CN1240995C - Microcantilever sensor and its making method - Google Patents

Abstract

The present invention relates to a microcantilever sensor and a making method thereof. The sensor comprises a chip. The sensor is characterized in that the chip is provided with at least one set of sensing units, wherein each sensing unit is composed of four force-sensitive resistors which form a wheatstone bridge and are completely the same and two cantilevers; two of the resistors are positioned on a substrate of the chip, and other two resistors are respectively positioned on the two cantilevers; one of the cantilevers is used as a measurement cantilever, and the other cantilever is used as a reference cantilever; the surface of the measurement cantilever has a sensitive layer. In the present invention, the cantilevers can be designed and prepared in a microflute in which a liquid can flow by a front etching technology and a silicon-glass bonding technology in order that the sensor can directly detect liquid biomolecules; the present invention performs important functions on the size decrease of devices, the sensitivity improvement of devices and the multifunction realization of the sensor no matter that the present invention is used for a gas sensor or a biological sensor; the present invention has a wide application prospect in the fields of environmental monitoring, clinical diagnosis and treatment, new medicine development, food safety, industry processing control, military, etc.

Description

Micro-cantilever beam sensor and preparation method thereof

Technical field

The present invention relates to a kind of sensor and preparation method thereof, particularly about the rectangular micro-cantilever beam sensor and preparation method thereof that is applied in biology, the chemical sensitisation of a kind of semi-girder.

Background technology

In 20 years of past, one of obvious improvement of microelectric technique is the development of new measuring technology.Scanning probe microscopy is one of well-known detection technique, and wherein scanning tunnel microscope and scanning force microscopy are the most representative two kinds of highly sensitive detecting instruments.The principle of work of scanning force microscopy be with probe stationary one to the highstrung micro-cantilever of faint power on, and make it and the testing sample surface atom between have the interaction of power, the power that acts between probe and the sample makes semi-girder generation deformation, and go on record, because micro-cantilever is very responsive to the variation of faint power, therefore can high-resolution imaging material surface pattern, the research surface nature.

The slight curves of semi-girder is come record by optics or electrical method usually.Optical detecting method can obtain little vertical resolution to 0.01 , though it has higher sensitivity, the huge optical measuring system and the close adjustment of laser have limited it and have used widely: as under ultrahigh vacuum, low temperature, the liquid condition and in the measurement of array semi-girder.The method of breaking away from this problem is integrated capacitance, piezoelectricity, the force sensing element electrical detection method in semi-girder, because the electrical detection method is easier to operation than optical means, is easy to turn to practicability.In the electrical detection method, pressure resistance type reading method on the throne is easier to realize than other detection technique.

In recent years, highly sensitive micro-cantilever technology is applied to the research focus that biology, chemical sensor become sensor field.This class sensor can be surveyed the existence of micro-biochemical molecular under gaseous state or liquid condition, as airborne organic gas, harmful gas, aromatic, and the DNA of liquid, protein etc.Although the research work of semi-girder biochemical sensor has obtained some achievements, also have with a certain distance from widespread use, particularly in liquid Study on Biosensor field.Problems such as simultaneously, it is complicated also to exist manufacture craft on the manufacture craft of beam type microsensor, and yield rate is lower.

Summary of the invention

The objective of the invention is to provide on the basis of existing technology a kind of measurement sensitivity higher, manufacture craft is simpler to be applied to micro-cantilever beam sensor in biology, the chemical sensitisation and preparation method thereof.

For achieving the above object; the present invention takes following technical scheme: a kind of micro-cantilever beam sensor; it comprises a chip; described chip is provided with at least one group of sensing unit; described sensing unit is made up of four identical force sensing resistances and two semi-girders of forming Wheatstone bridge; wherein two described force sensing resistances are positioned on the substrate of described chip; two other lays respectively on described two semi-girders; one of them described semi-girder is as measuring semi-girder; another is as the reference semi-girder; it is characterized in that: described chip is provided with a microflute; described semi-girder is arranged in the described microflute; the material of described force sensing resistance adopts monocrystalline silicon or polysilicon; be doped with the boron ion at described monocrystalline silicon or polysilicon front; on described force sensing resistance; lower surface is provided with silicon nitride or monox protective seam, forms described semi-girder jointly, and described measurement semi-girder surface is provided with sensitive layer.

Described sensitive layer is the high molecule sensitivity material.

Described sensitive layer is a bioactive molecule.

Described semi-girder is long 50～500 μ m, wide 10～100 μ m, thick 100～5000nm rectangle.

Described force sensing resistance is of a size of long 20～200 μ m, wide 5～50 μ m.

A kind of method for making of micro-cantilever beam sensor is characterized in that it may further comprise the steps:

1, adopt soi wafer, and the attenuate device layer is as chip substrate with oxide layer, single-crystal silicon device layer; Perhaps adopt single-sided polishing p type silicon chip, carry out after routine cleans, at silicon chip surface plasma enhanced CVD silicon nitride, then at silicon nitride surface low pressure chemical vapor deposition polysilicon as chip substrate;

2, monocrystalline silicon or the injection of polysilicon front boron ion are mixed;

3, with mask plate the chip through step 2 is carried out the photoetching first time,, form force sensing resistance through etching;

4, the chip surface through step 3 is passed through the plasma enhanced CVD silicon nitride, in AN;

5, with mask plate the chip through step 4 is carried out the photoetching second time,, form force sensing resistance contact hole and semi-girder through etching;

6, the chip surface through step 5 is passed through electron beam, sputter chromium/golden thermometal film;

7, with mask plate the chip through step 6 is carried out photoetching for the third time,, form the metal wire that connects each force sensing resistance through corrosion;

8, on entire chip, carry out the scribing of single-sensor;

9, with the chip of potassium hydroxide corrosion, discharge semi-girder through step 8;

10, metal wire in the force sensing resistance contact hole on the chip and chip substrate are carried out alloy treatment;

11, be single-sensor with the entire chip sliver;

12, a semi-girder surface in per two semi-girders is provided with sensitive layer.

Wherein step 5 forms the microflute on the chip when forming force sensing resistance contact hole and semi-girder.

Step 1 wherein, the oxidated layer thickness of soi wafer is 200～800nm, device layer thickness is 100～500nm.

Step 1 wherein, when silicon chip surface carried out the plasma enhanced CVD silicon nitride, the thickness of silicon nitride was 100～1000nm.

Step 1 wherein, when the low pressure chemical vapor deposition polysilicon, the thickness of polysilicon is 100～500nm.

Step 2 is wherein injected when mixing monocrystalline silicon or polysilicon front boron ion, and the concentration of injecting the boron ion is 5 * 10 ¹³Cm ^-2～5 * 10 ¹⁵Cm ^-2, inject energy 30keV～80keV.

Step 4 wherein, during the plasma enhanced CVD silicon nitride, silicon nitride thickness is 100～1000nm, 900～1100 ℃ of annealing 20～30 minutes in nitrogen then.

The present invention is owing to take above technical scheme, it has the following advantages: 1, the present invention is owing to be separately positioned on two resistance in the Wheatstone bridge on two semi-girders, one as measuring resistance, another is as reference resistance, rather than reference resistance is arranged on the substrate of chip, when therefore measuring, when external environmental noise makes semi-girder deformation, this additional signals can be filtered by the reference semi-girder, makes measurement result more accurate.2, semi-girder of the present invention is the array arrangement, and with two adjacent semi-girders is one group, therefore can be by on semi-girder, being coated with different high molecule sensitivity layer, bioactive molecule, make each can finish a kind of measurement function by sensitive layer, and then measure when can realize different material various characteristics index to semi-girder.3, the present invention is in the manufacture craft of semi-girder, microflute on contact hole, semi-girder and the chip that metal lead wire is connected with force sensing resistance adopts same mask plate definition, that is only adopted three mask plates in the present invention, compared to existing technology, the present invention has simplified technological process effectively.4, the present invention is owing to select for use gold as metal lead wire, therefore can resist long KOH corrosion, simultaneously owing to adopt KOH corroding method after the first scribing, avoided having discharged behind the semi-girder semi-girder damage that scribing again causes effectively, and then improved yield rate effectively.5, the present invention can design semi-girder, prepare in the flowable microflute of liquid by front etch technology and silicon～glass (polymkeric substance) bonding techniques, can be directly used in the detection of liquid biomolecule like this.

Description of drawings

Fig. 1 is a structural representation of the present invention

Fig. 2 is a Wheatstone bridge synoptic diagram of the present invention

Fig. 3 is the enlarged diagram that micro-cantilever of the present invention is arranged on chip one side

Fig. 4 a～4j is a process flow diagram of the present invention

Embodiment

As Fig. 1, Fig. 2, shown in Figure 3, the invention belongs to the pressure resistance type microsensor, it comprises a chip 1, and it is provided with a microflute 2, be provided with four groups of sensing units 3 in microflute 2 symmetria bilateralis, every group of sensing unit 3 comprises two semi-girders 4 and one group of Hui Sitong (Wheatstone) electric bridge 5.Every group of Wheatstone bridge 5 is made up of four identical force sensing resistance R1, R2, R3, R4, and wherein two resistance R 1, R4 are connected on two semi-girders 4, and semi-girder 4 ' is measured in a conduct, and another is as reference semi-girder 4 ".Again two other resistance R 2, R3 are connected on the substrate of chip 1.With reference resistance R4 design at reference semi-girder 4 " on, rather than to be arranged on chip 1 substrate be to consider when external environmental noise and hot mechanical shock noise make semi-girder 4 deformation, this additional signals can be by with reference to semi-girder 4 " filter.Different needs on semi-girder 4 ' surface according to measurement of species can be coated with high molecule sensitivity material, bioactive molecule or metal etc. as the sensitive layer (not shown) on the surface of measuring semi-girder 4 '.

Such as: at bioactive molecules such as semi-girder 4 ' the surperficial fixed dna, protein, realize micro-Recognition of Biomolecular such as DNA, protein by the specificity association reaction between reaction of the hydridization between dna molecular or protein.The sensor of measuring DNA is at the surperficial fixedly single strand dna of known array (being also referred to as the ssDNA probe) of semi-girder, detected biomolecule is the ssDNA molecule (being also referred to as target dna) of a complementation, both results of hydridization reaction form double-stranded DNA, power in the course of reaction makes the semi-girder bending, shows certain variation of output signals.The sensor of measuring protein is fixed on antibody the semi-girder surface usually, based on two kinds of intermolecular complementary structures and compatibility, form antigen antibody complex, it is crooked that antigen-antibody produces semi-girder in conjunction with (electric charge gravitation, Fan Denghua gravitation, hydrogen bonded power, hydrophobic adhesion).The slight curves of semi-girder 4 changes the resistance of force sensing resistance R1, biomolecule and the intermolecular reaction of sensitive layer that the differential voltage signal record is detected.

In the foregoing description, the design size of semi-girder 4 can be: long 50～500 μ m, wide 10～100 μ m, thick 100～5000nm.Four identical force sensing resistance sizes forming symmetrical Wheatstone bridge 5 can be: long 20～200 μ m, wide 5～50 μ m.After semi-girder is stressed, the moment M and the moment of inertia I of semi-girder depended in the distribution of stress, can prove that maximum stress usually occurs in the semi-girder surface, the meridional stress σ on release cantilever arm this moment and the power F of semi-girder end points and the pass of vertical displacement delta z are theoretically:

${\mathrm{\&sigma;}}_l=\frac{6(l-L/2)}{{\mathrm{wt}}^2}F=\frac{3E(l-L/2)}{{2\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="C0310949200111.png"\; state="\{\{state\}\}">l</figure-callout>}}^3}\mathrm{\&Delta;}\text{z----}\left(1\right)$

Wherein l, w and t are the length of semi-girder,, width and thickness L be the length of force sensing resistance, t is the thickness of semi-girder, E is a Young modulus, Δ z is the perpendicular displacement of semi-girder end points.

If only consider meridional stress, relative change rate's Δ R/R of force sensing resistance can be provided by following formula:

$\frac{\mathrm{\&Delta;R}}{R}=\mathrm{\&sigma;\&pi;}---\left(2\right)$

Wherein π is vertical piezoresistance coefficient.Measure semi-girder because the effect of power when producing deformation, the change in resistance of semi-girder force sensing resistance is Δ R, and when bias voltage V acted on the Wheatstone electric bridge, the output signal of Wheatstone electric bridge was:

$V_o=\frac{V_{\mathrm{<figure-callout\; id="4"\; label="bias"\; filenames="C0310949200111.png,C0310949200121.png"\; state="\{\{state\}\}">bias</figure-callout>}}}{4}\frac{\mathrm{\&Delta;R}}{R}---\left(3\right)$

The measurement sensitivity definition of semi-girder is the relative variation of resistance and the ratio of semi-girder end points side-play amount.Stress result substitution formula (2) with (1) formula is calculated then can obtain the variation relation of the relative variation of resistance with power, and according to the definition of Hooke's law (Hook ' s) and elasticity coefficient, the measurement sensitivity of semi-girder can be expressed as:

$\frac{\mathrm{\&Delta;R}}{R}\mathrm{\&Delta;}{z}^{-1}=\frac{3{\mathrm{\&pi;}}_l\mathrm{Et}(l-L/2)}{2{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="C0310949200111.png"\; state="\{\{state\}\}">l</figure-callout>}}^3}=\frac{3\mathrm{Kt}(l-L/2)}{2l^3}---\left(4\right)$

K=E π in the formula _lBe ga(u)ge factor.

The signal noise ratio that the minimum detectable displacement (MDD) of the quick semi-girder of power is defined as semi-girder is the perpendicular displacement amount of 1: 1 condition lower cantalever beam, and it not only depends on the detection sensitivity of semi-girder, simultaneously the restriction of stressed quick resistance noise.Make Wheatston bridge output voltage signal V _oEqual overall noise, the MDD of semi-girder can be expressed as:

$\mathrm{MDD}=\frac{4}{V_{\mathrm{bias}}}{[\frac{a{V_{\mathrm{bias}}}^2}{N}\ln \frac{f_{\max }}{f_{\min }}+4K_B\mathrm{TR}(f_{\max }-f_{\min })]}^{1/2}/K\frac{3(l-\frac{1}{2}L)t}{2l^3}---\left(5\right)$

In the following formula, first correspondence in the brace puted forth effort the 1/f noise of quick resistance, and second correspondence puted forth effort the Johnson noise of quick resistance.

Can be found out that by formula 5 noise and sensitivity are equilibrium process, the actual design size wants the combined process condition to select.The force sensing resistance size at first influences the noise of force sensing resistance, and the big more noise of size is more little.The semi-girder size influences the sensitivity and the noise of semi-girder equally,

The present invention has only adopted three mask plates by optimal design has been carried out in technological process in the making of micro-cantilever, compare other method for making, has carried out bigger simplification in technological process.Be making of the present invention below

Embodiment:

1, make chip substrate, it can adopt monocrystalline silicon or polysilicon dual mode,

When (1) making the polysilicon semi-girder, can be single-sided polishing p type silicon chip 10, silicon chip 10 is carried out routine cleaning after, carry out plasma enhanced CVD (PECVD) silicon nitride (Si on silicon chip 10 surfaces ₃N ₄) 11 (shown in Fig. 4 a), being used to seal the bottom of force sensing resistance, thickness is 150nm; Low pressure chemical vapor deposition (LPCVD) polysilicon 12 (shown in Fig. 4 b) then, thickness is 200nm, forms polysilicon force sensing resistance layer.

When (2) making the single-crystal silicon cantilever beam, can be SOI (silicon structure on the insulator) silicon chip, its surface is handled, the attenuate device layer, oxidated layer thickness is: 400nm, device layer thickness is: 200nm, device layer are monocrystalline silicon force sensing resistance layer.

2, the monocrystalline silicon that will handle through step 1 or polysilicon silicon chip inject 13 (shown in Fig. 4 c) that mix as chip substrate to its front boron ion, inject the concentration 5 * 10 of boron ion ¹³Or 5 * 10 ¹⁵Cm ^-2, inject energy 30keV.

3, adopt mask plate to carry out the figure conversion of force sensing resistance, monocrystalline silicon or polysilicon after mixing are carried out SF ₆(sulfur hexafluoride) reactive ion etching (RIE) forms force sensing resistance R (shown in Fig. 4 d).

4, be the quick resistance R of complete sealing force, plasma enhanced CVD silicon nitride 11 (shown in Fig. 4 e), deposition thickness 150nm is then at N ₂In 1050 ℃ annealing 20 minutes.

5, adopting microflute, contact hole, semi-girder is that the mask plate of one carries out photoetching (shown in Fig. 4 f), if a side of the chip 1 of semi-girder 4 settings can not be provided with microflute, to Si ₃N ₄Carry out CHF ₃+ SF ₆(fluoroform+sulfur hexafluoride) reactive ion etching etches away the Si on microflute 14 and the force sensing resistance contact hole 15 ₃N ₄, etch away cantilever arm Si on every side simultaneously ₃N ₄

6, by electron beam transpiration chromium/gold (Cr/Au) thermometal film 16 (shown in Fig. 4 g), chromium thickness is 40nm, be used for making gold preferably attached on the chip substrate, golden thickness 400nm adopts gold rather than aluminium to be because the corrosion that gold can be resisted potassium hydroxide (KOH).

7, adopt metal mask plate (shown in Fig. 4 h), after the photoetching, corroding metal is finished the shaping of metal wire 17;

8, carry out the scribing (shown in Fig. 4 i) of single-sensor on entire chip 1, first scribing guarantees not damage semi-girder in the scribing processes before carrying out the potassium hydroxide corrosion.

9, carry out potassium hydroxide corrosion silicon, discharge semi-girder (shown in Fig. 4 j), utilize the character of potassium hydroxide, under sufficiently long etching time the anisotropy salient angle corrosion of silicon, silicon below the semi-girder can corrode totally fully, the about 60 μ m of the groove depth after the corrosion.

10, metal and silicon in the force sensing resistance contact hole are carried out Alloying Treatment, make it form Ohmic contact, alloy condition: 320 ℃, 20 minutes.

11, be single-sensor with entire chip from above-mentioned scribing sliver.

12, a semi-girder in per two semi-girders is promptly measured semi-girder 4 ' the surperficial coating sensitive layer.

In the said method,

Step 1, when silicon chip surface carried out the plasma enhanced CVD silicon nitride, its thickness can be 100～1000nm; The oxidated layer thickness of soi wafer can be 200～800nm, and device layer thickness can be 100～500nm.

Step 1, low pressure chemical vapor deposition polysilicon are during as the force sensing resistance layer, and its thickness can be 100～500nm; The thickness of silicon nitride or monox protective seam has determined the thickness of semi-girder, and the thickness of semi-girder has determined its sensitivity, can be found out by formula (4).

Step 2 is injected when mixing monocrystalline silicon or polysilicon front boron ion, and the concentration of injecting the boron ion can be 5 * 10 ¹³Cm ^-2～5 * 10 ¹⁵Cm ^-2, energy 30keV～80keV; Doping content is high more, and the noise of semi-girder is low more, but sensitivity reduces simultaneously.Ion implantation energy determines the depth that the boron ion spreads in resistive layer, thereby influences the sensitivity of semi-girder.

Step 4, during the plasma enhanced CVD silicon nitride, deposition thickness can be 100～1000nm, then in nitrogen 900～1100 ℃ annealing 20～30 minutes, deposition thickness has determined the thickness of semi-girder, and the thickness of semi-girder has determined its sensitivity, can be found out by formula (4).

Step 5, the thickness of chromium/golden thermometal film can suitably be adjusted.

In the above-mentioned method for making, after the chip photoetching, no matter be etching in gas, still in liquid, corrode that its employed gas or liquid all can change as required.

In the foregoing description, the quantity of semi-girder 4 can be according to the needs setting of the project of measurement, but its quantity should be even number, promptly two semi-girders are one group, form a sensing unit independently with four force sensing resistances that on two semi-girders and chip substrate, are provided with, finish a measurement project, therefore, have two semi-girders on the chip, just can form a sensor; If many group semi-girders are set, then form array-type sensor, sensor can not be provided with microflute, makes semi-girder be positioned at a side (as shown in Figure 3) of chip, also microflute can be set, and makes semi-girder be positioned at microflute both sides (as shown in Figure 1).

The present invention can by front etch technology and silicon～glass (polymer) bonding techniques with Design of Cantilever Beam, Preparation can be directly used in the detection of liquid biological molecule like this in the flowable microflute of liquid.

No matter the modular or array pressure drag cantilever beam of the present invention is to be applied on the gas sensor, or bio-sensing On the device, all will reduce device size, improve device sensitivity and realize that the multifunctionality performance of sensor is heavy Act on. The beam type sensor is in environmental monitoring, clinical diagnosis and treatment, new drug development, food security, The fields such as industrial processes control, military affairs are with a wide range of applications.

Claims (13)

1; a kind of micro-cantilever beam sensor; it comprises a chip; described chip is provided with at least one group of sensing unit; described sensing unit is made up of four identical force sensing resistances and two semi-girders of forming Wheatstone bridge; wherein two described force sensing resistances are positioned on the substrate of described chip; two other lays respectively on described two semi-girders; one of them described semi-girder is as measuring semi-girder; another is as the reference semi-girder; it is characterized in that: described chip is provided with a microflute; described semi-girder is arranged in the described microflute; the material of described force sensing resistance adopts monocrystalline silicon or polysilicon; be doped with the boron ion at described monocrystalline silicon or polysilicon front; on described force sensing resistance; lower surface is provided with silicon nitride or monox protective seam; the described semi-girder of common composition, described measurement semi-girder surface is provided with sensitive layer.

2, micro-cantilever beam sensor as claimed in claim 1 is characterized in that: described sensitive layer is the high molecule sensitivity material.

3, micro-cantilever beam sensor as claimed in claim 1 is characterized in that: described sensitive layer is a bioactive molecule.

4, as claim 1 or 2 or 3 described micro-cantilever beam sensors, it is characterized in that: described semi-girder is long 50～500 μ m, wide 10～100 μ m, the rectangle of thick 100～5000nm.

5, as claim 1 or 2 or 3 described micro-cantilever beam sensors, it is characterized in that: described force sensing resistance is of a size of long 20～200 μ m, wide 5～50 μ m.

6, micro-cantilever beam sensor as claimed in claim 4 is characterized in that: described force sensing resistance is of a size of long 20～200 μ m, wide 5～50 μ m.

7, a kind of method for making of micro-cantilever beam sensor is characterized in that it may further comprise the steps:

(1) adopt soi wafer, and the attenuate device layer is as chip substrate with oxide layer, single-crystal silicon device layer; Perhaps adopt single-sided polishing p type silicon chip, carry out after routine cleans, at silicon chip surface plasma enhanced CVD silicon nitride, then at silicon nitride surface low pressure chemical vapor deposition polysilicon as chip substrate;

(2) monocrystalline silicon or the injection of polysilicon front boron ion are mixed;

(3) with mask plate the chip through step (2) is carried out the photoetching first time,, form force sensing resistance through etching;

(4) chip surface through step (3) is passed through the plasma enhanced CVD silicon nitride, in AN;

(5) with mask plate the chip through step (4) is carried out the photoetching second time,, form force sensing resistance contact hole and semi-girder through etching;

(6) chip surface through step (5) is passed through electron beam, sputter chromium/golden thermometal film;

(7) with mask plate the chip through step (6) is carried out photoetching for the third time,, form the metal wire that connects each force sensing resistance through corrosion;

(8) on entire chip, carry out the scribing of single-sensor;

(9) with the chip of potassium hydroxide corrosion, discharge semi-girder through step (8);

(10) metal wire in the force sensing resistance contact hole on the chip and chip substrate are carried out alloy treatment;

(11) be single-sensor with the entire chip sliver;

(12) a semi-girder surface in per two semi-girders is provided with sensitive layer.

8, the method for making of a kind of micro-cantilever beam sensor as claimed in claim 7 is characterized in that: step (5) wherein forms the microflute on the chip when forming force sensing resistance contact hole and semi-girder.

9, the method for making of a kind of micro-cantilever beam sensor as claimed in claim 7 is characterized in that: step (1) wherein, and the oxidated layer thickness of soi wafer is 200～800nm, device layer thickness is 100～500nm.

10, the method for making of a kind of micro-cantilever beam sensor as claimed in claim 7 is characterized in that: step (1) wherein, when silicon chip surface carried out the plasma enhanced CVD silicon nitride, the thickness of silicon nitride was 100～1000nm.

11, the method for making of a kind of micro-cantilever beam sensor as claimed in claim 7 is characterized in that: step (1) wherein, when the low pressure chemical vapor deposition polysilicon, the thickness of polysilicon is 100～500nm.

12, the method for making of a kind of micro-cantilever beam sensor as claimed in claim 7 is characterized in that: step (2) wherein, monocrystalline silicon or polysilicon front boron ion to be injected when mixing, and the concentration of injecting the boron ion is 5 * 10 ¹³Cm ^-2～5 * 10 ¹⁵Cm ^-2, inject energy 30keV～80keV.

13, the method for making of a kind of micro-cantilever beam sensor as claimed in claim 7, it is characterized in that: step (4) wherein, during the plasma enhanced CVD silicon nitride, silicon nitride thickness is 100～1000nm, then in nitrogen 900～1100 ℃ annealing 20～30 minutes.

Images