CN210781342U - Low-temperature protection MEMS microphone - Google Patents

Abstract

The utility model relates to a microphone field especially relates to a MEMS microphone of low temperature protection, contains packaging substrate, be fixed with the Sensor chip on the packaging substrate, the Sensor chip is connected with the ASIC chip through the bonding wire, the ASIC chip passes through the bonding wire and links to each other with packaging substrate electrical property, the ASIC chip is established ties there is a thermistor, thermistor links to each other with the power, still be fixed with the metal-back on the packaging substrate, there are BIAS end and VOUT end on the Sensor chip, BIAS end links to each other with the BIAS end electrical property of ASIC chip on the Sensor chip, VOUT end links to each other with the VOUT end electrical property of ASIC chip on the Sensor chip, OUT end on the ASIC chip links to each other with aforementioned packaging substrate electrical property through electric capacity, the inside charge pump in addition of ASIC chip, thermistor one end is connected to the feed end of ASIC chip, thermistor links to each other with the power. The device can effectively ensure that the circuit of the MEMS microphone is disconnected when the temperature is too low, and protect the MEMS microphone.

Description

Low-temperature protection MEMS microphone

[ technical field ] A method for producing a semiconductor device

The invention relates to the field of microphones, in particular to an MEMS (micro-electromechanical system) microphone with low-temperature protection.

[ background of the invention ]

MEMS is a Micro-Electro mechanical system (Micro-Electro mechanical system), which refers to a sensor device with a size of several millimeters or less, and the internal structure of the sensor device is generally in the micrometer or nanometer level, and the sensor device is an independent intelligent system. Briefly, the MEMS is a silicon-based sensor formed by miniaturizing mechanical components of a conventional sensor, fixing a device on a silicon wafer (wafer) by a three-dimensional stacking technique, for example, a three-dimensional through-silicon via (TSV) technique, and finally cutting and assembling the device in a specially-customized packaging form according to different application occasions. The MEMS has the advantages of miniaturization and high integration degree which cannot be achieved by the common sensor;

the Sensor chip of the MEMS microphone belongs to a sensitive component and is easily influenced by the outside, and because the distance between two polar plates is extremely small, generally about 2 mu m, the working state of the Sensor can be influenced by the outside environment, and meanwhile, the risk of polar plate short circuit also exists, so that the microphone can be greatly damaged. The microphone can work in certain high and low temperature environments, but beyond the temperature range, the microphone still can be in a working state, and the working state can cause damage to the MEMS microphone.

The invention is developed and proposed aiming at the defects of the prior art.

[ summary of the invention ]

The invention aims to overcome the defects of the prior art and provide a low-temperature protection MEMS microphone, which stops running when the temperature is too low, plays a role in protecting a Sensor and is beneficial to prolonging the service life of the microphone.

The invention can be realized by the following technical scheme:

the invention discloses a low-temperature protected MEMS microphone, which comprises a packaging substrate, wherein a Sensor chip is fixed on the packaging substrate, the Sensor chip is connected with an ASIC chip through a bonding wire, the ASIC chip is electrically connected with the packaging substrate through the bonding wire, a thermistor is connected in series with the ASIC chip, the thermistor is connected with a power supply, a metal shell is also fixed on the packaging substrate, a BIAS end and a VOUT end are arranged on the Sensor chip, the BIAS end on the Sensor chip is electrically connected with the BIAS end of the ASIC chip, the VOUT end on the Sensor chip is electrically connected with the VOUT end of the ASIC chip, an OUT end on the ASIC chip is electrically connected with the packaging substrate through a capacitor, a charge pump is arranged in the ASIC chip, a power supply end of the ASIC chip is connected with one end of the thermistor, and the thermistor is connected with the power supply. This thermistor is negative temperature coefficient thermistor, negative temperature coefficient thermistor both ends temperature is lower more, resistance is big more, it is less with the ASIC chip partial pressure of thermistor series connection, when the temperature is low excessively, thermistor resistance is big, the ASIC chip can't obtain sufficient voltage and start, thereby make the Sensor chip be in unable operating condition, when the temperature risees, thermistor resistance reduces, its partial pressure value diminishes, the ASIC chip can obtain sufficient voltage, thereby make the Sensor chip be in normal operating condition, the purpose through temperature control microphone operating condition can be realized to this design, especially need mention, when extreme low temperature (surpass microphone normal operating temperature), there is fabulous guard action, can prevent that the microphone from appearing the inefficacy of low temperature state.

Preferably, the package substrate is provided with a sound inlet hole.

Preferably, the bonding wire is made of metal materials such as gold, aluminum, copper and the like.

Compared with the prior art, the invention has the following advantages:

when the temperature is too low, the resistance value of the thermistor is large, the ASIC chip cannot obtain enough voltage to start, so that the Sensor chip is in a non-working state, the purpose of controlling the working state of the microphone through the temperature is realized, and particularly, the microphone has an excellent protection effect when the temperature is extremely low (exceeds the normal working temperature of the microphone), and the microphone can be prevented from failing in a low-temperature state.

[ description of the drawings ]

The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings, in which:

FIG. 1 is an exploded view of the present invention;

FIG. 2 is a circuit diagram of the present invention;

FIG. 3 is a diagram of a Sensor chip according to the present invention;

FIG. 4 is a diagram of the working state of the Sensor chip;

in the figure: 1. a metal shell; 2. a bonding wire; 3. an ASIC chip; 4. a Sensor chip; 401. a back electrode; 402. silicon-based; 403. vibrating diaphragm; 5. a thermistor; 6. a package substrate; 61. a sound inlet hole;

[ detailed description ] embodiments

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings:

as shown in fig. 1 to 4, the present invention discloses a low temperature protected MEMS microphone, which comprises a package substrate 6, a Sensor chip 4 fixed on the package substrate 6, the Sensor chip 4 connected to an ASIC chip 3 through a bonding wire 2, the ASIC chip 3 electrically connected to the package substrate 6 through the bonding wire 2, the ASIC chip 3 connected in series to a thermistor 5, the thermistor 5 connected to a power supply, a metal casing 1 fixed on the package substrate 6, the Sensor chip 4 having a BIAS terminal and a VOUT terminal, the BIAS terminal on the Sensor chip 4 electrically connected to the BIAS terminal of the ASIC chip 3, the VOUT terminal on the Sensor chip 4 electrically connected to the VOUT terminal of the ASIC chip 3, the OUT terminal on the ASIC chip 3 electrically connected to the package substrate 6 through a capacitor, a charge pump inside the ASIC chip 3, the charge pump being a switched capacitor type voltage converter, the capacitor being an energy storage element, capable of generating an output voltage larger than the input voltage, the power supply end of the ASIC chip 3 is connected with one end of the thermistor 5, and the thermistor 5 is connected with a power supply. The MEMS microphone has the working principle that an external power supply supplies power to an ASIC chip 3, when the voltage is large enough, the ASIC chip 3 enters a working state, the ASIC chip 3 provides bias voltage for a vibrating diaphragm 403 and a back pole 401 on a Sensor chip 4 through a charge pump in the ASIC chip 3, so that potential difference exists between the vibrating diaphragm 403 and the back pole 401 of the Sensor chip 4, a sound signal is converted into mechanical energy of the vibrating diaphragm 403 under the action of external sound pressure, and meanwhile, compared with the working principle of a parallel plate capacitor, under the condition that the distance between the vibrating diaphragm 403 and the back pole 401 is changed, an electric signal is output from a VOUT end of the Sensor chip 4 and is an initial signal of detected sound, and the signal is output from an OUT end after being processed by the signal ASIC chip 3; thermistor 5 is negative temperature coefficient thermistor 5 ware, negative temperature coefficient thermistor 5 ware both ends temperature is lower, the resistance is big, it is less with the ASIC chip 3 partial pressure of thermistor 5 series connection, when the temperature is low excessively, thermistor 5 resistance is big, ASIC chip 3 can't obtain sufficient voltage and start, thereby make Sensor chip 4 be in unable operating condition, when the temperature risees, thermistor 5 resistance reduces, its partial pressure value diminishes, ASIC chip 3 can obtain sufficient voltage, thereby make Sensor chip 4 be in normal operating condition, the purpose through temperature control microphone operating condition can be realized to this design, it needs to mention especially that, when the extreme low temperature (surpass microphone normal operating temperature), there is fabulous guard action, can prevent that the microphone from appearing the inefficacy of low temperature state.

The package substrate 6 is provided with a sound inlet 61.

Wherein, the bonding wire 2 is made of copper metal.

As shown in fig. 3, the structure of the Sensor chip 4 is shown, the Sensor chip 4 is composed of a diaphragm 403, a back electrode 401 and a silicon substrate 402, the diaphragm 403 and the back electrode 401 are fixed inside a cavity of the silicon substrate 402 by a semiconductor processing technology (etching, polishing, evaporation, etc.), the operation principle of the chip is equivalent to a parallel plate capacitor, the diaphragm 403 and the back electrode 401 constitute upper and lower substrates of the capacitor, charges directionally move under the action of voltage, a stable voltage difference is formed between the upper and lower substrates, when external sound pressure acts on the diaphragm 403, the distance between the diaphragm 403 and the back electrode 401 changes, the formula C ∈ S/4 π kd shows that the capacitance of the capacitor changes accordingly when the distance changes (C: capacitance ∈: dielectric constant, S: the facing area d between the diaphragm 403 and the back electrode 401: the distance between the two plates, k: Q/C), when the distance changes, the output voltage value changes (Q: the constant charge value of the capacitor 403, Q: the constant charge value, U: U-403, U-36, U-v — 3632, when the voltage of the chip is changed, U — 3632, the voltage of the chip is changed after the external sound pressure changes, and the voltage of the chip is changed by the voltage is 1-3632.

The above description is only a preferred embodiment of the present invention, and it should be noted that a person skilled in the art can make various changes, modifications, substitutions and alterations to the embodiments without departing from the technical principles of the present invention, and such changes, modifications, substitutions and alterations should also be regarded as the protection scope of the present invention.

Claims (2)

1. A cryogenically protected MEMS microphone, comprising: contain the packaging substrate, be fixed with the Sensor chip on the packaging substrate, the Sensor chip is connected with the ASIC chip through the bonding wire, the ASIC chip passes through the bonding wire and links to each other with the packaging substrate electrical property, ASIC chip establishes ties has a thermistor, thermistor links to each other with the power, still be fixed with the metal-back on the packaging substrate, there are BIAS end and VOUT end on the Sensor chip, BIAS end links to each other with the BIAS end electrical property of ASIC chip on the Sensor chip, VOUT end links to each other with the VOUT end electrical property of ASIC chip on the Sensor chip, OUT end on the ASIC chip passes through electric capacity and links to each other with aforementioned packaging substrate electrical property, the inside charge pump in addition of ASIC chip, thermistor one end is connected to the feed end of ASIC chip.

2. The cryo-protected MEMS microphone of claim 1, wherein: and the packaging substrate is provided with a sound inlet hole.

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