WO2023227324A1 - Optoelectronic device and method for producing an optoelectronic device - Google Patents

Optoelectronic device and method for producing an optoelectronic device Download PDF

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Publication number
WO2023227324A1
WO2023227324A1 PCT/EP2023/061247 EP2023061247W WO2023227324A1 WO 2023227324 A1 WO2023227324 A1 WO 2023227324A1 EP 2023061247 W EP2023061247 W EP 2023061247W WO 2023227324 A1 WO2023227324 A1 WO 2023227324A1
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WO
WIPO (PCT)
Prior art keywords
light emitting
semiconductor chip
emitting semiconductor
reflective
optoelectronic device
Prior art date
Application number
PCT/EP2023/061247
Other languages
French (fr)
Inventor
Hui Yuen PENG
Alexander Wilm
Thomas Schlereth
Wee Kie TANG
Kean Khuan KOO
Tsu Pin CHNG
Ee Lian LEE
Original Assignee
Ams-Osram International Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ams-Osram International Gmbh filed Critical Ams-Osram International Gmbh
Publication of WO2023227324A1 publication Critical patent/WO2023227324A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/52—Encapsulations
    • H01L33/56—Materials, e.g. epoxy or silicone resin
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58—Optical field-shaping elements
    • H01L33/60—Reflective elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H01L2933/005—Processes relating to semiconductor body packages relating to encapsulations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H01L2933/0058—Processes relating to semiconductor body packages relating to optical field-shaping elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H01L2933/0066—Processes relating to semiconductor body packages relating to arrangements for conducting electric current to or from the semiconductor body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58—Optical field-shaping elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/62—Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Definitions

  • An optoelectronic device and a method for producing an optoelectronic device are speci fied herein .
  • At least one obj ect of certain embodiments is to speci fy an optoelectronic device with an increased ef ficiency .
  • At least one obj ect of certain embodiments is to speci fy a method for producing an optoelectronic device with an increased ef ficiency .
  • the optoelectronic device comprises a carrier .
  • the carrier is configured for a mechanical stabili zation of the optoelectronic device .
  • the carrier may be configured to dissipate heat generated during operation of the optoelectronic device .
  • the carrier comprises a ceramic material or a metal , or consists of a ceramic material or a metal .
  • the carrier comprises a main surface extending in lateral directions .
  • a direction perpendicular to the main surface of the carrier is denoted as a vertical direction in the following .
  • the vertical direction is perpendicular to the lateral directions .
  • the optoelectronic device comprises a light emitting semiconductor chip arranged on the carrier .
  • the light emitting semiconductor chip is arranged on the main surface of the carrier .
  • a light emission surface of the light emitting semiconductor chip faces away from the carrier .
  • the light emission surface extends in lateral directions .
  • the light emission surface is parallel to the main surface of the carrier .
  • a direction normal to the light emission surface is thus parallel to the vertical direction .
  • the light emitting semiconductor chip is configured to emit electromagnetic radiation in a spectral range between infrared light and ultraviolet light , for example .
  • Electromagnetic radiation generated during operation is partly emitted in the vertical direction via the light emission surface of the light emitting semiconductor chip .
  • electromagnetic radiation is emitted in a range of emission angles .
  • the light emitting semiconductor chip emits electromagnetic radiation in a range of emission angles following a Lambertian emission pattern .
  • an emission angle denotes an angle between the vertical direction and an emission direction of electromagnetic radiation emitted by the light emitting semiconductor chip .
  • electromagnetic radiation is partly emitted at an emission angle of 0 ° .
  • At least a part of the electromagnetic radiation generated during operation may be emitted at emission angles between 0 ° and 90 ° , inclusive .
  • An emission angle of 90 ° corresponds to a lateral emission direction .
  • at least a part of the electromagnetic radiation generated during operation may be emitted at emission angles larger than 90 ° .
  • at least a part of the electromagnetic radiation generated during operation may be emitted via side faces of the light emitting semiconductor chip .
  • the light emitting semiconductor chip comprises a light emitting diode or is formed as a light emitting diode .
  • the light emitting diode comprises a semiconductor layer stack .
  • the semiconductor layer stack further comprises an active region configured for generating electromagnetic radiation during operation of the light emitting semiconductor chip .
  • the active region comprises a pn-j unction .
  • the semiconductor stack preferably comprises a I I I /V compound semiconductor material .
  • a I I I /V compound semiconductor material comprises at least one element from the third main group, such as B, Al , Ga, In, and one element from the fi fth main group, for example N, P, As .
  • the term " I I I /V compound semiconductor material" includes the group of binary, ternary or quaternary compounds containing at least one element from the third main group and at least one element from the fi fth main group .
  • the I I I /V semiconductor material may comprise one or more dopants .
  • the light emitting semiconductor chip may further comprise a light conversion element .
  • the light conversion element comprises a phosphor configured for converting the electromagnetic radiation generated in the active region .
  • the phosphor may be configured to convert electromagnetic radiation in a first spectral range into electromagnetic radiation in a second spectral range .
  • the phosphor converts blue light into red and/or green and/or yellow light .
  • the optoelectronic device emits then, for example , white light mixed from the converted light and the electromagnetic radiation generated in the active region .
  • the optoelectronic device comprises a reflective encapsulation disposed on the carrier .
  • the reflective encapsulation covers at least parts of the carrier and at least parts of the light emitting semiconductor chip, such that the light emission surface of the light emitting semiconductor chip remains free of the reflective encapsulation .
  • the reflective encapsulation at least partially covers side faces of the light emitting semiconductor chip .
  • side faces extend in vertical direction and/or are arranged perpendicular or inclined to the light emission surface of the light emitting semiconductor chip .
  • the reflective encapsulation is configured to deflect electromagnetic radiation emitted by the light emitting semiconductor chip at emission angles larger than 90 ° .
  • electromagnetic radiation at emission angles larger than 90 ° is deflected to emission angles smaller than 90 ° .
  • the reflective encapsulation reflects at least 50% of the incident electromagnetic radiation, for example .
  • the reflective encapsulation reflects at least 80% of the incident electromagnetic radiation .
  • the reflective encapsulation comprises a matrix material and a filler material .
  • the matrix material may comprise a resin, such as a silicone resin or an epoxy resin, for example .
  • the filler material is a powder of small light-reflective particles embedded in the matrix material .
  • the filler material comprises a light- reflective oxide , such as titanium dioxide , for example .
  • the optoelectronic device comprises a reflective element disposed on the reflective encapsulation, wherein the reflective element completely surrounds the light emitting semiconductor chip in lateral directions .
  • the reflective element is configured to deflect electromagnetic radiation emitted by the light emitting semiconductor chip at emission angles larger than or equal to 90 ° . Electromagnetic radiation incident on the reflective element is deflected due to specular reflection or di f fuse reflection by the reflective element , for example .
  • the reflective element is configured to deflect electromagnetic radiation emitted by the light emitting semiconductor chip at emission angles larger than or equal to 70 ° .
  • the reflective element deflects electromagnetic radiation into a range of emission angles between 0 ° and 70 ° , inclusive .
  • the reflective element is formed as a dam that completely surrounds the light emitting semiconductor chip in lateral directions .
  • the reflective element is not in direct contact with the light emitting semiconductor chip .
  • a gap is arranged between the reflective element and the light emitting semiconductor chip .
  • the reflective element is in direct contact with the reflective encapsulation . It is in particular possible that there is no direct contact between the carrier and the reflective element .
  • the reflective element is , for example , connected and attached exclusively to the reflective encapsulation .
  • the reflective element deflects at least 50% of the incident electromagnetic radiation, for example .
  • the reflective element deflects at least 80% of the incident electromagnetic radiation .
  • the optoelectronic device comprises :
  • a reflective encapsulation disposed on the carrier, covering at least parts of the carrier and at least parts of the light emitting semiconductor chip, such that a light emission surface of the light emitting semiconductor chip remains free of the reflective encapsulation
  • the reflective element completely surrounds the light emitting semiconductor chip in lateral directions .
  • the optoelectronic device described herein is based on the idea that the reflective element disposed on the reflective encapsulation increases a light extraction and therefore an ef ficiency of the optoelectronic device .
  • the optoelectronic device may comprise a lens configured for directing electromagnetic radiation from the light emitting semiconductor chip to an application .
  • electromagnetic radiation emitted at large emission angles for example emission angles larger than 70 °
  • electromagnetic radiation emitted at emission angles larger than 70 ° may be directed at a fixture , such as a housing, that may have a low reflectivity .
  • electromagnetic radiation emitted at large emission angles may be trapped in the optoelectronic device , for example . Accordingly, electromagnetic radiation emitted by the light emitting semiconductor chip at large emission angles may be wasted, thereby decreasing an ef ficiency of the optoelectronic device without a reflective element .
  • the reflective element described herein may be configured to deflect electromagnetic radiation emitted from the light emitting semiconductor chip at large emission angles , for example larger than approximately 70 ° , to smaller emission angles , for example smaller than 70 ° .
  • An optoelectronic device without the reflective element may radiate approximately 6% of the electromagnetic radiation generated by the light emitting semiconductor chip at emission angles larger than 70 ° , for example .
  • This electromagnetic radiation may not be usable for applications and thus may be wasted .
  • the reflective element is configured to redirect this electromagnetic radiation into a range of emission angles smaller than 70 ° , for example , such that it is usable in applications , thereby increasing the ef ficiency of the optoelectronic device by up to 6% , for example .
  • the carrier comprises an electrical contact pad for electrically contacting the light emitting semiconductor chip, and the electrical contact pad is at least partially covered by the reflective encapsulation .
  • the electrical contact pad is configured to provide external electrical energy to the light emitting semiconductor chip .
  • the light emitting semiconductor chip is electrically connected to the electrical contact pad via a bond wire , and the reflective element at least partially covers the bond wire .
  • the reflective encapsulation is arranged such that it partially covers the contact pad and the bond wire , for example .
  • the light emitting semiconductor chip may be electrically connected to two separate contact pads via two separate bond wires , for example .
  • the bond wires are connected to electrical contacts on the light emission surface of the light emitting semiconductor chip .
  • the light emitting semiconductor chip is a flip-chip with electrical contacts on the light emission surface facing away from the carrier .
  • the light emitting semiconductor chip may be directly arranged on the electrical contact pad .
  • the light emitting semiconductor chip is a flip-chip with electrical contacts on a side facing the carrier .
  • the electrical contacts of the light emitting semiconductor chip are arranged on a surface opposite to the light emission surface .
  • the electrical contacts of the flip-chip are directly soldered onto the electrical contact pads on the carrier .
  • a thickness of the reflective encapsulation decreases with increasing distance from the light emitting semiconductor chip .
  • the thickness refers to a spatial extension in vertical direction .
  • the thickness of the reflective encapsulation decreases with increasing distance in lateral direction from the light emitting semiconductor chip .
  • the matrix material of the reflective encapsulation adheres to side faces of the light emitting semiconductor chip and therefore has a larger thickness in the vicinity of the light emitting semiconductor chip .
  • the reflective element completely proj ects above the light emitting semiconductor chip in a direction perpendicular to the light emission surface by not more than 100 pm .
  • the reflective element extends in vertical direction beyond the light emitting semiconductor chip .
  • the reflective element preferably extends in vertical direction beyond the light emitting semiconductor chip by not more than 100 pm .
  • the reflective element proj ects above the light emitting semiconductor chip such that electromagnetic radiation emitted by the light emitting semiconductor chip at emission angles larger than 70 ° is incident on the reflective element and thus deflected by the reflective element .
  • the reflective element comprises a matrix material with an oxide filler .
  • the matrix material comprises a resin, such as a silicone or an epoxy resin, for example .
  • the oxide filler preferably comprises a powder of reflective particles comprising an oxide , for example titanium dioxide .
  • the reflective particles are configured to reflect or deflect electromagnetic radiation emitted by the light emitting semiconductor chip during operation .
  • the reflective particles have a reflectivity of more than 80% for electromagnetic radiation emitted by the light emitting semiconductor chip .
  • the reflective element may be directly disposed on the reflective encapsulation .
  • the matrix material of the reflective encapsulation and the matrix material of the reflective element are from the same material family .
  • both matrix materials comprise silicone .
  • a risk of delamination is thereby reduced .
  • the reflective element comprises a frame adhesively connected to the reflective encapsulation .
  • the reflective element is a preformed frame , such as a molded frame .
  • the frame is glued onto the reflective encapsulation .
  • the frame has flat reflective surfaces configured to reflect incident electromagnetic radiation into a predetermined range of emission angles .
  • this allows to adj ust and/or tune an emission characteristic of the optoelectronic device .
  • the optoelectronic device comprises a first lens arranged above the light emission surface of the light emitting semiconductor chip .
  • the first lens is configured to increase an extraction of electromagnetic radiation emitted by the light emitting semiconductor chip .
  • the first lens is configured to redirect electromagnetic radiation emitted by the light emitting semiconductor chip at large emission angles to smaller emission angles .
  • the first lens is configured to increase an intensity of electromagnetic radiation emitted in vertical direction .
  • the first lens completely covers the carrier in a top view of the optoelectronic device .
  • the first lens is molded over the light emitting semiconductor chip and the carrier .
  • the first lens is a hal f- spherical lens configured for an improved light extraction from the optoelectronic device .
  • the optoelectronic device further comprises a second lens disposed directly on the light emission surface of the light emitting semiconductor chip, such that the second lens is arranged between the light emitting semiconductor chip and the first lens .
  • the second lens is configured to improve the light extraction from the light emitting semiconductor chip .
  • the second lens comprises an ultra-high refractive index silicone , for example .
  • the refractive index of the ultra-high refractive index silicone is at least 1 , 6 .
  • a method for producing an optoelectronic device is speci fied .
  • the method is configured to produce an optoelectronic device as speci fied herein . All features of the optoelectronic device are also speci fied for the method for producing an optoelectronic device and vice versa .
  • a light emitting semiconductor chip mounted on a carrier is provided .
  • the light emitting semiconductor chip is glued and/or soldered onto a main surface of the carrier .
  • the light emitting semiconductor chip is electrically connected to electrical contact pads on the main surface of the carrier .
  • a reflective encapsulation is disposed on the carrier, covering at least parts of the carrier and at least parts of the light emitting semiconductor chip, such that a light emission surface of the light emitting semiconductor chip remains free of the reflective encapsulation .
  • the reflective encapsulation comprises a resin that is applied to the main surface of the carrier .
  • the reflective encapsulation may be applied via dispensing or printing, for example .
  • the reflective encapsulation is applied such that side surfaces of the light emitting semiconductor chip are at least partially covered by the reflective encapsulation .
  • a reflective element is disposed on the reflective encapsulation .
  • the reflective element comprises a high viscosity silicone .
  • the high viscosity silicone is applied around the semiconductor chip, such that it forms a dam .
  • the viscosity is large enough such that the form of the dam remains relatively stable until the high viscosity silicone or the high viscosity resin is cured .
  • the reflective element proj ects above the light emitting semiconductor chip in a vertical direction .
  • the reflective encapsulation and the reflective element comprise di f ferent resins , and before curing the resin of the reflective encapsulation has lower viscosity than the resin of the reflective element .
  • the viscosity of the resin of the reflective element is large enough such that a dam can be formed and its shape remains substantially stable until the resin is cured .
  • the resin of the reflective encapsulation is at least partially cured before the resin of the reflective element is disposed directly on the reflective encapsulation .
  • the resin of the reflective encapsulation is at least partially cured such that it forms a relatively stable surface upon which the resin of the reflective element can be disposed .
  • the reflective element comprises a matrix material from the same or a similar material family as the matrix material of the reflective encapsulation .
  • both matrix materials comprise a silicone . Therefore , mechanically stable chemical bonds may form between the reflective element and the reflective encapsulation upon full curing of the matrix materials . Accordingly, a risk of delamination is advantageously decreased .
  • the reflective element comprises a molded frame and is adhesively glued onto the reflective encapsulation .
  • a first lens is molded over the carrier, the light emitting semiconductor chip, the reflective encapsulation, and the reflective element .
  • the first lens is a hal f-spherical lens .
  • the first lens comprises a silicone , for example .
  • a second lens is disposed directly on the light emission surface of the light emitting semiconductor chip before the first lens is molded over the carrier and the light emitting semiconductor chip .
  • the second lens comprises an ultra-high refractive index silicone , for example .
  • the ultra-high refractive index silicone is dispensed inside the dam formed by the reflective element such that it forms an overcast profile on the light emission surface .
  • the dam forms a stopping point for the overcast profile .
  • the stopping point allows for an easier control of the thickness and a shape of the overcast profile .
  • Figures 1 and 2 show schematic cross-sections of an optoelectronic device according to an exemplary embodiment .
  • Figure 3 to 6 show schematic cross-sections of optoelectronic devices according to further exemplary embodiments .
  • Figures 7 and 8 show schematic plan views of optoelectronic devices according to di f ferent exemplary embodiments .
  • Figure 9 shows a schematic cross-section of an optoelectronic device according to a further exemplary embodiment .
  • Figure 10 shows a flow diagram with steps of a method for producing an optoelectronic device according to an exemplary embodiment .
  • the optoelectronic device comprises a carrier 1 with a main surface 11 extending in lateral directions L .
  • a light emitting semiconductor chip 2 is arranged on the main surface 11 .
  • the carrier comprises 1 a ceramic material and the light emitting semiconductor chip 2 is a light emitting diode .
  • the light emitting semiconductor chip 2 is electrically connected to electrical contact pads 6 on the main surface 11 of the carrier 1 .
  • a bond wire 7 electrically connects the light emitting semiconductor chip 2 to an electrical contact pad 6 .
  • the light emitting semiconductor chip 2 is directly soldered onto a further electrical contact pad 6 .
  • the light emitting semiconductor chip 2 has a light emission surface 4 on a side facing away from the carrier 1 .
  • Electromagnetic radiation 10 (not shown, see Figure 2 ) emitted by the light emitting semiconductor chip 2 during operation is primarily emitted through the light emission surface 4 . A part of the electromagnetic radiation 10 may be emitted through side faces of the light emitting semiconductor chip 2 .
  • a reflective encapsulation 3 is disposed on the main surface 11 of the carrier 1 .
  • the reflective encapsulation 3 at least partially covers side faces of the light emitting semiconductor chip 2 .
  • the reflective encapsulation 3 at least partially covers the electrical contact pads 6 .
  • a thickness D of the reflective encapsulation decreases with increasing lateral distance from the light emitting semiconductor chip 2 .
  • the reflective encapsulation 3 is configured to reflect at least parts of the electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 in a direction towards the main surface 11 of the carrier 1 .
  • the reflective encapsulation 3 redirects the electromagnetic radiation 10 towards a vertical direction V . Therefore , the reflective encapsulation 3 increases a light extraction in the vertical direction V .
  • the reflective encapsulation 3 comprises a matrix material and an oxide filler .
  • the matrix material comprises a silicone
  • the oxide filler comprises a powder of titanium dioxide particles .
  • the reflective encapsulation 3 reflects at least 80% of the incident electromagnetic radiation 10 generated by the light emitting semiconductor chip 2 during operation .
  • a reflective element 5 is disposed on the reflective encapsulation 3 and completely surrounds the light emitting semiconductor chip 2 in lateral directions L .
  • the reflective element 5 proj ects above the light emission surface 4 of the light emitting semiconductor chip 2 . In other words , the reflective element 5 extends beyond the light emitting semiconductor chip 2 in vertical direction V .
  • the bond wire 7 is partially covered by the reflective element 5 .
  • the reflective element 5 is configured to deflect at least parts of the electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 in lateral direction L, for example .
  • the electromagnetic radiation 10 is deflected towards the vertical direction V .
  • the reflective element 5 deflects at least 80% of the incident electromagnetic radiation 10 generated by the light emitting semiconductor chip 2 during operation . Therefore , the reflective element 5 increases the light extraction and thus an ef ficiency of the optoelectronic device .
  • the reflective element 5 comprises a matrix material and an oxide filler .
  • the matrix material is a resin, for example a silicone .
  • the matrix material of the reflective element 5 is from the same material family as the matrix material of the reflective encapsulation 3 .
  • both matrix materials comprise a silicone . Therefore , mechanically stable bonds may form between the reflective encapsulation 3 and the reflective element 5 upon curing of the matrix materials . Accordingly, a risk of delamination is advantageously reduced .
  • the optoelectronic device further comprises a first lens 8 completely covering the main surface 11 of the carrier 1 in a top view along the vertical direction V .
  • the first lens 8 is arranged above the light emitting semiconductor chip 2 , the reflective encapsulation 3 , the reflective element 5 and the carrier 1 .
  • the first lens 8 is a hal f-spherical , molded lens configured to enhance the light extraction and thus the ef ficiency of the optoelectronic device .
  • Figure 2 shows a schematic cross-section of an optoelectronic device according to the exemplary embodiment described in connection with Figure 1 .
  • Figure 2 schematically shows electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 during operation .
  • the electromagnetic radiation 10 is emitted in a range of emission angles a between 0 ° and more than 90 ° , for example .
  • the emission angle a denotes an angle between the vertical direction and an emission direction of the electromagnetic radiation 10 .
  • the reflective element 5 proj ects above the light emitting semiconductor chip 2 such that electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 at emission angles a larger than 70 ° is incident on the reflective element 5 .
  • the reflective element 5 deflects the electromagnetic radiation 10 into a range of emission angles a smaller than or equal to 70 ° , thereby increasing the light extraction and thus the ef ficiency of the optoelectronic device .
  • Figure 3 shows a schematic cross-section of an optoelectronic device according to a further exemplary embodiment .
  • the reflective element 5 comprises a molded frame 12 that is arranged on the reflective encapsulation 3 .
  • the molded frame 12 is glued onto a top surface of the reflective encapsulation 3 .
  • the molded frame 12 completely surrounds the light emitting semiconductor chip 2 in lateral directions L and completely proj ects above the light emission surface 4 of the light emitting semiconductor chip 2 in vertical direction V .
  • reflective surfaces of the molded frame 12 are configured such that incident electromagnetic radiation 10 is deflected by the molded frame 12 into a predetermined range of emission angles a .
  • the molded frame deflects light emitted at emission angles a of at least 70 ° into a range of emission angles a between 0 ° and 20 ° , inclusive .
  • Figure 4 shows a schematic cross-section of an optoelectronic device according to a further exemplary embodiment .
  • the reflective element 5 does not cover the bond wires 7 .
  • the reflective element 5 proj ects above the light emission surface 4 of the light emitting semiconductor chip 2 by 20 pm .
  • the reflective element 5 vertically extends beyond the light emission surface 4 by 20 pm .
  • the optoelectronic device according to the exemplary embodiment in Figure 5 has a reflective element 5 proj ecting above the light emission surface 4 by 100 pm . Accordingly, electromagnetic radiation 10 (not shown) emitted by the light emitting semiconductor chip 2 is incident on the reflective element 5 already at smaller emission angles a compared to the optoelectronic device described in connection with Figure 4 .
  • Figure 6 shows an optoelectronic device according to a further exemplary embodiment . Compared to the optoelectronic device described in connection with Figure 4 , the optoelectronic device shown in Figure 6 further comprises a second lens 9 .
  • the second lens 9 is a lens on a chip . In other words , the second lens is arranged directly on the light emission surface 4 of the light emitting semiconductor chip 2 .
  • the second lens 9 is configured to increase the light extraction in vertical direction V .
  • the second lens 9 comprises an ultra-high refractive index silicone forming an overcast profile above the light emission surface 4 .
  • the second lens 9 extends in lateral direction L between sidewalls of the dam formed by the reflective element 5 .
  • the reflective element 5 functions as a stopping point for the overcast profile . Accordingly, a shape and a thickness of the overcast profile in vertical direction V is easier to control .
  • Figure 7 shows a plan view of an optoelectronic device according to an exemplary embodiment .
  • a plan view of a main surface 11 of a carrier 1 is shown .
  • a light emitting semiconductor chip 2 is arranged at the center of the main surface 11 .
  • a reflective encapsulation 3 is disposed on the main surface 11 , such that the light emission surface 4 of the light emitting semiconductor chip 2 remains free of the reflective encapsulation 3 .
  • a reflective element 5 forming a dam that completely surrounds the light emitting semiconductor chip 2 is disposed on the reflective encapsulation 3 .
  • the reflective element 5 partially covers bond wires 7 .
  • the reflective element 5 and the reflective encapsulation 3 both comprise a silicone with a powder of TiC particles embedded therein .
  • the optoelectronic device according to the exemplary embodiment shown in Figure 8 further comprises a second lens 9 .
  • the second lens 9 is directly disposed on the light emission surface 4 of the light emitting semiconductor chip 2 .
  • Figure 9 shows an optoelectronic device according to an exemplary embodiment .
  • the optoelectronic device further comprises a housing 13 and a transparent window 14 forming a cavity 15 .
  • the carrier 1 including the light emitting semiconductor chip 2 is arranged on a mounting surface 16 of the housing 13 inside the cavity 15 .
  • Electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 is coupled out of the optoelectronic device through the transparent window 14 .
  • the reflective element 5 is arranged such that electromagnetic radiation 10 emitted at large emission angles a is not incident on the housing 13 , where it may be absorbed .
  • the reflective element 5 deflects this electromagnetic radiation 10 to smaller emission angles a, such that it can exit through the transparent window 14 .
  • an ef ficiency of the optoelectronic device is advantageously increased .
  • Figure 10 describes di f ferent steps of a method for producing an optoelectronic device according to an exemplary embodiment .
  • a carrier 1 is provided in a first step 21 .
  • a light emitting semiconductor chip 2 is arranged on the carrier 1 and electrically connected to contact pads 6 on the carrier 1 .
  • a reflective encapsulation 3 is disposed on the carrier 1 such that a light emission surface 4 of the light emitting semiconductor chip 2 remains free of the reflective encapsulation 3 .
  • the reflective encapsulation 3 comprises a low viscosity silicone mixed with a TiCp filler .
  • a subsequent third step 23 the reflective encapsulation 3 is cured and thereby hardened, for example by applying heat in an oven .
  • a reflective element 5 is disposed on the reflective encapsulation 3 .
  • the reflective element 5 comprises a high viscosity silicone mixed with a TiC filler .
  • the reflective element 5 is disposed such that it forms a reflective dam completely surrounding the light emitting semiconductor chip 2 in lateral directions L .
  • the reflective element 5 extends in vertical direction V by approximately 100 pm beyond the light emitting semiconductor chip 2 .
  • the reflective element 5 is cured and thereby hardened in a fi fth step 25 .
  • a high viscosity ultra-high refractive index silicone is dispensed to fill up the dam formed by the reflective element 5 with an overcast profile .
  • the overcast profile forms the second lens 9 and is directly arranged on the light emission surface 4 of the light emitting semiconductor chip 2 .
  • the overcast profile is cured subsequently in a seventh step 27 .
  • the first lens 8 is molded over the carrier 1 , the light emitting semiconductor chip 2 , the reflective encapsulation 3 , the reflective element 5 and the second lens 9 .

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Power Engineering (AREA)
  • Led Device Packages (AREA)

Abstract

An optoelectronic device is specified, comprising: - a carrier (1), - a light emitting semiconductor chip (2) arranged on the carrier (1), - a reflective encapsulation (3) disposed on the carrier (1), covering at least parts of the carrier (1) and at least parts of the light emitting semiconductor chip (2), such that a light emission surface (4) of the light emitting semiconductor chip (2) remains free of the reflective encapsulation(3), and - a reflective element (5) disposed on the reflective encapsulation (3), wherein - the reflective element (5) completely surrounds the light emitting semiconductor chip (2). Further, a method for producing an optoelectronic device is specified.

Description

Description
OPTOELECTRONIC DEVICE AND METHOD FOR PRODUCING AN OPTOELECTRONIC DEVICE
An optoelectronic device and a method for producing an optoelectronic device are speci fied herein .
At least one obj ect of certain embodiments is to speci fy an optoelectronic device with an increased ef ficiency .
At least one obj ect of certain embodiments is to speci fy a method for producing an optoelectronic device with an increased ef ficiency .
According to at least one embodiment , the optoelectronic device comprises a carrier . In particular, the carrier is configured for a mechanical stabili zation of the optoelectronic device . The carrier may be configured to dissipate heat generated during operation of the optoelectronic device . For example , the carrier comprises a ceramic material or a metal , or consists of a ceramic material or a metal .
The carrier comprises a main surface extending in lateral directions . A direction perpendicular to the main surface of the carrier is denoted as a vertical direction in the following . In particular, the vertical direction is perpendicular to the lateral directions .
According to at least one embodiment , the optoelectronic device comprises a light emitting semiconductor chip arranged on the carrier . In particular, the light emitting semiconductor chip is arranged on the main surface of the carrier . Preferably, a light emission surface of the light emitting semiconductor chip faces away from the carrier . For example , the light emission surface extends in lateral directions . In other words , the light emission surface is parallel to the main surface of the carrier . A direction normal to the light emission surface is thus parallel to the vertical direction .
The light emitting semiconductor chip is configured to emit electromagnetic radiation in a spectral range between infrared light and ultraviolet light , for example . Electromagnetic radiation generated during operation is partly emitted in the vertical direction via the light emission surface of the light emitting semiconductor chip . In particular, electromagnetic radiation is emitted in a range of emission angles . For example , the light emitting semiconductor chip emits electromagnetic radiation in a range of emission angles following a Lambertian emission pattern .
Here and in the following an emission angle denotes an angle between the vertical direction and an emission direction of electromagnetic radiation emitted by the light emitting semiconductor chip . For example , electromagnetic radiation is partly emitted at an emission angle of 0 ° . At least a part of the electromagnetic radiation generated during operation may be emitted at emission angles between 0 ° and 90 ° , inclusive . An emission angle of 90 ° corresponds to a lateral emission direction . Moreover, at least a part of the electromagnetic radiation generated during operation may be emitted at emission angles larger than 90 ° . For example , at least a part of the electromagnetic radiation generated during operation may be emitted via side faces of the light emitting semiconductor chip .
Preferably, the light emitting semiconductor chip comprises a light emitting diode or is formed as a light emitting diode . In particular, the light emitting diode comprises a semiconductor layer stack . The semiconductor layer stack further comprises an active region configured for generating electromagnetic radiation during operation of the light emitting semiconductor chip . For example , the active region comprises a pn-j unction .
The semiconductor stack preferably comprises a I I I /V compound semiconductor material . A I I I /V compound semiconductor material comprises at least one element from the third main group, such as B, Al , Ga, In, and one element from the fi fth main group, for example N, P, As . In particular, the term " I I I /V compound semiconductor material" includes the group of binary, ternary or quaternary compounds containing at least one element from the third main group and at least one element from the fi fth main group . Moreover, the I I I /V semiconductor material may comprise one or more dopants .
For example , the light emitting semiconductor chip may further comprise a light conversion element . In particular, the light conversion element comprises a phosphor configured for converting the electromagnetic radiation generated in the active region . The phosphor may be configured to convert electromagnetic radiation in a first spectral range into electromagnetic radiation in a second spectral range . For example , the phosphor converts blue light into red and/or green and/or yellow light . The optoelectronic device emits then, for example , white light mixed from the converted light and the electromagnetic radiation generated in the active region .
According to at least one embodiment , the optoelectronic device comprises a reflective encapsulation disposed on the carrier . The reflective encapsulation covers at least parts of the carrier and at least parts of the light emitting semiconductor chip, such that the light emission surface of the light emitting semiconductor chip remains free of the reflective encapsulation . For example , the reflective encapsulation at least partially covers side faces of the light emitting semiconductor chip . In particular, side faces extend in vertical direction and/or are arranged perpendicular or inclined to the light emission surface of the light emitting semiconductor chip .
In particular, the reflective encapsulation is configured to deflect electromagnetic radiation emitted by the light emitting semiconductor chip at emission angles larger than 90 ° . For example , electromagnetic radiation at emission angles larger than 90 ° is deflected to emission angles smaller than 90 ° . The reflective encapsulation reflects at least 50% of the incident electromagnetic radiation, for example . Preferably, the reflective encapsulation reflects at least 80% of the incident electromagnetic radiation .
For example , the reflective encapsulation comprises a matrix material and a filler material . The matrix material may comprise a resin, such as a silicone resin or an epoxy resin, for example . In particular, the filler material is a powder of small light-reflective particles embedded in the matrix material . Preferably, the filler material comprises a light- reflective oxide , such as titanium dioxide , for example . According to at least one embodiment , the optoelectronic device comprises a reflective element disposed on the reflective encapsulation, wherein the reflective element completely surrounds the light emitting semiconductor chip in lateral directions . In particular, the reflective element is configured to deflect electromagnetic radiation emitted by the light emitting semiconductor chip at emission angles larger than or equal to 90 ° . Electromagnetic radiation incident on the reflective element is deflected due to specular reflection or di f fuse reflection by the reflective element , for example .
Preferably, the reflective element is configured to deflect electromagnetic radiation emitted by the light emitting semiconductor chip at emission angles larger than or equal to 70 ° . For example , the reflective element deflects electromagnetic radiation into a range of emission angles between 0 ° and 70 ° , inclusive .
For example , the reflective element is formed as a dam that completely surrounds the light emitting semiconductor chip in lateral directions . In particular, the reflective element is not in direct contact with the light emitting semiconductor chip . For example , a gap is arranged between the reflective element and the light emitting semiconductor chip .
For example , the reflective element is in direct contact with the reflective encapsulation . It is in particular possible that there is no direct contact between the carrier and the reflective element . In this case the reflective element is , for example , connected and attached exclusively to the reflective encapsulation . The reflective element deflects at least 50% of the incident electromagnetic radiation, for example . Preferably, the reflective element deflects at least 80% of the incident electromagnetic radiation .
According to a preferred embodiment , the optoelectronic device comprises :
- a carrier,
- a light emitting semiconductor chip arranged on the carrier,
- a reflective encapsulation disposed on the carrier, covering at least parts of the carrier and at least parts of the light emitting semiconductor chip, such that a light emission surface of the light emitting semiconductor chip remains free of the reflective encapsulation, and
- a reflective element disposed on the reflective encapsulation, wherein
- the reflective element completely surrounds the light emitting semiconductor chip in lateral directions .
The optoelectronic device described herein is based on the idea that the reflective element disposed on the reflective encapsulation increases a light extraction and therefore an ef ficiency of the optoelectronic device .
For example , the optoelectronic device may comprise a lens configured for directing electromagnetic radiation from the light emitting semiconductor chip to an application . One problem is that electromagnetic radiation emitted at large emission angles , for example emission angles larger than 70 ° , may not be coupled into the lens i f the reflective element is not present . For example , electromagnetic radiation emitted at emission angles larger than 70 ° may be directed at a fixture , such as a housing, that may have a low reflectivity . Moreover, electromagnetic radiation emitted at large emission angles may be trapped in the optoelectronic device , for example . Accordingly, electromagnetic radiation emitted by the light emitting semiconductor chip at large emission angles may be wasted, thereby decreasing an ef ficiency of the optoelectronic device without a reflective element .
In particular, the reflective element described herein may be configured to deflect electromagnetic radiation emitted from the light emitting semiconductor chip at large emission angles , for example larger than approximately 70 ° , to smaller emission angles , for example smaller than 70 ° .
An optoelectronic device without the reflective element may radiate approximately 6% of the electromagnetic radiation generated by the light emitting semiconductor chip at emission angles larger than 70 ° , for example . This electromagnetic radiation may not be usable for applications and thus may be wasted . The reflective element is configured to redirect this electromagnetic radiation into a range of emission angles smaller than 70 ° , for example , such that it is usable in applications , thereby increasing the ef ficiency of the optoelectronic device by up to 6% , for example .
According to at least one embodiment of the optoelectronic device , the carrier comprises an electrical contact pad for electrically contacting the light emitting semiconductor chip, and the electrical contact pad is at least partially covered by the reflective encapsulation . In particular, the electrical contact pad is configured to provide external electrical energy to the light emitting semiconductor chip . According to at least one embodiment of the optoelectronic device , the light emitting semiconductor chip is electrically connected to the electrical contact pad via a bond wire , and the reflective element at least partially covers the bond wire . Moreover, the reflective encapsulation is arranged such that it partially covers the contact pad and the bond wire , for example .
The light emitting semiconductor chip may be electrically connected to two separate contact pads via two separate bond wires , for example . In particular, the bond wires are connected to electrical contacts on the light emission surface of the light emitting semiconductor chip . For example , the light emitting semiconductor chip is a flip-chip with electrical contacts on the light emission surface facing away from the carrier .
Alternatively and/or in addition, the light emitting semiconductor chip may be directly arranged on the electrical contact pad . For example , the light emitting semiconductor chip is a flip-chip with electrical contacts on a side facing the carrier . In other words , the electrical contacts of the light emitting semiconductor chip are arranged on a surface opposite to the light emission surface . In particular, the electrical contacts of the flip-chip are directly soldered onto the electrical contact pads on the carrier .
According to at least one embodiment of the optoelectronic device , a thickness of the reflective encapsulation decreases with increasing distance from the light emitting semiconductor chip . Here and in the following the thickness refers to a spatial extension in vertical direction . In particular, the thickness of the reflective encapsulation decreases with increasing distance in lateral direction from the light emitting semiconductor chip . For example , the matrix material of the reflective encapsulation adheres to side faces of the light emitting semiconductor chip and therefore has a larger thickness in the vicinity of the light emitting semiconductor chip .
According to at least one embodiment of the optoelectronic device , the reflective element completely proj ects above the light emitting semiconductor chip in a direction perpendicular to the light emission surface by not more than 100 pm . In other words , the reflective element extends in vertical direction beyond the light emitting semiconductor chip . Moreover, the reflective element preferably extends in vertical direction beyond the light emitting semiconductor chip by not more than 100 pm .
Alternatively and/or in addition, the reflective element proj ects above the light emitting semiconductor chip such that electromagnetic radiation emitted by the light emitting semiconductor chip at emission angles larger than 70 ° is incident on the reflective element and thus deflected by the reflective element .
According to at least one embodiment of the optoelectronic device , the reflective element comprises a matrix material with an oxide filler . The matrix material comprises a resin, such as a silicone or an epoxy resin, for example . The oxide filler preferably comprises a powder of reflective particles comprising an oxide , for example titanium dioxide . The reflective particles are configured to reflect or deflect electromagnetic radiation emitted by the light emitting semiconductor chip during operation . Preferably, the reflective particles have a reflectivity of more than 80% for electromagnetic radiation emitted by the light emitting semiconductor chip .
The reflective element may be directly disposed on the reflective encapsulation . Preferably, the matrix material of the reflective encapsulation and the matrix material of the reflective element are from the same material family . For example , both matrix materials comprise silicone . Advantageously, a risk of delamination is thereby reduced .
According to at least one embodiment of the optoelectronic device , the reflective element comprises a frame adhesively connected to the reflective encapsulation . For example , the reflective element is a preformed frame , such as a molded frame . In particular, the frame is glued onto the reflective encapsulation . For example , the frame has flat reflective surfaces configured to reflect incident electromagnetic radiation into a predetermined range of emission angles . Advantageously, this allows to adj ust and/or tune an emission characteristic of the optoelectronic device .
According to at least one embodiment , the optoelectronic device comprises a first lens arranged above the light emission surface of the light emitting semiconductor chip . In particular, the first lens is configured to increase an extraction of electromagnetic radiation emitted by the light emitting semiconductor chip . In other words , the first lens is configured to redirect electromagnetic radiation emitted by the light emitting semiconductor chip at large emission angles to smaller emission angles . In particular, the first lens is configured to increase an intensity of electromagnetic radiation emitted in vertical direction .
According to at least one embodiment of the optoelectronic device , the first lens completely covers the carrier in a top view of the optoelectronic device . For example , the first lens is molded over the light emitting semiconductor chip and the carrier . In particular, the first lens is a hal f- spherical lens configured for an improved light extraction from the optoelectronic device .
According to at least one embodiment , the optoelectronic device further comprises a second lens disposed directly on the light emission surface of the light emitting semiconductor chip, such that the second lens is arranged between the light emitting semiconductor chip and the first lens . For example , the second lens is configured to improve the light extraction from the light emitting semiconductor chip . The second lens comprises an ultra-high refractive index silicone , for example . In particular, the refractive index of the ultra-high refractive index silicone is at least 1 , 6 .
Further, a method for producing an optoelectronic device is speci fied . In particular, the method is configured to produce an optoelectronic device as speci fied herein . All features of the optoelectronic device are also speci fied for the method for producing an optoelectronic device and vice versa .
According to at least one embodiment of the method for producing an optoelectronic device , a light emitting semiconductor chip mounted on a carrier is provided . In particular, the light emitting semiconductor chip is glued and/or soldered onto a main surface of the carrier . Preferably, the light emitting semiconductor chip is electrically connected to electrical contact pads on the main surface of the carrier .
According to at least one embodiment of the method for producing an optoelectronic device , a reflective encapsulation is disposed on the carrier, covering at least parts of the carrier and at least parts of the light emitting semiconductor chip, such that a light emission surface of the light emitting semiconductor chip remains free of the reflective encapsulation . For example , the reflective encapsulation comprises a resin that is applied to the main surface of the carrier . The reflective encapsulation may be applied via dispensing or printing, for example . In particular, the reflective encapsulation is applied such that side surfaces of the light emitting semiconductor chip are at least partially covered by the reflective encapsulation .
According to at least one embodiment of the method for producing an optoelectronic device , a reflective element is disposed on the reflective encapsulation . For example , the reflective element comprises a high viscosity silicone . In particular, the high viscosity silicone is applied around the semiconductor chip, such that it forms a dam . Preferably, the viscosity is large enough such that the form of the dam remains relatively stable until the high viscosity silicone or the high viscosity resin is cured . In particular, the reflective element proj ects above the light emitting semiconductor chip in a vertical direction .
According to at least one embodiment of the method for producing an optoelectronic device , the reflective encapsulation and the reflective element comprise di f ferent resins , and before curing the resin of the reflective encapsulation has lower viscosity than the resin of the reflective element . In particular, the viscosity of the resin of the reflective element is large enough such that a dam can be formed and its shape remains substantially stable until the resin is cured .
According to at least one embodiment of the method for producing an optoelectronic device , the resin of the reflective encapsulation is at least partially cured before the resin of the reflective element is disposed directly on the reflective encapsulation . In particular, the resin of the reflective encapsulation is at least partially cured such that it forms a relatively stable surface upon which the resin of the reflective element can be disposed .
Preferably, the reflective element comprises a matrix material from the same or a similar material family as the matrix material of the reflective encapsulation . For example , both matrix materials comprise a silicone . Therefore , mechanically stable chemical bonds may form between the reflective element and the reflective encapsulation upon full curing of the matrix materials . Accordingly, a risk of delamination is advantageously decreased .
According to at least one embodiment of the method for producing an optoelectronic device , the reflective element comprises a molded frame and is adhesively glued onto the reflective encapsulation .
According to at least one embodiment of the method for producing an optoelectronic device , a first lens is molded over the carrier, the light emitting semiconductor chip, the reflective encapsulation, and the reflective element . In particular, the first lens is a hal f-spherical lens . The first lens comprises a silicone , for example .
According to at least one embodiment of the method for producing an optoelectronic device , a second lens is disposed directly on the light emission surface of the light emitting semiconductor chip before the first lens is molded over the carrier and the light emitting semiconductor chip . The second lens comprises an ultra-high refractive index silicone , for example . In particular, the ultra-high refractive index silicone is dispensed inside the dam formed by the reflective element such that it forms an overcast profile on the light emission surface . For example , the dam forms a stopping point for the overcast profile . Advantageously, the stopping point allows for an easier control of the thickness and a shape of the overcast profile .
Further advantageous embodiments and further embodiments of the optoelectronic device and the method for producing an optoelectronic device will become apparent from the following exemplary embodiments described in connection with the figures .
Figures 1 and 2 show schematic cross-sections of an optoelectronic device according to an exemplary embodiment .
Figure 3 to 6 show schematic cross-sections of optoelectronic devices according to further exemplary embodiments .
Figures 7 and 8 show schematic plan views of optoelectronic devices according to di f ferent exemplary embodiments . Figure 9 shows a schematic cross-section of an optoelectronic device according to a further exemplary embodiment .
Figure 10 shows a flow diagram with steps of a method for producing an optoelectronic device according to an exemplary embodiment .
Elements that are identical , similar, or have the same ef fect , are denoted by the same reference signs in the figures . The figures and the proportions of the elements shown in the figures are not to be regarded as true to scale . Rather, individual elements , in particular layer thicknesses may be shown exaggeratedly large for better representability and/or better understanding .
The optoelectronic device according to the exemplary embodiment in Figure 1 comprises a carrier 1 with a main surface 11 extending in lateral directions L . A light emitting semiconductor chip 2 is arranged on the main surface 11 . In particular, the carrier comprises 1 a ceramic material and the light emitting semiconductor chip 2 is a light emitting diode .
The light emitting semiconductor chip 2 is electrically connected to electrical contact pads 6 on the main surface 11 of the carrier 1 . A bond wire 7 electrically connects the light emitting semiconductor chip 2 to an electrical contact pad 6 . Moreover, the light emitting semiconductor chip 2 is directly soldered onto a further electrical contact pad 6 .
The light emitting semiconductor chip 2 has a light emission surface 4 on a side facing away from the carrier 1 . Electromagnetic radiation 10 (not shown, see Figure 2 ) emitted by the light emitting semiconductor chip 2 during operation is primarily emitted through the light emission surface 4 . A part of the electromagnetic radiation 10 may be emitted through side faces of the light emitting semiconductor chip 2 .
A reflective encapsulation 3 is disposed on the main surface 11 of the carrier 1 . The reflective encapsulation 3 at least partially covers side faces of the light emitting semiconductor chip 2 . Moreover, the reflective encapsulation 3 at least partially covers the electrical contact pads 6 . A thickness D of the reflective encapsulation decreases with increasing lateral distance from the light emitting semiconductor chip 2 .
The reflective encapsulation 3 is configured to reflect at least parts of the electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 in a direction towards the main surface 11 of the carrier 1 . For example , the reflective encapsulation 3 redirects the electromagnetic radiation 10 towards a vertical direction V . Therefore , the reflective encapsulation 3 increases a light extraction in the vertical direction V .
The reflective encapsulation 3 comprises a matrix material and an oxide filler . The matrix material comprises a silicone , and the oxide filler comprises a powder of titanium dioxide particles . The reflective encapsulation 3 reflects at least 80% of the incident electromagnetic radiation 10 generated by the light emitting semiconductor chip 2 during operation . A reflective element 5 is disposed on the reflective encapsulation 3 and completely surrounds the light emitting semiconductor chip 2 in lateral directions L . The reflective element 5 proj ects above the light emission surface 4 of the light emitting semiconductor chip 2 . In other words , the reflective element 5 extends beyond the light emitting semiconductor chip 2 in vertical direction V . The bond wire 7 is partially covered by the reflective element 5 .
The reflective element 5 is configured to deflect at least parts of the electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 in lateral direction L, for example . In particular, the electromagnetic radiation 10 is deflected towards the vertical direction V . The reflective element 5 deflects at least 80% of the incident electromagnetic radiation 10 generated by the light emitting semiconductor chip 2 during operation . Therefore , the reflective element 5 increases the light extraction and thus an ef ficiency of the optoelectronic device .
The reflective element 5 comprises a matrix material and an oxide filler . The matrix material is a resin, for example a silicone . Preferably, the matrix material of the reflective element 5 is from the same material family as the matrix material of the reflective encapsulation 3 . For example , both matrix materials comprise a silicone . Therefore , mechanically stable bonds may form between the reflective encapsulation 3 and the reflective element 5 upon curing of the matrix materials . Accordingly, a risk of delamination is advantageously reduced .
The optoelectronic device further comprises a first lens 8 completely covering the main surface 11 of the carrier 1 in a top view along the vertical direction V . The first lens 8 is arranged above the light emitting semiconductor chip 2 , the reflective encapsulation 3 , the reflective element 5 and the carrier 1 . The first lens 8 is a hal f-spherical , molded lens configured to enhance the light extraction and thus the ef ficiency of the optoelectronic device .
Figure 2 shows a schematic cross-section of an optoelectronic device according to the exemplary embodiment described in connection with Figure 1 . In particular, Figure 2 schematically shows electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 during operation .
The electromagnetic radiation 10 is emitted in a range of emission angles a between 0 ° and more than 90 ° , for example . The emission angle a denotes an angle between the vertical direction and an emission direction of the electromagnetic radiation 10 .
The reflective element 5 proj ects above the light emitting semiconductor chip 2 such that electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 at emission angles a larger than 70 ° is incident on the reflective element 5 . The reflective element 5 deflects the electromagnetic radiation 10 into a range of emission angles a smaller than or equal to 70 ° , thereby increasing the light extraction and thus the ef ficiency of the optoelectronic device .
Figure 3 shows a schematic cross-section of an optoelectronic device according to a further exemplary embodiment . In contrast to the exemplary embodiment described in connection with Figure 1 , the reflective element 5 comprises a molded frame 12 that is arranged on the reflective encapsulation 3 . In particular, the molded frame 12 is glued onto a top surface of the reflective encapsulation 3 .
The molded frame 12 completely surrounds the light emitting semiconductor chip 2 in lateral directions L and completely proj ects above the light emission surface 4 of the light emitting semiconductor chip 2 in vertical direction V . Advantageously, reflective surfaces of the molded frame 12 are configured such that incident electromagnetic radiation 10 is deflected by the molded frame 12 into a predetermined range of emission angles a . For example , the molded frame deflects light emitted at emission angles a of at least 70 ° into a range of emission angles a between 0 ° and 20 ° , inclusive .
Figure 4 shows a schematic cross-section of an optoelectronic device according to a further exemplary embodiment . In contrast to the exemplary embodiment described in connection with Figure 1 , the reflective element 5 does not cover the bond wires 7 . Moreover, the reflective element 5 proj ects above the light emission surface 4 of the light emitting semiconductor chip 2 by 20 pm . In other words , the reflective element 5 vertically extends beyond the light emission surface 4 by 20 pm .
In contrast to Figure 4 , the optoelectronic device according to the exemplary embodiment in Figure 5 has a reflective element 5 proj ecting above the light emission surface 4 by 100 pm . Accordingly, electromagnetic radiation 10 (not shown) emitted by the light emitting semiconductor chip 2 is incident on the reflective element 5 already at smaller emission angles a compared to the optoelectronic device described in connection with Figure 4 . Figure 6 shows an optoelectronic device according to a further exemplary embodiment . Compared to the optoelectronic device described in connection with Figure 4 , the optoelectronic device shown in Figure 6 further comprises a second lens 9 . The second lens 9 is a lens on a chip . In other words , the second lens is arranged directly on the light emission surface 4 of the light emitting semiconductor chip 2 . The second lens 9 is configured to increase the light extraction in vertical direction V .
The second lens 9 comprises an ultra-high refractive index silicone forming an overcast profile above the light emission surface 4 . The second lens 9 extends in lateral direction L between sidewalls of the dam formed by the reflective element 5 . The reflective element 5 functions as a stopping point for the overcast profile . Accordingly, a shape and a thickness of the overcast profile in vertical direction V is easier to control .
Figure 7 shows a plan view of an optoelectronic device according to an exemplary embodiment . In particular, a plan view of a main surface 11 of a carrier 1 is shown . A light emitting semiconductor chip 2 is arranged at the center of the main surface 11 . A reflective encapsulation 3 is disposed on the main surface 11 , such that the light emission surface 4 of the light emitting semiconductor chip 2 remains free of the reflective encapsulation 3 .
A reflective element 5 forming a dam that completely surrounds the light emitting semiconductor chip 2 is disposed on the reflective encapsulation 3 . The reflective element 5 partially covers bond wires 7 . The reflective element 5 and the reflective encapsulation 3 both comprise a silicone with a powder of TiC particles embedded therein .
Compared to the optoelectronic device described in connection with Figure 7 , the optoelectronic device according to the exemplary embodiment shown in Figure 8 further comprises a second lens 9 . The second lens 9 is directly disposed on the light emission surface 4 of the light emitting semiconductor chip 2 .
Figure 9 shows an optoelectronic device according to an exemplary embodiment . In addition to the optoelectronic device described in connection with Figure 3 , the optoelectronic device further comprises a housing 13 and a transparent window 14 forming a cavity 15 . The carrier 1 including the light emitting semiconductor chip 2 is arranged on a mounting surface 16 of the housing 13 inside the cavity 15 .
Electromagnetic radiation 10 emitted by the light emitting semiconductor chip 2 is coupled out of the optoelectronic device through the transparent window 14 . The reflective element 5 is arranged such that electromagnetic radiation 10 emitted at large emission angles a is not incident on the housing 13 , where it may be absorbed . In particular, the reflective element 5 deflects this electromagnetic radiation 10 to smaller emission angles a, such that it can exit through the transparent window 14 . Thereby an ef ficiency of the optoelectronic device is advantageously increased .
Figure 10 describes di f ferent steps of a method for producing an optoelectronic device according to an exemplary embodiment . In a first step 21 a carrier 1 is provided . Moreover, a light emitting semiconductor chip 2 is arranged on the carrier 1 and electrically connected to contact pads 6 on the carrier 1 .
In a second step 22 a reflective encapsulation 3 is disposed on the carrier 1 such that a light emission surface 4 of the light emitting semiconductor chip 2 remains free of the reflective encapsulation 3 . The reflective encapsulation 3 comprises a low viscosity silicone mixed with a TiCp filler .
In a subsequent third step 23 the reflective encapsulation 3 is cured and thereby hardened, for example by applying heat in an oven .
In a fourth step 24 a reflective element 5 is disposed on the reflective encapsulation 3 . The reflective element 5 comprises a high viscosity silicone mixed with a TiC filler . In particular, the reflective element 5 is disposed such that it forms a reflective dam completely surrounding the light emitting semiconductor chip 2 in lateral directions L . Moreover, the reflective element 5 extends in vertical direction V by approximately 100 pm beyond the light emitting semiconductor chip 2 . Subsequently, the reflective element 5 is cured and thereby hardened in a fi fth step 25 .
In a sixth step 26 a high viscosity ultra-high refractive index silicone is dispensed to fill up the dam formed by the reflective element 5 with an overcast profile . The overcast profile forms the second lens 9 and is directly arranged on the light emission surface 4 of the light emitting semiconductor chip 2 . The overcast profile is cured subsequently in a seventh step 27 . In an eighth step 28 the first lens 8 is molded over the carrier 1 , the light emitting semiconductor chip 2 , the reflective encapsulation 3 , the reflective element 5 and the second lens 9 .
This patent application claims the priority of German patent application DE 102022113097 . 5 , the disclosure content of which is hereby incorporated by reference . The invention is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments . Rather, the invention encompasses any new feature and also any combination of features , which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments , even i f this feature or this combination itsel f is not explicitly speci fied in the patent claims or exemplary embodiments .
Reference numerals :
1 carrier
2 light emitting semiconductor chip
3 reflective encapsulation
4 light emission surface
5 reflective element
6 electrical contact pad
7 bond wire
8 first lens
9 second lens
10 electromagnetic radiation
11 main surface
12 molded frame
13 housing
14 transparent window
15 cavity
16 mounting surface
21 first step
22 second step
23 third step
24 fourth step
25 fi fth step
26 sixth step
27 seventh step
28 eighth step a emission angle
D thickness
V vertical direction
L lateral direction

Claims

Claims
1. Optoelectronic device comprising,
- a carrier ( 1 ) ,
- a light emitting semiconductor chip (2) arranged on the carrier ( 1 ) ,
- a reflective encapsulation (3) disposed on the carrier (1) , covering at least parts of the carrier (1) and at least parts of the light emitting semiconductor chip (2) , such that a light emission surface (4) of the light emitting semiconductor chip (2) remains free of the reflective encapsulation ( 3 ) , and
- a reflective element (5) disposed on the reflective encapsulation (3) , wherein
- the reflective element (5) completely surrounds the light emitting semiconductor chip (2) in lateral directions.
2. Optoelectronic device according to claim 1, wherein
- the carrier (1) comprises an electrical contact pad (6) for electrically contacting the light emitting semiconductor chip ( 2 ) , and
- the electrical contact pad (6) is at least partially covered by the reflective encapsulation (3) .
3. Optoelectronic device according to the previous claim, wherein
- the light emitting semiconductor chip (2) is electrically connected to the electrical contact pad (6) via a bond wire ( 7 ) , and
- the reflective element (5) at least partially covers the bond wire ( 7 ) .
4. Optoelectronic device according to any of the previous claims, wherein a thickness (D) of the reflective encapsulation (3) decreases with increasing distance from the light emitting semiconductor chip (2) .
5. Optoelectronic device according to any of the previous claims, wherein the reflective element (5) completely projects above the light emitting semiconductor chip (2) in a direction perpendicular to the light emission surface (4) by not more than 100 micrometers.
6. Optoelectronic device according to any of the previous claims, wherein the reflective element (5) comprises a matrix material with an oxide filler.
7. Optoelectronic device according to any of the previous claims, wherein the reflective element (5) comprises a frame adhesively connected to the reflective encapsulation (3) .
8. Optoelectronic device according to any of the previous claims, further comprising a first lens (8) arranged above the light emission surface (4) of the light emitting semiconductor chip (2) .
9. Optoelectronic device according to the previous claim, wherein the first lens (8) completely covers the carrier (1) in a top view of the optoelectronic device.
10. Optoelectronic device according to one of claims 8 or 9, further comprising a second lens (9) disposed directly on the light emission surface (4) of the light emitting semiconductor chip (2) , such that the second lens (9) is arranged between the light emitting semiconductor chip (2) and the first lens (8) .
11. Method for producing an optoelectronic device, comprising the steps:
- providing a light emitting semiconductor chip (2) mounted on a carrier ( 1 ) ,
- disposing a reflective encapsulation (3) on the carrier (1) , covering at least parts of the carrier (1) and at least parts of the light emitting semiconductor chip (2) , such that a light emission surface (4) of the light emitting semiconductor chip (2) remains free of the reflective encapsulation, and
- disposing a reflective element (5) on the reflective encapsulation (3) , wherein
- the reflective element (5) completely surrounds the light emitting semiconductor chip (2) .
12. Method according to the previous claim, wherein
- the reflective encapsulation (3) and the reflective element (5) comprise different resins, and
- before curing, the resin of the reflective encapsulation (3) has a lower viscosity than the resin of the reflective element (5) .
13. Method according to the previous claim, wherein the resin of the reflective encapsulation (3) is at least partially cured before the resin of the reflective element
(5) is disposed directly on the reflective encapsulation (3) .
14. Method according to claim 11, wherein the reflective element (5) comprises a molded frame and is adhesively glued onto the reflective encapsulation (3) .
15. Method according to any of claims 10 to 13, wherein a first lens (8) is molded over the carrier (1) , the light emitting semiconductor chip (2) , the reflective encapsulation (3) , and the reflective element (5) .
PCT/EP2023/061247 2022-05-24 2023-04-28 Optoelectronic device and method for producing an optoelectronic device WO2023227324A1 (en)

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DE102022113097 2022-05-24

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