CN111510844B

CN111510844B - MEMS microphone trimming device and trimming method

Info

Publication number: CN111510844B
Application number: CN202010399093.5A
Authority: CN
Inventors: 刘宏志
Original assignee: Wuxi Weil Semiconductor Co ltd
Current assignee: Shandong Ganxin Semiconductor Co ltd
Priority date: 2020-05-12
Filing date: 2020-05-12
Publication date: 2021-09-24
Anticipated expiration: 2040-05-12
Also published as: CN111510844A

Abstract

The present application discloses a trimming device for a MEMS microphone and a trimming method thereof. The trimming method includes: obtaining an initial sensitivity of the MEMS microphone according to a first output signal provided by the MEMS microphone; selecting according to the initial sensitivity matching first data; and programming the first data into the MEMS microphone, wherein the gain value of the MEMS microphone is configured by the first data, so that the sensitivity of the MEMS microphone is configured at within the preset range. The trimming method configures corresponding gain values for different MEMS microphones, so that the sensitivity of all MEMS microphones is within a preset range, so that the sensitivity of all trimmed MEMS microphones achieves a highly consistent effect.

Description

Trimming device and trimming method of MEMS microphone

Technical Field

The invention relates to trimming technology, in particular to a trimming device of an MEMS microphone and a trimming method thereof.

Background

The silicon Microphone is a Microphone manufactured based on Micro-Electro-Mechanical System (MEMS) technology, and compared with a traditional polymer material diaphragm of an Electret Condenser Microphone (ECM), the MEMS Microphone has stable performance at different temperatures, and the sensitivity of the MEMS Microphone is not influenced by temperature, vibration, humidity and time. However, MEMS microphones require an external bias voltage provided by an Application Specific Integrated Circuit (ASIC), whereas ECMs do not. Effective bias voltages will allow MEMS microphones to maintain stable acoustic and electrical parameters throughout the operating temperature range, and also support microphone designs with different sensitivities. With the progress of the times and the development of technologies, the sensitivity of the application end to the MEMS microphone is required to be higher and higher, for example, most of the products in the past only require the standard sensitivity to be plus or minus 3dB to meet the requirement. At present, for example, smart phones, smart speakers and the like need to ensure high requirements that the standard sensitivity is plus or minus 1dB or even plus or minus 0.5 dB. The electrical performance of pure circuit chips such as ASIC wafers is easy to achieve high consistency, but the MEMS wafers cannot achieve the consistency of the ASIC wafers, MEMS monomers have certain difference, so that the MEMS and the ASIC are assembled to have certain fluctuation error, if the sensitivity of each MEMS microphone is required to be highly consistent, one customized ASIC chip needs to be burnt and repaired for each MEMS sensor to achieve standard sensitivity, and two important parameters of burning are VBIAS (MEMS bias voltage) and GAIN (ASIC output GAIN).

Therefore, it is desirable to further improve the trimming method and the trimming device so that the sensitivity of each MEMS microphone is highly uniform.

Disclosure of Invention

The invention aims to provide an improved trimming method and a trimming device, which are used for solving the technical problem that the sensitivity of an MEMS microphone cannot be highly consistent in the prior art.

According to an aspect of the present invention, there is provided a trimming method, including: obtaining an initial sensitivity of the MEMS microphone according to a first output signal provided by the MEMS microphone; selecting matched first data according to the initial sensitivity; and burning the first data into the MEMS microphone, wherein the gain value of the MEMS microphone is configured by the first data, so that the sensitivity of the MEMS microphone is configured within a preset range.

Preferably, the method further comprises the following steps: burning second data into the MEMS microphone, a bias voltage of the MEMS microphone configured by the second data; obtaining the sensitivity of the modified MEMS microphone according to a second output signal provided by the MEMS microphone; and sorting the MEMS microphones according to the trimmed sensitivities of the MEMS microphones, wherein the MEMS microphones provide the second output signal according to the bias voltage and the gain value.

Preferably, the preset range includes a plurality of preset intervals, and the step of sorting the MEMS microphones according to the trimmed sensitivities of the MEMS microphones includes: and sorting the MEMS microphones according to the preset interval corresponding to the sensitivity of the trimmed MEMS microphones.

Preferably, the method further comprises obtaining a look-up table of gain values of the MEMS microphone and first data, and the step of selecting the matching first data according to the initial sensitivity comprises: obtaining a plurality of theoretical sensitivities according to the sum of the initial sensitivities and each gain value in the comparison table; and calculating a difference value between each theoretical sensitivity and a target sensitivity so as to judge the theoretical sensitivity closest to the target sensitivity, and selecting the first data corresponding to the theoretical sensitivity, wherein the target sensitivity is within the preset range.

Preferably, the method further comprises the following steps: obtaining a comparison table of the gain value of the MEMS microphone and first data; and obtaining an initial gain value of the MEMS microphone, the step of selecting the matched first data according to the initial sensitivity comprising: calculating a difference between the initial sensitivity and the initial gain value so as to obtain the initial sensitivity after an initial gain is zeroed; obtaining a plurality of theoretical sensitivities according to the sum of the initial sensitivity after the initial gain is reset to zero and each gain value in the comparison table; and calculating a difference value between each theoretical sensitivity and a target sensitivity so as to judge the theoretical sensitivity closest to the target sensitivity, and selecting the first data corresponding to the theoretical sensitivity, wherein the target sensitivity is within the preset range.

According to another aspect of the present invention, there is provided a trimming apparatus comprising: the test module is used for obtaining the initial sensitivity of the MEMS microphone according to the first output signal provided by the MEMS microphone; and the control module is used for selecting matched first data according to the initial sensitivity and burning the first data into the MEMS microphone, wherein the gain value of the MEMS microphone is configured by the first data so that the sensitivity of the MEMS microphone is configured in a preset range.

Preferably, the MEMS microphone system further comprises a sorting module configured to sort the MEMS microphone according to the trimmed sensitivity of the MEMS microphone, wherein the control module is further configured to burn second data into the MEMS microphone, a bias voltage of the MEMS microphone is configured by the second data, and the MEMS microphone provides a second output signal according to the bias voltage and the gain value; the test module is further used for obtaining the sensitivity of the trimmed MEMS microphone according to the second output signal provided by the MEMS microphone.

Preferably, the preset range includes a plurality of preset intervals, and the control module is further configured to generate a corresponding sorting signal according to the preset interval corresponding to the trimmed sensitivity of the MEMS microphone, and send the sorting signal to the sorting module.

Preferably, the control module comprises: a storage unit for storing a plurality of first data and a look-up table of gain values of the MEMS microphone and the plurality of first data; the calculation unit is used for obtaining a plurality of theoretical sensitivities according to the sum of the initial sensitivity and each gain value in the comparison table, and calculating the difference value between each theoretical sensitivity and the target sensitivity; and the judging unit is used for judging the theoretical sensitivity closest to the target sensitivity according to the difference value of each theoretical sensitivity and the target sensitivity so as to select the first data corresponding to the theoretical sensitivity, wherein the target sensitivity is within the preset range.

Preferably, the control module comprises: a storage unit, configured to store an initial gain value of the MEMS microphone, and further configured to store a plurality of first data and a lookup table of the gain value of the MEMS microphone and the plurality of first data; a calculating unit, configured to calculate a difference between the initial sensitivity and the initial gain value, so as to obtain the initial sensitivity after the initial gain is zeroed, and further configured to obtain a plurality of theoretical sensitivities according to a sum of the initial sensitivity after the initial gain is zeroed and each gain value in the lookup table, and calculate a difference between each theoretical sensitivity and a target sensitivity; and the judging unit is used for judging the theoretical sensitivity closest to the target sensitivity according to the difference value of each theoretical sensitivity and the target sensitivity so as to select the first data corresponding to the theoretical sensitivity, wherein the target sensitivity is within the preset range.

According to the trimming method and the trimming device of the MEMS microphone, disclosed by the embodiment of the invention, the initial sensitivity of the MEMS microphone is detected, and the corresponding gain value is configured for the MEMS microphone according to the initial sensitivity, so that the sensitivity of the MEMS microphone is in a preset range. Compared with the prior art, the gain values corresponding to different MEMS microphones are configured, so that the sensitivity of all the MEMS microphones is in a preset range, and the sensitivity of all the modified MEMS microphones achieves the effect of high consistency.

Furthermore, the trimmed MEMS microphones are sorted by detecting the sensitivity of the trimmed MEMS microphones, so that the MEMS microphones can be more finely distinguished according to the sensitivity within a preset range.

Furthermore, by presetting a comparison table of the first data and the gain value, the gain value to be configured is directly selected according to the comparison table after the initial sensitivity of the MEMS microphone is obtained, and the first data is burned into the MEMS microphone, so that the trimming efficiency is greatly improved.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 shows a schematic structural diagram of a MEMS microphone according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram illustrating a trimming apparatus for a MEMS microphone according to an embodiment of the present invention.

Fig. 3 shows a flowchart of a trimming method of a MEMS microphone according to an embodiment of the present invention.

Detailed Description

The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. In addition, certain well known components may not be shown. For simplicity, the semiconductor structure obtained after several steps can be described in one figure.

It will be understood that when a layer or region is referred to as being "on" or "over" another layer or region in describing the structure of the device, it can be directly on the other layer or region or intervening layers or regions may also be present. And, if the device is turned over, that layer, region, or regions would be "under" or "beneath" another layer, region, or regions.

If for the purpose of describing the situation directly on another layer, another area, the expression "directly on … …" or "on … … and adjacent thereto" will be used herein.

In the following description, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.

The present invention may be embodied in various forms, some examples of which are described below.

As shown in fig. 1, the MEMS microphone 100 includes a MEMS sensor 110 and an ASIC chip 120. The ASIC chip 120 provides a bias voltage VBIAS to the MEMS sensor 110, the MEMS sensor 110 receives the bias voltage VBIAS and then generates a sensing signal in response to an external environment, and provides the sensing signal to the ASIC chip 120, and the ASIC chip 120 scales the sensing signal according to a configured gain value, and finally generates an output signal Vout.

As shown in fig. 2, the trimming apparatus 200 for a MEMS microphone includes: a control module 210, a testing module 220, and a sorting module 230. The control module 210 includes a configuration unit, a signal generation unit, a storage unit, a calculation unit, and a determination unit. In this embodiment, the control module 210 is implemented by, for example, upper computer test control software, the test module 220 is implemented by, for example, a MEMS microphone tester, and the sorting module 230 is implemented by, for example, a MEMS microphone sorter. However, the embodiments of the present invention are not limited thereto, and those skilled in the art may perform other arrangements on the implementation manner of each module as needed.

The trimming device 200 of the MEMS microphone provided in this embodiment is an automatic trimming device, and does not require human intervention during trimming. Hereinafter, the operation principle of the trimming apparatus 200 for a MEMS microphone will be described in detail with reference to fig. 3.

As shown in fig. 3, in step S01, a lookup table of gain values of the MEMS microphone and the first data is obtained.

In this embodiment, the target sensitivity of the MEMS microphone, a series of gain values, and first data corresponding to different gain values need to be determined in advance. When the initial sensitivity of the MEMS microphone is inconsistent with the target sensitivity, the sensitivity of the MEMS microphone can be adjusted to the target sensitivity by adjusting the gain value. In the actual tuning process, the sensitivity of the MEMS microphone approaches the target sensitivity within a certain range, and therefore a preset range needs to be set, and the target sensitivity is within the preset range.

TABLE 1 comparison Table of gain values of MEMS microphone and first data

First data	A	B	C	D	E	F	G	H	I	J
											Gain (dB)	0	0.5	-2.5	1.5	2	-1	-4.5	3.5	4	-3
First data	K	L	M	N	O	P	Q	R	S	T
											Gain (dB)	5	-0.5	2.5	-1.5	-2	1	4.5	-3.5	-4	3

As a specific example, the initial gain value of the MEMS microphone, the first data, the second data, and table 1 are stored in the storage unit of the control module 210, wherein table 1 lists the comparison relationship between the gain value of the MEMS microphone and the first data. In table 1, a total of 20 control groups are listed, each gain value has a uniquely determined first data corresponding to it, and the gain value of the MEMS microphone is configured by the first data. In table 1, the gain value range is between-4.5 dB and 5dB, and a gear is set every 0.5dB, wherein the gain value arrangement sequence in table 1 is not limited.

However, the embodiment of the present invention is not limited thereto, and a person skilled in the art may perform other settings on the comparison table of the gain value of the MEMS microphone and the first data according to actual needs, for example, the value range of the gain value, the number of comparison groups, and the like may be set according to actual products.

In a specific embodiment, for example, the target sensitivity S is set to-42 dB, and 0.5dB is added or subtracted based on the target sensitivity S, so that the preset range is-42 dB + -0.5 dB, i.e., -42.5dB to-41.5 dB, wherein the initial gain of the MEMS microphone is assumed to be 1 dB.

However, the embodiment of the present invention is not limited thereto, and those skilled in the art may set the target sensitivity S and the preset range width according to the actual product, for example, set the target sensitivity S to-40 dB, set the preset range to-40 dB ± 1dB, and the like. It should be noted that the initial gain of the MEMS microphone is an inherent characteristic of the ASIC chip, and can be referred to data provided by a factory manufacturer.

In step S02, the second data is burned into the MEMS microphone.

In this embodiment, the bias voltage VBIAS of the MEMS microphone is configured by the second data. The configuration unit of the control module 210 burns the second data into the ASIC chip 120 of the MEMS microphone. In this embodiment, the second data burned into each MEMS microphone is the same, so that the configured bias voltage VBIAS of each MEMS microphone is the same.

In step S03, an initial sensitivity of the MEMS microphone is obtained from the first output signal provided by the MEMS microphone.

In this step, the test module 220 obtains the initial sensitivity S1 of the MEMS microphone according to the first output signal, and then provides the initial sensitivity S1 to the control module 210. The MEMS microphone generates a first output signal according to the configured bias voltage VBIAS and the initial gain.

In some specific embodiments, the MEMS microphone is placed in a test environment, such as a 94dB sound pressure level (1Pa) environment, where a measurement of excitation is performed using a sound signal at a frequency of 1 kHz. The MEMS microphone provides a first output signal based on the bias voltage VBIAS and the initial gain, which is treated as a response of the MEMS microphone to a known sound pressure level, and the initial sensitivity S1 of the MEMS microphone is treated as a responsive capability to the known sound pressure level.

In step S04, the matching first data is selected according to the initial sensitivity.

In this step, the calculation unit of the control module 210 needs to calculate the difference between the initial sensitivity S1 and the initial gain in order to obtain the initial sensitivity after the initial gain is zeroed, then obtain a plurality of theoretical sensitivities S2 according to the sum of the initial sensitivity after the initial gain is zeroed and each gain value in the lookup table, respectively, and calculate the difference between each theoretical sensitivity S2 and the target sensitivity S. The judging unit of the control module 210 is configured to judge the theoretical sensitivity S2 closest to the target sensitivity S according to the difference between each theoretical sensitivity S2 and the target sensitivity S, so as to select the first data corresponding to the theoretical sensitivity S2.

In some specific embodiments, for example, it is detected that the initial sensitivity S1 of the MEMS microphone is-43.98 dB, the initial sensitivity after the initial gain is reduced to zero by 1dB is-44.98 dB, then-44.98 dB is sequentially summed with all the gain values in table 1, and when the gain value is 3, it is determined that the obtained theoretical sensitivity S2(-41.98dB) is closest to the target sensitivity S (-42dB), so the first data corresponding to the gain of 3dB is selected. After trimming, the sensitivity of the MEMS microphone should be-41.98 dB, within the preset range of-42 dB + -0.5 dB.

In some other embodiments, if the initial gain value of the MEMS microphone is 0, the step of returning the initial gain to zero may be omitted, and the calculating unit of the control module 210 may obtain the plurality of theoretical sensitivities directly according to the sum of the detected initial sensitivity S1 and each gain value in the look-up table.

However, the embodiment of the present invention is not limited thereto, and the initial gain value may also be negative, or the initial sensitivity is greater than the target sensitivity, for example, the initial gain is-0.5, the initial sensitivity is-40 dB, and the like, and the above-mentioned modification scheme of the present invention may also be applied.

In step S05, the first data is burned into the MEMS microphone.

In this step, the configuration unit of the control module 210 burns the first data selected in the last step into the ASIC chip 120 of the MEMS microphone, and the initial gain is replaced by the gain value configured by the first data. In some embodiments, the burning method is, for example, OTP burning, and the first data to be burned is an OTP burning code value "T". In a test environment, the MEMS microphone generates a second output signal according to the configured bias voltage VBIAS and the gain value. It should be noted that, before the OTP method is used to burn the first data into the ASIC chip 120, the content of the first data in the ASIC chip 120 is empty, so that the adjustable space of the gain value is large. In addition, the first data content being empty does not represent that the initial gain value of the ASIC chip 120 is zero, in other words, the initial gain value is not related to whether the first data content in the ASIC chip 120 is empty or not, because the initial gain value is an inherent characteristic of the ASIC chip.

In step S06, the sensitivity of the trimmed MEMS microphone is obtained according to the second output signal provided by the MEMS microphone.

In this step, the test module 220 obtains the sensitivity S3 of the trimmed MEMS microphone according to the second output signal, and then provides the sensitivity S3 to the control module 210. In this embodiment, the modified MEMS microphone generates the second output signal according to the configured bias voltage VBIAS and the gain value. The detection method of the sensitivity S3 is the same as the initial sensitivity S1, and is not described here again.

In step S07, the MEMS microphones are sorted according to the sensitivity of the trimmed MEMS microphones.

In this step, the signal generating unit of the control module 210 generates a corresponding sorting signal according to the preset interval corresponding to the sensitivity S3 and sends the sorting signal to the sorting module 230, so that the sorting module 230 sorts the modified MEMS microphones according to the sorting signal.

In some specific embodiments, when the preset range is-42 dB ± 0.5dB, the preset range may be divided into the following preset intervals: -42.5dB to-42.4 dB, -42.4dB to-42.3 dB, -42.3dB to-42.2 dB, -42.2dB to-42.1 dB, -42.1dB to-42.0 dB, -42.0dB to-41.9 dB, -41.9dB to-41.8 dB, -41.8dB to-41.7 dB, -43.7dB to-42.6 dB, and-41.6 dB to-41.5 dB. Wherein, the MEMS microphone with the sensitivity of-41.98 dB is sorted to the preset interval of-42.0 dB to-41.9 dB.

However, the embodiment of the present invention is not limited thereto, and those skilled in the art may perform other settings on the division of the preset interval according to actual needs.

In the above description, the technical details of patterning, etching, and the like of each layer are not described in detail. It will be appreciated by those skilled in the art that layers, regions, etc. of the desired shape may be formed by various technical means. In addition, in order to form the same structure, those skilled in the art can also design a method which is not exactly the same as the method described above. In addition, although the embodiments are described separately above, this does not mean that the measures in the embodiments cannot be used in advantageous combination.

The embodiments of the present invention have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the invention, and these alternatives and modifications are intended to fall within the scope of the invention.

Claims

1. a method for trimming MEMS microphone, is characterized in that, comprises:

obtaining the initial sensitivity of the MEMS microphone according to the first output signal provided by the MEMS microphone;

selecting matching first data based on the initial sensitivity; and

Burning the first data into the ASIC chip of the MEMS microphone, before burning the first data to the ASIC chip, the content of the first data in the ASIC chip is empty,

Wherein, the gain value of the MEMS microphone is configured by the first data, so that the sensitivity of the MEMS microphone is configured within a preset range.

2. trimming method according to claim 1, is characterized in that, also comprises:

programming second data to the MEMS microphone, the bias voltage of the MEMS microphone is configured by the second data;

obtaining the adjusted sensitivity of the MEMS microphone according to the second output signal provided by the MEMS microphone; and

Sorting the MEMS microphones according to the adjusted sensitivity of the MEMS microphones,

Wherein, the MEMS microphone provides the second output signal according to the bias voltage and the gain value.

3 . The adjustment method according to claim 2 , wherein the preset range includes a plurality of preset intervals, and the step of sorting the MEMS microphones according to the adjusted sensitivity of the MEMS microphones. 4 . The method includes: sorting the MEMS microphones according to the preset interval corresponding to the adjusted sensitivity of the MEMS microphones.

4. The trimming method according to any one of claims 1 to 3, further comprising obtaining a comparison table between the gain value of the MEMS microphone and the first data, and selecting a matching one according to the initial sensitivity The steps of the first data include:

Obtaining a plurality of theoretical sensitivities from the sum of the initial sensitivity and each gain value in the look-up table, respectively; and

calculating the difference between each of the theoretical sensitivity and the target sensitivity, so as to determine the theoretical sensitivity closest to the target sensitivity, and select the first data corresponding to the theoretical sensitivity,

Wherein, the target sensitivity is within the preset range.

5. The trimming method according to any one of claims 1 to 3, characterized in that, further comprising:

Obtaining a comparison table between the gain value of the MEMS microphone and the first data; and obtaining the initial gain value of the MEMS microphone, and the step of selecting the matching first data according to the initial sensitivity includes:

calculating the difference between the initial sensitivity and the initial gain value, so as to obtain the initial sensitivity after the initial gain is zeroed;

Obtaining a plurality of theoretical sensitivities according to the sum of the initial sensitivity after the initial gain is zeroed and each gain value in the comparison table; and

Wherein, the target sensitivity is within the preset range.

6. A trimming device for MEMS microphone, characterized in that, comprising:

a test module, configured to obtain the initial sensitivity of the MEMS microphone according to the first output signal provided by the MEMS microphone;

a control module, configured to select matching first data according to the initial sensitivity, and burn the first data into the ASIC chip of the MEMS microphone, and then burn the first data into the ASIC chip before, the first data content in the ASIC chip is empty,

7. The trimming device according to claim 6, further comprising a sorting module for sorting the MEMS microphones according to the sensitivity of the trimmed MEMS microphones,

Wherein, the control module is further configured to program second data to the MEMS microphone, the bias voltage of the MEMS microphone is configured by the second data, and the MEMS microphone is configured according to the bias voltage and the The gain value provides a second output signal; the test module is further configured to obtain the adjusted sensitivity of the MEMS microphone according to the second output signal provided by the MEMS microphone.

8 . The trimming device according to claim 7 , wherein the preset range includes a plurality of preset intervals, and the control module is further configured to adjust according to the adjusted sensitivity of the MEMS microphone. 9 . The preset interval generates a corresponding sorting signal and sends it to the sorting module.

9. The trimming device according to any one of claims 6-8, wherein the control module comprises:

a storage unit for storing a plurality of the first data and a comparison table of the gain value of the MEMS microphone and the plurality of the first data;

a calculation unit, configured to obtain a plurality of theoretical sensitivities according to the sum of the initial sensitivity and each gain value in the comparison table, and calculate the difference between each of the theoretical sensitivity and the target sensitivity; and

a judgment unit, configured to judge the theoretical sensitivity closest to the target sensitivity according to the difference between each of the theoretical sensitivity and the target sensitivity, so as to select the first data corresponding to the theoretical sensitivity,

Wherein, the target sensitivity is within the preset range.

10. The trimming device according to claim 9, wherein the control module comprises:

a storage unit, configured to store the initial gain value of the MEMS microphone, and also configured to store a plurality of the first data and a comparison table between the gain value of the MEMS microphone and the plurality of the first data;

A calculation unit, configured to calculate the difference between the initial sensitivity and the initial gain value, so as to obtain the initial sensitivity after the initial gain is reset to zero, and also configured to be respectively different from the initial sensitivity after the initial gain is reset to zero with the obtaining a plurality of theoretical sensitivities by summing each gain value in the said comparison table, and calculating the difference between each said theoretical sensitivity and the target sensitivity; and

Wherein, the target sensitivity is within the preset range.