Optoelectronic component with a wireless contacting

Abstract

An optoelectronic component contains a semiconductor chip (1) and a carrier body (10), which are provided with a transparent, electrically insulating encapsulation layer (3), the encapsulation layer (3) having two cutouts (11, 12) for uncovering a contact area (6) and a connection region (8) of the carrier body, and an electrically conductive layer (14) being led from the contact area (6) over a partial region of the encapsulation layer (3) to the electrical connection region (8) of the carrier body (10) in order to electrically connect the contact area (6) and the electrical connection region (8) to one another. The radiation emitted in a main radiation direction (13) by the semiconductor chip (1) is coupled out through the encapsulation layer (3), which advantageously contains luminescence conversion substances for the wavelength conversion of the emitted radiation.

Claims

1. An optoelectronic component which emits radiation in a main radiation direction, comprising: a semiconductor chip having a first main area, a first contact area, and a second main area, opposite the first main area, with a second contact area; a carrier body having first and second electrical connection regions insulated from one another, the semiconductor chip being fixed by the first main area on the carrier body and the first contact area being electrically conductively connected to the first connection region; a transparent, electrically insulating encapsulation layer formed on the semiconductor chip and the carrier body, wherein the radiation emitted in the main radiation direction is coupled out through the encapsulation layer, and wherein the encapsulation layer is a glass layer; and a contact connection formed by an electrically conductive layer extending from the second contact area over a region of the encapsulation layer to the second electrical connection region of the carrier body, and electrically conductively connecting the second contact area to the second connection region; wherein an insulating cover layer is applied to the electrically conductive layer; and wherein the cover layer is a glass layer.

2. The optoelectronic component as claimed in claim 1, wherein the encapsulation layer contains a luminescence conversion material.

3. The optoelectronic component as claimed in claim 1, wherein the first contact area is arranged at the first main area of the semiconductor chip, the semiconductor chip being mounted by the first contact area on the first connection region by means of an electrically conductive connection.

4. The optoelectronic component as claimed in claim 1, wherein the first contact area is arranged at the second main area of the semiconductor chip, and a further electrically conductive layer is led from the first contact area over a partial region of the encapsulation layer to the first electrical connection region of the carrier body, and electrically conductively connects the first contact area to the first connection region.

5. The optoelectronic component as claimed in claim 1, wherein the electrically conductive layer is a layer that is transparent to the emitted radiation.

6. The optoelectronic component as claimed in claim 5, wherein the electrically conductive layer contains a transparent conductive oxide, preferably indium tin oxide.

7. The optoelectronic component as claimed in claim 1, wherein the electrically conductive layer is a patterned metal layer.

8. The optoelectronic component as claimed in claim 1, wherein an insulating cover layer is applied to the electrically conductive layer.

9. The optoelectronic component as claimed in claim 8, wherein the cover layer is a glass layer.

10. An illumination device containing an optoelectronic component as claimed in claim 1.

11. The illumination device as claimed in claim 10, wherein the illumination device is a headlight.

12. The illumination device as claimed in claim 11, wherein the headlight is a front headlight of a motor vehicle.

13. The illumination device as claimed in claim 10, wherein a plurality of semiconductor chips are included and a portion of adjacent semiconductor chips or all adjacent semiconductor chips are at a distance from one another of less than or equal to 300 m and greater than or equal to 0 m.

14. The illumination device as claimed in claim 13, wherein a portion of adjacent semiconductor chips or all adjacent semiconductor chips are at a distance of less than or equal to 100 m and greater than or equal to 0 m.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in more detail below on the basis of exemplary embodiments in conjunction with FIGS. 1 to 8.

(2) FIG. 1 shows a schematic illustration of a cross section through a first exemplary embodiment of an optoelectronic component according to the invention,

(3) FIGS. 2A to 2F show a schematic illustration of a first exemplary embodiment of a method according to the invention depicted as intermediate steps,

(4) FIGS. 3A to 3C show a schematic illustration of a variant of the application of the encapsulation layer and/or the cover layer in a second exemplary embodiment of a method according to the invention depicted as intermediate steps,

(5) FIG. 4 shows a schematic perspective illustration of a first exemplary embodiment of the illumination device,

(6) FIG. 5 shows a schematic perspective illustration of a second exemplary embodiment of the illumination device,

(7) FIG. 6 shows a schematic perspective illustration of a third exemplary embodiment of the illumination device,

(8) FIG. 7 shows a schematic sectional view of part of a fourth exemplary embodiment of the illumination device, and

(9) FIG. 8 shows a schematic sectional view of part of a fifth exemplary embodiment of the illumination device,

(10) FIG. 9 shows a schematic illustration of a cross section through another exemplary embodiment of an optoelectronic component.

DETAILED DESCRIPTION OF THE DRAWINGS

(11) Identical or identically acting elements are provided with the same reference symbols in the figures.

(12) The first exemplary embodiment of an optoelectronic component according to the invention as illustrated in FIG. 1 contains a carrier body 10, to which are applied two contact metallizations, which form a first connection region 7 and a second connection region 8. A semiconductor chip 1 is mounted by a first main area 2, which simultaneously constitutes the first contact area 4 in this exemplary embodiment, onto the first connection region 7. The semiconductor chip 1 is mounted onto the first connection region 7, for example by soldering or adhesive bonding. The semiconductor chip 1 has a second contact area 6 at a second main area 5 of the semiconductor chip 1, said second main area being opposite the first main area 2. As an alternative, however, it is also possible for both the first and the second contact areas 4 and 5 to be situated on the second main area of the semiconductor chip 1 and for both contact areas, with electrically conductive layers insulated from one another, to be connected to a respective one of the two connection regions of the carrier body 10, as shown in FIG. 9.

(13) The semiconductor chip 1 and the carrier body 10 are provided with an encapsulation layer 3. The encapsulation layer 3 is preferably a plastic layer. In particular, a silicone layer may be involved since a silicone layer is distinguished by a particularly good radiation resistance. The encapsulation layer 3 is particularly preferably a glass layer.

(14) The second contact area 6 and the second connection region 8 are connected to one another by an electrically conductive layer 14 led over a partial region of the encapsulation layer 3. The electrically conductive layer 14 contains for example a metal or an electrically conductive transparent oxide (TCO), for example indium tin oxide (ITO), ZnO:Al or SnO:Sb.

(15) In order to obtain a potential-free surface, an insulating cover layer 15, for example a resist layer, is advantageously applied to the electrically conductive layer 14. In the case of a transparent insulating cover layer 15, the latter advantageously need not be patterned and can therefore be applied to the optoelectronic component over the whole area. Partial regions 16, 17 of the connection areas 7, 8 are advantageously kept uncovered by the encapsulation layer 3 and the cover layer 15, so that electrical connections for the power supply of the optoelectronic component can be fitted in these uncovered partial regions 16, 17.

(16) The encapsulation layer 3 protects the semiconductor chip 1 against ambient influences, in particular against dirt or moisture. The encapsulation layer 3 furthermore functions as an insulating carrier of the electrically conductive layer 14, which carrier prevents a short circuit of the lateral flank of the semiconductor chip 1 and/or of the two connection areas 7 or 8 of the carrier body.

(17) In addition, the radiation emitted in a main radiation direction 13 by the semiconductor chip 1 is also coupled out from the optoelectronic component through the encapsulation layer 3. This has the advantage that a luminescence conversion material can be added to the encapsulation layer 3, said material shifting the wavelength of at least one portion of the emitted radiation toward longer wavelengths. In particular, white light can be generated in this way by virtue of the radiation generated by a semiconductor chip 1 that emits in the blue or ultraviolet spectral range being partly converted into the complementary yellow spectral range. A semiconductor chip 1 comprising a radiation-generating active zone containing a nitride compound semiconductor material such as, for example, GaN, AlGaN, InGaN or InGaAlN is preferably used for this purpose.

(18) An exemplary embodiment of a method according to the invention is explained in more detail below on the basis of schematically illustrated intermediate steps with reference to FIGS. 2A to 2F.

(19) FIG. 2A shows a carrier body 10, on which two connection regions 7, 8 electrically insulated from one another are formed, for example by application and patterning of a metallization layer.

(20) In the case of the intermediate step illustrated in FIG. 2B, a semiconductor chip 1 having a first main area 2 and second main area 5 is mounted by a first contact area 4, which is identical to the second main area 2 of the semiconductor chip 1 in this exemplary embodiment onto the first connection region 7 of the carrier body 10. The semiconductor chip 1 is mounted onto the carrier body 10 for example by means of a soldering connection or an electrically conductive adhesive. The semiconductor chip 1 has a second contact area 6 at the second main area 5, said second contact area being formed for example from a contact layer or contact layer sequence which is applied to the second main area 5 and is patterned by means of photolithography, for example.

(21) FIG. 2C illustrates an intermediate step in which an encapsulation layer 3 is applied to the semiconductor chip 1 and the carrier body 10 provided with the connection regions 7, 8. The encapsulation layer 3 is preferably applied by spraying on or spin-coating of a polymer solution. Furthermore, a printing method, in particular screen printing, is also advantageous for the application of the encapsulation layer 3.

(22) In the case of the method step illustrated in FIG. 2D, a first cutout 11, through which a partial region of the second contact area 6 is uncovered, and a second cutout 12 through which a partial region of the second connection region 8 of the carrier body 10 is uncovered, are produced in the encapsulation layer 3. The cutouts 11, 12 are preferably produced by laser machining. A partial region 16 of the first connection region 7 and a partial region 17 of the second connection region 8 are advantageously uncovered, too, in order to enable the fitting of electrical connections at the carrier body 10 of the optoelectronic component.

(23) In the case of the intermediate step illustrated in FIG. 2E, the second contact area 6 uncovered beforehand through the cutout 11 is electrically conductively connected, by means of an electrically conductive layer 14, to that region of the second connection area 8 that was uncovered beforehand through the cutout 12.

(24) The electrically conductive layer 14 is a metal layer, for example. This layer is applied for example in such a way that firstly a comparatively thin metal layer, having a thickness of approximately 100 nm, for example, is applied to the encapsulation layer 3 over the whole area. This may be done by vapor deposition or sputtering, for example. A photoresist layer (not illustrated) is subsequently applied to the metal layer, in which a cutout is produced by means of phototechnology in the region in which the electrically conductive layer 14 is intended to connect the second contact area 6 to the second connection region 8.

(25) In the region of the cutout in the photoresist layer, the previously applied metal layer is reinforced by an electrodeposition. This is advantageously effected in such a way that the metal layer in the galvanically reinforced region is significantly thicker than the metal layer previously applied over the whole area. By way of example, the thickness of the metal layer in the galvanically reinforced region may be several (m. The photoresist layer is subsequently removed and an etching process is carried out, by means of which the metal layer is completely removed in the region that has not been galvanically reinforced. In the galvenically reinforced region, by contrast, on account of its greater thickness the metal layer is removed only in part, with the result that it remains as electrically conductive layer 14 in this region.

(26) As an alternative, it is also possible for the electrically conductive layer 14 to be applied to the encapsulation layer 3 directly in patterned form. This may be effected for example by means of a printing method, in particular by means of a screen printing method.

(27) A patterning or a patterned application of the electrically conductive layer 14 is advantageously not required if an electrically conductive layer 14 that is transparent to the emitted radiation is applied. In particular a transparent conductive oxide (TCO), preferably indium tin oxide (ITO) or alternatively an electrically conductive plastic layer is suitable as the electrically conductive transparent layer. The electrically conductive transparent layer is preferably applied by vapor deposition, printing on, spraying on or spin-coating.

(28) In the case of the method step illustrated in FIG. 2F, an electrically insulating cover layer 15 is applied. The insulating cover layer 15 is preferably a plastic layer, for example a resist layer. The insulating cover layer 15 covers in particular the electrically conductive layer 14 in order to produce a potential-free surface.

(29) An alternative variant of the application of the encapsulation layer 3, that is to say of the intermediate step illustrated previously in FIG. 2C, is explained below with reference to FIGS. 3A, 3B and 3C.

(30) In this case, firstly a precursor layer 9 containing both organic and inorganic constituents is applied to the semiconductor chip 1 and the carrier body 10.

(31) The precursor layer is applied for example by means of a sol-gel method, by vapor deposition, sputtering, spraying on or by spin-coating of a suspension.

(32) By means of a thermal treatment at a temperature T1 of preferably approximately 200 C. to 400 C. for approximately 4 h to 8 h in a neutral N2 atmosphere or under low O2 partial pressure, the organic constituents of the precursor layer 9 are removed, as indicated by the arrows 18 in FIG. 3B.

(33) The resultant layer is subsequently densified by means of a sintering process, as is illustrated schematically in FIG. 3C, in order to produce the encapsulation layer 3. The sintering is effected by means of a further thermal treatment at a temperature T2 of preferably approximately 300 C. to 500 C. for approximately 4 h to 8 h. Depending on the type of glass layer, the sintering is preferably carried out under a reducing or oxidizing atmosphere.

(34) The method steps described in FIGS. 3A, 3B and 3C can analogously also be used for producing a cover layer 15 composed of a glass. In this case, said method steps are preferably carried out a first time in order to produce an encapsulation layer 3 composed of a glass, and are repeated after the application of the electrically conductive layer 14 in order to deposit a cover layer 15 made of a glass.

(35) Through multiple repetition of the application of an electrically insulating layer and an electrically conductive layer, it is also possible to realize multilayer interconnections. This is advantageous in particular for LED modules containing a plurality of semiconductor chips.

(36) FIGS. 4 to 8 illustrate illumination devices comprising at least one optoelectronic component, which in each case have at least one optical element 19, each semiconductor chip 1 of the optoelectronic component being assigned an optical element.

(37) In the case of the optoelectronic component illustrated in FIG. 6, a plurality of optical elements 19 are arranged above the semiconductor chips, and are formed integrally with one another, by way of example. By contrast, the optoelectronic component illustrated in FIG. 4 has a single optical element. This optical element 19 is formed in CPC-like fashion.

(38) Each semiconductor chip 1 of the optoelectronic component is assigned to a single optical element 19, for example. A beam entrance of the optical elements that faces the semiconductor chips has a radiation entrance opening whose sides are e.g. (1.5 times a corresponding horizontal edge length of the semiconductor chips, preferably (1.25 times said edge length. If such a small beam entrance is arranged as close as possible to the semiconductor chip, a divergence of the radiation emitted by the semiconductor chips can be effectively reduced and a beam cone having a high luminance can be generated.

(39) Instead of each semiconductor chip being assigned a single dedicated optical element 19, the optical element 19 may also be provided for a plurality of semiconductor chips 1, as is the case for example for the optical element 19 of the component illustrated in FIG. 5. This optical element 19 is also formed in the manner of a CPC. The optical element 19 is provided for six semiconductor chips 1, by way of example.

(40) In order to achieve a highest possible efficiency, the semiconductor chips 1 should be arranged as close together as possible. At least a portion of adjacent semiconductor chips 1 are at a distance of (50 (m from one another, by way of example. Particularly preferably, said semiconductor chips are at substantially no distance from one another.

(41) As an alternative to a CPC-like concentrator, the optical element 19 has for example side walls which run in straight lines from the beam entrance to the beam exit. An example of optical elements 19 of this type is illustrated in FIG. 6. In the case of optical elements 19 of this type, the beam exit is preferably provided with a spherical or aspherical lens or is curved outward in the manner of such a lens.

(42) The advantage of an aspherical curvature, compared with a spherical curvature, is that the aspherical curvature decreases for example as the distance from the optical axis of the optical element 19 increases. This takes account of the circumstance that the beam cone whose divergence is to be reduced by means of the optical element 19 is not a point-type light radiation source, but rather a radiation source having a certain extent.

(43) Such an optical element having reflective walls running straight from the beam entrance to the beam exit has the advantage, compared with a CPC-like optical element, that it can result in a comparable reduction of the divergence of a beam cone in conjunction with a significant reduction of the structural height of the optical element 19. A further advantage of such optical elements is that their straight lateral faces can be produced more simply by means of a molding method such as injection molding or transfer molding, for example, while the formation of curved lateral faces as in the case of CPC-like concentrators is comparatively difficult.

(44) The optical element is preferably a dielectric concentrator with a basic body composed of a dielectric material. As an alternative, however, the use of a concentrator with a basic body that defines a corresponding cavity with reflective inner walls is also possible.

(45) If the optical element 19 is formed in the manner of a dielectric concentrator, additional fixing devices are generally necessary in order to position the optical element 19 on or relative to the semiconductor chips.

(46) The optical elements illustrated in FIGS. 4 and 6 have holding elements 120 which extend in the vicinity of the beam exit of the optical element and, respectively, the optical elements 19 away from the dielectric basic body and project away laterally from the latter and also run at a distance from the basic body in the direction of the beam entrance.

(47) The holding elements 120 may comprise pillar-like elements, for example, on which the optical elements can be set up and therefore positioned relative to the semiconductor chips 1.

(48) As an alternative to holding elements 120 of this type, the optical elements 19 can also be mounted and positioned by means of separate mounting devices. By way of example, they can be inserted into a separate frame.

(49) The components illustrated in FIGS. 4 and 6 are optoelectronic modules having a module carrier 20. There are formed on or in the module carrier electrical conductor tracks and a mating connector 25, via which the module can be electrically connected by means of a corresponding connector.

(50) In the case of the component illustrated in FIG. 7, the optical element 19 is applied on the insulating cover layer 15 directly in such a way that the beam entrance of the optical element 19 adjoins said layer. In this case, the cover layer 15 functions as a coupling material for the optical element. As an alternative, the coupling material may also be applied in the form of an additional layer on the semiconductor chip 1. A coupling material should be understood to mean, for example, a dielectric material which is transmissive to the radiation emitted by the semiconductor chips 1 and has a refractive index which preferably corresponds to that of a semiconductor material of the semiconductor chips 1, with the result that Fresnel losses and total reflections at interfaces between the semiconductor chip 1 and the optical element 19 are significantly reduced.

(51) Fresnel losses are losses owing to reflections at interfaces at which there is a sudden change in refractive index. A typical example is the sudden change in refractive index between air and a dielectric material. For example when electromagnetic radiation enters into or emerges from an optical element.

(52) The semiconductor chip 1 is therefore optically coupled to the dielectric basic body of the optical element 19 by means of the coupling material. The coupling material is for example a radiation-transmissive gel having a refractive index which is either adapted to the refractive index of their dielectric body of the optical element 19 or to the refractive index of a semiconductor material of the semiconductor chips 1 or lies between the refractive indices of these two materials. As an alternative to a gel, it is also possible for example to use an epoxy resin or a resist-like material.

(53) The refractive index of the coupling material preferably lies between that of the dielectric body of the optical element 19 and that of a semiconductor material of the semiconductor chips 1. What is essential is that the refractive index is significantly greater than 1. By way of example, a coupling material is used for the coupling medium whose refractive index is greater than 1.3, preferably greater than 1.4. Silicones, for example, are appropriate for this. However, other substances such as e.g. liquids are also possible as coupling medium. Water has, for example, a refractive index of greater than approximately 1.3 and is suitable, in principle, as coupling medium.

(54) In the case of the exemplary embodiment illustrated in FIG. 8, there is a gap 5, for example an air gap between the semiconductor chip 1 and the optical element 19. As an alternative, the gap 5 may also be filled with some other gas and it is likewise possible for a vacuum to prevail in the gap 5. The gap has the effect that a highly divergent portion of the radiation emitted by the semiconductor chip 1, on account of reflections at the interfaces, couples into the optical element 19 to a lesser extent than a low-divergence portion. This may be advantageous for the generation of highly collimated beam cones and also in applications in which a highly divergent portion might be disturbing. One example thereof is projection applications.

(55) In the case of the exemplary embodiment illustrated in FIG. 7, the distance between the beam entrance of the optical element and the semiconductor chip 1 is less than 100 (m, e.g. only approximately 60 (m. In the case of the exemplary embodiment illustrated in FIG. 8, the distance between the beam entrance of the optical element and the semiconductor chip is e.g. 180 (m.

(56) The invention is not restricted by the description on the basis of the exemplary embodiments. Moreover, the invention encompasses any new feature and also any combination of features, which in particular comprises any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.