CN103076051A - 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 chips

Technical field

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

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, microminiaturization, high precision, high reliability future development.The MEMS flow sensor mainly can be divided into two kinds of hot type and non-hot types by measuring principle, and through the development in 30 years, hot type MEMS flow sensor occupied the position of mainstream of flow measurement.But the hot type microflow sensor also has its intrinsic shortcoming.Heat large such as power consumption, substrate causes measuring error, zero point with environment temperature drift, response time length etc.In addition, because want the convection cell heating, so just limited the application of hot type microflow sensor aspect biotechnology.At present, the research of non-thermal flow rate sensor is relatively less, and there is the sensitivity that is difficult to take into account in the gamut scope in existing non-heat type flow quantity, generally difficultly calculates, manufacture process is difficult to and the problem such as standard CMOS process compatibility.

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 chips, have a 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 chips, comprise peripheral support silica-based 3, support silica-based 3 the back side in the periphery and dispose glass substrate 4, 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 peripheral silica-based 3 the centre of supporting, link to each other by four silicon cantilevers 2 between four limits of central authorities' silicon fiml 1 and the 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, and central silicon fiml 1 is the sensor measurement position with the beam diaphragm structure that silicon cantilever 2 forms;

Have the gap of 350-370 μ m so that central matter silicon fiml 1 is unsettled between described central silicon fiml 1 and the peripheral support silica-based 3, and fluid is passed 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 has adopted (100) crystal face silicon, is crossing distribution.

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

The present invention adopts the 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 flow perception and metering circuit, adopt simultaneously the 250um(100 crystal face) N-type twin polishing silicon wafer to manufacture, so it is little to have a volume, weight is little, fast response time and highly sensitive advantage.

Description of drawings

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 consists of.

Embodiment

Below in conjunction with accompanying drawing structure of the present invention and principle of work are described in detail.

Referring to Fig. 1 and 2, a kind of beam film four girder construction silicon microflow sensor chips, comprise peripheral support silica-based 3, support silica-based 3 the back side in the periphery and dispose glass substrate 4, 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 peripheral silica-based 3 the centre of supporting, link to each other by four silicon cantilevers 2 between central authorities' silicon fiml 1 and the 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, central authorities' silicon fiml 1 is the sensor measurement position with the beam diaphragm structure that silicon cantilever 2 forms, the flow signal input that sensor chip is sensed finally is converted into electric signal by the metering circuit that four pressure drag bars 5 form, and finishes induction and measurement to flow.

There is the gap of 350-370 μ m so that central silicon fiml 1 is unsettled between described central silicon fiml 1 and the peripheral support silica-based 3, and so that fluid can pass through, central authorities' silicon fiml 1 can be done the certain displacement of time spent generation at extraneous flow, thereby 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 makes stress concentrate effect obviously less than 1 width of central silicon fiml.

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 has adopted (100) crystal face silicon, is crossing distribution.

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

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

Referring to Fig. 3 and Fig. 4, four pressure drag bars 5 are respectively resistance R 1, R2, R3 and R4, and on four silicon cantilevers 2, resistance R 1 and resistance R 3 layouts in alignment, resistance R 2 are straight line with resistance R 4 arranges, four pressure drag bars 5 connect and compose Wheatstone bridge.

Principle of work of the present invention is:

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

The variable quantity of pressure drag bar 5 resistances among the present invention on the silicon cantilever 2 calculates by the correlation formula of piezoresistive effect, and piezoresistive effect refers to when semiconductor material is subject to effect of stress, since the variation of carrier mobility, the phenomenon that its resistivity is changed.When the pressure drag bar is in certain effect of stress lower time, the scale relation between its change in resistance and its suffered stress is as follows:

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

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

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

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

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

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

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

Claims (4)

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

There are the gap of 350-370m in described central silicon fiml (1) and peripheral the support between silica-based (3) so that central matter silicon fiml (1) is unsettled, and fluid is passed through smoothly, and 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 peripheral two axis supporting silica-based (3), and overlap with the axis of two silicon cantilevers (2) respectively.

2. a kind of beam film four girder construction silicon microflow sensor chips according to claim 1, it is characterized in that: described silicon cantilever (2) has adopted (100) crystal face silicon, is crossing distribution.

3. a kind of beam film four girder construction silicon microflow sensor chips according to claim 1 is characterized in that: described four pressure drag bars (5) along [110] and

The crystal orientation is arranged.

4. a kind of beam film four girder construction silicon microflow sensor chips according to claim 1, it is characterized in that: the present invention adopts the 250um(100 crystal face) N-type twin polishing silicon chip.

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