CN1021389C - Structures and processes for fabricating field emission cathodes - Google Patents

Abstract

The present invention relates generally to new structures for a field emission cathode and processes for fabricating the same. The field emission is made of any material that is capable of emitting electrons under the influence of an electrical potential. The field emission cathode has several unique three dimensional structures. The basic structure comprises of a layer of material with cathode tips. For a more complex structure the cathode tip is preferably accurately aligned inside an extraction/control electrode structure, in preferably a vacuum environment. The structures of this invention can be fabricated to be connected to other similar field emission cathodes or to other electronic devices.

Description

Structures and processes for fabricating field emission cathodes

The present invention relates generally to the structure and the manufacture method thereof of field emissive cathode single or array.This field emissive cathode single or array can have or not have integrated extraction electrode and/or control electrode.More particularly, the present invention relates to the structure of field emissive cathode and make the process of this structure.

Present patent application relates to the U.S. Patent application series NO.07/555 that submits July 18 nineteen ninety simultaneously, and No. 214 (IBM Attorney Docket NO.FI9-90-018), therefore, this paper will be with reference in conjunction with its disclosed content.

Electron source or negative electrode have requisite function concerning various electronic devices.Usually, vacuum device, for example the negative electrode of vacuum tube and cathode ray tube just utilizes thermionic emission to produce required electronics.This just requires direct conduction current or makes cathode material be elevated to very high-temperature by means of auxiliary heater, and this method needs sizable electric current, and as used heat.Consume many energy, efficient is very low.

In recent years, increased the interest that replaces the thermionic cathode of poor efficiency with high field emissive cathode.Eliminated necessity of heated cathode material because of field emissive cathode, this cathode efficiency is very high.Electron source as scanning electron microscopy used quite a lot of years, and the now is just testing as vacuum microelectronic device, flat-panel monitor, and the electron source of high-performance high-frequency vacuum tube.

Field emissive cathode comprises the very sharp-pointed tip (typical radius is less than 100nm) of field emission material.When adding negative potential, electric field can be gathered in the end in this tip.High electric field like this can make electronics " tunnelling " top enter the space that keeps high vacuum state on every side usually.The required current potential size of electric field of generation sufficient intensity is proportional to the distance between most advanced and sophisticated and main extraction electrode.This main extraction electrode will be referred to as extraction pole.As long as this extraction pole can be a branch main structure physically, just can reach minimum extraction potential easily by the utmost point with extraction pole by physically direct integrated field emissive cathode is most advanced and sophisticated.This just produces the very little extraction pole-cathode distance of suitable secured in alignment physically.The field emission cathode construction that no matter is with or without integrated extraction pole all is useful electron source as display, vacuum microelectronic device and various electron microscope under all electric currents and current potential application.

Utilize the field emission display element of these negative electrodes to adopt basic field emission structure and add auxiliary structure, such as, the extension of a vacuum space, with the opposed fluorescence surface layer of cathode point and collect and/or the auxiliary electrode of control electron stream.When make forming integrated circuit and/or display, be the in addition interconnection of electricity of the upright vacuum microelectronic device of a component and/or display element.

As long as these field emission cathode constructions can be made into almost arbitrarily size and can be used as the separate electronic source, so, the place of wishing of their optimum performance and main application will be from maximum microminiaturization, and intensive array.

The field launcher of non-thermion, field emission device and field-emitter display are well-known in the prior art.Making field emission cathode construction is a kind of common key element of above-mentioned device.Adopt quite common deposit and the lithography process technology all can deposit and processing various materials (insulator and conductor/field emitter), only except the structure of general a kind of sharp-pointed especially cutting edge (blade) of all field emissive cathodes or tip (tip).

The prior art of making sharp-pointed field emission tip or blade can be divided into five types usually.The method that forms extraction pole also has suggested in the example of these types.

First type is one of type of earliest period, and wherein the cathode point structure is through directly deposition materials formation.The example of lifting a this pattern is one piece of paper of C.A.Spindt: " a kind of thin film field-emission cathode " (J.Apple.Phys., Vol.39, NO.7, pp3504-3505,1968), wherein sharp-pointed taper molybdenum emitter is formed in the hole of a molybdenum anode layer and on a molybdenum cathode layer.Separate with insulating barrier that this is two-layer, this insulating barrier in the porose area of anode layer etching remove until cathode layer portion.Molybdenum of deposit respectively and aluminium oxide by normal and steep angle forms cone on the substrate that is rotating that includes anode and cathode layer simultaneously, removes the aluminium oxide of deposit again selectively.Similarly work is also at United States Patent (USP) 3,755, done open No. 704.

Second type is to utilize etching and the relevant etching of monocrystal material (for example silicon) orientation.Be preferentially to corrode an a kind of particular crystal plane of material with the relevant etched principle of orientation.Utilization has the monocrystal material of masking material pattern, and the anisotropic etching zone will be by the constraint of slow etching face, and this slow etching face meet is at the limit that the basic crystalline form of material is determined and the recess of point.The tip that suitably cooperates etching, material and orientation just can produce the very sharp-pointed regulation that can be used as field emitter.The United States Patent (USP) of issuing Spindt etc. is exactly for No. 3665241 an example of this method, one of them above island etching mask is arranged on the monocrystal material, corroded with a kind of etchant then, some crystrallographic plane of etchant etch material is faster than other planes, because the bounded etch profile that slow etching plane (a kind of etching relevant with orientation) causes.If shrink under the mask center on slow etching plane, that will form has sharp-pointed knife-edge and most advanced and sophisticated a plurality of faceted geometric shape, and its shape depends on etchant, crystal orientation, and the shape of mask.In case determined to bring up most advanced and sophisticated method, the anisotropic etching relevant with orientation also has deleterious effects, and tip that these are sharp-pointed is made and justified blunt the radius of cathode point (or reduce), thereby reduction is as the effectiveness of field emitter, as Cade, N.A. etc., " wet etching that is used for the pinnacle structure of field emission device ", IEEE Trans, onElectron Devices, Vol.36, No.11, pp2709-2714(1989 November), discussed like that.

The third type adopts the isotropic etching method to form structure.Isotropic etching is exactly all to be subjected to corrode equably in all directions.When sheltering, the edge of this mask becomes the central point of one section arc, depicts the profile of typical isotropic etching under mask material.The radius of this circular arc equals etched depth.Corrode around isolated island of sheltering, etched section is shunk to the mask center at the tip that remains the uncorroded material that can be used as field emitter.This is to be presented to an embodiment who enumerates in No. 3,998,678, the United States Patent (USP) of Shigeo Fukase etc.Usually, shelter emitter material with the island of photoetching formation and erosion-resisting material.Corrode this emitter material with the isotropic etchant that forms isotropic etching section (circular vertically have a section that under photoresist, stretches to the radius at edge).When the etching section from each limit when shrink at the mask center, the result is a cusp or small end.Operation subsequently is added to extraction pole on the structure sometimes.

The 4th type is utilized oxidation technology, tapers off to a point by the oxidation of emitter material.In fact the section with isotropic etching under mask is the same for the section of oxidation under oxidation mask, and forms same cutting-edge structure, just like the section contraction converges under a kind of circular masks.When removing oxidized material, just can gather in threshed grain on a threshing ground and cause the effect of emitter in not oxidated tip.Authorize United States Patent (USP)s such as Smith and just enumerate this process 3,970, No. 887.The technology of the type is very similar to the isotropic etching type.The substrate of electronic emission material is for example used silicon.The oxide layer growth of heat growth is that lithographic printing becomes drawing and etches one or more titanium dioxide silicon island on substrate then.Subsequently, substrate is reoxidized, at this moment, these islands that before formed oxide just have significantly slows down its oxidation of silicon down.Resulting oxide section is very similar to the section of isotropic etching, and similarly shrinks under the island, can expose silicon and stays sharp-pointed summit section through removing oxide.In this example, will after having formed the tip, add extraction pole on structure.Other masking materials, for example silicon nitride also can be used for slowing down oxidation equally and make desired most advanced and sophisticated section.

The 5th type is corrosion one pit, erodes away the hole opposite with required pointed shape and then remove by corrosion as a mould of emitter material in consumptive material.The United States Patent (USP) of authorizing Gray etc. is enumerated the special case of a this technology for 4,307, No. 507.Hole in the masking material is formed on the monocrystalline silicon substrate by photoetching.This substrate is done and the relevant etching of orientation by mask hole, forms the etch pit opposite with required pointed shape.Remove mask and fill up this pit at whole surface deposition one deck emissive material.Silicon mould is removed in corrosion then, isolates the most advanced and sophisticated duplicate of pit, can be used as field emitter.This piece patent does not disclose and adopts a kind of integrated extraction pole.

Above-mentioned all emitters form technology all some limitation.The relevant etching of orientation need be used a kind of substrate of monocrystalline emissive material.They mostly need emissive material to make or coated substrates.They mostly at first form emitter, the manufacturing process of complicated follow-up electrode layer.

Sometimes, these methods of employing or the special-purpose processing specification field emission tip of also can not produce enough minor radius.Prior art comprises the method that some can further reduce the tip its radius, come to a point.One piece of paper of Campisi etc.: " adopting the etching method little processing relevant to be used for the field emission device of vacuum integrated circuit " with orientation, Mat.Res.Soc.Symp.Proc., Vol.76, pp67～72(1987), reported under isotropic etch to make it to become sharp through corroding the silicon tip end slowly.Another piece of writing is entitled as: " Livermore small size vacuum pipe problem progress report ", W.J.Orvis etc., IEDM89 pp529-531(1988), has reported by thermal oxidation silicon tip post-etching and has peeled off this oxide and make it the method that becomes sharp.A kind of circular cone or the multi-stylus head at pyramid field emitter tip or new method of microcephaly of providing also is provided for 3.921, No. 022 United States Patent (USP).As Busta, H.H. wait in " field emission of tungsten cladding silicon pyramid ", IEEE Trans.on Electron Devices, Vol.36, No.11, pp2679-2685(1989 November), the illustrating an of literary composition can adopt on these cathode points or pyramid coating or cladding thing to strengthen or improve the performance of cathode point now.

In this development field, prior art has also been displayed end for the first time and has been looked askance, in practical application, as how to use these field emissive cathodes and extraction pole in display application.The United States Patent (USP) of authorizing Spindt etc. has illustrated for 4,857, No. 799, and the substrate that how will include field emitter and extraction pole is attached on the discrete transparent window that plate conductor and phosphor strip are arranged, and all these synergies have formed color monitor.The another kind of chromatic display that uses microelectronic vacuum type structure is No. 3,855,499, a United States Patent (USP) obtaining patent.

Generally speaking, a kind of typical field emission cathode construction is to be made of a termination sharp keen tip or blade.This cathode point or blade also can wind with the control utmost point and/or an extraction pole.One of key technology of making this class device is to make sharp-pointed field emission (negative electrode) tip that radius is preferably the 10-100nm magnitude.The most public most advanced and sophisticated method of making comprises etching method, the isotropic etching method relevant with orientation, and thermal oxidation method.

On the one hand, the present invention includes a kind of process that at least one field emissive cathode is made, comprise these steps;

A) hole is set at least on the substrate;

B) deposit one first material at least, and fill this hole some at least, make it to be enough to form a tip;

C) material layer that deposit one deck can emitting electrons under electric field influence at least, and fill the tip portion of tip at least, and

D) remove first material under the tip, expose the tip portion of electronic emission material at least, so form at least one field emission cathode construction.

On the other hand, the present invention's a kind of process of making at least one field emission cathode construction comprises step:

A) form the layer of conductive material layer at least in a basic unit;

B) form a hole at least, pass one deck conductive layer at least at least;

C) a kind of insulating material of deposit is on one deck conductive layer at least at least, an and part of filling up this hole at least makes it to be enough to form a tip;

D) material layer that deposit one deck can emitting electrons under electric field influence at least, it covers on the said insulating material of step c), and fills the tip portion of this tip at least, and

E) remove material under the tip, expose the part of electronic emission material at least, so, at least one field emission cathode construction formed.

A kind of process that the present invention makes at least one field emission cathode construction also comprises step:

A) form a plurality of conductive material layers on a basic unit, and each conductive material layer is isolated with insulation material layer;

B) form a hole at least, pass these conductive layers at least;

C) deposit one insulating cove is on these conductive material layers at least, and the part of filler opening at least makes it to be enough to form a tip;

D) material layer that deposit one deck can emitting electrons under electric field influence at least, it covers on the insulating material of step c), and fills the tip portion of this tip at least, and

E) remove material under the tip, expose the part of emitting electrons at least, so, at least one field emission cathode structure formed.

Another aspect of the present invention is made up of a kind of field emission cathode construction, comprises the material layer that one deck can emitting electrons under electric field influence, and has a tip that is used for emitting electrons that forms by method of the present invention at least.

Field emission cathode construction of the present invention also comprises, has a conductive material layer at least at this tip side of electron emission layer, and it separates with an insulation material layer at least, so that expose this emitter tip.

Field emission cathode construction of the present invention further comprises, at this tip side of electron emission layer a plurality of conductive material layers arranged, and each all uses at least a insulating material to separate each other and with electron emission layer, so that the emitter tip is exposed.

Field emission cathode construction of the present invention can comprise in addition, has a barrier at least at the most advanced and sophisticated side of electron emission layer, and it can be removed selectively, is used for exposing this tip.

Any method of the present invention can both be made a kind of product.

One object of the present invention is to form field emission single or array tip.

Another object of the present invention is to eliminate the few dependence to monocrystal material, and can keep high degree of flexibility that field emission material is selected for use.

Another purpose is to make a kind of integrated extraction electrode, not only autoregistration but also be to constitute the part that forms technology as most advanced and sophisticated, and needn't add follow-up operation, so just simplified total process for making greatly.

Also have a purpose, adopt public microminiature ic manufacturing technology to go to cause these structures.

These purposes of the present invention reach like this, adopt the deposit or the formation technology of conforma layer, fill the sort of tip that on-chip hole forms use.This tip is as a kind of mould, filling it at any material (emission layer) of emitting electrons under the electric field influence.After this mould was by some public relieving mechanisms or the cambium layer by selective corrosion substrate and tip, a kind of sharp tip of duplicate of this tip was just exposed.

This most advanced and sophisticated radius of wishing that formation is enough little is so that play field emissive cathode.For various reasons, need a kind of tip of point, can use processing method well known in the prior art that the tip is come to a point, for example most advanced and sophisticated etching method of isotropism at a slow speed, or oxidation is also removed conventional ceramic technique.

This method is not limited to use some specific materials.The composition of many materials and material all can be used as substrate, conforma layer and emitter material.

By earlier the electrode layer of conduction being deposited on the substrate of supporting, extraction pole can be appended on the basic structure.Be used as that hole that forms tip subsequently, etching pass this conductive electrode layer also to or enter in the substrate.Deposit or then form the cambium layer of conformal tip by the deposit emitter layer.Separate or etch away substrate selectively with corrosive agent that can not the etch conductive electrode.Then, with neither can etch conductive electrode (extraction pole) also the corrosive agent of not etch emitter material remove conforma layer selectively, up to the tip being exposed to desired degree.

When this structure is placed in, for example in the vacuum, and add a sufficiently high current potential, cross-over connection is in very just drawing, and field emission is most advanced and sophisticated when negative, consequent high electric field can make the electron tunneling tip enter the zone, vacuum space on the tip.

Such process is also permitted additional more electrode, resembles can be used to draw, control in the such structure of array or choose specific projectile configuration.These additional electrodes should begin from the electrode of topped substrate to increase.Deposit one layer insulating is followed deposit one additional electrode layer again.The so a pair of new layer of every repetition deposit just produces an additional electrode.After a while will be in order to forming the hole of tip, present then want etching penetrate all electrodes and insulating barrier until or enter basic unit itself.And after this, technology is proceeded down as finishing single extraction pole structure.

Multiple electrode structure has showed that insulant between electrode is subjected to the possibility of nonproductive sapping.If use isotropic etching to come the formation material and the electrode insulation thing of the conformal tip of etch, this sapping will occur.Adopt the just obvious material or the emitter layer of that first electrode of close substrate of etch not of anisotropic etching.

Release or barrier can be used in each step of technical process, can easily separate with the structure of finishing that finish or local to guarantee mould or substrate, perhaps as etch stop layer, perhaps as protective layer, came the assist control technical process.For instance, if there is the people to wish to use the tip that forms in conformal deposition silicon to make a silicon emitter tip, so, silicon-silicon interface is removed tip and the tip is exposed with regard to not allowing such selectivity.This obstacle can be by adding the very thin silicon nitride film layer of one deck to this tip layer, then silicon deposit is filled on the tip and is eliminated.Now, since silicon nitride stop that this additional layer will be permitted tip silicon is done etching.Subsequently, the available silicon that can etch remain, the etchant at the tip of just exposing is removed silicon nitride as the phosphoric acid of boiling.

Each electrode layer comprises that emitter layer generally uses good conductor, and therefore, and under accession one deck can be photo-etched into pattern with it before going to form interconnection between insulation and the projectile configuration.Equally, but the insulating barrier that adjoins also photoetching form through hole and be used for perpendicular interconnection.A kind of use of this photoengraving pattern is to form X and Y address line, can be used in the display application select startup single or one group of emitter.

Also can understand theme of the present invention better in conjunction with the accompanying drawings with reference to following detailed description, more advantage and feature can become clearer and more definite.

These features of the present invention believe it is new, and element characteristic of the present invention is at length showed in each additional claim.These accompanying drawings purpose as graphic extension, and do not draw by size.The present invention itself, the structure aspect still is that operational method all can and be understood in conjunction with the accompanying drawings better with reference to following detailed description.Wherein:

Figure 1A is the sectional view of a single substrate, has at least a hole to be used to form the emitter tip subsequently.

Figure 1B is the sectional view of on-chip deposit one a tip cambium layer of expression and an emitter layer.

Fig. 1 C represents the sectional view of the emitter layer of the vacant state after has exposed at the emitter tip.

Fig. 1 D represents that this emitter tip has been capped and this emitter layer is provided with the sectional view of the emitter layer of a vacant state after the supporting course.

Fig. 2 A is that the expression substrate is included in the sectional view that an exhaustion layer is arranged under the electrode layer and have an alternative embodiment of the invention in a hole at least.

Fig. 2 B is the sectional view after presentation graphs 2A structure has covered tip cambium layer and emissive material layer.

Fig. 2 C is the sectional view after presentation graphs 2B structure has been removed exhaustion layer.

Fig. 2 D after remove the tip cambium layer part in the integrated extraction pole, exposes the sectional view at emitter tip.

Fig. 3 A represents the sectional view of another embodiment of the present invention, shown in substrate comprise the two-layer electrode layer that separates by a insulating barrier in basic unit, and have a hole at least.

Fig. 3 B is the sectional view of presentation graphs 3A structure after has exposed at the emitter tip.

Fig. 4 A is that expression the present invention also has the sectional view of another embodiment, and this emitter layer has a barrier and a plurality of electrode one to reinstate insulating material to separate here.

The sectional view that this barrier material exists and exposed around the most advanced and sophisticated place of emitter in Fig. 4 B presentation graphs 4A structure.

Barrier material exists and around the sectional view that barrier material has been removed and has exposed at the emitter tip at the most advanced and sophisticated place of emitter in Fig. 4 C presentation graphs 4B structure.

Fig. 5 A is the sectional view of the resulting tip in hole that do not become with the degree of depth of conformal filling one size of expression.

Fig. 5 B represents to make of another method the sectional view of tip, and fenestra has the section that does not wait, and therefore, can adjust the position of tip.

Fig. 5 C represents the sectional view of another making tip method, and fenestra also has the section that does not wait.

Fig. 6 is illustrated in the hole that a size does not become with the degree of depth, makes the sectional view of tip to a certain extent by conformal process.

Explain through diagrams a kind of sectional view of field emissive cathode of Fig. 7 A, 7B and 7C, this negative electrode have come to a point blunt nosed.

Fig. 8 graphic table illustrates the perspective and the partial sectional view of a kind of field emissive cathode of interconnection.

The invention describes and be used for integrated manufacturing field emissive cathode, and field emissive cathode can have the innovative techniques and the structure of the necessary single or multiple extraction poles and/or the control utmost point.These structures all can be made single or in groups.

The explanation that utilizes several methods of being scheduled to and hereinafter naming or mention repeatedly describes the structure and the manufacture method thereof of these field emissive cathodes in detail.

Field emissive cathode of the present invention can be used as the electron source of vacuum microelectronic device.Term VMD or be called vacuum microelectronic device does not here only mean a kind of diode, and is meant triode, tetrode, pentode or any other device of making in this way, comprises in they be interconnected in.In essence, VMD has at least one sharp-pointed emitter (negative electrode) tip, and a collector electrode (anode), with insulant emitter and anode are separated, and preferably electronics from the emitter straight line or directly be sent to collector electrode (anode).

Term " photoetching limits " is meant a series of processing procedures of following processing step.At first will be to some actinic radiation mode, for example the masking layer of light, electron beam and/or X-ray positivity or negativity sensitivity is deposited on the surface of being considered.Secondly,, be exposed under the suitable actinic radiation this layer and development, optionally remove masking layer and the surface of exposing under the required pattern in the mode of pattern imitates.The 3rd, if necessary, all or part of of its beneath material removed on the surface that etching is exposed.The 4th, remove the reserved area of masking layer.

In other words, term " photoetching limits " also can be censured and is following " stripping technology ".Form identical desired pattern on the material layer that the technology of being narrated by the front is made.This technology is conceived to obtain to have carved the surface of the material layer of pattern.At first, will be to some actinic radiation, as the masking layer deposit of the positivity of light, electron beam and/or X-ray or negativity sensitivity from the teeth outwards.Secondly,, make exposure and the development under suitable actinic radiation of this layer, remove masking layer selectively and make it to expose surface under pattern, stay desired material layer in the pattern imitates mode.The process of deposit, exposure and development is control like this, makes the edge of the mask image that stays have a Butut opposite or that sink.The 3rd, by a series of depositing technics of being of seeing, as evaporation, desired material in the deposit all in window and the whole zone that is covered with mask.At last, remove mask material, for example by decompose and separate cover on it any material and make it to be rinsed.

Term " electric conducting material " or " conductor layer " or " conductive substrate " are meant the conductor material of the electricity that any kind of is various.Typical example comprises: element M O, W, Ta, Re, Pt, Au, Ag, Al, Cu, Nb, Ni, Cr, Ti, Zr and Hf, the alloy or the solid solution that contain two kinds or more kinds of these elements, semiconductor such as Si, the Ge of doping or non-doping, the compound of III-V that those are known, and non-semiconducting compound such as various nitride, boride, hexahedron compound (LaB for example ₆) and some oxide (as Sn, Ag, InSn).

Term " material of insulation " or " insulator layer " or " insulating substrate " mean the insulating material, particularly glass and pottery of various electricity.Typical example comprises: element such as diamond-type (crystallization or amorphous) carbon, the fluoride of the oxide of single crystal compound such as sapphire, glass and polycrystalline or amorphous compound such as some Si, Al, Mg and Ce, number of C a or Mg, the carbide of some silicon or nitride, and pottery is as alum clay or glass ceramics.

Term: electronic emission material " or " emitter layer " or " emitter material " mean under electric field action any material that can emitting electrons.Typical example comprises; The conductor of any electricity is enumerated such as above-mentioned, and the boride of rare earth element, comprises 1) boride and 2 of a kind of rare earth or a kind of alkaline earth (as Ca, Sr or Ba) element) solid solution of boride of a kind of transition metal (as Hf or Zr) element.This emitter material can be an individual layer, combination or sandwich construction.As an example, the multilayer emitter can contain the material layer below additional one or more layers: work function enhancement layer, durable emission layer, high-performance electrically-conductive layer, thermal conductance layer, physically strengthening layer or reinforced layer.This multi-layered composition can include emission and material non-emission, all collaboratively can optimize emission function together.Busta, H.H etc.: " field emission of the silicon taperer of tungsten clad ", IEEE Trans.on Electron Drvices, Vol.36, No.11, pp2679-2685(1989 November), this article was discussed this example, in this article, their proof adopts on these cathode points or taperer and applies or the clad layer, can strengthen or improve the performance of cathode point.

The occasion that this coat or clad layer also can be used for forming desired cathode emitter cutting-edge structure or be difficult to form desired cathode emitter cutting-edge structure.

Term " deposit " refers to any method that material forms rete that is suitable for, and generally is applied to whole semi-conductor industry.Some deposition technology of enumerating below all can be used for the material that the front was said, for example, and sputter, chemical vapor deposition, plating or electroless plating, oxidation, evaporation, desublimation, plasma deposition, anodic oxidation, anode deposit, molecular beam deposition or light deposit.

Term " tip " as used here, not only refers to the projection of fining away also be meant blade.The field emission shape that is not needle-like will be used sometimes, for example blade.Except that long and narrow fragment is made in the hole into, also adopt the formation cutting edge that uses the same method.It can be rectilinear or circular or straightway or curved section that the shape of blade sharp-edged is lifted several examples.

The Kongzui of making field emission cathode construction of the present invention is selected from one group of technology that comprises grinding, boring, etching, ion beam milling or compacting well and forms.Utilization is selected from one group of etching technique that comprises anisotropic etching, ion beam milling, isotropic etching, reactive ion etching, plasma etching or apparent method etching method, also can both etching portal.The section in this hole or size are constant or change with the degree of depth with the degree of depth.

Emitter is most advanced and sophisticated form after, the material under should the tip in tip cambium layer or material the most handyly is selected from one group and comprises that dissolving, burn into evaporation, fusing or the technology that distils removes.As other places discussed, the whole substrate under the electron emission material layer also can be removed fully.In some cases, the whole material under the electronic emission material can be removed fully.

Barrier layer or material can also form before the deposit electronic emission material.Subsequently, this barrier layer can be removed selectively.

Field emission cathode construction of the present invention can be used as electron source.As other places discussed, a tip of this at least cathode construction can with another most advanced and sophisticated electric insulation, or at least one tip can be electrically connected with another electronic component.Certainly, field emission cathode construction of the present invention can use or become the part of an electronic console.

Following manufacturing process and corresponding figure are illustrated the generation of single structure.Though demonstrate a plurality of structures especially without any space pattern, but can make a plurality of structures simultaneously.

Figure 1A demonstrates the manufacture process of the simplest field emission structure 35 to 1C, on the field emission layer 30 field emission tip 31 is arranged.With consumptive substrate or basic unit's 5 beginnings, it can be the material of any suitable continuation course of processing, forms a hole or window 15, for example by means of photoetching technique.Substrate or substrate 5 can be single or multiple lift structures.That the shape in this hole 15 can be is square, circular, ellipse etc., and hole 15 can produce with any method well known by persons skilled in the art, and for example, hole 15 can be with the corrosion of reactive ion etching method, and its typical consequence can obtain the section shown in Figure 1A.Be to obtain optimum, the degree of depth in hole 15 should be greater than half of aperture.So this substrate or substrate 5 should be enough thick, can be fit to generate for hole 15.The influence that pore cross section changes will be discussed in the back.

One deck second expendable material layer 20 conformal deposited are to substrate 5, and the growth thickness on 15 sidewalls of hole converges to the center in hole 15, to cause a tip 21.Emitter layer 30 deposit fillings in the zone of tip 21 and other requirements, shown in Figure 1B.

Now, substrate 5 is removed by corrosion selectively.The top of this emission layer 30 or surface 32, promptly away from the face of emission tip 31, if necessary, the provisional deposit of available mechanical device or later removable masking layer or coating is protected.Then, remove layer 20 selectively, make most advanced and sophisticated 31 to expose, shown in Fig. 1 C.

On the other hand, if a little less than the adhesion between the layer 30 and 20, perhaps adopt releasing agent or thin releasing layer between layer 20 and 30, be intended to adhesion is done little, so, layer 30 just can peel from layer 20, in order to avoid need corrosion substrate 5 and layer 20, also can obtain the result of structure shown in Fig. 1 C.Be used for releasing agent or thin releasing layer between the layer 30 and 20, this will depend on the material as layer 20 and 30.

Show that as Figure 10 field emissive cathode 35 also can apply or coat one deck 29, and the result can be a kind of field emissive cathode 38 that applies or coat.This layer 29 must be a kind of material that can emitting electrons under electric field action.So obviously, if " emitter tip " can apply or coat one deck electronic emission material, so, emitter layer 30 just can be manufactured by any material, as long as can allow subsequently to apply or coat " emitter tip " 31 with electronic emission material 29.Shown in Fig. 1 D, at the back side 32 of emitter layer 30, people can also be provided with a coating or supporting course 26.

Above-mentioned basic technology method extends to and produces negative electrode 40, an emitter most advanced and sophisticated 41 of formation and the inside autoregistration of integrated extraction electrode 10.For making electrode 40, electrode layer 10 is deposited on consumptive basic unit or the substrate 5.There are an opening or window 38 in hole 15, generally adopts reactive ion etching through-electrode layer 10, enters substrate 5 degree of depth and forms greater than half and photoetching of hole 15 diameters, shown in Fig. 2 A.Certainly, substrate 5 should be enough thick, is fit to form for hole 15.

One insulator layer 25, conformal being deposited on the electrode layer 10, and the hole 15 on filling basic unit or the substrate 5 form tip 26.Then, emitter layer 30 deposit fillings in tip 26, shown in Fig. 2 B.

This consumptive basic unit or substrate 5 be from the structure back, optionally corroded to divest, shown in Fig. 2 C.

So, with opening or the window 38 in the insulator 25 selective corrosion through electrodes 10.Fig. 2 D represents the cathode construction 40 that obtains, have one with integrated extraction pole 10 inner self aligned cathode points 41.Concerning isotropic etching 32, the section of corrosion is illustrated among Fig. 2 D, and at this moment Section line 34 is exactly to draw the corrosion section of gained, only otherwise use optionally anisotropic etch process corrosion removal insulator layer 25, will obtain this result.

Further this basic technology of exploitation makes emitter tip autoregistration in a plurality of available electrodes of drawing and controlling as electron stream of formation.Structure 45 shows that a negative electrode has two and draws/go out control electrode.Just as shown in Figure 3A, this structure still on expendable substrate 5 deposition of electrode layer 10 begin to make, in deposit deposition insulating layer 12 on the electrode layer 10, then deposition of electrode layer 14 is on this insulating barrier 12.The corrosion penetrated bed 14,12 and 10, to or stretch into expendable substrate 5, photoetching has formed hole or window 15.

In addition, proceed down as preceding technology, conformal deposition insulating barrier 25 forms a tip (not shown), deposit emission layer 30, fill tip, remove expendable substrate 5 by peeling off or corroding, and after this, optionally etching insulating layer 25, expose emitter tip 51 from the bottom, shown in Fig. 3 B.The degree of exposing change on demand, as long as this change etching time.Fig. 3 B illustrates the layer that once filled up hole 15 with isotropic etch and 25 obtains corroding section 32.When adopting isotropic etch, a part of insulating barrier 12 also is subjected to etching.Significant sapping does not conform in the purpose of using, and in fact because of weakening this structure, and take the more space scope again, perhaps harmful.This sapping adopts anisotropic etching, as the reactive ion etching method, can eliminate.As long as replace etch layer 25, just should obtain the corrosion section that Section line 34 provides with anisotropic etching.

Reactive ion etching helps their anisotropy and the processing of absolutely dry method, but selection is not always all arranged, and is decided by the marked difference of etch-rate between different materials.What some wished the reactive ion etching processed will depend on material, as the sort of method that manufacturing structure 45 proposes, get rid of insulant 25 and expose emitter tip 51, do not have sapping, in fact the etch emitter material is very slow, but is enough to desirably not reduce most advanced and sophisticated 51 radius.If such problem takes place, a kind of method of compensation as other places narrated, the tip is pointed.

Another way is that Fig. 4 A shows to 4C how body can be avoided in this harm, and expresses and how to use an example on barrier layer.Bipolar electrode (adding emitter) field emission cathode construction 45 is used to explain.All the same up to all process steps that forms tip with those paragraph narrations of front.After forming tip, the very thin barrier layer 28 of one deck that is used for protecting this tip profile is deposited and covers on the layer 25.This barrier layer can be anyly can form film, can protect prong structure, optionally remove and can not damage other cathode constructions and stable as to be enough to and structure of finishing and the material of depositing.Lift one can with doped silicon electrode, doped silicon emitter, and a kind of like this material of using together of silicon dioxide insulator thing be silicon nitride, it optionally is dissolved in hot phosphoric acid.Emitter layer 30 is deposited on the barrier layer 28 and fills tip, shown in Fig. 4 A.

This is after peel off or corrode and remove substrate 5.And insulating barrier 25 reactive ion etching process etching is exposed barrier layer 28, shown in Fig. 4 B, does not also have sapping electrode 10 or 14.

Can emitter tip 51 be exposed to barrier layer 28 electing property etchings now, and finish this structure 55, shown in Fig. 4 C.

All above-mentioned examples have all been illustrated hole 15 and have been had sidewall section traditional, anisotropic etching, approximate vertical.Section although it is so can produce the structure that works, but such section can have many variations, equally also the characteristic that can produce the structure that works and other purposes are arranged.

Fig. 5 A illustrates a kind of section of hole of typical formation tip, else causes the section in the hole of tip and Fig. 5 B and 5C illustrate some.Hole 15,16 and 17 just showing on the simple continuous substrate, in any case but they be not limited to these examples and also can be produced on the multi-electrode of discussing the front or multi layer substrate or composition usually.

Fig. 5 A expresses the hole 15 of vertical sidewall, and it has been used in the above-mentioned technology.It has the advantage that takies the minimum space surface area.One of its feature is, the tip 21 of this tip is formed on the horizontal plane of substrate surface 62 at first, and if proceed conformal deposition, most advanced and sophisticated 21 can move vertically upward, shown in Section line 22, to being higher than this surperficial position, it is highly then controlled by the total amount of additional deposit.Under the condition of some deposit, 15 districts may form minority cavity 23 in the hole.Because these materials in the hole 15 will be removed later on, reveal the most advanced and sophisticated (not shown) of emitter, the present invention can not damaged in these cavities.

Many application scenarios are shown in field emissive cathode 35(Fig. 1 C), the position at emitter tip 31 may be inessential, still, but requires to have the position at better emitter tip in the application of use supplemantary electrode.Some electric field patterns proposes, the optimum position at this emitter tip will be on the top and a height between the end height of the electrode layer of close emitter layer.

A kind of method of adjusting this position is to adjust the section in vacuum area hole.The case representation of such section is in Fig. 5 B, and the size of this pore cross section changes or changes with the degree of depth here.Hole 16 has angled side walls, makes conformal thin-film 20 perpendicular to the angled side walls growth, forces to meet at first apart from the equidistant point of sidewall and bottom, and it is a lot of that this selects the end face that is lower than substrate 5.Additional deposit shown in Section line 22, can make tip move up and can select the position of tip, and the nominal of tip is settled perpendicular to desired position.The change that this just allows processing moves up and down tip up to desirable scope.By means of the angle of the position of suitably choosing nominal and vacuum area hole wall, worker's difference of accumulation can be absorbed, and this tip will be stayed in its optimum position scope.

The complicated hole shape of Fig. 5 C explanation also can be in order to produce useful prong structure.In the present embodiment, electrode layer 10 forms hole 17 by photoetching on substrate 5, at first, by anisotropic etching electrode 10, then selects isotropic etching substrate 5 for use.Deposit conformal layer 20 produces tip 21, and may produce cavity 23.Should be noted that this empty 23 can not influence this structure of successful use removes to form the most advanced and sophisticated (not shown) of emitter, because follow-up technology can be removed the cavity, so that expose the emitter tip.

Fig. 6 is that the conformal processing of much tortuous degree can also be in order to an example of the prong structure that is formed with usefulness.In the present embodiment, the hole 15 of nominal vertical wall is positioned on the substrate 5, and sputter applies upper strata 27.This tip that produces has following feature.At first, tip must have opening and thereby more easily fill up.Secondly, tip can form lower than electrode surface naturally, and does not need the hole shape of special-purpose region of no pressure.

Though sputtering deposit is a kind of incomplete conformal deposition branch, resembling quartzy these materials of sputter and be fine is again very stable insulant, and therefore can be formed with the prong structure 28 of usefulness.The usual problem that sputter brings is that it has the possibility that stays cavity or " rat hole " 29.Thereby the very big harm that concerning embodying semiconducter process, lies dormant of these cavities, for purposes of the invention, they but are harmless, because layer 27 will be removed from this after having formed the most advanced and sophisticated (not shown) of emitter.

The tip that makes very sharp-pointed is a desired shapes as the field emitter mould, but the infull mould of configuration also can utilize.Fig. 7 A illustrates the shape of conformal thin-film groove 71, just causes before side walls converge forms tip.Although this groove 71 is not to make very sharp-pointed, can also be used as mould, the emitter material deposit is entered.After removing substrate 5 and tip cambium layer or film 20, as described in prosthomere, emitter material 30 has the shape of approximate tip 72, and the sharper pure pinnacle of circle that is similar to is shown in Fig. 7 B.This approximate shapes can be used the technology that points that " technical background of the present invention " one joint narrated and point sharply, causes desirable sharp-pointed emitter 73, shown in Fig. 7 C.

Also can give to provide in the electricity structure that uses and isolate and interconnect a plurality of field emitters, extraction pole, and the device of other electrodes.This can accomplish, because electrode layer comprises normally good conductor of emitter layer.And therefore under accession one deck form between the projectile configuration before the insulation and interconnection, they photoetching can be made pattern.Equally, but relevant insulating barrier photoetching form to provide through hole to do perpendicular interconnection.A kind of to use such pattern of making be to constitute X and Y address line, chooses single when it can be used for display application or one group of emitter work.When make constituting integrated circuit and/or display, be together one group of single vacuum microelectronic device and/or display element electrical ties.

An embodiment of field emissive cathode interconnection is shown in Figure 8.In field emitter interconnection 80, emitter layer photoetching forms the line of each emitter 84 of interconnection, along " X " direction and constitute " X " emitter line 94.Space 88 is separated " X " emitter line 94 and another " X " emitter line 94.Equally, extracting electrode layer also is " Y " electrode wires 92 that photoetching forms, and with space 87 " Y " electrode wires 92 and another " Y " electrode wires 92 is separated.There, people can replace space opening 87 and 88 with insulating material.Insulate or tip cambium layer 85 separates each extraction pole 82 or " Y " electrode wires 92 with each emitter electrode 84 or " X " emitter line 94.That is what see is the tip 86 of regeneration, and that is from forming the result that emitter tip 81 obtains.Certainly, those skilled in the art can understand that this structure has one or more electrodes between emitter electrode and anode (not shown).This jockey allows a negative potential is added on the specific emitter 84 on " X " emitter line 94, a positive potential is added to start a specific emitter on a specific extraction pole 82 or " Y " electrode wires 92 again.

Described the present invention in detail although get in touch a concrete preferred embodiment, obviously, according to the narration of front, numerous replacements, modifications and changes one are established a capital and are understood to one skilled in the art.So, can expect that each additional claim will comprise any such replacement, modifications and changes, thereby fall among actual range of the present invention and the spirit.

Claims (11)

1, a kind of method of making at least one field emission cathode construction is characterized in that:

A) on substrate, provide at least one non through hole,

B) part at least a first material of deposit and the said at least hole of filling is enough to form tip,

C) the deposit material layer that one deck can emitting electrons under electric field action at least, and fill the part at the tip of said at least tip, and

D) remove beneath said first material of this tip, the part at the material tip of said electronics is exposed, so form said at least one field emission cathode construction.

According to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that 2, said hole is to comprise grinding, boring method, etching method, ion milling, peel off method or mould and annotate a kind of technology of method and form by being selected from one group.

3, according to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that, said hole is formed by etching, and the etching technique of employing is selected from one group and comprises anisotropic etch process, ion beam milling method, isotropic etching method, reactive ion etching method, plasma etching method or wet etching.

4, according to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that said first material is a conformal deposition.

5, according to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that said first material is made up of a releasing layer.

6, according to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that first material under the said tip is to be selected from one group of a kind of method that comprises dissolving, etching method, evaporation, fusion method or sublimed method to remove.

7, according to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that, before the deposition of materials of said emitting electrons, form a barrier layer.

8, according to the method for the manufacturing field emission cathode construction of claim 7, it is characterized in that, optionally remove said barrier layer.

According to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that 9, said tip is to do sharp selectively with being selected from one group of a kind of method that comprises isotropic etching at a slow speed or oxidation.

10, according to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that, form a supporting course at the back side of said structure.

11, according to the method for the manufacturing field emission cathode construction of claim 1, it is characterized in that, before the deposition of materials of said emitting electrons, form releasing layer.

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