Radiation emitting semiconductor device and method for manufacturing the device

Abstract

A radiation emitting semiconductor device (10) comprises a first semiconductor layer (110) of a first conductivity type arranged over an active zone (115), and a first contact element (130) arranged over a first main surface (111) of the first semiconductor layer (110). Electromagnetic radiation (15) generated in the active zone (15) is emitted via the first main surface (111). The first contact element (130) extends along a first direction. The radiation emitting semiconductor device (10) further comprises a trench (132) adjacent to the first contact element (130) and extending in the first direction. The trench (132) is formed in the first main surface (111) of the first semiconductor layer (110).

Description

[0001] RADIATION EMITTING SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE DEVICE

[0002] For InGaAlP and InGaAs based red and infrared radiation emitting device architectures are employed comprising a front metal contact . Generally, attempts are being made in order to increase the ef ficiency of these radiation emitting devices .

[0003] It is an obj ect of the present invention to provide an improved radiation emitting semiconductor device and an improved method for manufacturing the device .

[0004] SUMMARY

[0005] According to embodiments , the above obj ect is achieved by the claimed matter according to the independent claims . Further developments are defined in the dependent claims .

[0006] According to embodiments , a radiation emitting semiconductor device comprises a first semiconductor layer of a first conductivity type arranged over an active zone , and a first contact element arranged over a first main surface of the first semiconductor layer . Electromagnetic radiation generated in the active zone is emitted via the first main surface . The first contact element extends along a first direction . The radiation emitting semiconductor device further comprises a trench adj acent to the first contact element and extending in the first direction, the trench being formed in the first main surface of the first semiconductor layer .

[0007] For example , the first main surface may be textured . Texture elements of the texture may extend to a height a from a base portion of the texture element to a first main surface of the first semiconductor layer having a maximum height . A depth f of the trench is larger than the height a of the texture , the depth f being measured with respect to the first main surface of the first semiconductor layer having the maximum height .

[0008] According to embodiments , a distance 1 between adj acent texture elements may be smaller than a length t of the trench measured in the first direction .

[0009] For example , the trench may extend along the first contact element .

[0010] According to embodiments , a bottom side of the first contact element may be directly adj acent to a bottom side of the trench .

[0011] The radiation emitting semiconductor device may further comprise a current spreading layer of the first conductivity type adj acent to a bottom side of the first contact element . The current spreading layer may have a doping concentration di f ferent from, e . g . higher than a doping concentration of the first semiconductor layer or may have a composition di f ferent from a composition of the first semiconductor layer . According to further embodiments , additional layers , e . g . an electrical contact layer e . g . having a higher doping concentration than the first semiconductor layer may be arranged between the first contact element and the current spreading layer .

[0012] According to further embodiments , the radiation emitting semiconductor device may further comprise a pedestal between a bottom side of the trench and a bottom side of the first contact element .

[0013] For example , the bottom side of the first contact element may be arranged above a base portion of the texture elements . According to embodiments , an upper surface of the first contact element may be arranged above the first main surface of the first semiconductor layer .

[0014] For example , the radiation emitting semiconductor device may further comprise an electrical contact layer of the first conductivity type directly adj acent to a bottom side of the first contact element . The electrical contact layer may have a doping concentration di f ferent from, e . g . higher than a doping concentration of the first semiconductor layer or may have a composition di f ferent from a composition of the first semiconductor layer .

[0015] By way of example , the first semiconductor layer may comprise InxGayAli-x-yP, InxGai-xAs , AlxGai-xAs , InxAlyGai-x-yAszPi-z, wherein 0 dx, y, z<l .

[0016] According to embodiments , a method of manufacturing a radiation emitting semiconductor device may comprise forming a photoresist layer over a semiconductor layer stack and patterning the photoresist layer in accordance with a surface texture to be formed in a first main surface of a first semiconductor layer of the semiconductor layer stack comprising removing a portion of the patterned photoresist layer in a first region of a first contact element . The method further comprises etching the first semiconductor layer in exposed portions and forming a first contact element in the first region .

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this speci fication . The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principles . Other embodiments of the invention and many of the intended advantages will be readily appreciated, as they become better understood by reference to the following detailed description . The elements of the drawings are not necessarily to scale relative to each other . Like reference numbers designate corresponding similar parts .

[0019] Fig . 1 is a perspective view of a radiation emitting semiconductor device according to embodiments .

[0020] Fig . 2A shows a further perspective view of portions of a radiation emitting semiconductor device according to embodiments .

[0021] Fig . 2B is a cross-sectional view of a portion of the radiation emitting semiconductor device shown in Fig . 2A.

[0022] Fig . 2C is a cross-sectional view of a portion of a radiation emitting semiconductor device according to further embodiments .

[0023] Fig . 3A is a perspective view of a portion of a radiation emitting semiconductor device according to further embodiments .

[0024] Fig . 3B is a cross-sectional view of a portion of a radiation emitting semiconductor device shown in Fig . 3A.

[0025] Fig . 3C is a further cross-sectional view of a portion of a radiation emitting semiconductor device shown in Fig . 3A. Fig. 4A is a perspective view of a portion of a radiation emitting semiconductor device according to further embodiments .

[0026] Fig. 4B is a cross-sectional view of a portion of a radiation emitting semiconductor device shown in Fig. 4A.

[0027] Fig. 4C is a cross-sectional view of a portion of a radiation emitting semiconductor device according to further embodiments .

[0028] Fig. 4D is a further cross-sectional view of a portion of a radiation emitting semiconductor device shown in Fig. 4A.

[0029] Figs. 5A to 5D are cross-sectional views of a workpiece when performing a method of manufacturing a radiation emitting semiconductor device according to embodiments.

[0030] Fig. 6 summarizes the method according to embodiments.

[0031] DETAILED DESCRIPTION

[0032] In the following detailed description reference is made to the accompanying drawings, which form a part hereof and in which are illustrated by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology such as "top", "bottom", "front", "back", "over", "on", "above", "leading", "trailing" etc. is used with reference to the orientation of the Figures being described. Since components of embodiments of the invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope defined by the claims .

[0033] The description of the embodiments is not limiting . In particular, elements of the embodiments described hereinafter may be combined with elements of di f ferent embodiments .

[0034] The terms "wafer" or " semiconductor substrate" used in the following description may include any semiconductor-based structure that has a semiconductor surface . Wafer and structure are to be understood to include doped and undoped semiconductors , epitaxial semiconductor layers , e . g . supported by a base semiconductor foundation, and other semiconductor structures . For example , a layer of a first semiconductor material may be grown on a growth substrate of a second semiconductor material . According to further embodiments , the growth substrate may be an insulating substrate such as a sapphire substrate . Depending on the purpose of use , the semiconductor may be based on a semiconductor material having a direct or an indirect bandgap . Examples of semiconductor materials particularly suitable for generation of electromagnetic radiation comprise nitride-compound semiconductors , by which e . g . ultraviolet or blue light or longer wavelength light may be generated, such as GaN, InGaN, AIN, AlGaN, AlGalnN, phosphide-compound semiconductors , by which e . g . green or longer wavelength light may be generated such as GaAsP, AlGalnP, GaP, AlGaP, as well as further semiconductor materials including AlGaAs , SiC, ZnSe , GaAs , ZnO, Ga203, diamond, hexagonal BN und combinations of these materials . Further examples of semiconductor materials may as well be silicon, silicon-germanium and germanium . The stoichiometric ratio of the compound semiconductor materials may vary . In the context of the present speci fication, the term " semiconductor" further encompasses organic semiconductor materials .

[0035] The term " substrate" generally refers to semiconductor substrates , conductive or insulating substrates .

[0036] The terms " lateral" and "hori zontal" as used in thi s speci fication intends to describe an orientation parallel to a first surface of a substrate or semiconductor body . This can be for instance the surface of a wafer or a die .

[0037] The term "vertical" as used in this speci fication intends to describe an orientation which is arranged perpendicular to the first surface of a substrate or semiconductor body .

[0038] Within the present disclosure , the term "trench" may refer to a recess or notch . For example , the trench may be filled with a filling material having a refractive index which is considerably smaller than the refractive index of the adj acent semiconductor material . For example , a refractive index contrast between the epitaxially grown semiconductor material and the filling material may induce reflection and / or backward-scattering of light .

[0039] Fig . 1 is a perspective view of a radiation emitting semiconductor device 10 according to embodiments . The radiation emitting semiconductor device may comprise a first semiconductor layer 110 of a first conductivity type , e . g . n- type , arranged over an active zone 115 . The radiation emitting semiconductor device 10 may further comprise a second semiconductor layer 120 of a second conductivity type , e . g . p- type . The radiation emitting semiconductor device 10 may further comprise a first contact element 130 which is arranged over a first main surface 111 of the first semiconductor layer 110. Electromagnetic radiation generated in the active zone

[0040] 115 is emitted via the first main surface 111.

[0041] As is illustrated in Fig. 1, the first contact element 130 extends along a first direction, e.g. the x-direction. As is illustrated in Fig. 1, the first contact elements 130 extend in the form of fingers. According to further embodiments, the first contact elements 130 may also have a different shape, e.g. the shape of bond pads. Several contact elements 130 may be connected to a common first contact pad 135. As is to be clearly understood, the specific shape and arrangement of the first contact element 130 may be arbitrary. For example, a material of the first contact element 130 may comprise a metal alloy, e.g. an AuGe alloy. For example, a reflectivity of the first contact element may be less than 50%, e.g. less than 30 % and more than 5 %. For example, light extraction efficiency may be affected when light obliquely emitted by the active zone 115 impinges on the lossy first contact element 130 which is in contact with the first semiconductor layer 110. As will be explained in the following with reference to Figs. 2 to 5, a trench may be arranged adjacent to the first contact element .

[0042] The semiconductor device 10 may further comprise a second contact element, e.g. a metal layer 140 which is arranged adjacent to a surface of the second semiconductor layer 120. As is to be clearly understood, the radiation emitting semiconductor device 10 may comprise further layers and, e.g. a semiconductor substrate, e.g. a growth substrate. The second contact element 140 is provided so as to be electrically connected to the second semiconductor layer 120.

[0043] For example, the first and the second semiconductor layers may be based on the InGaAlP, InGaAs, AlGaAs, InAlGaAsP material system, e . g . the semiconductor layers may have a composition of InxGayAli-x-yP, InxGai-xAs , AlxGai-xAs or InxAlyGai-x-yAszPi-z. Any of x, y, z may be in a range of 0 inclusive to 1 inclusive .

[0044] Fig . 2A is a perspective view of a portion of the radiation emitting semiconductor device . As is shown, the first contact element 130 may extend in the first direction, e . g . the x- direction . In the shown cross-sectional view, an extension length of the first contact element 130 in the first direction may be larger than the extension length of the first contact element 130 in a second hori zontal direction perpendicular to the first direction . A trench 132 is arranged adj acent to the first contact element 130 . The trench 132 extends in the first direction . In the shown cross-sectional view, an extension length of the trench 132 in the first direction may be larger than the extension length of the trench 132 in a second hori zontal direction perpendicular to the first direction . The trench 132 is formed in the first main surface 111 of the semiconductor layer 110 . As will be shown in more detail in Fig . 2B, a bottom side 133 o f the f irst contact element 130 is directly adj acent to a bottom side 131 of the trench 132 .

[0045] A portion of the first semiconductor layer 110 may be arranged below the first contact element 130 and below the trench 132 . For example , a portion of the first semiconductor layer 110 below the trench 132 may implement a current spreading layer 113 . For example , the current spreading layer 113 may have a larger doping concentration than a remaining portion of the first semiconductor layer 110 . As is further indicated in Fig . 2A, the first main surface 111 of the first semiconductor layer 110 may be textured . This will be shown in more detail in Fig . 2B . Fig. 2B shows a cross-sectional view of a portion of the radiation emitting semiconductor device 10 illustrated in Fig. 2A. The cross-sectional view of Fig. 2B is taken between I and II, as is also indicated in Fig. 1. As is shown, the radiation emitting semiconductor device 10 comprises a first semiconductor layer 110, an active zone 115 and a second semiconductor layer 120. The first semiconductor layer 110, the active zone 115 and the second semiconductor layer 120 form a semiconductor layer stack which may be epitaxially grown over a suitable growth substrate (not shown in Fig. 2B) . For example, a lower portion of the first semiconductor layer 110 may form a current spreading layer 113.

[0046] Moreover, the first main surface 111 of the first semiconductor layer 110 may be textured. Texture elements 134 of the texture may extend from a base portion 136 to a height a. The height may define a distance from a first main surface 111 of the first semiconductor layer 110 having a maximum height to the base portion 136. In more detail, the height a is measured with respect to a topmost portion of the first semiconductor layer 110 and the base portion 136. For example, the height a may be larger than 500 nm, e.g. larger than 700 nm, for example, approximately 750 nm.

[0047] A depth f of the trench 132 is larger than the height a of the texture. The depth f is measured with respect to the first main surface 111 of the first semiconductor layer 110 having the maximum height. In more detail, the depth f is also measured with respect to a topmost portion of the surface 111 of the first semiconductor layer 110. A sidewall of the trench 132 may extend at an angle of 90° or at a different angle.

[0048] As is further shown in Fig. 2B, the bottom side 133 of the first contact element 130 is directly adjacent to the bottom side 131 of the trench 132 . For example , an upper surface 129 of the first contact element 130 may be arranged below the first main surface 111 of the first semiconductor layer 110 . According to further embodiments , the upper surface 129 of the first contact element may be arranged at a lower height than the base portion 136 of the texture elements 134 .

[0049] Fig . 2B also shows radiation 15 which is emitted by the active zone 115 . As is shown, due to the presence of the trench 132 , the radiation 15 is reflected at a trench sidewall towards the first main surface 111 . In particular, oblique radiation is reflected at the trench sidewall . Accordingly, due to the presence of the trench 132 , emitted radiation may be prevented from being absorbed by the first contact element 130 . Instead of being absorbed, it is reflected at a side wall of the trench 132 and emitted via the first main surface 111 of the radiation emitting semiconductor device 10 . Accordingly, light extraction ef ficiency may be increased . For example , when a semiconductor material such as InGaAlP, AlGaAs , InGaAlAsP or InGaAs is used, a large refractive index contrast between the semiconductor material and ambient media may occur resulting in a high reflectivity .

[0050] As is indicated in Fig . 2A, it is not essential that the trench 132 continuously runs along the first contact element 130 . For example , the trench 132 may be interrupted and portions of the first semiconductor layer 110 may be arranged directly adj acent to portions of a side wall of the first contact element 130 . For example , a distance 1 between adj acent texture elements 134 may be smaller than a length t of the trench 132 measured in the first direction .

[0051] Fig . 2C shows a cross-sectional view of the radiation emitting semiconductor device 10 according to further embodiments . In addition to elements illustrated in Fig . 2B, an electrical contact layer 116 may be arranged directly adj acent to a bottom side 131 of the trench 132 and to a bottom side 133 of the first contact element 130 . For example , the electrical contact layer 116 may be made of a semiconductor material of the first conductivity type and may have a doping concentration that is higher than a doping concentration of the first semiconductor layer 110 , e . g . in a portion in which the texture elements 134 are formed or in a portion adj acent to the active zone 115 . According to further examples , the electrical contact layer 116 may have a composition that is di f ferent from a composition of the first semiconductor layer 110 e . g . in a region in which the texture elements 134 are formed . For example , the electrical contact layer 116 may be heavily doped with dopants of the first conductivity type and may establish an ohmic contact to the first contact element 130 .

[0052] According to further embodiments , the radiation emitting semiconductor device 10 may further comprise a current spreading layer 114 that may be arranged between the electrical contact layer 116 and the first semiconductor layer 110 . For example , the current spreading layer 114 may be made of a semiconductor material of the first conductivity type and may have a doping concentration that is di f ferent from a doping concentration of the first semiconductor layer 110 , e . g . in a portion in which the texture elements 134 are formed or in a region directly adj acent to the active zone 115 . According to further examples , the current spreading layer may have a composition that is di f ferent from a composition of the first semiconductor layer 110 in which the texture elements 134 are formed . A further portion of the first semiconductor layer 110 may be arranged between the current spreading layer 114 and the active zone 115 .

[0053] As is clearly to be understood, the semiconductor layer stack which forms part of the radiation emitting semiconductor device 10 according to all embodiments may comprise further layer (portions ) having di f ferent doping levels . For example , a doping concentration may vary in a vertical direction .

[0054] For example , in a region adj acent to the first main surface 111 of the first semiconductor layer 110 , in a portion comprising texture elements 134 , the semiconductor material may be undoped or doped at a low level in order to reduce absorption losses .

[0055] Fig . 3A shows a perspective view of the radiation emitting semiconductor device 10 according to further embodiments . Di f fering from embodiments which are illustrated in Fig . 2A, a portion of the first semiconductor layer 110 is arranged below the first contact element 130 . Further, optionally, a portion of the first semiconductor layer may laterally be adj acent to the first contact element 130 . As is shown, the bottom side 133 of the first contact element 130 is not directly adj acent to a bottom side 131 of the trench 132 . In more detail , the first contact element 130 is arranged over a pedestal 124 which is disposed over the bottom 131 of the trench 132 .

[0056] Fig . 3B shows an example of a cross-sectional view of the radiation emitting semiconductor device 10 . As is shown, a bottom side 133 of the first contact element 130 may be arranged at a distance d from a bottom portion 131 of the trench 132 . For example , d may be in a range o f 0 . 4 to 1 . 8 pm . It has been shown, that with increasing depth d the light extraction may be increased . As is shown, e . g . in Fig . 3B, due to the presence of the pedestal 124 below the first contact element 130 , a larger proportion of emitted electromagnetic radiation 15 may be reflected and may be emitted by the radiation emitting semiconductor device instead of being absorbed by the first contact element 130 . Accordingly, the light extraction ef ficiency may be further increased .

[0057] As is further illustrated in Fig . 3B, an upper surface 129 of the first contact element 130 may be arranged at a higher vertical position than the first main surface 111 of the first semiconductor layer 110 .

[0058] For example , a width w of the trench 132 may be larger than 200 nm . For example , the width w may correspond to a distance between the first contact element 130 and adj acent texture elements 134 .

[0059] Fig . 3C shows a further example of a cross-sectional view of the radiation emitting semiconductor device 10 . As is illustrated, a width of the first contact element 130 may be smaller than a width of the pedestal 124 . For example , the width may be measured along the y-direction . For example , "b" may refer to a distance from a side face of the first contact element 130 to an adj acent side face of the pedestal 124 .

[0060] For example , the distance b may ef fectively be one to several microns , e . g . taking into account the alignment accuracy when patterning . By setting the distance b to a larger value , an interaction of light which passes through the trench in a deflected manner with the first contact element 130 may be reduced . According to further embodiments , the radiation emitting device 10 as described in Figs . 3A to 3C may further comprise an electrical contact layer 116 and / or a current spreading layer as has been explained above .

[0061] Fig . 4A shows a perspective view of a portion of the radiation emitting semiconductor device 10 according to further embodiments . Elements of the radiation emitting semiconductor device 10 of Fig . 4A are identical with those illustrated in Figs . 2A and 3A, respectively . Di f fering from embodiments illustrated in Fig . 3A, a depth f of the trench 132 measured form the first main surface 111 may be smaller . Further, a height d of the pedestal 124 may be larger than e . g . illustrated in Figs . 2B and 3B, respectively . In more detail , as is illustrated in Figs . 4A and 4B, the first contact element 130 may be arranged over a pedestal 124 disposed adj acent to a bottom side 131 of the trench 132 . An upper surface 125 of the pedestal 124 may be arranged at a height approximately corresponding to a height of an upper surface of the texture elements 134 . In particular, a distance d between the upper surface 125 of the pedestals 124 and the bottom side 131 of the trench 132 may be larger than the di stance from the base portion 136 of the texture elements 134 to the bottom side 131 of the trench 132 . Moreover, the first contact element 130 protrudes from the texture elements 134 . In particular, a larger proportion of the first contact element 130 is arranged over the first main surface 111 of the first semiconductor layer .

[0062] As is speci fically illustrated in Fig . 4B, due to this speci fic arrangement emitted radiation 15 is reflected more ef ficiently . As a consequence , the light extraction ef ficiency may be further increased . According to embodiments , a portion of the pedestal 124 may have an arbitrarily di f ferent doping concentration as compared to other portions of the pedestal 124 , e . g . an undoped portion of the pedestal 124 .

[0063] Fig . 4C shows a cross-sectional view of the radiation emitting semiconductor device 10 according to further embodiments . In addition to elements illustrated in Fig . 4B, an electrical contact layer 116 may be arranged directly adj acent to a bottom side 133 of the first contact element 130 . A top surface of the electrical contact layer 116 may form an upper surface 125 of the pedestal 124 . For example , the electrical contact layer 116 may be made of a semiconductor material of the first conductivity type and may have a doping concentration that is higher than a doping concentration of the first semiconductor layer 110 , e . g . in a region in which the texture elements 134 are formed or in a region adj acent to the active zone 115 . Moreover, the electrical contact layer 116 may have a composition that is di f ferent from a composition of the first semiconductor layer 110 in which the texture elements 134 are formed . A further portion of the first semiconductor layer 110 may be arranged between the electrical contact layer 116 and the active zone 115 .

[0064] For example , when the radiation emitting semiconductor device 10 comprises an electrical contact layer 116 adj acent to the first contact element 130 , a hori zontal layer portion of the texture elements 134 may be doped with dopants of the first conductivity type .

[0065] The electrical contact layer 116 may also be applied to embodiments that are described with reference to Figs . 3A to 3C and 4D . Fig. 4D shows a further example of a cross-sectional view of the radiation emitting semiconductor device 10. As is illustrated, in a similar manner as has been discussed with reference to Fig 3C, a width of the first contact element 130 may be smaller than a width of the pedestal 124. For example, the width may be measured along the y-direction. For example, "b" may refer to a distance from a side face of the first contact element 130 to an adjacent side face of the pedestal 124.

[0066] For example, the distance b may effectively be one to several microns, e.g. taking into account the alignment accuracy when patterning. By setting the distance b to a larger value, an interaction of light which passes through the trench in a deflected manner with the first contact element 130 may be reduced .

[0067] Figs. 5A to 5D illustrate cross-sectional views of a workpiece 16 when performing a method according to embodiments. As is shown in Fig. 5A, a starting point may be a semiconductor layer stack 102 which may be e.g. arranged over a growth substrate (not shown in Fig. 5A) . The semiconductor layer stack 102 may comprise a first semiconductor layer 110 of a first conductivity type, e.g. n-type, an active zone 115 and a second semiconductor layer 120 of a second conductivity type, e.g. p-type. A photoresist layer 105 is formed over the first semiconductor layer 110.

[0068] As is shown in Fig. 5B, the photoresist layer 105 may be patterned to form a patterned photoresist layer 107. For example, the patterned photoresist layer 107 may comprise a plurality of pillars of a photoresist material which are arranged over the first main surface 111 of the first semiconductor layer. The photomask may be designed in such a manner that the patterned photoresist layer 107 further comprises a portion for defining the trench 132 , e . g . the center portion illustrated in Fig . 5B .

[0069] As is shown in Fig . 5C, thereafter, an etching step for etching the first semiconductor layer 110 is performed . As a consequence , holes are etched between adj acent pillars of the patterned photoresist layer 107 . Moreover, the central portion from which the photoresist material has been completely removed, is etched to form the trench 132 . For example , an etching depth of this etching process may be determined in dependence from a vertical position of the first contact element 130 .

[0070] Thereafter, the photoresist material 107 may be removed and the first contact element 130 may be formed, as is also shown in Fig . 5D . The method may be further modi fied for forming the pedestal 124 that has been discussed with reference to Figs . 3 and 4 .

[0071] Optionally, further doping processes may be formed in order to form the electrical contact layer 116 or the current spreading layer 114 in the manner as has been described with reference to Figs . 2C and 4C .

[0072] Fig . 6 summari zes a method according to embodiments . A method of manufacturing a radiation emitting semiconductor device comprises forming ( S 100 ) a photoresist layer over a semiconductor layer stack and patterning ( S l i d ) the photoresist layer in accordance with a surface texture to be formed in a first main surface of a first semiconductor layer of the semiconductor layer stack comprising removing ( S 120 ) a portion of the patterned photoresist layer in a first region of a first contact element . The method further comprises etching ( S 130 ) the first semiconductor layer in exposed portions , and forming ( S 140 ) a first contact element in the first region .

[0073] As has been discussed, due to the presence of the trench 132 adj acent to the contact element 130 , light losses due to front contact shadowing ef fects may be reduced . As a consequence , a higher outcoupling ef ficiency may be achieved . As has been shown, this new design may be implemented in a straightforward manner by etching around the first contact element 130 .

[0074] The radiation emitting semiconductor device 10 may be applied in LED (" light emitting diode" ) applications with front contacts requiring a high brightness . Examples comprise automotive or horticulture applications or general illumination devices .

[0075] While embodiments of the invention have been described above , it is obvious that further embodiments may be implemented . For example , further embodiments may comprise any subcombination of features recited in the claims or any subcombination of elements described in the examples given above . Accordingly, this spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein .

[0076] LIST OF REFERENCES radiation emitting semiconductor device emitted radiation workpiece semiconductor layer stack photoresist layer patterned photoresist layer first semiconductor layer first main surface first current spreading layer current spreading layer active zone electrical contact layer second semiconductor layer pedestal upper surface of pedestal upper surface of first contact element first contact element bottom side of trench trench bottom side of contact element texture element first contact pad base portion of texture elements second contact element

Claims

CLAIMS1. A radiation emitting semiconductor device (10) comprising : a first semiconductor layer (110) of a first conductivity type arranged over an active zone (115) , and a first contact element (130) arranged over a first main surface (111) of the first semiconductor layer (110) , electromagnetic radiation (15) generated in the active zone (15) being emitted via the first main surface (111) , the first contact element (130) extending along a first direction, a trench (132) adjacent to the first contact element (130) and extending in the first direction, the trench (132) being formed in the first main surface (111) of the first semiconductor layer (110) and extending to a bottom side (131) at a deeper depth at a position laterally adjacent to the first contact element than at a position below the first contact element, so that a pedestal (124) of the first semiconductor layer is arranged between the bottom side (131) of the trench (132) and a bottom side (133) of the first contact element (130) , wherein the first main surface (111) of the first semiconductor layer (110) is textured.

2. The radiation emitting semiconductor device (10) according to claim 1, wherein texture elements (134) of the textured first main surface (111) extend to a height a from a base portion (136) of the texture element (134) to a first main surface (111) of the first semiconductor layer (110) having a maximum height, wherein a depth f of the trench (132) is larger than the height a of the texture element (134) , the depth f beingmeasured with respect to the first main surface (111) of the first semiconductor layer (110) having the maximum height.

3. The radiation emitting semiconductor device (10) according to claim 2, wherein a distance 1 between adjacent texture elements (134) is smaller than a length t of the trench (132) measured in the first direction.

4. The radiation emitting semiconductor device (10) according to any of the preceding claims, wherein the trench (132) extends along the first contact element (130) .

5. The radiation emitting semiconductor device (10) according to any of the preceding claims, wherein a width of the first contact element (130) is smaller than the width of the pedestal (124) , wherein the width is measured in a second horizontal direction perpendicular to the first direction.

6. The radiation emitting semiconductor device (10) according to any of the preceding claims, wherein the bottom side (133) of the first contact element (130) is arranged above a base portion (136) of the texture elements (134) .

7. The radiation emitting semiconductor device (10) according to any of the preceding claims, wherein an upper surface (129) of the first contact element (130) is arranged above the first main surface (111) of the first semiconductor layer (110) .

8. The radiation emitting semiconductor device (10) according to any of the preceding claims, further comprising an electrical contact layer (116) of the first conductivity type directly adjacent to a bottom side (133) of the first contact element (130) , the electrical contact layer (116)having a doping concentration different from a doping concentration of the first semiconductor layer (110) or having a composition different from a composition of the first semiconductor layer (110) .

9. The radiation emitting semiconductor device (10) according to any of the preceding claims, wherein the first semiconductor layer (110) comprises InxGayAli-x-yP, InxGai-xAs, AlxGai-xAs, or InxAlyGai-x-yAszPi-z, wherein 0 <x,y,z<l.

10. A method of manufacturing a radiation emitting semiconductor device (10) comprising: forming (S100) a photoresist layer (105) over a semiconductor layer stack (102) ; patterning (S110) the photoresist layer (105) in accordance with a surface texture to be formed in a first main surface (111) of a first semiconductor layer (100) of the semiconductor layer stack (102) comprising removing (S120) a portion of the photoresist layer (107) in a first region of a first contact element (130) ; etching (S130) the first semiconductor layer (110) in exposed portions to form a trench (132) extending in a first direction, and extending to a bottom side (131) so that a pedestal (124) of the first semiconductor layer is arranged between the bottom side (131) of the trench (132) and a sidewall of the trench (132) ; and forming (S140) a first contact element (132) in the first region over the pedestal (124) in the trench (132) .

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