MEMS microphone

The present invention provides a MEMS microphone, having a base and a capacitive system provided on the base. The capacitive system includes a diaphragm and a back plate. The MEMS microphone is further provided with a supporting frame located between the back plate and the diaphragm. One end of the supporting frame is connected with the back plate, and the other end is connected with the diaphragm. The supporting frame divides the cavity into a first cavity body and a second cavity body. The supporting frame is provided with a connection channel. During the production process of the MEMS microphone, the etchant enters the first cavity body, and then enters the second cavity body, which prevents oxides from remaining in the microphone product and affecting the use of MEMS microphone.

FIELD OF THE PRESENT DISCLOSURE

The present invention relates to a microphone in particular to a MEMS microphone.

DESCRIPTION OF RELATED ART

The MEMS microphone generally comprises a base and a capacitive system provided on the base. The capacitive system comprises a diaphragm and a back plate that is disposed at a distance from the diaphragm and forms a cavity with the diaphragm. When the MEMS microphone is powered and working, the diaphragm and the back plate respectively carry charges of opposite polarity. At the same time, a supporting frame is provided between the back plate and the diaphragm to support the back plate. Due to the existence of the supporting frame, the supporting frame divides the cavity formed between the back plate and the diaphragm into a second cavity body located on the edge and a first cavity body located in the middle. During the production process of MEMS microphones, first, the oxide material is injected into the cavity formed between the back plate and the diaphragm, and then an etchant is injected through the amplification hole on the back plate into the cavity so that the oxide in the cavity is corroded. But due to the existence of the supporting frame, the etchant can only erode the oxide material in the first cavity body in the middle, but cannot erode the oxide in the second cavity body on the edge so the oxide remains in the microphone product and affects the use of MEMS microphone.

SUMMARY OF THE PRESENT INVENTION

One of the objects of the present invention is to provide a MEMS microphone which is enable to prevent oxides from remaining in the microphone.

For achieving the object, the present invention provides a MEMS microphone including a base comprising a back cavity;

a capacitive system provided on the base, the capacitive system including a diaphragm and a back plate arranged spaced from the diaphragm and forming a cavity with the diaphragm;

a supporting frame located between the back plate and the diaphragm, one end of the supporting frame being connected with the back plate, and the other end being connected with the diaphragm; wherein

the supporting frame divides the cavity into a first cavity body located in a middle thereof and a second cavity body surrounding the first cavity body; the supporting frame is provided with a connection channel connecting the first cavity body and the second cavity body.

Further, the supporting frame is a hollow circular structure.

Further, the supporting frame is provided with through holes, and the through hole connects the first cavity body with the second cavity body.

Further, the supporting frame comprises a plurality of supporting cylinders, a gap is formed between adjacent supporting cylinders, for connecting the first cavity body and the second cavity body.

Further, a cross section of the supporting cylinder is a square, a circle, a triangle, or a hexagon.

Further, the supporting frame comprises a supporting cylinder array arranged on edge of a circle, the supporting cylinder array comprises a plurality of supporting cylinders, and in the supporting cylinder array, the gap is formed between adjacent supporting cylinders.

Further, the supporting frame comprises n+1 supporting cylinder arrays arranged on edge of a circle with interval, the i+1th supporting cylinder array is arranged around the ith supporting cylinder; wherein n is a natural number greater than or equal to 1, and the range of i is [1, n].

Further, the supporting frame is made of conductive material.

Further, the supporting frame is made of insulating material.

Further, the diaphragm is arranged above the base and spaced from the base, and the back plate is arranged above the diaphragm.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The present disclosure will hereinafter be described in detail with reference to an exemplary embodiment. To make the technical problems to be solved, technical solutions and beneficial effects of the present disclosure more apparent, the present disclosure is described in further detail together with the figure and the embodiment. It should be understood the specific embodiment described hereby is only to explain the disclosure, not intended to limit the disclosure.

As shown inFIGS. 1-3, the present invention provides a MEMS microphone which comprises a base1having a back cavity7and a capacitive system disposed on the base1.

The capacitive system comprises a diaphragm2and a back plate3which is spaced from the diaphragm2and forms a cavity with the diaphragm2. When the MEMS microphone is powered and working, the diaphragm2and back plate3respectively have charges of opposite polarity and form a capacitive system. At this time, when the sound wave reaches diaphragm2from back cavity7, the diaphragm2vibrates under the influence of sound wave which causes the spacing distance between diaphragm2and back plate3change and further causes the capacitance in the capacitive system change so as to achieve the conversion from acoustic wave into electrical signal and realize the corresponding functions of the MEMS microphone.

Further, a supporting frame5is provided between the diaphragm2and the back plate3. One end of the supporting frame5is connected with the back plate3and the other end is connected with the diaphragm2. The supporting frame5divides the cavity formed between the back plate3and the diaphragm2into a first cavity body4in the middle and a second cavity body6in the periphery.

In order to ensure that during the production of MEMS microphone, the oxide in the second cavity body6located in the periphery is removed to avoid remaining in the MEMS microphone products, in the present invention, a connection channel is set in the supporting frame5, the connection channel can connect the first cavity body4with the second cavity body6.

Preferably, the supporting frame5is a hollow circular structure.

As shown inFIG. 2, through holes53are provided on the supporting frame5, and the through hole53connect the first cavity body4with the second cavity body6.

Further, the supporting frame5comprises multiple supporting cylinders51, a gap52is formed between the adjacent supporting cylinders51, the gap52is a connection channel connecting the first cavity body4with the second cavity body6.

Further, the cross section of the supporting cylinder51is other shapes such as a square, a circle, a triangle, or a hexagon.

Further, according to different arrangements of multiple supporting cylinders51, the supporting frame5further comprises one or multiple supporting cylinder arrays arranged on edge of a circle.

Wherein, each supporting cylinder array comprises multiple supporting cylinders51, a gap52is formed between the adjacent supporting cylinders51in each supporting cylinder array.

Preferably, when the supporting frame5comprises multiple supporting cylinder arrays, multiple supporting cylinder arrays are arranged with interval on edge of a circle. The supporting cylinder array of adjacent circles is arranged on edge of a circle.

That is, when the supporting frame5comprises n+1 supporting cylinder arrays arranged with interval on edge of a circle, the i+1th supporting cylinder array is arranged around the ith supporting cylinder array, where n is a natural number greater than or equal to 1, and the range of i is [1, n].

For example, as shown inFIG. 3the supporting frame5comprises two supporting cylinder arrays, which are respectively recorded as a first supporting cylinder array and a second supporting cylinder array. The first supporting cylinder array surrounds the second supporting cylinder array.

Further, the supporting cylinder51is made of conductive material or insulating material.

Preferably, as shown inFIGS. 1 and 2, the back plate3of the MEMS microphone in this embodiment further comprises a first insulation layer32, an electrode layer33, and a second insulation layer34which are sequentially stacked. The second insulation layer34is arranged opposite to the diaphragm.

Wherein, the electrode layer33is arranged between the first insulation layer32and the second insulation layer34to avoid a situation where a short-circuit occurs due to the contact between the diaphragm2and the electrode layer33of the back plate3during the diaphragm vibration of diaphragm2.

Preferably, the periphery of the first insulation layer32is in a stair shape and is connected with the base1.

Preferably, the back plate3is further provided with a metal layer31covering the periphery of the first insulation layer32

In the MEMS microphone in this embodiment, diaphragm2is arranged between the back plate3and the base1, and a cavity is formed between the diaphragm2and the back plate3. The diaphragm2is arranged above the base1and is spaced from the base1. In general, the base1of the MEMS microphone is a circular structure, and the corresponding diaphragm2is also a circular structure.FIG. 1orFIG. 2in this embodiment only shows a vertical cross sectional structure view of vertical view of the MEMS microphone.

The present invention is improved by the supporting frame5provided between diaphragm2and back plate3, and a connection channel connecting the first cavity body4and the second cavity body6is arranged on the supporting frame5so that during the production process of the product, the etchant etc. can enter the second cavity body6from the first cavity body4to corrode the oxide in the second cavity body6and completely remove the oxide in the second cavity body6, which prevent oxides from remaining in MEMS microphone products and affecting the use of microphones.

Besides, the present invention only improves the supporting frame5and does not remove the supporting frame5and also guarantees the intensity of the back plate3.

In addition, the improvement of the supporting frame5in the present invention does not change due to position change of the diaphragm2and the back plate3. The back plate3shown inFIG. 1in the present embodiment is arranged above the diaphragm2. And when the back plate3is under the diaphragm2, the structure of the supporting frame5is also applicable.

What have been described above are only the embodiments of the present invention. It should be pointed out that for those skilled in the art, improvements can be made without departing from the inventive concept of the present invention which is also in protection scope of the present invention.