CN1781195A - Method for making group III nitride devices and devices produced thereby - Google Patents

Abstract

A method is for making at least one semiconductor device including providing a sacrificial growth substrate of Lithium Aluminate (LiAlO2); forming at least one semiconductor layer including a Group III nitride adjacent the sacrificial growth substrate; attaching a mounting substrate adjacent the at least one semiconductor layer opposite the sacrificial growth substrate; and removing the sacrificial growth substrate. The method may further include adding at least one contact onto a surface of the at least one semiconductor layer opposite the mounting substrate, and dividing the mounting substrate and at least one semiconductor layer into a plurality of individual semiconductor devices. To make the final devices, the method may further include bonding the mounting substrate of each individual semiconductor device to a heat sink. The step of removing the sacrificial substrate may include wet etching the sacrificial growth substrate.

Description

The manufacture method of III nitride devices and by the device of its making

Technical field

The present invention relates to semiconductor applications, relate to ultra-thin III group-III nitride base semiconductor or the manufacturing of electronic device and relevant device such as light-emitting diode (LED) and laser diode more precisely.

Background technology

III group-III nitride compound semiconductor device comprises luminescent device and electronic device.Can cut out luminescent device with the component of film, so as emission from faint yellow until the light in green, blue, the Zhongdao ultraviolet ray range.Carry out appropriate combination by means of luminescent device, or fluorescent material is joined these devices, also might produce " white light " with other color.The emission mode of this device can be incoherent, is called " light-emitting diode " (LED), perhaps can be concerned with, and the device of this moment is called as " laser diode " (LD).Electronic device can also comprise High Electron Mobility Transistor (HEMT), heterojunction bipolar transistor (HBT), Schottky, p-i-n and metal-semiconductor-metal (MSM) photodiode etc.

Sapphire is to be used for one of primary material of growing GaN film and making blueness and green LED.Also can obtain because its cost is relatively lower, so become the material of frequent employing from market.Because the properties of transparency of Sapphire Substrate makes light can launch effectively and be not subjected to stop too much, meets the demands so be produced on the brightness of the LED on the sapphire.

Unfortunately, the GaN film on the sapphire is owing to bad lattice mismatch (greater than 17%) has high defect concentration.A kind of method that solves bad mismatch of once attempting is the AlN low temperature buffer layer of growing earlier before growing GaN.The GaN layer is grown in height along on the AlN nuclear of c axle orientation.Though the GaN layer is polycrystalline technically, but still be suitable for making general LED device.But the typical dislocation density with the GaN film on the sapphire of resilient coating is about every square centimeter 10 ¹¹Though, evidence suggests by means of the thicker GaN film of growth, can reduce dislocation density owing to the minimizing of grain growth and grain boundary.This improvement is limited, and the thicker film of growth can make cost improve.

Make high performance device, sapphire problem is that its thermal conductivity is not as GaN, AlN, SiC, not even as Si.Thereby the result just is difficult to make the electric current of having relatively high expectations and inject produces the high-brightness LED of more heats.And the bonding of GaN on sapphire is very strong, thereby is difficult to remove, and sapphire is an insulator.These have all increased the manufacturing step of producing LED.Because electrical lead all on the same side of diode, so size of devices is bigger, is produced on the number thereby the minimizing of the diode on the unit are.

To on sapphire, make laser diode (LD), also run into identical problem, promptly high defect concentration and bad thermal conductivity, they have limited current density, thereby have limited the power output of laser.And, owing to the GaN film is made up of poly grains, so be difficult to produce the smooth surface of resonant cavity.As a result, the mode configuration of laser is just inferior.

Developed another kind of method, the method produces with epitaxial lateral overgrowth (ELOG) has the bigger GaN crystallite dimension and the sub-district of fabricating low-defect-density.The LD that is formed by these selected low defect regions has manifested improved performance really.Unfortunately, whole process quilt is complicated, and the technology cost is higher, and the rate of finished products of LD is very low.

The method of an accommodation is to adopt SiC to come the growing GaN film as substrate.Compare with sapphire, SiC has obtained very big improve (less than 3.5%) to the lattice match of GaN.Theoretical defects density also greatly reduces, and is about every square centimeter 10 ⁹Perhaps the most important thing is among all these that compare with the polycrystalline film on the sapphire, the GaN film that is grown on the SiC substrate with low lattice mismatch can be considered to single crystal film.

But the GaN film of growing high-quality also exists some problems really on the SiC wafer.At first, because the SiC crystal is difficult to growth, SiC wafer costliness.The SiC crystal is to be produced by the physical vapor transportation method under very high temperature (being higher than 2200 ℃) with specially designed sealed vacuum reative cell.Secondly, because the high rigidity of SiC is near adamantine hardness, so cutting and polishing process are also very expensive.Moreover, the thermal coefficient of expansion (4.2 * 10 of SiC ^-6/ ℃) with respect to (5.6 * 10 of GaN ^-6/ ℃) less, also be debatable, because this may make the GaN film be under the stress state, thereby cause and break in the cooling procedure after growth.

In order to reduce this breaking, before final GaN film grown, the special AlGaN multilayer film of can on the SiC wafer, at first growing.Identical each layer also is used for reducing as far as possible the bandgap offset between SiC and the GaN.Utilize this skew that has reduced as far as possible, might utilize the favourable characteristics of SiC substrate conductivity, set up GaN LED with conventional design.This has reduced the size of LED significantly, and the rate of finished products of unit are also is higher than from fabricated from sapphire significantly.Higher rate of finished products has compensated the expensive of backing material.SiC also has the high advantage of thermal conductivity.This adopts the SiC substrate should make LED and LD work better with fabricating low-defect-density.

The intrinsic quantum efficiency that is produced on the GaN LED on the SiC is better than on the sapphire really.But the total outside luminance range of the last GaN LED of SiC.This is because SiC is so not transparent to the emission light of GaN, causes the light of signal portion to be blocked.For ultraviolet LED, situation is all the more so.On the other hand, owing to can obtain good cleaved surface, the performance of the last GaN LD of SiC is much better.The beam quality of laser has much simple mode configuration, thereby is more suitable in the application of DVD type.The high-termal conductivity of SiC substrate means that also higher electric current can be applied to LD, thereby has improved power output.

The result that sapphire and SiC go up the GaN film has shown a common conclusion of further improving LED and LD performance, and promptly the GaN film for the growth fabricating low-defect-density exists demand.In other words, substrate should have the lattice constant of closely mating with GaN.And substrate also should be transparent, and has good electrical conductivity and thermal conductivity.At present, unique substrate that can satisfy all these requirements is monocrystalline GaN substrates.Unfortunately, it is also insufficient to produce the technology of this monocrystalline GaN substrate.

The UNIPRESS of Poland has developed high-pressure process and has come the real monocrystalline GaN of production size until 1 centimetre thin slice pattern, but this may not be the large-scale production process of commericially feasible.Other unit such as the Samsung of the Lincoln laboratory of ATMI, the U.S. and Korea S has successfully produced and has been of a size of several centimetres thick independent GaN wafer.Unfortunately, the thermal coefficient of expansion of mismatch makes wafer bending easily and breaks after growth.In order to separate GaN, used laser ablation technology from sapphire.The GaN wafer that takes off still needs polishing to use.

The material that another kind has good potentiality may be the single crystal AlN substrate.Produced little monocrystalline under the hot conditions of SiC, transporting technology with physical vapor.Growth technique still is in the development phase, may also can not get high-quality AlN wafer in a lot of years future.And AlN is an insulator.So the manufacturing of device will face with sapphire on identical restriction.

Another accommodation is to seek a kind of substrate that substitutes that has good lattice match with GaN.On this substrate, after the GaN film grown, can take off and substitute substrate, so that obtain independently monocrystalline GaN film.If this GaN film has suitable thickness, will be enough firm, then can be used as the substrate wafer of making GaN LED and LD.For example, SUMITOMO CHEMICAL adopts GaAs to combine with the ELOG technology as substituting substrate, can produce the independent GaN wafer of 2 inch diameters.After the thick film of growing GaN, remove the GaAs substrate with chemical corrosion method.Because the GaN surface is very coarse after growth, produces level and smooth surface so need polish.Whole technology still has been complicated, the cost of wafer thereby height.The independent GaN wafer of SUMITOMO CHEMICAL is c surface (a 0001) orientation.Because big lattice mismatch (greater than 45%) between GaAs and the GaN is so the independent GaN wafer of SUMITOMO CHEMICAL is a polycrystalline.

In U.S. Patent No. 5625202, Chai discloses the compound that a big class is suitable as the backing material of growing GaN and AlN single crystal film.In the compound of enumerating, LiAlO ₂(LAO) and LiGaO ₂(LGO) best potentiality have been manifested.This is because the Clusky melt vertical pulling technology of cutting of the enough standards of energy is produced large-sized LAO and LGO monocrystalline.The technology of production major diameter high quality single crystal substrate has been arranged at present, and on LAO and LGO substrate, demonstrated the GaN growth for Thin Film.

In growth course, notice,, produce the chemicals of GaN film and the compatible non-constant of LGO substrate although two kinds of crystal have best lattice match and almost completely identical crystal structure.The chemicals of GaN film grown can corrode the surface of LGO in growth course.And even the GaN film can be grown on the LGO substrate, the also non-constant of the adhesiveness of GaN film is so can peel off inevitably owing to the mismatch of thermal coefficient of expansion after growth.

LAO has crystal structure and the crystal symmetry very different with GaN, and GaN is six sides symmetries, and LAO is the four directions symmetry.However, the two dimension of LAO (100) surface still has the m face (10 with GaN 10) structure much at one and lattice dimensions.Along the axial lattice mismatch of a of GaN is+1.45%.Along the axial lattice mismatch of the c of GaN only is-0.17%.LAO is also much better to the chemical compatibility of GaN growth chemicals.Wherein most important perhaps is that the LAO wafer can easily be eliminated with acid corrosion method used after growth.Utilize this unique character, used HVPE (epitaxial growth of metal hydride vapor transportation) method, having produced thickness is the independent monocrystalline GaN wafer of 150-500 micron.It is (10 that the monocrystalline GaN wafer that is produced by the LAO substrate has index 10) m planar orientation.This is different from obtainable all other independent GaN wafer on the market significantly, because the latter has the c planar orientation of index for (0001).These wafers are disclosed U.S. Patent No. 6648966, and are published among the U. S. application no.U.S.2003/0183158, and the two is all assigned in assignee of the present invention, and its whole contents is listed in reference herein.

Substrate is can be enough simple acid corrosion method used easily to be removed, and is LAO and compare a desirable character that is had such as sapphire with the more common substrate the SiC.Other potential substrate with potentiality of easy removing comprises GaAs and Si.The two is to all non-constant of the lattice match of GaN (greater than 45%).The ability of peeling GaN film does not provide big flexibility in designs with in making.

The U.S. Patent No. 5917196 of Teraguchi has proposed a kind of at LiAlO ₂The method of growing GaN base laser structure on the substrate.Reported a kind of purple light laser diode of under 430nm, launching with the threshold voltage of 10V.But fail the removing of open substrate, so its resulting devices may still have two contacts as above-mentioned Sapphire Substrate.

When the dielectric substrate disposed such as sapphire, in order to make LED or other device, need extra step, thereby need extra cost.In order to reduce the cost of LED, develop some technologies and removed insulating barrier, make the device can be manufactured as conventional GaAs LED.These technologies comprise mechanical lapping and ablate with short wavelength laser.Under two kinds of situations, reset procedure is all very slow, thereby is not suitable for large-scale production.And the GaN surface after substrate is removed is very coarse, requires mechanical polishing or reactive ion etching (RIE) to come level and smooth GaN surface.With this extra effort, produce new device architecture.This method has been carried out in some laboratories, and is as described below.

People such as Wong have discussed and have utilized wafer bonding and stripping means to carry out integrated (W.Wong, T.Sands, N.Cheung, etc., Compound Semiconductor Vol.5, p.54,1999) of blue GaN membrane structure and different substrates.Their nitride based devices of having grown on Sapphire Substrate is bonded to silicon wafer with adhesive with top surface then.Short wavelength laser is focused on the back side of GaN by sapphire, thereby has decomposed extremely thin GaN film.Because Ga is a liquid and N is a gas, so sapphire is peeled away.By means of with the adhesive dissolving, the nitride parts have just been formed.These parts can be transferred to another substrate.If this parts surperficial coated has Pd and In, then can be placed on the new substrate that also is coated with Pd by upside-down mounting.Heating makes the In fusing that is dissolved among the Pd, thereby forms firm permanent bonding.The GaN LED of blue-light-emitting is bonded to silicon substrate down with this technology p side.

Hewlett-Packard has reported that the Multiple Quantum Well nitride LED is to the transfer of conductive matrices substrate (Y.K.Song et al., Appl.Phys.Lett., vol.74, p.3720,1999).Device architecture is to be grown on the standard sapphire wafer with the OMVPE method.The Ni/Au contact is deposited on the p type GaN:Mg layer of top.Electrochemical growth copper film on top surface then, sample is installed on the new matrix such as silicon by flip-chip.After removing sapphire, n type layer is formed new surface contact with laser ablation methods.The luminescence peak of device is at the 450nm place.

LumiLeds Lighting company has reported a kind of high-power AlGaInN flip-chip LED design (J.J.Wierer, et al., Appl.Phys.Lett., vol.78, p.3379,2001).This device is compared with conventional small size (about 0.07 square millimeter) LED, has big light-emitting area (about 0.70 square millimeter).Flip-chip design provides big light-emitting area.Good thermo-contact make electric current can be bigger and forward voltage can be lower, power conversion efficiency thereby higher.About in July, 2002, LumiLeds has introduced the Luxeon of the 1W of a single 1mm * 1mm LED of a kind of employing ^TMThe Luxeon of the 5W of device (Tj=25 ℃, 425nm, 259mW continuous wave under 350mA and the 3.27V, 22.6% wall outlet efficient) and 4 single 1mm * 1mm LED of a kind of employing ^TMDevice (Tj=25 ℃, 425nm, 1100mW continuous wave under 700mA and the 7V, 22.4% wall outlet efficient).In their design, Sapphire Substrate still is covered with the LED top.In order to reduce electrical sheet resistance, the contact of p knot is in the bigger pectination solder joint, and the n knot is in interdigitated.The RIE (reactive ion etching) that need have litho pattern provides and electrically contacts.

Xerox has reported and has adopted the transfer (W.S.Wong et al., Mat.Res.Soc.Symp.Proc.V.639, p.G12.2.1,2001) of the nitride laser of laser-stripping method to copper substrate.Adopt the MOCVD method, the ridge waveguide laser structure is grown on the Sapphire Substrate.The Metal Contact of the two little belt shapes on the ridge of dry etching is deposited on the p type surface, top.This structure is removed sapphire with laser ablation methods then then by upside-down mounting and be fixed on the interim silicon wafer.After being in the hydrochloric acid new n type GaN surface corroded, the indium film is deposited thereon.This indium film be used to then with the LD parts be bonded to copper heat sink on, and remove interim silicon substrate.

University of South Carolina has reported with flip-chip the GaN LED of ultra-violet light-emitting has been bonded to silver-plated copperhead portion, obtain emissive porwer very high under the room temperature (A.Chitnis et al., Mat.Res.Soc.Symp.Proc.Vol.743, p.L7.7.1,2003), because copper has formed effective heat sink, and silver provides good reflection for the light of advancing downwards.

For the laser structure of GaAs base, reported similar lift-off technology.The bell communication research chamber has been reported with middle AlAs floor to remove GaAs substrate (E.Yablonovitch et al., IEEE Phot.Technol.Lett., Vol.1, p.41 (1989)) from LD structure wet etching.At first with on the GaAs substrate, the grow LD of routine of MOCVD method.With the hydrofluoric acid of dilution, remove the GaAs substrate by means of the dissolving of AlAs, make the extension parts can free floating.These parts that comprise a plurality of LD are used as the wax clamping of holder.Before peeling off, finish all procedure of processings, comprise with caustic solution and determine stripe type laser and metallization.This structure is installed on the new glass or silicon substrate then, and removes wax.

The red AlGaInP LED of transparent substrates can obtain on market.Typically say, Hewlett-Packard's LED structure of on the GaAs of lattice match substrate, having grown, but the GaAs of black tends to absorb red light only about half of of emission.Therefore, after finishing the AlGaInP device, thick lattice mismatch GaP layer is grown on the top surface, so that carrier is provided.Though this roof carrier has been full of fault of construction, these defectives can not propagated and get back in the active area.Remove the GaAs substrate with the wet chemical etching technique method then.The device thin slice is placed on the new transparent high-quality GaP wafer and sintering subsequently.Cut out each individual devices then.Have been found that extremely thin film is to be difficult to contact, and exist the problem of high spreading resistance.And extremely thin led chip is owing to waveguide suffers from out optical issue, thereby suffers from the parasitism absorption problem of contact and edge.So it just may be very useful that thick transparent substrates is installed.

Summary of the invention

Consider above-mentioned background, the purpose of this invention is to provide the method for a kind of making such as luminescent device, the method is more direct, and produces and to have such as thin active area required job specification and to have easily the therefrom device of heat dissipation capability.

Utilize the method for following at least one semiconductor device of making, provide according to this and other purpose, characteristics and advantage of the present invention, the method comprises the following step: provide one to comprise lithium aluminate (LiAlO ₂) sacrificial growth substrate; Form the semiconductor layer that at least one comprises the III group-III nitride of contiguous sacrificial growth substrate; Substrate surface will be installed sacrificial growth substrate will be fixed at least one semiconductor layer vicinity; And removing sacrificial growth substrate.The method can also comprise at least one contact is joined on the surface in the face of at least one semiconductor layer that substrate is installed, and substrate will be installed be divided into a plurality of individual semiconductor device with at least one semiconductor layer.In order to make final devices, the method can also comprise the installation substrate bonding of each individual semiconductor device to such as comprising the heat sink of indium (In).

Or rather, the step of remove sacrificing the property substrate can comprise sacrificial growth substrate is carried out mechanical lapping and wet etching.Therefore, in certain embodiments, substrate is installed is can be selected to the corrosion of moisture-resistant method.Install substrate can not other embodiment of moisture-resistant method corrosion in, mechanical lapping may be the method for optimizing of removing substrate.When the needs wet etching, can protect part that the influence that substrate is avoided wet etching is installed.

Sacrificial growth substrate preferably comprises monocrystalline LiAlO ₂, and at least one semiconductor layer preferably comprises at least one mono-crystal gallium nitride (GaN) layer.This combination of material can produce on demand has m face (10 10) Qu Xiang GaN layer.

The step of fixed installation substrate can comprise: form adhesive layer at least one semiconductor layer; And adhesive layer is bonded to the installation substrate.For example, adhesive layer can comprise at least a in (Au) of nickel (Ni) and gold.

Substrate is installed is comprised at least a in copper (Cu), silver (Ag), gold (Au), aluminium (Al), chromium (Cr), nickel (Ni), titanium (Ti), molybdenum (Mo), tungsten (W), zirconium (Zr), platinum (Pt), palladium (Pd), the silicon (Si).At least one semiconductor layer can be doped.In addition, the method can also comprise the resilient coating that forms between sacrificial growth substrate and at least one semiconductor layer; And wherein, remove sacrificial growth substrate and also comprise this resilient coating of removing.

Can produce extremely thin active part according to the present invention.For example, the thickness of at least one semiconductor layer can be less than about 10 microns.Certainly, one or more semiconductor layer can be selected to be electrically biased luminous.

Another situation of the present invention relates to the semiconductor device of making according to said method.Exactly, this device can comprise heat sink and contiguous heat sink installation substrate, and the installation substrate comprises in metal or the silicon at least one.This device can also comprise and the heat sink opposite a plurality of semiconductor layers installing on the substrate and determine at least one p-n junction that are placed in.These semiconductor layers preferably can comprise m face (10 10) Qu Xiang monocrystalline III group iii nitride layer.This device can also comprise and the opposite only contact that is placed on the semiconductor layer in the top of substrate is installed.This III group-III nitride can comprise for example gallium nitride.

This device can also comprise the adhesive layer of installing between substrate and the semiconductor layer.This adhesive layer can comprise at least a in (Au) of nickel (Ni) and gold again.Can comprise indium (In) or the indium base low-melting alloy such as indium-Yin or indium-Jin to the bonding material that substrate is installed.In addition, substrate is installed and is comprised at least a in copper (Cu), silver (Ag), gold (Au), aluminium (Al), chromium (Cr), nickel (Ni), titanium (Ti), molybdenum (Mo), tungsten (W), zirconium (Zr), platinum (Pt), palladium (Pd), the silicon (Si).Certainly, a plurality of semiconductor layer can be luminous in response to being applied to metal substrate and heat sink electrical bias.

Description of drawings

Fig. 1-the 7th is according to the perspective illustration in the device manufacturing processes of the present invention.

Fig. 8-the 10th is according to the diagrammatic side view in the device manufacturing processes of the present invention.

Figure 11 and 12 is according to the perspective illustration in the device manufacturing processes of the present invention.

Figure 13 be according to of the present invention from the wafer the perspective view of the individual devices of adjacent devices after separating.

Figure 14 is the diagrammatic side view that is fixed to the device shown in Figure 13 of holder.

Figure 15 is the reflection measurement data and curves according to the device of first embodiment of the invention.

Figure 16 is the reflection measurement data and curves according to the device of second embodiment of the invention.

Figure 17 is the reflection measurement data and curves according to the device of third embodiment of the invention.

Figure 18 is the reflection measurement data and curves according to the device of fourth embodiment of the invention.

Embodiment

Following reference wherein shows the accompanying drawing of each preferred embodiment of the present invention and describes the present invention more fully.But the present invention can be embodied in many different forms, should not be construed as limited to each embodiment described herein.It is in order to make the disclosure thorough and fully and for scope of the present invention is conveyed to person skilled in the art fully that these embodiments are provided.Similar reference number is represented the element that all are similar, and main symbol is used to represent element similar in the flexible embodiment.

The present invention relates to III group-III nitride compound semiconductor device.This device comprises luminescent device and electronic device.Can cut out luminescent device with the component of film, so as emission from faint yellow until the light in green, blue, the Zhongdao ultraviolet ray range.Carry out appropriate combination by means of luminescent device, or fluorescent material is joined these devices, also might produce " white light " with other color.

The emission mode of this device can be incoherent, as LED, perhaps can be concerned with, as LD.Known to the one skilled in the art, this electronic device can also comprise High Electron Mobility Transistor (HEMT), heterojunction bipolar transistor (HBT), Schottky, p-i-n and metal-semiconductor-metal (MSM) photodiode etc.These devices can be ultra-thin, and break away from initial substrates.They can be bonded to the metal or the semiconductor-based end with high conductivity and thermal conductivity.Effectively heat radiation has strengthened the performance of device, and makes it possible to make broad area device.

A kind of new method that is used for ultra-thin GaN LED of large-scale production and LD has been described.Depend on the component of film, this technology can produce emission wavelength from deep ultraviolet to green or above LED and LD.The method makes it possible to produce independently the Ultra Thin Epitaxial film and need not be fixed to initial substrates, and aspect chemical constituent, have big flexibility, including, but not limited to simple GaN and AlN binary system, AlGaN and InGaN ternary system even AlInGaN quaternary system.The method also makes it possible to make the very large LED of area that routine techniques can not be produced.Large area LED has reduced manufacturing cost significantly, and can produce the brightness higher than conventional LED.

(100) orientation LAO single-crystal wafer 30 (Fig. 1) that this production technology can start from polishing.The surface of wafer 30 is cleaned fully.Then LAO wafer 30 is placed unshowned MOCVD (metal organic chemical vapor deposition) reative cell, and be heated to 700-1200 ℃, so that growing GaN epitaxial film 32 AlGaN, InGaN, the AlInGaN epitaxial film of specific Al, In, Ga metal ratio (or have).But MOCVD be not can the growing GaN epitaxial film unique method.Other available growing method comprises MBE (molecular beam epitaxy), ALE (atomic layer epitaxy), HVPE (hydride gas-phase epitaxy) etc.

The structure of epitaxial film 32 and component depend on the certain device that will make.An important feature is that the GaN epitaxial film 32 that is grown on (100) LAO substrate 30 is positioned at (10 10) be the m planar orientation, this is to be different from (0001) GaN film of being grown on any other known substrate that comprises sapphire, SiC, GaAs, Si significantly.LAO is the unique substrate that produces m face epitaxial film known at present.

At first consider typical blueness and green visible light LED herein.At first thin (less than 50nm) AlN, AlGaN of deposit or the low temperature buffer layer 31 of InGaN on LAO wafer 30 are so that help bonding epitaxial film 32.Though AlN is used as the resilient coating of growing GaN on the sapphire, AlGaN or InGaN layer can be preferably as the resilient coating of LAO substrate 30.Its reason is that it can provide LED and the required conductive substrates of LD device.And AlN is the poorest to the lattice match of LAO substrate 30, but can be used as resilient coating 31 fully.Al _0.7Ga _0.3N is along a axle and the accurate lattice match of LAO, and pure InGaN is best to c axialite lattice coupling.

In principle, any AlGaN component can both be used as resilient coating.Al _0.3Ga _0.7N may be the component of perhaps preferably compromising that obtains lattice match.The deposition temperature of this resilient coating 31 can change to 1000 ℃ from 500 ℃.But because the lattice match of 30 pairs of epitaxial loayers 32 of substrate is very good, so resilient coating 31 deposits of higher temperature (900 ℃) are preferred.This is different from other prior art significantly, because prior art typically requires to begin with low temperature (550 ℃) resilient coating.Comprise the growth on sapphire, GaAs, Si, the SiC substrate.

After grown buffer layer 31, temperature can be elevated to 950-1150 ℃, so that the ground floor GaN 32a that growth is mixed by silicon n.Thickness can change to several microns from hundreds of nm.In the prior art, because the removing of the substrate 30 that carries out with mechanical lapping or laser ablation all is destructive, so need thicker GaN guarantee that remaining epitaxial film 32 can not be damaged in substrate removing technology.According to the present invention, as following will be in more detail as described in, remove the technology of LAO substrate 30 and do not damage epitaxial film 32.Therefore, very thick the undoping or GaN that n mixes that have no reason to grow.The thickness of preferred n doped layer 32a can be about 800nm to 2 micron.

After finishing the GaN layer 32a that n mixes, as shown in Figure 2, can begin grows has the multi-quantum pit structure 32b of undope InGaN thin layer 32b and GaN thin layer 32c alternately.The two thickness of the InGaN trap 32b of this quantum well structure and GaN potential barrier 32c can change to 10nm from 1nm.The thickness of trap preferably is about 2nm, and the preferred thickness of potential barrier is about 5nm.After the grown quantum trap, the Mg doped p of can growing type GaN layer 32d is as the cap layer.The thickness of p layer 32d once more can be at hundreds of nm in several microns scope.So just formed basic p-n junction GaN diode structure.

In order to form LD, can increase the thickness of p layer 32d.This is because as following will further the explanation, and it may be desirable forming the anti-mesa structure that contrasts with conventional structure.

After finishing epitaxial growth, just take out LAO wafer 30 (Fig. 2) with GaN epitaxial film 32 from the MOCVD reative cell.Can be placed in the metal evaporator, so that with Ni (approximately 20nm) and gold (approximately 150nm) thin film cladding entire top GaN surface, to form p type ohmic contact 34 (Fig. 3).

Then, as shown in Figure 4, the superficial layer 34 of the metal coat of LAO wafer 30 is bonded to press polished planar metal or silicon wafer substrate 36, this substrate 36 can be held the whole LAO wafer that is typically 2 inch diameter sizes.This metal or silicon base 34 is as electrically contacting and heat sink.There are a large amount of metals to be suitable for this purposes, for example Cu, Ag, Au, Al, Cr, Ni, Ti, Mo, W, Zr, Pt, Pd.

Even silicon can not be considered to metal technically, but silicon obtains easily and is inexpensive.Coefficient of linear thermal expansion (4.7 * 10 ^-6/ K) be slightly less than (5.6 * 10 of GaN ^-6/ K), and the thermal conductivity of 80-150W/m ° of K also is acceptable.As bonded substrate is a kind of selection.All these metals are because very different physical propertys can be as the substrate of the LED with different engine requests.The selection of metallic substrates 36 depends on the simple and easy of the ductility of thermal conductivity and conductivity, thermal coefficient of expansion, antiacid corrosivity and metal and bonding.Most of metals have much higher thermal coefficient of expansion, and for example Al (23.5 * 10 ^-6/ K), Ag (19.1 * 10 ^-6/ K), Cu (17.0 * 10 ^-6/ K).Other metal has much more reasonable thermal coefficient of expansion, and for example Mo (5.1 * 10 ^-6/ K), W (4.5 * 10 ^-6/ K), Zr (5.9 * 10 ^-6/ K).Between remaining is in.

The big mismatch of thermal expansion can cause breaking of GaN film 32 in any heating process process such as forming good ohmic contact 34.In addition, considering the alloy property between metal bonding, corrosion resistance and the different metal, also may be desirable.

At last, considering the ductility (or molassity) of metal, may also be desirable.Owing to wish usually with extremely thin diamond saw GaN film 32 and metallic substrates 36 to be cut into single chip, the metal of preferably avoiding saw blade to be cut covers.Exist the concrete steps that can reduce this potential problems as far as possible.And, known to the one skilled in the art, can weave in advance metallic substrates 36 with the mode of the less chip that can make it to be divided into easily specific dimensions, simplify the manufacturing process of LED or LD.

The metallic substrates 36 of weaving is in advance aimed at (this aims at c axle and a axle of GaN again) with a axle of LAO wafer 30 and c axle, make when being divided into the less period of the day from 11 p.m. to 1 a.m, and the cleavage surface of GaN is aimed at the edge of metallic substrates, may be desirable.

The thickness of metallic substrates 36 can be led 500 microns from 50 microns variations.Perhaps the material of the metallic substrates 36 of wishing most is Cu (copper), because Cu is height heat conduction and conduction, and inexpensive and easy acquisition.But the problem of Cu is that antiacid corrosive nature is very poor, then need special steps to come sealed copper, in order to avoid in corrosion process, contact with acid.

Next preferred selection may be Si (silicon), Ag (silver) and/or Mo (molybdenum).These three kinds of materials have very different character, but all have antiacid common property.Therefore, can be applicable to other metal to a kind of step of metal exploitation.Difference is the metal bonding character and the ductility of material.For the purpose of illustrating, selected the metal of Ag as substrate 36.Same step also can be applied to Si or the Mo as base metal.

Thickness is that to be cut into diameter be 2 inches disc-shape 36 to 100 microns Ag sheet metal.Then, the LAO wafer 30 with metallization GaN side 34 is faced down is incorporated into circular Ag metal dish 36 with In (indium) alloy hot key, produces structure shown in Figure 5.Ag is the highest metal of a kind of conductivity and thermal conductivity (resistivity under its 20 ℃ is 1.63 μ Ω cm), and thermal conductivity is 429W/m ° of k).Even Ag has bigger thermal coefficient of expansion (19.1 * 10 ^-6/ K), but the bonding temperature that relates to may be much lower to tackle this problem.

Si and Mo have the thermal coefficient of expansion littler significantly than other metal and (are respectively 4.7 and 5.1 * 10 ^-6/ K), and more can compare with the thermal coefficient of expansion of GaN, but require higher thermal bonding temperature, cause on the overall function that partial heat expands can with the analogy of Ag metal.For fear of later peeling off, Ag, Si, the Mo metallic substrates must be very good to the bonding of Ni-Au applicator surface.Because the heterogeneity of metal has adopted different bonding materials.For the Ag metallic substrates, preferred bonding material is Indalloy ^R#3 (90In 10Ag).For the Si substrate, preferred bonding material is AuIn (a golden indium).For the Mo metallic substrates, preferred bonding material is AuGe (a golden germanium).

After on the GaN side 32 that Ag metallic substrates 36 is bonded in LAO wafer 30, whole slice, thin piece is at first placed on the grinder, so that most of LAO substrate is ground away, in thermohaline acid (HCl), soak then, so that dissolving and remove remaining LAO substrate 30 (Fig. 6).In order to prevent being corroded property of bonding metal sour eating away, can paste the edge of wafer 30 as sealing with epoxy resin.Though prevent metal edges along not difficult by acid corrosion, any pin hole of GaN film 32 or crack can both cause difficulty in corrosion process.In the case, the physical grinding that can place one's entire reliance upon is removed the LAO substrate.Because bonding more weak between GaN and the LAO is so the LAO substrate more than 90% is removed in the enough mechanical lapping of energy effectively.Have been found that the very anti-hcl corrosion of Ag metal.It forms one from the teeth outwards can easily use nitric acid (HNO ₃) the thin AgCl coating removed.Acid resisting metal preferably with similar quality is Si and Mo.Other metal of anti-hcl corrosion is W (tungsten), Au (gold), Pt (platinum).

With after removing LAO substrate 30, only stay the GaN film 32 (Fig. 6) that is bonded on the Ag metallic substrates 36 at hcl corrosion.The top surface of GaN film 32 is n types.Now just depended on the type of the resulting devices that will make, so can process whole block by following different mode:

(1) blue led of standard

For the blue led of production standard, slice, thin piece shown in Figure 6 is cleaned and dries.On the GaN surface, form n type ohmic contact solder joint then.Because only top side can be luminous, reduce the metal covering as far as possible so patterned contact solder joint is made into, and make enough areas can be luminous.Can at first use the aluminum metal coating top surface of 150nm then with the titanium of 20nm.Then, get rid of with photoresist and be coated with this surface.Form the figure of ohmic contact solder joint.Depend on LED size of devices and shape, the geometric figure of contact solder joint can be simple point, bar shaped or complications.The metal that exposes is corroded, and photoresist is peeled off, so that stay the solder joint figure.

Certainly, can be by means of at first using lift-off technology (Fig. 7) with photoresist 40 coated surfaces.The solder joint figure is formed on (Fig. 8) on the photoresist 40.With Ti and Al metal coating coating wafer top, determine 42a and 42b part (Fig. 9) then.Photoresist 40 is peeled off, just produced contact solder joint 42a (Figure 10 and 11).

The device that obtains will have excellent thermal conductivity, cause to access broad area device (greater than 1 square millimeter).The final size and the shape of led chip depend on purposes.Led chip just can be cut into any geometric figure such as strip, as long as device can dispel the heat rightly.Before cutting into little chip, the Ag metal back side is adhered on the sheet glass.Cutting process only needs to make otch 44 to go deep into wafer and is enough to cut and wears the degree of depth that the Ag metal level enters sheet glass 45 and get final product (Figure 11).Sheet glass 45 is used to clean cutting saw blade and handles the metal covering problem.

For Si or Mo metallic substrates 36, there is not the metal covering problem.So as the one skilled in the art is understandable, might use the stretchable replacement sheet glass that brings.

After finishing cutting, the slice, thin piece 50 that cuts is cleaned, so that remove cutting dust, in acetone, dissolve then, so that take off chip (Figure 13) from sheet glass.For the device of Si or Mo metallic substrates, might and be separated into single chip with the band stretching.Just can collect the chip of having finished then, and, be mounted to the final devices packaging part to be same as the mode of conventional red LED.This has just produced ultra-thin blue led.In order to obtain high brightness, shown in the embodiment, use by heat sink 48 of metal part 44 bondings effective heat sink (Figure 14) is provided as shown.Lead-in wire 46 also is fixed to top contact 42a.

(2) high brightness White LED

In order to make the White LED of high brightness, can use Ce-YAG or Eu-SrAl at the place, the back side of blue led ₂O ₄Or the fluorescent material reflector of other known ceramics coating, or on the top of the GaN face that n mixes the thick-layer of deposit n doped ZnS e.Utilize the fluorescent material reflector to produce white light, need not any extra wafer process step.But the ZnSe overlay for as fluorescent material has adopted extra deposition process.

After removing the LAO substrate, wafer is cleaned and is dry, places the ZnSe reactor then, so that with the n doped ZnS e layer coated surfaces on the n Doped GaN layer top.ZnSe layer can absorb the blue light of GaN emission, and launches the sodium yellow of itself, mixes with the blueness of GaN and white light is provided.

The thickness of ZnSe is Be Controlled on demand, makes it to have correct absorbability, thereby has correct white.In the case, n side ohmic contact can be formed on the top of ZnSe film.It is described that remaining deposition process is very similar to previous section.Cut crystal and form single led subsequent step in top (1).

The SrAl that Ce doped YAG or Eu mix ₂O ₄The ceramic reflecting device causes the state of white light not change with respect to light intensity (or drive current) to temperature-insensitive.On the other hand, the emission of ZnSe is very responsive to temperature.Along with temperature rises and red shift.So also red shift of state of white light with the rising of intensity (or temperature).Because can have the substrate of very large height heat conductive metal according to device of the present invention dispels the heat, so the variations in temperature of entire device is much smaller.Known to the one skilled in the art, this will reduce the color displacement effect significantly.And the applicant believes that this device is the combination first of ZnSe-GaN n-n-p device.

(3)LD

This LD structure is opposite with the conventional LD with the GaN substrate of n type and p type GaN table top.In the case, device has GaN substrate of p type and n type GaN table top.Basic manufacture process is substantially with recited above identical.Different with conventional LD design is not need thick film.

In order to prevent the leakage of light, the thick AlGaN covering that conventional LD design need have high Al content limits light.In order to prevent MQW (Multiple Quantum Well) structure breaking, GaN/AlGaN MD-SLS (modulation doping strained layer superlattice) layer is grown in MQW two sides.According to the present invention, the entire top on n type GaN surface will be metallized, so that form n-side ohmic contact.

The present invention adopts the metallization ohmic contact film that is used for light restriction on p side and the n side to replace being used for the use of the MD-SLS of light restriction.After the top on Ti that uses ohmic contact and Al metal coat n type GaN surface, with photoresist this surface is carried out graphically, so that mark the position of each laser diode.This ohmic contact figure is aimed at the cleavage surface of GaN film, causes the resonant cavity that might cleavage GaN film forms laser application.

RIE (reactive ion etching) can be used to form mesa structure.The p layer that this corrosion will penetrate GaN reaches and metallic substrates.The side of table top will be by the parcel of the absorbing material such as silicon dioxide to prevent reflection.

Then, the figure that produces according to RIE technology of wafer is cut to enter by metallic substrates and supports to use sheet glass.Cleaning with after removing cutting dust, sheet glass is placed in the flux, so that dissolved epoxy and discharge the LD chip.These chips are cleaned, dry, then along (0001) face at two ends by cleavage, to produce resonant cavity.

In order to reduce the threshold value that swashs radio stream, the GaN surface of two cleavage may need highly-reflective coating (by paired quarter-wave TiO ₂/ SiO ₂Multilayer is formed).So just these chips can be installed, to finish laser diode.

The detailed process of producing visible light and white light LED and visible light LD has so far been described.In order to produce ultraviolet LED and LD, except basic membrane component was AlGaN rather than GaN, general step was identical substantially with the step of making the visible light device.The raising of Al content will increase the band gap of AlGaN film, but simultaneously, the resistivity of film also can increase.

Pure AlN is a kind of insulator, so before device function is subjected to too many obstruction, maximum Al content is existed certain limit.The Al content that this limit is set in the AlGaN film usually is about 50%.Because the lattice constant of LAO is slightly less than GaN's, so in fact get better with the match of AlGaN component.In order to make ultraviolet LED, be after the AlGaN resilient coating of 900 ℃ of following initial growth thin (less than 50nm), at the AlGaN of a n doping of 1000-1200 ℃ of following deposit.Similar in appearance to visible light LED, preferred n doped layer thickness also is about 800nm to 1 micron.

Multi-quantum pit structure is made up of the alternating thin layers of GaN/AlGaN.The thickness of this quantum well structure is that each is to only being several nm.Known to the spontaneous polarization in sapphire with c face (0001) film orientation and the growth of the routine on the SiC and piezoelectric effect exist big internal electric field (approximately 1MV/cm).The red shift that this may cause quantum limit Rodney Stark effect to cause.Because film according to the present invention is along the growth of non-polar m face (1010) direction, so there is not this red shift under high strength excites.

After the grown quantum trap, AlGaN is as the cap layer for growth Mg doped p type.The preferred thickness of this p layer also only is hundreds of nm.This has just formed basic p-n junction ultraviolet light,long wave lGaN diode structure.

After growth p-n junction structure, remaining device fabrication and visible light LED's is identical.The emission of ultraviolet light is the GaN layer that mixes by n.Owing to electrically contacting solder joint, Ti-Al ohm exists very little the stopping of light to emission.In order to make ultraviolet LD, to change into the AlGaN from GaN except the component of film, step is identical once more.

Compare with LD with conventional LED on the SiC with being produced on sapphire at present, presented the characteristics and the advantage of many uniquenesses as described below according to the design of device of the present invention.

(1) LED and LD important feature is the superthin structure of GaN film, initial substrates need not be fixed thereon.The gross thickness of device can be thinned to 1 micron or below.There is not other technology to be believed to make so thin independent GaN device at present.Superthin structure helps heat radiation, and is particularly when device is bonded to the substrate of height heat conductive metal, all the more so.

(2) Fa She light is not stopped.LED of the present invention and LD design all are to have more transparent n Doped GaN side on the top with direct luminous flip-chip design.Proper metalization can further improve reflectivity on the LED back side, thereby improves total light output.

(3) this LED and LD comprise the extremely thin GaN film that is bonded on the height heat conductive metal base top.Exist in the bases of device excellent heat sink, cause with existing sapphire or even SiC base LED compare with LD, can be driven by bigger electric current more powerfully.

(4) this LED and LD adopt the abundant metallic substrates to p Doped GaN layer to electrically contact.This has reduced the influence of the low two-dimensional sheet electric current of low carrier concentration and p doped layer significantly.

(5) compare with the GaN film on the SiC with sapphire, the excellent lattice matching that defect concentration is lower makes the device can be by bigger current drives to produce higher brightness.

(6) because in the heat sink whole substrate that is in device, so the size of LED of the present invention can have than light-emitting area more much bigger on existing sapphire or the SiC.Because whole metallic substrates is an electrode, so flowing of electric current is out of question.The final size of device only is subjected to the restriction of the metallic substrates heat radiation limit.And the shape of LED no longer is confined to square slice, thin piece.Can make the LED of strip.Its length only is subjected to the restriction of initial substrates wafer diameter.This just provides the illumination that it is unique that existing LED is beyond one's reach.

(7) owing to replace with the AlGaN layer that begins to grow and to begin the growing GaN layer device is not had difficulties to UV transparent, so the structure of device is very suitable for ultraviolet LED and LD.And because film of the present invention is a kind of m facial mask, it is non-piezoelectricity, so there is not quantum limit Rodney Stark effect.The emission wavelength of device of the present invention will keep constant and power not tube device how.

(8) this structure provides natural cleavage surface for laser resonant cavity.

(9) do not need ELOG (epitaxial lateral overgrowth) or other complicated photoetching or corrosion process.The manufacture process of entire device is much simple.This LED has conventional installation and design, is entirely identical to the installation and design of red GaAs base LED and LD, causes before encapsulation is with formation LED group, and this device can be totally integrated on the chip level with GaAs base LED.

Generation is used for making the GaN of the electronic device such as High Electron Mobility Transistor (HEMT), heterojunction bipolar transistor (HBT), Schottky, p-i-n and metal-semiconductor-metal (MSM) photodiode and the basic step of AlGaN epitaxial film, is same as the epitaxial film that forms LED and the similar component of LD substantially.Unique difference is the detailed sequence of layer structure.Diode only needs p and two basic layers of n, controls photon radiation with quantum well.Under the situation of HBT or BJT (bipolar junction transistor) device, need 3 layers of n-p-n, p-n-p or other structure.Still can be provided for high complete metal substrate of dispelling the heat according to design of the present invention, this is that any high-power applications is mandatory.And for the device of MSM structure, this technology provides simple and the most direct design.

Embodiment of the present invention can be divided into two concrete steps.First step is with MOCVD method growing GaN epitaxial film.Second step is to make GaNLED and LD device by these epitaxial films.

(A)GaN The growth of epitaxial film:

In order to make GaN LED and LD, at first must have the high quality GaN epitaxial film, make device with the intermediate layer of ad hoc structure.The most basic requirement is that this film should be level and smooth, mirror status, and free from flaw.And this film should be able to be fixed to substrate and not peel off, so that can grow back processing.All films all use Aixtron 200 HTMOCVD systems to grow.Whenever, take turns the wafer that growth only produces one 2 inch diameter.The gas source of reactor comprises nitrogen (N ₂), ammonia (NH ₃), hydrogen (H ₂), silane (SiH ₄), trimethyl gallium (TMG), trimethyl aluminium (TMA), trimethyl indium (TMIn) and Cp ₂Mg.

The present technique field is understood that fully the growth of the film of particular components requires mobile suitable gas source to reach deposit.For example, the growth of AlN layer requires mobile ammonia and TMA to form reaction.The growth of GaN requires flow ammonia and TMG.The growth of InGaN quantum well requires flow ammonia, TMIn and TMG.Mix in order to reach n, require the silane that flows, and the p doping requires the Cp that flows ₂Mg.Therefore, in the following specific embodiment of embodiment of the present invention, will not provide the detailed description of gas stream.

The gas flow rate that is used to provide the best film component changes according to the reactor that different sellers provide with mixing ratio.Even the reactor for same seller provides also exists variation in different unit.

Embodiment 1:

The LAO wafer is cleaned, and is placed in the Aixtron 200HT MOCVD reactor.Growth technique is followed GaN growth step on the sapphire of standard.Substrate at first is preheating to 1050 ℃ and stopped 10 minutes in blanket of nitrogen.Temperature is reduced to 580 ℃, and growth thickness is the AlN low temperature buffer layer of 50nm on the LAO wafer.Then, temperature is elevated to 950 ℃, and the GaN that undopes of the 800nm that on the top of AlN resilient coating, grows.Reflection measurement is the result be shown among Figure 15.The state of film is level and smooth, and does not exist and peel off.

But TEM (transmission electron microscope) shows very different results.The crystallization of AlN layer is very poor, and the growth core of GaN film is provided on its top.Because the preferred orientation of AlN nuclear is along c axle [0001] direction, the result, the GaN film is c face (a 0001) film, rather than m face (10 10) film.So there is not the epitaxial relationship of GaN film and LAO substrate.This film is owing to low temperature AI N resilient coating presents high defect concentration.

Embodiment 2:

New LAO wafer is cleaned, and is placed in the Aixtron 200HT MOCVD reactor.The method of following us has changed growth step.At first cancelled substrate has been preheating to 1050 ℃ of steps that stop 10 minutes.Replace directly and wafer is heated to 900 ℃, then beginning deposit AlN under this high temperature.After the high temperature AlN resilient coating of growth 50nm, temperature is elevated to 950 ℃, and the n Doped GaN of the 800nm that on the top of AlN layer, grows: the Si layer.The reflection measurement data (Figure 16) of the flatness of monitoring film in growth course have shown the improvement significantly of film quality, and are different from the film quality of embodiment 1 significantly.

This film is a minute surface, and does not exist after cool to room temperature and peel off.Silicon doping is to the not influence of quality of film.When examining under a microscope, the GaN film is very even, and does not find the crack in film.The thermal coefficient of expansion of this and GaN is less than LAO, and the fact that causes the GaN film always to be in cooling procedure under the tension force is consistent.

TEM (transmission electron microscope) shows that the AlN layer is crystallization and extremely thin.We estimate that it may form alloy with GaN at the interface.Because the crystallinity of AlN resilient coating is better, so film is more even, and defective is less.

Embodiment 3:

In case established the n Doped GaN: the basic growth technique of Si epitaxial film just has the growth of the GaN film of complete p-n junction and quantum well structure.New LAO wafer is cleaned, and is placed in the Aixtron 200HT MOCVD reactor.We adopt that embodiment 2 sets up be used for the growing growth step of complete structure GaN film.Wafer is heated directly to 900 ℃, begins the thick AlN high temperature buffer layer of deposit 50nm then.After the growing AIN resilient coating, temperature is elevated to 950 ℃, so that the n Doped GaN of growth 800nm: the Si layer.Then, the quantum well structure formed by the InGaN trap of undope GaN potential barrier and the 5nm of two couples of 10nm of growth.P Doped GaN at the final 200nm of growth: before the Mg cap layer, the AlGaN barrier layer of growth 10nm on the quantum well structure top.

Reflection measurement data (Figure 17) have shown excellent growth conditions.After the growth of having finished p-n junction and multi-quantum pit structure, furnace is lowered to 750 ℃, stops 40 minutes, so that the GaN:Mg layer that p is mixed carries out thermal annealing and activation.After thermal annealing, reactor is cooled to room temperature.Similar in appearance to embodiment 2, the GaN film on the LAO is level and smooth and minute surface.Do not find the crack in the film of on whole 2 inches wafers, finishing.This wafer can be used for making the LED device.

Embodiment 4:

Above-mentioned 3 embodiment have illustrated the technology of the complete structure GaN film of growth visible light LED and LD device.Present embodiment will show can make ultraviolet LED and LD device.This means the AlGaN film of on LAO, to grow.The cellular lattice dimensions of AlN is less than GaN, a axle=3.112 dusts, c axle=4.995 dusts.Compare with the lattice dimensions of LAO, lattice constant is also littler.Mismatch along a axle is-0.7%, is-3.5% along the mismatch of c axle.In fact, AlN has the poorest lattice match in AlN-GaN solid solution compositional range.Al is approximately 30% AlGaN, has the lattice match best generally with LAO.

Therefore, in order to check the ability of grow thick AlN film on LAO, we will provide the necessary information of feasibility of the AlGaN epitaxial film of growth ultraviolet LED and LD.New LAO wafer is cleaned, and is placed in the Aixtron 200HT MOCVD reactor.At first directly wafer is heated to 900 ℃, then beginning deposit AlN resilient coating under this temperature.The growth 50nm the AlN resilient coating after, temperature is elevated to 950 ℃, and under this temperature continued growth AlN film.The AlN film of always finishing is about 350nm.

The reflection measurement data are shown among Figure 18, and these data are excellent.After cool to room temperature, the AlN film is equal even minute surface.When at test under microscope, whole 2 inches AlN film is not found visible crack.So just demonstrated the growth of the AlN film that undopes.Similar in appearance to the situation of GaN, AlGaN should be able to grow on LAO.

(B) manufacturing of GaN LED and LD device:

After as described in the embodiment 3 of top chapters and sections, having finished the growth of complete p-n junction and quantum well structure epitaxial film, take out LAO wafer from the MOCVD reactor with GaN epitaxial film, just can make the LED device.This wafer is placed in the metal evaporator, and at first uses the thick Ni of about 20nm, uses the thick Au film of about 150nm then, applies the top on GaN surface, so that form the ohmic contact of p-GaN layer.

Thickness is that to be cut into diameter be 2 inches disk to 100 microns press polished smooth Ag sheet metal.Then, the LAO wafer with metallization GaN side is faced down and is incorporated into the Ag rosette by the indium metal hot key.In the thermal bonding process, with suitable weight whole assembly parts are pressurizeed, so that after solidifying, guarantee good physics contact.

After the LAO wafer was strongly bound to the Ag metal dish, epoxy resin was applied to the edge with the LAO wafer of Ag Metal Contact.This will be in follow-up acid corrosion technology the edge of sealing metal sheet.In case epoxy resin is cured, just whole slice, thin piece is immersed in 50% hydrochloric acid (HCl) that dilutes of temperature, so that dissolving and removing LAO substrate.After the LAO substrate is removed by the HCl corrosion, wash wafer with the nitric acid that dilutes, so that remove the AgCl on the Ag metal surface.So, only stay the GaN film that is bonded to the Ag metallic substrates by indium alloy.This GaN film now with respect to supporting pieces by upside-down mounting.The top surface of GaN film is the n type.

Whole slice, thin piece is rinsed to remove acid, is cleaned, and is dried.So GaN film surface can be used for forming the ohmic contact solder joint of n doped side.Adopted lift-off technology to form the contact solder joint herein.Get rid of with photoresist and to be coated with GaN film surface.For the ohmic contact solder joint has formed figure.For the sake of simplicity, formed very large 100 microns round dot as the contact solder joint.In the device of reality, can change the size and dimension that electrically contacts solder joint, so that satisfy the demand.

Because device of the present invention has excellent thermal conductivity, so can obtain broad area device (greater than 1 square millimeter).Each Contact welding dot center that we make figure is 1.5mm to the spacing at center.In case figure is exposed to ultraviolet light, the photoresist that is not exposed just is stripped to expose the solder joint district.Then, the Al metal by means of the Ti that at first applies 20nm applies 150nm again forms n type ohmic contact solder joint.Peel off photoresist by means of the metal film on the photoresist top, just obtained staying the Ti-Al Metal Contact solder joint that is used for n-doped side electrode on the GaN film.

Now just finished the construction of device architecture.With stretchable band the back side of wafer is pasted, be placed under the cutting machine again, so that wafer is cut into final chip size.This cutting technique will be cut and wear GaN rete and Ag metallic substrate layer, not wear stretchable band but do not cut.This cutting makes Ti-Al contact solder joint be positioned at the center of chip.The slice, thin piece of cutting is cleaned, so that remove the cutting chip, is stretched then and draws, so that separate still on tape each chip.The chip of finishing will break away from from stretchable band, just can be mounted with the mode that is same as conventional red LED, thereby produce ultra-thin blue led.

With 12V dc-battery source chip is tested.When battery is electrically connected to device, the emission blue light.Embodiment shown here is a kind of simple LED design, does not adopt any high-resolution and more most advanced and sophisticated equipment.For person skilled in the art, after reading the disclosure and related embodiment, can obtain many corrections and other embodiment.Therefore, it being understood that the present invention is not limited to disclosed specific embodiments, various corrections and other embodiment are believed to comprise within the scope of the appended claims.

Claims (49)

1. method of making at least one semiconductor device comprises:

Provide one to comprise lithium aluminate (LiAlO ₂) sacrificial growth substrate;

Contiguous sacrificial growth substrate forms the semiconductor layer that at least one comprises the III group-III nitride;

Substrate and sacrificial growth substrate will be installed to be fixed near described at least one semiconductor layer on the contrary; And

Remove sacrificial growth substrate.

2. according to the method for claim 1, also comprise at least one contact and installation substrate are joined on the surface of described at least one semiconductor layer on the contrary.

3. according to the method for claim 2, also comprise installation substrate and at least one semiconductor layer are divided into a plurality of individual semiconductor device.

4. according to the method for claim 3, comprise that also the installation substrate bonding with each individual semiconductor device arrives heat sink.

5. according to the method for claim 4, wherein, described heat sink copper (Cu) piece that comprises.

6. according to the process of claim 1 wherein, removing comprises carries out mechanical lapping and wet etching to sacrificial growth substrate.

7. according to the method for claim 6, wherein, described installation substrate moisture-resistant method is corroded.

8. according to the method for claim 6, also be included in and protect in the wet etching course to small part installation substrate.

9. according to the process of claim 1 wherein, described sacrificial growth substrate comprises monocrystalline LiAlO ₂

10. according to the process of claim 1 wherein, described at least one semiconductor layer comprises at least one mono-crystal gallium nitride (GaN) layer.

11. according to the process of claim 1 wherein, the fixed installation substrate comprises:

On described at least one semiconductor layer, form adhesive layer; And

Adhesive layer is bonded to the installation substrate.

12. according to the method for claim 11, wherein, described adhesive layer comprises at least a in (Au) of nickel (Ni) and gold.

13. method according to claim 11, wherein, described installation substrate comprises at least a in copper (Cu), silver (Ag), gold (Au), aluminium (Al), chromium (Cr), nickel (Ni), titanium (Ti), molybdenum (Mo), tungsten (W), zirconium (Zr), platinum (Pt), palladium (Pd), the silicon (Si).

14., form at least one semiconductor layer and comprise at least one semiconductor layer is mixed according to the process of claim 1 wherein.

15., also comprise the resilient coating that forms between sacrificial growth substrate and at least one semiconductor layer according to the method for claim 1; And, wherein remove sacrificial growth substrate and also comprise this resilient coating of removing.

16. according to the process of claim 1 wherein, described at least one semiconductor layer has m face (10 10) orientation.

17. according to the process of claim 1 wherein, the thickness of described at least one semiconductor layer is less than about 10 microns.

18. according to the process of claim 1 wherein, described at least one semiconductor layer be electrically biased luminous.

19. a method of making a plurality of semiconductor device comprises:

Provide one to comprise lithium aluminate (LiAlO ₂) sacrificial growth substrate;

Contiguous sacrificial growth substrate forms the semiconductor layer that at least one comprises the III group-III nitride;

Substrate and sacrificial growth substrate will be installed be fixed on the contrary near described at least one semiconductor layer, this installation substrate comprises at least a in metal and the silicon;

Adopt mechanical lapping and wet chemical etching technique method, remove sacrificial growth substrate;

On at least one semiconductor layer, form a plurality of the contact on the contrary with the installation substrate; And

Substrate and at least one semiconductor layer will be installed be divided into a plurality of individual semiconductor device.

20., comprise that also the installation substrate bonding with each individual semiconductor device arrives heat sink according to the method for claim 19.

21. according to the method for claim 19, wherein, described installation substrate moisture-resistant method corrosion.

22., also be included in and protect in the wet etching course to small part installation substrate according to the method for claim 19.

23. according to the method for claim 19, wherein, described sacrificial growth substrate comprises monocrystalline LiAlO ₂

24. according to the method for claim 19, wherein, described at least one semiconductor layer comprises at least one mono-crystal gallium nitride (GaN) layer.

25. according to the method for claim 19, wherein, the fixed installation substrate comprises:

On described at least one semiconductor layer, form adhesive layer; And

Adhesive layer is bonded to the installation substrate.

26., wherein, form at least one semiconductor layer and comprise described at least one semiconductor layer is mixed according to the method for claim 19.

27., also comprise the resilient coating that forms between sacrificial growth substrate and at least one semiconductor layer according to the method for claim 19; And, wherein remove sacrificial growth substrate and also comprise this resilient coating of removing.

28. according to the method for claim 19, wherein, described at least one semiconductor layer has m face (10 10) orientation.

29. according to the process of claim 1 wherein, described at least one semiconductor layer be electrically biased luminous.

30. a method of making at least one semiconductor device comprises:

Provide one to comprise monocrystalline lithium aluminate (LiAlO ₂) sacrificial growth substrate;

Contiguous sacrificial growth substrate forms at least one and comprises and have m face (10 10) semiconductor layer of Qu Xiang III group-III nitride;

Substrate and sacrificial growth substrate will be installed be fixed on the contrary near described at least one semiconductor layer, this installation substrate comprises at least a in metal and the silicon; And

Remove sacrificial growth substrate.

31. the method according to claim 30 also comprises:

At least one contact and installation substrate are joined on the surface of described at least one semiconductor layer on the contrary; And

Substrate and at least one semiconductor layer will be installed be divided into a plurality of individual semiconductor device; And

Arrive the installation substrate bonding of each individual semiconductor device heat sink.

32. according to the method for claim 31, wherein, removing comprises carries out mechanical lapping and wet etching to sacrificial growth substrate; And, the corrosion of substrate moisture-resistant method wherein is installed.

33. according to the method for claim 31, wherein, removing comprises carries out mechanical lapping and wet etching to sacrificial growth substrate; And be included in to protect in the wet etching course to small part substrate is installed.

34. according to the method for claim 31, wherein, described at least one semiconductor layer comprises at least one mono-crystal gallium nitride (GaN) layer.

35. according to the method for claim 31, wherein, the fixed installation substrate comprises:

On described at least one semiconductor layer, form adhesive layer; And

Adhesive layer is bonded to the installation substrate.

36., also comprise the resilient coating that forms between sacrificial growth substrate and at least one semiconductor layer according to the method for claim 31; And, wherein remove sacrificial growth substrate and also comprise this resilient coating of removing.

37. according to the method for claim 31, wherein, described at least one semiconductor layer be electrically biased luminous.

38. a semiconductor device comprises:

Heat sink;

Contiguous described heat sink installation substrate, described installation substrate comprise at least a in metal and the silicon;

With described heat sink opposite and determine that a plurality of semiconductor layers on the described installation substrate of at least one p-n junction, described semiconductor layer comprise and have m face (10 10) Qu Xiang monocrystalline III group iii nitride layer; And

, at least one contact in described semiconductor layer uppermost semiconductor layer on opposite with described installation substrate.

39. according to the semiconductor device of claim 38, wherein, described III group-III nitride comprises gallium nitride.

40., also comprise the adhesive layer between described installation substrate and the described semiconductor layer according to the semiconductor device of claim 38.

41. according to the semiconductor device of claim 40, wherein, described adhesive layer comprises at least a in (Au) of nickel (Ni) and gold.

42. according to the semiconductor device of claim 38, wherein, the described heat sink copper (Cu) that comprises.

43. semiconductor device according to claim 38, wherein, described installation substrate comprises at least a in copper (Cu), silver (Ag), gold (Au), aluminium (Al), chromium (Cr), nickel (Ni), titanium (Ti), molybdenum (Mo), tungsten (W), zirconium (Zr), platinum (Pt), palladium (Pd), the silicon (Si).

44. according to the semiconductor device of claim 38, wherein, described semiconductor layer is luminous in response to being applied to described metal substrate and described heat sink electrical bias.

45. a luminous semiconductor device comprises:

Heat sink;

Contiguous described heat sink metal substrate;

With described heat sink opposite and determine that a plurality of semiconductor layers on the described metal substrate of at least one p-n junction, described semiconductor layer comprise and have m face (10 10) nitride layer of Qu Xiang mono-crystal gallium nitride; And

, at least one contact in described semiconductor layer uppermost semiconductor layer on opposite with described metal substrate;

Described semiconductor layer is in response to being applied to described substrate with described at least one electrical bias that contacts and luminous.

46., also comprise the adhesive layer between described metal substrate and the described semiconductor layer according to the luminous semiconductor device of claim 45.

47. according to the luminous semiconductor device of claim 46, wherein, described adhesive layer comprises at least a in (Au) of nickel (Ni) and gold.

48. according to the luminous semiconductor device of claim 45, wherein, the described heat sink copper (Cu) that comprises.

49. luminous semiconductor device according to claim 45, wherein, described metal substrate comprises at least a in copper (Cu), silver (Ag), gold (Au), aluminium (Al), chromium (Cr), nickel (Ni), titanium (Ti), molybdenum (Mo), tungsten (W), zirconium (Zr), platinum (Pt), palladium (Pd), the silicon (Si).

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