Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/81—Bodies
  • H10H20/819—Bodies characterised by their shape, e.g. curved or truncated substrates
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/81—Bodies
  • H10H20/819—Bodies characterised by their shape, e.g. curved or truncated substrates
  • H10H20/821—Bodies characterised by their shape, e.g. curved or truncated substrates of the light-emitting regions, e.g. non-planar junctions
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
  • H01L2224/42—Wire connectors; Manufacturing methods related thereto
  • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
  • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
  • H01L2224/4805—Shape
  • H01L2224/4809—Loop shape
  • H01L2224/48091—Arched

Definitions

• the invention relates to a radiation-emitting semiconductor chip with an active layer which comprises a radiation-generating zone and with transverse sides and longitudinal sides which laterally delimit the semiconductor in an extension direction of the active zone. Furthermore, the invention relates to one with such . Semiconductor chip formed luminescent diode.
• Such a semiconductor chip is from the article by Song Jae Lee and Seok Won Song “Efficiency Improvement in Light-Emitting Diodes Based on Geometrically Deformed Chips", SPIE Conference on Light-Emitting Diodes: Research, Manufacturing and Applications III, San Jose, California, January 1999, pages 237-248.
• the semiconductor body of a semiconductor chip described there has a lower cover layer, an active zone and an upper cover layer.
• the semiconductor chip is prismatic with a diamond as the base.
• the light rays emanating from the active zone strike at least a few total reflections on the side surfaces on a side surface at an angle which is smaller than the critical angle for the total reflection.
• the light output is essentially limited by the absorption in the semiconductor chip.
• the thickness of the semiconductor chip remains the same, however, this has the consequence that the side faces of the semiconductor chip appear from a light-generating luminous point of the active zone at a smaller solid angle. As a percentage, fewer light rays therefore strike the side surfaces of the semiconductor chip directly. In principle, this can be remedied by scaling the thickness of the semiconductor chip with the cross-sectional dimensions, because this would result in large side faces again. However, this is difficult for procedural reasons.
• substrates for example, are only commercially available with certain predetermined layer thicknesses.
• the object of the invention is to create a semiconductor chip suitable for high radiation powers with improved coupling-out of the radiation generated in the semiconductor chip. Furthermore, it is an object of the invention to provide an optical component with an improved radiation yield.
• This object is achieved in that at least one long side of the semiconductor chip, which serves as a coupling surface, is longer than one transverse side in the direction of extension of the active zone.
• the lateral cross section In order to obtain a semiconductor chip suitable for high light outputs, it is first necessary to choose the lateral cross section so large that the heat loss generated can be dissipated. Below the lateral cross section is the area of one that extends longitudinally to the active zone To understand cross-section. Especially in a material with low thermal conductivity, the lateral cross section should be chosen so large that the heat loss generated in the active zone can be dissipated.
• the ratio of cross-sectional area to the sum of the side areas can now be influenced.
• the ratio of cross-sectional area to the sum of the side areas can be reduced by lengthening the long sides with respect to the transverse sides. This makes the ratio of cross-sectional area to that
• a semiconductor chip whose long sides are longer with respect to the transverse sides, with the same cross-sectional area, has a better radiation yield than a semiconductor chip with sides of the same length.
• the active zone is located in an active layer which is arranged on a radiation-transparent substrate which tapers towards a base surface of the substrate opposite the active layer.
• the radiation emanating from the active layer and which passes through the radiation-transmissive substrate generally impinges on the beveled longitudinal sides at an angle which is smaller than the total reflection angle, an increase in the solid angle at which the side surfaces of seen from the active layer to a particularly high light output.
• Figure la and b is a schematic representation of a cross section and a longitudinal section through a semiconductor chip according to the invention
• FIGS. 1a and b show a schematic illustration of a cross section through a luminescence diode and a view of a luminescence diode which is equipped with the semiconductor chip from FIGS. 1a and b,
• FIGS. 1a and b show a schematic representation of a cross section through a further luminescence diode and a plan view of a further luminescence diode which is provided with the semiconductor chip from FIGS. 1a and b,
• FIG. 4 shows a schematic illustration of an enlarged top view of a semiconductor chip provided with a contact layer
• FIG. 5 shows a schematic illustration of a cross section through a further semiconductor chip
• FIG. 6 shows a schematic illustration of a cross section through a modified semiconductor chip
• the region of the long sides 6 formed by the substrate 3 appears from a radiation-emitting luminous point 7 of the active layer 2 at a solid angle ⁇ > ⁇ .
• This solid angle ⁇ > ⁇ is so large that all light rays emanating from the luminous point 7 and extending within the portion of the light exit cone 8 lying in the substrate 3 strike the longitudinal side 6 and are coupled out.
• the semiconductor chip 1 is shown in longitudinal section in FIG. 1b. From the illuminated point 7, the regions of the transverse sides 9 formed by the substrate 3 appear at a solid angle ⁇ q .
• the solid angle ⁇ q is significantly smaller than the solid angle ⁇ i at which the long sides 6 appear from the luminous point 7.
• ⁇ q is so small that a part of the outcouplable light rays running in the portion of the light decoupling cone lying in the substrate strikes the lower cover layer 4 and is not decoupled.
• the thickness of the substrate 3 is in principle possible to increase the thickness of the substrate 3 to such an extent that all light rays within the light exit cone 8 strike the transverse sides 9. For practical reasons, however, this is only possible to a limited extent. This is because the commercially available substrates 3 are only available in certain predetermined thicknesses. The thickness of the substrate 3 can therefore not be chosen arbitrarily. It is therefore advantageous if the long sides 6 are chosen to be as long as possible.
• the transverse sides 9 should also be selected at least so short that the light rays emanating from a luminous point which is furthest away from a long side 6 in the light exit cone 8 strike this long side 6 directly.
• the enlargement of the long sides 6 in relation to the transverse sides 9 results in a favorable ratio of side surfaces to active surface.
• active area is understood to mean the area of active layer 2. With the same active area, the ratio of side areas to active area is same length of the long sides 6 and the transverse sides 9 greater than with the same length of the long sides 6 and the transverse
• FIGS. 2a and b each show a cross section and a top view of a luminescent diode component 10 equipped with the semiconductor chip 1.
• Partitions 11 arranged.
• the semiconductor chips 1 and the partition walls 11 are surrounded by a socket 12.
• Both the semiconductor chips 1 and the partition walls 11 and the holder 12 are arranged on a common carrier 13 and covered by a lens body 14 made, for example, of a plastic.
• the partition walls 11 and the holder 12 serve to deflect the radiation emitted by the semiconductor chips 1 in the lateral direction away from the carrier 13 into the lens body 14.
• the partition walls 11 in particular prevent the radiation emitted by one of the semiconductor chips 1 from being absorbed by one of the adjacent semiconductor chips 1.
• FIGS. 3a and 3b show a further exemplary embodiment of a luminescence diode component 5, in which the middle semiconductor chip is covered by a wide partition wall 16. is set, which has a contact surface 17 for bonding wires 18 on its upper side. The bond wires 18 lead from the contact area 17 to contact areas 19 on the semiconductor chips 1.
• the luminescence diode 15 In order to concentrate the radiation emitted by the semiconductor chips 1 in an emission direction facing away from the carrier 13, the luminescence diode 15 has a lens body 22 provided with two lenticular bulges 21, which covers the semiconductor chips 1.
• FIG. 4 shows an enlarged top view of one of the semiconductor chips 1 used in the luminescent diode component 10 or 15.
• the contact area 19 has a central connection area 23, for example a bonding area for a wire connection, from which there is a connection branch out contact tracks 24 with stub lines 25.
• the contact tracks 24 are designed like a frame. This configuration of the contact tracks 24 ensures a uniform distribution of the current over the active layer 2.
• the frame-like configuration of the contact tracks 24 along the circumference of the semiconductor chip 1 also avoids potential fluctuations.
• FIG. 5 shows a cross section through a further modified semiconductor chip 26.
• the semiconductor chip 26 here has a multilayer structure 27 which comprises the active layer 2.
• the multilayer structure 27 is applied to a radiation-transmissive substrate 3 and is on the side facing away from the substrate 3 from an upper
• Electrode 28 covered. Opposite this electrode 28, the substrate is provided with a lower electrode 29.
• the substrate 3 On the side adjoining the multilayer structure 27, the substrate 3 has beveled side surfaces 6, which enclose an inclination angle ⁇ with the normal of the multilayer structure 27. In the direction of the lower electrode 29 hen these sloping side faces into side faces arranged perpendicular to the multilayer structure 27 or to the active layer 2.
• the angle of inclination ⁇ of the tapered side surfaces 6 of the substrate 3 is preferably greater than the critical angle for an interface 31 formed by the multilayer structure 27 and the substrate 3 (the value of the critical angle is equal to the value of the total reflection angle for a transition from the substrate 3 into the multilayer structure 27).
• This shape substantially increases the solid angle of the light exit cone 8. Therefore, the enlargement of the longitudinal sides 6 in relation to the transverse sides 9 also has a particularly advantageous effect in the semiconductor chip 26 shown in FIG.
• the multilayer structure can be, for example, a GaN-based semiconductor structure.
• GaN, AIGaN, InGaN, InAlGaN are particularly suitable as semiconductor materials for this purpose.
• Such multilayer structures are generally produced using an epitaxial process.
• the multilayer structure 27 is preferably grown on a radiation-transmissive substrate, from which the substrate 3 for the semiconductor chip is also produced.
• An SiC substrate which is distinguished by its radiation permeability and electrical conductivity, is particularly suitable as the epitaxial substrate.
• the refractive index of SiC is larger than the refractive index of one
• GaN-based multilayer structure This advantageously means that no total reflection of the radiation generated in the active layer occurs when it enters the substrate.
• the region of the substrate 3 adjoining the lower electrode 29 is preferably cuboid or cuboid. Through this design with mutually orthogonal or parallel parallel boundary surfaces in this area, the assembly of the semiconductor chip is facilitated. This applies in particular to automatic assembly systems that are designed for the assembly of conventional cuboid or cube-shaped chips.
• FIGS. 6 and 7 show further exemplary embodiments of the invention which are likewise distinguished by a high degree of decoupling due to a special shape of the substrate 3.
• the substrate 3 initially forms an acute angle ⁇ with its long sides relative to the interface 31.
• the longitudinal sides 6 increasingly pivot in the direction of the lower electrode 29.
• the side surfaces 6 are concave and have a smooth transition to a preferably cuboid or cube-shaped stump 30.
• the formation of the stump 30 was finally dispensed with.
• the substrate 3 tapers over the entire thickness.
• the beveled long sides 6 in the manner of a Fresnel lens from partial surfaces arranged offset with respect to one another.
• the rectangular cross sections of the semiconductor chip 1 are maintained, at least in outline.
• the layout of the semiconductor chip 1 or 26 does not necessarily have to be rectangular.
• the layout of the semiconductor chip 1 or 26 can also have the shape of a tilted parallelogram, a trapezoid or a polygon.
• An InGaN semiconductor chip has an active area that is to be enlarged by a factor of 4.
• the results of the estimation are shown in Table 1.
• the proportions of the outcoupled radiation based on the total outcoupling from the standard chip are given in the last three columns.
• the semiconductor chip 26 from FIG. 5 has an improvement factor of 1.8, while the gain in the semiconductor chip 1 shown in FIGS. 1 a and 1 b is approximately 15%.
• the luminous efficacy can thus be increased significantly.
• the considerations presented here also apply to a semiconductor chip in which the active layer has transverse sides and long sides of the same length and in which the substrate has an elongated shape. This is particularly useful if the active layer itself has a sufficiently good thermal conductivity to dissipate the heat loss generated in the active zone, and if, on the other hand, the substrate has a poor thermal conductivity and therefore requires large cross-sectional areas to dissipate the heat loss can.

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Citations (15)

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• 2000
  • 2000-08-11 DE DE10039433.7A patent/DE10039433B4/de not_active Expired - Fee Related
• 2001
  • 2001-07-24 CN CNB2006101059281A patent/CN100541841C/zh not_active Expired - Lifetime
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  • 2001-07-24 WO PCT/DE2001/002801 patent/WO2002015287A1/de not_active Ceased
  • 2001-07-24 DE DE50115638T patent/DE50115638D1/de not_active Expired - Lifetime
  • 2001-07-24 US US10/343,851 patent/US6891199B2/en not_active Expired - Lifetime
  • 2001-07-24 JP JP2002520316A patent/JP2004507095A/ja active Pending
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