CN103076051B - Silicon micro-flow-rate sensor chip in beam film four-beam structure - Google Patents

Abstract

The invention provides a silicon micro-flow-rate sensor chip in a beam film four-beam structure. The silicon micro-flow-rate sensor chip comprises a peripheral support silicon base, wherein a center silicon film is positioned in the middle of the peripheral support silicon base, the four edges of the center silicon film are connected with the peripheral support silicon base through four silicon cantilever beams, the middle of each silicon cantilever beam is provided with a pressure resistance strip, a Whetstone electric bridge is formed, when the fluid with the certain speed acts on the sensor chip, the inertia force can act on the center silicon film, further, the beam film structure deforms, the resistance value of the pressure resistance strip is changed under the stress effect of the silicon cantilever beams, the Whetstone electric bridge is out of balance, and an electric signal corresponding to the external flow rate is output, so the measurement of the sensor chip on the flow rate is realized. The silicon micro-flow-rate sensor chip has the advantages that the size is small, the weight is light, the response speed is high, and the sensitivity is high.

Description

A kind of beam film four girder construction silicon microflow sensor chip

Technical field

The invention belongs to micromechanics electronic technology field, be specifically related to a kind of beam film four girder construction silicon microflow sensor chip.

Background technology

Flow measurement is the important detected parameters of commercial production and research work.In recent years, along with to the further investigation of microelectromechanical systems (MEMS) and the progress that obtains, the flow sensor of traditional industry and fluid mechanics research is to high integration, microminiaturized, high precision, high reliability future development.MEMS flow sensor mainly can be divided into hot type and non-hot type two kinds by measuring principle, and through the development of 30 years, hot type MEMS flow sensor occupied the position of mainstream of flow measurement.But hot type microflow sensor also has its intrinsic shortcoming.Such as power consumption heat transfer that is large, substrate causes measuring error, zero point with environment temperature drift, response time length etc.In addition, because want convection cell to heat, so just limit the application of hot type microflow sensor in biotechnology.At present, the research of non-thermal flow rate sensor is relatively less, existing non-heat type flow quantity exist be difficult to take into account the sensitivity within the scope of gamut, general more difficult calculating, manufacture process be difficult to the problem such as compatible with standard CMOS process.

Summary of the invention

In order to overcome the shortcoming of above-mentioned prior art, the object of the present invention is to provide a kind of beam film four girder construction silicon microflow sensor chip, have volume little, weight is little, fast response time and highly sensitive advantage.

To achieve these goals, the technical solution used in the present invention is:

A kind of beam film four girder construction silicon microflow sensor chip, comprise peripheral support silica-based 3, glass substrate 4 is configured with at the back side of peripheral support silica-based 3, the back side of peripheral support silica-based 3 is carried out bonding with glass substrate 4 and is connected, central authorities' silicon fiml 1 is positioned at the centre of peripheral support silica-based 3, be connected by four silicon cantilevers 2 between four limits of central authorities' silicon fiml 1 and peripheral support silica-based 3, intermediate configurations on each silicon cantilever 2 has a pressure drag bar 5, four pressure drag bars 5 connect and compose Wheatstone bridge, the beam diaphragm structure that central authorities' silicon fiml 1 and silicon cantilever 2 form is sensor measurement position,

There is the gap of 350-370 μm between described central silicon fiml 1 and peripheral support silica-based 3 to make central matter silicon fiml 1 unsettled, and fluid can be made to pass through smoothly, the thickness of described central silicon fiml 1 is identical with the thickness of silicon cantilever 2;

Two axis of described central silicon fiml 1 overlap with two axis of peripheral support silica-based 3, and overlap with the axis of two silicon cantilevers 2 respectively.

Described silicon cantilever 2 have employed (100) crystal face silicon, in crossing distribution.

Four described pressure drag bars 5 along [110] and $\left[\begin{array}{ccc}1& \stackrel{\‾}{1}& 0\end{array}\right]$ Crystal orientation is arranged.

The present invention adopts 250um(100 crystal face) N-type twin polishing silicon chip.

Because the present invention adopts the structure of cantilever beam as sensitive element, integrate and add traffic aware and metering circuit, adopt 250um(100 crystal face simultaneously) N-type twin polishing silicon wafer to manufacture, so it is little to have volume, weight is little, fast response time and highly sensitive advantage.

Accompanying drawing explanation

Fig. 1 is structural representation of the present invention.

Fig. 2 is schematic cross-section of the present invention.

Fig. 3 is the distribution schematic diagram of pressure drag bar 5 on silicon cantilever 2.

Fig. 4 is the Wheatstone bridge schematic diagram that pressure drag bar 5 is formed.

Embodiment

Below in conjunction with accompanying drawing, structure & working mechanism of the present invention is described in detail.

See Fig. 1 and 2, a kind of beam film four girder construction silicon microflow sensor chip, comprise peripheral support silica-based 3, glass substrate 4 is configured with at the back side of peripheral support silica-based 3, the back side of peripheral support silica-based 3 is carried out bonding with glass substrate 4 and is connected, central authorities' silicon fiml 1 is positioned at the centre of peripheral support silica-based 3, be connected by four silicon cantilevers 2 between central authorities' silicon fiml 1 and peripheral support silica-based 3, intermediate configurations on each silicon cantilever 2 has a pressure drag bar 5, four pressure drag bars 5 connect and compose Wheatstone bridge, the beam diaphragm structure that central authorities' silicon fiml 1 and silicon cantilever 2 form is sensor measurement position, the metering circuit that the flow signal input that sensor chip senses consists of four pressure drag bars 5 is finally converted into electric signal, complete the induction to flow and measurement.

The gap of 350-370 μm is there is to make central silicon fiml 1 unsettled between described central silicon fiml 1 and peripheral support silica-based 3, and fluid can be passed through, certain displacement can be there is in central authorities' silicon fiml 1 when extraneous flow effect, thus perceived flux information, the thickness of described central silicon fiml 1 is identical with the thickness of silicon cantilever 2, the width of silicon cantilever 2 is less than the width of 1 of central silicon fiml, makes stress concentrate effect obviously.

Two axis of described central silicon fiml 1 overlap with two axis of peripheral support silica-based 3, and overlap with the axis of two silicon cantilevers 2 respectively.

Described silicon cantilever 2 have employed (100) crystal face silicon, in crossing distribution.

Four described pressure drag bars 5 along [110] and $\left[\begin{array}{ccc}1& \stackrel{\‾}{1}& 0\end{array}\right]$ Crystal orientation is arranged.

The present invention adopts 250um(100 crystal face) N-type twin polishing silicon chip.

See Fig. 3 and Fig. 4, four pressure drag bars 5 are respectively resistance R1, R2, R3 and R4, and on four silicon cantilevers 2, resistance R1 and resistance R3 layout in alignment, resistance R2 and resistance R4 is that straight line is arranged, four pressure drag bars 5 connect and compose Wheatstone bridge.

Principle of work of the present invention is:

When certain speed fluid orthogonal acts on sensor chip upper surface, central silicon fiml 1 is as the sensitive diaphragm of sensor flow.According to Bernoulli equation, when certain speed fluid matasomatism is in central silicon silicon fiml 1, due to the effect of inertial force, central authorities' silicon fiml 1 can produce certain displacement, and then the silicon cantilever 2 part generation deformation making in beam diaphragm structure, the stress that this deformation produces causes the resistance change of the pressure drag bar 5 be distributed on silicon cantilever 2.This change in resistance changes electric signal into by Wheatstone bridge and exports, thus realizes the flow-voltage signal conversion of sensor chip, completes the measurement to flow.

The variable quantity of pressure drag bar 5 resistance in the present invention on silicon cantilever 2 is calculated by the correlation formula of piezoresistive effect, and piezoresistive effect refers to when semiconductor material is subject to effect of stress, due to the change of carrier mobility, makes the phenomenon that its resistivity changes.When pressure drag bar is under certain effect of stress, its change in resistance and the scale relation suffered by it between stress as follows:

$\frac{\mathrm{\ΔR}}{R}={\mathrm{\π}}_l{\mathrm{\σ}}_i+{\mathrm{\π}}_{\mathrm{\τ}}{\mathrm{\τ}}_i$

In formula: R---the initial resistance of pressure drag bar;

π _l---be the horizontal piezoresistance coefficient of pressure drag bar;

π _τ---the longitudinal piezoresistance coefficient of pressure drag bar;

σ _i---the normal stress that pressure drag bar is subject to;

τ _i---the shear stress that pressure drag bar is subject to.

Therefore the stress that silicon cantilever 2 produces when extraneous flow effect will make the change in resistance of the pressure drag bar 5 on it, by Wheatstone bridge by this change transitions be again electric signal export, then the induction to flow and measurement is realized, piezoresistive effect has anisotropic feature, apply stress along different directions or pass through electric current along different directions, the change in resistance of material is all not identical, in order to obtain larger output electric signal under same flow effect, silicon cantilever 2 in the present invention selects (100) crystal face silicon chip, utilize (100) crystal face silicon in [110] and $\left[\begin{array}{ccc}1& \stackrel{\‾}{1}& 0\end{array}\right]$ Crystal orientation has maximal value, feature almost nil on [100] and [010] crystal orientation, pressure drag bar 5 along [110] and $\left[\begin{array}{ccc}1& \stackrel{\‾}{1}& 0\end{array}\right]$ Crystal orientation distributes, and improves the measuring accuracy of sensor chip to flow.

Claims (1)

1. a beam film four girder construction silicon microflow sensor chip, comprise peripheral support silica-based (3), it is characterized in that: be configured with glass substrate (4) at the back side of peripheral support silica-based (3), the back side of peripheral support silica-based (3) is carried out bonding with glass substrate (4) and is connected, central authorities' silicon fiml (1) are positioned at the centre of peripheral support silica-based (3), be connected by four silicon cantilevers (2) between four limits of central authorities' silicon fiml (1) and peripheral support silica-based (3), intermediate configurations on each silicon cantilever (2) has a pressure drag bar (5), four pressure drag bars (5) connect and compose Wheatstone bridge, the beam diaphragm structure that central authorities' silicon fiml (1) and silicon cantilever (2) form is sensor measurement position,

The gap of 350-370 μm is there is to make central silicon fiml (1) unsettled between described central silicon fiml (1) and peripheral support silica-based (3), and fluid can be made to pass through smoothly, and the thickness of described central silicon fiml (1) is identical with the thickness of silicon cantilever (2);

Two axis of two axis silica-based with peripheral support (3) of described central silicon fiml (1) overlap, and overlap with the axis of corresponding two silicon cantilevers (2) respectively;

Described silicon cantilever (2) have employed (100) crystal face silicon, in crossing distribution;

Four described pressure drag bars (5) along [110] and crystal orientation is arranged.