Method for producing a first contact layer and a second contact layer on a power semiconductor body, and power semiconductor device

Abstract

A method for producing a first contact layer (5) and a second contact layer (6) on a power semiconductor body (2) is specified, comprising: - providing the power semiconductor body (2), comprising a substrate region (3) with a bottom surface and an epitaxial body region (4) with a top surface facing away from the bottom surface, - applying a first layer on the top surface and app lying a second layer on the bottom surface, wherein the fir st layer comprises a first material comprising titanium, - incorporating a further material into the first layer, wherein the further material comprises phosphorus, and - annealing the power semiconductor body (2) with the first layer comprising the further material and the second layer for a predetermined time interval at a predetermine d annealing temperature, such that the first layer and the further material form the first contact layer (5) being a titanium-phosphorus alloy and the second layer form s a second contact layer (6). Furthermore, a power semiconductor device (1) is specified.

Description

[0001] P2024,0808 WO N / P240062WO01 June 25,2025 -1 - Description METHOD FOR PRODUCING A FIRST CONTACT LAYER AND A SECOND CONTACT LAYER ON A POWER SEMICONDUCTOR BODY,AND PWOER SEMICONDUCTOR DEVICEThe present disclosure relates to a method for prod ucing afirst contact layer and a second contact layer on a powersemiconductor body, and to a power semiconductor de vice.Typically,fora metallization on a typicalpowersemiconductor body a two-step process is performed, whereinan ohmic contact is deposited, being followed by de positing adifferent metal in order to obtain a Schottky conta ct.An objective of the disclosure is to provide a meth od bymeans ofwhich contactscan be produced on a powersemiconductor body particularly efficiently. A furt herembodimentrelatesto a powersemiconductordevice having such contacts.This is achieved by the subject-matter of the indep endentclaims. Further embodiments are evident from the de pendentclaimsand the following description. The method forproducing a firstcontactlayerand a secondcontact layer on a power semiconductor body is desc ribed. Theterm “power”here and in the following refers,for example,to power semiconductor chips particularly comprised by apower electronic component adapted for processing v oltagesand currents of more than 100 V and / or more than 10 A,exemplarilyvoltagesofup to 10 kV and electrical currents ofup to 10 kA. P2024,0808 WO N / P240062WO01 June 25,2025 -2 -The power semiconductor body is, for example, a cor estructure of a power semiconductor device. Exemplar ily, thepower semiconductor device comprising the power sem iconductorbody is at least one of a Schottky diode, a bipolar junctiontransistor, BJT, a power junction field-effect tran sistor,JFET, a power metal-oxide-semiconductor field-effec ttransistor, MOSFET. The power semiconductor body co mprises orconsistsofa wide-bandgap semiconductormaterial, for example.Exemplarily, the first contact layer and the second contactlayer are each configured to be contactable externa lly.Further, the first contact layer and the second con tact layerare in particular configured to provide a current t o thepower semiconductor body. The first contact layer a nd thesecond contactlayereach comprise orconsistofa metal,for example.According to an embodiment of the method, the powersemiconductor body is provided, comprising a substr ate regionwith a bottom surface and an epitaxialbodyregion with a topsurface facing away from the bottom surface. Exempl arily, thepower semiconductor body has a main extension plane extendingin lateral directions. A vertical direction is orie ntedperpendicular to the lateral directions. In particu lar, thesubstrate region and the epitaxial body region each have amain extension plane extending in lateral direction s.Exemplarily, the substrate region and the epitaxial bodyregion are stacked above one another, along the ver ticaldirection. P2024,0808 WO N / P240062WO01 June 25,2025 -3 -The substrate region has, for example, the bottom s urface anda top surface being connected byatleastone side surface.The epitaxial body region has, for example, a botto m surfaceand the top surface being connected by at least one sidesurface. The top surface of the substrate is partic ularly indirect contact with the bottom surface of the epita xial bodyregion. In particular, the bottom surface of the su bstrateregion and the top surface of the epitaxial body re gion arefreelyaccessible when provided.A thickness in the vertical direction of the substr ate regionis larger by at least one order of magnitude than a thicknessin the vertical direction of the epitaxial body reg ion.Exemplarily,the thicknessofthe substrate region isat least100 μm oratleast300 μm and / oratmost800 μm oratmost 500 μm. Exemplarily, the thickness of the epitaxial bodyregion isatleast1 μm oratleast5 μm and / oratmost50 μm oratmost30 μm.For example, the epitaxial body region is epitaxial ly grownon the substrate region. In particular, the substra te regionis a growth substrate for the epitaxial body region . Inparticular, the substrate region provides a mechani calsupport for the epitaxial body region. Exemplarily, a defectdensityofthe epitaxialbodyregion issmallerby atleastone order of magnitude than a defect density of the substrateregion.Exemplarily, the substrate region comprises at leas t onedopant of a first type with a maximal first concent ration.For example, the first type is characteristic of an n-type.Exemplarily, the epitaxial body region comprises at least onedopant of the first type with a maximal second conc entration. P2024,0808 WO N / P240062WO01 June 25,2025 -4 -For example, the maximal first concentration is lar ger by atleast one order of magnitude than the maximal secon dconcentration.In particular,the substrate regioncorresponds to an n +-doped substrate region, and at least apart of the epitaxial body region corresponds to an n - -dopedepitaxial body region, forming particularly a drift layer.Exemplarily, the epitaxial body region comprises at least onedopant of a second type in a well region. For examp le, thefirsttype ischaracteristicofa p-type.The well regionextends, for example, from the top side of the epit axial bodyregion up to a predetermined depth in the drift lay er.Exemplarily, the epitaxial body region comprises at least onefurther dopant of the first type in a contact regio n with amaximal further first concentration. The contact re gionextends, for example, from the top side of the epit axial bodyregion in the well region up to a predetermined dep th in thewell region. In particular, the predetermined depth of thewellregion islargerthan the predetermined depth ofthe contactregion.The contactregion isparticularly embeddedin the well region and / or the well region is partic ularlyembedded in the drift layer. Exemplarily, top surfa ces of thecontact region and / or the well region are part of t he topsurface ofthe epitaxialbodyregion.For example, the further dopant of the first type i s equal tothe dopant of the first type, and the maximal firstconcentration is equal to or higher than at least 5 0% thanthe maximal further first concentration. In particu lar, thecontact region corresponds to an n +-doped contact region. P2024,0808 WO N / P240062WO01 June 25,2025 -5 - According to the embodimentofthe method,a first layerisapplied on the top surface and a second layer is ap plied onthe bottom surface, wherein the first layer compris es a firstmaterial comprising titanium. The first layer and t he secondlayerare each in particulara metalliclayer.The secondlayer comprises a second material. The first materi al can bethe same asordifferentfrom the second material. A thicknessin the verticaldirection ofthe first layeris,for example, at least 10 nm or at least 30 nm and / o r at most100 nm or at most 80 nm, such as approximately 60 n m or 70nm.Exemplarily, the first layer comprises the first ma terialwith a purity of at least 99%, particularly at leas t 99.99%.In particular, the first layer exclusively consists oftitanium. “Exclusively consists” means here that th e firstlayer comprises solely titanium with a purity of at least99%, particularly at least 99.99%. Due to productio ntolerances, other substances can be comprised by th e firstlayerbyatmost1% oratmost0.01%.According to the embodiment of the method, a furthe r materialis incorporated into the first layer, wherein the f urthermaterial comprises phosphorus. Exemplarily, the fur thermaterialisincorporated into the firstlayerdown to apredetermined depth in the first layer. The predete rmineddepth extends, for example, from a top surface of t he firstlayer in the vertical direction towards the epitaxi al bodyregion. The predetermined depth is, for example, at least 50%or at least 70% and / or at most 95% or at most 90% o f thethicknessofthe firstlayer.Alternatively,the P2024,0808 WO N / P240062WO01 June 25,2025 -6 -predetermined depth equals the complete thickness o f thefirstlayer.According to the embodiment of the method, the powe rsemiconductorbodywith the firstlayercomprising thefurther material and the second layer is annealed f or apredetermined time interval at a predetermined anne alingtemperature, such that the first layer and the furt hermaterial form the first contact layer being a titan ium-phosphorus alloy and the second layer forms a secon d contactlayer. In particular, the titanium-phosphorus alloy is formedof the first material and the further material duri ng theannealing step. Exemplarily, the first contact laye rcorresponds geometrically to the first layer. For e xample,the second contactlayercorrespondsgeometrically to the second layer.For example, the first contact layer comprises or c onsists ofthe titanium-phosphorus alloy. In particular, due t o theannealing, the first material and the further mater ial arehomogeneously distributed in the first contact laye r.In particular,an electricalcontactpropertyofa firsttypeof the first contact layer is different from an ele ctricalcontact property of a second type of the second con tactlayer. Exemplarily, the electrical contact property of thefirst type of the first contact is characteristic o f aSchottky contact and the electrical contact propert y of thesecond type of the second contact is characteristic of anohmic contact after annealing the power semiconduct or bodywith the firstlayerwith the furthermaterialand the second layer. P2024,0808 WO N / P240062WO01 June 25,2025 -7 -In sum, two contacts having different electrical co ntactpropertieswith respectto the powersemiconductor bodycanbe produced by the method advantageously simultaneo usly.According to a furtherembodimentofthe method,a first interface between the epitaxialbodyand the first contactlayer is formed of a Schottky contact, and a second interfacebetween the substrate and the second contactlayer isformedof an ohmic contact. Advantageously, the Schottky c ontact andthe ohmic contact are producible in a single method step.According to a furtherembodimentofthe method,a barrierheight of the first contact layer is higher by at l east 50%than a barrierheightofthe second contactlayer.Exemplarily, a barrier height of the first layer co mprisingthe firstmaterialissmallerbyatleast50% than a barrierheight of the first contact layer. In particular, t hetitanium-phosphorus alloy has the increased barrier height incomparison to the first layer comprising the titani um.Advantageously, the formation of the titanium-phosp horusalloy allows the increase of the respective barrier height ofthe Schottkycontactin contrastto titanium.Exemplarily, the barrier height of the first contac t layerwith the first material is approximately 0.9 eV, an d thebarrierheightofthe titanium-phosphorusalloyisapproximately 1.9 eV. The introduction of phosphoru s in thetitanium, for alloy formation, is beneficial in ter ms ofleakage current. In particular, such an alloy forma tionadvantageouslyleadsto a higherbarrierheightas wellastoa lower leakage current in power semiconductor devi ces. P2024,0808 WO N / P240062WO01 June 25,2025 -8 -According to a further embodiment of the method, th e furthermaterial is incorporated in the first layer by usin g a plasmacomprising the further material. The further materi al is, inparticular,incorporated byplasma-immersion ion implantation.Exemplarily, the plasma is a diphosphorus P 2 plasma. Aconcentration of the further material in the plasma is atleast 10 14 cm -2 and / or at most 10 18 cm -2. Exemplarily, thepowersemiconductorbodyisbiased with a negative voltage of atleast5 kV and / oratmost10 kV,forimplanting the furthermaterialin the firstlayer.According to a further embodiment of the method, th e furthermaterial is incorporated in the first layer by usin g lowenergy implantation. Exemplarily, phosphorus ions a reaccelerated towards the power semiconductor body, e .g. withat least 5 keV and / or at most 50 keV, for implantin g thefurther material in the first layer. A concentratio n of thephosphorus ions is at least 10 14 cm -2 and / or at most 10 18 cm -2.According to a further embodiment of the method, th e firstlayer is applied onto at least one partial region o f the topsurface. Exemplarily, the first material is, for ex ample,applied to the partial region on the top surface of theepitaxial body region. Exemplarily, the top surface of theepitaxial body region is free of the first material in placeswhere the first material is not applied to the part ialregion.For example, the first material is applied to the p artialregion on the top surface of the epitaxial body reg ion via amask.In particular,the firstmaterialisapplied such that P2024,0808 WO N / P240062WO01 June 25,2025 -9 -the first material is in direct contact with the dr ift layer,the wellregion and / orthe contactregion.The second material is, for example, applied to a r egion onthe bottom surface of the substrate region. For exa mple, thesecond material is applied on the bottom surface of thesubstrate region such that the second material cove rs atleast 80%, or at least 90% of the bottom surface, e xemplarilycompletely covers the bottom surface of the substra te region.The first material and / or the second material is ex emplarilyapplied by a physical vapor deposition method, such assputtering and / orthermalevaporation.According to a further embodiment of the method, th e furthermaterial is applied only onto the first layer by us ing amask.In particular,the maskpreventsthe further materialfrom being incorporated in the semiconductor materi al of thepowersemiconductorbodyin placeswhere the first layeris notarranged.According to a further embodiment of the method, th e furthermaterial is applied onto the first layer and onto r egions ofthe top surface notcovered bythe firstlayer.Inparticular, the further material is also incorporat ed in thesemiconductor material of the power semiconductor b ody inplaces where the first layer is not arranged. Exemp larily,the further material is incorporated in the drift r egion,particularlythe top surface thereof.Advantageously, when using the further material, e. g.phosphorus, this has particularly no substantial im pact on aresistivity of the power semiconductor body. P2024,0808 WO N / P240062WO01 June 25,2025 -10 -Additionally, using the further material, e.g. phos phorus, atthe top surface ofthe powersemiconductorbodyadvantageously leads to a diffusion of carbon inter stitialsthat, occupying empty C sites, lead to the annihila tion ofcarbon vacancies, VC. Thus, advantageously, by appl ying thefurther material on the power semiconductor body, c arbonvacancies in the power semiconductor body can be re duced, andthus, a leakage current is reduced as well in powersemiconductor devices .According to a further embodiment of the method, th e secondlayer comprises a second material comprising titani um and / ornickel.Exemplarily, the second material is exclusively for med of thefirst material. When the second material is exclusi velyformed of the first material, the first layer and t he secondlayer consist of the same material, namely titanium .Alternatively, the second material comprises or con sists ofnickel or a bilayer comprising a first sublayer com prising orconsisting of titanium and a second sublayer compri sing orconsisting ofnickel.Advantageously, by using titanium and / or nickel, th e ohmiccontactisproduced during annealing.According to a further embodiment of the method, th epredetermined time interval is at least 1 minute an d at most10 minutes. P2024,0808 WO N / P240062WO01 June 25,2025 -11 -According to a further embodiment of the method, th epredetermined annealing temperature is at least 900 °C and atmost1100°C. Byusing such a predetermined time intervaland / or such apredetermined annealing temperature, the Schottky c ontact aswell as the ohmic contact is advantageously produce d. Inaddition, when the further material is also arrange d on thepowersemiconductorbody,the temperature range of the predetermined annealing temperature advantageously doesnot lead to an n+ formation,because forthisatleast 1600°C are needed.According to a further embodiment of the method, th e powersemiconductor body is based on silicon carbide or g alliumnitride.A further embodiment relates to a power semiconduct or device,in particularcomprising a firstcontactlayerand a secondcontact layer being produced or being producible by themethod as described herein above. Therefore, the fe atures asdescribed in connection with the power semiconducto r deviceare also applicable to the method and vice versa.According to an embodiment, the power semiconductor devicecomprises a power semiconductor body comprising a s ubstrateregion with a bottom surface and an epitaxialbody regionwith a top surface facing away from the bottom surf ace.According to the embodiment, the power semiconducto r devicecomprises a first contact layer arranged on the top surface. P2024,0808 WO N / P240062WO01 June 25,2025 -12 -According to the embodiment, the power semiconducto r devicecomprises a second contact layer arranged on the bo ttomsurface.According to the embodiment of the power semiconduc tordevice, the first contact layer comprises a titaniu m-phosphorusalloy. Advantageously,with such a firstcontactlayer,a Schottky contactisprovided,which effectivelyreducesthe leakage currentin powersemiconductordevicescompared to titanium contactlayers.According to the embodiment of the power semiconduc tordevice, the epitaxial body region comprises an n-ty pe dopedregion.According to the embodiment of the power semiconduc tordevice, the n-type doped region and the first conta ct layerare in directcontactwith one anotherforforming a firstinterface. In particular, the first interface betwe en theepitaxial body and the first contact layer is forme d of aSchottkycontact.According to the embodiment of the power semiconduc tordevice, the power semiconductor body is based on si liconcarbide ofa 4H polytype ora 6H polytype. In particular,the designation "4H"indicatesthat thecorresponding polytype is a hexagonal polytype char acteristicofa hexagonalcrystalstructure.The hexagonal4H polytypehas, in particular, a periodicity of 4 in a stackin g sequencealong a c-axis of a hexagonal unit cell. This means that the P2024,0808 WO N / P240062WO01 June 25,2025 -13 -silicon carbide having the hexagonal 4H polytype ha s arepeating sequence every four bilayers of silicon a nd carbonatoms. In particular,the designation "6H"indicatesthat thecorresponding polytype is a hexagonal polytype char acteristicofa hexagonalcrystalstructure.The hexagonal6H polytypehas, in particular, a periodicity of 6 in a stackin g sequencealong a c-axis of a hexagonal unit cell. This means that thesilicon carbide having the hexagonal 46 polytype ha s arepeating sequence everysixth bilayersofsilicon and carbon atoms.According to the embodiment of the power semiconduc tordevice, the power semiconductor body is based on ga lliumnitride. The accompanying Figuresare included to provide a furtherunderstanding. In the Figures, elements of the same structureand / orfunctionalitymaybe referenced bythe same reference signs.Itisto be understood thatthe embodiments shown inthe Figures are illustrative representations and ar e notnecessarilydrawn to scale.Figure 1 shows a flow chart of the method according to anexemplaryembodiment.Figures 2, 3 and 4 each shows a schematic view of a powersemiconductor device according to an exemplary embo diment.Figure 5 shows a schematic view of a power semicond uctordevice being a Schottky diode according to an exemp laryembodiment. P2024,0808 WO N / P240062WO01 June 25,2025 -14 -Figures 6 and 7 each shows a simulated diagram of a powersemiconductor device according to an exemplary embo diment.Figure 8 shows a schematic view of a power semicond uctordevice being a MOSFET according to an exemplary emb odiment.Figure 9 shows a simulated diagram of a power semic onductordevice according to an exemplaryembodiment.In the method stage S1 according to the exemplary e mbodimentof Figure 1, a power semiconductor body 2 is provid ed,comprising a substrate region 3 with a bottom surfa ce and anepitaxial body region 4 with a top surface facing a way fromthe bottom surface. Subsequently,in method stage S2,a firstlayeris applied onthe top surface and a second layer is applied on th e bottomsurface,wherein the firstlayercomprisesa first material comprising titanium.In method stage S4, a further material is incorpora ted intothe first layer, wherein the further material compr isesphosphorus.Subsequently, in method stage S4, the power semicon ductorbody2 with the firstlayercomprising the further materialand the second layer is annealed for a predetermine d timeintervalata predetermined annealing temperature, such thatthe first layer and the further material form the f irstcontact layer 5 being a titanium-phosphorus alloy a nd thesecond layerformsa second contactlayer6. P2024,0808 WO N / P240062WO01 June 25,2025 -15 -In particular, the power semiconductor body 2 can b epreprocessed before applying the first and / or the s econdcontact layer 6. The preprocessing involves the gen eration ofspecific doped regions in the power semiconductor b ody 2.The power semiconductor device 1 according to Figur e 2comprises the power semiconductor body 2 with the f irstcontact layer 5 and the second contact layer 6, bei ng inparticular produced by the method described in conn ectionwith Figure 1. The power semiconductor body 2 compr ises thesubstrate region 3 and the epitaxial body region 4, which arestacked above one another along a stacking directio n beingparticularlyparallelto a verticaldirection.The verticaldirection is perpendicular to the main extension pl anes ofthe substrate region 3 and the epitaxial body regio n 4.The substrate region 3 comprises at least one dopan t of afirst type with a predetermined maximal first conce ntration,wherein the firsttype isan n-type.The epitaxial bodyregion 4 comprises at least one dopant of the first type witha predetermined maximalsecond concentration.Thepredetermined maximal first concentration is larger by atleast one order of magnitude than the predetermined maximalsecond concentration.An n +-doped substrate region 3 of the power semiconducto rdevice 1 correspondsparticularlyto the substrate region 3. A driftlayerofthe powersemiconductordevice 1,particularly an n - -doped epitaxial body region 4, correspondsto atleasta partofthe epitaxialbodyregion 4.The first contact layer 5 is in direct contact with theepitaxial body region 4, particularly the drift lay er being P2024,0808 WO N / P240062WO01 June 25,2025 -16 -the n - -doped epitaxial body region 4. In this region, a f irstinterface between the epitaxialbodyand the first contactlayer 5 is formed of a Schottky contact. A second i nterfacebetween the substrate and the second contactlayer 6 is formed ofan ohmiccontact,wherein both different functionalcontacts are formed in the single annealing step ac cording toFigure 1.The power semiconductor device 1 according to Figur e 3 is ais a Schottky diode comprising the n +-doped substrate region3 and the n - -doped epitaxial body region 4. The n +-dopedsubstrate region 3 has a maximal first concentratio n of adopant of a first type being approximately 10 18 cm -3 and then- -doped epitaxial body region 4 has a maximal secondconcentration ofa dopantofthe firsttype beingapproximately 10 16 cm -3.Further, the power semiconductor body 2 comprises a t leastone further dopant of a second type in a further re gion 12,which is embedded in epitaxial body region 4. The f urtherregion 12 is particularly a p +-doped further region 12. Thep+-doped further region 12 has a maximal third concen trationof a dopant of the second type being at least 10 14 cm -3 and atmost 10 16 cm -3.The first contact layer 5 is arranged above the pow ersemiconductor body 2 being at least regionally in d irectcontact to the n - -doped epitaxial body region 4 and the p +-doped further region 12. An oxide layer 13 is arran ged, atleast regionally, between the power semiconductor b ody 2 andthe firstcontactlayer5. P2024,0808 WO N / P240062WO01 June 25,2025 -17 -The power semiconductor device 1 according to Figur e 4 is aMOSFET, wherein a structured oxide 13 layer is arra nged inregionsbetween the powersemiconductorbody2 and the first contactlayer5.The power semiconductor device 1 according to Figur e 5 is aSchottky diode. For such a Schottky diode, a curren t voltagecharacteristic is simulated for different barrier h eights ofthe first contact layer 5, as shown in connection w ithFigures6 and 7.On the y axis of Figures 6 and 7, a current I in A / cm2 isindicated and on the xaxisofFigure 6,a forward voltage Vforwardin V isindicated and on the xaxisofFigure 7,areverse voltage V reverse in V is indicated. The upper curve ischaracteristic of a comparatively low barrier heigh t and thelower curve is characteristic of a comparatively hi gh barrierheight. Advantageously, by increasing the barrier h eight,improved forward and blocking voltage characteristi cs can beachieved. In particular, an improved on-state resis tance andlower leakage current are achieved by increasing th e barrierheight, i.e. with a titanium phosphorus alloy for t he firstcontactlayer5.The power semiconductor device 1 according to Figur e 8 is aMOSFET. The epitaxial body region 4 comprises at le ast onedopant of a second type in a well region 7, which i sdifferent from the first type. The well region 7 is embeddedin the driftlayer.In particular,the wellregion 7 isa p-well region. Further, the epitaxial body region 4 c omprisesatleastone furtherdopantofthe firsttype in a contactregion 8, which is embedded in the well region 7. A gate 9comprising a gate metal10 and a gate oxide 11 are provided P2024,0808 WO N / P240062WO01 June 25,2025 -18 - partlyon the contactregion 8,the wellregion 7, and thedrift region arranged next to the contact region 8.Further, the epitaxial body region 4 comprises at l east onefurther dopant of the second type in a further regi on 12,which isembedded in the wellregion 7 and located adjacent to the contactregion 8.The first contact layer 5 is in direct contact with thecontact region 8, the further region 12 and the dri ft layer.Advantageously, when forming the first contact laye r 5 at thetop surface,simultaneouslya Schottkycontactand ohmiccontact formation is achieved, allowing for bipolardegradation avoidance while preserving blocking per formance.Particularly, the first interface between the first contactlayer 5 and the contact region 8 and / or the drift l ayer ischaracteristic of the Schottky contact, and a furth er firstinterface between the first contact layer 5 and the wellregion 7 ischaracteristicofthe ohmiccontact.For such a MOSFET, a current voltage characteristic issimulated for different barrier heights of the firs t contactlayer5,asshown in connection with Figure 9.On the y axis of Figure 9, a current I in A / cm 2 is indicatedand on the x axis of Figure 9, a reverse voltage V reverse in Visindicated.The uppercurve ischaracteristicof acomparatively low barrier height and the lower curv e ischaracteristic of a comparatively high barrier heig ht. Aleakage current is smaller by about two orders of m agnitudefor the lower curve corresponding to the first cont act layer5 comprising the titanium phosphorusalloy. P2024,0808 WO N / P240062WO01 June 25,2025 -19 -The exemplary embodiments, in particular features o f theexemplary embodiments, of the Figures can be combin ed withone another.

[0002] P2024,0808 WO N / P240062WO01 June 25,2025 -20 - Reference Signs 1 powersemiconductordevice 2 powersemiconductorbody 3 substrate region 4 epitaxialbodyregion 5 firstcontactlayer 6 second contactlayer 7 wellregion 8 contactregion 9 gate 10 gate metal 11 gate oxide 12 furtherregion 13 oxide layer S1..S4 method stages

Claims

P2024,0808 WO N / P240062WO01 June 25,2025 -21 - Claims1. Method for producing a first contact layer (5) a nd asecond contact layer (6) on a power semiconductor b ody (2),comprising:- providing the power semiconductor body (2), compr ising asubstrate region (3) with a bottom surface and an e pitaxialbody region (4) with a top surface facing away from thebottom surface,- applying a first layer on the top surface and app lying asecond layer on the bottom surface, wherein the fir st layercomprisesa firstmaterialcomprising titanium,- incorporating a further material into the first l ayer,wherein the furthermaterialcomprisesphosphorus, and- annealing the power semiconductor body (2) with t he firstlayer comprising the further material and the secon d layerfor a predetermined time interval at a predetermine dannealing temperature, such that the first layer an d thefurther material form the first contact layer (5) b eing atitanium-phosphorus alloy and the second layer form s a secondcontactlayer(6). 2.Method according to claim 1,wherein -a firstinterface between the epitaxialbodyand the first contactlayer(5)isformed ofa Schottkycontact, and asecond interface between the substrate and the seco nd contactlayer(6)isformed ofan ohmiccontact. 3.Method according to claim 1 or2,wherein- a barrier height of the first contact layer (5) i s higherby at least 50% than a barrier height of the second contactlayer(6).P2024,0808 WO N / P240062WO01 June 25,2025 -22 -4. Method according to any one of claims 1 to 3, wh erein- the further material is incorporated in the first layer byusing a plasma comprising the furthermaterial.

5. Method according to any one of claims 1 to 3, wh erein- the further material is incorporated in the first layer byusing low energyimplantation.

6. Method according to any one of claims 1 to 5, wh erein- the first layer is applied onto at least one part ial regionofthe top surface.

7. Method according to any one of claims 1 to 6, wh erein- the further material is applied only onto the fir st layerbyusing a mask.

8. Method according to any one of claims 1 to 6, wh erein- the further material is applied onto the first la yer andonto regionsofthe top surface notcovered bythe first layer.

9. Method according to any one of claims 1 to 8, wh erein- the second layer comprises a second material comp risingtitanium and / ornickel.

10. Method according to any one of claims 1 to 9, w herein- the predetermined time interval is at least 1 min ute and atmost10 minutes. 11.Method according to anyone ofclaims1 to 10, wherein- the predetermined annealing temperature is at lea st 900°Cand atmost1100°C.P2024,0808 WO N / P240062WO01 June 25,2025 -23 - 12.Method according to anyone ofclaims1 to 11, wherein- the power semiconductor body (2) is based on sili concarbide orgallium nitride. 13.Powersemiconductordevice (1),comprising- a power semiconductor body (2) comprising a subst rateregion (3) with a bottom surface and an epitaxial b ody region(4)with a top surface facing awayfrom the bottom surface,- a first contact layer (5) arranged on the top sur face, and- a second contact layer (6) arranged on the bottom surface,wherein- the first contact layer (5) comprises a titanium- phosphorusalloy.

14. Power semiconductor device (1) according to cla im 13,wherein- the epitaxial body region (4) comprises an n-type dopedregion,and- the n-type doped region and the first contact lay er (5) arein direct contact with one another for forming a fi rstinterface.

15. Power semiconductor device (1) according to cla im 14,wherein- the power semiconductor body (2) is based on sili concarbide ofa 4H polytype ora 6H polytype,or- the power semiconductor body (2) is based on gall iumnitride.

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