Light emitting diode chip structure with electrode extensions and graded via holes

Abstract

Solid state lighting devices including light emitting diode (LED) chips are disclosed, and more particularly LED chips structures having electrode extensions and graded via arrangements. Electrode extensions and vias are formed on opposite sides of an active LED structure as part of anode and cathode connections. Graded via arrangements include variable diameters and / or variable via spacing relative to electrode extensions and electrode pads. Additional structures include variable width electrode extensions relative to vias and / or electrode pads. Layouts of graded vias and corresponding electrode extensions are disclosed for improving uniformity of recombination efficiency across LED chip areas, and providing improvements in current injection, current droop, and overall emission efficiency.

Description

Technical Field

[0001] This disclosure relates to solid-state lighting devices including light-emitting diode (LED) chips, and more specifically to LED chip structures having electrode extensions and gradient vias. Background Technology

[0002] Solid-state lighting devices, such as light-emitting diodes (LEDs), are increasingly used in consumer and commercial applications. Advances in LED technology have resulted in efficient, mechanically robust, and long-lasting light sources. Consequently, modern LEDs have enabled a variety of new display applications and are increasingly used in general lighting applications, often replacing incandescent and fluorescent light sources.

[0003] LEDs are solid-state devices that convert electrical energy into light, and typically include one or more active layers (or active regions) of semiconductor material disposed between oppositely doped n-type and p-type layers. When a bias voltage is applied across the doped layers, holes and electrons are injected into one or more active layers, where they recombine and produce emission, such as visible or ultraviolet light. The active regions can be made of, for example, gallium nitride, gallium phosphide, aluminum nitride, and / or gallium arsenide-based materials and / or organic semiconductor materials. Photons generated by the active regions are emitted in various directions.

[0004] Typically, it is desirable to operate LEDs with the highest possible light emission efficiency, which can be measured by the relationship between emission intensity and output power (e.g., lumens per watt). A practical goal of improving emission efficiency is to maximize the extraction of light emitted by the active region in the desired light transmission direction. The light extraction and external quantum efficiency of an LED can be limited by the extent to which current can diffuse within the LED. To improve current diffusion in LEDs, especially larger-area LEDs, it has been found useful to add highly conductive layers to one or more epitaxial layers of the LED. The electrodes of an LED can have a large surface area and can include various electrode extensions or fingers configured to guide and distribute current across the LED.

[0005] With the advancement of modern LED technology, the field continues to seek improved LED and solid-state lighting devices with desired lighting characteristics that can overcome the challenges associated with traditional lighting devices. Summary of the Invention

[0006] This disclosure relates to solid-state lighting devices including light-emitting diode (LED) chips, and more specifically to LED chip structures having electrode extensions and a gradient via arrangement. The electrode extensions and vias are formed on opposite sides of an active LED structure as part of an anode and cathode connection. The gradient via arrangement includes variable diameters and / or variable via spacing relative to the electrode extensions and electrode pads. Additional structures include variable-width electrode extensions relative to the vias and / or electrode pads. The disclosed layout of the gradient vias and corresponding electrode extensions is intended to improve the uniformity of recombination efficiency across LED chip regions and provide improvements in current injection, current drop, and overall emission efficiency.

[0007] In one aspect, an LED chip includes: an active LED structure comprising a first layer of a first conductivity type, a second layer of a second conductivity type opposite to the first conductivity type, and an active layer located between the first layer and the second layer; a first electrode pad on a first side of the active LED structure, a first electrode extension and a second electrode extension on the first side of the active LED structure, the first electrode extension and the second electrode extension being electrically connected to the first electrode pad; and a plurality of vias on a second side of the active LED structure opposite to the first side, the plurality of vias being located between portions of the active LED structure perpendicularly aligned with the first electrode extension and the second electrode extension, and the diameter of each of the plurality of vias varying with distance from the first electrode pad. In some embodiments, the plurality of vias are arranged in a column across the second side of the active LED structure. In some embodiments, the diameter of each of the plurality of vias gradually decreases with increasing distance from the first electrode pad. In some embodiments, the diameter of each of the plurality of vias gradually increases with increasing distance from the first electrode pad. The LED chip may further include a second electrode pad on a first side of the active LED structure, wherein the first electrode pad is arranged near a first edge of the active LED structure, the second electrode pad is arranged near a second edge of the active LED structure, and the second edge is opposite to the first edge. In some embodiments, the diameter of each of the plurality of vias gradually decreases as the distance from the first electrode pad and the second electrode pad increases toward the center of the active LED structure. In some embodiments, the diameter of each of the plurality of vias gradually increases as the distance from the first electrode pad and the second electrode pad increases toward the center of the active LED structure.

[0008] The LED chip may further include: a second electrode pad, a third electrode pad, and a fourth electrode pad on a first side of the active LED structure; wherein the first and second electrode pads are arranged close to a first edge of the active LED structure, and the third and fourth electrode pads are arranged close to a second edge of the active LED structure, with the second edge opposite to the first edge. In some embodiments, the first electrode pad is an electrode strip arranged close to the first edge of the active LED structure.

[0009] In some embodiments: the active LED structure includes a first edge and a second edge opposite to each other, and a third edge and a fourth edge opposite to each other; a plurality of through holes are arranged in a first through hole column and a second through hole column, both extending between the first edge and the second edge of the active LED structure; and the position of the through holes in the first through hole column is offset relative to the position of the through holes in the second through hole column in a direction from the third edge to the fourth edge.

[0010] In some embodiments: a plurality of through holes are arranged in a first through hole column and a second through hole column; and the total number of through holes in the first through hole column is different from the total number of through holes in the second through hole column.

[0011] In another aspect, an LED chip includes: an active LED structure comprising a first layer of a first conductivity type, a second layer of a second conductivity type opposite to the first conductivity type, and an active layer located between the first and second layers; a first electrode pad on a first side of the active LED structure, a first electrode extension and a second electrode extension on the first side of the active LED structure, the first electrode extension and the second electrode extension being electrically connected to the first electrode pad; and a plurality of vias on a second side of the active LED structure opposite to the first side, the plurality of vias being located between portions of the active LED structure perpendicularly aligned with the first electrode extension and the second electrode extension, and the spacing between adjacent vias of the plurality of vias varying with distance from the first electrode pad. In some embodiments, the plurality of vias are arranged in a column across the second side of the active LED structure, and the spacing increases with increasing distance from the first electrode pad. In some embodiments, the diameter of each via of the plurality of vias increases along the column with increasing distance from the first electrode pad. The LED chip may further include: a second electrode pad on a first side of the active LED structure, wherein the first electrode pad is arranged near a first edge of the active LED structure, the second electrode pad is arranged near a second edge of the active LED structure, and the second edge is opposite to the first edge; wherein the spacing between adjacent vias in the plurality of vias is highest at the center near the first side of the active LED structure. In some embodiments: the plurality of vias are arranged in multiple columns near the first electrode pad between the first electrode extension and the second electrode extension; and the plurality of vias are arranged in a single column between the first electrode extension and the second electrode extension at a position farther from the first electrode pad than the plurality of columns. In some embodiments, the diameter of each via in the plurality of vias increases with increasing distance from the first electrode pad. In some embodiments, the first electrode pad is an electrode strip arranged near the first edge of the active LED structure. In some embodiments: the active LED structure includes a first edge and a second edge opposite to each other, and a third edge and a fourth edge opposite to each other; a plurality of through holes are arranged in a first through hole column and a second through hole column, both extending between the first edge and the second edge of the active LED structure; and the position of the through holes in the first through hole column is offset relative to the position of the through holes in the second through hole column in a direction from the third edge to the fourth edge. In some embodiments: the plurality of through holes are arranged in a first through hole column and a second through hole column; and the total number of through holes in the first through hole column is different from the total number of through holes in the second through hole column.

[0012] In another aspect, an LED chip includes: an active LED structure comprising a first layer of a first conductivity type, a second layer of a second conductivity type opposite to the first conductivity type, and an active layer located between the first and second layers; an electrode pad on a first side of the active LED structure; a plurality of vias on a second side of the active LED structure opposite to the first side, wherein the diameter of each via varies with distance from the electrode pad; and a first electrode extension on the first side of the active LED structure, the first electrode extension being electrically connected to the electrode pad, wherein the width of the first electrode extension varies with distance from the electrode pad. In some embodiments, the width of the first electrode extension gradually decreases with increasing distance from the electrode pad. The LED chip may further include a second electrode extension on the first side of the active LED structure, the second electrode extension being electrically connected to the electrode pad, wherein the width of the second electrode extension gradually decreases with increasing distance from the electrode pad. In some embodiments, the plurality of vias are arranged in a column across the second side of the active LED structure, between portions of the active LED structure perpendicularly aligned with the first and second electrode extensions. In some embodiments, the spacing between adjacent vias in the plurality of vias increases with increasing distance from the electrode pads. In some embodiments, the diameter of each via in the plurality of vias increases along the column with increasing distance from the electrode pads. In some embodiments, the electrode pads are electrode strips arranged close to a first edge of the active LED structure. In some embodiments: the active LED structure includes a first edge and a second edge opposite to each other, and a third edge and a fourth edge opposite to each other; the plurality of vias are arranged in a first via column and a second via column, both extending between the first and second edges of the active LED structure; and the position of the vias in the first via column is offset relative to the position of the vias in the second via column in a direction from the third edge to the fourth edge. In some embodiments: the plurality of vias are arranged in a first via column and a second via column; and the total number of vias in the first via column is different from the total number of vias in the second via column.

[0013] On the other hand, any of the foregoing aspects may be combined, individually or jointly, and / or the various individual aspects and features of this document may be combined to obtain additional advantages. Unless otherwise indicated herein, any of the various features and elements disclosed herein may be combined with one or more other disclosed features and elements.

[0014] Those skilled in the art will appreciate the scope of this disclosure and realize its additional aspects after reading the following detailed description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate several aspects of this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0016] Figure 1 This is a cross-sectional view of a portion of a light-emitting diode (LED) chip according to the principles of this disclosure, showing electrode extensions and vias arranged on opposite sides of an active LED structure.

[0017] Figure 2 Is with Figure 1 A top view of a similar LED chip, which has an electrode extension and a layout with through holes of variable diameter according to the principles of this disclosure.

[0018] Figure 3 This is a top view of an LED chip, which is related to... Figure 2 Similar to LED chips, the difference lies in that the diameter of the via increases with the distance from the electrode pad.

[0019] Figure 4 This is a top view of an LED chip, which is related to... Figure 2 The difference between the two types of LED chips is that the diameter of the through holes first decreases and then increases along each column of through holes.

[0020] Figure 5 This is a top view of an LED chip, which is related to... Figure 4 The difference between the two types of LED chips is that the diameter of the through holes first increases and then decreases along each row of through holes.

[0021] Figure 6 This is a top view of an LED chip, which is related to... Figure 5 Similar to LED chips, and also includes multiple electrode pads near each opposite edge of the LED chip.

[0022] Figure 7 This is a top view of an LED chip, which is related to... Figure 3 Similar to LED chips, this implementation involves varying the via spacing with distance from the electrode pads.

[0023] Figure 8 This is a top view of an LED chip, which is related to... Figure 7 The difference between the two types of LED chips is that the electrode pads are positioned close to the relative edges of the LED chip.

[0024] Figure 9 This is a top view of an LED chip, which is related to... Figure 7 Similar to LED chips, this implementation involves through-holes formed in multiple columns between portions of adjacent electrode extensions.

[0025] Figure 10 This is a top view of an LED chip, which is related to... Figure 7 Similar to LED chips, this implementation allows the width of one or more electrode extensions to vary with the distance from one or more electrode pads.

[0026] Figure 11 This is a top view of an LED chip, which is related to... Figure 3 Similar to LED chips, the implementation for electrode pads is an electrode strip located near the edge of the LED chip.

[0027] Figure 12 This is a top view of an LED chip, which is related to... Figure 11 Similar to LED chips, this implementation method involves offsetting the position of the via in each column from the position of the via in the adjacent column. Detailed Implementation

[0028] The embodiments described below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode for practicing the embodiments. Upon reading the following description in conjunction with the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and recognize the application of these concepts not specifically mentioned herein. It should be understood that these concepts and applications fall within the scope of this disclosure and the appended claims.

[0029] It should be understood that although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0030] It should be understood that when a component, such as a layer, region, or substrate, is referred to as being "on" or extending "on" another component, it can be directly on or directly extending onto the other component, or intermediate components may be present. Conversely, when a component is referred to as being "directly on" or directly extending "on" another component, no intermediate components are present. Similarly, it should be understood that when a component, such as a layer, region, or substrate, is referred to as being "above" or extending "above" another component, it can be directly above or directly extending above the other component, or intermediate components may be present. Conversely, when a component is referred to as being "directly above" or directly extending "above" another component, no intermediate components are present. It should also be understood that when a component is referred to as being "connected" or "attached" to another component, it can be directly connected or attached to the other component, or intermediate components may be present. Conversely, when a component is referred to as being "directly connected" or "directly attached" to another component, no intermediate components are present.

[0031] Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe the relationship of one element, layer, or region to another element, layer, or region as shown in the accompanying drawings. It should be understood that these terms, and the terms discussed above, are intended to cover different orientations of the device other than those depicted in the accompanying drawings.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” “having,” and / or “containing” as used herein specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0033] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It should also be understood that the terms used herein shall be interpreted as having the same meaning as in the context of this specification and related art, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0034] Embodiments are described herein with reference to illustrative drawings of embodiments of this disclosure. Therefore, the actual dimensions of layers and elements may differ, and deviations from the illustrated shapes are expected, for example, due to manufacturing techniques and / or tolerances. For instance, areas shown or described as squares or rectangles may have circular or curved features, and areas shown as straight lines may have some irregularity. Therefore, the areas shown in the figures are schematic, and their shapes are not intended to show the precise shapes of areas of the device, nor are they intended to limit the scope of this disclosure. Furthermore, for illustrative purposes, the dimensions of structures or areas may be exaggerated relative to additional structures or areas, and are thus provided to illustrate the overall structure of the subject matter, and may be drawn to scale or not. Common elements in the figures may be indicated herein by common element numbers and will not be redescribed subsequently.

[0035] This disclosure relates to solid-state lighting devices including light-emitting diode (LED) chips, and more specifically to LED chip structures having electrode extensions and a gradient via arrangement. The electrode extensions and vias are formed on opposite sides of an active LED structure as part of an anode and cathode connection. The gradient via arrangement includes variable diameters and / or variable via spacing relative to the electrode extensions and electrode pads. Additional structures include variable-width electrode extensions relative to the vias and / or electrode pads. The disclosed layout of the gradient vias and corresponding electrode extensions is intended to improve the uniformity of recombination efficiency across LED chip regions and to provide improvements in current injection, current drop, and overall emission efficiency.

[0036] LED chips typically include an active LED structure or region, which may have many different semiconductor layers arranged in different ways. The fabrication and operation of LEDs and their active structures are generally known in the art and will only be briefly discussed herein. The layers of the active LED structure can be fabricated using known processes, with metal-organic chemical vapor deposition being a suitable process. The layers of an active LED structure may include many different layers and typically include an active layer sandwiched between n-type and p-type oppositely doped epitaxial layers, all of which are sequentially formed on a growth substrate. It should be understood that the active LED structure may also include additional layers and elements, including but not limited to buffer layers, nucleation layers, superlattice structures, undoped layers, cladding layers, contact layers, current diffusion layers, and light extraction layers and elements. The active layer may include a single quantum well, multiple quantum wells, a double heterostructure, or a superlattice structure.

[0037] Active LED structures can be fabricated from various material systems, some of which are based on Group III nitrides. Group III nitrides are semiconductor compounds formed between nitrogen (N) and elements from Group III of the periodic table (typically aluminum (Al), gallium (Ga), and indium (In)). Gallium nitride (GaN) is a common binary compound. Group III nitrides also include ternary and quaternary compounds, such as aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), and aluminum indium gallium nitride (AlInGaN). For Group III nitrides, silicon (Si) is a common n-type dopant, and magnesium (Mg) is a common p-type dopant. Therefore, the active layer, n-type layer, and p-type layer can comprise one or more layers of GaN, AlGaN, InGaN, and AlInGaN. For Group III nitride-based material systems, these layers are either undoped or doped with Si or Mg. Other material systems include organic semiconductors and other Group III-V systems, such as gallium phosphide (GaP), gallium arsenide (GaAs), and related compounds. Active LED structures can be grown on a growth substrate, which can include many materials such as sapphire, silicon carbide (SiC), aluminum nitride (AlN), and GaN.

[0038] Different implementations of active LED structures can emit light of different wavelengths depending on the composition of the active layer and the n-type and p-type layers. In some implementations, the active LED structure can emit blue light with a peak wavelength range of approximately 430 nanometers (nm) to 480 nm. In other implementations, the active LED structure can emit green light with a peak wavelength range of 500 nm to 570 nm. In other implementations, the active LED structure can emit generally red or yellow light with a peak wavelength range of 600 nm to 700 nm. Some implementations disclosed herein are well-suited to various sub-ranges within the 600 nm to 700 nm range, such as the 650 nm to 670 nm peak wavelength range and / or the 610 nm to 630 nm peak wavelength range depending on the application. In some implementations, aspects of this disclosure are applicable to active LED structures that emit light with peak wavelengths in any region of the visible spectrum, for example, with peak wavelengths primarily in the 400 nm to 700 nm range.

[0039] In another embodiment, the active LED structure can be configured to emit light beyond the visible spectrum, including one or more portions of the ultraviolet (UV), infrared (IR), or near-IR spectrum. The UV spectrum is typically divided into three wavelength range categories, denoted by the letters A, B, and C. In this way, UV-A light is typically defined as a peak wavelength range of 315 nm to 400 nm, UV-B is typically defined as a peak wavelength range of 280 nm to 315 nm, and UV-C is typically defined as a peak wavelength range of 100 nm to 280 nm. UV LEDs are of particular interest in applications related to the disinfection of microorganisms in air, water, and surfaces. In other applications, UV LEDs may also incorporate one or more luminescent materials to provide a focused emission LED package with broad spectrum and improved color quality for visible light applications. The near-IR and / or IR wavelengths of the LED structures disclosed herein may have wavelengths higher than 700 nm, for example, in the range of 750 nm to 1100 nm or greater.

[0040] Light emitted from the active layer or region of an LED chip is typically emitted in multiple directions. For directional applications, internal mirrors or external reflective surfaces can be used to redirect as much light as possible to the desired emission direction. Internal mirrors can comprise a single layer or multiple layers. Some multilayer mirrors include a metallic reflective layer and a dielectric reflective layer, wherein the dielectric reflective layer is disposed between the metallic reflective layer and multiple semiconductor layers. A passivation layer is disposed between the metallic reflective layer and a first electrical contact and a second electrical contact, wherein the first electrical contact is arranged to be electrically connected to a first semiconductor layer, and the second electrical contact is arranged to be electrically connected to a second semiconductor layer. For single-layer or multilayer mirrors including surfaces with a reflectivity of less than 100%, some light may be absorbed by the mirror. Additionally, light redirected through the active LED structure may be absorbed by other layers or elements within the LED chip.

[0041] As used herein, a layer or region of a light-emitting device may be considered "transparent" when at least 80% of the emitted radiation incident on the layer or region passes through it. Furthermore, as used herein, a layer or region of an LED may be considered "reflective" or embody a "mirror" or "reflector" when at least 80% of the emitted radiation incident on the layer or region is reflected. In some embodiments, the emitted radiation includes visible light, such as blue and / or green LEDs with or without light-emitting material. In other embodiments, the emitted radiation may include invisible light. In some embodiments, a "transparent" material may be configured to transmit at least 50% of the emitted radiation of the desired wavelength.

[0042] This disclosure is applicable to LED chips having various geometries, including vertical geometries. Vertical geometry LED chips typically include anode and cathode connections on opposite sides or faces of the LED chip. In some embodiments, vertical geometry LED chips may further include a growth substrate disposed between the anode and cathode connections. In other embodiments, the LED chip structure may include a carrier submount, wherein the growth substrate is removed. In further embodiments, any principles described herein apply to flip-chip structures, wherein the anode and cathode connections are formed from the same side of the LED chip for flip-chip mounting to another surface.

[0043] This disclosure applies to LED chips with a current diffusion structure that distributes current across an active LED structure region. The current diffusion structure may include various conductive layers, contacts, electrode extensions or fingers, and / or vias that effectively guide current through the LED chip to reduce current congestion. In vertical LED chip structures, n-type and p-type contacts are typically formed from opposite sides of the active LED structure. For larger area LED chips, contacts and corresponding electrode extensions may be arranged along the top of the active LED structure to contact one side of the active LED structure, while bottom contacts and corresponding vias may be arranged to contact opposite sides of the active LED structure. As used herein, an electrode extension may refer to an elongated conductive material that is continuous with and extends from an electrode pad or contact pad of the LED chip. The electrode pad may receive external electrical connections, such as wire bonding, and the electrode extension extends away from the electrode pad for current diffusion. As used herein, the terms electrode extension, contact extension, electrode finger, and contact finger are used interchangeably.

[0044] As described above, the principles of this disclosure are applicable to active LED structures that emit peak wavelengths spanning a wide range of visible and invisible wavelengths. In some embodiments, aspects of this disclosure are particularly useful for active LED structures configured to emit generally red or yellow light in the peak wavelength range of 600 nm to 700 nm. Some embodiments disclosed herein are well-suited to various sub-ranges within the 600 nm to 700 nm range, such as peak wavelength ranges of 650 nm to 670 nm and / or 610 nm to 630 nm, depending on the application. Such active LED structures may comprise GaP- and / or GaAs-based materials, such as AlInGaP materials for any of the n-type, p-type, and active layers.

[0045] Figure 1This is a cross-sectional view of a portion of an LED chip 10 according to the principles of this disclosure, showing electrode extensions 12 and through-holes 14 arranged on opposite sides of an active LED structure 16. Figure 1 In the diagram, the active LED structure 16 is generally shown as having a p-type layer 18, an n-type layer 22, and an active layer 20 located therebetween. It should be understood that the active LED structure 16 may include additional layers, and each of the p-type layer 18, the n-type layer 22, and the active layer 20 may include multiple sublayers. The active LED structure 16 may be formed on a substrate 24. In some embodiments, the substrate 24 embodies a carrier substrate supporting the active LED structure 16. In such embodiments, the active LED structure 16 may first be grown on a growth substrate, then the substrate 24 (e.g., a carrier substrate) is bonded to the side of the active LED structure opposite the growth substrate, and then the growth substrate is removed. In some embodiments, the p-type layer 18 is located between the active layer 20 and the carrier substrate 24, such as... Figure 1 As shown. In other embodiments, it should be understood that the doping or conductivity order can be reversed, such that the n-type layer 22 is located between the active layer 20 and the carrier substrate 24. The following... Figure 1 The discussion takes place in the context that the p-type layer 18 is closer to the carrier substrate 24 than the n-type layer 22. However, it should be understood that these principles also apply to embodiments with the conductivity type reversed. The substrate 24 can comprise many different materials, among which silicon or other conductive materials are well-suited for vertical chip structures.

[0046] exist Figure 1 In this configuration, electrode extension 12 is located on a first side 16' (or top side) of the active LED structure 16 opposite to the carrier substrate 24. As will be shown in the accompanying drawings below, electrode extension 12 can extend from a top electrode pad also on the first side 16'. Electrode extension 12 provides a portion of an n-type contact to the n-type layer 22. The LED chip 10 may include one or more electrically insulating layers 26 between the active LED structure 16 and the carrier substrate 24. In one example, the insulating layer 26 may form part of a mirror or reflective layer positioned to redirect downward-propagating light through the active LED structure 16 and out from the top side of the LED chip 10. In this regard, vias 14 are arranged on a second side 16'' (or bottom side) of the active LED structure 16 opposite to the first side 16' to provide a conductive path through the insulating layer 26 between the carrier substrate 24 and the active LED structure 16. Bottom electrode pads 27 may be formed on the bottom of the carrier substrate 24. As an example, via 14 provides a portion of the p-type contact between the bottom electrode pad 27 and the p-type layer 18.

[0047] like Figure 1As shown, distance D can be defined as the lateral distance or spacing between electrode extension 12 and via 14, as measured in a horizontal plane between the nearest peripheral edges of electrode extension 12 and via 14. Since electrode extension 12 and via 14 are on opposite sides of active LED structure 16, distance D is measured between a first plane P1 perpendicularly aligned to the edge of electrode extension 12 and a second plane P2 perpendicularly aligned to the edge of via 14 closest to electrode extension 12. When electrically activated, active LED structure 16 generates light through the recombination of electrons and holes near active layer 20. Improved recombination efficiency is achieved in the portion of active LED structure 16 located between electrode extension 12 and via 14. As shown, via 14 can be laterally spaced from electrode extension 12 by distance D to reduce the amount of light lost due to absorption by electrode extension 12. For example, electrode extension 12 may include a conductive metal, such as gold (Au) or an alloy thereof, which can reflect and / or absorb light generated in active LED structure 16. By positioning the via 14 at a lateral offset distance D from the electrode extension 12 directly below it, an increased amount of light can escape without interacting with the electrode extension 12. However, the electrostatic potential decreases with increasing distance D, so if the distance D is too large, the spacing between the via 14 and the electrode extension 12 may include a region where the field strength is significantly reduced, thereby decreasing the recombination efficiency.

[0048] Figure 2 This is a top view of an LED chip 28, similar to the LED chip 10, arranged with electrode extensions 12 and through-holes 14 of variable diameter, according to the principles of this disclosure. Since this view is taken from the top of the LED chip 28, the electrode extensions 12 are visible at the top surface of the LED chip 28. The through-holes 14, although located below the top surface of the LED chip 28, are... Figure 2 As shown, it is still visible. The electrode extension 12 is interconnected in a continuous manner with one or more top electrode pads 30 on the top surface. In this way, the electrode pads 30 can receive external electrical connections, such as wire bonding, and the electrode extension 12 diffuses current along the region of the LED chip 28. Figure 2In this configuration, electrode pads 30 are arranged close to the same edge of the LED chip 28, and electrode extensions 12 extend linearly toward opposite edges of the LED chip 28. In some embodiments, from a top view, electrode extensions 12 and vias 14 are aligned in alternating linear columns. This arrangement provides a variable distance between each point on each electrode extension 12 and the nearest via 14. Therefore, certain regions between electrode extensions 12 and the nearest via 14 may lie in areas of reduced field strength, exhibiting decreased recombination efficiency. As shown, the diameter of the via 14 varies with distance from the electrode pads 30 to improve recombination efficiency. For example, the diameter of the via 14 may gradually decrease from large to small within each column, and decrease with increasing distance from one or more electrode pads 30. In this way, vias 14 with larger diameters are positioned closer to the electrode pads 30, where current injection and / or potential may be highest.

[0049] Figure 3 Is with Figure 2 A top view of LED chip 32, similar to LED chip 28, differs in that the diameter of the via 14 increases with distance from electrode pad 30. As shown, vias 14 with smaller diameters are positioned closer to electrode pad 30, and vias 14 with the largest diameters are positioned at or near the distal end of electrode extension 12, near the opposite edge of LED chip 32. In this embodiment, vias 14 with larger diameters are positioned furthest from electrode pad 30, where current injection is likely to be lowest. The vias 14 are selected to gradually decrease in distance from electrode pad 30 (e.g., ...). Figure 2 ) or it gradually increases with the distance of 30 from the electrode pad (e.g., Figure 3 The current diffusion capacity (CDC) can be determined by a variety of factors. Such factors may include differences in the electrostatic field related to various LED chip structures, material systems, and / or the current diffusion capacity of the electrode extensions 12. Other factors and / or benefits include helping to drive a more uniform distribution of charge carriers (i.e., holes and electrons), which leads to improved recombination efficiency for light generation and reduced local heating from localized charge carrier concentrations.

[0050] Figure 4 Is with Figure 2A top view of LED chip 34 similar to LED chip 28, except that the diameter of the vias 14 decreases and then increases along each column of vias 14. In some embodiments, the electrode pads 30 may be arranged close to opposite sides of the LED chip 34. Therefore, the diameter of the vias 14 in each column may decrease as the distance from each opposite electrode pad 30 increases toward the center of the LED chip 34. In this way, vias 14 with smaller diameters are arranged along the central portion of the LED chip 34 located between opposite electrode pads 30. In some embodiments, one or more, or even all, of the electrode extensions 12 may form a continuous structure with the two electrode pads 30.

[0051] Figure 5 Is with Figure 4 The LED chip 34 is a top view similar to the LED chip 36, except that the diameter of the vias 14 increases and then decreases along each column of vias 14. In some embodiments, the electrode pads 30 can be arranged close to opposite sides of the LED chip 36. Therefore, the diameter of the vias 14 in each column can increase as the distance from each opposite electrode pad 30 increases toward the center of the LED chip 36. In this way, the vias 14 with larger diameters are arranged along the central portion of the LED chip 36 located between the opposite electrode pads 30.

[0052] Figure 6 Is with Figure 5 A top view of LED chip 38, similar to LED chip 36, and also including a plurality of electrode pads 30 near each opposite edge of LED chip 38. As shown, the diameter of the through-hole 14 in each column is similar to that of LED chip 38. Figure 5 A similar approach increases as the distance from each opposing electrode pad 30 increases toward the center of the LED chip 38. By having multiple electrode pads 30 near each opposing edge, further improvements in current injection, current drop, and efficiency can be achieved. As in the previous embodiments, one or more, or even all, of the electrode extensions 12 can form a continuous structure with all the electrode pads 30.

[0053] Figure 7 Is with Figure 3A top view of an LED chip 40 similar to the LED chip 32 is shown, illustrating an implementation where the spacing of the vias 14 varies with distance from the electrode pads 30. As used herein, spacing can refer to the distance between adjacent or next-adjacent vias 14, such as when measured between the center points of adjacent vias 14. As shown, the spacing between adjacent vias 14 is smaller near the edge where the electrode pads 30 of the LED chip 40 are located. In this way, an increased number of vias 14 can be located near the electrode pads 30 where current injection is likely to be highest. In each row of vias 14, the spacing can increase with increasing distance from the electrode pads 30. In some embodiments, the diameter of the vias 14 can also increase with increasing distance from the electrode pads 30 in each row of vias 14. For example, in Figure 7 In this process, a through-hole 14 with a larger diameter is positioned close to the edge of the LED chip 40 opposite to the electrode pad 30.

[0054] Figure 8 Is with Figure 7 The LED chip 40 is a top view similar to the LED chip 42, except that the electrode pads 30 are positioned close to the opposite edges of the LED chip 42. In this arrangement, the spacing between adjacent vias 14 in each column can increase towards the center of the LED chip 42 as the distance from each electrode pad 30 increases. Therefore, the maximum spacing between adjacent vias 14 is formed at or near the center of each column of vias 14. As shown, the diameter of the vias 14 can first increase and then decrease along each column of vias 14. In this way, the diameter of the vias 14 in each column can increase towards the center of the LED chip 42 as the distance from each opposite electrode pad 30 increases, such that vias 14 with larger diameters are arranged along the central portion of the LED chip 42.

[0055] Figure 9 Is with Figure 7 A top view of an LED chip 44 similar to LED chip 40, for an embodiment where through-holes 14 are formed in multiple columns between portions of adjacent electrode extensions 12. As for... Figure 7 As described, the spacing and diameter of the vias 14 closest to the electrode pad 30 can be smaller than the spacing and diameter of the vias 14 farther from the electrode pad 30. In this respect, the smaller spacing and diameter of the vias 14 closer to the electrode pad 30 allows for the formation of multiple rows of vias 14 at these locations. As the distance from the electrode pad 30 increases, the spacing and diameter of the vias 14 can increase, such that the vias 14 are arranged in a single row between adjacent electrode extensions 12.

[0056] Figure 10 Is with Figure 7A top view of an LED chip 46 similar to the LED chip 40 is provided for an embodiment where the width of one or more electrode extensions 12 varies with distance from one or more electrode pads 30. For example, the width of one or more electrode extensions 12 is wider near the electrode pads 30 and narrower near the edges of the LED chip 46 opposite to the electrode pads 30. In this way, the electrode extensions 12 are formed to cover a larger surface area of ​​the LED chip 46 near the electrode pads 30 (where current injection may be highest). As shown, the vias 14 in each column can have a diameter and / or spacing that increases with distance from the electrode pads 30. Thus, the largest diameter via with the largest spacing can be positioned with the narrowest width furthest from the electrode pads 30 and closest to the electrode extension 12. The inverse relationship between the decreasing width of the electrode extensions 12 and the increasing spacing and / or diameter of the vias 14 can increase the uniformity of the lateral spacing between each via 14 and one or more nearest electrode extensions 12. In this context, the lateral spacing can be measured in a direction perpendicular to each column of vias 14. Therefore, the location of each via 14 can be set in a region with a higher potential to improve emission efficiency, while also providing an improved current distribution across the LED chip 46.

[0057] Figure 11 Is with Figure 3 The figure shows a top view of an LED chip 48 similar to the LED chip 32, with the electrode pads 30 being an embodiment of an electrode strip near the edge of the LED chip 32. As shown, each electrode extension 12 is connected to the electrode pad 30 near the edge of the LED chip 48. In some embodiments, the electrode pad 30 is a single electrode pad extending continuously between each electrode extension 12. In other embodiments, the length of the electrode pad 30 along the edge of the LED chip 48 is greater than the distance measured between the outermost columns of the vias 14. Figure 11 The single electrode pad 30 in rod form shown is advantageous for higher current applications. In this respect, multiple wire bonds can be electrically connected to the single electrode pad 30. The diameter and / or spacing of the vias 14 in each column can also be varied as previously described. Figure 11 The electrode pad 30 shown can be implemented in any of the previous embodiments, including Figures 2 to 10 .

[0058] Figure 12 Is with Figure 11A top view of an LED chip 50 similar to LED chip 48, showing an implementation where the position of the via 14 in each column is offset from the position of the via 14 in adjacent columns. Columns of via 14 extend between opposite edges of the LED chip 50. As shown, the offset position of the via 14 in each column avoids forming linear rows of via 14 in the direction between other opposite edges of the LED chip 50 or perpendicular to the column. This arrangement improves the uniformity of the via 14 relative to the electrode extension 12, thereby improving the uniformity of carrier distribution. In some embodiments, the offset nature of the via 14 provides a different total number of vias in adjacent columns. The diameter and / or spacing of the via 14 in each column can also be varied as previously described. Figure 12 The arrangement of the through holes 14 shown can be implemented in any of the previous embodiments, including Figures 2 to 11 .

[0059] As described above, the principles of this disclosure provide various layouts of vias, electrode extensions, and / or electrode pads tailored to local electrostatic field differences in various LED chip structures. Such layouts can provide carrier (i.e., holes and electrons) distribution with improved uniformity, thereby increasing recombination efficiency for light generation while reducing localized heating originating from localized carrier concentration.

[0060] It is anticipated that any of the foregoing aspects and / or the various individual aspects and features described herein can be combined to obtain additional advantages. Any of the various embodiments disclosed herein can be combined with one or more other disclosed embodiments, unless otherwise indicated herein.

[0061] Those skilled in the art will recognize improvements and modifications to the preferred embodiments of this disclosure. All such improvements and modifications are considered to fall within the scope of the concepts disclosed herein and the appended claims.

Claims

1. A light-emitting diode (LED) chip, comprising: An active LED structure includes a first layer of a first conductivity type, a second layer of a second conductivity type opposite to the first conductivity type, and an active layer located between the first layer and the second layer; On the first electrode pad of the first side of the active LED structure, In the first electrode extension and the second electrode extension on the first side of the active LED structure, the first electrode extension and the second electrode extension are electrically connected to the first electrode pad. as well as A plurality of through holes are located on the second side of the active LED structure opposite to the first side. The plurality of through holes are located between portions of the active LED structure that are vertically aligned with the first electrode extension and the second electrode extension, and the diameter of each of the plurality of through holes varies with the distance from the first electrode pad.

2. The LED chip according to claim 1, wherein, The plurality of through holes are arranged in a column across the second side of the active LED structure.

3. The LED chip according to claim 1, wherein, The diameter of each of the plurality of through holes gradually decreases as the distance from the first electrode pad increases.

4. The LED chip according to claim 1, wherein, The diameter of each of the plurality of through holes gradually increases with the distance from the first electrode pad.

5. The LED chip according to claim 1, further comprising a second electrode pad on the first side of the active LED structure, wherein, The first electrode pad is arranged close to a first edge of the active LED structure, and the second electrode pad is arranged close to a second edge of the active LED structure, with the second edge opposite to the first edge.

6. The LED chip according to claim 5, wherein, The diameter of each of the plurality of vias gradually decreases as the distance from the first electrode pad and the second electrode pad increases toward the center of the active LED structure.

7. The LED chip according to claim 5, wherein, The diameter of each of the plurality of vias gradually increases as the distance from the first electrode pad and the second electrode pad increases toward the center of the active LED structure.

8. The LED chip according to claim 1, further comprising: The second electrode pad, the third electrode pad, and the fourth electrode pad on the first side of the active LED structure; The first electrode pad and the second electrode pad are arranged close to the first edge of the active LED structure, and the third electrode pad and the fourth electrode pad are arranged close to the second edge of the active LED structure, with the second edge opposite to the first edge.

9. The LED chip according to claim 1, wherein, The first electrode pad is an electrode strip arranged close to the first edge of the active LED structure.

10. The LED chip according to claim 1, wherein: The active LED structure includes a first edge and a second edge opposite to each other, and a third edge and a fourth edge opposite to each other; The plurality of through holes are arranged into a first through hole column and a second through hole column, both extending between the first edge and the second edge of the active LED structure; and The position of the through hole in the first through hole column is offset relative to the position of the through hole in the second through hole column in the direction from the third edge to the fourth edge.

11. The LED chip according to claim 1, wherein: The plurality of through holes are arranged in a first through hole row and a second through hole row; and The total number of through holes in the first through hole column is different from the total number of through holes in the second through hole column.

12. A light-emitting diode (LED) chip, comprising: An active LED structure includes a first layer of a first conductivity type, a second layer of a second conductivity type opposite to the first conductivity type, and an active layer located between the first layer and the second layer; On the first electrode pad of the first side of the active LED structure, In the first electrode extension and the second electrode extension on the first side of the active LED structure, the first electrode extension and the second electrode extension are electrically connected to the first electrode pad. as well as In the active LED structure, a plurality of through holes are located on the second side opposite to the first side. The plurality of through holes are located between portions of the active LED structure that are vertically aligned with the first electrode extension and the second electrode extension, and the spacing between adjacent through holes varies with the distance from the first electrode pad.

13. The LED chip according to claim 12, wherein, The plurality of vias are arranged in columns across the second side of the active LED structure, and the spacing increases with the distance from the first electrode pad.

14. The LED chip according to claim 13, wherein, The diameter of each of the plurality of vias increases along the column as the distance from the first electrode pad increases.

15. The LED chip according to claim 12, further comprising: The second electrode pad on the first side of the active LED structure is arranged close to the first edge of the active LED structure, the second electrode pad is arranged close to the second edge of the active LED structure, and the second edge is opposite to the first edge. The spacing between adjacent through holes in the plurality of through holes is greatest at the center of the first side near the active LED structure.

16. The LED chip according to claim 12, wherein: The plurality of through-holes are arranged in multiple columns between the first electrode extension and the second electrode extension, near the first electrode pad; and The plurality of vias are arranged in a single row between the first electrode extension and the second electrode extension at a position farther from the first electrode pad than the plurality of columns.

17. The LED chip according to claim 16, wherein, The diameter of each of the plurality of through holes increases with the distance from the first electrode pad.

18. The LED chip according to claim 12, wherein, The first electrode pad is an electrode strip arranged close to the first edge of the active LED structure.

19. The LED chip according to claim 12, wherein: The active LED structure includes a first edge and a second edge opposite to each other, and a third edge and a fourth edge opposite to each other; The plurality of through holes are arranged into a first through hole column and a second through hole column, both extending between the first edge and the second edge of the active LED structure; and The position of the through hole in the first through hole column is offset relative to the position of the through hole in the second through hole column in the direction from the third edge to the fourth edge.

20. The LED chip according to claim 12, wherein: The plurality of through holes are arranged in a first through hole row and a second through hole row; and The total number of through holes in the first through hole column is different from the total number of through holes in the second through hole column.

21. A light-emitting diode (LED) chip, comprising: An active LED structure includes a first layer of a first conductivity type, a second layer of a second conductivity type opposite to the first conductivity type, and an active layer located between the first layer and the second layer; On the electrode pads of the first side of the active LED structure, A plurality of through-holes on the second side of the active LED structure opposite to the first side, wherein the diameter of each of the plurality of through-holes varies with the distance from the electrode pad; and In the first electrode extension on the first side of the active LED structure, the first electrode extension is electrically connected to the electrode pad, wherein the width of the first electrode extension varies with the distance from the electrode pad.

22. The LED chip according to claim 21, wherein, The width of the first electrode extension gradually decreases as the distance from the electrode pad increases.

23. The LED chip of claim 22, further comprising a second electrode extension on the first side of the active LED structure, the second electrode extension being electrically connected to the electrode pad, wherein, The width of the second electrode extension gradually decreases as the distance from the electrode pad increases.

24. The LED chip according to claim 23, wherein, The plurality of vias are arranged in a column across the second side of the active LED structure, and the plurality of vias are located between portions of the active LED structure that are vertically aligned with the first electrode extension and the second electrode extension.

25. The LED chip according to claim 24, wherein, The spacing between adjacent vias in the plurality of vias increases with the distance from the electrode pads.

26. The LED chip according to claim 24, wherein, The diameter of each of the plurality of vias increases along the column as the distance from the electrode pad increases.

27. The LED chip according to claim 21, wherein, The electrode pads are electrode strips arranged close to the first edge of the active LED structure.

28. The LED chip according to claim 21, wherein: The active LED structure includes a first edge and a second edge opposite to each other, and a third edge and a fourth edge opposite to each other; The plurality of through holes are arranged into a first through hole column and a second through hole column, both extending between the first edge and the second edge of the active LED structure; and The position of the through hole in the first through hole column is offset relative to the position of the through hole in the second through hole column in the direction from the third edge to the fourth edge.

29. The LED chip according to claim 21, wherein: The plurality of through holes are arranged in a first through hole row and a second through hole row; and The total number of through holes in the first through hole column is different from the total number of through holes in the second through hole column.

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