CN205792476U - A kind of FBAR using ultra-thin piezoelectric single crystal to make - Google Patents

Abstract

The utility model proposes a kind of FBAR using ultra-thin piezoelectric single crystal to make, including having the High resistivity substrate of room, ground, being clamped, by upper metal electrode and lower metal electrode, the sandwich active structure that piezoelectrics form, sandwich active structure is arranged at High resistivity substrate upper end；Described piezoelectrics are ultra-thin piezoelectric single crystal, and indoor, ground are provided with some pillars.Piezoelectric single crystal used by ultra-thin piezoelectric single crystal, for all piezoelectric single crystal that can be practical, such as quartz, lithium tantalate, Lithium metaniobate, lithium tetraborate, bismuth germanium oxide, bismuth silicate, gallium-lanthanum silicate serial, aluminum orthophoshpate and potassium niobate.High resistivity substrate used, commonly uses backing material for microelectric techniques such as silicon, quartz, carborundum, aluminium sesquioxide, sapphire, diamond.Advantage of the present utility model has: ultra-thin piezoelectric single crystal, and crystal perfection is not destroyed, for perfect monocrystalline；Can be with unrestricted choice crystal and crystal orientation thereof, optimized device performance；Ultra-thin piezoelectric single crystal production technology prospect is bright and clear.

Description

A kind of FBAR using ultra-thin piezoelectric single crystal to make

Technical field

This utility model relates to radio-frequency filter technical field, is specifically related to a kind of thin film using ultra-thin piezoelectric single crystal system to make Bulk acoustic wave resonator.

Background technology

Quartz crystal component, is a kind of bulk acoustic wave element based on quartz crystal piezoelectricity/inverse piezoelectric property, in channel frequency source It is used widely.Owing to the resonant frequency of quartz crystal component is inversely proportional to the thickness of quartz crystal, its resonant frequency is the most at present High only tens of megahertzs, it is impossible to meet the drastically extension demand of Modem radio frequency spectrum.

Use the planar metal interdigital transducer on piezoelectric substrate and metallic reflection grating array, excite and receive surface acoustic wave, will promote The structure of resonant frequency is improved transverse electrode resolution by thinning being converted to of thickness, by means of ripe microelectronic process engineering, makes The resonant frequency of surface acoustic wave quartz resonator rises to hundreds of megahertzs.

The application of the higher piezoelectric of conversion efficiency (such as Lithium metaniobate and lithium tantalate) substrate and the reality of surface acoustic wave resonance filter With novel, SAW resonator and surface acoustic wave resonance filter are rapidly developed, and operating frequency extends to again thousands of megahertzs Hereby, it has also become the standard frequency element of modern high frequency telecommunication circuit.

Equally, the operating frequency of SAW device was inversely proportional to the cycle of its interdigital transducer metal electrode, was limited to piezoelectric substrate Technique, the SAW device cost performance of Gigahertz level declines, it is impossible to catch up with the paces of modern communications frequency range high frequency.By This, film bulk acoustic wave device becomes various countries and makes great efforts the novel filtering components and parts of development.

FBAR (Film Bulk Acoustic Wave Resonator, FBAR) is to use piezoelectric membrane to replace The bulk acoustic wave resonator (quartz crystal oscillator) of natural single crystal piezoelectric substrate, its resonant cavity elementary structure (Fig. 1) is a grease piezoelectric Film-clamp sandwich structure between two metal electrodes, due to (inverse) piezoelectric effect of piezoelectric membrane, electric excitation produces to external world Resonance, its resonant frequency is mainly inversely proportional to piezoelectric membrane thickness, also relevant with other each layer characteristics of sandwich structure and thickness.

The most ripe FBAR device architecture is divided into barrier film (membrane) type and solid patch (Solidly Mounded) type two big Class.

Diaphragm type FBAR, as in figure 2 it is shown, be characterized in that the outer two sides of sandwich resonator cavity is all air, meets ideal total reflection State.Its structure can be divided into again: air bridges (Fig. 2 a), dorsal pore (Fig. 2 b) and three kinds of room, ground (Fig. 2 c).

Admittedly patch type FBAR, it is called for short again SMR (Solidly Mounded Resonator), as it is shown on figure 3, be characterized in Sanming City Controlling one side outside resonator cavity is air, and another side is Prague sound reflecting structure.Prague sound reflecting structure be by multiple high in a low voice Speed material (thickness is quarter-wave) layer combination is constituted, and its characteristic is similar to vacuum and entirely launches.Due to catoptric arrangement and pressure Conductive film grows simultaneously, and device technology is simple, and reliability is excellent, but owing to catoptric arrangement is lossy, its figure of merit is less better.

The most commercial grease piezoelectric's thin film used by FBAR, predominantly aluminium nitride (AlN) and zinc oxide (ZnO) is thin Film, all uses physically or chemically vapor phase deposition technique growth on patterned silicon substrate, and most widely used is magnetron sputtering work Skill.The piezoelectric membrane generated at present is monocrystalline or the strong-texture polycrystal film with certain orientation, still can not unrestricted choice piezoelectricity Optimized device performance is carried out in the crystal orientation of thin film.

In recent years, due to the propelling of wafer thinning techniques, large-size ultra-thin Lithium metaniobate (LiNbO3, LN), lithium tantalate The piezoelectric chip such as (LiTaO3, LT) and quartz batch is for high-frequency sound surface wave device.Obviously, LN/LT monocrystal Ultra thin wafer performance, more outstanding than the AlN/ZnO piezoelectric membrane that above-mentioned sputtering technology grows:

1. retain monocrystalline integrity；

2. crystalline anisotropy can make full use of；

3. single crystalline ultra thin chip technology is not difficult.

Applying for reality, single crystalline ultra thin sheet will become composite substrate with substrate bonding.At present, Lithium metaniobate, lithium tantalate superthin section can Forming technique mainly has two kinds in batches: crystal ionic section (crystal ion slicing, CIS) method and mechanical reduction side Method, all has started to be applied to element manufacturing.

Ion Sectioning, its principle is to utilize energetic ion vertical injection Lithium metaniobate, monocrystalline lithium tantalate thickness substrate, makes at monocrystalline thick Substrate interior away from the certain depth of surface formed one inject ion high concentration layer, certain physicochemical characteristic of the sub-high concentration layer of this leafing with Unimplanted place or concentration lower have more apparent difference (burying denatured layer also known as interior).After early stage technique completes, use one This thick wafer is processed by stress, makes thick wafer rupture at high concentration layer, it is thus achieved that ultra thin wafer.The thickness of ultra thin wafer is by injecting The ion high concentration layer degree of depth determines, it is relevant with the injection technological parameter such as ionic species, implantation dosage, annealing etc..

The manufacturing process of ion Sectioning such as Fig. 4, initially with heavy dose of ion implantation apparatus, to thicker piezoelectric monocrystal sheet front Inject ion, make to be formed a high concentration ion layer at a certain distance from sheet lower face.By substrate polished surface and piezoelectricity list Wafer face opposite is bonded, and forms composite substrate.After early stage technique completes, use a kind of stress that this composite substrate is processed, make Composite substrate ruptures at high concentration layer, it is thus achieved that the ultra-thin piezoelectric chip being attached on substrate.

The feature of Sectioning is: be prone to the special ultra thin wafer making tens nanometer to a few micrometers thickness, but crystal is tied by ion implanting The damage of structure integrity is big, and single crystal characteristics can have a significant effect.

Mechanical reduction method, is the improvement of conventional art, and Fig. 5 illustrates its main processes: first make original piezoelectric monocrystal Sheet and the composite substrate of substrate, then face down piezoelectric monocrystal sheet, and attenuated polishing is until piezoelectric monocrystal sheet thickness meets design and wants Till asking.Its key technology is substrate, original piezoelectric monocrystal sheet and the large scale uniformity of bonded layer and process equipment.Due to Mechanical lapping and polissoir and the progress of technology, make the large-size ultra-thin monocrystal chip problem of less than ten microns thickness not at present Greatly, its feature is just contrary with ion Sectioning: be prone to make the ultra thin single crystalline sheet of the above thickness of a few micrometers, and will not be to list Jingjing bulk properties causes substantially damage.

Utility model content

Use existing ultra thin single crystalline sheet forming technique, in conjunction with existing FBAR production technology, propose one and use ultra-thin piezoelectricity list The technology of Thin Film Bulk Acoustic Wave Resonator scheme that crystal makes, principle is illustrated such as Fig. 6.

The utility model proposes a kind of FBAR using ultra-thin piezoelectric single crystal to make, belong to ground cell structure barrier film Type FBAR,

The sandwich mainly include the High resistivity substrate with room, ground, being made up of upper metal electrode and lower metal electrode clamping piezoelectrics has Source structure, sandwich active structure is arranged at High resistivity substrate upper end；Described piezoelectrics are ultra-thin piezoelectric single crystal, set in indoor, ground There are some pillars.

In FBAR of the present utility model, the piezoelectric single crystal used by ultra-thin piezoelectric single crystal, for all can be practical Change piezoelectric single crystal, as quartz, lithium tantalate, Lithium metaniobate, lithium tetraborate, bismuth germanium oxide, bismuth silicate, gallium-lanthanum silicate serial, Aluminum orthophoshpate and potassium niobate etc..

In FBAR of the present utility model, High resistivity substrate used, for silicon, quartz, carborundum, three oxidations two The microelectric techniques such as aluminum, sapphire, diamond commonly use backing material.

Compared with prior art, advantage of the present utility model has:

The most ultra-thin piezoelectric single crystal, crystal perfection is not destroyed, for perfect monocrystalline；

2. can be with unrestricted choice crystal and crystal orientation thereof, optimized device performance；

The most ultra-thin piezoelectric single crystal production technology prospect is bright and clear.

For simply, device of the present utility model is called CFBAR (wherein CF represents monocrystalline thin slice) later.

Accompanying drawing explanation

Fig. 1 FBAR principle: sandwich resonator cavity.

Fig. 2 diaphragm type FBAR.

Fig. 3 patch type FBAR admittedly.

Fig. 4 ion Sectioning manufacturing process.

Fig. 5 mechanical thinning process flow process.

Fig. 6 this utility model: use the FBAR (CFBAR) that ultra-thin piezoelectric single crystal makes.

The structural representation of Fig. 7 CFBAR embodiment one.

Fig. 8 CFBAR embodiment one technological process 1 HR-Si substrate: clean, room, photoetching ground figure.

Fig. 9 CFBAR embodiment one technological process 2 HR-Si substrate: corrosion silicon, forms room, crutched ground.

Figure 10 CFBAR embodiment one technological process 3 HR-Si substrate: deposit bonded layer (SiO2).

The original piezoelectric monocrystal sheet of Figure 11 CFBAR embodiment one technological process 4: clean, makes bottom electrode.

The original piezoelectric monocrystal sheet of Figure 12 CFBAR embodiment one technological process 5: make passivation layer, and planar surface.

The original piezoelectric monocrystal sheet of Figure 13 CFBAR embodiment one technological process 6 is bonded face-to-face with HR-Si substrate, is formed compound Substrate.

Figure 14 CFBAR embodiment one technological process 7 uses mechanical reduction method to obtain piezoelectric single crystal superthin layer structure.

Figure 15 CFBAR embodiment one technological process 8 photoetching corrosion is formed with source region, and bottom electrode extraction electrode.

Figure 16 CFBAR embodiment one technological process 9 makes upper electrode and extraction electrode thereof.

Figure 17 CFBAR embodiment two technological process 4a original piezoelectric monocrystal sheet: clean, ion implanting.

Figure 18 CFBAR embodiment two technological process 4a original piezoelectric monocrystal sheet: make bottom electrode.

Figure 19 CFBAR embodiment two technological process 7 uses CIS method to obtain piezoelectric single crystal superthin layer structure.

Accompanying drawing marks: upper electrode 1, piezoelectric membrane 2, bottom electrode 3, HR-Si substrate 4, room, ground 5, pillar 6, air 7, the back of the body Facet etch 8, reflector storehouse 9.

Detailed description of the invention

The following detailed description of detailed description of the invention of the present utility model.

Using CFBAR embodiment one of the present utility model, CFBAR device architecture is illustrated in Fig. 7, is current current techique Ground cell structure diaphragm type FBAR.

Device uses High Resistivity Si as substrate.Piezoelectric monocrystal used by device, uses requirement, generally Lithium metaniobate, tantalum according to device The acid common used material such as lithium or quartz, because the batch production of these piezoelectric monocrystals, cost performance is good.Electrode metal typically uses molybdenum, gold Deng weight density metal.

The manufacturing process of embodiment one such as Fig. 8～Figure 16 shows, belongs to Conventional microelectronic Technology.This utility model have employed two The wafer of individual same size single-sided polishing: HR-Si substrate and piezoelectric single crystal, and burnishing surface is called front.

Fig. 8 is CFBAR embodiment one technological process 1: clean HR-Si substrate, room, front photoetching ground figure.This practicality Novel employing has pillar ground cell structure, and this technical scheme describes in detail in the utility model patent of our earlier application.

Fig. 9 is CFBAR embodiment one technological process 2: HR-Si substrate uses standard technology corrosion silicon, is formed with pillar Room, ground.

Figure 10 is CFBAR embodiment one technological process 3: have figure front to deposit a bonded layer at HR-Si substrate, generally SiO2 deielectric-coating, for being bonded HR-Si substrate with original piezoelectric monocrystal sheet.

Figure 11 is CFBAR embodiment one technological process 4: after cleaning original piezoelectric monocrystal sheet, front deposit metal film, light Carve corrosion and make bottom electrode.

Figure 12 is CFBAR embodiment one technological process 5: deposit passivation layer in original piezoelectric monocrystal sheet front, generally SiO2 deielectric-coating.Passivation layer thickness is more than existing thickness of electrode, therefore needs to use chemical mechanical method planar surface, makes dew The electrode surface gone out is smooth as passivation layer surface.

Figure 13 is CFBAR embodiment one technological process 6: by original piezoelectric monocrystal sheet with HR-Si substrate front to front key Close, form composite substrate.Bonding technology is known standard micro technique, and its bonding parameter should carefully adjust, adapt to piezoelectricity The stress sensitive characteristic of monocrystal, as reduced thermograde, reducing piezoelectric effect and pyroelectric effect impact etc..

Figure 14 is CFBAR embodiment one technological process 7: use aforesaid mechanical reduction method, uses high-accuracy grinding to cast standby Piezoelectric single crystal superthin layer structure is obtained, till the thickness of piezoelectric single crystal superthin layer should meet design requirement with technology.Based on silicon Sheet thickness, bonded layer one-tenth-value thickness 1/10, the thickness of inspection piezoelectric single crystal superthin layer and the uniformity thereof.

Figure 15 is CFBAR embodiment one technological process 8: alignment corrosion is formed with region meas, alignment deposit stripping technology system Make bottom electrode and extraction electrode.

Figure 16 is CFBAR embodiment one technological process 9: alignment deposit stripping technology makes upper electrode and extraction electrode thereof.

Above-mentioned employing CFBAR of the present utility model embodiment one, the moulding process of piezoelectric single crystal superthin layer have employed machinery and subtracts Thin method.Following employing CFBAR of the present utility model embodiment two, institute's citing device architecture is fully equivalent to embodiment one (Fig. 7), simply the moulding process of piezoelectric single crystal superthin layer uses crystal ionic section (CIS) method.

Realize the manufacturing process of embodiment two device, embodiment one essentially identical, only it is intended to revise operation 4 and operation 7, its Remaining general, certainly in corresponding process chart, stand the original piezoelectric monocrystal sheet after ion implanting, denatured layer can be buried in marking. Below the operation that need to revise is described in detail.

Figure 17 is CFBAR embodiment two technological process 4a: after cleaning original piezoelectric monocrystal sheet, disk front carries out ion Injection technology, buries denatured layer in formation.

Figure 18 is CFBAR embodiment two technological process 4b: deposit metal film, photoetching corrosion in original piezoelectric monocrystal sheet front Make bottom electrode.

Figure 19 is CFBAR embodiment two technological process 7: use aforesaid ion dicing method, uses physics (hot) or changes Learning stress makes composite substrate rupture at denatured layer interior burying, it is thus achieved that piezoelectric single crystal superthin layer, the thickness of piezoelectric single crystal superthin layer Meet design requirement.

Although this utility model is described by embodiment, but embodiment is not used for limiting this utility model.This area skill Art personnel can make various deformation and improvement in the scope of spirit of the present utility model, but same all guarantor of the present utility model Within the scope of protecting.Protection domain the most of the present utility model should be with being as the criterion that claims hereof protection domain is defined.

Claims (3)

1. one kind uses the FBAR that ultra-thin piezoelectric single crystal makes, it is characterised in that include having room, ground High resistivity substrate, the sandwich active structure being made up of upper metal electrode and lower metal electrode clamping piezoelectrics, sandwich active structure It is arranged at High resistivity substrate upper end；Described piezoelectrics are piezoelectric single crystal superthin layer, are provided with some pillars in indoor, ground.

2. according to a kind of FBAR using ultra-thin piezoelectric single crystal to make described in claim 1, its feature Being, piezoelectric single crystal is to use quartz, lithium tantalate, Lithium metaniobate, lithium tetraborate, bismuth germanium oxide, bismuth silicate, gallium silicate group of the lanthanides Row, aluminum orthophoshpate or potassium niobate piezoelectric single crystal.

3. according to a kind of FBAR using ultra-thin piezoelectric single crystal to make described in claim 1, its feature It is, it is characterised in that High resistivity substrate is by silicon, quartz, carborundum, aluminium sesquioxide, sapphire or diamond Make.