CN104833996A - Array-type gamma irradiation dosimeter of FBAR structure on diaphragm - Google Patents

Abstract

The invention discloses an array-type gamma irradiation dosimeter of a FBAR structure on a diaphragm. The array-type gamma irradiation dosimeter comprises a detection element, a composite thin film, and a Si substrate. The detection element is disposed on the upper part of the composite thin film, and the composite thin film is used to support the detection element, and the Si substrate is disposed on the lower part of the composite thin film. The detection element comprises a plurality of FBAR, which are in an array-type arrangement, and are disposed on the composite thin film. Each of the FBAR comprises, from bottom to top, a bottom electrode, a piezoelectric layer, and a top electrode sequentially. An irradiation sensitive layer is disposed between each of the piezoelectric layers and each of the bottom electrodes, or is disposed between each of the piezoelectric layers and each of the top electrodes, and the bottom electrodes are tightly attached to the upper surface of the composite thin film. The Si substrate is provided with a plurality cavities, which are respectively corresponding to the irradiation sensitive layers in a vertical direction. The cavities are used to form the volume acoustic wave reflection interfaces, and the composite thin film areas corresponding to the cavities are the composite thin film suspension areas. The array-type gamma irradiation dosimeter has advantages of small size, high sensitivity, good temperature stability, good manufacturability, and ability of detecting irradiation dose distribution.

Description

The array gamma irradiation quantimeter of FBAR structure on diaphragm

Technical field

The invention belongs to mems device field, be specifically related to FBAR (thin film bulk acoustic resonator on a kind of diaphragm, film bulk acoustic-wave resonators) array gamma irradiation quantimeter, this array gamma irradiation quantimeter have size little, highly sensitive, the advantages such as irradiation dose distribution, the good and manufacturability of temperature stability are good can be detected.

Technical background

Ionizing radiation sensing has a large amount of application, and in large-scale high-energy physics experiment, high dosage irradiation test is the important means understanding silicon-based electronic devices degeneration.In nuclear material detection and security application, because irradiation bomb may partly be covered, need the sensor of low dosage.In uranology field, need flux and the direction of measuring high-energy irradiation.In the radiation therapy of Therapeutic cancer, need exact position and the size of determining irradiation incidence.At present, existing multiple sensors is used for the detection of irradiation.

Thin film bulk acoustic resonator (FBAR, thin-film bulk acoustic wave resonators) is a kind of novel miniature electro-acoustic resonator, has the features such as high sensitivity, high operate frequency and low-power consumption.Substitute traditional gamma irradiation detecting element with FBAR and the distribution in array, a kind of novel high-frequency resonant formula gamma irradiation quantimeter can be built, meet the demand of array, high sensitivity, microminaturization gamma irradiation dose measurement.Its principle of work is: irradiation makes the capacity plate antenna (C of FBAR ₀) increase, thus reduce the resonance frequency of FBAR; Suitable radio circuit or vector network analyzer is utilized to measure the resonance frequency shift of FBAR, the measurement of real irradiation dose; In array, the FBAR of distribution can realize the detection of irradiation dose distribution.

Subsidized a kind of irradiation sensor based on FBAR of research by US National Aeronautics and Space Administration, this has researched and proposed two kinds of structures: one is that radiation sensitive is placed between piezoelectric layer and hearth electrode, and radiation sensitive layer adopts LPCVD process deposits; Another kind is that radiation sensitive is placed between piezoelectric layer and top electrode, and radiation sensitive layer adopts pecvd process deposition, it is characterized in that adopting through hole type FBAR as detecting element.The shortcoming of the program is: one, FBAR does not have temperature compensating layer, and the impact of temperature on FBAR resonance frequency is larger; Two, owing to only having single detecting element, therefore the distribution of irradiation dose cannot be detected.

It is CN1138901 that Rados Technology OY discloses publication number, and publication date is Finland's patent of invention document on Dec 25th, 1996, and the document relates to a kind of method utilizing the quantimeter of band floating gate mosfet transistor to measure ionizing radiation.The major defect of the program is: for needing a large inductance during radio communication, because which limit the miniaturization potential of this device.

It is CN2369254 that Beijing Radiomedicine Inst. discloses publication number, publication date is the Chinese invention patent document on March 15th, 2000, the document relates to a kind of thermoluminescent personal dosimeter, in order to determine the dosage that irradiation consequence is subject to, needing to heat to thermoluminescent dosemeter and adopting spectrometer measurement to launch light intensity.The shortcoming of the program is: need effective aftertreatment accurately could determine the dosage that irradiation absorbs.

Summary of the invention

The present invention is in order to solve above-mentioned technological deficiency, provide the array gamma irradiation quantimeter meter of FBAR structure on a kind of diaphragm, the array gamma irradiation quantimeter meter of this kind of structure is except having high sensitivity (frequency shift (FS)/ionization dosage is in 1000kHz/krad magnitude), low-power consumption (FBAR has low-power consumption a little), manufacturing is good (is easy to single-chip integration with CMOS technology compatibility, do not need to use large inductance), high operate frequency (resonance frequency is in GHz magnitude), the impact of temperature on FBAR sensitivity can also be improved, add the physical strength of device, the array gamma irradiation quantimeter of FBAR structure on diaphragm, is expected the demand meeting array, high sensitivity, microminaturization gamma irradiation dose measurement.

For achieving the above object, the present invention takes following technical scheme:

The array gamma irradiation quantimeter of FBAR structure on diaphragm, it is characterized in that: comprise detecting element, laminated film and Si pedestal, detecting element is positioned at above laminated film, laminated film is for supporting detecting element, and Si pedestal is positioned at below laminated film; Detecting element includes some rectangular array and is distributed in FBAR above laminated film, FBAR comprises hearth electrode, piezoelectric layer and top electrode from down to up successively, radiation sensitive layer is arranged between piezoelectric layer and hearth electrode or is arranged between piezoelectric layer and top electrode, and hearth electrode is close to laminated film upper surface; Si pedestal is provided with some cavitys, and cavity and radiation sensitive layer position one_to_one corresponding in the vertical, cavity is for the formation of bulk acoustic wave reflecting interface.

The quantity of described FBAR is N × M, N, M is positive integer.

Described FBAR shape can be arbitrary polygon.

Laminated film region corresponding above described cavity is the unsettled region of laminated film.

The FBAR of described detecting element is connected with pad by lead-in wire.

Described lead-in wire comprises hearth electrode lead-in wire and goes between with top electrode, and pad comprises hearth electrode pad and top electrode pad, and the hearth electrode of FBAR is connected with hearth electrode pad by hearth electrode lead-in wire, and the top electrode of FBAR is connected with top electrode pad by top electrode lead-in wire.

For the syndeton of FBAR, pad and lead-in wire, following connected mode can be comprised:

The first connected mode: the hearth electrode often arranging FBAR is all connected with same hearth electrode pad by same hearth electrode lead-in wire, often the top electrode of row FBAR all passes through same top electrode and goes between and be connected with same top electrode pad; Or often the hearth electrode of row FBAR all passes through same hearth electrode lead-in wire and is connected with same hearth electrode pad, and the top electrode often arranging FBAR is all gone between by same top electrode and is connected with same top electrode pad.

Based on the first connected mode:

If radiation sensitive is placed between piezoelectric layer and hearth electrode, a part for piezoelectric layer bottom surface is close to radiation sensitive layer upper surface, another part of piezoelectric layer bottom surface is coated radiation sensitive layer side and hearth electrode side extend to the unsettled region upper surface of laminated film to both sides, a part for top electrode bottom surface is close to the upper surface of piezoelectric layer, and another part of top electrode bottom surface is coated piezoelectric layer side extend to the unsettled region upper surface of laminated film to both sides;

If radiation sensitive is placed between piezoelectric layer and top electrode, a part for piezoelectric layer bottom surface is close to hearth electrode upper surface, another part of piezoelectric layer bottom surface is coated hearth electrode side extend to the unsettled region upper surface of laminated film to both sides, a part for top electrode bottom surface is close to the upper surface of radiation sensitive layer, and another part of top electrode bottom surface is coated radiation sensitive layer side and piezoelectric layer side extend to the unsettled region upper surface of laminated film to both sides.

The second connected mode: the hearth electrode often arranging FBAR is all connected in same hearth electrode bus by respective hearth electrode lead-in wire, and often the top electrode of row FBAR is all connected in same top electrode bus by respective top electrode lead-in wire; Or often the hearth electrode of row FBAR is all connected in same hearth electrode bus by respective hearth electrode lead-in wire, the top electrode often arranging FBAR is all connected in same top electrode bus by respective top electrode lead-in wire; Every bar hearth electrode bus connects a hearth electrode pad, and every bar top electrode bus connects a top electrode pad.

Based on the second connected mode:

If radiation sensitive is placed between piezoelectric layer and hearth electrode, a part for piezoelectric layer bottom surface is close to radiation sensitive layer upper surface, another part of piezoelectric layer bottom surface is coated radiation sensitive layer side and hearth electrode side extend to the unsettled region upper surface of laminated film to side, a part for top electrode bottom surface is close to the upper surface of piezoelectric layer, and another part of top electrode bottom surface is coated piezoelectric layer side extend to the unsettled region upper surface of laminated film to both sides;

If radiation sensitive is placed between piezoelectric layer and top electrode, a part for piezoelectric layer bottom surface is close to hearth electrode upper surface, another part of piezoelectric layer bottom surface is coated hearth electrode side extend to the unsettled region upper surface of laminated film to side, a part for top electrode bottom surface is close to the upper surface of radiation sensitive layer, and another part of top electrode bottom surface is coated radiation sensitive layer side and piezoelectric layer side extend to the unsettled region upper surface of laminated film to both sides.

At top electrode bus and hearth electrode bus infall in the second connected mode, hearth electrode bus is covered with piezoelectric layer, top electrode bus is passed through from the upper surface of this piezoelectric layer, due to this piezoelectric layer, there are insulating property thus achieve the insulation of top electrode bus and hearth electrode bus, piezoelectric layer in this piezoelectric layer and FBAR is the same material with same thickness, therefore can by being formed with primary depositing and patterning process.

Described hearth electrode, hearth electrode lead-in wire and hearth electrode pad are all the conductor materials of the same race with same thickness, therefore can by being formed with primary depositing and patterning process; Top electrode, top lead-in wire and top electrode pad are all the conductor materials of the same race with same thickness, therefore can by being formed with primary depositing and patterning process.Due to the part that the unsettled region of laminated film is laminated film, the unsettled region of laminated film is continuous, a complete plane, hearth electrode lead-in wire and top electrode lead-in wire can at laminated film region upper surface flexible routes, and hearth electrode pad and top electrode pad are all arranged at the laminated film upper surface that Si pedestal correspondence supports.

For radiation sensitive layer, be defined as further:

Described radiation sensitive layer can use Si ₃n ₄or SiO ₂material, and use PECVD or LPCVD process layer to deposit.

For cavity, be defined as further:

Described cavity is formed by deep reaction ion etching after the back-patterned formation etching window of silicon substrate.Si pedestal and the membrane-enclosed space of THIN COMPOSITE form cavity, fill air in cavity.The interface of cavity and laminated film is for the formation of the bulk acoustic wave reflecting interface of FBAR.

In order to obtain high performance FBAR, sound wave need be limited in the FBAR be made up of hearth electrode-piezoelectric layer-top electrode.According to transmission line theory, when load be zero or infinitely great time, incident wave will be totally reflected, and the acoustic impedance of air is approximately equal to zero, can as good bulk acoustic wave reflection boundary.And top electrode generally contacts with air in FBAR, naturally form good bulk acoustic wave reflecting interface, hearth electrode because being placed in so need organizator acoustic reflection interface artificially above laminated film, cavity-SiO in the present invention ₂layer is bulk acoustic wave reflecting interface.

For laminated film, be defined as further:

Described laminated film is square diaphragm, and laminated film comprises SiO ₂layer and Si ₃n ₄layer, SiO ₂layer is connected with Si pedestal, Si ₃n ₄layer is positioned at SiO ₂above layer, the thickness of laminated film is SiO ₂layer and Si ₃n ₄the thickness sum of layer.

Described laminated film is as the supporting layer of FBAR.

SiO in described laminated film ₂layer has positive temperature coefficient (PTC), is prepared by CVD technique; The piezoelectric layer of FBAR has negative temperature coefficient; The SiO in the unsettled region of laminated film ₂layer and the piezoelectric layer compound of FBAR, carry out temperature compensation, can improve the temperature stability of FBAR.

By FBAR series resonance frequency f _sand the relational expression between piezoelectric layer elasticity coefficient c: know, the elasticity coefficient c of piezoelectric layer and series resonance frequency f _sbe directly proportional.Interaction force between its interior atoms of the piezoelectric layer of existing majority generally all shows negative temperature characteristic, and namely along with temperature raises, interatomic interaction force weakens, and causes the elasticity coefficient of piezoelectric layer to diminish.And the resonance frequency of FBAR and the elasticity coefficient of piezoelectric layer proportional, therefore, along with the rising of temperature, the resonance frequency of FBAR reduces.For reducing the impact of this temperature-frequency drift characteristic, temperature compensation must be carried out to improve its temperature stability to FBAR.Due to SiO ₂the Young modulus of layer increases with the rising of temperature, and namely its temperature coefficient is on the occasion of (about+85/ DEG C), therefore, as the SiO of positive temperature coefficient (PTC) ₂layer, at the piezoelectric layer compound tense with negative temperature coefficient, can reduce temperature drift each other, therefore adopts SiO ₂layer is as the understructure in laminated film.

Described SiO ₂layer is as self-stopping technology layer during silicon substrate back-etching; Due to etchant SiO ₂speed much smaller than etching Si speed, can guarantee that the etching of silicon substrate can not to SiO ₂/ Si ₃n ₄the thickness of flexible sheet has an impact.

Described Si ₃n ₄layer and SiO ₂layer compound, can be used for the physical strength strengthening laminated film.Meanwhile, Si ₃n ₄layer is insulating material, and the hearth electrode in FBAR directly can sputter at Si ₃n ₄on layer.

Because the resonance frequency impact of Si on FBAR is very large, FBAR can be made to produce multiple mode of resonance, be unfavorable for the detection of irradiation signal, therefore Si layer can not be used as the superstructure of laminated film.Si ₃n ₄layer has the excellent physical property such as high compactness, high-k and high insulation resistance and the excellent mechanical property such as fatigue resistance is high, resistance to fracture is strong; And thinner Si ₃n ₄layer can not have an impact to the resonance frequency of FBAR.In order to improve the physical strength of device, therefore adopt Si ₃n ₄layer is as the superstructure of laminated film.

Beneficial effect of the present invention is as follows:

The present invention, while realizing array gamma irradiation quantimeter high sensitivity and high operate frequency, can also improve the temperature stability of FBAR, and adopt technique comparatively simply to carry on the back chamber etching technics and form laminated film, device physical strength is large, and wiring is convenient; The array gamma irradiation quantimeter of FBAR structure on diaphragm, is expected the demand meeting array, high sensitivity, microminaturization gamma irradiation dose measurement.

Accompanying drawing explanation

Fig. 1-2 is respectively the plan structure schematic diagram that FBAR of the present invention is the first connected mode difform;

Fig. 3 is the A-A ' cross sectional representation of Fig. 1;

The main manufacturing process steps schematic diagram that Fig. 4-11 is structure shown in Fig. 3;

Figure 12-13 is respectively the plan structure schematic diagram that FBAR of the present invention is difform the second connected mode;

Figure 14 is the B-B ' cross sectional representation of Figure 12;

Figure 15-22 is the main manufacturing process steps schematic diagram of shown structure;

Wherein, Reference numeral is: 1 detecting element, 2 hearth electrode pads, 3 top electrode pads, 4 hearth electrode lead-in wires, 5 top electrode lead-in wires, 6 laminated films, the 7 unsettled regions of laminated film, 8Si pedestal, 9 cavitys, 10Si ₂o layer, 11Si ₃n ₄layer, 12 hearth electrodes, 13 piezoelectric layers, 14 radiation sensitive layers, 15 top electrodes, 16 hearth electrode buses, 17 top electrode buses.

Embodiment

Below in conjunction with accompanying drawing, the present invention is elaborated:

On diaphragm, the array gamma irradiation quantimeter of FBAR structure, comprises detecting element 1, laminated film 6 and Si pedestal 8, and detecting element 1 is above laminated film 6, and laminated film 6 is positioned at below laminated film 6 for supporting detecting element 1, Si pedestal 8; Detecting element 1 includes some rectangular array and is distributed in FBAR above laminated film 6, FBAR comprises hearth electrode 12, piezoelectric layer 13 and top electrode 15 from down to up successively, radiation sensitive layer 14 is arranged between piezoelectric layer 13 and hearth electrode 12 or is arranged between piezoelectric layer 13 and top electrode 15, and hearth electrode 12 is close to laminated film 6 upper surface; Si pedestal 8 is provided with some cavitys 9, and cavity 9 and radiation sensitive layer 14 position one_to_one corresponding in the vertical, cavity 9 is for the formation of bulk acoustic wave reflecting interface.

The quantity of described FBAR is N × M, N, M is positive integer, and FBAR shape can be any regular polygon, can be the square as shown in Fig. 1,12, also can be the regular pentagon etc. shown in Fig. 2,13; The quantity of the FBAR of detecting element 1 is N × M and the distribution of rectangular array, and N, M are positive integer.

The FBAR of described detecting element 1 is connected with pad by lead-in wire.

Described lead-in wire comprises hearth electrode lead-in wire 4 and goes between 5 with top electrode, pad comprises hearth electrode pad 2 and top electrode pad 3, the hearth electrode 12 of FBAR is connected with hearth electrode pad 2 by hearth electrode lead-in wire 4, and the top electrode 15 of FBAR is connected with top electrode pad 3 by top electrode lead-in wire 5.

For the syndeton of FBAR, pad and lead-in wire, following connected mode can be comprised:

As shown in figs. 1-11, the first connected mode:

The hearth electrode 12 often arranging FBAR is all connected with same hearth electrode pad 2 by same hearth electrode lead-in wire 4, and often the top electrode 15 of row FBAR is all connected with same top electrode pad 3 by same top electrode lead-in wire 5; Or often the hearth electrode 12 of row FBAR is all connected with same hearth electrode pad 2 by same hearth electrode lead-in wire 4, the top electrode 15 often arranging FBAR is all connected with same top electrode pad 3 by same top electrode lead-in wire 5.

Based on the first connected mode:

If radiation sensitive layer 14 is placed between piezoelectric layer 13 and hearth electrode 12, a part for piezoelectric layer 13 bottom surface is close to radiation sensitive layer 14 upper surface, another part of piezoelectric layer 13 bottom surface is coated radiation sensitive layer 14 side and hearth electrode 12 side extend to laminated film unsettled region 7 upper surface to both sides, a part for top electrode 15 bottom surface is close to the upper surface of piezoelectric layer 13, and another part of top electrode 15 bottom surface is coated piezoelectric layer 13 side extend to laminated film unsettled region 7 upper surface to both sides;

If radiation sensitive layer 14 is placed between piezoelectric layer 13 and top electrode 15, a part for piezoelectric layer 13 bottom surface is close to hearth electrode 12 upper surface, another part of piezoelectric layer 13 bottom surface is coated hearth electrode 12 side extend to laminated film unsettled region 7 upper surface to both sides, a part for top electrode 15 bottom surface is close to the upper surface of radiation sensitive layer 14, and another part of top electrode 15 bottom surface is coated radiation sensitive layer 14 side and piezoelectric layer 13 side extend to laminated film unsettled region 7 upper surface to both sides.

As shown in Figure 12-22, the second connected mode:

The hearth electrode 12 often arranging FBAR is all connected in same hearth electrode bus 16 by respective hearth electrode lead-in wire 4, and often the top electrode 15 of row FBAR is all connected in same top electrode bus 17 by respective top electrode lead-in wire 5; Or often the hearth electrode 12 of row FBAR is all connected in same hearth electrode bus 16 by respective hearth electrode lead-in wire 4, the top electrode 15 often arranging FBAR is all connected in same top electrode bus 17 by respective top electrode lead-in wire 5; Every bar hearth electrode bus 16 connects a hearth electrode pad 2, and every bar top electrode bus 17 connects a top electrode pad 3.

Based on the second connected mode:

If radiation sensitive layer 14 is placed between piezoelectric layer 13 and hearth electrode 12, a part for piezoelectric layer 13 bottom surface is close to radiation sensitive layer 14 upper surface, another part of piezoelectric layer 13 bottom surface is coated radiation sensitive layer 14 side and hearth electrode 12 side extend to laminated film unsettled region 7 upper surface to side, a part for top electrode 15 bottom surface is close to the upper surface of piezoelectric layer 13, and another part of top electrode 15 bottom surface is coated piezoelectric layer 13 side extend to laminated film unsettled region 7 upper surface to both sides;

If radiation sensitive layer 14 is placed between piezoelectric layer 13 and top electrode 15, a part for piezoelectric layer 13 bottom surface is close to hearth electrode 12 upper surface, another part of piezoelectric layer 13 bottom surface is coated hearth electrode 12 side extend to laminated film unsettled region 7 upper surface to side, a part for top electrode 15 bottom surface is close to the upper surface of radiation sensitive layer 14, and another part of top electrode 15 bottom surface is coated radiation sensitive layer 14 side and piezoelectric layer 13 side extend to laminated film unsettled region 7 upper surface to both sides.

At top electrode bus 17 and hearth electrode bus 16 infall in the second connected mode, hearth electrode bus 16 is covered with piezoelectric layer 13, top electrode bus 17 is passed through from the upper surface of this piezoelectric layer 13, due to this piezoelectric layer 13, there are insulating property thus achieve the insulation of top electrode bus 17 and hearth electrode bus 16, this piezoelectric layer 13 is the same material with same thickness with the piezoelectric layer 13 in FBAR, therefore can by being formed with primary depositing and patterning process.

Described hearth electrode 12, hearth electrode lead-in wire 4 and hearth electrode pad 2 are all the conductor materials of the same race with same thickness, therefore can by being formed with primary depositing and patterning process; Top electrode 15, top lead-in wire and top electrode pad 3 are all the conductor materials of the same race with same thickness, therefore can by being formed with primary depositing and patterning process.Due to the part that the unsettled region 7 of laminated film is laminated films 6, the unsettled region of laminated film 7 is continuous, complete planes, hearth electrode lead-in wire 4 and top electrode lead-in wire 5 can at laminated film region upper surface flexible routes, and hearth electrode pad 2 and top electrode pad 3 are all arranged at laminated film 6 upper surface that Si pedestal 8 correspondence supports.

For radiation sensitive layer 14, be defined as further:

Described radiation sensitive layer 14 can use Si ₃n ₄or SiO ₂material, and use PECVD or LPCVD process layer to deposit.Radiation sensitive layer 14 can be placed between piezoelectric layer 13 and hearth electrode 12, also can be placed between piezoelectric layer 13 and top electrode 15.

For cavity 9, be defined as further:

Fig. 7 is the back of the body TV structure schematic diagram of one of them unit of the present invention, and described cavity 9 is formed by deep reaction ion etching after the back-patterned formation etching window of silicon substrate.The space that Si pedestal 8 and laminated film 6 surround forms cavity 9, fills air in cavity 9.

The interface of described cavity 9 and laminated film 6 is for the formation of the bulk acoustic wave reflecting interface of FBAR.

For laminated film 6, be defined as further:

Described laminated film 6 is square diaphragms, and laminated film 6 comprises SiO ₂layer 10 and Si ₃n4 layer 11, SiO ₂layer 10 is connected with Si pedestal 8, Si ₃n ₄layer 11 is positioned at SiO ₂above layer 10, the thickness of laminated film 6 is SiO ₂layer 10 and Si ₃n ₄the thickness sum of layer 11.

Described laminated film 6 is as the supporting layer of FBAR.

SiO in described laminated film 6 ₂layer 10 has positive temperature coefficient (PTC), is prepared by CVD technique; The piezoelectric layer 13 of FBAR has negative temperature coefficient; The SiO in the unsettled region 7 of laminated film ₂layer 10 and piezoelectric layer 13 compound of FBAR, carry out temperature compensation, can improve the temperature stability of FBAR.

Gamma irradiation incides on radiation sensitive layer 14 and piezoelectric layer 13, produces electron-hole pair (EHPs, electron-hole pairs), causes ionization damage.The density of electron-hole pair is directly proportional to the energy of transfer.After electron-hole pair produces, fraction electronics and hole will soon compounds.Because electronics has higher mobility, can obtain than hole-recombination faster, cause in unnecessary hole migration to the deep hole trap of radiation sensitive layer 14 or radiation sensitive layer 14/ piezoelectric layer 13 interface.Transporting of hole adopts the electric charge " jump " (charge " hopping ") in dielectric between surface imperfection point to characterize.Herein, the electric charge of catching is accumulated, and changes the surface potential of piezoelectric layer 13 or radiation sensitive layer 14, makes capacity plate antenna (C ₀) increase, thus reduce the resonance frequency of FBAR.

The model of the irradiation effect in solid material can be set up.Quantity (being also " propagation constant, generation the constant ") g of the EHPs that the every dosage of ionization photon unit volume from target material produces ₀, provided by following formula:

$g_0\left[\frac{\#\mathrm{ehp}}{{\mathrm{cm}}^3\·\mathrm{rad}}\right]=100\left[\frac{\mathrm{erg}}{g}\right]\left[\frac{1}{\mathrm{rad}}\right]\·\frac{1}{1.6\×{10}^{-12}}\left[\frac{\mathrm{eV}}{\mathrm{erg}}\right]\·\frac{1}{E_p}\left[\frac{\#\mathrm{ehp}}{\mathrm{eV}}\right]\·\mathrm{\ρ}\left[\frac{g}{{\mathrm{cm}}^3}\right]---\left(1\right)$

In formula, E _pbe the average free energy (being about 2 times of band gap) needed for ionization, ρ is the density of target material.Within any given time, the fraction hole escaping recombination process can represent with the hole continuity equation of one dimension (x direction):

$\frac{\∂p}{\∂t}=\frac{{\∂f}_{p,x}}{\∂x}+G_p-R_p---\left(2\right)$

In formula, p is the concentration (cm in hole ^-3), f _p,xthe flux in hole, G _pthe generation speed (cm in hole ^-3s ^-1), R _pthe hole-recombination speed (cm postponed ^-3s ^-1).If suppose that this device is in stable state and postpones recombination rate can ignore, formula (2) is rewritten as:

$\frac{{\∂f}_{p,x}}{\∂x}=G_p---\left(3\right)$

In formula, radiation-induced hole generation rate is provided by following formula:

$G_p=\stackrel{\·}{D}{g}_0{f}_y\left(\right|E_x\left|\right)---\left(4\right)$

In formula, radiation dose rate, g ₀the propagation constant that formula (1) provides, f _ybe the electric charge yield relevant with internal field in device, can approximate representation be:

$f_y\left(\stackrel{\→}{E}\right)~\left(\frac{\left|\stackrel{\→}{E}\right|}{|\stackrel{\→}{E}+E_0|}\right)---\left(5\right)$

In formula, E ₀it is threshold field constant.Simultaneous formula (3) also uses boundary condition, can solve the flux in hole at two different directions of an electric field:

|f _p,x(x)|＝G _p·x E _x＞0

(6)

|f _p,x(x)|＝G _p·(t _p-x) E _x＜0

In formula, t _ddielectric thickness.Finally, the hole capture speed of semiconductor-dielectric near interface can be expressed as:

$\frac{d_{n_{\mathrm{ot}}}\left(x\right)}{\mathrm{dt}}=(n_t\left(x\right)-n_{\mathrm{ot}}\left(x\right))\·{\mathrm{\σ}}_p\·\left|f_{p,x}\left(x\right)\right|-R_{n_{\mathrm{ot}}}---\left(7\right)$

In formula, n _otand n _tcatch the density in hole and the density of capture point, σ respectively _phole Capture Cross Section (cm ²).Composite factor represent the clearance of catching hole from system.Because again characterizing after last irradiation five hours finds do not have deviation with previous measurement, therefore suppose that composite factor is negligible.

The main manufacturing process steps schematic diagram of the first connected mode of the present invention, comprises as Fig. 4-11 eight main technological steps.Fig. 4 is initial silicon substrate; In Figure 5, one deck SiO is formed in surface on a silicon substrate by dry-wet-dry oxidation ₂layer 10; In figure 6, by LPCVD at SiO ₂layer 10 upper surface form one deck Si ₃n ₄layer 11, SiO ₂layer 10 and Si ₃n ₄layer 11 constitutes laminated film 6; In the figure 7, by magnetron sputtering and ultrasonic stripping at Si ₃n ₄layer 11 upper surface forms Pt hearth electrode 12, hearth electrode lead-in wire 4, hearth electrode pad 2; In fig. 8, AlN piezoelectric layer 13 is formed by reaction magnetocontrol sputtering and TMAH solution corrosion at hearth electrode 12 upper surface; In fig .9, be etched in AlN piezoelectric layer 13 upper surface by PECVD deposition and RIE and form Si ₃n ₄radiation sensitive layer 14; In Fig. 10, by magnetron sputtering and wet etching at Si ₃n ₄the upper surface of radiation sensitive layer 14 forms Al top electrode 15, top electrode lead-in wire 5 and top electrode pad 3; In fig. 11, by deep reaction ion etching, local etching is carried out to the back side of silicon substrate, form cavity 9.

The main manufacturing process steps schematic diagram of the second connected mode of the present invention, comprises as Figure 15-22 eight main technological steps.Figure 15 is initial silicon substrate; In figure 16, one deck SiO is formed in surface on a silicon substrate by dry-wet-dry oxidation ₂layer 10; In fig. 17, by LPCVD at SiO ₂layer 10 upper surface form one deck Si ₃n ₄layer 11, SiO ₂layer 10 and Si ₃n ₄layer 11 constitutes laminated film 6; In figure 18, by magnetron sputtering and ultrasonic stripping at Si ₃n ₄layer 11 upper surface forms Pt hearth electrode 12, hearth electrode lead-in wire 4, hearth electrode bus 16, hearth electrode pad 2; In Figure 19, form AlN piezoelectric layer 13 by reaction magnetocontrol sputtering and TMAH solution corrosion at hearth electrode 12 upper surface, and also form AlN piezoelectric layer 13 at hearth electrode bus 16 and top electrode bus 17 infall; In fig. 20, be etched in AlN piezoelectric layer 13 upper surface by PECVD deposition and RIE and form radiation sensitive layer 14; In figure 21, by magnetron sputtering and wet etching at Si ₃n ₄the upper surface of radiation sensitive layer 14 forms Al top electrode 15, top electrode lead-in wire 5, top electrode bus 17 and top electrode pad 3; In fig. 22, by deep reaction ion etching, local etching is carried out to the back side of silicon substrate, form cavity 9.

Claims (15)

1. the array gamma irradiation quantimeter of FBAR structure on diaphragm, it is characterized in that: comprise detecting element, laminated film and Si pedestal, detecting element is positioned at above laminated film, laminated film is for supporting detecting element, and Si pedestal is positioned at below laminated film; Detecting element includes some rectangular array and is distributed in FBAR above laminated film, FBAR comprises hearth electrode, piezoelectric layer and top electrode from down to up successively, radiation sensitive layer is arranged between piezoelectric layer and hearth electrode or is arranged between piezoelectric layer and top electrode, and hearth electrode is close to laminated film upper surface; Si pedestal is provided with some cavitys, cavity and radiation sensitive layer position one_to_one corresponding in the vertical, and cavity is for the formation of bulk acoustic wave reflecting interface, and laminated film region corresponding above cavity is the unsettled region of laminated film; The quantity of described FBAR is N × M, N, M is positive integer.

2. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 1, is characterized in that: the FBAR of described detecting element is connected with pad by lead-in wire; Described lead-in wire comprises hearth electrode lead-in wire and goes between with top electrode, and pad comprises hearth electrode pad and top electrode pad, and the hearth electrode of FBAR is connected with hearth electrode pad by hearth electrode lead-in wire, and the top electrode of FBAR is connected with top electrode pad by top electrode lead-in wire.

3. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 2, it is characterized in that: FBAR, pad with the connected mode of lead-in wire are: the hearth electrode often arranging FBAR is all connected with same hearth electrode pad by same hearth electrode lead-in wire, often the top electrode of row FBAR all passes through same top electrode and goes between and be connected with same top electrode pad; Or often the hearth electrode of row FBAR all passes through same hearth electrode lead-in wire and is connected with same hearth electrode pad, and the top electrode often arranging FBAR is all gone between by same top electrode and is connected with same top electrode pad.

4. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 3, it is characterized in that: when radiation sensitive is placed between piezoelectric layer and hearth electrode, a part for piezoelectric layer bottom surface is close to radiation sensitive layer upper surface, another part of piezoelectric layer bottom surface is coated radiation sensitive layer side and hearth electrode side extend to the unsettled region upper surface of laminated film to both sides, a part for top electrode bottom surface is close to the upper surface of piezoelectric layer, and another part of top electrode bottom surface is coated piezoelectric layer side extend to the unsettled region upper surface of laminated film to both sides.

5. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 3, it is characterized in that: when radiation sensitive is placed between piezoelectric layer and top electrode, a part for piezoelectric layer bottom surface is close to hearth electrode upper surface, another part of piezoelectric layer bottom surface is coated hearth electrode side extend to the unsettled region upper surface of laminated film to both sides, a part for top electrode bottom surface is close to the upper surface of radiation sensitive layer, and another part of top electrode bottom surface is coated radiation sensitive layer side and piezoelectric layer side extend to the unsettled region upper surface of laminated film to both sides.

6. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 2, it is characterized in that: the connected mode of FBAR, pad and lead-in wire is: the hearth electrode often arranging FBAR is all connected in same hearth electrode bus by respective hearth electrode lead-in wire, and often the top electrode of row FBAR is all connected in same top electrode bus by respective top electrode lead-in wire; Or often the hearth electrode of row FBAR is all connected in same hearth electrode bus by respective hearth electrode lead-in wire, the top electrode often arranging FBAR is all connected in same top electrode bus by respective top electrode lead-in wire; Every bar hearth electrode bus connects a hearth electrode pad, and every bar top electrode bus connects a top electrode pad.

7. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 6, it is characterized in that: if radiation sensitive is placed between piezoelectric layer and hearth electrode, a part for piezoelectric layer bottom surface is close to radiation sensitive layer upper surface, another part of piezoelectric layer bottom surface is coated radiation sensitive layer side and hearth electrode side extend to the unsettled region upper surface of laminated film to side, a part for top electrode bottom surface is close to the upper surface of piezoelectric layer, and another part of top electrode bottom surface is coated piezoelectric layer side extend to the unsettled region upper surface of laminated film to both sides.

8. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 6, it is characterized in that: if radiation sensitive is placed between piezoelectric layer and top electrode, a part for piezoelectric layer bottom surface is close to hearth electrode upper surface, another part of piezoelectric layer bottom surface is coated hearth electrode side extend to the unsettled region upper surface of laminated film to side, a part for top electrode bottom surface is close to the upper surface of radiation sensitive layer, and another part of top electrode bottom surface is coated radiation sensitive layer side and piezoelectric layer side extend to the unsettled region upper surface of laminated film to both sides.

9. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 6, is characterized in that: at top electrode bus and hearth electrode bus infall, hearth electrode bus is covered with piezoelectric layer, and top electrode bus is passed through from the upper surface of piezoelectric layer; Piezoelectric layer in piezoelectric layer and FBAR is the same material with same thickness, is formed by same primary depositing and patterning process.

10. the array gamma irradiation quantimeter of FBAR structure on diaphragm according to claim 2, it is characterized in that: described hearth electrode, hearth electrode lead-in wire and hearth electrode pad are all the conductor materials of the same race with same thickness, formed by same primary depositing and patterning process; Top electrode, top lead-in wire and top electrode pad are all the conductor materials of the same race with same thickness, are formed by same primary depositing and patterning process; Described hearth electrode lead-in wire and top electrode lead-in wire are at laminated film region upper surface flexible route, and hearth electrode pad and top electrode pad are all arranged at the laminated film upper surface that Si pedestal correspondence supports.

The array gamma irradiation quantimeter of FBAR structure on 11. diaphragms according to claim 1, is characterized in that: described radiation sensitive layer adopts Si ₃n ₄or SiO ₂material, and use PECVD or LPCVD process layer to deposit.

The array gamma irradiation quantimeter of FBAR structure on 12. diaphragms according to claim 1, is characterized in that: described cavity is formed by deep reaction ion etching after the back-patterned formation etching window of silicon substrate.

On 13. diaphragms according to claim 1, the array gamma irradiation quantimeter of FBAR structure, is characterized in that: described laminated film is square diaphragm, and laminated film comprises SiO ₂layer and Si ₃n ₄layer, SiO ₂layer is connected with Si pedestal, Si ₃n ₄layer is positioned at SiO ₂above layer, the thickness of laminated film is SiO ₂layer and Si ₃n ₄the thickness sum of layer.

On 14. diaphragms according to claim 12, the array gamma irradiation quantimeter of FBAR structure, is characterized in that: the SiO in described laminated film ₂layer has positive temperature coefficient (PTC), is prepared by CVD technique; The piezoelectric layer of described FBAR has negative temperature coefficient; The SiO of laminated film ₂layer and the piezoelectric layer compound of FBAR, carry out temperature compensation, for improving the temperature stability of FBAR.

On 15. diaphragms according to claim 1, the array gamma irradiation quantimeter of FBAR structure, is characterized in that: described SiO ₂layer is as self-stopping technology layer during silicon substrate back-etching.