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Microacoustic device based on clamped diaphragm structure and mfg. method thereof

A membrane structure and device technology, which is applied to the fixing/tensioning of the diaphragm, diaphragm structure, sensors, etc., can solve the problems of device function failure, high requirements, and low tape-out yield, and achieve electrical and mechanical performance The effect of stability, firm structure and high yield

Inactive Publication Date: 2006-11-01
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, its manufacturing process is relatively complicated, and the process of releasing the cantilever has high requirements for micromachining equipment; in addition, the device adopts the surface silicon micromachining method and the bulk silicon micromachining method compatible with the traditional IC process. The composite film is prepared under the process conditions of growth, deposition, etching, etc., and residual stress will inevitably be generated in the film. Under normal circumstances, the thermally grown silicon oxide will exhibit a compressive stress of about 300MPa. Sol-gel The lead zirconate titanate ferroelectric film prepared by the method generally exhibits a tensile stress of about 180 MPa after polarization, and the silicon nitride deposited by the low-stress low-pressure chemical vapor deposition method exhibits a tensile stress of about 200 MPa. The metal formed by sputtering The platinum electrode exhibits a tensile stress of about 800 MPa, compared with the internal stress of other layers can be ignored
These residual stresses will accumulate during the formation of the microstructure, which will have a great impact on the mechanical properties of the device, and even cause the function of the device to fail after the structure is released.
Due to the stress stiffening effect, that is, the coupling effect of in-plane stress and transverse stiffness, it will also greatly affect the mechanical sensitivity of the microstructure.
Under the influence of the residual stress of the film, the initial disturbance of the cantilever diaphragm structure is too large, which will reduce the sensitivity of the device, and even cause the destruction of the device structure itself, resulting in a low yield of tape-out

Method used

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  • Microacoustic device based on clamped diaphragm structure and mfg. method thereof
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  • Microacoustic device based on clamped diaphragm structure and mfg. method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0055] Preparation of composite film Al / SiO 2 / Pt / PZT / Pt / Ti / SiO 2 / Si 3 N 4 / SiO 2 The thickness of each layer of / Si is 800 / 300 / 150 / 1000 / 200 / 20 / 100 / 200 / 900 / 10 nanometers, and the diaphragm structure is 2500 microns × 2500 microns.

[0056] (a) Use a P-type silicon wafer with a diameter of 3 inches and a thickness of 400 ± 10 microns and double-sided polishing as a substrate (the substrate resistivity is 1-10Ω·cm), boil it with a mixture of concentrated sulfuric acid and hydrogen peroxide for 10 Minutes, then rinsed with deionized water and dried; put the silicon wafer into an oxidation furnace, and thermally grow a 900-nanometer silicon dioxide layer on both sides of the silicon wafer at 1050±1°C;

[0057] (b) Using the low-pressure chemical vapor deposition method, a silicon nitride layer with a thickness of 200 nanometers is formed on both sides of the silicon wafer, and the silicon nitride layer on the back is etched by reactive ion etching to form a back cavity window...

Embodiment 2

[0068] Preparation of composite film Al / SiO 2 / Pt / PZT / Pt / Ti / SiO 2 / Si 3 N 4 / SiO 2 The thickness of each layer of / Si is 400 / 200 / 150 / 400 / 150 / 20 / 100 / 200 / 800 / 2 nanometers, respectively, with a clamped diaphragm structure, and the diaphragm size is 500 microns × 500 microns.

[0069] (a) Use a P-type silicon wafer with a diameter of 3 inches and a thickness of 400 ± 10 microns and double-sided polishing as a substrate (the substrate resistivity is 1-10Ω·cm), boil it with a mixture of concentrated sulfuric acid and hydrogen peroxide for 10 Minutes, then rinse and dry with deionized water; put the silicon wafer into an oxidation furnace, and thermally grow 800nm ​​silicon dioxide layers on both sides of the silicon wafer at 1050±1°C;

[0070] (b) Using the low-pressure chemical vapor deposition method, a silicon nitride layer with a thickness of 200 nanometers is formed on both sides of the silicon wafer, and the silicon nitride layer on the back is etched by reactive ion etchi...

Embodiment 3

[0081] Preparation of composite film Al / SiO 2 / Pt / PZT / Pt / Ti / SiO 2 / Si 3 N 4 / SiO 2 The thickness of each layer of / Si is 1000 / 300 / 200 / 800 / 200 / 30 / 150 / 150 / 1000 / 20 nanometers, and the diaphragm structure is 3000 microns × 3000 microns.

[0082] (a) With a diameter of 3 inches, a thickness of 400 ± 10 microns, double-sided polished N-type silicon wafer as a substrate (substrate resistivity 1-10Ω cm), boiled with a mixture of concentrated sulfuric acid and hydrogen peroxide for 10 Minutes, then rinse and dry with deionized water; put the silicon wafer into an oxidation furnace, and thermally grow a 1000-nanometer silicon dioxide layer on both sides of the silicon wafer at 1050 ° C ± 1;

[0083] (b) Using the low-pressure chemical vapor deposition method, a silicon nitride layer with a thickness of 150 nanometers is formed on both sides of the silicon wafer, and the silicon nitride layer on the back is etched by reactive ion etching to form a back cavity window, and then the sil...

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Abstract

A micro-acoustic device based on a clamped diaphragm structure and a manufacturing method thereof, relating to the structural design of a micro-acoustic device. The device is composed of a silicon substrate and a composite film arranged on it. The composite film is composed of a silicon layer, a thermal oxygen layer, a silicon nitride layer, a low-temperature deposited silicon dioxide layer, and a metal titanium adhesive. Adhesive layer, metal platinum lower electrode layer, lead zirconate titanate ferroelectric thin film layer, metal platinum upper electrode layer, silicon dioxide layer deposited by plasma chemical vapor deposition, metal aluminum lead layer, and the surrounding of the composite film is solidified with the silicon substrate tied together. Because the present invention adopts the diaphragm structure clamped around and optimizes the size of the film layer, it effectively overcomes the defects of the cantilever diaphragm structure of the micro-acoustic device, and has the outstanding features of firm structure, reliable performance and high yield features. Tests show that its acoustic sensitivity is on the order of 10mV / Pa, which can meet the needs of audio applications in mobile phones, hearing aids and other digital communication systems.

Description

technical field [0001] The invention relates to a micro-acoustic device and a manufacturing method thereof, in particular to a structural design and a manufacturing method of a micro-acoustic device for a micro-acoustic device with a diaphragm structure clamped around a micro-microphone and a loudspeaker. Background technique [0002] In recent years, MEMS (Micro-Electro-Mechanical System) technology has developed rapidly. Currently, MEMS products that have entered the market include various pressure sensors and accelerometers for automotive airbag control. In the application field of MEMS, the research and development of micro-acoustic devices has increasingly become one of the focuses of people's attention. Taking the micro-microphone as an example, it can be applied to cellular phones, cordless phones, hearing aids, various digital multimedia devices, acoustic monitoring systems, and so on. Compared with traditional acoustic devices, MEMS micro-acoustic devices have the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04R7/02H04R7/16H04R31/00
Inventor 任天令刘理天杨轶张林涛
Owner TSINGHUA UNIV