CN1257578A - Batch fabricated semiconductor thin-film pressure sensor and method of making same - Google Patents

Abstract

A pressure sensor having a flexible membrane which is moved by an external force, such as pressure from an air flow. The flexible membrane extends over a semiconductor frame having an opening, such that a portion of the flexible membrane extends over the semiconductor frame, and a portion of the flexible membrane extends over the opening. An inherent tensile stress is present in the membrane. One or more strain gage resistors are formed on the portion of the membrane which extends over the opening of the semiconductor frame. The membrane deforms in response to an externally applied pressure. As the membrane deforms, the strain gage resistors elongate, thereby increasing the resistances of these resistors. This change in resistance is measured and used to determine the magnitude of the external pressure. In one embodiment, a Wheaststone bridge circuit is used to translate the change in resistance of the strain gage resistors into a differential voltage.

Description

Fabricated semiconductor thin-film pressure sensor and the manufacture method thereof produced in batches

The present invention relates to carry out the pressure transducer of physical motion in response to externally applied forces.The present invention also relates to make the technology of this sensor.

Traditional silicon micromachined pressure sense die generally uses voltage dependent resistor (VDR) or capacity cell to measure the distortion of thin silicon films.Piezoresistive element is more commonly used than pressure-sensitive capacity cell, because piezoresistive element has lower cost, the user is comparatively familiar, is easy to accept.

Figure 1A is the vertical view of the little processingpiezoresistive pressure sensor 1 of traditionalsilicon.Pressure transducer 1 is to make on asilicon chip 2, and it has the area of a 2mm * 2mm and the thickness of about 500 μ m.In order to improve the sensitivity ofpressure transducer 1, thesubstrate 2 of manufacturing comprises a framework 2a, atorus membrane 2b and a circularplatform 2c.Film 2b is etched into the thickness with about 10 μ m, keeps the thickness of about 500 μ m with time-frame 2a and platform 2c.As a result, the distortion ofsubstrate 2 concentrates in thetorus membrane 2b, thereby improves the sensitivity ofpressure transducer 1.

Onsubstrate 2, be formed with fourwheatstone bridge circuits 3a, 3b, 3c and 3d.Each wheatstone bridge circuits comprises the conductive traces of a plurality ofcontact mats 4, a plurality ofpiezoresistive element 5 and many thesecontact mats 4 and this piezoresistive element 5.It is by forming totorus membrane 2b ion implanted impurity district thatpiezoresistive element 5 forms.The electrical response ofpiezoresistive element 5 changes in the mechanical stress that is applied to crystal substrates 2.More particularly, the resistance ofpiezoresistive element 5 is along with the compression offilm 2b and the variation of expanding.The position oftorus membrane 2b andpiezoresistive element 5 increases instrument factor (gauge factor) 25-50 doubly, makes when the design pressure difference scope is about 4 inchess of water(in H, andpressure transducer 1 forms the output voltage of about 2-3 millivolt/volt.

In the past,pressure transducer 1 generally was used for high-tension measurement in automobile.These application comprise as measuring manifold absolute pressure, fluid transmission pressure, cooling medium and power steering pressure and tire pressure.

The efficient ofpressure transducer 1 is by the combination decision of two physical influences, and this can be interpreted as mechanical amplifier and subsequent electric amplifier.Mechanical amplifier is thefilm 2b that pressure is converted to displacement.Electric amplifier is the combination ofpiezoresistive element 5 and wheatstone bridge circuits 3a-3d, and displacement conversion is become output voltage.

The inherent defect relevant withpressure transducer 1 has several.At first,platform 2c plays the vibrating mass effect, and its response shock and vibration (noise) causes too much dynamicdeformation amount.Platform 2c also can respond gravity and cause quiet deflection, thereby makes sensor extremely responsive to the installation site.As a result, the operation ofpressure transducer 1 influence ofsensor 1 installation site and environment that can be stressed.

In addition,piezoresistive element 5 plays thermistor, makes 1 pair of temperature variation of pressure transducer extremely responsive.As a result, the temperature-compensation circuit ofgeneral pressure transducer 1 necessary adapted complexity.Even general after temperature compensation, temperature effect is still about about the 1-2% of whole process.

Andtorus membrane 2b is generally very crisp, thereby makespressure transducer 1 be easy to damage in transportation, contact and assembling.In addition, thoughtorus membrane 2b has improved the sensitivity of the mechanical amplifier part ofpressure transducer 1, the shape oftorus membrane 2b has limited its linear elasticity scope.As a result, if the distortion offilm 2b surpasses the linear elasticity scope of silicon fiml, the performance ofpressure transducer 1 can be non-linear.

Have, because the self-stiffness ofsilicon chip 2,pressure transducer 1 is suitable for high-tension measurement (that is, measuring the pressure greater than 1 pound/square inch (psi)), and is unsuitable for low pressure (that is, mensuration is less than the pressure of 1 pound/square inch (psi)) again.

Figure 1B is the sectional view that is used for the traditional capacitancedifferential pressure pickup 20 of measuringpressure.Pressure transducer 20 is by being clipped inupper glass plates 30 with an etched silicon fiml 29 (being formed bysilicon fiml 28 etchings) and 27 of lower glass plateform.Pressure channel 25 and 26 passes upper andlower glass plate 30 and 27 respectively and makessilicon fiml 29 and be interlinked to the outside.Aluminium is splashed on the inside surface of lower glass plate to formfixing capacitor plate 23 and 24.Connector 21 and 22 extends to the outside surface oflower glass plate 30 and 27 respectively frompole plate 23 and 24 walls alongpressure channel 25 and 26.Silicon fiml 29 forms the movably center capacitor plate ofsensor 20, and its structural similarity is in the condenser type pot.The normal pressure that applies topressure channel 25 makessilicon fiml 29 tolower glass plate 27 distortion, thereby increases the electric capacity of 24 onfilm 29 and pole plate, reduces the electric capacity of 23 onfilm 29 and pole plate simultaneously.Direct and proportional this imbalance of pressure is determined by electronic circuit.

Pressure transducer 20 has following shortcoming.At first, thesilicon fiml 29 of thicker (just, at least about 5 micron thickness) may be subjected to excessive dynamic deformation in response to shock and vibration.And, doingfilm 29 thinlyyer for low pressure measurement when (that is, about 5 micron thickness), it is difficult making a film that is roughly the plane.Nonplanar film can cause the error of capacitance measurement.And when doingfilm 29 thinly for low pressure measurement, it is very crisp that film becomes, and makes pressure transducer 20 be easy to damage when transportation, contact and assembling.

Therefore wishing has low, the reliable pressure transducer of a cost, and it is more insensitive to temperature, dynamic impulsion and gravity.Wish that also this pressure transducer is firmer, and wide linear elasticity scope is arranged.And can be applicable to the low pressure occasion preferably.

Therefore, the invention provides a kind of pressure transducer of sensitivity, it comprises a flexible film, and as the nitride film of low-stress silicon, it is supported by the semiconductor frame.Flexible film extends on frame, and has an intrinsic tension in the film.The film strain gauge material is deposited on the flexible film as the nickel-chrome material, thereby forms one or more variable resistors on flexible film.

Because the dynamic pressure degradation external pressure that causes of airflow when being added on the film, film produces distortion, no longer is the plane.At this moment, variable resistor length increases, thereby resistance increases.An electronic circuit monitors this increase of resistance as wheatstone bridge circuits.One of sensor circuit generation and film are out of shape proportional output signal.Because in film, only there is tension (but draw and have the compressive stress opposite) with existing in the film of thicker and support bends, the output signal that forms by pressure transducer of the present invention, at film is to be identical when being out of shape up or down, makes that output signal and pressure reduction are proportional.

Because there is not detection mass body to be installed to flexible film, pressure transducer of the present invention is not hit, the influence in vibration and orientation.In addition, the resistance of strainmeter material is to be decided by geometrical factor purely, makes that pressure sensor temperature stability of the present invention is high.And flexible film produces moderate finite deformation (withsensor 1 ratio) for the given pressure reduction that applies.This provides sensitive and stable sensor, is suitable in low pressure applications.

Flexible film is by the high-strength material manufacturing that can resist big pressure reduction.Because film is under the tension, the displacement and the linear ratio of applied pressure of coming out from plane deformation.And because film is thin, its quality can be ignored, and makes owing to dealing with the gravity that causes improperly little of not damaging pressure transducer.

Pressure transducer of the present invention can be as matrix installation separately in a modular housing.In addition, pressure transducer can be installed in two silicon intermodes, plays overvoltage limiter, with the distortion of restriction film.

According to another embodiment, one first conductive layer is formed on the film, and one second conductive layer is formed on the overvoltage limiter.In this embodiment, first and second conductive layers form capacitance pressure transducer.

With reference to accompanying drawing, by following detailed description, the present invention may be better understood.

Figure 1A is the vertical view of the traditional little processing piezo-electric pressure sensor of silicon;

Figure 1B is the cut-open view of traditional electric capacity differential pressure pickup;

Fig. 2 is thin film sensor (transducer) pressure transducer vertical view according to an embodiment of the invention;

Fig. 3 is a pressure transducer backplan shown in Figure 2;

Fig. 4 is the cut-open view along Fig. 2 center line 4-4 gained pressure transducer;

Fig. 5 A-5G is a cut-open view, shows in the treatment step of selecting the pressure transducer shown in Fig. 2-4;

Fig. 6 A and 6B illustrate the distortion of the film of pressure transducer shown in Fig. 2-4;

Fig. 7 is a cut-open view, shows the pressure transducer shown in Figure 2 that has upper and lower excess pressure limiter;

Fig. 8 is a backplan of going up the overvoltage limiter structure shown in Figure 7;

Fig. 9 is a cut-open view, shows the capacitive pressure transducer of another embodiment of the present invention;

Figure 10 A is the cut-open view of pressure sensor assembly according to an embodiment of the invention;

Figure 10 B is the vertical view of the air flow tube of pressure sensor assembly shown in Figure 10 A;

Figure 11 is the cut-open view of a pressure transducer, and it can be used as the temperature sensor according to one embodiment of the invention;

Figure 12 is the synoptic diagram of a pressure transducer, and it can be used as vacuum transducer according to another embodiment of the present invention;

Figure 13,14 and 15 is cut-open views of pressure transducer, and they can be used as pitot tube (pitot tubes) according to another embodiment of the present invention;

Figure 16 is the cut-open view of a pressure transducer, and it is used as chemical substance analyzer according to another embodiment of the present invention after revising.

Fig. 2 is the vertical view ofpressure transducer 200 according to an embodiment of the invention.Fig. 3 is the backplan of pressure transducer 200.Fig. 4 is the cut-open view along thepressure transducer 200 of line 4-4 gained shown in Figure 2.Fig. 2-4 uses illustrated X-Y-Z coordinate system.

Pressure transducer 200 comprises:semiconductor frame 201;Flexible film 202; Conductive traces 211-214; Conductive pad 211a-214a; With strainmeter resistance 221-224.Semiconductor frame 201 is single-crystal semiconductor materials.In described example,frame 201 is to have＜100〉direction monocrystalline silicon.Yet in other example, frame also can be made by other semiconductor material.The size offrame 201 is along the about 0.6cm of X-axis, along the about 0.6cm of Y-axis, along the about 400 μ m of Z axle.One opening that is provided with in the centre, 203 complete break-through frames 201 extend.

Frame 201 supports a low stress, flexible film 202.In described example,film 202 is nitride films of high silicon content silicon, and it extends on the opening on the upper surface offrame 202 203.In described example, the nitride film thickness of silicon is about 2,000 dusts.In other embodiments,film 202 can as polyimide, be made by other material.The inherent tension offilm 202 is tended tofilm 202 is remained in the plane parallel with X-Y plane.Yetfilm 202 is along the deformable of Z axle.Therefore, be fixed and when Zaxial membrane 202 applied a power,film 202 distortion were moved along the Z axle at frame 201.Power about 250 little newton thatfilm 202 distortion are needed.When these power existed,film 202 was along the about 0.5 μ m of the amount of Z shaft distortion.

Traditional relatively piezoresistive pressure sensor 1 (Figure 1A),film 202 provide a mechanical enlargement factor that significantly improves.Becausefilm 202 is to have prestressedly, film plays one and hangs the effect of the tension cable in the bridge rather than play the cantilever beam action.Rigidity is not the function of membrane material Young modulus or cross section inertia on the disengaging plane of film 202 (out of plane), but the function of the intrinsic tension of the correct control of film 202.The intrinsic prestress process offilm 202 will illustrate in the manufacturing aboutpressure transducer 200 below.

Strainmeter resistance 221-224 is formed on the exposing surface of film 202.Strainmeter resistance is defined as the resistance that forms from the strainmeter material.The strainmeter material is defined as to have with the length of material and is directly proportional, with the conductive material of the long-pending resistance that is inversely proportional to of material section.In described example, strainmeter resistance is by nickel-chrome manufacturing (about 80% nickel, 20% chromium).Other strainmeter materials comprise chromium or titanium.The selection of strainmeter resistance 221-224 wantsconvenient film 202 along the Z axle when indeformable, and they have equal length and sectional area.As a result, whenfilm 202 was indeformable along the Z axle, strainmeter resistance 221-224 had identical resistance.In described example, whenfilm 202 was indeformable along the Z axle, each strainmeter resistance 221-224 had the thickness of about 5000 dusts and about 5000 ohm resistance (room temperature).Though in described example, strainmeter resistance 221-224 chemical analysis is identical, this is not of the presently claimed invention.In less preferred embodiments, also available being different from made used strainmeter material (comprising non-strainmeter material) themanufacturing resistance 223 and 224 of strainmeter resistance 221-224.In this embodiment,resistance 223 and 224 is designed to, whenfilm 202 is indeformable along the Z axle, has identical resistance with strainmeter resistance 221-222.

As shown in Figure 2, strainmeter resistance 221-222 forms the semicircle spiral.Strainmeter resistance 221-222 is formed entirely on the part of thefilm 202 that is not directly connected on the frame 201.That is, strainmeter resistance 221-222 is formed on the part of thefilm 202 on theopening 203 that is positioned at frame 201.(being shown in dotted line opening 203 among Fig. 2).As a result, whenfilm 202 when X-Y plane moves out, it is big that the length of strainmeter resistance 221-222 becomes, sectional area reduces.As described below, under these conditions, the resistance of these strainmeter resistance 221-222 increases.

As shown in Figure 2,strainmeter resistance 223 and 224 forms the straight line spiral.Strainmeter resistance 223-224 is formed entirely on the part of thefilm 202 that is directly connected on the frame 202.That is, strainmeter resistance 222-224 is formed directly on the frame 203.As a result, whenfilm 202 when X-Y plane moves out, strainmeter resistance 222-224 does not expand in any obvious mode.

Conductive traces 211-214 is by the low electrical resistant material manufacturing, as metal or alloy.In described example, stitching 211-214 is that thickness is about 2000 dusts by gold or billon manufacturing, and width is about 100 μ m.As a result, the resistance of the resistance ratio strainmeter resistance 221-224 of stitching 211-214 is much smaller.Stitching 211-214 couples strainmeter resistance 221-224, forms a wheatstone bridge circuits.Particularly,stitching 211 is couple to one first terminal ofresistance 223 one first terminal of resistance 221.Stitching 212 is couple to one second terminal ofresistance 223 one first terminal of resistance 222.Stitching 213 is couple to one second terminal of resistance 222 one first terminal of resistance 224.Stitching 214 is couple to one second terminal of resistance 221 one second terminal of resistance 224.Pad 211a-214a is respectively formed on the end of stitching 211-214, thereby forms the tie point of wheatstone bridge circuits.

Pressure transducer 200 is to make with following method according to an embodiment of the invention.Fig. 5 A-5G shows thepressure transducer 200 in the middle of concrete treatment step.At first, cleaning monocrystalline silicon substrate 201.Then, shown in Fig. 5 A, the nitride of deposition one deck silicon onsubstrate 201 outside surfaces.In described method, the thickness of thenitride layer 202 of silicon is about 2000 dusts, although other thickness also can.Shown in Fig. 5 B, then, deposition onephotoresist layer 501 on thenitride layer 202 of silicon.Photoresist layer 501 is patterned, to form an opening 502.In described method, this opening is square.

With reference to figure 5C, carry out plasma etching and remove the part that is exposed to the open air byopening 502 on thenitride layer 202 of silicon.After removing photoresist, on resulting structure, carry out potassium hydroxide etch.Shown in Fig. 5 C, potassium hydroxide etch forms opening 203, and it passessubstrate 201, thereby makessubstrate 201 form frame 201.Because potassium hydroxide is thenitride layer 202 of etching silicon not, thenitride layer 202 of silicon stays, and becomes the film of striding opening 203.Because described manufacture method, thisfilm 202 has intrinsic tension.

Shown in Fig. 5 D, thegold layer 215 that thickness is about 2000 dusts is evaporated (or sputter) on the whole lower surface of thenitride layer 202 of silicon.According to traditional treatment technology, composition and etching on thisgold layer 215 are to form the stitching 211-214 shown in Fig. 5 E.Thickness is about strainmeter material layer 216 (as the nickel-chrome) evaporation (or sputter) of 500 dusts on thenitride layer 202 whole lower surfaces of silicon.Then,, be composition and etching on this ply strain instrument material, form strainmeter resistance 221-224, and finish the manufacture process (Fig. 5 G) ofpressure transducer 200 according to traditional treatment technology.In other embodiment of the present invention, the etchant beyond the available hydrogen kali.

Though Fig. 5 A-5G shows the manufacturing ofsingle pressure sensor 200, should be understood that and on a silicon wafer, can make a plurality of pressure transducers (just produce) similar simultaneously to pressure transducer 200.The pressure transducer of these batch processes can cut into single pressure transducer according to the conventional semiconductor treatment technology.Therefore, the pressure transducer of these batch processes can be used as the integrated array of pressure transducer.

To introduce the principle of work ofpressure transducer 200 below.Under stable atmospheric condition (i.e. 1 atmospheric pressure, no environment air flow), or when in the film both sides equal pressure being arranged,pressure transducer 200 remains in the position shown in Fig. 3-4.That is,film 202 is basically parallel to X-Y plane, the distortion thatfilm 202 does not have along the Z axle.As a result, strainmeter resistance 221-224 has equal resistors.Apply fixing external voltage (perhaps by plate mat 212a-214a) by plate mat 211a and 213a.Because strainmeter resistance 221-224 has same resistance this moment, plate mat 212a-214a does not have voltage difference.

Yet, when atmospheric conditions make external pressure be added on the pressure transducer 200 (, pushing away or pulling force of plus or minus Z-direction),film 202 breaks away from the X-Y plane distortion, causes that strainmeter resistance 221-222 elongates.Fig. 6 A shows the distortion offilm 202 in Z axle positive dirction.Fig. 6 B shows the distortion offilm 202 in Z axle negative direction.When strainmeter resistance 221-222 elongated, the resistance of these strainmeter resistance 221-222 increased.Because the structure setting of strainmeter resistance 221-222 is that strainmeter resistance 221-222 deflection about equally with respect to the distortion symmetry of film 202.The result that the resistance of strainmeter resistance 221-222 increases makes to stride across plate mat 212a and 214a generation voltage difference (if applying fixing input voltage on plate mat 211a-213a).Stride across the voltage difference of plate mat 212a and 214a and the ratio that is deformed into of film 202.Because the distortion and the pressure offilm 202 are proportional, the voltage difference and the pressure that stride across plate mat 212a and 214a are proportional.

Compare with traditional piezoresistive pressure sensor,pressure transducer 200 demonstrates following advantage.At first,pressure transducer 200 is sensitive especially, and energy measurement is than 1 pound of/square inch much smaller pressure, and for example,pressure transducer 200 has 5 inchess of water(in H (0.02 pound/square inch) gamut to the FR range of sensitivity of 0.005 inches of water(in H.In addition, owing to use prestress membrane,pressure transducer 200 has improved mechanical enlargement factor.And becausefilm 202 has prestress,film 202 has the great range of linearity and an overvoltage protection.Becausefilm 202 has lower quality, so-called gravity (G-force) almost can be ignored, thereby pressure transducer 200 is not subjected to because the influence of the moving error that static error (deviation of sensing station) that gravity causes or noise and vibration cause.The airflow that these superior characteristic makepressure transducer 200 can be used in following utmost point low-pressure scope is measured: ventilate with heating (HVAC) damping control, conduit airflow and filter pressure drop is measured, chemistry ventilation cabinet, hospital is indoor and the decontamination chamber in the convection current of environmental pressure, medicine instrument, Industry Control/monitoring and electronic installation cool off lump mensuration.

Pressure transducer 200 can work independently as mentioned above, or is connected on other structural member, and when being in excessive pressure (being overvoltage condition), described other structural member plays the effect of restriction film range of movement.Fig. 7 is connected to the one firstovervoltage limiter structure 300 ofpressure transducer 200 and the cut-open view of the secondovervoltage limiter structure 400.

First overvoltage limiter 300 is connected on the surface ofpressure transducer 200, its support membrane 202.First overvoltage limiter 300 comprises that one has thesubstrate 301 of a plurality of supportingpads 303, and supportingpad 303 is formed on the periphery of substrate 301.In described example,substrate 301 is a monocrystalline silicon.As shown in the figure, on supportingpad 303, form electric insulation layer 302.In described example,insulation course 302 ismonox.Insulation course 302 prevents whenfirst overvoltage limiter 300 is couple topressure transducer 200, stitching 211-214 and strainmeter resistance 221-224 short circuit.Select the combination of supportingpad 303 andinsulation course 302 highly to make it consistent along the ultimate range of the hope of Z axle positive movement withfilm 202.

Fig. 8 is the backplan of first overvoltage limiter 300.Periphery to limiter 300 extends from the center along four passages in a deep channel district 304.Deep channel district 304 makes the upper surface offilm 202 communicate with external pressure.In addition, if provideenough spaces 303 of supporting pads, deep channel district 304 can eliminate, andfilm 202 upper surfaces are communicated with outside atmosphere by the space in 303 existence of supporting pad.

Second overvoltage limiter 400 is being connected on thepressure transducer 200 on the opposite surfaces on the surface of support membrane 202.Second overvoltage limiter 400 comprises that one has thesubstrate 401 of a plurality of through holes 402.In described example,substrate 401 is amonocrystalline silicon.Hole 402 is to form (that is etching,, machinery or ultrasonic drilling) with traditionalsemiconductor technology.Substrate 401 is passed inhole 402, thereby the lower surface that makesfilm 202 and atmospheric pressure or another air chamber bysubstrate 401 communicate.In this embodiment, select the height ofsubstrate 201 consistent along the hope ultimate range of Z axle negative sense operation with film 202.If wish a bigger distance, can be atsubstrate 401 upper surfaces week rim etching supporting pad (similar) to supportingpad 303.

First andsecond overvoltage limiters 300 and 400 are connected on thepressure transducer 200 by cementing agent.The patterned surface that is provided by supportingpad 303 is the surface of some out-of-flatness (promptly discontinuous), and its advantage is to improve combination.In the change scheme of above-mentioned example,first overvoltage limiter 300 can comprise the hole bysubstrate 301, makesfilm 202 upper surfaces and is interlinked to the outside.Similarly,second overvoltage limiter 400 can comprise that passage (similar in appearance to passage 304) in thesubstrate 401 makesfilm 202 lower surfaces and ventilates outward.In another program, can usefirst overvoltage limiter 300, and not have second overvoltage limiter 400.Similarly, can usesecond overvoltage limiter 400, and not havefirst overvoltage limiter 300.

In another embodiment of the present invention, revise thepressure transducer 200 andfirst overvoltage limiter 300, produce a capacitance pressure transducer.Fig. 9 is the cut-open view according to thecapacitive pressure transducer 500 of this another embodiment of the present invention.Capacitive pressure transducer 500 comprises thepressure transducer 200A and the first overvoltage limiter300A.Pressure transducer 200A is similar withfirst overvoltage limiter 300 toaforesaid pressure transducer 200 with first overvoltage restriction limiter 300A.Therefore, among Fig. 7 and 9 similar part with the similarity number representation.

Pressure transducer 200A forms by finishing the treatment step that is introduced with regard to Fig. 5 A-5D.Therefore,pressure transducer 200A comprisesframe 201,film 202 and gold layer 215.Should point out that in this embodiment, composition not on thegold layer 215 does not form strainmeter layer 216.By depositing conductinglayer 305 in the passage area 304 of overvoltage limiter 300 (Fig. 8) (for example gold), form overvoltage limiter 300A.Conductive layer 215 and 305 is electrically connected, and the electric capacity of this two interlayer is measured by the traditional capacitance metering circuit.Whenfilm 202 whenovervoltage limiter 300A is out of shape, the electric capacity of measurement can increase.On the contrary, whenovervoltage limiter 300A was left infilm 202 distortion, the electric capacity of measurement can reduce.Can draw the numerical value of exerting pressure from the electric capacity of measuring with conventional art.

Use

To introduce the various application ofpressure transducer 200 below.The order of application described below is in order to illustrate, rather than as limitation of the present invention.To one skilled in the art, it should be understood that pressure transducer of the present invention can be applicable to a lot of other occasions.

The airflow analyzer

Pressure transducer 200 can be used for various occasions.Shown in Figure 10 A,pressure transducer 200 assemblings form pressure sensor assembly 900.Pressure sensor assembly 900 comprises a patrix 901 and a counterdie 902, and the both can be by the plastics manufacturing.Patrix 901 is fixed on the counterdie 902, forms the air tightening seal at twointermodes.Pressure transducer 200 is fixed on the counterdie, thereby forms the air tightening seal.Two cavitys 903 and 904 pass counterdie 902.Pressure transducer 200 is located on the cavity 904, and the lower surface ofmould 202 is exposed in the cavity 904.Cavity 903 passes counterdie 902 on the position outside the periphery of pressure transducer 200.As a result,film 202 upper surfaces reveal in the cavity 903.

Respectively air hose 910 and 911 is installed in cavity 903 and 904.Air hose 910 and 911 is topmost opening, the hollow tube of sealing bottom.Opening 930 and 931 lays respectively on the surface of pipe 910 and 911.Filtrator 920 and 921 is respectively on air hose 910 and 911 the tops.Filtrator 920 and 921 prevents that particle from entering the operating characteristic that changesfilm 202 in the shell 900.Respectively the connecting plate mat 211A-214A and can be connected on the connector latch (as connector latch 905) ofpressure transducer 200 by connecting line (as tack line 950).

The operation of resulting structures is as follows.Pressure sensor assembly 900 is installed in one and estimates to have on the position of airflow.Aim at pressure sensor assembly, make the airflow direction of opening 930, the airflow direction that opening 931 is estimated dorsad in the face of estimating.Figure 10 B is the vertical view of air flow tube 910 and 911.The airflow direction that arrow 1010 expressions are estimated.When such airflow exists, produce normal pressure P1 in the opening 930, produce negative pressure P2 in the opening 931.Opening 931 must be positioned at the airflow direction of estimating to be had on the position of 90 phase differential of spending at least, to produce negative pressure (vacuum) P2.When the airflow of estimating existed, the pressure reduction between P1 and P2 can be released X-Y plane with film 202.On the contrary, when the airflow of estimating did not exist, the pressure of P1 and P2 (approximately equating) was retained in indeformable state with film 202.By forming malleation P1 in a side offilm 202, forming negative pressure P2 at the opposite side offilm 202, the bigger power of generation activates pressure transducer.In another embodiment, air flow tube 910 and 911 can be replaced by the single air flow tube with two internal channels, and two internal channels all have a hole to be attached thereto.

In addition, replace the single hole in each air hose 910 and 911, each air hose 910 and 911 can comprise two or more holes, and each hole is positioned at respect on the different slightly angle of airflow, but all connects identical cavity (as 903 or 904).In an example, one about 5 angle of spending is arranged between two holes.Two holes are set allows air hose 910 and 911 form a low-angle accurately with respect to airflow direction.But, have each additional holes that appends to each air hose, to measure pressure and reduce, sensitivity reduces slightly.In another embodiment, the open seam of hole 930 and 931 available horizontal replaces.This open seam has alleviated the directed requirement of air hose with respect to airflow direction.

Pressure sensor assembly 900 can be installed in the computer system near the fan, or near the electronic package that will protect.Thereby makepressure transducer 200 accept the airflow that fan produces.When airflow during,film 202 distortion, thereby stride across plate mat 212a and 2143a produces voltage difference greater than a predetermined threshold.Then, the existence of voltage difference is transformed, and has enough airflows to indicate in system.The threshold value ofpressure transducer 200 can be determined with respect to the radial and axial position of fan by regulatingpressure transducer 200, or determine by the sensitivity that changes film 202.Becausepressure transducer 200 is directly measured the inefficacy or the bad operation of fan, can be than with electronic package in the earlier anti-locking system of traditional temperature measuring apparatus overheated.

The present invention of root a tree name, a plurality of pressure sensor assemblies identical with pressure sensor assembly 900 can be arranged in the total system that will protect.Such setting can determine the regional area of bad performance fan.

Except making alarm sensor, such device can be used as feedback transducer, controls the given system or the rotation speed of the fan of environment temperature, can control fan, makes it to be rotated under desirable air velocity.In addition, can control the number that to operate fan, to obtain the airflow of hope.Such adaptation (or intelligence) fan can be used on fan noise and is a problem, or system reliability is crucial position.

Temperature sensor

As shown in figure 11, according to another embodiment of the present invention, can form atemperature sensor 1100 by working pressure sensor 200.Temperature sensor 1100 comprises:pressure transducer 200; Lower casing spare 1101; Lastouter casing member 1102; Withplug 1103.Cavity 1104 passes lower casing spare1101.Pressure transducer 200 is fixed on theouter casing member 1101 by the air tightening seal, allowsfilm 202 lower surfaces (or upper surface) be exposed by cavity 1104.As shown in the figure, lastouter casing member 1102 is fixed on the lower casing spare 1101.Lastouter casing member 1102 comprises afiltrator 1105, and it makesfilm 202 upper surfaces (or lower surface) ventilation.When the control room temperature, 1103 sealings (airtight) ofcavity 1104 usefulness plug.As a result,cavity 1104 becomes an enclosed cavity that accommodates fixed-amount-of-air.When air heat (or cooling), it expands (or contraction), thereby makes the conducting film distortion.By the sensitivity of the sealed temperature andpressure sensor 200 ofcontrol temperature sensor 1100, can control the operating characteristic oftemperature sensor 1100.

The vacuum analyzer

In Another Application, can the workingpressure sensor 200 vacuum of measuring in the Room (or pressure), or measure airflow by the vacuum of measuring in the passage, as Room in an air-conditioning system, in a stove or the semiconductor processing equipment or the vacuum (or pressure) in the airflow.Figure 12 is the synoptic diagram of thevacuum pressure sensor 1200 of another embodiment of the present invention.Vacuum pressure sensor 1200 comprisespressure transducer 200, and it is fixed on the lower casing spare 1202.Opening 1203 passes shell 1202 and extends, thereby exposesfilm 202 lower surfaces (or upper surface).Last shell withfiltrator 1205 is fixed on the lower casing spare 1202.Lower casing spare 1202 and lastouter casing member 1204 are installed in thebig shell 1210, its tapped air stream pipe 1211 (as Venturi tubes).Do not having airflow by managing at 1211 o'clock, film is in indeformable state.But when introducing airflow F in thepipe 1211,film 202 is by the negative pressure P distortion that produces inshell 1210.

Pitot tube

In Another Application,pressure transducer 200 can be used in the micro-machined pitot tube of silicon (pitot tube).Figure 13 is the cut-open view of another embodiment of the present invention pitot tube 1300.In this embodiment, thesubstrate 201 ofpressure transducer 200 is extended, and forms agroove 1301 onsubstrate 201 upper surfaces that extend.Theupper strata 1311 that is made of structured materials such as monocrystalline silicon is fixed onsubstrate 201upper surfaces.Opening 1312 passes upper strata 1311.Opening 1312 andgroove 1301make film 202 upper surfaces communicate with outside atmosphere.

As shown in the figure, followingstructural sheet 1320 is fixed on the lower surface of pressure transducer 200.Followingstructural sheet 1320 comprises supportingpad 1321, and they produce:cavity 1322;Groove 1323 onlayer 1320 lower surface; With opening 1324, it extends in 1323 ofcavity 1322 andgrooves.Groove 1323 reaches downpoint 1325 places of the neighboring of structural sheet 1320.Lower caldding layer 1330 is fixed to down on the lower surface of structural sheet 1320.As a result, the lower surface offilm 202 communicates with outside atmosphere bycavity 1322,groove 1323 andopening 1324.

This structure can be used for measuring air velocity, as in a traditional pitot tube.Suppose that the airflow F that enters has speed V₁And pressure P₁, on any other aspect in flowing following relation is arranged so

P₂+1/2ρV₂²＝P₁+1/2ρV¹²

Wherein, ρ is an atmospheric density.Because opening 1325 directed towards air stream directions, andgroove 1323 extends tocavity 1322 always accordingly, herein, flow velocity V₂Be zero, the pressure onfilm 202 basal surfaces should be

P₂＝P₁+1/2ρV₁²

On the other hand, opening 1312 directed in orthogonal are in the direction of air-flow, so be P by the pressure ofgroove 1301 onfilm 202 top surfaces₁, the pressure reduction onfilm 202 is so

ΔP＝P₂-P₁＝1/2ρV₁²

This pressure reduction makesfilm 202 produce distortion.Then, this distortion causes the voltage difference that can be used for measuring airflow F again.

Utilize the structure ofpressure transducer 200 also can constitute the pitot tube of other structure.For example, Figure 14 shows the pitot tube 1400 of a three-decker, and it comprises threestructural members 1401,1411 and 1421 that are coupled on the pressure transducer 200.Structural member 1401 comprises: supporting pad 1402, opening 1403, passage 1404 and opening 1405.As shown in the figure, the upper surface of structural member 1401 (that is the surface that, comprises supporting pad 1402) is attached on the pressure transducer 200.Structural member 1411 is fixed to the lower surface of structural member 1401.

As shown in the figure, thestructural member 1421 that is fixed topressure transducer 200 comprises twoopenings 1422 and 1423.Opening 1422 has one 90 degree bendings, and it makesfilm 202 upper surfaceslogical outward.Opening 1423 is to head straight for mouth, and is continuous with theopening 1406 that forms in pressure transducer 200.Opening 1406 is inopening 1423 and 1405 extensions, thereby makesfilm 202 lower surfaces logical outward.Pitot tube structure 1400 is thought the 1300 described same way as work of pitot tube structure.

Similarly, Figure 15 shows a kind of two-layer pitot tube structure 1500.To skin intubular construction 1400 and 1500 similar element with the similarity number representation.Pitot tube structure 1500 usefulness single-node members 1501 replace the structural member 1401 and 1411 of pitot tube structure 1400.Structural member 1501 comprises supportingpad 1502 andpassage 1503, andpassage 1503 makes and communicates withopening 1423 and 1406 below the film 202.Passage 1503 forms with above-mentioned passage 304 (Fig. 8) same way as.Pitot tube structure 1500 is identical with the working method ofpitot tube structure 1300 and 1400.In another embodiment, the pitot tube structure can be made with another kind of material (as plastics), and adheres on the switch (by the silicon manufacturing).

The chemical substance analyzer

Pressure transducer shown in Figure 16 can be used as gas or chemical substance (as carbon monoxide) analyzer 1600.In this embodiment of the present invention,chemical absorbing material 1601 is deposited on thefilm 202 in the opening 203.Material 1601 is absorbed in the chemical substance in the ambient atmosphere.When absorbing,material 1601 expands, thereby the power that applies makesfilm 202 distortion.The voltage difference that is produced can be used for differentiating the harmful chemical that whether had volume in ambient atmosphere.

Though oneself has illustrated the present invention according to several embodiment, still, to those skilled in the art, it must be understood that the present invention is not restricted to the foregoing description, but has multiple modification.For example, even connect strainmeter resistance formation Wheatstone bridge the present invention has been described, but those skilled in the art can constitute other class and measure circuit by form one or more strainmeter resistance on the film of pressure transducer.In addition, though the pressure transducer of being introduced 200 has concrete size, these sizes are illustrative, are not restrictive.Other size also can be utilized, and all belongs to category of the present invention.The present invention is limited by following claim.

Claims (19)

1. pressure transducer, it comprises:

The semiconductor frame has opening:

One flexible film is extending on the semiconductor frame He on the semiconductor frame opening;

One first strainmeter resistance is formed on the part of the film that extends on the semiconductor frame opening.

2. pressure transducer according to claim 1, wherein, the semiconductor frame comprises monocrystalline silicon.

3. pressure transducer according to claim 1, wherein, film comprises the nitride of silicon.

4. pressure transducer according to claim 1, wherein, the first strainmeter resistance comprises nickel-chromium alloy.

5. pressure transducer according to claim 1 also comprises one second strainmeter resistance, is formed on the part of the film that extends on the semiconductor frame opening.

6. pressure transducer according to claim 5, wherein, the first strainmeter resistance and the second strainmeter resistance are symmetrical.

7. pressure transducer according to claim 5, wherein, the first strainmeter resistance and the second strainmeter resistance respectively have a spirally.

8. pressure transducer according to claim 5, wherein, the first strainmeter resistance has identical resistance value with the second strainmeter resistance.

9. pressure transducer according to claim 5 also comprises:

One the 3rd resistance is formed on the part of the film that extends on the semiconductor frame;

One the 4th resistance is formed on the part of the film that extends on the semiconductor frame;

A plurality of conductive traces are formed on the film, and wherein this stitching is connected to form wheatstone bridge circuits with the first strainmeter resistance, the second strainmeter resistance, the 3rd resistance and the 4th resistance.

10. pressure transducer according to claim 9, wherein, the 3rd resistance and the 4th resistance are strainmeter resistance.

11. pressure transducer according to claim 1 also comprises first limiter, is couple to the semiconductor frame, wherein first limiter extends on the film, and the restriction film is along the distortion of first direction.

12. pressure transducer according to claim 11 also comprises one second limiter, is couple to the semiconductor frame, wherein, second limiter extends on film, and the restriction film is along the distortion of second direction, and second direction is opposite with first direction.

13. the method for a pressure sensor may further comprise the steps:

Have one and to form a flexible film on the semiconductor frame of an opening;

On the part of the film that extends on the opening, form one first strainmeter resistance;

Make film be subjected to the effect of the pressure that will measure, thereby pressure make film and the distortion of strainmeter resistance;

Resistance measurement pressure with the first strainmeter resistance.

14. a method of making pressure transducer comprises the steps:

On the outside surface of semiconductor chip, form a rete;

The etching semiconductor substrate forms a frame, and described frame has an opening, and rete exposes on opening;

The one or more strainmeter resistance of system on rete.

15. a capacitance pressure transducer, comprises:

The semiconductor frame has an opening:

One flexible film is extending on the semiconductor frame He on the semiconductor frame opening;

One first conductive layer is formed on the flexible film;

One substrate has the district that is positioned at the center;

A plurality of outstanding supporting pads are provided with around the district that is positioned at the center;

One second conductive layer is formed in the district at center of substrate, and wherein supporting pad is couple on the semiconductor frame, and first conductive layer is supported must be parallel with second conductive layer.

16. pressure transducer according to claim 15, wherein, film is the nitride of silicon.

17. pressure transducer according to claim 16 also comprises one or more holes of passing substrate, makes film pass through the substrate exhaust.

18. pressure transducer according to claim 16 also comprises the one or more passages that are positioned on the substrate surface of film, thereby makes film by described one or more passage exhausts.

19. a method of making pressure transducer comprises the steps:

On one first substrate outside surface, form a rete;

Etching first substrate forms frame, and frame has opening, and rete exposes on opening;

On rete, form one first conductive layer;

Form a plurality of outstanding supporting pads around the second substrate center position;

Form second conductive layer in the second substrate center position;

Supporting pad is couple on the frame, and wherein, first conductive layer is supported must be parallel with second conductive layer.

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