etc. The test signal 332 can be applied to one or more locations of the MEMS element 320. For example, referring now to Figure 4 A MEMS element 320 is shown in accordance with some embodiments. In this non-limiting example, the MEMS element 320 may include a backplate 410, a diaphragm 420, and a stem 430. As discussed above, the stem 430 wafer generally refers to a thicker substrate that serves as a carrier for a thinner silicon device substrate (e.g., diaphragm 420). The diaphragm 420 and the backplate 410 form a capacitor. The diaphragm 420 moves and deforms in response to a stimulus (e.g., sound 302, test signal 332, etc.). Return to Reference Figure 3 , the test signal 332 may be applied to the back plate 410, the diaphragm 420 and / or the stem 430. The MEMS element 320 outputs a signal 322 in response to the test signal 332.

[0046] The circuit system 330 receives the output signal 322 and processes it (e.g., amplifies, low-pass filters / band-pass filters, etc.). Once processed, the circuit system 330 can determine whether the diaphragm 420 of the MEMS element 320 is damaged. Generally speaking, a higher amplitude response from the MEMS element 320 is associated with a damaged diaphragm 420, while a lower amplitude is associated with an undamaged diaphragm 420. Thus, in some embodiments, an output signal 322 processed to have an amplitude of less than 10mV can be associated with an undamaged diaphragm 420, and an output signal 322 with an amplitude greater than 100mV can be associated with a damaged diaphragm 420. Therefore, the circuit system 330 can output a signal 332 (e.g., a binary value) indicating whether the diaphragm 420 is damaged or undamaged. In normal operating mode and not in self-test mode, the output signal 332 can be an output acoustic analog signal detected by the microphone element 310.

[0047] Reference now Figure 5 , shows a circuit system 330 that initiates a self-test of a MEMS microphone according to some embodiments. In this non-limiting example, the circuit system 330 may include a charge pump 510, an analog front end 520 unit, a signal processing 530 unit, and a sampling and averaging 540 unit. As discussed above, during a normal operating mode (i.e., not in a self-test mode), the MEMS element 320 of the microphone is biased to increase its sensitivity to acoustic waves. Thus, the charge pump 510 may apply a charge to the MEMS element 320 to bias the MEMS element 320. The acoustic signal sensed by the MEMS element 320 is an acoustic analog signal 322 received by the analog front end 520 unit. The acoustic analog signal 322 is processed by the signal processing 530 unit, and then sampled and averaged by the sampling and averaging 540 unit to generate an output signal 332 (i.e., an audio output).

[0048] In the self-test mode, a processor (not shown) may send a notification signal to the microphone element 310 that the device is entering the self-test mode. In the self-test mode, the MEMS element 320 is unbiased to reduce its sensitivity to sound waves. Thus, once in the self-test mode, the charge pump 510 does not apply charge to the MEMS element 320. The analog front end 520 may apply a test signal 332 (as described above) to the MEMS element 320. The test signal 332 may be applied to one or more locations of the MEMS element 320 (e.g., the back plate 410, the diaphragm 420, and / or the handle 430), thereby generating a voltage across the capacitive element (if the diaphragm 420 is not damaged). In response to the test signal 332, the MEMS element 320 generates an acoustic simulation signal 322. The acoustic simulation signal 322 is received by the analog front end 520 unit. In some non-limiting examples, the analog front end 520 may include a filter (e.g., a low-pass filter, a band-pass filter, etc.). When in the self-test mode, the filtered signal may be inversely proportional to the capacitance of the capacitive element. Thus, when the capacitive element (i.e., back plate 410 and diaphragm 420) is not damaged, a small amplitude is generated as the acoustic output signal 522. Conversely, when the capacitive element is damaged, a large amplitude is generated as the acoustic output signal 522.

[0049] In some embodiments, the acoustic output signal 522 is processed by a signal processing 530 unit, and sampled and averaged by a sampling and averaging 540 unit. It should be appreciated that the signal processing 530 unit and the sampling and averaging 540 unit may be integrated within the analog front end 520 as some non-limiting examples. It should be appreciated that the sampling and averaging 540 unit may be used to statistically meaningfully determine whether the diaphragm 420 is damaged or undamaged. In addition, it should be appreciated that the signal processing unit 530 and / or the sampling and averaging 540 unit may be used to convert (one or more) analog signals into (one or more) digital signals.

[0050] The signal processing 530 unit can determine whether the diaphragm 420 of the MEMS 320 element is not damaged based on the amplitude. For example, for an amplitude less than 10mV, it can be determined that the diaphragm 420 is not damaged; and for an amplitude greater than 100mV, it can be determined that the diaphragm 420 is damaged. According to some embodiments, the test signal 332 can be a plurality of signals injected at a specific frequency. Thus, a determination can be made for each test signal (i.e., a pass / fail of the diaphragm 420), and each test signal can be sampled and averaged so as to make a pass / fail determination in a more statistically meaningful manner. It should be appreciated that in some embodiments, the output signal of the signal processing 530 unit can be sampled and averaged by the sampling and averaging 530 unit over several cycles of the test signal 332. The sampled and averaged value can be compared to a first threshold value (e.g., less than 10 mV) to determine that the diaphragm 420 is not damaged, and the sampled and averaged value can be compared to a second threshold value (e.g., greater than 100 mV, greater than 10 mV, etc.) to determine that the diaphragm 420 is damaged. The output signal 332 in the self-test mode is a determination of whether the diaphragm 420 is damaged or not damaged. It should be appreciated that the threshold value can be a digitally programmable threshold value.

[0051] Reference now Figure 6According to some embodiments, the analog front end circuit system applies the test signal to the MEMS element during the self-test. The analog front end 520 may include switches 632, 634, and 636 to operably couple the test signal 332 to the desired element of the MEMS 320 element. For example, when the switch 632 is turned on during the self-test mode, the test signal 332 is applied to the diaphragm 420. Similarly, when the switch 634 is turned on during the self-test mode, the test signal 332 is applied to the handle 430. In some non-limiting examples, when the switch 636 is turned on during the self-test mode, the test signal 332 is applied to the backplate 410. It should be appreciated that more than one switch may be turned on at the same time, for example, if the switches 632 and 636 are turned on at the same time, the test signal 332 may be applied to both the diaphragm 420 and the backplate 410. It should be appreciated that the embodiments are described above with respect to differential signal outputs. However, it should be appreciated that the embodiments should not be construed as being limited thereto. For example, a single-ended signal may be used. It should be appreciated that when the diaphragm is in normal operation, the diaphragm and backplate of the MEMS element form a capacitive element. It should be appreciated that in some embodiments, a test signal may be applied to the diaphragm of the MEMS element. In some non-limiting examples, the test signal may be applied to the backplate of the MEMS element. In yet another non-limiting example, the test signal may be applied to the handle (i.e., a carrier for a thinner silicon device substrate) element of the MEMS. It should be appreciated that the test signal may have a shape, frequency, and amplitude. For example, the test signal may be a square wave, a triangular wave, or a sine wave having a frequency ranging between 10 Hz and 10 MHz and an amplitude between 10 mV peak to 10 V peak.

[0052] Figure 7 A method of performing a self-test on a MEMS microphone according to one aspect of the present embodiment is shown. At step 710, optionally, a signal to initiate a self-test mode may be received (e.g., received from a processor), initiated by a user, etc. At step 720, a microphone element configured to sense sound waves may be disabled. In other words, the sensitivity of the MEMS 320 element to sound waves may be reduced (e.g., by de-biasing the MEMS 320 element). At step 730, a test signal is applied to the MEMS element of the microphone element. At step 740, an output signal is received from the MEMS element of the microphone element in response to the test signal. At step 750, an amplitude response of the output signal is determined. At step 760, a diaphragm of the MEMS element is determined to be abnormally operated in response to the amplitude response of the output signal being greater than a first threshold. At step 770, a diaphragm of the MEMS element is determined to be normally operated in response to the amplitude response of the output signal being less than a second threshold.

[0053] Although the embodiments have been described and / or illustrated by specific examples, and although these embodiments and / or examples have been described in considerable detail, applicants do not intend to limit or in any way limit the scope of the embodiments to such details. Additional adaptations and / or modifications of the embodiments may readily occur, and in their broader aspects, the embodiments may encompass these adaptations and / or modifications. Therefore, deviations from the foregoing embodiments and / or examples may be made without departing from the scope of the concepts described herein. The implementations described above and other implementations fall within the scope of the appended claims.

Claims

1. A device, comprising: a microphone element, the microphone element comprising a micro-electromechanical system (MEMS) element configured to sense acoustic waves; as well as circuitry configured to enable the microphone element to sense the sound waves, and the circuitry further configured to disable the microphone element to prevent the microphone element from sensing the sound waves, and wherein the circuitry is further configured to apply a test signal to the MEMS element when the microphone element is disabled, wherein the microphone element outputs a signal to the circuit system in response to the test signal, and wherein the circuit system determines that the diaphragm of the MEMS element is operating abnormally in response to the output signal being greater than a first threshold, and wherein the circuit system determines that the diaphragm of the MEMS element is operating normally in response to the output signal being less than a second threshold.

2. The device according to claim 1, wherein: The test signal is applied to the diaphragm of the MEMS element, wherein the diaphragm and a back plate of the MEMS element form a capacitive element when the diaphragm is operating normally.

3. The device of claim 1, wherein: The test signal is applied to a back plate of the MEMS element, wherein the diaphragm and the back plate of the MEMS element form a capacitive element when the diaphragm is operating normally.

4. The device of claim 1, wherein: The MEMS element includes a handle element, and wherein the test signal is applied to the handle element, and wherein the handle element is a carrier for a thinner silicon device substrate.

5. The device of claim 1, wherein: The circuit system further includes a charge pump, and wherein the charge pump is configured to bias the MEMS element when the microphone element is enabled, and wherein the charge pump is configured to de-bias the MEMS element when the microphone element is disabled.

6. The device of claim 1, wherein: The test signal is programmable via the circuit system.

7. The device of claim 1, wherein: The test signal is a square wave having a frequency ranging between 10 Hz and 10 MHz and an amplitude between 10 mV peak and 10 V peak.

8. The device of claim 1, wherein: The diaphragm of the MEMS element has a larger amplitude response to the test signal when the diaphragm of the MEMS element is not operating normally than when the diaphragm of the MEMS element is operating normally.

9. The apparatus of claim 1, further comprising a processing unit configured to initiate a self-test mode, wherein: When the processing unit initiates the self-test mode, the circuit system disables the microphone element to prevent the microphone element from sensing the sound wave.

10. A method comprising: disabling a microphone element of a micro-electromechanical system (MEMS) element configured to sense acoustic waves; applying a test signal to the MEMS element of the microphone element; receiving an output signal from the MEMS element of the microphone element in response to the test signal; determining an amplitude response of the output signal; as well as In response to the amplitude response of the output signal being greater than a first threshold, it is determined that the diaphragm of the MEMS element is not operating normally.

11. The method of claim 10, wherein: The applying includes applying the test signal to the diaphragm of the MEMS element, wherein the diaphragm and a back plate of the MEMS element form a capacitive element when the diaphragm is operating normally.

12. The method of claim 10, wherein: The test signal is applied to a back plate of the MEMS element, wherein the diaphragm and the back plate of the MEMS element form a capacitive element when the diaphragm is operating normally.

13. The method of claim 10, wherein: The MEMS element includes a handle element, and wherein the test signal is applied to the handle element, and wherein the handle element is a carrier for a thinner silicon device substrate.

14. The method of claim 10, wherein: The test signal is programmable.

15. The method of claim 10, wherein: The amplitude response of the amplitude signal in response to the test signal is greater when the diaphragm of the MEMS element is not operating normally than when the diaphragm of the MEMS element is operating normally.

16. The method of claim 10, further comprising receiving a signal initiating a self-test mode, wherein: The microphone is disabled in response to receiving a signal to initiate the self-test mode.

17. The method of claim 10, further comprising determining that the diaphragm of the MEMS element is operating normally in response to the amplitude response of the output signal being below a second threshold.

18. The method of claim 10, wherein: The test signal is a sine wave having a frequency ranging between 10 Hz and 10 MHz and an amplitude between 10 mV peak and 10 V peak.

19. A device, comprising: a microphone element, the microphone element comprising a micro-electromechanical system (MEMS) element configured to sense acoustic waves; as well as a circuit system configured to enable the microphone element to sense the acoustic wave, and the circuit system is further configured to disable the microphone element when in a self-test mode to prevent the microphone element from sensing the acoustic wave, wherein the circuit system includes a plurality of switches configured to apply a test signal to a plurality of test positions of the MEMS element when the microphone element is disabled, wherein the microphone element outputs a signal to the circuit system in response to the test signal, and wherein the circuit system determines that the diaphragm of the MEMS element is operating abnormally in response to the output signal having a first value, and wherein the circuit system determines that the diaphragm of the MEMS element is operating normally in response to the output signal having a second value.

20. The apparatus of claim 19, wherein: The multiple test locations include the diaphragm of the MEMS element, a backplate of the MEMS element that forms a capacitive element when the diaphragm is operating normally, and a handle element, and wherein the test signal is applied to the handle element, and wherein the handle element is a carrier for a thinner silicon device substrate.

21. The apparatus of claim 19, wherein: The test signal is programmable.

22. The apparatus of claim 19, wherein: The test signal is a triangle wave having a frequency ranging between 10 Hz and 10 MHz and an amplitude between 10 mV peak and 10 V peak.

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