CN2704174Y

CN2704174Y - Micro acoustic device based on magneto resistance effect

Info

Publication number: CN2704174Y
Application number: CN 200420049609
Authority: CN
Inventors: 任天令; 刘理天; 欧阳可青; 朱一平
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2004-04-26
Filing date: 2004-04-26
Publication date: 2005-06-08
Anticipated expiration: 2014-04-26

Abstract

The utility model discloses a micro acoustic device based on magneto resistance effect, which belongs to the field of semiconductor device. The device is composed of a structure of movable diaphragm with hard magnetic thin film as the sediment and a fixed structure of multilayer film of magneto resistor as the sediment. The structure of movable diaphragm is successively combined by silicon bulk, silicon dioxide, layer of silicon nitride and layer of silicon dioxide from the substratum to the upper position. The structure of the fixed part is the same as the structure of the movable diaphragm, except that the layer of permanent magnet material is changed into the GMR multilayer film of magneto resistor. The utility model makes use of the movable diaphragm and multilayer film of magneto resistor to realize the transmission between the signals of electricity and sound, which makes the kind of acoustical device with high sensibility, low noise, and broad range of response available. The subsequent processing circuit is very simple. Because of the simple processing steps, the performance of the product is reliable, the rate of finished products is high and the device can meet the requirements of the volume-production.

Description

Micro-acoustic device based on magneto-resistance effect

Technical field

The utility model belongs to field of semiconductor devices, particularly a kind of micro-acoustic device based on magneto-resistance effect.

Background technology

Magneto-resistor MR (magnetoresistance) effect is meant the material phenomenon that resistance changes under the action of a magnetic field.Ferromagnetic multicrystal anisotropic magnetoresistance (AMR) effect promptly was found as far back as 1857, because sensitivity is not high, and had limited its application in sensor field.The discovery of giant magnetoresistance effect (GMR), tunneling magnetoresistance (TMR) and huge magneto-resistance effect (CMR) after 1988 in the metallized multilayer film has activated this field.Magnetic resistance material can be made various highly sensitive Magnetic Sensors, and the Weak magentic-field signal is surveyed.Compared with various traditional transducers, the superiority of MR transducer is very outstanding: volume is little, highly sensitive, impedance is low, anti-adverse environment, cost of manufacture is low, response range is wide, temperature coefficient of resistance is little, and can realize contactless detection.Because the MR transducer is mainly surveyed the angle of the two magnetospheric direction of magnetizations, thus not high to the requirement of strength in detection magnetic field, on the making precision of transducer itself, also can allow relatively large error.Now, the GMR sensing technology has broad application prospects in fields such as automatic technology, household electrical appliance, brand recognition, satellite fix, navigation system and Technologies of Precision Measurement.

On the other hand, MEMS (Micro-Electro-Mechanical System) technology obtains develop rapidly in recent years, and has obtained immense success.Not only volume is little, cost is low, mechanical property is good to use the microsensor that MEMS technology makes, and can be integrated with cmos circuit, forms complicated micro-system, and silicon-based micro-microphone is exactly a focus of microsensor area research in recent years.With the micro-microphone is example, and it can be applied to cell phone, cordless telephone, hearing aids, various digital multimedia device, acoustic monitoring system or the like.Compare with traditional acoustical device, the MEMS micro-acoustic device have that volume is little, cost is low, reliability is high and can with the mutually integrated characteristics of signal processing circuit, thereby have wide application and fabulous application prospect.

Present silica-based micro-acoustic device, mainly based on electric capacity, piezoelectricity, pressure drag, modulation field effect transistor, optical waveguide principle, wherein piezoelectric type and condenser type are topmost two kinds.The advantage of piezoelectric type silicon micro-microphone is not have the air gap damping, need not bias voltage, but its sensitivity is generally lower, and noise is higher relatively.And Electret Condencer Microphone has superiority at aspects such as sensitivity, frequency response, temperature stabilities.Chinese invention patent (application number: 01140441.8) proposed a kind of design and manufacture craft thereof of line membrane capacitance formula silica-based microphone, utilize the line membrane structure to reduce of the influence of the interior residual stress of film to microphone property, be expected to obtain reasonable device performance, but its preparation process is very complicated, need bulk silicon technological and sacrifice layer process to combine, reliability and rate of finished products all are very limited.

Summary of the invention

The purpose of this utility model is to propose magneto-resistance effect a kind of micro-acoustic device based on magneto-resistance effect that combines with the MEMS technology is made of with the standing part that deposits magnetoresistive multilayered film the movable diaphragm part that deposits permanent thin film.It is characterized in that: the structure of described movable diaphragm part is for upwards being that silicon substrate 8, thermal oxidation silicon dioxide 7, silicon nitride layer 6, thermal oxidation silicon dioxide 7, low-temperature epitaxy silicon dioxide 9, permanent magnet material layer 11 and enhancing silicon dioxide layer 12 are formed composite membrane and stretched from silicon substrate 8 and form the cantilever diaphragm structure successively by bottom; The structure of described standing part is identical with the movable diaphragm part, just changes permanent magnet material layer 11 into GMR magnetoresistive multilayered film 10; Between cantilever vibrating diaphragm and standing part, erode away a fault trough 13; Deposit thermal oxidation silicon dioxide 7 and silicon nitride layer 6 successively at two-part silicon substrate 8 back sides, chamber 14 is carried on the back at the two-part back side in addition.

Described GMR magnetoresistive multilayered film is followed successively by tantalum layer 1, nifesphere 2, cobalt iron layer 3, copper layer 3, cobalt iron layer 3, iridium manganese layer 5 and tantalum layer 1 from bottom to top.

Described permanent magnet material layer is the cobalt chromium tantalum hard magnetic layer of magnetron sputtering deposition.

Compare with micro-acoustic devices such as existing piezoelectric type, condenser types, the beneficial effects of the utility model are that the utility model and MEMS process technology combine magneto-resistance effect is applied to micro-acoustic device, have realized the acoustoelectric signal conversion.Because the advantageous characteristic of the MR element that adopts, can realize effective detection of acoustic vibration, thereby obtain high sensitivity, low noise, the wide micro-acoustic device of response range, on mobile phone, hearing aids and other communication system voice applications, all have vast market prospect.Simultaneously, because what obtain is the resistance variations signal, do not need the charge detector in the micro-acoustic device of condenser type or piezoelectric type, subsequent conditioning circuit is handled simple, is not subject to influences such as temperature, humidity simultaneously, is beneficial to production in enormous quantities.

Description of drawings

Fig. 1 is the structural representation of magnetoresistive multilayered film

Fig. 2 is the structural representation of the acoustical device of cantilever type diaphragm structure.

Fig. 3 is the vertical view of Fig. 2.

Embodiment

The utility model proposes a kind of micro-acoustic device that magneto-resistance effect is combined with the MEMS technology based on magneto-resistance effect.Constitute with the standing part that deposits magnetoresistive multilayered film by the movable diaphragm part that deposits permanent thin film.In Fig. 2, structure shown in Figure 3, the structure of left side movable diaphragm part is for upwards being that silicon substrate 8, thermal oxidation silicon dioxide 7, silicon nitride layer 6, thermal oxidation silicon dioxide 7, low-temperature epitaxy silicon dioxide 9, permanent magnet material layer 11 and enhancing silicon dioxide layer 12 are formed composite membrane and stretched from silicon substrate 8 and form the cantilever diaphragm structure successively by bottom; The structure of the right standing part is identical with the movable diaphragm part, just changes permanent magnet material layer 11 into GMR magnetoresistive multilayered film 10; Between cantilever vibrating diaphragm and standing part, erode away a fault trough 13; Deposit thermal oxidation silicon dioxide 7 and silicon nitride layer 6 successively at two-part silicon substrate 8 back sides, chamber 14 is carried on the back at the two-part back side in addition.

Wherein GMR magnetoresistive multilayered film 10 (as shown in Figure 1) is followed successively by tantalum layer 1, nifesphere 2, cobalt iron layer 3, copper layer 4, cobalt iron layer 3, iridium manganese layer 5 and tantalum layer 1 from bottom to top.Wherein permanent magnet material layer 11 is the cobalt chromium tantalum hard magnetic layer of magnetron sputtering deposition.

The principle of the utility model foundation is: extraneous acoustic pressure causes that movable diaphragm vibrates, cause the permanent thin film that deposits on the movable diaphragm to produce the variation in magnetic field, this changes the magnetoresistive multilayered film that deposits and surveys on fixed structure, the multilayer film changes in resistance that causes can be read by external circuit, thereby realizes the conversion of signals of acoustic-electric.

Claims

1. the micro-acoustic device based on magneto-resistance effect is made of with the standing part that deposits magnetoresistive multilayered film the movable diaphragm part that deposits permanent thin film the micro-acoustic device based on magneto-resistance effect; It is characterized in that: described movable diaphragm structure is for upwards being that silicon substrate (8), thermal oxidation silicon dioxide (7), silicon nitride layer (6), thermal oxidation silicon dioxide (7), low-temperature epitaxy silicon dioxide (9), permanent magnet material layer (11) and enhancing silicon dioxide layer (12) are formed composite membrane and stretched from silicon substrate (8) and form the cantilever diaphragm structure successively by bottom; The structure of described standing part is identical with the movable diaphragm part, just changes permanent magnet material layer (11) into GMR magnetoresistive multilayered film (10); Between cantilever vibrating diaphragm and standing part, erode away a fault trough (13); Deposit the silicon dioxide (7) and the silicon nitride layer (6) of thermal oxidation successively at two-part silicon substrate (8) back side, chamber (14) is carried on the back at the two-part back side in addition.

2. according to the described micro-acoustic device based on magneto-resistance effect of claim 1, it is characterized in that: described GMR magnetoresistive multilayered film is followed successively by tantalum layer (1), nifesphere (2), cobalt iron layer (3), copper layer (4), cobalt iron layer (3), iridium manganese layer (5) and tantalum layer (1) from bottom to top.

3. according to the described micro-acoustic device based on magneto-resistance effect of claim 1, it is characterized in that: described permanent magnet material layer is the cobalt chromium tantalum hard magnetic layer of magnetron sputtering deposition.